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Deleterious Effects Of Low Velocity Flow In Piping And Pipelines

Jan 29 2019 11:20 PM

Dear All,

Most of us know that high velocities in pipelines can lead to a plethora of operational and maintenance problems such as noise, vibrations, erosion of pipe material, and a combined erosion-corrosion problem. API RP 14E (now a defunct document), defines a formula for calculating erosional velocities in 2-phase flows mentioning that actual flowing velocities should be well below the calculated erosional velocities. ISO 13703 says the same about erosional velocities since it is based on API RP 14E, with the difference that the erosional velocity formula of API RP 14E is available in SI units. My blog entry “Erosion due to Flow” wherein the subject of erosional velocity is discussed in detail, has been widely read and commented. The link for this old entry of mine is given below:

https://www.cheresou...on-due-to-flow/

Today’s topic however deals with low velocities. The adjective I have used is deleterious for low velocities. The reason being that, while high velocities can have an immediate impact in terms of noise or vibrations in piping systems, the undesirable effect of low velocities in piping is more subtle and long-term. The adjective deleterious signifies this subtle and long-term effect of low velocities.

Let us come to those deleterious effects of low velocities in piping and pipelines. I will categorize the flow in pipes and pipelines based on the type of fluid and the fluid phase.

Flow of Slurries (liquid-solid homogeneous phase):
At very low flowing velocities, phase separation will occur of the solid particles, with the higher density solid particles tending to settle down at the pipe bottom of a horizontal pipe run. The settling will be even more at bends (direction change), or where there is a reduction in the pipe diameter. The deleterious effect is that over a period of time a layer of solid builds in the pipe and pipe fittings, reducing the pipe diameter leading to a) excessive pressure drop b ) partial or full disruption of flow c) pump operating point moving towards shut-off leading to reduced pump efficiency and accelerated mechanical wear and tear of the pump and pump sealing system.

Flow of Liquids (comprising of entrained heavier liquid with a lighter liquid):
A typical example would be a hydrocarbon liquid with entrained water, where the hydrocarbon liquid is the continuous phase while the water is the discontinuous phase. At low flowing velocities the entrained discontinuous phase water will drop out from the continuous phase hydrocarbon liquid to the bottom of the pipe. Water accumulation will occur in low points of the piping over a long term. If the hydrocarbon liquid has even trace amounts of dissolved carbon dioxide or hydrogen sulfide, pipe / pipeline corrosion can occur. The mechanism of corrosion in simplistic terms is that carbon dioxide and / or hydrogen sulfide will react with the accumulated water in the pipeline leading to acid corrosion by formation of Carbonic Acid (H₂CO₃) and / or Sulfuric Acid (H₂SO₄). Such corrosion can lead to failure of carbon steel piping / pipeline over a long term.

Single Phase Gas Flow (with entrained liquids):
A typical example would be natural gas containing entrained liquid droplets of water and heavier hydrocarbons. At low flowing velocities the flow would be stratified in the horizontal pipe, where the gas travels at the top of the pipe and the liquid travels at the bottom of the pipe and liquid accumulation occurs at low points and direction changes in pipe over a long period of time. The same problem of corrosion can occur as discussed for flow of liquids. Additionally, the gas transport could see high pressure drops and reduction in flow, putting excessive loads on gas compressors. Liquid accumulation over a long term in pipelines due to low velocities can also lead to intermittent slug flow in pipelines. The high momentum of liquid slugs can lead to structural damage of piping / pipelines and their supports.

Often natural gas pipelines have been found to have black powdery material (solids) in small amounts. The black powder could be because of corrosion products, trace amounts of solids carried over from gas treatment plants, mill scale etc. Low flowing velocities in gas transmission pipelines can lead to accumulation and deposition on pipeline walls of the black powder over a long-term and lead to excessive pressure drop and reduced flow. Flow velocities need to be kept above a threshold velocity also known as minimum entrainment velocity to prevent black powder deposits.

3-phase flow (Gas-Liquid-Liquid with Oil as continuous phase):
A typical example would be crude oil from reservoirs with associated gas (dissolved or free) and free water. Low flowing velocities will cause similar problems as discussed above related to corrosion. Additionally, if the crude oil is heavy crude oil containing asphaltenes, then reduced flow velocities (reduced flow) for a given pipeline will drastically increase the asphaltene deposition rate on the pipe walls. The long-term effect could be partial or total flow stoppage requiring costly cleaning operations for full restoration of pipeline operations.

Quantification of Minimum Velocities:
I had prepared a standard “Specification for Process Design Basis” for a middle-east oil & gas operating company wherein I had mentioned also about minimum velocities in pipelines. For unlined carbon steel pipelines transporting liquid hydrocarbons (light crude oil or condensate) containing free or entrained water even in a small quantity (e.g. 1% water cut), the velocities should not be allowed to fall below 1.5 m/s to prevent water dropout. For gas pipelines I had mentioned that the normal range of flow velocities should be 5 to 10 m/s. For bone dry gas, velocities up to 20 m/s may be allowed, subject to design considerations for noise and vibration prevention during all operational scenarios.

As mentioned earlier, black powder in natural gas pipelines will not be entrained at low gas velocities. This may lead to accumulation at some portion of the gas pipeline over a long duration. The entrainment velocity for these very fine particles is a function of their micron size. Generally, for a particle size of 1 micron to remain entrained, the gas velocity should be in the range of 2.5 to 4.5 m/s, depending on the pipe size.

Measures to prevent low velocities:
In intermittent or batch transfer operations, when demand is low at the receiving station, continue pumping at the same high rate as required for peak demand but for a shorter duration. There is no need to reduce the flow rate for low demand in batch transfer operations. Standard Operating Procedures (SOPs) should address such turndown or low demand scenario without reducing the flow and thus the velocity.

Measures to mitigate low velocities:
In continuous operations and prolonged turndown scenarios, low flow velocities are unavoidable. To prevent the aforementioned problems associated with low flow velocities, some measures that could be implemented are described below:
1. Injection of anti-corrosion and anti-scale additives in the piping / pipeline system.
2. Addition of emulsifying agents in liquid hydrocarbon-water systems to prevent phase separation occurring at low velocities.

Note: The addition of additives to prevent corrosion, deposits and phase separation should be carefully evaluated from the viewpoint of chemical compatibility with the process fluid and any adverse effects in downstream applications.

To conclude, low flowing velocities in pipes and pipelines can create problems such as corrosion, scaling and deposit formation and design and operational measures should be considered to prevent operations at low velocities.

I look forward to comments from members of “Cheresources”.

Regards,
Ankur.

Production Of Triple Superphosphate

Dec 26 2018 08:20 AM

Dear All,

Today's blog entry is in continuation of the blog entry I had made earlier for production of phosphoric acid using the wet process. The phosphoric acid produced by the wet process can be used as a raw material for the production of triple superphosphate.

The process description for Triple Superphosphate is referenced from Kirk-Othmer Encylopedia of Chemical Technology. the material balance is provided as an excel attachment to the blog entry.

Triple (Concentrated) Superphosphate. The first important use of phosphoric acid in fertilizer processing was in the production of triple superphosphate (TSP), sometimes called concentrated superphosphate. Basically, the production process for this material is the same as that for normal superphosphate, except that the reactants are phosphate rock and phosphoric acid instead of phosphate rock and sulfuric acid. The phosphoric acid, like sulfuric acid, solubilizes the rock and, in addition, contributes its own content of soluble phosphorus. The result is triple superphosphate of 45- 47% P₂O₅ content as compared to 16- 20% P₂O₅ in normal superphosphate. Although triple superphosphate has been known almost as long as normal
superphosphate, it did not reach commercial importance until. the late 1940s, when commercial supply of acid became available.

Simplicity of production, high analysis, and excellent agronomic quality are reasons for the sustained high production and consumption of TSP. A contributing factor is that manufacture of the triple superphosphate has been an outlet for so-called sludge acid, the highly impure phosphoric acid obtained as a by-product of normal acid purification.

Chemistry and Properties: TSP is essentially impure monocalcium phosphate monohydrate, Ca(H₂PO₄)₂ ·H20, made by acidulating phosphate rock with phosphoric acid according to:

The complete chemistry of TSP production has been studied and reported in great detail. As in the production of NSP also known as Single Superphosphate (SSP) there are also reactions with impurity minerals. The range of constituents in commercial TSP from wet-process acid and phosphate rocks are typically: Ca(H₂PO₄ )₂.H2O, 63-73%; CaSO₄, 3- 6%; CaHPO₄ and Fe and Al phosphates, 13- 18%; silica, fluoro silicates, unreacted rock, and organic matter, 5-10%; and free moisture, 1-4%. The average citrate solubility of the P₂O₅ in best quality TSP is 98-99%, but products with citrate solubility values a few percentage points lower are not uncommon. The P₂0₅ citrate solubility of TSP made by a quick-cure process is a ca 96%. Other common properties of TSP are bulk density, non-granular, 879 kg/m³; granular, 1040-1200 kg/m³; and critical relative humidity at 30°C, 94%.

Production Technology: Phosphate rock and wet-process phosphoric acid are the only raw materials required for manufacturing TSP. The grade of rock can be a little lower than that needed for NSP production. Over the years, a large number of process modifications, both batch and continuous, have been used. For the production of nongranular TSP, 52-54% P₂O₅ acid is used without dilution or heating. The P₂O₅:CaO mole ratio, including the P₂O₅ in the rock, is 0.92-0.95. The rock is ground to 70% <74.urn (200 mesh). Pile curing for a few weeks is typical, as for NSP.

Granular TSP (-6 + 16 mesh (1.19 to 3.35 mm dia)) is preferred for direct application and is used in bulk blend fertilizers. A widely used slurry granulation process is the Dorr-Oliver process. The ground rock is mixed with 38-49% P₂O₅ acid in a series of reaction vessels. Slurry from the reaction train then is mixed with a large proportion of recycled undersize granules and crushed oversize in either a pugmill or drum granulator. The granules are dried and screened. The product-size material is about 1 part in 13, thus the recycle ratio is 12:1. Other processes involve granulation of previously prepared nongranular TSP.

Economics: In contrast to NSP, the high nutrient content of TSP makes shipment of the finished product preferable to shipping of the raw materials. Plants, therefore, are located at or near the rock source. The phosphoric acid used, and the sulfuric acid required for its manufacture, usually are produced at the site of the TSP plant. As in the case of NSF, the cost of raw materials accounts for more than 90% of the total cost. Most of this is the cost of acid.

Since about 1968, triple superphosphate has been far outdistanced by Diammonium Phosphate as the principal phosphate fertilizer, both in the United States and worldwide. However, production of triple superphosphate is expected to persist at a moderate level for two reasons: (1) at the location of a phosphoric acid-diammonium phosphate complex, production of triple superphosphate is a convenient way of using sludge acid that is too impure for diammonium phosphate production; and (2) the absence of nitrogen in triple superphosphate makes it the preferred source of phosphorus for the no-nitrogen bulk-blend fertilizers that frequently are prescribed for leguminous crops such as soy beans, alfalfa, and clover.

The above paragraphs are edited from Kirk-Othmer Encyclopedia of Chemical Technology.

Also an excel workbook is attached providing some material balance calculations for Triple Superphosphate.

Comments and observations on this blog article are welcome.

Regards,
Ankur

Attached File(s)

TSP_Production_Flowsheet_and_Calcs.xlsx (193.14KB)
Number of downloads: 2209

Gas Turbine Power Re-Rating For Site

Sep 12 2018 01:55 PM

Dear All,

Gas turbines are important in the chemical process industry. They are often used as mechanical drivers for large centrifugal and reciprocating compressors which transport very large volumes of natural gas at high pressures over long distances.

Gas turbine vendors specify gas turbine power at standard conditions which are as per the "International Standards Organization" abbreviated as ISO. This is called the ISO rating of the gas turbine and is according to the ISO document ISO 3977-2:1997 Gas Turbines -- Procurement -- Part 2: Standard reference conditions and ratings.

Following are these conditions:

Ambient Temperature = 15 deg C
Altitude = 0 m (sea level)
Ambient Pressure = 101.325 kPa (abs)
Relative Humidity = 60%

The standard conditions also specify inlet and exhaust losses as zero.

What about actual site conditions where the gas turbine needs to be installed? Gas turbines need to be re-rated for actual site ambient conditions and also considering inlet and exhaust losses. Power and Heat Rate of the GT need to be re-rated on account of actual site conditions and inlet / exhaust losses. These require the application of correction factors to the ISO power and ISO heat rate of the GT. Today's blog entry provides the procedure for re-rating (de-rating / up-rating) the ISO power for the actual site and considering inlet / exhaust losses.

Some graphs and formulas are provided below to obtain the correction factors:

Power Correction factor for Altitude at Site (CF_alt)

Power Correction factor for Inlet Loss

where:
CF_inletloss = correction factor
PDi_nlet = Inlet Pressure drop, kPa
Note: The inlet pressure drop is in the range of 1 to 1.5 kPa (GT vendor can also provide this data)

Power Correction factor for Exhaust Loss

where:
CF_exhaustloss = correction factor
PD_exhaust = Exhaust Pressure drop, kPa
Note: The exhaust pressure drop is in the range of 0.5 to 1 kPa (GT vendor can also provide this data)

Power Correction factor for Ambient Temperature at Site

where:
CF_Tamb = correction factor
T_amb = Ambient temperature at site, ⁰C
Note: The correction factor for ambient temperature should be calculated for both minimum average ambient temperature and maximum average ambient temperature of the GT installation site and applied accordingly for re-rating the gas turbine.

After calculating the correction factors as above the site re-rated gas turbine power output can be calculated as follows:

GT Site Power = GT ISO Power*CF_alt*CF_inletloss*CF_exhaustloss*CF_Tamb
where:
GT Site Power = Re-rated GT Power at actual site, kW
GT ISO Power = Vendor Specified Power, kW

Gas Turbine Heat Rate re-rating has a similar approach and I will deal with that in my next blog entry. I would welcome comments from the members of "Cheresources" on my blog entry.

Regards,
Ankur.

Wet Process Phosphoric Acid Production Material Balance

Aug 12 2018 01:08 AM

Dear All,

Phosphoric Acid and the derived Phosphate fertilizers play an important role in any economy which has substantial dependence on agriculture. India happens to be one such country where agriculture contributes to approximately 17% of GDP and employs somewhat more than 50% of India's employment.

Although I have never directly worked in the fertilizer sector, I find this area of chemicals quite fascinating from a chemical engineer's perspective. Lately I had been doing some studies on production of wet phosphoric acid and the superphosphates. This led to my developing a material balance spreadsheet for wet phosphoric acid production from commercially mined phosphate rock which I am attaching with this blog entry along with the reference of the literature I have used for developing this spreadsheet. The spreadsheet also includes a process flow scheme for the manufacture of wet phosphoric acid. But before I share the spreadsheet a brief description of the process is essential. Here it goes:

Wet Process for Phosphoric Acid:

Phosphoric acid is produced from fluorapatite, known as phosphate rock, 3Ca₃(PO₄)₂.CaF₂, by the addition of concentrated (93%) sulfuric acid in a series of well-stirred reactors. This results in phosphoric acid and calcium sulfate (gypsum) plus other insoluble impurities. Water is added and the gypsum is removed by filtration along with other insoluble materials (e.g. silica). Fluoride, as H₂SiF₆, is removed at a further stage by evaporation. Although the reaction takes place in stages involving calcium dihydrogenphosphate, the overall reaction can be represented as:

However, there are side reactions; for example with calcium fluoride and calcium carbonate present in the rock:

Fluorosilicilic acid is an important by-product from this.

The crystal structure of the calcium sulfate formed depends on the conditions of the reaction. At 340-350 K, the principal product is dihydrate, CaSO₄.2H₂O. At 360-380 K, the hemihydrate is produced, CaSO₄._¹/₂H_₂O.

Calcium sulfate is filtered off and the acid is then concentrated to 56% P₂O₅ using vacuum distillation.

The product from the 'wet process' acid is impure but can be used, without further purification, for phosphatic fertilizer manufacture such as triple superphophate (TSP), Monoammonium dihydrogenphosphate (MAP) and Diammonium hydrogenphosphate (DAP). Alternatively it can be evaporated further to a concentration of 70% P_₂O_₅_, a solution called superphosphoric acid which is used directly as a liquid fertilizer.

In my subsequent blog entries I will come out with details of other phosphate fertilizers such as Single Superphosphate (SSP) and Triple Superphosphate (TSP).

The excel spreadsheet for material balance for wet process phosphoric acid (dihydrate) is attached. I would welcome comments on the spreadsheet either to point out improvements or any errors.

Regards,
Ankur.

Attached File(s)

Phosphoric_Acid_Production.xlsx (110.67KB)
Number of downloads: 2073

Spray Tower Scrubber Sizing For Flue Gas Desulfurization

May 02 2018 01:56 AM

Dear All,

Today's blog entry deals with the design and sizing of a non-packed spray tower for the purpose of flue gas desulfurization.

A spray tower sizing web resource is available on the internet which has been used as a basis for the design. However this sizing routine does not provide a clear cut method for determining the gas phase mass transfer coefficient and therein comes the research I had to do to arrive at a empirical method to determine the gas-phase mass transfer coefficient based on a reference document from the EPA (Environmental Protection Agency) of the United States..

References can be referred to from the attachments below:

88288739-Process-Design-of-Spray-Chamber-or-Spray-Tower-Type-Absorber.docx (476.25KB)
Number of downloads: 6906

9101DWOO.PDF_Dockey=9101DWOO.PDF (3.31MB)
Number of downloads: 6987

The gas-phase mass transfer coefficient K_Ga has been referred from the second attachment (refer page 37 for the equation). This equation is a direct method to calculate the gas-phase mass transfer compared to the method utilized in the first attachment where this value is obtained in an indirect manner by comparing with an existing spray tower with given dimensions, inlet / outlet SO₂ concentrations and lime circulation rate.

If you compare the values of the gas-phase mass transfer coefficient K_Ga calculated from the indirect method in the first attachment and the empirical equation from the second attachment (EPA report) they are quite close based on a lime circulation rate of 60 m³/h as considered in the first attachment.

Combining the sizing methodology of the first attachment with the gas-phase mass transfer coefficient equation from the second attachment, I have developed an excel workbook which sizes a spray tower. The circulation rate for the limestone solution is considered as 3 liters per actual cubic meter of flue gas which is again referenced from another EPA report. The value of the gas-phase mass transfer coefficient is in turn dependent on the circulation rate through the spray tower. Higher the circulation rate, higher the value of the gas-phase mass transfer coefficient. The reference details are provided in the excel workbook itself.

The excel workbook can be downloaded from the file library with a link from the blog entry here:

https://www.cheresou...rubbing-design/

I would appreciate comments from members of "Cheresources" on my blog entry and the excel workbook.

Regards,
Ankur

Product Blending - In-Line Blending From Tankage

Apr 18 2018 12:17 AM

Dear All,

It has been a good 6 months since my last blog entry. Just couldn't find the time and the right topic to post on my blog. But, I am back with a new topic. Let me have your comments and advice on this latest one.

Today's topic is about in-line product blending using sophisticated microprocessor controls and ratio algorithms. Many leading companies in industrial control and automation such as Emerson, Yokogawa, ABB can provide customized control solutions for product blending. Each of them can also provide consulting services for a optimized control solution for a given product blending application based on their prior experience.

My blog entry provides a basic introduction to in-line product blending and an attached basic flow diagram and control scheme for in-line product blending from tanks. The attachment uses the example of gasoline blending, which is one of the most widely practiced blending operations in refinery complexes. So here it goes:

In-Line Blending from Tankage - This blending method also requires the use of both component tankage and product tankage. However, the components are pumped simultaneously under flow or flow ratio control through a common blending header. The contents of the product tank are approximately on-specification at any time during the blending operation provided the flow ratios correctly reflect the current component tank properties. An in-line blending system from tankage is shown in the attachment. Each component is ratioed either to a master component on flow control or to a total blending rate signal. Analyzers provide both component and product properties input to an advanced computer blending control system which in turns control the various component flow rates. The blend quality control application calculates the component flow ratios (or component flows) required to meet blend header product quality specifications over the entire blend. Conventional on-line analyzers, such as octane engines (for RON and MON), RVP and distillation are suitable for blend quality control. However, more recently, FT-IR analyzers have been used. From strictly a blending standpoint, a single FT-IR analyzer is capable of monitoring multiple component streams as well as the finished product to allow the control system to make on-stream corrections during the blend operation to reflect minor changes in component qualities.

This type of blending system is frequently used for gasoline.

The following factors should be kept in mind when one is considering in-line blending from tankage:

1. Component tankage permits mixing and testing of components prior to blending. A minimum of two tanks per component is preferred. One tank is assigned for the blend and the other for production rundown. The tank assigned for the blend should be well mixed such that the component quality will not vary over the blend cycle. Provided component tank(s) are well mixed and isolated from production rundown, component qualities can be certified by lab analysis and periodic or continuous sampling is not required during blend operation. If blend component quality varies during blend operation (i.e. tank not well mixed and/or blend tank is not segregated from production rundown) on-line monitoring of component quality should be considered.

2. This type system is very flexible and permits minimizing product quality giveaway if components of appropriate quality are available.

3. Multiple grades per product and seasonal blend variations can often be handled sequentially through one blending header, thereby minimizing blender investment.

4. Tankage requirements to cover working and turnaround requirements may be split between blendstock
components and finished product tankage. Consistent with the concept of minimizing total tankage, component storage is preferred to finished storage since it provides better flexibility to blend multiple finished products.

5. With accurate component flow/ratio control, the blend may be considered "on-spec” as soon as all components are mixed in the blending header. Thus, while the blending is in progress, sampling of this header will permit blend evaluation and fine point blend corrections to optimize the blend. Furthermore, this technique will result in multiple sampling and testing leading to reduced standard deviation for the blend which, in turn, results in much greater test accuracy/reliability and further blend optimization.

Refer the attachment for the flow scheme and control system for the in-line blending system. Some advantages are also mentioned for an in-line blending system in the attachment.

Look forward to comments on the blog entry.

Regards,
Ankur.

Attached File(s)

Gasoline_Blending_PFD.xlsx (50.8KB)
Number of downloads: 990

Steam Tracing Design

Nov 04 2017 12:54 PM

Dear All,

It is well known that chemical process plants located in areas where ambient temperatures can fall well below freezing may require heat tracing of lines and equipment containing process fluids that can freeze or congeal and stop flowing thereby causing costly plant outages and economic losses. In certain cases, freezing of line contents and flow blockage (total or partial) can result in accidents, such as rupture and release of hazardous chemicals from piping or equipment, endangering human life and the surrounding environment.

Well designed heat tracing systems will ensure that the possibility of freezing and blockage is minimized or eliminated. Universally two methods of heat tracing are practiced, electric or steam tracing. In many chemical process plants you will find a combination of both electric and steam tracing depending on the tracing application. In general, both specific application and the economics of electric or steam tracing will govern the choice of heat tracing. The design engineer will have to study both the applicability and the CAPEX / OPEX to decide the type of heat tracing suitable for the given system.

Today's blog entry specifically deals with heat tracing of using steam. An excel workbook is attached addressing the following:

1. Steam Tracer Sizing Tables: Given the process piping size, the selected tracer material (copper or CS) and the temperature to be maintained in the pipe to prevent freezing, these tables provide the number of tracers, recommended tracer tubing / piping size and the recommended steam flow rates per 100 m of tracer length.

2. Tables for Maximum Tracer length between Traps: These tables provide the maximum length of tracer, at the end of which a steam trap is needed, given the steam flow rate per 100 m of tracer length, and the steam inlet pressure to the tracer.

3. Table for maximum steam flow rate for different steam pressure levels and corresponding steam header size, based on economic pipe sizes, and for steam tracing application.

I am hoping that this workbook for steam tracer sizing proves useful to engineers who wish to design steam tracing systems. I look forward to comments from the members of "Cheresources". That is all for today.

Regards,
Ankur.

Steam_Tracing_Design.xlsx (42.78KB)
Number of downloads: 2638

The Perennial Debate On Piping / Pipeline Design Pressure

Oct 16 2017 11:09 PM

Dear All,

I have lost count on how many times I have debated and argued the topic of piping / pipeline design pressure. “Cheresources” itself has dozens of posts related to this topic. I am now a firm believer that most problems do not have one unique solution in context of process design. You could have multiple design approaches each with its own merit and demerit and the process engineer needs to adopt the design solution as per the demand and need of the end-user. However, whenever a process design engineer puts forward a design solution he or she should know all the pros and cons of the solution he or she is proposing, and assess its suitability for the end-user, or plant operator from all aspects such as safety, operational ease, design life and the economics of the proposed solution.

Let us move on to the topic of piping / pipeline design pressure. There are two major approaches in deciding or finalizing the design pressure.

1. Shut-off based design pressure for centrifugal machines. This is specifically true for centrifugal pumps. For centrifugal compressors, this is somewhat tricky, since you need to determine the design pressure based on surge limit curve on the overall compressor curve. A simplified approach in determining the design pressure at the preliminary design stage would be to add up the maximum suction pressure of the centrifugal pump or compressor with the normal differential pressure at the rated flow times some margin (1.25 or 1.3). This approach of determining the design pressure for piping in discharge of centrifugal machines is commonly employed in design practices of many engineering or operating companies. This normally works fine for centrifugal machines.

How about positive displacement machines? These are constant volumetric flow machines and even if you block the discharge the machine will keep on pushing a constant volume in the connected discharge pipe. The consequence would be a rise in pressure with blocked outlet eventually leading to the motor driver of the PD machine stalling and / or discharge piping damaged (ruptured / distorted). As such, there is no real concept of shut-off head or pressure in PD machines since the pressure will keep on building up till either the motor stalls and / or the pipe or flange gasket ruptures. Thus, the approach adopted in the aforementioned paragraph for design pressure of centrifugal machines is not likely to work in case of PD machines.

PD machines discharge systems are protected by pressure safety valves (PSVs) set at such a pressure that it will protect the entire discharge piping system including pipe and other components in the discharge system from damaging overpressure. Providing the set-pressure for the PSV requires a different approach. There could be multiple PSVs protecting various sections of the discharge system with a common design pressure and set at that pressure. If equipment in the discharge system has a lower design pressure rating, PSV could be provided for that individual equipment with its set pressure equal to the equipment design pressure. Another approach could be to fully rate the discharge system, which means that the entire discharge system including piping and connected equipment would have the same design pressure throughout the system. Fully rating the system and minimizing block or isolation valves in the discharge system would allow to provide minimum number of pressure relief devices.

It is important to note that, if a blocked-in scenario between two isolation or block valves can be justified for a section of the liquid full discharge system, it would be essential to provide a pressure relief device for thermal expansion for that section. The key to this statement is liquid full. It does not apply for gas filled pipe sections that can be isolated.

2. Design pressure based on pipe pound rating class and using the pressure-temperature rating as provided in ASME B16.5 (formerly ANSI B16.5). For new engineers ASME B16.5 is the American standard for “Pipe Flanges and Flanged Fittings”. Although the standard is an American standard it has found universal acceptance in piping design and engineering. The basic premise of deciding the design pressure as per ASME B16.5 is that a flange is the weakest joint in any piping system and this is universally true, that the strength of any system depends on the weakest component in the system. I personally find this a more appropriate approach for assigning a design pressure value of any piping system based on a given design temperature.

ASME B16.5 has extensive tables for pressure rating against a given temperature for various pipe pound ratings and various pipe materials of construction. Pound ratings start from 150# and go up to 2500#. Material classes are designated with numbers starting from Material Class 1.10 to 1.18, Material Class 2.1 to 2.12, and Material Class 3.1 to 3.19. Interpolation can be done for temperature values between two temperature values given in the tables.

Let us take an example:

Pipe pound rating: 300#
Material Class: 1.1 (This material class in general defines carbon steel material)
Design temperature: 80°C
Design Pressure: 47.6 barg (calculated from ASME B16.5)

The Pressure-temperature rating for Material Class 1.1 in B16.5 is the first table. It gives a pressure rating of 50.1 barg corresponding to a temperature rating of 50°C and a pressure rating of 46.6 barg corresponding to a temperature of 100°C. If we interpolate for 80°C, the corresponding pressure would be 47.6 barg.

If I must provide a PSV on the 300# piping with material class 1.1 for blocked-in conditions and hydraulic expansion of trapped liquid in this pipe or pipeline, commonly referred to as a “Thermal Relief Valve” or “Thermal Expansion Relief Valve”, I would give it a set-point of 47.6 barg.

This approach for assigning a design pressure would be good even for a centrifugal pump because it provides you flexibility in operations. For example, most centrifugal pump manufacturers would provide an option of 3 different impellers with different flow versus head curves for the 3 impellers. If for operational flexibility reasons, an impeller is changed to have a higher differential head, then any pressure relief devices which were originally provided with a set pressure based on design pressure calculated based on shut-off pressure for the rated impeller, would be of no use and would require the PSV to be reset for a higher set pressure for the changed (higher differential head) conditions.

I consider it to be a good engineering practice to fully rate the pump discharge piping system (including pipe, fittings and equipment) which means that the design pressure is the same throughout the piping / pipeline from the pump discharge. There may be arguments about the high cost of having a fully rated system, but it is important to remember that any failure has its own cost in terms of personnel safety, environmental hazards and lost production which in most cases would be higher than having a fully rated system. Not having a fully rated system would also require detailed failure mode and effects analysis study to determine what additional safeguards are required to protect the integrity of the system.

Although I have categorically mentioned my preference for fully rated piping / pipeline systems, the industry practice for oil / gas flow lines from well heads is not to fully rate them downstream of the choke valve. The cost of fully rating the long distance flow line based on choke valve upstream would be astronomical. SIL rated “High Integrity Pressure Protection Systems” (HIPPS) are employed to protect the flow lines downstream of the well head choke valve in case high pressures are encountered due to choke valve failure. API 14C provides recommendations for providing safety systems in upstream oil / gas installations including well head flow lines.

I have discussed enough on this topic for today and the it is open for discussions and comments from members of “Cheresources”.

Regards,
Ankur.

Thermal Profiling Of Long Distance Pipelines Carrying Chemicals (Gas And Liquid)

Sep 10 2017 04:17 AM

Dear All,

One of the important tasks while doing a pipeline process study is to do a thermal profile study of a pipeline for various operating scenarios and ambient conditions. However, what are the practical aspects of doing a thermal profile are mostly unknown to majority of new engineers who undertake this exercise. In fact many young engineers are not even aware that a thermal profile for the pipeline needs to be developed to understand the problems that can occur in pipeline transport.

Let me first list down some problems related to thermal effects in a long distance pipeline:

1. For a gas pipeline frictional pressure drop in the pipeline can lead to Joule-thomson cooling in the pipeline which is an isenthalpic process. It is possible that flowing gas temperatures over a certain pipeline length may fall below the hydrate formation temperature of the pipeline gas, which can lead to ice crystal formation in the pipeline, which in turn can lead to pipeline flow disruption by partial or full pipeline blockage. In a worst case scenario, this can lead to a pipeline rupture with loss of property and human lives. Gas hydrate formation is favored by high pipeline pressures, and already low transportation temperatures such as in deep sub-sea pipelines. Thus a thermal study becomes absolutely essential to determine whether such an event can occur and what mitigative measures need to be taken.

2. Depressurization of gas pipelines during emergency or routine maintenance operations is another issue which needs attention in terms of thermal study of the depressurization operation. Adiabatic depressurization can lead to extremely low temperatures at the depressurization source, and immediately downstream of the depressurizing device (valve or orifice). Ordinary carbon steels can suffer catastrophic brittle fracture at very low temperatures compromising pipeline safety. Normal commercial carbon steel grades often used for fabricating pipe such as ASTM A 106 and ASTM A 53 are not designed for temperatures below -29 deg C. In process engineering terms the pipe needs to be categorized for its "Minimum Design Metal Temperature" abbreviated as MDMT. Among carbon steels ASTM A333 Gr. 1 and Gr.6 are suitable for low temperature service up to -45 deg C and are impact tested for that temperature.

A thermal study of the depressurization process can provide the lowest temperatures that a pipeline can see, and thus define the MDMT of the pipe material. As an example, if a depressurization thermal study indicates that the temperature of pipeline can fall below -29 deg C, the material specialist is most likely to suggest to go for "Low Temperature Carbon Steel" abbreviated as LTCS along with a brittle test for the pipe material known as "Charpy V-Notch Impact Test" to determine the brittleness of the material at low temperatures. If the depressurization thermal study indicates temperatures falling below -46 deg C, and up to -80 deg C, thus further lowering the MDMT of the pipe material, then the material specialist may further require to upgrade the metallurgy to Duplex Stainless Steel (DSS). Cryogenic temperatures either during normal operation or maintenance tasks, may require selection of austenitic stainless steels. Again this would be determined by thermal studies of the process system.

3. Pipelines transporting crude oils, specifically highly viscous and with high asphaltene content, require a thermal profiling to determine whether the pipeline temperatures fall below the pour point or not along the pipeline length. Possible pipeline blockages due to temperatures falling below pour point can lead to production disruption, expensive cleaning, dechoking operations, and heavy economic losses. Based on the thermal profiling and determination of lowest temperatures in the pipeline, remedial measures can be taken to prevent such an occurrence.

4. Transportation of LPG (propane and propane:butane mixtures) in pipelines is another area which requires particular attentions in terms of thermal studies of the pipeline. Exposure to high ambient temperatures for above ground pipelines or sections of above ground pipelines of LPG require a careful thermal study, to ensure that the LPG does not vaporize in the pipeline at the operating pressure,which can lead to vapor locking and 2-phase flow at the determined temperature. At the destination end of the pipeline, if there is a flow or pressure control valve, and due to temperature rise of the LPG along the pipeline length there is partial vaporization at the inlet of the control valve leading to inlet 2-phase flow, it is very detrimental for the operation of the control valve in terms of valve integrity. In a nutshell, it is absolutely undesirable to have 2-phase flow in a LPG pipeline, and a thermal study would indicate, whether such a phenomena occurs across the length of the pipeline from the source to the destination.

However, when doing such thermal studies for above ground pipelines exposed to the ambient atmosphere it is absolutely essential that realistic ambient conditions are used as inputs. To put this in perspective, a good designer would consider average high or low ambient temperature conditions and average high or low wind speeds over a time duration (say summer / winter or 1-year average conditions) rather than one-off high or low temperature and wind condition values which are highly unlikely to re-occur. To put it somewhat crudely, freak weather values of temperature and wind velocities should not be used for thermal profiling of pipelines exposed to the ambient. Using such freak ambient conditions may have a huge economic cost, which may not be justified for normal pipeline operating conditions. Abnormal ambient conditions would actually dictate that pipeline operation be stopped or curtailed.

5. There are many pipeline and process simulation software that can perform thermal studies / profiling of pipelines. Obviously, software dedicated for pipeline simulation such as PIPESIM, PIPEPHASE, PIPELINE STUDIO, AFT, OLGA would be the best bet for performing such thermal studies. But general process simulation software such as Aspen HYSYS, UniSim, Aspen Plus are also capable of performing thermal profiling of pipelines with certain limitations. Aspen HYSYS has a very nice "Depressurization" utility which can provide thermal profiles of any equipment or pipeline being depressurized. The key to using any such simulation software is that you exactly know what you need from the thermal study and provide the right inputs including checking the veracity of the default values the software uses for your particular study, and if required, to change those default values to suit your particular case study. In a nutshell, use the software as a process or chemical engineer and not as a data entry operator.

This is all for today folks. This has been a long blog entry but I hope you enjoy what I share with you and I look forward to your comments and observations.

Regards,
Ankur.

Actual Orifice Areas For Different Relief Valve Manufacturers Based On Api 526 Orifice Designations

Aug 29 2017 12:01 PM

Dear All,

API 526 provides provides orifice designations such as D, E, F..... etc. for relief valves with corresponding orifice cross-sectional areas. However, most manufacturers of relief valves provide the same API 526 designations with different areas (higher than as given in API 526) using a de-rated coefficient of discharge for the orifice. They call it the "actual orifice area" or "actual discharge area" which when de-rated with their own coefficient of discharge becomes equal to the API 526 orifice area.

In practice, if you are calculating the flow rate for a relief valve and specifically for the purpose of inlet / outlet line sizing and for fulfilling the inlet pressure drop criteria of 3% of set pressure and outlet line pressure drop of 10% of set pressure (conventional relief valve) then you must use the "actual orifice area" in the API 520 Part 1 formulas for flow rate for a given orifice as per the specific manufacturer.

Today's blog entry provides an excel table for the various reputed relief valve manufacturers across the globe whose "actual orifice area" is higher than the area as given in API 526 corresponding to the particular alphabetical orifice designation. This table should be useful if somebody selects a specific model of a given manufacturer such as "Farris" or "Leser". Not all manufacturers or models are covered but some more famous manufacturers and their common models are covered for the benefit of the members and readers of "Cheresources" and they can use it to determine the actual flow rates using formulas of API 520 Part 1.

It is important to note that this excel workbook does not include orifice areas as given in ASME Section VIII and covers only API 526.

Members and readers are welcome to provide their comments on the blog entry and the attached excel workbook.

Regards,
Ankur.

Actual_Orifice_Areas_API526_Type_PSVs_Vendor_Data.xlsx (12.36KB)
Number of downloads: 3040

Centrifugal Compressor Surge Control Schemes And Control Elements

Jul 09 2017 01:16 AM

Dear All,

I have written before on centrifugal compressor surge and anti-surge control. Refer my blog entry at the following link:

https://www.cheresou...-surge-control/

The above mentioned blog entry also provides an excel workbook for basic anti-surge control

In continuation of my further studies on surge control I have now prepared another excel workbook which provides variations in surge control schemes and also provides requirements and recommendations for the control elements used in centrifugal compressor surge control.

The basic source for these schemes and recommendations related to surge control is:
APPLICATION GUIDELINE FOR CENTRIFUGAL COMPRESSOR SURGE CONTROL SYSTEMS - Release Version 4.3 prepared as a guidance practice by Gas Machinery Research Council (Southwest Research Institute)

Some other open articles on the internet and company standards have also been referred to make the excel workbook more comprehensive.

The effort has been to provide information through bullet points against each item for ease of understanding.

I would appreciate comments from the esteemed members of Cheresources to enhance the workbook in terms of additional information and quality of information, specifically with respect to modern methods and tools for centrifugal compressor surge control.

The workbook is attached.

Regards,
Ankur

Centrifugal_Compressor_Surge_Control_Systems.xlsx (130.62KB)
Number of downloads: 1545

Descriptive Comparison Between A Centrifugal And A Reciprocating Compressor

Jun 02 2017 10:19 PM

Dear All,

It has been really a long time since I have posted a new entry. I was preoccupied with work and also did not find the right topic to post.

My fascination with compressors continues. I was reading some articles on compressors and this one particular article struck me to be quite interesting. The article gives a descriptive comparison between a centrifugal and reciprocating compressor. The article is titled as: "What's Correct for My Application - A Centrifugal or Reciprocating Compressor" authored by very distinguished compression equipment specialists: Paul Gallick - Senior Applications Engineer, Elliott Company; Greg Phillipi and Benjamin F. Williams of Ariel Corporation. The link for the article is given below:

http://turbolab.tamu.../15-GALLICK.pdf

The article provides descriptive comparison of a centrifugal compressor and reciprocating compressor on various parameters such as flow, pressure, efficiency, discharge temperature, materials of construction, cost etc.

I have presented the contents of the aforementioned article in an excel workbook template with minor changes here and there, based on various other sources and my own understanding of compressors. The idea was to make this comparison more compact and easier on the eye for engineers who would be interested to enhance their understanding of compressors.

The excel workbook is attached with this blog entry. I look forward to comments on the compilation I have done.

Regards,
Ankur

Comparison_Centrifugal_vs_Reciprocating_Compressor.xlsx (42.8KB)
Number of downloads: 2337

Pipeline Pig Launchers And Pig Receivers - Design Codes

Nov 19 2016 06:55 AM

Dear All,

After a long hiatus I am back on my blog. That the blog has crossed a milestone of 1.5 million views is a huge encouragement and I wish to thank the readers of my blog for such an overwhelming response.

Pig Launchers and Pig Receivers have been discussed many times on "Cheresources". However, I understood that there exists a confusion regarding the design codes to be applied for pig launchers / receivers. Today's blog entry tries to explain the design codes related to them and some rationale for them.

Older designs of pig launchers / receivers were based on the ASME Section VIII Div. 1 pressure vessel code. While these designs still exist and work, the modern design approach is to design them according to the connected pipeline or pipe code.

For fresh engineers new to piping / pipeline standards and codes, the following piping / pipeline codes and standards are followed almost universally. Some countries have developed their own standards which are also mentioned below:

1. ASME B31.3: which governs the design of process piping (code) (USA)
2. ASME B31.4 which governs the design of liquid pipelines(code) (USA)
3. ASME B31.8 which governs the design of gas pipelines (code) (USA)
4. ISO 13623:2009: Petroleum and natural gas industries - Pipeline transportation systems (standard)
5. BS EN 14161:2011: Petroleum and natural gas industries - Pipeline transportation systems (MODIFIED version of ISO 13623:2009) (standard) (European)
6. ISO 13703:2000: Petroleum and natural gas industries - Design and installation of piping systems on offshore production platforms (standard)
7. PD 8010-1:2015: Steel Pipeline on Land (code) (European)
8. PD 8010-2:2015: Subsea Pipelines (code) (European)
9. CSA Z662:2015: Oil and gas pipeline systems (standard) (Canadian)

API RP 14E: Recommended Practice for Design and Installation of Offshore Production Platform Piping Systems is a 1991 recommended practice and has not undergone a revision since 1991.

Among the aforementioned codes / standards the ASME codes are quite popular for pipeline / piping design.

Hence a pipeline designed as per ASME B31.4 should have a launcher / receiver designed as per the same code and a pipeline designed as per ASME B31.8 would have launcher / receiver as per the same code. In a rare case when a pipeline is designed as per ASME B31.3, this would apply for the launcher / receiver as well.

Designing a pig launcher / receiver as per PV code ASME Section VIII Div.1 does not make economic sense. Generally, given the same pipeline design parameters, a pig trap designed from ASME B31.3 will tend to be costlier than for one designed from ASME B31.4 or B31.8 because of the difference in material grades and thicknesses. In addition, a pig trap designed from ASME Section VIII Div.1 will tend to be more expensive than one designed from ASME B31.3 for the same reasons.

Normally a pig launcher / receiver for "liquid pipelines" which is designed as per pipeline code is provided a thermal expansion relief valve (TRV). This is to ensure its protection from overpressure due to thermal expansion of trapped liquid. For gas or two-phase fluid pipelines TRVs are not required.

Designing the launcher / receiver relief valve for external fire case is impractical although theoretically possible. In practice pigging is an intermittent operation and well planned and monitored. Before and after pigging operations it is ensured that the launcher and receiver are drained / vented to prevent any residual fluid inside. If a fire effects an empty launcher / receiver, the launcher / receiver will rupture even before the PSV designed for fire case pops at the set pressure. So practically it does not make a sense to have a PSV for fire case. Refer the link below for a very enlightening discussion on PSV on launcher / receiver. Specifically the post by don1980

http://www.eng-tips.....cfm?qid=360185

One of the reasons that engineers consider a PSV for fire case is because the pig launcher / receiver is designed as per pressure vessel code. If it were to be designed as per pipeline code then at the most for a liquid system launcher / receiver a TRV (for thermal expansion) may be provided which does not require any sizing calculations and providing a conventional 3/4 x 1" or 1"x 1-1/2" PSV would suffice. For single-phase gas or 2-phase fluid no PSV would be required.

Quick note from the admin: You can download the MS Excel workbook that accompanies this blog entry in the File Library.

That is all for today's blog entry. Look forward to comments and observations from the readers of my blog.

Regards,
Ankur.

Side Stream Filtration Rate For Cooling Towers

Jul 18 2016 02:38 PM

Dear All,

Suspended solids (particulates or turbidity) are frequently found in cooling towers. At best these suspended solids will tend to settle out in low velocity areas of the water system (such as the cooling water basin) where they can become a breeding ground for bacteria, requiring frequent cleaning and flushing of the basin. At worst, they can degrade system heat transfer capacity and lead to steep increase in dosing rate and consequently the cost of water treatment chemicals (e.g bactericides).

Modern day cooling tower systems have thus adopted side stream filtration of the water from the cooling tower. Various schemes can be implemented. The basin water inventory may only be filtered and / or side stream filters may be employed at the discharge of the CW recirculation pumps. Refer the simplified flow scheme of side stream filtration for a cooling tower:

When the side stream filter is employed in the discharge of the cooling water recirculation pump discharge, the flow rate required for filtration through side stream filter can be calculated by the following formula:

Side Stream Flow Rate, L/s = ((ppm suspended solids in recirculating cooling water / 200) - 1)*Blowdown Rate, L/s - Metric

Side Stream Flow Rate, gpm = ((ppm suspended solids in recirculating cooling water / 200) - 1)*Blowdown Rate, gpm - USC

From the above formula, it becomes obvious that if the ppm level of suspended solids is ≤200 ppm in the recirculation cooling water, side stream filtration may not be required. However, installation of side stream filter is recommended since suspended solid concentration builds up over time and periodic high build-up would require side stream filtration for the aforementioned reasons.

Pressure sand filters with backwash facilities are commonly employed as side stream filters for cooling towers.
Backwash water for the filters can either be from another source, or if cooling water is used, this water should be considered as part of the cooling tower blowdown. In either case, backwash effluent water must be sent to the waste water treatment plant.

That is all for today's blog entry. Comments are most welcome.

Regards,
Ankur.

Power Recovery Turboexpanders - Shaft Power Available

Jun 23 2016 04:29 AM

Dear All,

Commercial applications of high temperature power recovery turboexpanders use the expander to drive an air compressor which charges the process unit that produces the high temperature gas that expands to atmosphere across the turboexpander. The compressor/expander unit, together with its process unit, is therefore very similar to a special purpose combustion gas turbine engine cycle, with the process unit as the "combustion chamber."

Power recovery from Catalytic Cracker flue gases is one of the most important applications using turboexpanders in the petroleum refining field. FCCU Hot Gas Expanders are commercially available in speeds from 3600 to 7500 rpm, gas inlet conditions to 4.8 bara (70 psia) and 760°C (1400 deg F). Exhaust pressure is typically 1.24 bara (18 psia), mass flows range from 200,000-640,000 kg/h (440,000-1,410,000 Ib/hr). Power recovered ranges from 2600-37,300 kW (3500-50,000 hp). Units are typically 1 or 2 stages.

Today's blog entry provides the calculation for shaft power available from a power recovery turboexpander:

where:
η_i = Isentropic Efficiency. Use 85% for "as new" efficiency until specific vendor estimates are obtained. Assume an average isentropic efficiency 5% lower than the "as new" condition for economic studies that allow for erosion during a three year run.
η_m = Use 99%, allowing for bearing losses, and assuming no gear unit.
M = molecular weight of inlet gas, kg / kg-mol (lb / lb-mol). Assume value as 30.2 till specific flue gas analysis is available.
R = gas constant 8.31447 (1545) kJ / kg-mol.K (ft-lbf / lb-mole.⁰R)
W = Mass flow rate, kg/s, (lb/min)
T₁ = Inlet temperature, K (⁰R)
T₂ = Exhaust temperature, K (⁰R)
k = specific heat ratio; use 1.3 unless the flue gas analysis gives a better value
P₁ = gas pressure at expander inlet flange, kPaa (psia)
P₂ = gas pressure at expander exhaust flange, kPaa (psia)
Z = avg compressibility factor ((Z_in + Z_out) / 2)

Expander Exhaust Temperature:

The expander exhaust temperature is used to calculate the remaining flue gas heat which is still available for recovery by other means.

That is all for today. Hope to have comments and observations from members.

Regards,
Ankur.

Determining Potential Natural Gas Liquids (Ngl) In A Natural Gas Stream

Jun 04 2016 05:42 AM

Dear All,

The amount of potentially recoverable NGL based from a natural gas stream can be estimated from the following formula:

Potential NGL component (tons per annum) = V*y*CF
where:
V = Volume flow rate of natural gas, MMSm³/day (Std conditions are P= 1.01325 bara, T = 288.15K)
Note: MM= Million
y = mole percent of the component in natural gas
CF = Component factor (see table below)

Example: 3 MMSCMD of NG is available for processing. This gas contains 5.4% mol propane. What is the potential propane recovery from the NG?

Calculations:
Potential Propane Recovery (w/o Recovery factor and plant on-stream factor) = 3*5.4*6800 = 110160 t/a

Considering a plant recovery factor of 70% and plant on-stream factor of 335 days, the average propane recovery per annum would be:

110160*0.7*(335/365) = 70,770 tons per annum (t/a)

That is all for today. Any comments are welcome.

Regards,
Ankur.

First Approximation Of Fuel Gas Consumption For Gas Turbine Driven Compressor Station

May 14 2016 11:46 AM

Dear All,

A lot of us are required to do preliminary utility estimation calculations during the Feasibility / Concept stage of a project. Another terminology often used is the Pre-FEED stage of a project. In fact this is often where non-availability of data or insufficient data becomes a bottle-neck. In such cases some minimum data with certain empirical calculation methods help to arrive at figures which may be used to for high end (+/- 30%) cost estimation of a project and help establish its feasibility.

Today's blog entry as the subject line says, is with regards to compressor stations, for transport of natural gas through long-distance pipelines. An approximation for fuel consumption can be done using certain empirical formulas. The formula is presented herewith:

F = (14 / NHV)*(P_turbine + P_auxiliary)

where:
F = Fuel Gas consumption of the compressor and the auxiliary systems associated with the compressor, Sm³/h
NHV = "Net heating Value" of the Fuel Gas to be used, MJ/Sm³ (eg: Natural Gas ~ 41 MJ/Sm³ with a certain composition)
P_turbine = Turbine power requirement, kW
P_auxiliary = Power consumption in kW of auxiliaries associated with the compressor package, which includes electricity, lubricating oil system, cooling system etc.. This has a strong dependency on local climatic conditions and on the extent of gas sourced power used for such auxiliaries.

Note: Sm³ refers to standard cubic meter at standard conditions of temperature (15 deg C ) and pressure (101.325 kPa (abs))

That is all for today folks. Look forward to comments from your side.

Regards,
Ankur

Solid-Liquid Mixing In Agitated Vessels (Just Suspended Speed)

Apr 08 2016 06:29 AM

Dear All,

Solid suspension and dispersion in a liquid is an important operation carried out in mixing systems. The primary objective of solid-liquid mixing is to create and maintain a solid-liquid slurry, and to promote and enhance the rate of mass transfer between the solid and liquid phases. Such processes are typically carried out in mechanically agitated vessels and reactors. In agitated vessels, the degree of solids suspension is generally classified into three levels: on-bottom motion, complete off-bottom suspension, and uniform suspension. Refer the sketch below. For many applications, it is often important just to provide enough agitation to completely suspend the solids off the tank bottom. Below this off-bottom particle suspension state, the total solid-liquid interfacial surface area is not completely or efficiently utilized. Therefore, it is important to be able to determine the impeller agitation speed, N_js, at which the just suspended state is achieved by the particles.

Correlation for Just Suspended Speed:

where:
N_js = minimum impeller speed to just suspended solid particles in vessel, rps
S = Zwietering constant
ν = Kinematic viscosity of the liquid, m²/s
g_c = gravitational constant = 9.81 m/s²
ρ_s = denisty of solid particle, kg/m³
ρ_l = denisty of liquid, kg/m³
X = mass ratio of suspended solids to liquid or solid loading'=kg of solids / 100 kg of liquid
D = Impeller diameter, m

Table for Zwietering Constant (S):

Snapshot of an Example Problem in Excel:

This concludes today's blog entry. Would to receive comments from the learned members of "Chereosurces"

Regards,
Ankur.

In-House Software Validation - An Iso 9001 Perspective

Mar 12 2016 12:16 PM

Dear All,

Many of the engineers working in engineering consulting organizations know that a lot of in-house engineering calculation templates are utilized for equipment sizing, rating and other engineering applications.Many commercial software are also utilized in such organizations involving lease-and-license agreements with suppliers and developers of such software.

But what many engineers are not aware that if your organization is ISO 9001:2008 (Quality Management Systems-Requirements) compliant or is desirous to acquire an ISO 9001 certification then part of the compliance to ISO 9001 requires that the in-house developed software is validated. What does the term "validated" mean? Today's blog entry talks about validation of in-house software.

Please note that commercial software, for example simulation software such as ASPEN PLUS, ASPEN HYSYS, HTRI, PIPESIM do not require validation by the end-user. The validation for such software is the responsibility of the developers and licensors of such software and not the end-user. Many a times the technical term "Firmware" is used for such software which means it is a permanent software programmed into a read-only memory and cannot be altered or modified by anybody except the developers of the software.

The best definition I could find for validation is as follows:

"To establish the soundness, accuracy, or legitimacy of"

In context to this blog entry it means to establish the soundness, accuracy or legitimacy of the in-house engineering calculation templates. The question then arises that how to validate these calculation templates and let me assure you that it is a very simple task. Having said that, a task is a task and needs effort and time to accomplish.

What needs to be done? Since I personally have been involved in such validation procedures, I can provide a very simple explanation on how to proceed for validating in-house software.

MS-Excel is one of the simplest and most effective calculation software tool for in-house engineering calculations and most organizations subscribe to using Excel as a tool of choice for developing engineering calculations. Many of the engineers who subscribe to "Cheresources" for knowledge sharing and guidance are well versed with calculations done in excel spreadsheets.

A good calculation template will have a logical progression in steps for calculations, wherein the input data will be defined sequentially and the outputs will be generated in terms of numerical values for the desired parameter based on certain equations and formulas. However, the standard norm for excel calculation templates is to protect the output cells which contains formulas and only allow the input cells to remain unprotected. Essentially, the excel worksheet or workbook needs to be password protected to prevent inadvertent changes in the equations and formulas leading to erroneous results. When an excel worksheet is protected the formulas do not remain visible and the user does not know the formula used unless it is separately defined in the worksheet using for example Microsoft Equation 3.0. I personally follow the practice of defining the equations to ensure complete unambiguity. Even if the formula is visible, the source or reference of all the formulas is rarely mentioned in order to make the spreadsheet less complicated and cumbersome.

The spreadsheet or workbook calculation template as prepared above by any engineer in his organization and used to generate information for clients and 3rd parties is not validated. This has to be validated if ISO 9001 compliance has to be met. Let us proceed on how to validate this calculation template in a manner where it not only is ISO 9001 compliant but makes any new engineer very comfortable to use it without having doubts about its correctness and legitimacy.

In earlier days all engineering calculations were done on paper (engineering record sheets) using a blue or black pen. These engineering record sheets had a "Prepared", "Checked" and "Approved" block on every sheet where the initials and / or signature of the preparer, checker and approver were to be printed by pen. To validate your in-house excel worksheet you need to do the same.

Use a live calculation from an existing or archived project. Write down all the inputs required for the calculations, the formulas used and their source and /or reference in the engineering record sheets. For complex arithmetic or algebraic calculations break it down into two or more steps (which is generally not required in excel spreadsheets). Attach hard paper copies of the source and / or references to the calculation record sheets as annexures. Highlight the formulas, equations or sentences / paragraphs in the annexures for sake of clarity and ease.

Once the person who has prepared the paper document is through with his task, this paper document will pass to the "Checker" for checking. After due diligent checking, corrections, if any, will be done by the engineer who has prepared the document. If corrections have been done, it will undergo a 2nd check by the checker. Once the checker clears the document, it will move to the approving authority. A diligent approving authority will do a careful scrutiny of the paper document, and on finding any errors or misses, will discuss with the preparer and the checker. If required, other specialist engineer(s) may be involved in the discussion to resolve any differences of opinion. Once a consensus is reached on the correctness of the document including an exact match of the calculated outputs with those in the excel workbook, the validation paper document becomes final, and the preparer, checker and approving authority will print their initials / signatures on the paper document. This paper document will have to be filed diligently by the department quality representative with complete traceability. Traceability means that it is a numbered (alpha-numeric or numeric) document as per the numbering system adopted in the department quality work procedure or work instructions belonging to the organization ISO 9001 QMS.

This completes the validation procedure.

In addition, a supplementary MS-Word document with may be prepared which provides step-wise English language instructions on data entry in the excel calculation template. This would be specifically useful when calculations are long and complex and require elucidation in simple English. This word document could also be attached as an annexure to the main calculation hand printed paper sheets.

What happens if I don't validate? Very simply, any ISO 9001 auditor who audits the department quality management systems, has it in his rights, to give a "Non-Conformance Report" (NCR) for a not validated in-house software used for business purposes (projects), and demand a "Corrective Action Request" (CAR) report from the Department or Company Management Representative (MR). It means, that the CAR gets closed only when the validation document is prepared, is traceable, and easily retrievable.

Too many NCRs and CARs put a question mark on the effectiveness of the quality management systems of the organization and ultimately reflect badly on the organization.

In today's blog entry I have tried to explain briefly how you can validate your in-house engineering calculation templates. I hope many of you will ask questions and initiate a debate on such an important activity.

Regards,
Ankur.

Heat Transfer In Buried Liquid Lines (Stagnant Liquid)

Feb 13 2016 01:42 PM

Dear All,

My earlier blog entry on heat transfer in buried liquid pipelines related to temperature reduction of the flowing liquid at a certain distance from the pipeline inlet.

Let us think of a buried pipeline or pipeline section where the liquid flow has been stopped and the liquid is now in a stagnant condition in the pipeline or pipeline section. Let us consider that the time at which the pipeline or pipeline section contents are completely at rest (stagnant) is zero i.e, t = 0 seconds. Now let us say that the average temperature of the stagnant liquid at time t = 0 seconds is T₀, degrees C. If T₀ is higher than the surrounding (soil at pipeline burial depth) temperature than it will start decreasing with time due to heat transfer from the stagnant liquid in the pipeline to the surrounding. We want to know the drop in temperature of the stagnant liquid after a given time period of the stagnant liquid. In other words, we are required to calculate the temperature T_t at a time interval of t = t seconds. The unit seconds are used because the equations require the unit of time as seconds. From a practical point of view a realistic temperature drop will occur in hours or days and time in hours or days needs to be converted into seconds.

Today's blog entry provides the relevant equations for a fair approximation of the temperature drop of a stagnant liquid (no flow) in a buried pipeline. These equations can be used with a fair degree of accuracy for heavy crudes being transported in buried pipelines within the constraints of the value of the empirical constant 'β' selected in the range provided. Let us go to the equations:

where:
T_S = soil temperature at pipeline depth, K
T_t, T₀ = oil temperature at time t and 0 respectively, K
F = dimensionless 'Fourier' number

where:
λ = thermal conductivity of liquid, W/(m-K) (for crude oil, λ = 0.13 W/m-K)
t = time, s
ρ = oil or liquid density, kg/m³
C_p = specific heat capacity of liquid, J/(kg-K)
d = pipeline internal diameter, m

β = empirical coefficient (ranges from 6 to 10), depending on heat transfer in the soil around the pipe, the pipe coating, pour point of the liquid and wax layer on pipe wall. A higher value of β means higher thermal conductivity of these layers.

Specific Heat Capacity of Crude Oil

where:
C_p = Specific heat capacity at temperature T₀, J/kg-K
T₀ = Temperature, ⁰C
ρ = crude oil density at temperature T₀, kg/m³

A snapshot of an example calculation in an excel workbook is shown below to give an idea of the temperature drop at time t or in other words the numerical value of T_t.

That is all for today. Would be happy to have comments from members of "Cheeresources".

Regards,
Ankur.

Natural Gas Teg Dehydration Unit Troubleshooting

Jan 22 2016 02:01 AM

Dear All,

Today's blog entry is dedicated to my dear departed father who passed away to his heavenly abode on January 05, 2016. He was a man of literature and whatever little writing skills I possess, it was he who inspired and encouraged me. I guess, I inherited a bit of writing skills from both of my parents, my father being a poet and short-story writer and my my mother (still an active writer at 77 years of age) a novelist and a story writer.

Any natural gas processing installation is normally bound to have a gas dehydration unit for the purpose of removal of associated water and dew-pointing it to pipeline sales gas specification. In the United States, sales gas transmission pipelines have water specifications of a maximum of 7 lb per MMSCF, while in Canada it is <= 5 lb per MMSCF Dehydration using TEG as a liquid desiccant is the most common and economical means of bulk water removal from natural gas. Thousands of TEG dehydration units have been installed worldwide since the first TEG dehydration unit built in the early part of the 20th century. Natural Gas TEG dehydration is a mature technology and standard configurations are available for a wide variety of wet natural gas compositions.

The purpose of this blog entry is to provide a brief troubleshooting checklist which can prove useful to TEG dehydration unit field operators and maintenance personnel. While the attached checklist does not proclaim to be the one-and-all troubleshooting guide for TEG dehydration units it certainly gives an overview of the most commonly encountered problems and the general checks and actions required to eliminate them. The checklist does not substitute the experience of seasoned operators and maintenance personnel who have had years of operating and troubleshooting experience of TEG dehydration units.

The checklist is attached as both as a picture file and an excel workbook.

I hope to receive some comments and observations from the learned members of "Cheresources".

Regards,
Ankur.

Attached File(s)

TEG_Dehydration_Unit_Troubleshooting_Checklist.xlsx (11.92KB)
Number of downloads: 2233

Heat Transfer In Buried Liquid Pipelines

Dec 14 2015 08:49 AM

Dear All,

Today's blog entry relates to heat transfer from liquids flowing in long-distance buried pipelines. When liquids have to be transported at relatively high temperatures, e.g. viscous crudes/products, temperatures and cooling rates can be determined using the following formulae:

where:
T_L = average temperature in cross-section of pipeline at distance L, K
T_s = soil temperature at pipeline depth, K
T_inlet = temperature at pipeline inlet (L = 0), K
U_eff = Effective Heat Transfer Coefficient, W/m²-K
d = pipe internal diameter, m
L = pipeline distance at which T_L is to be measured, m
m = mass flow rate of liquid, kg/s
C_p =Specific Heat Capacity of pipeline contents, J/kg-K

Calculation of U_eff

U_convective
For turbulent flow (Re > 4000)

For Laminar flow (Re < 2300)

where:
U_convective = Convective heat transfer coefficient, W/m²-K
λ_liq = liquid thermal conductivity, W/m-K (for crude oil, λ_liq = 0.13 W/m-K)
u = average liquid velocity, m/s
ρ = liquid density, kg/m³
d = pipe internal diameter, m
C_p = Specific Heat Capacity of pipeline contents, J/kg-K
ν = liquid kinematic viscosity, m²/s
g = acceleration due to gravity = 9.81 m/s²
α = thermal expansion coefficient, 1/K (for crude oil, α = 8*10^-4 K-1)
µ_b = bulk liquid viscosity, Pa.s
μ_w = liquid viscosity at wall temperature, Pa.s
T_b = bulk temperature, K
T_w = inside wall temperature, K

Notes:
1. The inside wall temp. (T_w) is generally assumed 2-3 degrees lower than the bulk temp. (T_b) in laminar flow
2. The bulk liquid viscosity (μ_b) and the liquid viscosity at wall temperature (μ_w) can be assumed same for turbulent flow thus reducing the term (μ_b / μ_w) to 1

Specific Heat Capacity of Crude Oil

where:
C_p = Specific heat capacity at temperature T, J/kg-K
T = Temperature, ⁰C
ρ = crude oil density at temperature T, kg/m³

U_wall

where:
U_wall = steel wall heat transfer coefficient, W/m²-K
λ_steel = thermal conductivity of steel, W/m-K (for Carbon Steel, λsteel = 52 W/m-K)
d_o = outside diameter of the steel pipe, m

d = pipe internal diameter, m
t_wall = wall thickness, m

U_coating(Note: External Coating could be a polyolefin liner or insulation)

where:
U_coating = coating heat transfer coefficient, W/m²-K
d_o = outside diameter of the steel pipe, m
λ_coating = thermal conductivity of coating or insulation, W/m-K
t_coating = coating thickness, m

U_environment (For Buried pipes the environment is soil)

where:
U_environment = heat transfer coefficient to the environment (soil), W/m²-K
λ_soil = thermal conductivity of soil, W/m-K
z = burial depth of the pipe up to the pipe axis, m

I have developed a spreadsheet for temperature drop in a buried crude oil pipeline based on the above methodology. For a set of conditions that I have used and for a pipeline inlet crude oil temperature of 55⁰C, the temperature drops to 48.5⁰C at a distance of 50 km for a 16 inch NPS pipeline based on the above method. The pipeline is also externally coated.

That is all for today's blog entry. Hope to have comments from the knowledgeable members of the forum.

Regards,
Ankur.

Deoiling Hydrocyclones And Their Performance Prediction

Nov 12 2015 02:48 PM

Dear All,

Today's blog entry relates to liquid-liquid hydrocyclones used in produced water treatment in the oil & gas industry.

The static hydrocyclone has rapidly been accepted as a compact and efficient means of removing dispersed hydrocarbons from water. The basic design of the static hydrocyclone is illustrated schematically in the figure below:

The water containing the dispersed hydrocarbons enters the hydrocyclone through a tangential inlet atthe top of the swirl chamber. As the liquids swirl along the hydrocyclone, the centrifugal forces genarated promote the separation of the hydrocarbon and water phases, with the hydrocarbon phase forming a thin core at the centre of the hydrocyclone.

By maintaining a suitable pressure ratio between the clean water outlet stream and the reject oil outlet stream, the geometry of the hydrocyclone will result in the thin hydrocarbon core flowing in a reverse direction, exiting from the top of the swirl chamber. The clean water exits from the tail section of the hydrocyclone.

The following definitions are commonly used for hydrocyclones:
Feed: The oil water stream entering the hydrocyclone
Underflow: The clean water stream exiting from the tail of the hydrocyclone
Reject Stream or Overflow: The concentrated hydrocarbon stream exiting from the head of the hydrocyclone through the reject port
Reject Ratio ®: The ratio of the reject and feed stream volumetric flow rates (R = Q_reject / Q_feed)

Performance Prediction:
Cut Size Diameter:
The cut size diameter is a droplet diameter which can be used to characterize the separation performance of a hydrocyclone.

A common cut size diameter definition is the 50% cut size d₅₀.This is defined as the hydrocarbon droplet diameter which has a 50% probability of leaving the hydrocyclone in the reject stream and a 50% probability of leaving the hydrocyclone in the water outlet stream i.e.if

n_{d, reject} / n_d,out = 1 then d = d₅₀

Another commonly used cut size is d75, representing the hydrocarbon droplet size with a 75% chance of being removed from the water stream.

Cut Size Diameter Correlations:
Several correlations are available for the prediction of the droplet cut size. The following correlations are presented:

Bradley Equation:

d₅₀ = 0.053*D_cycl*(ρ_c / (Re_i*Δρ))^0.5

where:
d₅₀ = droplet size diameter as defined above, m
D_cycl = Diameter of the cylindrical hydrocyclone chamber, m
ρ_c = Density of the continuous phase (water), kg/m³
Δρ = Density diff. between the continuous phase (water) (ρ_c) and the dispersed phase (oil) (ρ_oil), kg/m³
Note: The min. recommended density difference for a hydrocyclone is 50 kg/m³ @operating temperature

Re_i = D_i*V_i*ρ_c / μ_c

where:
Re_i = Reynolds number at the hydrocyclone inlet, dimensionless
D_i = inlet diameter at hydrocyclone inlet, m
V_i = Fluid velocity at inlet, m/s
μ_c = viscosity of the continuous phase (water), kg/m-s

Rietema Equation:

d₅₀ = 0.51*D_cycl*[ρ_c / ((Re_i)^1.375*Δρ)]^0.5

where:
d₅₀ = droplet size diameter as defined above, m
D_cycl = Diameter of the cylindrical hydrocyclone chamber, m
ρ_c = Density of the continuous phase (water), kg/m³
Δρ = Density diff. between the continuous phase (water) (ρ_c) and the dispersed phase (oil) (ρ_oil), kg/m³
Note: The min. recommended density difference for a hydrocyclone is 50 kg/m³ @operating temperature

Re_i = D_i*V_i*ρ_c / μ_c

where:
Re_i = Reynolds number at the hydrocyclone inlet, dimensionless
D_i = inlet diameter at hydrocyclone inlet, m
V_i = Fluid velocity at inlet, m/s
μ_c = viscosity of the continuous phase (water), kg/m-s

Coleman-Thew Empirical Model:

d₇₅ = (Hy₇₅*D_cycl ^3*μ_c / (Q*Δρ))^0.5
where:
d₇₅ = droplet size diameter as defined above, m
D_cycl = Diameter of the cylindrical hydrocyclone chamber, m
ρ_c = Density of the continuous phase (water), kg/m³
μ_c = viscosity of the continuous phase (water), kg/m-s
Q = Volumetric flow rate at inlet of hydrocyclone, m³/h
Δρ = Density diff. between the continuous phase (water) (ρ_c) and the dispersed phase (oil) (ρ_oil), kg/m³
Note: The min. recommended density difference for a hydrocyclone is 50 kg/m³ @operating temperature

Hy₇₅ = c₁*(Re_D)^c₂
where:
Re_D = 4*Q*ρ_c / (π*D_cycl*μ_c)
Hy₇₅ = hydrocyclone number, dimensionless
Re_D = Hydrocyclone reynolds number, dimensionless
ρ_c = Density of the continuous phase (water), kg/m³
c₁ & c₂ = Empirically derived constants based on the hydrocyclone model

Some constants are tabulated below for some vendor models

This is all for today. Questions and comments from the members of "Cheresources" are welcome.

Regards,
Ankur.

The Easy And True Solution Of Colebrook-White Equations

Oct 14 2015 07:43 AM

There are about 6 different equations. Mode 2.51 is… 1/sqrt(f)=-2*Log(Rr/3.7+2.51/(Re*sqrt(f))) Mode 1.74 is… 1/sqrt(f)=1.74-2*Log(2*Rr+18.7/(Re*sqrt(f))) Mode 1.14 is… 1/sqrt(f)=1.14+2*Log(1/Rr)-2*Log(1+(9.3/(Re*Rr*sqrt(f))) Mode 9.35 is… 1/sqrt(f)=1.14-2*Log(Rr+9.35/(Re*sqrt(f))) Mode 3.71 is… 1/sqrt(f)=-2*Log(Rr/3.71+2.51/(Re*sqrt(f))) Mode 3.72 is… 1/sqrt(f)=-2*Log(Rr/3.72+2.51/(Re*sqrt(f)))
Since the equation starts with "1/sqrt(f)=" and have a another thing of the right like "sqrt(f)". But the equations have not been solved since 1930. May folks have made "approximations", and some are close and some are not right. But I have learned a easy and true solution for different equations.
My solutions are easy and true in Excel.
For the Colebrook-White equations change to f=1/(______)^2 where the ______ is the made right equations.

Rr= 0.02722 (Rr number is at cell B1)
Re= 66,391 (Re number is at cell B2)
Equation 1/sqrt(f)=-2*Log(Rr/3.7+2.51/(Re*sqrt(f))) (Cells A6 to A25 is 1 to 20)
Solution =1/(-2*LOG($B$1/3.7+2.51/($B$2*SQRT(B4))))^2 (This will be at cell B6)
Guess f= 1 (Guess number at cell B5)
1 0.0550474813204902 FALSE (Enter at C6 is "=B5=B6)
2 0.0554204850782122 FALSE (Copy cell B6 and C6 down to places)
3 0.0554188475042326 FALSE
4 0.0554188546575135 FALSE
5 0.0554188546262658 FALSE
6 0.0554188546264023 FALSE
7 0.0554188546264016 FALSE
8 0.0554188546264016 TRUE
9 0.0554188546264016 TRUE
10 0.0554188546264016 TRUE
11 0.0554188546264016 TRUE
12 0.0554188546264016 TRUE
13 0.0554188546264016 TRUE
14 0.0554188546264016 TRUE
15 0.0554188546264016 TRUE
16 0.0554188546264016 TRUE
17 0.0554188546264016 TRUE
18 0.0554188546264016 TRUE
19 0.0554188546264016 TRUE
20 0.0554188546264016 TRUE

Generalized Equation For Crude Oil Working Storage In Refinery Based On Various Factors

Oct 11 2015 08:08 AM

Dear All,

Refinery storage of raw materials (mainly crude oil) and finished products is a complex study and involves concepts of linear programming and Monte Carlo simulation. Refer the links below to know about these in context of raw material and product storage:

http://egon.cheme.cm...mannWassick.pdf

http://informs-sim.o...9papers/213.pdf

http://www.palisade...._simulation.asp

http://citeseerx.ist...p=rep1&type=pdf

However, crude oil storage in refinery can be put in the form of a simplified equation considering various factors such as: Maximum Cargo Capacity (crude parcel size), time duration, Crude Distillation Unit throughput and strategic stockpiling.

Today's blog entry provides such a simplified equation encompassing the above factors to get a preliminary estimate of crude oil storage in a refinery. The equation can be written as follows:

V_c = V_t + (D_e + D_d + D_u + D_s + D_l)*CDU_t + S

where:
V_c = Total Working Capacity of Crude of the Refinery, m³ (bbl)
V_t = Maximum Crude Oil Tanker Cargo or Parcel Size, m³ (bbl)
Note: For large refineries, VLCC tankers with volumetric capacities of 318,000 m³ (2,000,000 bbl) are often the preferred method of receiving crude oil due to the scale of economies.
D_e = Days of early arrival (normally a term that is considered zero in the above equation)
D_d = Days of Delayed Arrival (typically 3 days are considered)
D_u = Days for tanker unloading (typically 1 day)
D_s = Days for settling (typically 1 day)
D_l = Days for leaving, dewatering and crude oil analysis (typically 1 day)
CDU_t = CDU daily throughput i.e. plant capacity, m³/SD (BPSD)
S = Strategic Stockpiling Required (if any), m^₃ (bbl)

Crude oil tankers are planned to enter the port at regular intervals, but may be delayed for bad weather conditions or other reasons. Thus, if tankers are behind schedule, this period must be covered by the crude oil in stock. A maximum of three (3) days should be considered for this period. On the other hand, as the early arrival of a tanker can be controlled by adjusting the cruising speed, it may not be necessary to allow for early arrival in the normal situation.

Individual tank storage capacity and number of storage tanks should be decided on other considerations such as plot plan, pumping capacities to the CDU, limitations of fabrication of large sized storage tanks and HSE studies such as EIA and QRA. A practical maximum tank size could be 130,000 m³ (818,000 bbl) working capacity.

That is all for today's blog entry. Look forward to comments and observations from members of "Cheresources".

Regards,
Ankur.

Distance Between Mist Eliminator Top And Vapor Outlet Nozzle For Vertical Separators

Sep 04 2015 03:53 AM

Dear All,

Besides defining the Low-Low (LLL), Low (LL), Normal (NLL), High (HLL) and High-High (HHLL) liquid level based on criteria such as retention time, surge requirements for normal process control and adequate disengagement space during events such as large liquid slugs entering the separator or foaming, it is also important to define the vapor outlet nozzle distance from the top of the mist elimination device.

The objective of providing a minimum distance between the mist elimination device and the vapor outlet nozzle is to prevent channeling by promoting equal velocities across the entire surface area of the mist elimination device.

Refer the sketch below for two separate configurations of mist eliminator and vapor outlet nozzle for vertical gas-liquid separators:

The vertical distance X₄ is the minimum distance required between the mist eliminator top and the outlet nozzle and is given by:

X₄ ≥ (D - d₂) / 2 -------------(1)

Also

h ≥ d₂ ------------------(2)

where:
X₄ = vertical distance from mist eliminator top to vapor outlet nozzle as shown in sketch
D = Outside diameter of vessel
d₂ = Outside diameter of vapor outlet nozzle

Some standards recommend that X₄ should be a minimum of 12 inches even if the calculated value as per equation-1 is less than this value.

That is all for today folks and I would be happy to have comments and experiences from the "Cheresources" community members.

Regards,
Ankur.

Pressure Drop In Fixed (Single Phase Tubular Packed) Bed Reactors

Jul 29 2015 07:23 AM

Dear All,

Today's blog entry relates to pressure drop in fixed bed reactors.

Let us examine the components that contribute to the calculated pressure drop in fixed bed reactors. The design pressure drop should consider a safety margin on the calculated pressure drop.

Bed Pressure Drop: For both gases and liquids this should be calculated based on the "Ergun" equation given as:

(ΔP/L) = K*Re*(150 + 1.75*Re)*((1 – ε) / ε)^3*(µ^2 / (ρ*D_p^3))

where:
(ΔP/L) = pressure drop kPa/m (psi/ft) of bed
Re = Reynolds number, dimensionless = W*D_p/(µ*(1 - ε))
ε = Void fraction of bed, dimensionless

µ = viscosity of gas or liquid at conditions, Kg/m.s (lb/ft.hr)
K = Dimensional constant = 0.001 (Metric) = 1.665E-11 (USC)
ρ = gas or liquid density at conditions, kg/m³ (lb/ft³)
D_p= Equivalent particle diameter, m (ft)
W = mass flux of gas or liquid, kg/s.m² (lb/hr.ft²) based on reactor cross-sectional area

The equivalent particle diameter to be used in pressure drop calculations for cylindrical shapes is given by the following:

D_p = 3*D*L / (2*L + D)

where:
D_p = Equivalent particle diameter, m (ft)
D = Actual particle diameter, m (ft)
L = Average particle length, m (ft)

The "Ergun" constants of 150 and 1.75 have been given by fitting pressure drop data from a wide variety of particle systems. Use of the equation and these constants for a given unique shaped particle can sometimes result in significant error in the pressure drop prediction. In addition, error is often introduced into the pressure drop calculation through the estimate of bed voidage and the equivalent particle diameter. These errors are caused due to uncertainty in the particle density and particle dimensions.

Sock Loading: Prior to the 1970s, the standard method for loading catalyst in a fixed bed reactor was sock loading. In sock loading, a canvas tube conveys the catalyst from the reactor inlet manway to the bottom of the reactor catalyst bed. The sock is attached to a loading hopper or funnel at the reactor inlet, which discharges the catalyst through the sock upon the bed surface in a manner which prevents the individual particle (specifically cylinders) from finding a stable, horizontal rest position. The cylinders stack in various horizontal and vertical positions.

The positioning of catalyst cylinders in random orientations encourages bridging of cylinders and void spaces between cylinders. During reactor operations, these bridges and void spaces tend to collapse. Bed density then increases as the bed depth shrinks.

Dense Loading: Since 1970, refiners, catalyst manufacturers, and catalyst-loading contractors have developed dense-loading devices that dramatically reduce void spaces and bridging. Dense loading can increase catalyst bed densities by as much as 17%.

Moreover, unlike sock loading, dense loading does not require personnel inside the reactor to distribute the catalyst evenly from the sock. Workers inside the reactor require breathing air and weight distribution shoes to prevent crushing of the catalyst underneath their weight.

Dense loading is accomplished by introducing the catalyst particles (specifically cylinders) into the reactor in a manner that allows each cylinder to fall freely to the catalyst surface. Individual cylinders separately assume a horizontal rest position before being impinged by other cylinders. Under this regime, cylinders tend to pack horizontally, minimizing the possibility of bridging or creating void spaces.

Bed Lifting Pressure Drop: For the less frequently encountered upflow operation in a reactor, the calculated pressure drop from the above equation must be kept below the theoretical bed lifting pressure drop, preferably less than 50% and in no case more than 75%. The bed lifting theoretical pressure drop is given by:

(ΔP/L)_BL = K*(ρ_p – ρ)*(1 – ε)

where:
(ΔP/L)_BL = Theoretical Bed Lifting Pressure Drop of bed, kPa/m (psi/ft)
ρ_p = particle density of catalyst, kg/m³ (lb/ft³)
ρ = Density of gas or liquid at conditions, kg/m³ (lb/ft³)
ε = Void fraction of bed, dimensionless
K = Dimensional constant = 0.0098 (Metric) = 0.00694 (USC)

Inlet Nozzle Pressure Drop: Pressure drop through the inlet nozzle is the sum of the following terms represented in equation form:

ΔP_e = (K*ρ*(U_L – U_I)^2) / 2
ΔP_i = (1.3*K*ρ*U_I^2) / 2
ΔP_b = (0.5*K*ρ*U_L^2) / 2
where:
ΔP_e = pressure loss due to sudden expansion from line to expanded section of inlet distributor, kPa (psi)
ΔP_i = pressure drop due to impingement of the gas in the bottom plate or dish of the inlet distributor, kPa (psi)
ΔP_b = pressure drop through the slots of the inlet distributor, kPa (psi)
ρ = Density of gas or liquid at conditions, kg/m³ (lb/ft³)
U_I = velocity in expanded section of inlet distributor, m/s (ft/sec)
U_L = velocity in external piping, m/s (ft/sec)
K = Dimensional constant = 0.001 (Metric) = 2.156E-4 (USC)

Collector and Outlet Nozzle Pressure Drop: Pressure drop through the collector and outlet nozzle is the sum of the following terms represented in equation form:

ΔP_s = (2.8*K*ρ*U_S^2) / 2
ΔP_c = (0.5*K*ρ*U_L^2) / 2
where:
ΔP_s = Pressure drop through holes and slots of collectors, kPa (psi)
ΔP_c = Pressure drop due to sudden contraction at entrance to the outlet nozzle, kPa (psi)
U_S = velocity through holes and slots, m/s (ft/sec)
K = Dimensional constant = 0.001 (Metric) = 2.156E-4 (USC)

This is all for today's blog entry and I look forward to comments from the reader's of my blog.

Regards,
Ankur.

Zeolite Based Molecular Sieve Adsorbents In The Chemical Process Industry

Jun 19 2015 11:42 PM

Dear All,

Today's blog entry gives a brief overview of zeolite-based molecular sieves for physical adorption operations in the chemical process industry.

Since the 1960s, molecular sieve adsorbents have become firmly established as a means of performing difficult separations, including gases from gases, liquids from liquids and solutes from solutions. They are supplied as pellets, granules, or beads and occassionally as powders. The adsorbent may be used once and discarded or, more commonly may be regenerated and used for many cycles over an extended time period. They are generally stored in cylindrical vessels through which the stream to be treated is passed. For regeneration, two or more beds are usually employed with suitable valving, in order to obtain a continuous process. As a unit operation adsorption is unique in several respects. In some cases, one separation is equivalent to hundreds of mass transfer units. In others, the adsorbent allows the selective removal of one component from a mixture, based on molecular size differences, which would be extremely unlikely to be performed by any other means. In addition, contaminants can be removed from fluid streams to attain virtually undetectable impurity concentration. Adsorbents may be used in applications for adsorbing a few grams to several tons.

Before focusing on zeolite adsorbents, it is important to understand the two basic categories of adsorbents i.e. Amorphous and Crystalline.

Amorphous Adsorbents: The amorphous adsorbents (silica gel, activated alumina, and activated carbon) typically have specific areas in the 200-1000 m²/g range, but for some activated carbons much higher values have been achieved (~1500 m²/g). The difficulty is that these very high area carbons tend to lack physical strength and this limits their usefulness in many practical applications. The high area materials also contain a large proportion of very small pores, which renders them unsuitable for applications involving adsorption of large molecules. The distinction between gas carbons, used for adsorption of low molecular weight permanent gases, and liquid carbons, which are used for adsorption of larger molecules as color bodies from the liquid phase, is thus primarily a matter of pore size.

In a typical amorphous adsorbent the distribution of pore size may be very wide, spanning the range from a few nanometers (nm) to perhaps one micrometer. Since different phenomena dominate the adsorptive behavior in different pore size ranges, IUPAC has suggested the following classification:
micropores, <2 nm diameter
mesopores, 2-50 nm diameter
macropores, >50 nm diameter

The division is somewhat arbitrary since it is really the pore size relative to the size of the sorbate molecule rather than the absolute pore size that governs the behavior. Nevertheless, the general concept is useful. In micropores (pores which are only slightly larger than the sorbate molecule) the molecule never escapes form the force field of the pore wall, even when in the center of the pore. Such pores generally make a dominant contribution to the adsorptive capacity for molecules small enough to penetrate. Transport within these pores can be severely limited by steric effects, leading to molecular sieve behavior.

The mesopores make some contribution to the adsorptive capacity, but their main role is as conduits to provide access to the smaller micropores. The macropores make very little contribution to the adsorptive capacity, but they commonly provide a major contribution to the kinetics. Their role is thus analogous to that of a super highway, allowing the adsorbate molecules to diffuse far into a particle with a minimum of diffusional resistance.

Crystalline Adsorbents: Crystalline adsorbents are the zeolites and zeolite analogues such as silicalite and the microporous aluminum phosphates. where the dimensions of the micropores are determined by the crystal framework and there is therefore virtually no distribution of pore size. However, a degree of control can sometimes be exerted by ion exchange, since, in some zeolites, the exchangeable cations occupy sites within the structure which partially obstruct the pores. The crystals of these materials are quite small (1-5 microns) and they are aggregated by a suitable binder (generally a clay) and formed into macroporous particles having dimensions large enough to pack directly into an adsorber vessel. Such materials therefore have a well-defined bimodal pore size distribution with the intracrystalline micropores (a few tenths of a nanometer) linked together through a network of macropores having a diameter of the same order as the crystal size (~1 micron).

Here it is important to introduce "Desiccants" as a class of adsorbents and the following describes them.

Desiccants: A solid desiccant is simply an adsorbent which has a high affinity and capacity for adsorption of moisture so that it can be used for selective adsorption of moisture from a gas (or liquid) stream. The main requirements for an efficient desiccant are therefore a highly polar surface and a high specific area (small pores). The most widely used desiccants are silica gel, activated alumina and the aluminum-rich zeolites (4A or 13X).

The zeolites have high affinity and high capacity at low partial pressures. This makes them useful desiccants where a very low humidity or dew point is required. The micropores of 3A zeolite are small enough to exclude most molecules other than water. It is therefore useful for drying reactive gases. The major disadvantage of zeolite desiccants is that a high temperature is required for regeneration (>300 deg C), which makes their use uneconomic when only a moderately low dew point is required.

Temperature Swing Adsorption (TSA) Process: A temperature-swing or thermal-swing adsorption (TSA) cycle is one in which desorption takes place at a much higher temperature than adsorption. The principal application is for separation in which contaminants are present at low concentration, i.e for purification. The TSA cycles are characterized by low residual loadings and high operating loadings. These high adsorption capacities for low concentrations means that cycle times are long, hours to days to months, for reasonably sized beds. This long cycle time is fortunate, because packed beds of adsorbent respond slowly to changes in gas temperature. A purge and / or vacuum removes the thermally desorbed components from the bed, and cooling returns the bed to adsorption condition. Systems in which species are strongly adsorbed are especially suited to TSA. Such applications include "Drying", "Sweetening", "CO2 removal", and "pollution control".

A detailed description of the TSA process would require another blog entry and I end it with the description provided above.

Applications for Adsorbents:

Drying: The single most common gas phase application for TSA is drying. The natural gas, chemical, and cryogenic industries all use zeolites, silica gel, and activated alumina to dry streams. Adsorbents are even found in mufflers.

Zeolites, activated alumina, and silica gel have all been used for drying of pipeline natural gas. Alumina and silica gel have the advantage of having higher equilibrium capacity and of being more easliy regenerated using waste level heat. However, the much lower dew point and longer life attainable with 4A makes zeolites the predominant adsorbent. Special acid-resistant zeolites are used for natural gas containing large amounts of acid gases, such as H₂S and CO₂.

The low dewpoint that can be achieved with zeolites is especially important when drying feed streams to cryogenic processes to prevent freeze-up at process temperatures. Natural gas is dried before liquefaction to liquefied natural gas (LNG), both in peak demand and in base load facilities. Zeolites have largely replaced silica gel and activated alumina in drying natural gas for ethane recovery utilizing the cryogenic expander process, and for helium recovery. The air to be cryogenically distilled into N₂, O₂ and argon must be purified of both water and CO₂. This purification is accomplished with 13X zeolites.

The 4A zeolite, silica gel, and activated alumina all find applications in drying synthesis gas, inert gas, hydrocracker gas, rare gases, reformer recycle H₂. Cracked gas before low-temperature distillation for olefin production is a reactive stream. The 3A or pore-closed 4A zeolite selectively adsorbs water but excludes the hydrocarbons, thus preventing coking. It also prevents co-adsorption of hydrocarbons which would otherwise be lost during desorption with the water. Small pore zeolites are also applied to the drying of ethylene, propylene, and acetylene as they are drawn from storage. When industrial gases containing Cl₂, SO₂ and HCl are dried, acid-resistant zeolites are used.

A relatively new application for zeolites is the prevention of corrosion in automotive mufflers.

Sweetening: Another significant purification application area for adsorption is sweetening. H₂S, mercaptans, organic sulfides and disulfides, and COS need to be removed to prevent corrosion and catalyst poisoning. They are found in H₂, natural gas, de-ethanizer overhead, and bio-gas. Often adsorption is attractive because it dries the stream as it sweetens.

In the sweetening of wellhead natural gas to prevent pipeline corrosion, 4A zeolites allow sulfur compounds removal without CO₂ removal (to reduce shrinkage), or the removal of both to upgrade low thermal content gas. When minimizing the formation of COS during desulfurization is desirable, calcium-exchanged zeolites are commonly used because they are less catalytically active for the reaction of CO₂ with H₂S to form COS and water. Natural gas for steam-methane reforming in ammonia production must be sweetened to protect the sulfur-sensitive, low temperature shift catalyst. Zeolites are better than activated carbon because mercaptans, COS, and organic sulfides are also removed. Many refinery H₂ streams require H₂S and water removal by 4A and 5A zeolites to prevent poisoning of catalysts such as those in catalytic reformers.

Other Separations: Other TSA applications range from CO₂ removal to hydrocarbon separations, and include removal of air pollutants and odors, and purification of streams containing HCl and boron compounds. Because of their high selectivity for CO₂ and their ability to dry concurrently, 4A, 5A, and 13X zeolites are the predominant adsorbents for CO₂ removal by temperature-swing process. The air fed to an air separation plant must be H₂O and CO₂ free to prevent fouling of heat exchangers at cryogenic temperatures; 13X is typically used here. Another application for 4A-type zeolite is for CO₂ removal from base load and peak-shaving natural gas liquefaction facilities.

Zeolites with high acid resistance, such as mordenite and clinoptilolite, have proven to be effective adsorbents for dry SO₂ removal from sulfuric acid tail gas, and special zeolite adsorbents have been incorporated into the UOP PURASIV S process for this application.

Zeolites have also proven applicable for removal of nitrogen oxides (NO_x) from wet nitric acid plant tail gas by the UOP PURASIV N process.

Mordenite and Clinoptilolite zeolites are used to remove HCl from Cl₂, chlorinated hydrocarbons, and reformer gas streams.

Refer the link below for details on application of zeolite molecular sieves in various areas of the chemical process industry:

Which_Zeolite_To_Use

Additionally refer the attached table to get an overview of the commonly used zeolite molecular sieves in the chemical process industry:

While making an attempt to make this blog entry as short as possible, I feel the information provided is a bare minimum to get an overview of how zeolite based molecular sieves are useful in adsorption processes. I look forward to comments from the esteemed members of the "Cheresources" community on this blog entry.

Regards,
Ankur.

Skid Mounted Modular Mini Crude Refining Units

May 28 2015 01:05 AM

Dear All,

In remote crude oil drilling locations or where some value addition on the crude is required such as production of low cetane diesel (generally less than 40) and straight run naphtha with low first investment costs, skid mounted modular mini refining crude units are the answer.

Let us examine the advantages of a skid mounted modular unit:

1. Lower construction and installation costs

2. Ideal choice for remote locations

3. Less manpower requirement for installation, operation and troubleshooting of the unit

4. Very short installation, commissioning and operation times. A skid mounted modular crude distillation unit with a capacity of 300 to 12,000 BPD could be made operational within weeks from it's arrival at the designated location.

5. Since the units are skid mounted they are easily transportable and can be moved from one location to another in a short duration of time. This feature allows the units to be procured on short or long term lease basis thereby further reducing cost for the operator and increasing profitability by moving the unit to the production source as and when desired.

6. Higher quality workmanship can be achieved in view of the fact that these units are assembled in sophisticated workshops utilizing high quality machinery and considering that these may have to face the rigours of frequent transportation depending on the operator's philosophy of operation.

7. Construction as modules allows transport by sea in standard ocean containers.

I am providing a list of some established names who design, build, install and commission such units. Links are provided for some of the leading suppliers of the skid mounted modular crude mini crude refining units for the benefit of the readers.

http://www.skmind.co...y_Brochure_.pdf

http://mgiprocess.co...-refineries.htm

http://chemexmodular...ular_Refineries

http://www.petrostar...ery-Summary.pdf

As a cautionary advice the credentials of the suppliers of these units needs to be verified as a whole in terms of engineering, workshop fabrication of skid mounted modules, skilled pre-commissioning and commissioning personnel and after-sales service. It would be unwise for a prospective client to try to procure such units from a source where there are multiple agencies involved for engineering, fabrication and pre-commissioning / commissioning, due to the possibility of encountering fly-by-night operators who are out to make a fast buck at the client's peril. The most prudent way for a prospective client would be to check out the performance track record of the supplier in terms of quantity and quality of units supplied in the past and proper testimonials from satisfied clients.

Comments from the readers of my blog are welcome.

Regards,
Ankur.

Fireproofing Standards - The Need And Reasons For Their Existence

May 19 2015 07:09 AM

Just like most other business, the fireproofing business has a code of conduct and some established standards which are mandatory for all the fireproofing companies to follow while conducting their work. These standards are formed, maintained and updated by NFPA, a regulatory body in USA and can be found online on their website.

Most professional companies will make sure their work adheres to certain quality benchmarks, because that is expected out of them; but a central body establishing standards for the work to be performed does have a lot of benefits attached to it. There are a handful of reasons why such fireproofing standards exist, take a look:

Similar Safety levels
In the absence of standards, it will be a chaotic situation in terms of maintaining similarity in the level of safety measures to be undertaken for commercial or residential buildings. The standards provide uniformity and an organized way of establishing and executing procedures which need to be undertaken by fireproofing contractors. NFPA works as a central repository and provides valuable information about the minimum safety standards expected in carrying out fireproofing work. These standards are set for a broad range of objectives, the primary among them maintaining homogeneous safety standards across the country for various fireproofing work done by any contractor.

Minimizing Insurance Related Disputes

(Image Credit: http://gotinjured.co...e-disputes.jpg)

The companies affected by fire would definitely lodge a claim with the insurance companies regarding the loss sustained by business due to fire. The insurance companies would follow a certain procedure before the approval of such claims and this would normally involve verifying the materials being used, the fireproofing safety norms being followed and whether the compliance with the standards was met by the fireproofing contractors and much more.

The bigger the amount of the claim, the more detailed is the process of verification of insurance companies. Even fireproofing contract companies would prefer insurance to shift the burden of indemnity, in case they are sued by the company which hired them for fireproofing. The best case scenario in these circumstances for contractors would be compliance with the standards.

These standards would work as a shield for them against any financial loss in case of loss due to fire at any of the premises of their clients. If they have complied with all the set standards and followed the requisite procedures, they cannot be held accountable for the loss. Thus standards help in minimizing insurance related disputes. Most industrial fireproofing contractors in Alaska; which is a state prone to regular wildfires, would consider it a wise option to have insurance for them.

Ease of Implementation

Since the standards are set by a Government body and are mandatory to follow, there are less chances of any confusion or ambiguity in terms of industrial design. The contractors, the engineers, architects and everyone involved with the construction of a structure are well aware of legal requirements to comply with and as such there are no procedural delays in terms of construction from any of the parties involved. The standards guarantee frictionless functioning of different individuals who collaborate on a given task of constructing a fire resistant building and are involved in the fireproofing process. This speeds the whole process and makes it really simple for everyone involved.

Help in Costing the Work

Since the standards are very detailed in specifying the minimum thickness of the fireproofing material and what exact materials to be used, the costing of these contracts becomes really easy and transparent. The companies can differentiate on the basis of their support, experience and more factors but not on the basis of the products used. The material requirements and characteristics are so detailed that it becomes a very open market where the service providers and buyers have the same information available at their disposal. This greatly reduces any wastage of time in negotiations involved in relation to costing a fireproofing job.

Planning Maintenance and Repairs

(Image Credit:http://www.tracyandm...aintenance.png)

Since the standards elaborate so much in terms of materials, their composition, thickness and other parameters, it becomes really easy to plan for the maintenance and repairs of the building structure. The minimum acceptable levels set forth in the standards should always be maintained and as such if contractors feel they need to update, repair and/or do any maintenance work due to the wear and tear or any other factor which would result in depreciation of the equipment or the fireproofing materials, it can be done easily.

Organized System of Updating Standards

Since there is a central body which is responsible for issuing fireproofing standards, it makes the job of the players in the industry much easier because they have a reputed source to look after them in terms of maintaining, updating and revising these standards from time to time as and when the need arises according to the market conditions and new developments.

The fireproofing contractors just look at the NFPA website and have instant access to updated standards and thus never get into hot water for not complying with certain conditions. The work becomes easier for contractor companies because industry changes, evolution of methods and development of new methods are all taken into account while formulating new standards or editing the existing ones by NFPA.

Thus, fireproofing standards make life easier for everyone in the industry. From contractors, clients, engineers, fire equipment manufacturer and fireproofing service providers to insurance companies. The guidelines are needed to avoid chaos, and mostly minimize loss of property or human lives in the case of fires. Fireproofing standards justify their existence and are extremely useful for all the stakeholders.

Overall Heat Transfer Coefficient For Tank Heaters (Steam) Heating Hfo / Asphalt

Apr 29 2015 01:41 PM

Dear All,

Today's blog entry provides an equation for Overall Heat Transfer Coefficient for storage tanks handling Heavy Fuel Oil (HFO) / Asphalt and provided with tank heating coils using steam as a heating medium.

If the heat loss rate Q (W or Btu/hr), from the tank is known, then the steam coil surface area can be calculated and thus the coil geometry fixed. The general equation for sizing heat exchange equipment can be utilized for this:

Q = U_o*A*ΔT

or

A = Q /( U_o*ΔT)

where:
A = Steam Coil surface area, m² or ft²
Q = Heat Loss Rate from tank, W or Btu/hr
U_o = Overall Heat Transfer Coefficient, W / m².⁰C, Btu / hr.ft².⁰F
ΔT = Temperature difference between steam supply temperature and bulk process fluid temperature in tank, ⁰C, ⁰F

For heat loss rate from storage tanks, refer this very well known post on "Cheresources":

http://www.cheresour...icle/?hl=kumana

Now for the equation for the equation for the Overall Heat Transfer Equation, U_o

United States Customary Units:

U_o = 30*(T_c - T_f)^0.14 / (µ_f)^0.4

Metric Units:

U_o = 11.7*(T_c - T_f)^0.14 / (µ_f)^0.4

where:

T_c = Temperature of the steam, ⁰F, ⁰C
T_f = Bulk Temperature of the process fluid, ⁰F, ⁰C
µ_f = The absolute viscosity of the process fluid at the average film temperature ((T_f + T_i) / 2), cP, Pa.s

where:
T_i = Temperature of the coil surface in contact with the fluid, ⁰F, ⁰C

Generally T_i is 10-15⁰C more than the bulk process fluid temperature

Once the steam coil surface area A is calculated, the length of the coil can be calculated after fixing a NPS or OD of the steam coil pipe.

That is it for today's blog entry. I look forward to comments from the members of "Cheresources" on this blog entry.

Regards,
Ankur.

Safety Integrity Level (Sil) Definition And Brief Explanation

Mar 29 2015 03:00 AM

Dear All,

Most young process engineers have heard the term SIL but not got involved in what SIL is all about. In fact, there is a misconception among many younger process engineers that SIL is solely related to the advanced "Control & Automation" part of a process plant and process engineers need not get involved in a detailed SIL study or SIL review except for providing process data for the instrumentation under SIL study.

This is far from the truth. Process engineers need to be an integral part of any SIL review or SIL study because the basis or starting point of any SIL study is proper evaluation and finalization of the "Basic Process Control System" (BPCS) based on process studies / reviews such as "Design Review" and "Hazard & Operability Studies" (HAZOP).

SIL studies and SIL allocation for any process plant is a logical step ahead of the BPCS for safe and reliable plant operation.

Now, that I have explained how it is important for process engineers to be part of a SIL study exercise, let us get to the definitions of various terms and explanation of the methodology of SIL.

Some basic terms:

1. Probability of Failure on Demand (PFD): It It is a measure of safety system performance in terms of the Probability of Failure on Demand (PFD). It is expressed as a negative exponential of 10, for example, 10^-5 .

2. Risk Reduction Factor: This is the inverse of of the POF and provides the reduction in risk by implementation of a SIL level to any critical safety-related instrumentation.

3. Safety-Instrumented Systems: It is a process plant instrument system which is designed to prevent or mitigate hazardous events by taking a process to a safe state when predetermined conditions are violated. Other common terms for SIS are safety interlock systems, emergency shutdown systems (ESD), and safety shutdown systems (SSD).

SIL evaluation is done for Safety-Instrumented Systems (SIS). Each SIS has one or more Safety Instrumented Functions (SIF). To perform its function, a SIF loop has a combination of logic solver(s), sensor(s), and final element(s). Every SIF within a SIS will have a SIL level. These SIL levels may be the same, or may differ, depending on the process. It is a common misconception that an entire system must have the same SIL level for each safety function.

SIL Levels (as per IEC 61508):

There are four discrete integrity levels associated with SIL: SIL 1, SIL 2, SIL 3, and SIL 4. The higher the SIL level, the higher the associated safety level, and the lower probability that a system will fail to perform properly. As the SIL level increases, typically the installation and maintenance costs and complexity of the system also increase. Specifically for the process industries, SIL 4 systems are so complex and costly that they are not economically beneficial to implement. Additionally, if a process includes so much risk that a SIL 4 system is required to bring it to a safe state, then there is a fundamental problem in the process design that needs to be addressed by a process change or other non-instrumented method.

The identification of risk tolerance is subjective and site-specific. The owner / operator must determine the acceptable level of risk to personnel and capital assets based on company philosophy, insurance requirements, budgets, and a variety of other factors. A risk level that one owner determines is tolerable may be unacceptable to another owner. Many well-known operating companies have their in-house guidelines / standards for assigning SIL levels for specific SIS and for a given type of process plant / unit.

As part of the engineering design cycle, SIL or SIS studies are conducted in a manner similar to other studies such as Design Review & HAZOP. The SIL or SIS study basic prerequisite is, availability of P&IDs and Plant Operation / Control / Safeguarding philosophy, which have been updated to incorporate all process design and HAZOP review comments.The SIL or SIS study is jointly driven by the process engineering and Control & Automation (Instrumentation) engineering group. A HSE engineer also plays an important part in this study / review. Based on the recommendations and report of the SIS study, SIL levels are assigned to various SIS systems in the process plant and instrument system architecture for these SIS systems defined.

The finer details of how the system architecture for the SIS needs to be constructed is handled by the Instrumentation Engineer and is beyond the scope of this blog article.

A basic explanation on SIL is also provided on the links provided below:

http://en.wikipedia....Integrity_Level

http://www.enggcyclo...ity-levels-sil/

A google search will provide many more articles related to SIS/SIL.

Hope this blog article helps process engineers to understand the basics of SIL and SIS. Looking forward to comments from the reader's of my blog.

Regards,
Ankur.

Nit Warangal, Department Of Chemical Engineering Golden Jubilee Celebrations

Mar 15 2015 10:15 AM

Dear All,

It is heartening to note that the contribution of "Cheresources" to the global chemical engineering community is being recognized all over including academic institutions.

National Institute of Technology (NIT), Warangal, is one of the premier engineering institutes of India providing bachelors, masters and doctoral degrees in the field of engineeering, technology and management.

NIT Warangal is a federally funded institute by the Government of India and ranks among the top fifteen technological institutes of India. For more details on NIT Warangal, refer the following link:

http://en.wikipedia....ology,_Warangal

It recently (March 13-14) concluded a national level student's conference named "ChemFlair" conducted by its Department of Chemical Engineering on the occasion of completing 50 years from its inception.

It was a singular honor for me, to be invited as a Chief Guest on this occasion as a practicing chemical engineer. The chemical engineering department of NIT-W has a very distinguished faculty with most of them holding Doctoral degrees from premier engineeeing institutes of India such as IITs and from top notch universities in the United States.

Since it was a undergraduate student's conference, chemical engineering undergraduate student's were invited from all over the country to participate in discussions, give presentations, participate in Q&A sessions and various technical quizzes.

I made a presentation titled "Phases of Process Design Engineering" from the perspective of an engineering consultant and contractor. The idea was to give the undergrad's a bird's eye view on the practical aspects of engineering when working in a business environment of engineering, procurement and construction of chemical process plants.

The interaction with the faculty and the student's made me realize that at the undergraduate level student's are quite unaware of practical business scenarios involving engineering of a chemical process plant and my presentation helped them in clearing quite a few gaps in their understanding. One another aspect that I could make them understand about engineering design was implementing a safe and environment friendly process design. While most of them were aware of Process Flow Diagrams, Process Modeling and Simulation, Heat and Mass Balance, P&IDs, Process Datasheets, Equipment Sizing, almost none of them had awareness of safety studies conducted during the engineering design phase, such as HAZID, HAZOP, SIL etc. For many of them, my explanation on the safety aspect of engineering design was a revelation.

During the inaugural address and while being introduced to the particpant's of the conference, I was understandably delighted to see the "Community Index" page of "Cheresources" and "Ankur's Blog" being displayed on the screen. It was good to see that "Cheresources" contribution to our community was being acknowledged by the academia.

While many of the younger generation of internet savvy student's were aware of "Cheresources", they had only gone through the forums on a very superficial basis. After my interaction with them, many of them expressed their desire to increase their involvement with "Cheresources".

To conclude, it was a great honor to be part of the student's conference organized by one of the premier engineering institutes of India and more so to interact with the younger generation of engineers and would-be engineers who will guide the future of chemical engineering in the years to come.

Would love to hear comments from the readers of my blog.

Regards,
Ankur.

Requirement Of Adequate Ventilation In Process Areas

Feb 18 2015 12:20 PM

Dear All,

Process Engineers normally are not directly involved in Heating, Ventilation, Airconditioning (HVAC) requirements of a Chemical Process Plant. HVAC engineering is a specialized branch of engineering and HVAC engineers normally involve themselves in system design for a chemical process plant. However, adequate ventilation is a matter of concern for all engineers who consider safety as an integral part of any chemical process plant and it is important to know the hazards related to inadequate ventilation.

NFPA 30 defines adequate ventilation from the perspective of a chemical process plant as follows:

An area is adequately ventilated if it is ventilated at a rate sufficient to maintain the concentration of vapors within the area at or below 25% of the lower flammable limit.

This shall be confirmed by one of the following:
- Calculations based on the anticipated fugitive emissions; or
- Actual vapor concentration sampling under normal operating conditions, conducted at a radius of 5 feet from equipment.

An acceptable alternative is to provide ventilation at a rate of not less than 1 cubic foot per minute per square foot of solid floor area.

Ventilation shall be accomplished by natural or mechanical ventilation, with discharge of exhaust to a safe location, without recirculation of the exhaust air.

Completely open (from all 4 sides) outdoor locations are usually considered adequately ventilated.

Process equipment buildings are buildings that contain hydrocarbon piping and equipment. Some examples are: analyzer buildings, metering stations, pump stations, compressor stations, and separation stations. They should have openings on all sides whenever practical to allow for ventilation. If they must be fully enclosed due to ambient conditions, adequate ventilation needs to be provided. to prevent the accumulation of flammable gases. The building exhaust vents should be located to preclude the accumulation of gases at low points such as pipe trenches, as well as at the ceiling.

Process buildings are frequently ventilated with windows, floor louvers, and roof ventilators.

A minimum of six air changes per hour are recommended for process buildings.

If mechanical equipment provides the required ventilation, safeguards are needed to protect against its undetected failure.

Discharge or exhaust must be to a safe location outside the building.

Ventilation rates can be achieved either by continuous introduction of fresh makeup air into the enclosure, or by recirculation of air in the building. A recirculation system should ensure that the air is monitored continuously using a system that automatically alarms, stops recirculation, and provides full exhaust to the outside in the event that vapor-air mixtures over 25% of the lower flammable limit are detected.

Recirculation should be designed with adequate air movement and direction to minimize “dead” areas where flammable vapors such as heavy hydrocarbons may collect.

If conditions include the risk of a large flammable vapor release occurring in a confined space, and the calculated rate of diluent ventilation is not sufficient to dilute and disperse the released vapor to below the "Lower Flammable Limit" (LFL) within a reasonable time (i.e., four hours), then supplemental emergency ventilation should be provided. Emergency ventilation can be natural ventilation through panels or louvers, or switching recirculation fans to full fresh air make-up or exhaust. The travel direction of ventilated vapor should avoid its reaching an ignition source outside the enclosed space being ventilated.

It is recommended that when combustible gas detectors are installed they provide an alarm at 20% of LFL and are interlocked to rotary process equipments such as pumps and compressors so that they cannot be started or they shut down when the detector detects a value of 60% of LFL.

To conclude, adequate ventilation in a chemical process plant is of utmost importance and process engineers should be aware of good ventilation practices for a safe design.

Hope to have comments from the members of "Cheresources".

Regards,
Ankur.

Depressuring In The Dense Phase

Feb 04 2015 10:07 AM

How to depressure in the supercritical phase using dynamic depressuring utility in Hysys?

Process systems containing large inventories of gas and light hydrocarbon liquids at high pressure have the potential to create a major hazard during a plant upset. To minimize the potential for the creation of a major hazard, blow down valves shall be used for depressuring all equipment containing large inventories of high pressure gas / liquid in the event of a fire, a serious operating excursion, or a utility failure.

The depressuring system shall reduce the pressure of the equipment within a fire zone to 7barg or 50% of the design pressure, whichever is lower, within 15 minutes for high-rate depressuring or within 60+ minutes for low-rate depressuring. Blow down valves sized for the above cases will also be sized for maintenance and normal shutdowns.
Depressuring can be done as follows;

Fire (Hot) Depressuring API 521 (Immediate depressurization of system fires) – Used as the governing case when sizing blowdown valves
Adiabatic Depressuring/Isochoric (Cold) Depressuring (depressuring during utility failure or equipment shutdown, not due to fire)

Depressuring parameters

Vessel Dimensions: vessel dimensions must be entered such that you represent volume occupied by each phase (I usually enter the minimum wetted area expected), metal weight of model or thickness. For compressor depressuring enter the total volume between each stage between each ESD.
Valve Specifications: Any valve type can be used usually for the fire case it is best to determine use the calculate CV option and then use the same parameters when doing isochoric depressuring to determine vessel MDMT. For depressuring fluids in the dense phase it is best to use the general valve sizing equation and “calculate pressure” adjusting the valve size to meet the required 7barg
Heat Loss Model: I usually select the detailed method to provide more accurate results however “none” is often used for fire case to be more conservative:

o Metal thickness

o Insulation thickness

o Ambient Temperature

1)Hot Depressuring

This case is usually used to predict the size of the blow down relief valve
Initial pressure – should be your PSV set pressure or highest possible operating pressure
Initial temperature – highest operating temperature
Final Pressure – 7barg or 50% of your PSV set pressure whichever is lower
Time – 15 minutes
Liquid level – higher level is more conservative
Heat input model – API 521

2)Cold Depressuring

This case is usually used to predict attain the minimum vessel design temperature, associated piping design temperature and material (carbon steel, stainless steel, etc)
Initial pressure – for adiabatic start with the settle out pressure of the compressor attained from the settle out calculation or for isochoric start with the design pressure to be conservative although normal operating pressure can also be used
Initial temperature – use the minimum ambient temperature as a conservative assumption for the isochoric approach or the compressor settle out temperature for adiabatic
Final pressure should be 0.5 bar or atmospheric
Liquid level – lower provides lower MDMT

Depressuring from the dense phase
Depressuring from the supercritical point Hysys is not able to find a solution most of the time this is due to the instability of Hysys to predict fluid properties. What you will probably notice is that the vapour phase fraction will go from 0 to 1 while the depressuring utility is running.
To help solve the problem one can adjust what is known as the dense phase tuning (DPT) factor between 0.5
In addition to this it is best to separate out components such as water, TEG, other than light hydrocarbons that are likely to be vapour at atmospheric pressure etc. and the initial temperature using a component splitter and use the result stream to depressure the system.
My trick to selecting the best DPT is trial and error, I would incrementally increase the DPT while trying to attain the highest vapour molecular weight. To do this you must use a two phase separator that you use to split vapour and liquid at the final condition (atm pressure). Adjust it until the vapour molecular weight becomes constant with any change in the tuning factor.

Note: I found Hysys does not give accurate results when adjusting the time step to a very low value like 0.01sec its best to use a higher time step for more accurate results.

If you would like more detailed information the aspentech website offers great information on Dynamic depressuring.

Online Store And Chexpress Run Coming To An End

Jan 24 2015 03:34 PM

For many years, Christa Semko has been providing us with chemical manufacturing news updates through her blog. For even more years, we've had an online store where you can purchase quality engineering calculations in MS Excel format. We'll be ending both of these features in 2015.

The online software store will close on June 30, 2015. So, please, if you want to purchase any of the titles available in the store, please do so as soon as possible.

ChExpress has been discontinued as of January 1, 2015.

OK...so maybe that's some sad news. I really enjoyed Christa's updates, but clearly there are many other sources of the same information available. We could have continued ChExpress, but really there are folks out there who do it better and faster than we could.

The online store has seen sales decline for the past 2 or 3 years. This was surprising to me...a little. I don't know exactly the reason for the decline, but they could include:

1. Folks moving to mobile applications and devices where macro-enabled spreadsheets either don't work or don't work well.

2. A general concern about the future of MS Excel which may be making people hesitant to invest money in a calculation stuck in that particular format.

3. A general need for these calculations to be cloud-based and accessible from any where.

What ever the reason may be, it's clear that our online store make little sense any longer.

Let me be clear about this though....just because these two (2) services are being discontinued does not mean that Cheresources.com is going away.

Rather, we're going to continue to be the best place for chemical engineers to come and discuss their technical issues among one another. That's what we're best at and that's what we're going to continue to do for our community members.

At this time, no other services are being considered for discontinuation.

Don't Be An Engineer At The Expense Of Common Sense

Jan 04 2015 05:24 AM

Dear All,

Happy New Year to all of you and I start off with a blog entry which you may find quite interesting.

Being an engineer is justifiably a matter of pride since engineers have made an immeasurable contribution to the betterment of the world we live in.

However, as Homo sapiens, who are the considered on the top of the chain of living beings we must understand that our basic intelligence is the attribute that distinguishes us from other species of the animal kingdom and gives us the hallowed status we have. We have evolved from the stone-age to today's world of gadgetry and gizmos because we have used our intelligence or in other words our common sense more than any other species of the animal kingdom.

While the meaning of common sense can be debated from various perspectives of the human society, I am only going to specifically dwell on common sense from the perspective of a design engineer. Wikipedia has a long article on the various aspects of common sense, which can be read at the link below:

http://en.wikipedia....ki/Common_sense

Coming to specifics, I would like to discuss how common sense and the ability to question and challenge should be used by a design engineer:

1. Certain documents like design basis are prepared at the start of the project. Subsequent engineering design work results from the status quo of the design basis. In other words, the design basis needs to be frozen at the earliest and should not remain dynamic throughout the project unless there are some compelling circumstances. Often, design basis provides listing of future engineering documents that will be prepared during the course of the project. Many of these future documents are identified by an alpha-numeric code and description which is established at the start of the project. A number of such documents identified in the design basis by this code and description are dynamic in nature till the end of the project. An example would be P&IDs for the project. While listing the documents by the alpha-numeric code and the description makes perfect sense in the design basis, providing the revision status of these dynamic document does not. There is absolutely no prudence in revising the design basis because the revision status of the dynamic documents has changed. Engineers must realize that when a listing of a dynamic document is made in a frozen or status quo document, they have the responsibility to refer the latest revision of that document. This is what I mean by common sense.

2. While I do not condone gramatically incorrect or misspelt language, it is important to note that documents such as design and sizing calculations with formulas, equations, sketches do not diminish in stature just because of a few misspelt words or grammatically incorrect language. Anybody rejecting the document solely on these grounds, does need to have lessons in common sense. Obviously, if time is not of essence, which normally is, you can decorate the document with Queen's English and make it as glossy and slick as an advertisement billboard.

3. In a majority of projects either the client or his PMC (Project Management Consultant) checks the engineering deliverables provided by the engineering contractor. Often it is seen that the client or his PMC will put multiple question marks on a particular section of the document, or ask vague and unrelated open-ended questions. I consider this behavior as trying to insult or humiliate the engineering contractor and would treat it with the contempt it deserves. Obviously, people indulging in this kind of antics need extended lessons in etiquette and common sense. It also puts a big question mark in terms of their capabilities as an engineer.

4. E-mail communication betweeen various parties during the project has to be very carefully scrutinized before being sent. Being a client does not give license for using uncouth, foul and patronizing language to the service provider in written communication. As a client, I have had my fair share of grievances with the service provider and many a times I have given them a piece of my mind, however, only on telephone and never by written communication. Remember, the written word has far more grave consequences, specifically when it is bad, than the spoken word. This is one more thing which relates to common sense.

5. Engineering contractors earn revenue and profit based on time management of their skilled personnel. This time management is in terms of their budgeted manhours for the project. From a strictly technical view point, any over-run over the budgeted manhours means a loss of revenue and profits for the engineering contractor. Most clients have little or no concern about the time management of the engineering contractor. They have an expanding wish-list over the tenure of project where they want the engineering contractor to explore all kinds of possibilities and permutations-combinations for the project. If the client is willing to pay for such kind of research and development work, then there is no argument. However, in a majority of cases clients are unwilling to do so and the contractor is burdened with work which is far beyond the scope of work envisaged at the start of the project. While this is undoubtedly unethical on the part of the client, it is also the responsibility of the senior management on the engineering contractor's side to ensure that the client pays for the extra work demanded by him. Businesses do not survive on freebies and charities. This is again common sense for both the client and the service provider.

Well it is time to conclude this somewhat descriptive blog. However, this is not the end of it. I may come out with a Part 2 on the same topic with more common sense related points. Meanwhile, I request the readers of my blog to come out with points related to common sense from an engineering perspective, which they feel can make the world a lot better place for engineers to work.

Regards,
Ankur.

PS: My spouse and a majority of women think that most men have ridiculously low levels of common sense related to home affairs and in managing children. I have no logic to disagree. Do you have a logic to counter this charge? If yes, please share.

Chexpress - December 17, 2014

Dec 17 2014 06:15 PM

North America

Sales

Dow Chemical is selling two businesses for a total of $225 million. Vertellus Specialty Materials will buy Dow’s sodium borohydride business and Valfilm North America will buy a Dow polyolefin films plant in Findlay, Ohio. Dow expects both sales to close during the first quarter of 2015. The divestiture of the sodium borohydride business includes a manufacturing facility in Elma, Washington. The polyolefin plant in Ohio will close in January, but Valfilm will restart it in February.

Expansion

Chevron Phillips Chemical Company LP has completed an ethylene expansion at its Sweeny complex in Old Ocean, Texas. With the addition of a tenth furnace to ethylene unit 33 at the complex, the expansion is expected to increase annual production by 200 million pounds. Expansion construction began in 2013. The Sweeny complex is now capable of producing roughly 12 million pounds of ethylene per day, or 4.3 billion pounds annually.

HDPE Project

INEOS Olefins & Polymers USA and Sasol have broken ground on their high-density polyethylene (HDPE) manufacturing joint venture at the INEOS Battleground Manufacturing Complex in La Porte, Texas. The facility will produce 470 kilotons per year of bimodal HDPE using Innovene S process technology licensed from INEOS Technologies. The intention is to produce a limited number of grades allowing high grade efficiencies. INEOS will operate the 50/50 joint venture. The plant is expected to start up in 2016.

Gasifier Vessel

Linde North America has completed installation of the gasifier vessel, a significant step in the construction of its new gasification train at its La Porte, Texas facility. The plant is part of a more than $250 million investment that also includes a state-of-the-art air separation unit, which is also under construction. The gasification plant is scheduled to come on-stream early in 2015. The new gasifier will convert natural gas into syngas. The air separation unit is slated to be operational in December 2014. The plant will also produce liquid oxygen, nitrogen and argon.

World

Heat Exchanger Order

Alfa Laval has won an order to supply Alfa Laval Packinox heat exchangers to a petrochemical plant in South Korea. The order has a value of approximately SEK 85 million and delivery is scheduled for 2015. The heat exchangers will be used in the production of mixed Xylenes, ingredients in the manufacturing of synthetic nylons and PET bottles.

Maintenance

Yanbu National Petrochemicals Co will be shutting its ethylene glycol plant in April 2015 for between 35 and 60 days for planned maintenance. The financial impact on the company is estimated to be around $119.9 million.

Investment

Bharat Petroleum Corp will invest $741.44 million to diversify into the petrochemicals business, moving the state refiner beyond refining and retailing to boost margins. The company will produce niche petrochemical products that are predominantly imported into India at its Kochi refinery using propylene that will be available once the ongoing refinery expansion is completed. The company plans to boost capacity at its Kochi refinery to 310,000 barrels/day from the current 190,000 barrels/day by May 2016. The project proposal is submitted and awaiting environmental clearance. The petrochemical unit is expected to come on stream during financial year 2018-2019.

Guidance Notes On Buried Piping

Dec 15 2014 03:24 AM

Dear All,

Most process engineers should try to understand basic concepts of piping installation along with routine process design calculations related to piping such as pressure drop, velocity and erosion / corrosion limits for various pipe metallurgies.

Today's blog entry provides some guidance on buried or underground pipe installation.

Piping should not be buried or installed underground when it can be reasonably avoided.

Major applications for buried piping are generally cross-country pipelines where security and safety justify burial. Here security implies the difficulty of sabotage and intentional damage to a buried pipeline vis-a-vis an aboveground pipeline. Safety implies the safety of the surroundings (environment / population centers) due to unintentional or accidental damage of the buried pipeline vis-a-vis an aboveground pipeline.

Other major applications for buried piping are firewater piping, critical piping running across the entire plant installation with certain sections aboveground and certain sections underground. Underground sections would generally be routine movement areas including road and rail crossings.

Underground firewater piping has gained popularity in recent years as explained below:

- Above ground carbon steel or lined carbon steel pipes filled with untreated water are a source of corrosion and undermine the integrity of the fire water system and are slowly being replaced with plastic pipes (HDPE / GRE etc.) which are much more corrosion resistant.

-Plastic pipes although having higher corrosion resistance to untreated water have much lower mechanical strength compared to carbon steel pipes when subjected to forces such as impact and vibration.

-To maintain mechanical integrity of the plastic pipe, burying the firewater pipe and running across the installation becomes a logical option.

- Option of having firewater piping with exotic metallurgies (Stainless steels / Cupro-Nickel etc.) is not an economical choice. It is important to note that common austenitic stainless steels are susceptible to chloride stress corrosion cracking in water environment with high chloride content.

Problems Associated with Buried Piping:

- Buried Steel pipes are subjected to external corrosion despite mitigating measures such as external coating and cathodic protection

-Draining, cleaning of buried pipes is difficult compared to aboveground pipe.

-Leak detection and repair of of buried pipe is a difficult and expensive exercise. Although modern buried pipeline leak detection systems are available now, they are very expensive to install.

-Buried pipes are almost always subject to mechanical damage if being excavated or if any excavation work is being carried out in close vicinity.

-Buried pipes carrying hot fluids and subject to thermal expansion can cause pipe deformation and / or partial / total removal of the external protective coating if applied.

Corrosion Protection of Buried Pipes:

All buried steel piping with the possible exception of cast iron piping should be protected from soil corrsion with a suitable exteranl coating.

Following is the list of the most commonly used acceptable coatings and wrappings with approximate pipe surface temperature limitations:

-Fusion Bonded Epoxy (< 93°C)
-Liquid epoxies (< 107°C)
-Extruded Plastic (< 82°C)
-Tape Wraps (< 60°C) (higher temperatures applicable in case of high temperature thermosetting tape)
-Coal Tar Enamels (< 60°C)

When small quantities of buried piping require protection, tape wrap is often selected because it is relatively inexpensive and easy to apply in the field. However, it is often the least reliable coating, with poor performance in water- and oil-saturated soils, and in cyclic temperature service. It requires proper pipe surface preparation and is easily applied improperly.

Protection for coated pipe at weld joints and tie-ins is provided by field-applied fusion bonded epoxy, shrink sleeves of polyethylene, heat-cured liquid epoxy, or tape wrap.

Aside from the type of coating selected, proper application of the coating and maintenance of its integrity are required for proper installation of a protected line. Because success or failure cannot be determined for an extended time after installation, usually years, attention should be paid to:

-Correct surface preparation for the type of coating used
-Application of the coating to the specified consistency and thickness
-Care in handling and laying to avoid coating damage
-Proper cleaning, priming, and field coating of joints and fittings
-Inspection of coating for any damage and proper repair
-Backfilling and compacting to prevent contact with any material that could damage the coating

Cathodic Protection:

Cathodic protection (CP) can be roughly defined as retarding or preventing the corrosion of a metal by imposing an electrical current flowing to the metal through an electrolyte. In the case of buried piping, the pipe is the metal and the soil is the electrolyte.

Fore more details on cathodic protection refer the following link:

http://en.wikipedia....odic_protection

Cathodic protection is often used with coatings to protect piping. Regardless of the care used in coating and installing buried lines there will often be small pinholes in the coating. A cathodic protection system can protect against corrosion at these points and significantly extend the life of the piping.

Cathodic protection is applied to underground piping as a system. At every location where cathodically protected pipe leaves the soil (or water) it must be electrically isolated from the aboveground continuation of the line if the continuation is not part of the CP system. This is done with an insulating flange kit (or insulating union on small diameter pipe) that uses electrically insulating bolt sleeves, nut washers, and sealing gasket in a conventional flange makeup.

Cross country steel pipelines, and steel submarine piping are the principal users of cathodic protection.

This is all folks, as a brief synopsis on the subject of buried pipes and I look forward to comments on the subject from the members of Cheresources.

Regards,
Ankur.

Chexpress - December 3, 2014

Dec 03 2014 02:16 PM

North America

Merger

Kinder Morgan, Inc. has completed its acquisition of the outstanding equity securities of Kinder Morgan Energy Partners, L.P., Kinder Morgan Management, LLC and El Paso Pipeline Partners, L.P. The approximately $76 billion transaction was initially announced earlier this year on August 10. Kinder Morgan, Inc. is the largest energy infrastructure company in North America. It owns an interest in or operates approximately 80,000 miles of pipelines and 180 terminals. The company’s pipelines transport natural gas, gasoline, crude oil, CO2 and other products, and its terminals store petroleum products and chemicals, and handle bulk materials like coal and petroleum coke.

Approval

British Columbia approved a liquefied natural gas export terminal being developed by Petronas, along with two pipelines to service Canada’s LNG industry. A federal environmental review of Petronas’ Pacific NorthWest LNG project is continuing, with Petronas expected to make a final investment decision on the $11 billion facility before the end of the year. In addition to the federal review, Petronas must now meet eight social and environmental conditions set out in the provincial approval and secure various permits from all levels of government. Petronas is also in the process of negotiating with aboriginal communities and refining its terminal design plans to mitigate the impact on sensitive fish populations.

Acquisition

Halliburton is buying Baker Hughes in a cash-and-stock deal worth $34.6 billion. Global oil prices have fallen 31 percent over the past 5 months to levels not seen in four years, which has forced the industry to cut costs by delaying or scaling back drilling. This means less work for companies that manage oil and gas fields for energy companies like Halliburton and Baker Hughes. It is believed that the combined company will be able to reduce costs by $2 billion a year.

World

Biosludge

Sasol has opened an industrial plant that converts toxic waste sludge into fertilizer. The Secunda project in South Africa’s Mpumalanga province produces synthetic fuels like petrol and gas by burning coal, a process that leaves behind 80,000 tons/year of toxic waste (or biosludge). Sasol used to burn the waste or send it to a landfill. Now, the new waste-to-fertilizer plant at Secunda will use bacteria and fungi micro-organisms to break down the biosludge and convert it into organic compost, which can be recycled as fertilizer.

Restart

An affiliate of Saudi International Petrochemical Co (Sipchem) has restarted a methanol plant after scheduled maintenance. The International Methanol Co. (IMC) plant, which produces 967,000 tons of methanol/year, was shut on Nov. 3 for three weeks for maintenance and repairs. IMC Is 65 percent owned by Sipchem, while a group of Japanese companies hold the rest.

Thinner-diaper technology

BASF will invest $624 million over the next two years in upgrading its production plants to make superabsorbers that allow for thinner diapers. The market launch of the new generation of superabsorbers will start at the end of 2016. Superabsorbent polymers can absorb and retain a large amount of liquid and are the main component in baby diapers, incontinence products and feminine hygiene products.

Investment

Ineos announced plans to invest $1 billion in shale gas exploration in Britain. The investment is subject to Ineos winning UK shale gas licenses currently being decided. The investment would mainly cover exploration costs.

Chexpress - November 12, 2014

Nov 12 2014 08:23 AM

North America

Proposed Cracker

Shell Chemical LP has exercised its option to purchase a Monaca, Pennsylvania site where it has proposed building an ethylene cracker. Shell is purchasing Horsehead Holding Co.’s former zinc smelter site. Shell is performing a multi-year review of the site, including environmental analysis, engineering design studies, evaluation of ethane supply and economic viability. A closing date for the purchase has yet to be established.

Furnace Supply

Sasol awarded Technip a contract to provide engineering and procurement for eight proprietary Ultra Selective Conversion (USC) furnaces for an ethane cracker and derivatives complex to be located in Lake Charles, Louisiana. The award follows Sasol’s selection of Technip’s ethylene technology and front end engineering design (FEED) for the cracker, which will produce an estimated 1.5 million tons/year of ethylene.

Ethane Cracker Design Contract

Technip has entered into a contract to supply its ethylene technology and process design package (PDP) for an ethane cracker for the proposed ASCENT (Appalachian Shale Cracker Enterprise) petrochemical complex currently being evaluated by Odebrecht and Braskem in Parkersburg, West Virginia. By using ethane from shale gas, this cracker will produce ethylene to be used in polyethylene plants.

Capacity Expansion

Chevron Phillips Chemical Company LP has launched a study to expand its low viscosity polyalphaolefins (PAO) capacity by 10,000 metric tons/year of capacity at is Cedar Bayou plant in Baytown, Texas. The plant’s current capacity is 48,000 metric tons/year. The company has filed the necessary environmental notifications with the Texas Commission on Environmental Quality (TCEQ). Final project approval is likely to be sought in the second quarter of 2015, with project completion targeted for 2016.

World

Construction Postponed

SOCAR has delayed the completion of a major plant to process oil, gas and petrochemicals worth up to $16.5 billion near Baku, Azerbaijan by four years until 2030 due to a lack of funds. The construction of a gas processing plant and petrochemicals plant worth $8.45 billion is now due to be completed by 2020 instead of 2017, while an oil refinery worth $8 billion is expected to be completed by 2030 and not 2026. The new complex will replace SOCAR’s two ageing downstream refineries (Baku Oil Refinery and Oil Refinery Azerneftyag).

Funding

PTT Pcl will finalize its funding plan for a $22 billion refinery and petrochemical complex in Vietnam in the third quarter of 2015. PTT will join with Saudi Aramco to develop the project, which includes a 400,000 barrel/day refinery and an olefins and aromatic petrochemical plant making 5 million tons/year. PTT and Aramco will each own 40 percent of the project, with the Vietnamese government holding the remaining 20 percent. Construction could begin in 2016 with operations then starting in 2021.

Maintenance

An affiliate of Saudi International Petrochemical Co (Sipchem) will shut a methanol plant for around three weeks for maintenance and some repairs. The shutdown will boost efficiency and production. As a result of the outage, Sipchem will incur losses of $9.3 million. The company has taken precautions to alleviate the impact of the shutdown on its customers.

Determining Diesel Transfer Pump Capacity For Diesel Engines And Generators

Nov 08 2014 04:36 AM

Dear All,

Often process engineers are asked to design a diesel storage and transfer system for diesel engines and diesel power generators. Where to start is often a question among process engineers. There has to be a design basis for designing such a system. Today's blog entry addresses the design basis for design of a diesel storage and transfer system along with a solved example for such a design. Readers of my blog are welcome to convert this information into an excel spreadsheet calculation and share.

Consider the following calculation example:

Inputs:
No. of Installed DGs: 3
No. of Working DGs: 2
Rating per DG: 1500 kW
Diesel Filling time: 1 hour (to Diesel day tank)
Transfer Pump Design Flow factor: 1.1
Diesel Day tank storage basis: 24 hours
Usable Day tank volume factor = 0.95
Main Diesel Storage Tank hold-up basis = 7 days (Note 1)

Calculations:
Diesel Flow per DG = 0.4 m³/h (from table above with vlookup function)
Total Diesel flow = 0.8 m³/h (0.4*2)
Day tank theoretical capacity per DG = 9.6 m³ (0.4*24)
Day tank working capacity per DG = 10.11 m³ (9.6 / 0.95)
Max. Diesel Consumed per day = 19.2 m³ (9.6*2) where 2 is the no. of working DGs
Max. Diesel Rate = 19.2 m³/h (19.2 / 1) where 1 is the Diesel filling time in hours
Diesel Pump Design Capacity = 21.12 m³/h (19.2*1.1)
Main Diesel Tank working Capacity = 134.4 m³ (19.2*7)

Notes:
1. For on-shore installations the total diesel storage is often considered for 7 days and for off-shore installation it is generally considered as 15 days.
2. The above example calculation considers a separate main storage tank and separate individual day tanks for individual DG sets. In many instances, the individual day tank for DGs may have a hold-up for 8 to 12 hours instead of 24 hours which would require 2 fillings per day for 12 hours hold-up and 3 fillings for 8 hours hold-up

Hope readers of my blog find this blog entry interesting and I look forward to their comments.

Regards,
Ankur

Chexpress - October 29, 2014

Oct 29 2014 07:03 AM

North America

Ethane Cracker

Sasol will build an $8.1 billion plant in Lake Charles, Louisiana. The plant will convert natural gas into plastics ingredient ethylene as part of the biggest overseas investment by a South African company. This effort is expected to be followed by plans to build an integrated gas-to-liquids and chemicals facility there too. The planned cracker will produce 1.5 million tons of ethylene/year for use in plastics and chemicals. Sasol will invest an additional $800 million in infrastructure and utility improvements, as well as on land acquisition.

Contract

Fluor Technip Integrated was awarded a contract to continue to support Sasol with the detailed design, procurement and construction of its ethane cracker and derivatives complex in Westlake, Louisiana (as outlined above). The new complex will be constructed adjacent to Sasol’s existing facility. Flour Technip Integrated will be responsible for the 1.5 million tons/year ethane cracker, downstream derivative units and associated utilities, offsites and infrastructure work. Construction is expected to be complete in 2018.

Capacity Expansion

Westlake Chemical Corporation will expand its ethylene capacity and make other capital improvements in Lake Charles, Louisiana with an investment of more than $330 million. This expansion is expected to be completed in late 2015 or early 2016 and will increase ethane-based ethylene capacity at the plant by approximately 250 million pounds/year.

World

Compounding Deal

Celanese Japan Limited and Setsunakasei Co. Ltd. (Setsunan) have signed a letter of intent to pursue an agreement whereby Setsunan will compound Celanese engineered polymers in Setsunan’s facilities in Japan. Celanese engineering polymers are used in a wide array of applications across many industries, including automotive, consumer and industrial segments. These polymers may be processed by injection molding, extrusion, compression, molding, rotational casting or blow molding.

LNG Project

Eni has signed a cooperation agreement with Korea Gas Corporation (Kogas) to further strengthen their relationship in a number of areas, particularly in the upstream and LNG (liquefied natural gas) sectors. The agreement allows the companies to jointly pursue opportunities worldwide. The companies expect the agreement to facilitate the LNG development of Area 4 in Mozambique where Eni is operator with a 50 percent interest, Kogas, Galp Energia and ENH partners in the agreement with 10 percent interest each, and CNPC with 20 percent indirect participation. Area 4’s total resources are estimated to be approximately 85 trillion cubic feet of gas in place and ready to enter in the development phase in 2015.

Refining Capacity Boost

PDVSA plans to invest $20 billion to expand its domestic refining capacity in Venezuela by 20 percent. PDVSA plans to add 265,000 barrels/day of refining capacity to the current 1.3 million barrels/day. The plans include doubling the capacity of the 146,000 barrels/day El Palito facility and boosting capacity of the 187,000 barrels/day Puerto la Cruz refinery by 20,000 to 25,000 barrels/day. The plans also involve optimizing the operations of the Paraguana Refining Center.

Chexpress - October 15, 2014

Oct 15 2014 06:41 AM

North America

Ammonia Plant

Linde Engineering North America (LENA) is building an ammonia plant for J.R. Simplot Company adjacent to Simplot’s existing phosphate fertilizer complex in Rock Springs, Wyoming. The 600 tons/day plant will supply both the Rock Springs and Pocatello, Idaho phosphate fertilizer production locations while also providing the capacity to meet Simplot’s next phase of anticipated phosphate expansion plans at its Rock Springs location. It is expected to take two years to complete the new plant.

Acquisition

Boardwalk Pipeline Partners, LP has completed the acquisition of Chevron Petrochemical Pipeline LLC from Chevron Pipe Line Company. Chevron Petrochemical Pipeline owned the Evangeline ethylene pipeline system. Evangeline will be operated by Boardwalk Louisiana Midstream (BLM), a subsidiary of Boardwalk. The Evangeline system is a 176-mile interstate pipeline capable of transporting approximately 2.6 billion pounds of ethylene/year and is supported by long-term, fee-based contracts. The pipeline transports ethylene between Port Neches, Texas and Baton Rouge, Louisiana.

Specialty Pipe

LyondellBasell’s 3,900-acre petrochemical facility is undergoing an expansion to increase production of ethylene units as well as propylene, butadiene and benzene. Tioga was selected by KBR, the expansion contractor, as its supplier of choice over several other bidders for the LyondellBasell ethanol plant expansion project. The project requires timely delivery of specialty pipes for chemical composition made of certain percentages and composition of material outside of the industry ASTM standards.

Apprenticeship Program

The Dow Chemical Company will launch a U.S. Apprenticeship pilot program at various Dow sites across the nation in 2015. Dow’s U.S. Apprenticeship program will offer participants two to four years of training and on-the-job experience in some of the most sought after and highest earning technical specialties in the industry. Through partnerships between Dow and local community colleges, the program will combine classroom training and hands-on learning to build skills and experience. Upon program completion, apprentices will be evaluated for employment opportunities at Dow. Dow will pilot the program at five of tis manufacturing sites in Texas (Freeport, Bayport, Deer Park, Seadrift and Texas City) as well as at its manufacturing sites in Pittsburg, California and the Chicago area. The company expects to hire approximately 60 apprentices for the pilot program in 2015, offering training for roles such as Chemical Process Operators, Instrumentation & Equipment Technicians and Analyzer Technicians.

World

Polypropylene Unit

CB&I has been awarded a contract by Shenhua Ningxia Coal Industry Group Co. Ltd. for the license and engineering design of a polypropylene unit to be built in Lingwu, China. The unit will use CB&I’s Novolen technology to produce 600,000 metric tons/year of polypropylene. There are already two units using this technology on the site and at the completion of the third unit, the capacity of the site will be increased to 1.6 million metric tons/year and the plant will be able to produce the full range of polypropylene grades.

Pipelines

Kashagan will have to spend up to another $3.6 billion to replace leaking oil and gas pipelines, which could also delay the restart of production. Production at the Kashagan reservoir, the world’s biggest oil find in recent times, started in September 2013, but was halted just a few weeks later after the discovery of gas leaks in the $50 billion project’s pipeline network. Replacing the pipelines at the Kazakhstan oilfield will cost between $1.6 billion and $3.6 billion. The final cost of the replacement mainly depends on the resistance to corrosion of the pipes used in laying the new pipelines.

Pipeline

China National Petroleum Corp (CNPC) has received government approval for the design of the Chinese section of a giant pipeline that is due to ship $400 billion worth of Russian natural gas to China. According to the initial designs, the pipeline will start from Heihe city and run through the provinces of Jilin, Inner Mongolia, Liaoning, Hebei, Tianjin Municipality, Shandong, and Jiangsu to reach Shanghai. Construction of the Chinese section will start in the first half of next year and is slated to be complete in 2018.

Selection And Sizing Of Marine Loading Arms For Petroleum (Black / White Oil) Products

Oct 04 2014 04:12 AM

Dear All,

Todya's blog entry provides a procedure for selection / sizing of marine loading arms

Vessel / Tanker Design Discharge Capacity (Figure 1)

Oil Tanker Manifold Diameters

Loading Arm size should not be larger than a maximum of two sizes of the the ships manifold diameter. A smaller size loading arm compared to the ship's manifold diameter is acceptable using a reducing spool piece.

Flow Rate Vs No. of Marine Loading Arms (Figure 2)
Based on limiting flow velocity of 11 m/s (36 ft/s)

Maximum Marine Arm Loading Flow Rates
Based on Limiting Flow Velocity of 11 m/s (36 ft/s)

Example Calculation

Inputs
Max Vessel Size = 100,000 DWT
Product Viscosity = Heavy
Pump Type = Centrifugal

Outputs
bbls/hr/DWT = 0.6 (From Figure1)
Correction factor = 0.88
Max. Discharge Rate = 52,800 bbls/hr
Max. Arm Size = 16 inch
No. of Arms = 2 (From Figure 2)

Note:
Part III, Section 2-Guidelines (page 40) of the document "Design & Construction Specification for Marine Loading Arms" which is issued as a standard for MLAs by the "Oil Comapnies and International Marine Forum" with the acronym "OCIMF" recommends a maximum velocity of 12 m/s through marine loading arms.

Looking forward to hear comments from the members of the "Cheresources" community.

Regards,
Ankur.

Chexpress - October 1, 2014

Oct 01 2014 07:25 PM

North America

Unit Sale

Dow Chemical Co. has started the process of selling its epoxy and chlorine businesses. The company has hired Goldman Sachs Group Inc. and Barclays Plc to manage the process. Combined, the epoxy and chlorine businesses have annual earnings before interest, taxes, depreciation and amortization of close to $500 million.

Expansion

LyondellBasell is evaluating a further expansion project at its petrochemical plant in Channelview, Texas. The expansion would potentially add up to 550 million pounds/year of ethylene capacity. Preliminary engineering work is underway to assess expansion feasibility and if it proceeds, the project is expected to be completed in 2017. This expansion effort would be in addition to work already underway to install two large cracking furnaces at the site that are slated to increase production by 250 million pounds/year when construction is complete in early 2015.

Donation

General Electric Co. will give Penn State University up to $10 million to create a new center for natural gas industry research. The money will support research projects, equipment, and undergraduate, graduate, and postdoctoral fellowships at The Center for Collaborative Research on Intelligent Natural Gas Supply Systems. The new center will include faculty from the Smeal College of Business, Earth and Mineral Sciences, Engineering, and Information Sciences and Technology. The money will be donated over the next five years and earmarked for different uses. The company will also have engineers in residence to work with faculty and students.

World

Plastics Plant

Saudi International Petrochemical Co. (Sipchem) has started trial operations of a new plant in Riyadh, Saudi Arabia along with Hanwha Chemical. The plant has an annual production capacity of 1,000 tons of plastic moulds. The plant is estimated to have cost $29.3 million to build. Sipchem owns 75 percent of the joint venture – Saudi Specialty Products Co. – while Hanwha owns the remaining 25 percent.

Hydrocarbon Fluid Production

ExxonMobil Chemical is increasing production of its high performance hydrocarbon fluids by about 10 percent through expansion projects at its Singapore and Antwerp, Belgium facilities. The additional capacity will begin producing by mid-2015 and be complete in 2016. The expansion projects are in progress and build on other recently announced investment projects in the two facilities.
ExxonMobil to Boost Hydrocarbon Fluid Production at Antwerp, Singapore

Exit

Clorox is shutting down all operations in Venezuela, citing restrictions by the government, supply disruptions, and economic uncertainty as the reasons. Clorox said that for almost three years, its affiliate, Corporación Clorox de Venezuela S.A., had to sell more than two-thirds of its products at prices frozen by the Venezuelan government. During that same time span, there was a sharp rise in inflation that resulted in significantly higher costs for Clorox. After repeated meetings with government authorities, the company had expected significant price hikes would be allowed earlier this year. The price increases that were approved were nowhere near sufficient and Clorox said it would be forced to continue selling products at a loss. The company is now looking to sell its assets in Venezuela.

Acquisition

Siemens AG has reached a deal to acquire oilfield equipment maker Dresser-Rand for $7.6 billion. Dresser-Rand’s portfolio of compressors, steam, and gas turbines and engines complements Siemens’ existing offerings mainly in the global oil and gas and power generation businesses. Siemens will operate Dresser-Rand as its oil and gas business under the Dresser-Rand brand name and retain its executive team.

Chexpress - September 17, 2014

Sep 17 2014 06:27 AM

North America

Settlement

Occidental Chemical Corp. has agreed to pay New Jersey $190 million as part of a settlement to clean up the polluted Passaic River. The agreement is subject to approval by New Jersey Superior Court. Occidental Chemical bought a Newark factory once owned by Shamrock Chemicals Co., which dumped cancer-causing dioxin into the river during the manufacturing of the Vietnam War-era defoliant Agent Orange. Several companies associated with the former Diamond Shamrock site were named in the lawsuit aimed at cleaning up the river, with Occidental being the last to settle.

Expansion

The Oilfield Technology Group (OTG) of Momentive Specialty Chemicals Inc. has expanded its triazine production plant in Edmonton, Alberta, Canada. The investment has increased raw and finished materials storage, modified the plant to provide increased capacity and redundancy, enabled flammable triazine production capability and dedication storage, and optimized truck loading for increased production flexibility and decreased loading times.

Fertilizer Plant

CHS Inc. will construct a fertilizer manufacturing plant in Spiritwood, North Dakota. The approximately $3 billion plant is intended to be fully operational in the first half of 2018. When complete, the plant will employ 160-180 people. The plant will produce more than 2,400 tons of ammonia daily, which will be further converted to urea, UAN and Diesel Exhaust Fuel (DEF). The majority of the nitrogen products from the plant will server farmer-owned cooperatives and independent farm supply retailers within a 200-mile radius of the plant.

Acquisition

Boardwalk Pipeline Partners has entered into a definitive agreement with Chevron Pipe Line Company to acquire Chevron Petrochemical Pipeline LLC, which owns the Evangeline ethylene pipeline system. The $295 million deal is subject to customary adjustments and closing conditions, but is expected to close in the fourth quarter of 2014. After the acquisition, Evangeline will be operated by Boardwalk Louisiana Midstream (BLM), a subsidiary of Boardwalk. The Evangeline system is a 176-mile interstate pipeline capable of transporting approximately 2.6 billion pounds of ethylene per year between Port Neches, Texas and Baton Rouge, Louisiana.

World

Restart

Mitsui Chemicals Inc. has restarted its 612,000 ton/year naphtha cracker at its Ichihara, Japan plant. The restart followed repair work on an unspecified problem.

Petrochemical Project

PPT has joined with Saudi Aramco to submit a proposal to the Vietnamese government to build a $22 billion refinery and petrochemical complex in Vietnam. PPT and Aramco will each own 40 percent of the project with the Vietnamese government holding the remaining 20 percent. The project includes an olefins and aromatic petrochemical plant with a combined capacity of 5 million tons/year. It is expected to take six to seven years before the complex will be fully operational.

Expansion

PetroRabigh’s founding shareholders have formally invited banks to provide financing for the $8.5 billion expansion of its petrochemicals complex in Saudi Arabia. PetroRabigh is a joint venture between Saudi Aramco and Sumitomo Chemical. The requests for proposals were issued to local and international banks, with financing of the expansion to be split between conventional loans and sharia-compliant facilities. The exists plant can produce 18 million tons of refined projects and 2.4 million tons of petrochemical products. The new facility – Rabigh II – is to be an expansion of the existing petrochemical plant, increasing output and introducing higher-margin products.

Flare Dispersion Analysis - Frequently Asked Questions (Faqs)

Sep 08 2014 10:51 AM

Q1. What is Flare Dispersion Analysis?
A1. Flare dispersion analysis is a study of the dispersion of toxic and / or flammable pollutants (primarily gaseous) from a flare, either a ground or elevated flare.

Q2. Is it necessary to perform a flare dispersion analysis?
A2. Yes, it has now become mandatory in most parts of the world when a new industrial unit which requires a flare to burn waste gases requires to be set up and an environmental clearance is required from the local government for establishing the unit.

Q3. Is flare dispersion study required for existing old industrial units?
A3. This depends on the local laws and regulations related to environmental safety for the concerned industrial unit. From a moral and ethical viewpoint, it becomes obligatory for any organization to conduct not only a flare dispersion study for a new industrial unit it owns but also for old industrial units which may be more prone to emitting harmful pollutants to the atmosphere. Changing demographics make a compelling reason for periodic flare dispersion studies over the lifetime of the industrial unit. Most advanced nations have now made it compulsory for such kind of studies whether it be a new industrial unit, license renewal for an existing old unit or due to the changing demographics around a under construction / existing industrial unit.

Q4. Which are the reputed statutory/regulatory and guiding agencies which provide guidelines and assistance in conducting flare dispersion studies?
A4. Refer the list below:
a. United States Environmental Protection Agency (EPA)
http://www.epa.gov/
b. European Environment Agency
http://www.eea.europa.eu/
c. Oil Industry Safety Directorate (OISD) - India
http://oisd.gov.in/
d. Ministry of the Environment – Government of Japan
http://www.env.go.jp/en/
e. Environment Agency – Gov. UK
https://www.gov.uk/g...ironment-agency

Q5. What kind of dangerous pollutants are normally encountered from an industrial flare?
A5. Some of the most common pollutants are listed below:
a. SO₂ (Sulfur Dioxide)
b. NO₂ (Nitrogen oxide)
c. CO (Carbon monoxide)
d. CO₂ (Carbon Dioxide) (Greenhouse gas)
e. Unburnt Hydrocarbons
f. Suspended Particulate Matter (SPM)
g. H₂S (Hydrogen Sulfide)

Q6. What basic scenarios need to be considered when doing a flare dispersion analysis?
A6. Flares may operate under different conditions depending on the type of industrial unit where the flare is installed. However, the basic three scenarios that need to be considered for a flare dispersion study are as follows:
a. Normal flaring under normal plant / unit operating conditions
b. Emergency flaring under emergency or plant / unit upset conditions
c. Flameout when combustion is not taking place and cold venting from the flare occurs

Q7. Which is the most well known mathematical model used for flare dispersion studies?
A7. The most well known mathematical model widely used for air dispersion modeling is the “Gaussian Dispersion Model”. Refer the link below:
http://en.wikipedia....ersion_modeling
http://petrowiki.org...isposal_systems

Q8. Which are the well known commercial software that can be utilized for flare dispersion studies?
A8. “PHAST” from DNV, “FlareSim” from Softbit Consultants, and “FRED” from Shell Global Solutions

Q9. Which other software can be used for flare modeling?
A.9 A freeware "SCREEN3" for point source (flare) modeling to estimate the ground level concentration can be found at the following link:
http://www.weblakes....roducts/screen/
Refer the links below for some other commonly used software:
http://www.weblakes.....html#emissions
http://www.ehssoftse.../air_airmod.htm

Look forward to comments and observations from the readers of my blog.

Regards,
Ankur.

Chexpress - September 3, 2014

Sep 03 2014 09:56 PM

North America

PO/TBA Plant

LyondellBasell plans to build a propylene oxide (PO)/tertiary butyl alcohol (TBA) plant on the U.S. Gulf Coast with an annual capacity of 900 million pounds of PO and 2 billion pounds of TBA and its derivatives. The company expects to have the plant operational in 2019. The exact location of the plant has not been finalized.

Acquisition

NanoH20, a manufacturer of efficient and cost-effective reverse osmosis membranes for seawater desalination, has changed its operating name to LG NanoH20 Inc. The change follows the company’s recent acquisition by LG Chem, Ltd.

Chemical Complex

Sasol Ltd. has cleared a key permitting hurdle needed to begin construction on a $16-$21 billion complex near Lake Charles, Louisiana. The U.S. Army Corp of Engineers approved the company’s wetland modification permit to build gas-to-liquids and ethane cracker facilities. Construction for the ethane cracker is expected to begin this year, with operations beginning in 2017. In 2016, Sasol is expected to begin construction of a gas-to-liquids facility, which will convert natural gas into diesel fuel and other liquids with a capacity of 96,000 barrels/day, opening in 2019.

Product Testing Facility

Bayer HealthCare Pharmaceuticals could spend $100 million to build a product testing facility and three buildings in Berkeley, California. A final decision on whether to move forward with the project won’t come until later this year. The potential 80,000-square-foot, three-story structure would shift testing of Bayer’s next-generation hemophilia A treatment there from the company’s main campus. Construction on the site could begin as soon as January and last two years.

World

Acquisition

3M has completed its acquisition through Sumitomo 3M Ltd. of Sumitomo Electric Industries Ltd.’s 25 percent interest in Sumitomo 3M Ltd. for approximately $865 million. 3M is now the sole owner of the business, which will be known as 3M Japan Ltd.

Units Merge

Samsung Group will merge its shipbuilding and engineering units. Samsung Heavy Industries Co. will combine with Samsung Engineering Co. before the end of the year. A company spokesperson said this is the start of more restructuring that’s to be expected from the heavy-industry companies within the Samsung Group.

Petrochemical Complex

PPT Pcl is making a proposal to the Vietnamese government to build a $20 billion refinery and petrochemical complex. This proposal is revised down from an earlier project discussed two years ago. The complex has been designed to help meet Vietnam’s domestic demand for oil products and boost its exports. The $18.8 billion project now includes a 400,000 barrels/day refinery and olefins and aromatic petrochemical plants. The construction of the refinery is scheduled to be completed by 2021, with most of its products serving domestic demand in Vietnam. The petrochemical complex will have an annual production capacity of 2.9 million tons of olefins and 2 million tons of aromatic products, most of which will be exported.

Chexpress - August 20, 2014

Aug 20 2014 06:47 AM

North America

Ethane Cracker Project

Jacobs Engineering Group Inc. has been awarded a contract from ExxonMobil Chemical Company to provide engineering, procurement and construction services as part of a multi-billion dollar ethane cracker project in ExxonMobil’s Baytown, Texas complex and associated premium product facilities in Mont Belvieu, Texas. Jacobs is also working on the interconnectivity of the two sites.

Ethane

Navigator Holdings Ltd. has signed a long-term shipping agreement for one of its 35,000 cubic meter ethylene/ethane capable semi-refrigerated liquefied gas carriers currently being built in Jiangnan Shipyard, China. The ten-year time charter with Borealis is planned to commence in late 2016. The charter will transport ethane from the Marcus Hook terminal operated by Sunoco Logistics in the U.S. to Borealis’ cracker in Stenungsund, Sweden.

Petchem Business Unit

The Linde Group has added a petrochemical plant business unit to its Engineering Division offices in Houston, Texas. The new regional business unit will serve petrochemical customers on a wide range of projects, from consulting and technical support, revamp and expansion studies to EPC (engineering, procurement and construction) execution of mid-size projects. In addition, it will play a role in the project execution of mega projects.

World

Fertilizer Plant

Mitsubishi Corp. and Gap Insaat have laid the foundation of a $1.3 billion plant to produce carbamide in Turkmenistan. The country plans to gain added value by using its natural gas to produce the fertilizer for export. The new plant will process natural gas to produce 1.1 million tons of carbamide (also known as urea) annually. It will employ 1,000 workers and be built near the Garabogaz Bay in the Caspian Sea.

Pipeline Stopped

Colombia’s Bicentenario crude oil pipeline has been shut down after being damaged in a bombing blamed on leftist rebels. The attack caused a huge fire, but no injuries or fatalities. The 230-kilometer pipeline has the capacity to transport 110,000 barrels/day from the Eastern Plains to the Cano Limon-Covenas pipeline. The pipeline was ruptured, oil was spilled and there was a fire.

[h2_header]Lower Output/h2_header]

Neste Oil has been forced to lower output at its refinery in Porvoo, Finland due to damage at the site’s hydrogen plant. Unit repair could take several weeks. The company said that the incident was not expected to harm deliveries that already have contracts.

International Pump Users Symposia

Aug 11 2014 12:49 PM

Below is an important message from Art to all community members:

I’ve invested some time in downloading and compiling a listing of all the documents and printed information that has been presented in the proceedings of the Texas A&M University International Pump Users Symposia that began in 1984. I have prepared this material in order to facilitate the downloading of pump information that I consider as invaluable and important to practicing engineers.

If you glean through some of the titles of the pump-related documents available for immediate downloading, you will notice the same features that caught my attention: these materials are the product of some of the leading world experts in pumping technology. Note that even the great Igor Karassik contributed some valuable input into these conferences before his death in 1995.

I believe that all this material can be of great benefit to our Forums and to the members since all this material is now free for downloading – thanks to my alma mater, Texas A&M. Not only is it freely available, but Texas A&M is paying the cost of storing and issuing it.

Art

Attached File(s)

Listings of TAMU TurboLab Symposiums Proceedings 1984-.xlsx (95.96KB)
Number of downloads: 9410

Some Guidelines For Fixed Bed Ion Exchange Units And Forced Draft Degasifiers

Aug 11 2014 12:26 PM

Dear All,

Boiler feedwater is often obtained from raw water by ion-exchange process utilizing vertical cylindrical vessels which contain ion-exchange resins of various types. These resins remove dissolved salts from the water and replace them with Hydrogen (H⁺) and hydroxyl (OH^-) thus producing pure, mineral free boiler feed quality water.

Resins which replace postively charged ions such as Calcium (Ca⁺⁺), Magnesium (Mg⁺⁺), Sodium (Na⁺) etc. are called "cation" resins and they are regenerated with an acid (sulphuric or hydrochloric) to replace the hydrogen ions which were exchanged for the "cations". More often sulphuric acid is employed for regeneration since it is cheaper than hydrochloric acid and can be stored in carbon steel vessels at ambient temperatures. Hydrochloric acid is more efficient in regeneration than sulphuric acid but storage and handling is expensive and more safety concerns need to be addressed. HCl storage requires elastomer-lined steel vessels and may require fume exposure protection measures such as vent scrubbers due to its high volatility.

Resins which replace negatively charged ions such as Sulphate (SO₄^--), Chloride (Cl^-), Carbonate (CO₃^--) etc. are called anion resins and they are regenerated with caustic (NaOH) to replace the hydroxyl ions which were exchanged by the "anions".

There are weak and strong cation as well as weak and strong anion resins. In general, the weak resins are more efficient in terms of regeneration chemicals (acid or caustic) consumption. However, these resins are also limited in their capability to remove ions. For example, cation removal with Weak Acid Cation (WAC) resin is limited to the amount of Bicarbonate (HCO₃^--) alakalinity in the water; and anion removal is limited to sulfides, chlorides and nitrates in the acidic form when using Weak Base Anion (WBA) resin.

Some cations and anions will slip through the ion exchange system and this is called "leakage".The amount aof leakage is a function of several factors such as:
a. Influent water quality
b. Type of resin employed for the cation and anion exchangers
c. Regeneration chemical type and dosage

There are some design guidelines / parameters for fixed bed ion exchange (excluding packed beds) units and forced draft degasifiers which are as follows:

1. Recommended influent water quality to avoid plugging, fouling and deterioration of resins is provided in the attached table:

2. Flowrates for design of vessel diameter should be kept in the 2 - 15 gpm/ft² (18 gpm/ft² if uniform resin is used) (1.4 - 8.1 L/s/m²) range. The lower limit prevents channeling and the maximum rate allows higher service flows during those periods when other vessels are in regeneration. The maximum flowrate for mixed bed units in polishing service should not exceed 24 gpm/ft² (16.3 L/s/m²).

3. Maximum and minimum bed depths should be 84 in. (2100 mm) and 30 in. (750 mm), respectively.

4. The maximum practical vessel diameter to be considered should be 15 ft (4.6 m).

5. Freeboard (as measured from the top of the exhausted resin bed) should be as follows:
Cation Units – 0.75 x resin bed depth + 42 in. (1050 mm)
Anion Units – 1.0 x resign bed depth + 48 in. (1200 mm)
Mixed Bed Units – 1.0 x resin bed depth + 48 in. (1200 mm)

6. Units should be designed with a maximum of one regeneration per 24 hours.

7. Forced draft degasifiers (also known as Decarbonators) typically reduce free carbon dioxide (CO₂) to 5 ppm and oxygen (O₂) to the 6 - 8 ppm range. The following design guidelines should be considered:
a. Maximum allowable water flowrate should be 17.5 gpm/ft² (11.9 L/s/m²) of cross sectional tower area. Minimum tower height should be 16 ft (4800 mm).

b. The minimum allowable air flowrate should be 3 scfm per gpm (20 L/s per L/s) of design water flow.

c. Storage capacity should not be less than 10 minutes of design throughput rate. Additional storage capacity may be needed for regeneration water requirements.

Design of Ion-Exchange DM water plants is often vendor specific and manufacturers / vendors often provide performance guarantees for outlet DM water quality, regeneration chemicals consumption and efficiency in terms of cubic meter or gallon of Demineralized water produced per cubic meter or gallon of raw water feed to the DM water plant. However, the above mentioned guidelines can help process engineers in evaluating and making an informed judgement on the offers and specifications submitted by the vendors / manufacturers.

Hope readers of my blog find this blog entry informative and I look forward to comments from them.

Regards,
Ankur.

Chexpress - August 6, 2014

Aug 06 2014 06:56 AM

North America

Outage

Dow Chemical Co. could lose more than 200 million pounds of ethylene production as a result of an unplanned outage at its plant in Fort Saskatchewan, Alberta, Canada. The affected ethylene unit went offline on July 22 and back online at low operating rates on August 4. Necessary repairs are being made to bring the operating rates back to full production as quickly as possible.

Investment

Renewable Energy Group plans to spend $15 million in the next 12 months on the company’s Geismar facility, which makes diesel from animal fat. Part of the planned spending will go to make long-term improvements that will allow the plant to use a broader mix of feedstocks. The biofuels plant hasn’t operated since October 2012, and the company has not provided a date for its expected restart. The plant has been renamed REG Geismar.

Asbestos Claims

RPM International plans to spend nearly $800 million as part of a preliminary deal to fund a trust that resolves asbestos personal injury claims tied to a business owned by its Specialty Products Holding Corp. The agreement still needs the approval of the claimants as well as the U.S. Bankruptcy Court.

World

Export

Gunvor Group will start exporting gasoline from its oil terminal in Ust-Luga, Russia. Initial August exports will total around 80,000 tons of gasoline from Surgutneftegaz’s 420,000 barrel/day Kirishi refinery.

Investment

General Electric Co. plans to invest $2 billion in Africa by 2018 to boost infrastructure, worker skills and access to energy. The company’s investments include deals to work on increased electric grid reliability during peak power demands in Algeria and to generate uninterrupted power for the Nigerian National Petroleum Corp’s state oil refinery. GE also extended for five years a “country-to-company” agreement with Nigeria for the development of infrastructure projects, the transfer of skills and technology, and a $1 billion investment in railway and power equipment in Angola.

[h2_header]LNG Project/h2_header]

Inpex Corporation has completed its Ichthys LNG Project’s dredging program in Darwin Harbour, Australia. The program started in 2012 and involved the safe dredging and disposal of more than 565 cubic million feet of rock and sand from the harbor to create a deep shipping channel and berthing area for large liquefied natural gas (LNG), liquefied petroleum gas (LPG) and condensate carriers servicing LNG processing facilities at Bladin Point.

Chexpress - July 23, 2014

Jul 23 2014 07:24 AM

North America

Cogeneration power plant

Mexichem expects to start operating a $650 million cogeneration power plant for Pemex in the first half of 2018. Mexichem won a contract for the Cogeneration Cactus plant in partnership with Enesa Energia. The plant will have preliminary capacity to generate 530 megawatts of power.

Methanol manufacturing facility

Yuhuang Chemical Inc. is opening a methanol manufacturing facility in Louisiana. The $1.85 billion project represents the first major foreign direct investment by a Chinese company in Louisiana. The first phase of construction will begin in 2016, with operations starting by 2018. After the first plant is completed, a second methanol plant will be built to reach an annual capacity of 3 million metric tons of methanol. A third phase will include a methanol derivatives plant that will produce intermediate chemicals.

Acquisition

Albemarle is buying Rockwood Holdings Inc. in a cash-and-stock deal valued at about $6.2 billion. The boards of both companies have approved the deal, which is targeted to close in the first quarter of 2015. It still needs shareholder approval. The combined company would operate under the Albemarle name.

World

Contract

CB&I has been awarded additional contracts by Oman Oil Refineries and Petroleum Industries Company (Orpic) for the Liwa Plastics Projet in Oman. CB&I’s scope of work includes the license and engineering design of three units in addition to the previous award for its ethylene technology and front end engineering and design (FEED) services. CB&I will provide the technology for a new 90,000 metric ton/year high conversion MTBE unit, the technology for a 41,000 metric ton/year butane-1 recovery unit, and the gas processing technology for a new 18 million standard cubic meter/day natural gas liquids extraction plant.

Acquisition

CCP Composites and Polynt Group are planning to combine to create an integrated composite resins producer that will rank number one in Europe and number three globally. Polynt Group has made a firm offer for CCP Composites, which will be presented to the employee representatives concerned as part of the required information and consultation processes. Polynt Group’s offer includes clear undertakings to continue operations sustainably and safeguard existing jobs and employee benefits. The proposed transaction is subject to approval by the relevant antitrust authorities.

Fumes

Fumes from a chemical leak on a ship at the Laem Chabang industrial seaport in Thailand have sickened 139 people, including schoolchildren. Those exposed to the fumes had difficulty breathing, nausea and headaches, and were treated at hospitals. The hazardous flammable liquids leaked when a container fell onto the liquid tank on the Hong Kong ship that was anchored in the port.

Joint venture

Halliburton is entering its first joint venture in China with an affiliate of SPT Energy Group. The venture will focus on hydraulic fracturing and production enhancement services in Xinjiang, China. The companies have worked together for seven years.

Dielectric Constant Data Required For Guided Wave Radar Type Level Transmitters

Jul 22 2014 11:34 AM

Dear All,

One of the most important data required for specifying guided wave radar level transmitters for storage tanks is the Dielectric constant of the stored liquid in the tank.

This data is provided by process engineers. A lot of this data is available directly form various open sources form the internet. Some links are provided below:

http://www.engineeri...nts-d_1263.html

http://krohne.com/en...tric-constants/

However, Dielectric constant can be calculated as a value using refractive index values of the particular liquid. Following is the correlation between refractive index and dielectric constant

Dielectric constant = (Refractive Index)²

or

Refractive Index = (Dielectric Constant)^o.5

It is important to note that the above correlation is good for non-polar liquids. As the liquid deviates from a non-polar behavior to a polar behavior, errors are observed in the values obtained.

Benzene and Toluene are examples of non-polar liquids whereas Glycerol is a polar liquid.

For petroleum distillates a quotient "I" is defined as the refractive index parameter and is related to the refractive index as follows:

I = (n² - 1) / (n² + 2) ---------- (1)

For petroleum fractions having an average molecular wieight below 300 the following correlation is given for the refractive index parameter:

I = 0.328*v^-0.003*SG^0.915---------- (2)

where:
v = Kinematic viscosity of the petroleum fraction, cSt
SG = Specific gravity of the petroleum fraction

Let us take an example for calculation of a diesel :

v = 5 cSt @storage temperature
SG = 0.85 @storage temperature

From eqn (2),

I = 0.28

From eqn (1),

(n² - 1) / (n² + 2) = 0.28

Evaluating "n" the refractive index from above:

n = 1.47

Dielectric constant is refractive index squared or "n²".

Hence,

Dielectric constant = 2.16 (~2.2)

Hope, process engineers who need to provide the dielectric constant for specifying "Guided Wave Radar Level Transmitters" will find this blog entry informative.

Looking forward to hear comments from the readers of my blog.

The reference for the aforementioned equations is provided below as a web link:

http://kosalmath.fil...ydrocarbons.pdf

Regards,
Ankur

Chexpress - July 9, 2014

Jul 09 2014 07:37 AM

North America

Acquisition

Renewable Energy Group has completed the acquisition of Dynamic Fuels, Inc., one of the first renewable diesel biorefineries in the U.S. The Dynamic Fuels facility in Geismar, Louisiana has a 75 million gallon annual production capacity. This was part of a two-part deal. First, Renewable Energy Group acquired most of the assets of Syntroleum Corporation, which included a 50 percent ownership interest in Dynamic Fuels. Shortly after this acquisition in early June, Renewable Energy Group paid $18 million in cash to Tyson Foods for the remaining 50 percent interest.

Capacity

Chevron Phillips Chemical Company LP has received Board of Directors approval and obtained the necessary environmental permit from the Texas Commission of Environmental Quality (TCEQ) to expand normal alpha olefins (NAO) production capacity at its Cedar Bayou plant in Baytown, Texas. This investment will provide an additional 100,000 metric tons/year of capacity. Construction is expected to be completed in July 2015.

Production issue

Oxea Corporation has encountered a significant production issue at its Bay City, Texas facility. Due to a malfunction in the production process, the company has been unable to resume full production. As a result, Oxea made a declaration of force majeure, effective for a number of the company’s products (n/I Butanol, n/I Butyl Acetate, n-Propanol and n-Propyl Acetate). Customer orders are being carefully monitored in an attempt to keep delays to a minimum.

World

Gas study

Sasol is considering a gas-to-liquids plant in Mozambique with Eni SpA and Mozambique’s oil company. The joint pre-feasibility study will assess the viability of such a plant in the region. Eni has found about 75 trillion cubic feet of gas offshore Mozambique in Area 4 of the Rovuma Basin. It is too early to determine how long the study will take or the cost of such a plant.

New facility

Afton Chemical Corporation will expand its global supply network with the addition of a new chemical additive manufacturing facility on Jurong Isalnd, Singapore. The plant will start to produce components in January 2016 to support the next generation of additive solutions. Foster Wheeler Singapore will manage the engineering and construction.

MDI plant

BASF, Huntsman, Shanghai Hua Yi (Group) Company, Shanghai Chlor-Alkali Chemical Co. Ltd. and SINOPEC Group Assets Management Corporation have kicked off the construction of a new plant in Caojing, China. The plant will have an annual production capacity of 240,000 metric tons of crude MDI (diphenylmethane diisocyanate). In addition, the partners plan to build a HCl (hydrogen chloride) recycling plant for the production of chlorine. The facility is expected to start up in 2017. The project is subject to further approvals by the Chinese Ministry of Commerce.

IChemE accreditation

PETRONAS has become the first organization in Malaysia to receive accreditation for its company training scheme by the Institution of Chemical Engineers (IChemE). The company currently employs more than 30,000 employees globally, including 3,500 chemical engineers. It plans to grow rapidly over the next few years and expects it will need additional chemical engineers to support is expansion.

Funding

Saudi Arabian Mining Co. (Ma’aden) has signed a $5 billion financing deal with commercial banks and a state-owned investment fund to back its $7.5 billion phosphate production project in Waad al-Shimal, Saudi Arabia. The project is a joint venture between Ma’aden, Saudi Basic Industries Corp. and Mosaic. The loan agreement will last for 16.5 years and repayments will be made on a semi-annual basis from Dec. 31, 2018. The scheme will have a production capacity of 16 million tons/year of phosphate concentrate, sulfuric acid, phosphoric acid, as well as plants to produce calcium monophosphate and calcium diphosphate. Phosphate production is expected to start in late 2016.

Rotary Screw Compressors - Discussion And Calculations

Jul 03 2014 03:24 PM

Dear All,
Rotary Screw compressors are fast replacing piston type reciprocating compressors all over the world. With advancement in technology of precision machining the helical screws required in screw compressors, they are becoming the first choice for selection where otherwise a piston reciprocating compressor would have been used in earlier days.

I had provided a chart for compressor selection in one of my posts on “Cheresources” at the following link:

http://www.cheresour...3854#entry43854

While this chart is quite handy for compressor selection, latest advancements in technology of screw compressors allow far higher capacities and higher pressure ratios (discharge pressure / suction pressure) compared to what is shown in the chart.

Some general advantages of screw compressors in the category of positive displacement compressors are listed below point wise:

1. Less pulsations or surging of flow compared to piston type compressors since the gas compression process with a rotary screw is a continuous sweeping process.

2. Low mechanical vibrations similar to centrifugal machines compared to piston reciprocating compressors.

3. The inlet or suction volume flow and power consumption increase linearly with the compressor speed at constant discharge pressure.

4. Compared to a centrifugal compressor the inlet or suction volume is nearly constant for variation of pressure ratio or gas molecular weight with no surging limit.

5. The achievable pressure ratio per compressor stage is not limited by the gas molecular weight but limited only by the allowable discharge temperature and mechanical limits of the compressor due to high temperatures.

6. Very high pressure ratios up to 10 per compressor stage can be achieved by liquid injection for cooling.
The pioneers of Screw compressor technology were the Swedish company “Svenska Rotor Maskiner” abbreviated as SRM.

The history of the development of the screw compressor can be found at the following link:

http://www.opcon.se/web/History_4.aspx

SRM main web page can be found at the link provided below:

http://www.opcon.se/web/SRM_EN.aspx

With this blog entry I am also attaching an excel workbook which provides some design equations for calculating the shaft power of oil-free or dry screw compressors. The reference for the design equations is the book “Compressors – Selection and Sizing” by Royce N. Brown which I personally consider amongst the best books for compressors. The book provides equations in USC units which I have converted to SI units. The reference for the rotor diameters and L/d ratios is taken from the reference provided in the link below:

http://www.mandiesel...f12079/949e.pdf

Other diameters and L/d ratios used by various manufacturers may be utilized in the excel workbook.

I welcome comments on my blog entry from the knowledgeable members of the “Cheresources” community.

Quick note from the admin: You can download the MS Excel workbook that accompanies this blog entry in the File Library.

Regards,
Ankur.

Chexpress - June 25, 2014

Jun 25 2014 06:52 AM

North America

Polyethylene units

Chevron Phillips Chemical Company LP has had its second groundbreaking for its U.S. Gulf Coast Petrochemicals Project in Old Ocean, Texas. The construction includes two polyethylene units that will each produce 500,000 metric tons of plastic resin annually. The resin will be used for a variety of products, including new flexible packaging options that extend the shelf life of fruits and vegetables, as well as the creation of plastic piping, merchandise bags and bottles. In addition to constructing the production facilities, 45 miles of railroad track will be installed to hold and transport the output of these units.

HDPE plant

INEOS Olefins & Polymers USA and Sasol Chemicals North America LLC have reached a final investment decision to form a joint venture to build a high-density polyethylene (HDPE) plant in LaPorte, Texas. The 50/50 joint venture will produce 470 kilotons per year of bimodal HDP using technology licensed from INEOS Technologies. The ethylene required for the production of the HDPE will be supplied by INEOS and Sasol in proportion to their respective ownership positions. Plant start-up is expected in 2016.

Facility opens

Entegris Inc. has opened its new i2M Center for Advanced Materials Science in Bedford, Massachusetts. The $55 million facility will serve as the main innovation center for developing filtration and specialty coating technologies used to improve yields in microelectronics manufacturing environments.

World

Specialty esters plant

Oxea’s specialty esters plant in Nanjing, China is now complete and ready for commissioning and start-up. The plant will complement the company’s three existing specialty esters plants in Europe and will boost its global production capacity for specialty esters by 40 percent.

Fire

An explosion caused a fire at Caligen Europe’s plastics factory in Breda, The Netherlands. The flames were quickly extinguished and no one was hurt. The blast was in a machine used to make foam.

Oil refinery project

Two consortia from Russia and South Korea have emerged as the final bidders for Uganda’s $2.5 billion refinery after two others from China and Japan were knocked out of the bidding process. The Ministry of Energy said that a consortium led by South Korea’s SK Energy Co. and another led by Russia’s RT-Global Resources have been selected to proceed to the final phase of the bidding process. A bid from China Petroleum Pipeline Bureau did not adequately satisfy all the requirements of tender and a bid from Marubeni Corporation was not evaluated because it lacked a bid bond. The final winner is expected to take up a 60 percent stake in the project as well as develop and operate it. A final winner should be announced by the end of the fourth quarter this year. The facility is planned to process 60,000 bpd. Oil production is expected to begin in 2017 with maximum output expected to be 200,000 barrels.

Chexpress - June 11, 2014

Jun 11 2014 06:03 PM

North America

More time requested

The Environmental Protection Agency (EPA) has asked for more time to review a liquefied natural gas (LNG) export plant project planned for a site on a bay near Washington, D.C. The EPA requested the Federal Energy Regulatory Commission (FERC) grant a 30-day extension to conduct a review of Dominion Resources Inc’s Cove Point liquefaction project in Maryland. FERC had given the Cove Point project the green light last month and has not provided a comment on the extension request.

Acquisition

Phillips 66 is buying a 7.1 million-barrel storage terminal near Beaumont, Texas as part of the company’s plan to increase its logistics and transportation assets. The Chevron Corp. terminal is nearly 60 miles from Phillips’ nearest refinery. Phillips 66 has said the terminal will serve its own refineries as well as others in the U.S. The terminal has two marine docks capable of handling 750,000-barrel oil tankers, one barge dock, and rail and truck loading and unloading infrastructure. It has a storage capacity of 4.7 million barrels for crude and 2.4 million barrels for refined products. The sale is expected to close in the third quarter, pending regulatory approvals.

Acquisitions

Renewable Energy Group’s wholly owned subsidiary REG Synthetic Fuels, LLC has completed its acquisition of the remaining 50 percent ownership interest in Dynamic Fuels, LLC, which was previously owned by Tyson Foods. The new biodiesel facility will be known as REG Geismar, LLC and is a 75-million gallon renewable biorefinery in Geismar, Louisiana.

World

Fire

A fire at Royal Dutch Shell PLC’s plant in Moerdijk, The Netherlands has been extinguished. The cause of the explosion was not immediately clear. Two workers were treated for minor burns. The plant manufactures chemicals from petroleum that are used in products ranging from car components to synthetic fibers and insulation materials. Flames and large plumes of smoke could be seen from about 18 miles away.

Fire

Reliance Industries Ltd. had a minor fire break out at its poly butadiene rubber plant in Vadodara, India. The fire should not have any impact on production. No injuries were reported and the fire was brought under control by fire fighters at the plant. The cause of the fire is still under investigation.

Joint venture

Saudi Basic Industries Corp. (SABIC) has entered into a $595 million 50-50 joint venture agreement with SK Global Chemical to produce polyethylene products. The venture will operate a plant recently completed by SK in Ulsan, South Korea. The plant has an expected annual capacity of 230,000 tons. A second plant is planned for Saudi Arabia and the intent is to have production facilities established worldwide over time. The joint venture will be based in Singapore.

Technical Aspects Of Equipment Procurement

Jun 06 2014 02:55 PM

Dear All,
One of the readers of my blog made a suggestion about writing something related to equipment procurement. Well, I haven’t exactly acted as a procurement engineer in my career but fortunately did have the opportunity to interact with a few procurement engineers and pick up some ideas related to the methodology of equipment procurement.

One important thing to note about equipment procurement is that this activity is peculiar to the geographical location of the plant or unit. What it means is that equipment procurement has its own individual characteristics depending on whether this is being done in North America, European Union, Middle East, Africa, Asia-Pacific or South Asia.

I will not dwell on the logistics of equipment procurement since I have very little knowledge on the subject. However, I can certainly share some ideas related to the technical aspects of equipment procurement. Some of these ideas are shared point wise below:

1. Either the client (the knowledgeable ones) or the EPC contractor has an “Approved Vendor” list. The procurement engineer is bound by this vendor list and has no need to look further beyond this list for floating an enquiry. In fact, having an approved vendor list makes the procurement activity simpler.

2. Some companies have a registration process for being an approved vendor for the company. This may cause the “Approved Vendor” list to be too big with numerous vendors. Floating an enquiry for a particular equipment to all the vendors given in the “Approved Vendor” list for that equipment would not be a very practical thing to do. An experienced procurement engineer would probably trim the list of these vendors and restrict his enquiry to a top few vendors based on his knowledge of the vendor’s capabilities. Personally, I would restrict floating an enquiry to a maximum of four (4) vendors.

3. An experienced procurement engineer would ensure that the enquiries for the “long-lead” items are fast-tracked. A general definition of “Long-lead” items is an item that takes a longer time to procure. Various companies have their own norms on deciding what is meant by long-lead items depending on the type of plant that is being installed. As a rule-of thumb, I would consider any item with a lead time of more than 8 calendar months to be long-lead in today’s perspective of fast-tracked plants.

4. A good procurement engineer would keep continuous track of the response provided by the vendors in terms of submission of offers as per the enquiry. He or she would also be familiar with the process of raising “technical queries” often abbreviated as “TQ” on the offers provided by the vendors. In fact a procurement engineer who has an engineering design background prior to his taking up the responsibilities as a procurement engineer would be able to prepare a standard TQ format for various type of standard equipment. Having a standard TQ format saves time in the overall procurement cycle.

5. TQ’s may be raised by individual engineering disciplines in their own TQ formats. The procurement engineer will require collating all this information in one document for sake of clarity.

6. Most of the times information flows via e-mails with attachments and occasional telephonic conversation and video conferencing. I am a firm believer in a face-to-face communication with vendors. The resolution of unanswered questions and issues takes place best when you are sitting across the table and discussing. This has probably to do with human psychology. Some of the good procurement engineers I have interacted follow this very principle that I am advocating. Obviously, a good and meaningful way to have a discussion sitting across the table is to provide an advance discussion agenda to the party who you want to discuss with.

7. Once the offers from the vendors are streamlined to match the requirements of the project based on TQ resolution, the next step of “Technical Bid Analysis” abbreviated as “TBA” is conducted by the engineering design disciplines with active support and follow-up from the procurement engineer. Most good engineering companies have standard TBA formats for standard process plant equipment. The purpose of the TBA is to compare the offers of the vendors in the race for bagging the equipment order strictly from a technical view-point. The standard TBA worksheet has the benchmarking parameters of the particular equipment in the first column of the worksheet and the subsequent columns are information provided by the vendors against those benchmarked parameters. As an example, if you have 3 vendors there will be 3 columns in the worksheet for filling the data provided by the vendors against the benchmarked parameters. A summary section will be provided in the worksheet which will rate the vendors overall technical capabilities and provide rankings and in certain cases even a rejection of one or more of the vendors.

8. The next step would be the commercial negotiations for the equipment order. As an example, if three vendors have provided offers and the TBA concludes that all three of them are equal in their technical capabilities then by conventional logic it boils down to selecting a vendor offering the lowest first cost of the equipment. Please note, that this may not always be true and other factors such as market reputation of the vendor, past association with the company and other extraneous factors may take precedence in selection of the vendor.

9. The last step from a technical view-point in the procurement cycle would be placing the order of the equipment to the selected vendor in the form of a “Purchase Order" (PO) specification or requisition along with the commercial terms and conditions of purchase. The PO specification would generally include some technical data and information specific to the selected vendor's evaluated and accepted offer.

The aforementioned steps, however, do not end the procurement cycle or the responsibility of the procurement engineer. The logistics of equipment procurement now come into the forefront including items such as stage-wise inspection, factory acceptance test, test certification, packing, shipping, warehouse storage, insurance and demurrage. I will not deal with these items due to my inherent lack of knowledge on these matters. Maybe some experienced procurement engineer can provide some insight about the logistics part of the procurement process.

I look forward to a lot of comments from the readers of my blog.

Regards,
Ankur.

Chexpress - May 28, 2014

May 28 2014 06:36 AM

North America

Acquisition

Marathon Petroleum Corporation’s (MPC) subsidiary Speedway LLC has signed a definitive agreement with Hess Corporation to acquire Hess Retail Holdings LLC. This transaction includes all of Hess’ retail locations, transport operations and shipper history on various pipelines, including approximately 40,000 barrels/day on Colonial Pipeline. The $2,874 billion acquisition is anticipated to close late in the third quarter of 2014, subject to customary closing conditions and regulatory approvals. The acquisition will significantly expand MPC and Speedway’s retail presence from nine to 23 states.

Fine

Federal regulators have announced an $875,000 settlement with Chevron related to a pair of recent oil spills in Utah. The company has agreed on the settlement terms, resolving each of the federal penalties it faced in relation to the two spills. EPA officials say a June 2010 spill that dumped 33,000 gallons into Red Butte Creek and another 20,000-gallon leak near Willard Bay in 2013 violated the federal Clean Water Act.

Acquisitions

Terminix recently acquired assets of eight pest and wildlife control companies in 10 states. These acquisitions include Home Front Pest Control (Corona, Calif. area), R.P. Streiff Exterminating, Inc. (Tucson, Ariz.), Rove Pest Control (Bethel Heights, Ark.; Omaha, Neb.; Bixby, Okla.; and Nashville, Tenn.), Pioneer Wildlife Services, Inc. (Brooklyn, Conn. area), Generations Pest Control (Crestline, Calif.), Wild Animal Control (Plymouth, Mass.), Algee Termite & Pest Control, Inc. (Senatobia, Miss. area), and Ernie’s Pest Control, Inc. (Northwood, Ohio).

World

Leak

Samsung Total Petrochemicals Co Ltd had a small quantity of petrochemical product leak into the sea from a newly built paraxylene plant in South Korea. The company said the 2.4 kiloliters of para di ethyl benzene had been cleaned up. It leaked while flowing to test pipelines of the new plant. The new plant has an annual production capacity of 1 million tons of paraxylene and 420,000 tons of benzene.

Contract

Jacobs Engineering Group Inc. received a five-year frame agreement for work at three Borealis facilities in Belgium. The contract value was not disclosed. The three facilities covered under the contract are Borealis Polymers N.V., Borealis Kallo N.V. and Borealis Antwerpen Compounding N.V. Under the thres of the contract, Jacobs’ scope of work includes study, engineering, procurement, construction management, and personal support services on a variety of projects at the three facilities.

Maintenance

BP has closed part of its Tangguh liquefied natural gas (LNG) facility in West Papua, Indonesia for maintenance. The schedules repairs, which began on May 19, are expected to take 21 days to complete. The facility produces up to 7.6 million tons of LNG/year from its two existing liquefaction trains, supplying customers in Indonesia, South Korea, China, Japan and the United States. Work is underway to develop a third train at the facility, which BP expects to begin delivering gas in 2019.

Managing Technical Information Exchange With Process Equipment / Package Vendors

May 15 2014 06:42 AM

Dear All,

Today’s blog entry has shades of technical as well as communication skills. It is not restricted to process engineers and the guidelines provided in the subsequent paragraphs can be utilized by engineers from other disciplines such as Projects, Mechanical, Electrical, Instrumentation etc. in how to manage their dealings with manufacturers / vendors.

Before I begin, let us make a distinction between a manufacturer and vendor.

A manufacturer is the one who actually manufactures / fabricates and / or assembles the pieces of equipment for the particular end-use. A manufacturer need not necessarily assemble the pieces of equipment for end-use. This may be done by a third party who conforms to the assembly requirements of the equipment pieces as specified by the manufacturer. A common acronym which many experienced engineers are familiar with is “OEM” which expands to “Original Equipment Manufacturer”.

“Vendor” is a loosely used term and could mean a manufacturer, an assembler, a trader or the combination of all the three. Most experienced engineers in the process industry are more familiar with this term and I will be using this term rather than manufacturer.

Where does all this begin? It begins from the requirement of a particular equipment for a given chemical process plant and for a given chemical manufacturing process.

How does it appear as information in the first place? It gets represented in a “Process Flow Diagram” in the very first stage. The second stage involves qualifying the function of the equipment in terms such as exact type of equipment, capacity, power requirement (rotary equipment), material of construction, operating and design conditions (pressure / temperature), properties of the process material entering / leaving the equipment, compliance to statutory requirements (if any), HSE requirements and any special considerations.

The aforementioned information is generally captured as a “Process Datasheet” by the process engineer.

The third step would be to prepare a specification or material requisition which would provide further details for the requirement to be fulfilled. Some further information required to be part of a specification could be as follows:
- International / Company Standards that need to be followed in design and manufacture
- Vendor Documentation type and quantified in terms of number of paper / electronic documents
- Spares and consumables requirement in terms of commissioning and operation of the equipment
- Material testing and test certification requirement
- Inspection and testing of the completed equipment as per any established guidelines and standards.
- Packing and Shipping Instructions
- Site Conditions for equipment storage, erection and commissioning
- Erection / Commissioning / Operation / Maintenance instructions
- Lubrication Schedule

These are jus t a few to name. There could be many more depending on the type of equipment and specific project requirement.

Now let us discuss how to improve the communication with the vendor to expedite the procurement of the equipment as required or suited for the particular application and in a timely manner. Please note that the emphasis is on suitability of the equipment for a particular function and an adjective such as “best” has not been used to describe the equipment.

1. As far as possible avoid providing data as a wide range. Do your study to arrive at precise data and parameters for the equipment. There is practically no equipment which can perform well over a wide range. You are creating hurdles for the vendor to come up with a suitable equipment design by providing a very wide range of data. You should know the operating or rating case of your equipment.
2. Wherever possible please fill the information in the datasheet. Do a thorough analysis of what information you can provide and what you cannot. Ask vendor to provide only that information that is relevant for the equipment and is necessary for the selection of the equipment.

3. Asking for design information related to any proprietary design is a waste of time. It is better to prevail on the vendor to provide performance guarantees for a proprietary design. However, make sure by doing your homework that what the vendor is claiming to be a proprietary design, is really proprietary, and not something that is an open design.

4. Incomplete or incorrect information can be disastrous in terms of getting trapped in selecting the wrong equipment and allowing the vendor to escape from his contractual obligations for the performance guarantee of the equipment.

One of the most common examples of this would be the selection of a wastewater treatment plant. Incomplete or wrong chemical and biological analysis of the influent waste water would certainly lead to selection of the wrong treatment unit or units. This would be specifically true when the specifications of the discharged effluent from the treatment plant are very stringent and there are practically no margins on the discharged effluent quality as specified by regulatory authorities. It also gives the vendor the excuse of escaping from the performance guarantee clause of the contract by proving that the influent water quality is not correct or incomplete for his specific design. In a nutshell, wastewater analysis in terms of multiple samples over a spread of time would be the ideal way to ensure that the treatment plant selected gives the optimum performance in terms of quality of discharged effluent.

One major problem related to providing such data is how to manage this in case of a Grass-roots or Greenfield project. This is also manageable. Most reputed vendors maintain an extensive databank of projects they have executed in the past. It is very likely that they would have data related to a similar project executed in the past which could be used for your project. Here my emphasis is on reputed vendors with an extensive portfolio of executed projects.

5. Be prompt to raise queries to the vendor when you find an error in the vendor documents or something which does not fit into the scheme of your plant or unit. Remember the vendor is in the market to do business and earn a profit. You must understand your requirement precisely. Many times the vendor would try to sell you something extra which is not required for your application. The analogy goes like this:
“I only need a sedan. Why are you trying to sell me a limousine?”

I hope the above mentioned guidelines provide an insight to the new engineers on how to effectively communicate with vendors in order to ensure a proper and timely selection of any equipment or package.

I look forward to comments from the members of “Cheresources”.

Regards,
Ankur.

Chexpress - May 14, 2014

May 14 2014 09:55 AM

North America

Acquisition

Koch Agronomic Services, an affiliate of Koch Fertilizer LLC, which is a wholly owned subsidiary of Koch Ag & Energy Solutions LLC, plans to buy the Turf and Ornamental assets, brands and technologies of Agrium Advanced Technologies. Agrium Inc. is discontinuing operations of the Agrium Advanced Technologies business unit. The deal would mean a new production facility for Koch Agronomic Services in Sylacauga, Alabama. Deal terms were not disclosed, but it is expected to close at the end of the second quarter of 2014.

Acquisition

ShawCor Ltd. plans to acquired Desert NDT LLC in a deal valued at $260 million. The deal for Desert, which provides non-destructive testing services for new oil and gas gathering pipelines and infrastructure integrity management services, is expected to close in the third quarter, subject to regulatory approvals.

LNG production facility

North Dakota LNG, LLC, the newest member of Prairie Companies LLC’s portfolio of oil and gas businesses, will launch a new liquefied natural gas (LNG) production facility in Tioga, North Dakota. The plant will be the first-to-market in the state to produce 10,000 gallons/day starting in summer 2014. A phase two facility is scheduled to be operational in the fourth quarter of 2014 and capable of producing 66,000 gallons/day.

World

Financing received

Oman Oil Refineries and Petroleum Industries Company (Orpic) has received a $2.8 billion loan for projects, including the Sohar Refinery Improvement project (SRIP), which will be 65 percent debt financed. SRIP is a brownfield project and represents a significant technical improvement to the existing refinery, which will further enhance its capabilities to cope with changes in the quality of the Omani crude and reach international levels with environmental improvements, competitiveness and profitability.

Supply agreement

The Linde Group has signed an agreement to build a new hydrogen production unit for Neste Oil. Under the long-term on-site hydrogen supply agreement, Linde will build a new hydrogen production unit for Neste Oil’s Porvoo refinery near Helsinki, Finland. The project will be a total investment of about €100 million. Linde’s Engineering division will construct the turn-key plant. Linde’s North Eruopean subsidiary AGA will be responsible for the new unit’s operation, which is scheduled to come on stream in 2016 as part of the agreement.

Technology

UOP LLC’s technologies have been selected to produce key ingredients for fuels and synthetic rubber in China. China’s Lijin Petrochemical Plant Co., Ltd. will use Honeywell’s UOP C4 Oleflex process to produce isobutylene. Lijin Petrochemical will also use Honeywell’s UOP Butamer process, which converts normal butane into isobutene to increase feedstock flexibility for the UOP Oleflex process. The new unit is expected to start up in 2015 and produce 170,000 metric tons/year of isobutylene.

Chexpress - April 30, 2014

Apr 30 2014 07:11 PM

North America

Ethylene plant

Shintech Inc., the U.S. subsidiary of Shin-Etsu Chemical Co. Ltd., has applied for a permit to build a grassroots ethylene plant in Louisiana. The company intends to build the 500,000 tons/year capacity plant on industrial land that it already owns. Concurrently with this project, Shintech will continue its feasibility study on the amount to be invested for the proposed plant construction, the profitability of the project, and the amount of time that it will take for construction to be completed.

Pipe expansion

Williams Partners LP plans to expand part of its Transco pipeline to deliver natural gas to Cheniere Energy Partners LP’s Sabine liquefied natural gas (LNG) export facility under construction in Louisiana. Williams Partners said the project will cost about $300 million and it is planned to be in service in early 2017, subject to government approvals. Sabine is the only LNG export facility under construction in the U.S. and it is expected to be in service in late 2015.

Refinery upgrade

Marathon Petroleum Corporation is taking the next step toward a potential $2.2 billion to $2.5 billion upgrade to its Garyville, Louisiana refinery. The company plans to file permit applications with Louisiana’s Department of Environmental Quality at the end of April. It plans to complete feasibility studies to make a final decision on the project by early 2015. If approved, the project would result in hydrotreating, hydrocracking and desulfurization equipment installations, along with additional infrastructure, including buildings, tanks, cooling towers, and rail and electrical facilities.

World

Bids to lease storage

Petronet LNG has invited bids to lease storage at its Kochi regasification plant in Southern India due to a lack of pipelines connecting its key demand centers. Petronet is currently operating its 5 million tons/year Kochi plant at a fraction of its capacity as land-related issues have delayed the two pipelines that would link the terminal with customers in Bangalore and Mangalore. The Kochi terminal has two LNG storage tanks of nearly 182,000 cubic meters capacity each.

Petrochemical facilities

Iran plans to launch four new petrochemical plants in the current Iranian year calendar (which started March 21). The second phase of the Kavian Petrochemical Complex in Bushehr as well as the Lorestan, Kordestand and Mahabad complexes are scheduled to be operational by the end of the current Iranian calendar year.

Leak

An oil pipe leak caused excessive levels of benzene to arise in Lanzhou, China’s water supply. This prompted warnings against drinking from the tap and sending residents to buy bottled water. A crude oil pipeline run by China National Petroleum Corp. had a leak that tainted the source water feeding a local water plant.

Gas Boot Sizing Upstream Of Fwko Tanks

Apr 28 2014 12:34 AM

Gas Boots are provided upstream of a Crude Oil Dehydration tank in order to degass the crude oil before it enters the dehydration tank. Entrained gas in crude oil disturbs the settling process in a dehydration tank and it's removal is required to ensure quick and effective settling for separating bulk water in crude oil dehydration tanks also referred commonly as "Free Water Knockout" (FWKO) tanks.

It is important to note that Gas Boots are very effective up to a Gas-Oil-Ratio (GOR) of 10 Nm³/m³. Above the aforementioned GOR, a conventional gas-liquid separator is recommended.

In a gas boot the downward liquid velocity should not exceeed 0.1 m/s.

Gas boots are generally designed as a piece of piping in the inlet piping to the FWKO just uptream of the inlet connection to the FWKO. Today's blog entry provides a quick sizing method in terms of the diameter of the gas boot pipe and the wet and unstabilized crude oil nominal flow rate based on a reputed company guideline.

Refer the attachment for the sizing of gas boots.

Any comments are welcome.

Regards,
Ankur.

Chexpress - April 16, 2014

Apr 16 2014 06:29 AM

North America

Ethane cracker

Chevron Phillips Chemical Company LP has broken ground on its U.S. Gulf Coast Petrochemicals Project at its Cedar Bayou plant in Baytown, Texas. The project includes a 1.5 million metric tons/year ethane cracker in Baytown and two 500,000 metric tons/year capacity polypropylene facilities in Old Ocean, Texas. The estimated completion date for the project is in 2017.

New technologies

Statoil ASA is testing and aims to deploy up to 14 new technologies in the next five to ten years. The technologies are designed to reduce energy and water use when producing a barrel of bitumen from the company’s Canadian oil sands operations. The technologies have been included in plans for Statoil’s Comer Project in Alberta.

Agreement

The Linde Group has entered into an Enterprise Framework Agreement (EFA) with Shell Global Solutions International B.V. to build ethane cracking units globally. The EFA is for ten years with an option to be extended. The EFA covers the licensing, engineering, procurement and construction services, as well as the supply of proprietary equipment for ethane cracking units.

World

Investment

Petronas Chemicals Group Bhd and BASF Nederland BV have agreed to invest $462.82 million in an aroma ingredients complex in Pahang, Malaysia. The board of BASF Petronas Chemicals Sdn Bhd, a joint venture between BASF and Petronas Chemicals, approved the final investment decision. The first plant will come on stream in 2016.

Refinery and petrochemical project

Petroliam Nasional (Petronas) is proceeding with a $16 billion refinery and petrochemical integrated development called Rapid. Located in the Pengerang Integrated Complex in Johor, Malaysia, Rapid is scheduled to start refinery operations by early 2019. Other facilities in the complex will involve up to $11 billion of investment.

Contract

CB&I has been awarded a contract in excess of $40 million by Oman Oil Refineries and Petroleum Industries Company (Orpic) to provide ethylene technology and front end engineering and design (FEED) services for the Liva Plastics Project in Oman. CB&I’s scope includes FEED services for a 800,000 tons/year ethylene plant, pygas unit, MTBE and butane-1 unit, two polymer plants, a gas plant and pipeline, as well as the related off-sites and utilities.

Chexpress - April 2, 2014

Mar 31 2014 01:28 PM

North America

Expansion

3M is expanding its residential water business and will soon have hundreds of dealers selling 3M-branded water softeners and kitchen-sink filters to households around the United States. So far, 3M’s residential water division has contracted with 35 full-service dealers to spread the word about its products and compete with Culligan, Pentair and other water-filtration companies. The plan calls for 3M to brand its home equipment for the first time and for nearly 1,200 3M-labeled trucks to circulate neighborhoods by 2017.

Acquisition

Clean water startup NanoH20 is being acquired by LG Chem for $200 million. NanoH20 makes technology that can clean water, particularly seawater, with low amounts of energy. NanoH20 has developed nanotechnology-enabled reverse-osmosis membranes for desalinating water that are supposed to be more production and use less energy than traditional desalination membranes. NanoH20’s membranes are engineered to be more permeable than standard ones.

Split

FMC Corporation will split into two publically traded companies. The plan is to split the agricultural and nutrition segments off from the company’s industrial minerals divisions. The first company – “New FMC” – will consist of the Agricultural Solutions and Health and Nutrition segments, including EPAX, which FMC acquired for $345 million in 2013. In addition to EPAX omega-3s expertise, New FMC will also have considerable expertise in marine-soured ingredients. The second company – “FMC Minerals” – will consist of the company’s current industrial minerals segment. Both companies are expected to be listed on the New York Stock Exchange.

World

Expansion

Colombia’s 80,000 barrel-day single crude distillation unit at the Cartagena refinery has been stopped to undergo a planned expansion at the facility that will double its capacity by 2015. The cracking unit was previously stopped last year as part of the same expansion project, which will cost $6 billion. The effort is part of a broader push by Ecopetrol to lift refinery capacity to replace imports while also boosting exports.

Expansion

Petroperu will sign a contract in April to start work on a $3.5 billion refinery expansion with Tecnicas Reunidas. The project is aimed at increasing output at the Talara refinery by 50 percent to around 96,000 barrels/day. Boosting capacity at this facility is central to President Ollanta Humala’s goal of transforming Petroperu into a bigger regional energy player. Upgrades are scheduled to begin this year and end in 2017.

Contract

Petrovietnam Gas Corp., a subsidiary of Petrovietnam, has signed a contract to buy liquefied natural gas (LNG) from a Singapore-based subsidiary of Gazprom. No details on pricing or volume were released. Gazprom’s LNG will be delivered to PV Gas’ LNG terminal in Ba Ria-Vung Tau, which has an annual capacity of 1 million tons and will become operational in 2017.

Chexpress - March 19, 2014

Mar 19 2014 07:15 AM

North America

Expansion

Agrium Inc’s board of directors has approved an expansion of the company’s nitrogen facility in Borger, Texas. The $720 million project will add 610,000 tons of urea and 145,000 tons of ammonia production capacity. The expansion work will begin in March and is scheduled for completion in the second half of 2015. While expansion work is underway, the facility is expected to operate at its normal production rates.

Contract

CB&I was awarded a $100 million contract by CF Industries. As a result of the contract, CB&I will perform construction and component fabrication for CF Industries’ new urea ammonia nitrate and nitric acid units, offsites and utilities at its complex in Donaldsonville, Louisiana.

Acquisition

Intrexon Corporation has acquired laboratory operations in Budapest, Hungary from Codexis, Inc. The acquisition will expand Intrexon’s strain and protein development capabilities, enabling it to better service the European and Asian Markets. Intrexon’s Industrial Productions Division (IPD) will absorb the Budapest laboratory staff, integrating with Intrexon’s synthetic biology technologies and capabilities, allowing Intrexon to better serve current collaborations and attract new opportunities for active pharmaceutical ingredients (API) and industrial and consumer production collaborations.

World

Plants

ExxonMobil Chemical will build facilities to make a premium halobutyl rubber and Escorez hydrogenated hydrocarbon resin at its recently expanded petrochemical complex in Singapore. Engineering and procurement activities have started, with construction expected to begin in the second half of 2014. Completion is anticipated in 2017. This expansion will add 140,000 tons/year of halobutyl rubber production capacity.

Investment

S-Oil Corp will invest $7.49 billion to build heavy oil upgrading and petrochemical production units. S-Oil is expanding its heavy oil upgrading unit to raise gasoline production by nearly 50 percent up to 218.000 barrels/day. The company will build a 45,000 barrels/day atmospheric residue desulphurization unit and an up to 70,000 barrels/day residue fluid catalytic cracker (RFCC).

Fire

Lukoil’s petrochemical plant in Budyonnovsk, Russia experienced a fire recently. The fire wounded some. The fire broke out after a loss of pressure in the ethylene section of the plant. Company spokespeople declined to comment.

An Introduction To Corrosion Inhibitors

Mar 04 2014 03:35 PM

Dear All,

There have been quite a few threads devoted to injection of corrosion inhibiting chemicals on "Cheresources". Today's blog entry makes an attempt to give some introductory knowledge related to "Corrosion Inhibitors".

The following paragraphs provide the details. The reference for the content of this blog article is provided at the end of the blog article:

The use of chemical inhibitors to decrease the rate of corrosion processes is quite varied. In the oil extraction and processing industries, inhibitors have always been considered to be the first line of defense against corrosion. A great number of scientific studies have been devoted to the subject of corrosion inhibitors. However, most of what is known has grown from trial and error experiments, both in the laboratories and in the field. Rules, equations, and theories to guide inhibitor development or use are very limited. By definition, a corrosion inhibitor is a chemical substance that, when added in small concentration to an environment, effectively decreases the corrosion rate. The efficiency of an inhibitor can be expressed by a measure of this improvement:

Inhibitor Efficiency (%) = 100*(CR_uninhibited -CR_inhibited) / CR_uninhibited
where:
CR_uninhibited = corrosion rate of the uninhibited system
CR_inhibited = corrosion rate of the inhibited system

In general, the efficiency of an inhibitor increases with an increase in inhibitor concentration (e.g., a typically good inhibitor would give 95% inhibition at a concentration of 0.008% and 90% at a concentration of 0.004%). A synergism, or cooperation, is often present between different inhibitors and the environment being controlled, and mixtures are the usual choice in commercial formulations. The scientific and technical corrosion literature has descriptions and lists of numerous chemical compounds that exhibit inhibitive properties. Of these, only very few are actually used in practice. This is partly because the desirable properties of an inhibitor usually extend beyond those simply related to metal protection. Considerations of cost, toxicity, availability, and environmental friendliness are of considerable importance.

Attached Table presents some inhibitors that have been used with success in typical corrosive environments to protect the metallic elements of industrial systems. Commercial inhibitors are available under various trade names and labels that usually provide little or no information about their chemical composition. It is sometimes very difficult to distinguish between products from different sources because they may contain the same basic anti-corrosion agent. Commercial formulations generally consist of one or more inhibitor compounds with other additives such as surfactants, film enhancers, de-emulsifiers, oxygen scavengers, and so forth. The inhibitor solvent package used can be critical in respect to the solubility/dispersibility characteristics and hence the application and performance of the products.

Classification of Inhibitors
Inhibitors are chemicals that react with a metallic surface, or the environment this surface is exposed to, giving the surface a certain level of protection. Inhibitors often work by adsorbing themselves on the metallic surface, protecting the metallic surface by forming a film. Inhibitors are normally distributed from a solution or dispersion. Some are included in a protective coating formulation. Inhibitors slow corrosion processes by:

- Increasing the anodic or cathodic polarization behavior (Tafel slopes)
- Reducing the movement or diffusion of ions to the metallic surface
- Increasing the electrical resistance of the metallic surface

Inhibitors have been classified differently by various authors. Some authors prefer to group inhibitors by their chemical functionality, as follows:

Inorganic inhibitors: Usually crystalline salts such as sodium chromate, phosphate, or molybdate. Only the negative anions of these compounds are involved in reducing metal corrosion. When zinc is used instead of sodium, the zinc cation can add some beneficial effect. These zinc-added compounds are called mixed-charge inhibitors.

Organic anionic: Sodium sulfonates, phosphonates, or mercaptobenzotriazole (MBT) are used commonly in cooling waters and antifreeze solutions.

Organic cationic: In their concentrated forms, these are either liquids or waxlike solids. Their active portions are generally large aliphatic or aromatic compounds with positively charged amine groups.

However, by far the most popular organization scheme consists of regrouping corrosion inhibitors in a functionality scheme as follows:

Passivating (anodic)
Passivating inhibitors cause a large anodic shift of the corrosion potential, forcing the metallic surface into the passivation range. There are two types of passivating inhibitors: oxidizing anions, such as chromate, nitrite, and nitrate, that can passivate steel in the absence of oxygen and the non-oxidizing ions, such as phosphate, tungstate, and molybdate, that require the presence of oxygen to passivate steel.

These inhibitors are the most effective and consequently the most widely used. Chromate-based inhibitors are the least-expensive inhibitors and were used until recently in a variety of application (e.g., recirculation-cooling systems of internal combustion engines, rectifiers, refrigeration units, and cooling towers). Sodium chromate, typically in concentrations of 0.04 to 0.1%, was used for these applications. At higher temperatures or in fresh water with chloride concentrations above 10 ppm higher concentrations are required. If necessary, sodium hydroxide is added to adjust the pH to a range of 7.5 to 9.5. If the concentration of chromate falls below a concentration of 0.016%, corrosion will be accelerated. Therefore, it is essential that periodic colorimetric analysis be conducted to prevent this from occurring. In general, passivation inhibitors can actually cause pitting and accelerate corrosion when concentrations fall below minimum limits. For this reason it is essential that monitoring of the inhibitor concentration be performed.

Cathodic
Cathodic inhibitors either slow the cathodic reaction itself or selectively precipitate on cathodic areas to increase the surface impedance and limit the diffusion of reducible species to these areas. Cathodic inhibitors can provide inhibition by three different mechanisms: (1) as cathodic poisons, (2) as cathodic precipitates, and (3) as oxygen scavengers. Some cathodic inhibitors, such as compounds of arsenic and antimony, work by making the recombination and discharge of hydrogen more difficult. Other cathodic inhibitors, ions such as calcium, zinc, or magnesium, may be precipitated as oxides to form a protective layer on the metal. Oxygen scavengers help to inhibit corrosion by preventing the cathodic depolarization caused by oxygen. The most commonly used oxygen scavenger at ambient temperature is probably sodium sulfite (Na₂SO₃).

Organic
Both anodic and cathodic effects are sometimes observed in the presence of organic inhibitors, but as a general rule, organic inhibitors affect the entire surface of a corroding metal when present in sufficient concentration. Organic inhibitors, usually designated as film-forming, protect the metal by forming a hydrophobic film on the metal surface. Their effectiveness depends on the chemical composition, their molecular structure, and their affinities for the metal surface. Because film formation is an adsorption process, the temperature and pressure in the system are important factors. Organic inhibitors will be adsorbed according to the ionic charge of the inhibitor and the charge on the surface. Cationic inhibitors, such as amines, or anionic inhibitors, such as sulfonates, will be adsorbed preferentially depending on whether the metal is charged negatively or positively. The strength of the adsorption bond is the dominant factor for soluble organic inhibitors.

These materials build up a protective film of adsorbed molecules on the metal surface, which provides a barrier to the dissolution of the metal in the electrolyte. Because the metal surface covered is proportional to the inhibitor concentrates, the concentration of the inhibitor in the medium is critical. For any specific inhibitor in any given medium there is an optimal concentration. For example, a concentration of 0.05% sodium benzoate or 0.2% sodium cinnamate is effective in water with a pH of 7.5 and containing either 17 ppm sodium chloride or 0.5% by weight of ethyl octanol. The corrosion due to ethylene glycol cooling water systems can be controlled by the use of ethanolamine as an inhibitor.

Precipitation inhibitors
Precipitation-inducing inhibitors are film-forming compounds that have a general action over the metal surface, blocking both anodic and cathodic sites indirectly. Precipitation inhibitors are compounds that cause the formation of precipitates on the surface of the metal, thereby providing a protective film. Hard water that is high in calcium and magnesium is less corrosive than soft water because of the tendency of the salts in the hard water to precipitate on the surface of the metal and form a protective film.

The most common inhibitors of this category are the silicates and the phosphates. Sodium silicate, for example, is used in many domestic water softeners to prevent the occurrence of rust water. In aerated hot water systems, sodium silicate protects steel, copper, and brass. However, protection is not always reliable and depends heavily on pH and a saturation index that depends on water composition and temperature. Phosphates also require oxygen for effective inhibition. Silicates and phosphates do not afford the degree of protection provided by chromates and nitrites; however, they are very useful in situations where nontoxic additives are required.

Volatile corrosion inhibitors
Volatile corrosion inhibitors (VCIs), also called vapor phase inhibitors (VPIs), are compounds transported in a closed environment to the site of corrosion by volatilization from a source. In boilers, volatile basic compounds, such as morpholine or hydrazine, are transported with steam to prevent corrosion in condenser tubes by neutralizing acidic carbon dioxide or by shifting surface pH toward less acidic and corrosive values. In closed vapor spaces, such as shipping containers, volatile solids such as salts of dicyclohexylamine, cyclohexylamine, and hexamethylene-amine are used. On contact with the metal surface, the vapor of these salts condenses and is hydrolyzed by any moisture to liberate protective ions. It is desirable, for an efficient VCI, to provide inhibition rapidly and to last for long periods. Both qualities depend on the volatility of these compounds, fast action wanting high volatility, whereas enduring protection requires low volatility.

I would enjoy having a discussion and some insight on "corrosion inhibitors" from knowledgeable members of the forum.

Reference: Chapter 10, Corrosion Inhibitors" "Handbook of Corrosion Engineering" by Pierre R. Roberge

Regards,
Ankur

Chexpress - February 19, 2014

Feb 19 2014 08:42 AM

North America

Ethane

INEOS Europe AG has announced a new ethane purchase agreement with CONSOL Energy in the USA. Ethane will be transported through the Mariner East infrastructure and imported by sea for use in INEOS’ European cracker complexes. Supplies will start in 2015.

Thermal Plant

The Ivanpah Solar Electric Generating System sprawls across roughly 5 square miles of federal land near the California-Nevada border. The $2.2 billion complex of three generating units is owned by NRG Energy Inc., Google Inc. and BrightSource Energy. It can produce nearly 400 megawatts of power.

Purchase

Phillips 66 Partners LP will buy a 681-mile refined products pipeline system and two refinery-grade propylene storage systems from Phillips 66 for $700 million. Phillips 66 Partners will now operate the 132,000 barrels/day Gold Line System that runs from a Phillips 66-operated refinery in Borger, Texas to Cahokia, Illinois. The storage systems in Medford, Oklahoma have a total working capacity of 70,000 barrels and are scheduled to start operating on March 1.

World

Postponement

Peru has pushed back the date it will announce the winner of the rights to build a $2.5 billion natural gas pipeline. The date has been pushed from Feb. 17 to June 30. The concession date has been changed twice since initially being scheduled for Oct. 7 of last year.

Refinery

PetroChina’s newly started $6 billion greenfield and petrochemical complex in Pengzhou is expected to start commercial operations by early April. The PetroChina plant is designed to process Kazakh, Russian oil as well as PetroChina’s own crude from the Xinjiang region. Crude will be piped from neighboring Kazakhstan via a trunk pipeline started in 2006. The refinery is integrated with a petrochemical complex, including an 800,000 ton/year ethylene unit, which makes feedstock for plastics and textiles.

Cracking Furnace Project

Technip was awarded a contract by Open Joint Stock Company to provide technology and services for a grassroots furnace at Kazan, Russia. The project consists of the engineering and procurement of an SMK double-cell cracking furnace. The project follows the successful start-up and operations of a Technip SMK double-cell cracking furnace supplied in 2007. The furnaces are part of the ethylene plant at the seat, with the output used as feedstock for other downstream units. Technip’s operating center in Zoetermeer, The Netherlands will execute the project, which is scheduled for mechanical completion in 2015.

Software Upgrade

ProSim has released a new version of its Simulis Thermodynamics software. This new version is compatible with 64-bit applications for thermodynamic calculations. Simulis Thermodynamics 2.0 also includes a pure-compound physical properties prediction tool for molecules.

Chexpress - February 5, 2014

Feb 04 2014 07:23 PM

North America

Acquisition

Gerdau Ameristeel has entered into an agreement with Ameron International, Tokyo Steel and Mitsui & Co. to acquire all the issued and oustandig shares of TAMCO. TAMCO is a mini-mill steel producer of reinforcing steel bar and is one of the largest rebar mills in the western U.S. with an annual capacity of approximately 500,000 tons. The purchase price is approximately $165 million in cash and the deal is expected to close this quarter. With its divestiture of 50 percent of TAMCO, Ameron International will focus on its core pipe systems business involved in the transmission of water and corrosive fluids and gases.

Research

Monsanto Co. is opening a wheat-breeding research center in Great Falls, Montana. The company is offering assurances that the facility will involve conventional research and not genetically modified organisms. The aim of the research will be to come up with better varieties that product better yield and products. Seed varieties will be developed at the company’s Wheat Technology Center in Twin Falls, Idaho, by cross-breeding different types of seeds. The resulting seeds will be grown in test plots north of Great Falls to study how well the varieties grow in various soils and environments to assess if they are commercially viable.

Stake

Hedge fund Third Point LLC has acquired a significant stake in Dow Chemical and wants the company to spin off its petrochemicals division. Third Point says Dow is now its biggest investment, but didn’t specify how many shares it had acquired other than to say it was a significant position.

World

Bids

The Organization for the Prohibition of Chemical Weapons (OPCW) says 14 private sector companies submitted bids to destroy chemicals removed from Syria as part of international efforts to dismantle Damascus’ poison gas and nerve agent program. The companies were from a number of countries including the United States, Britain, Russia, China and Saudi Arabia. The companies submitted tenders to destroy 500 metric tons of chemicals and waste material resulting from the destruction of other Syrian chemicals. The chemicals to be destroyed by the private companies are regularly used in the pharmaceutical and other industries and can be safely disposed of at civilian facilities. The OPCW is conducting technical and commercial evaluations of the bids before announcing which companies will be awarded contracts.

Stake

Repsol has agreed to sell its 10 percent stake in the Transporta dora de Gas del Peru gas pipeline in to Engas SA for $219 million. The deal will be completed in the coming months. TGP transports natural gas and liquids from Camisea fields inland to the Peru LNG liquefaction plant in Pampa Melchorita.

Overcapacity

PetroChina has put off starting up two new refineries and delayed expansion of another to counter the threat of overcapacity as oil demand growth slows in China. China’s oil consumption last year grew at its slowest in more than 20 years as soft economic growth sliced demand for transportation and industrial fuels such as diesel. The company will now start up its 200,000 barrels/day Kunming refinery in the Yunnan province in 2016, two years behind the original schedule. Operation of a 400,000 barrels/day joint venture refinery in Jieyang of Guangdong province will be delayed to 2017 versus the original plan of 2013. The company will also delay expansion of its Huabei refinery in north China to 2015 from this year.

Ultra-low Sulfur

Exxon Mobil Corp’s new hydrotreater has started operations and is producing ultra-low sulfur diesel at the company’s 592,000 barrels/day Singapore refinery. The new unit will increase the facility’s daily low-sulfur diesel capacity to 25 million liters or about 157,000 barrels. About 36 percent of that, or 57,000 barrels/day, will meet ultra-low sulfur diesel specifications. With the new unit, the refinery is able to product both 50 and 10 parts per million low sulfur diesel.

Uklpg (British) Code Of Practice For Safety In Bulk Lpg Storage

Feb 04 2014 02:29 AM

Dear All,

LPG storage and the related safety considerations have been discussed many times on various threads on 'Cheresources'. Any reader / member of 'Cheresources' can find these threads using the search facility on 'Cheresources'.

Today's blog entry presents the British perspective on safety related to bulk LPG storage. The reference for this blog entry has been provided at the end of this blog entry. Let us understand what the British view on safe LPG bulk storage means:

Safe storage and handling of LPG is of paramount importance, whether it is in bulk or in cylinders. This is basically achieved by ensuring the mechanical integrity of the storage vessels or cylinders and by strict observance of the recommended separation distances between storage and buildings or boundaries. This passive protection has to be supplemented by rigorous observance of operational procedures. The Liquefied Petroleum Gas Association (LPGA) has issued a Code of Practice on bulk LPG storage at fixed installations in collaboration with and approval of the Health and Safety Executive. Part 1 deals with design, installation and operation of vessels above ground.

Note: UKLPG was formed by the merger of the LP Gas Association (LPGA) and the Association for Liquid Gas Equipment and Distributors (ALGED) in January 2008. Its roots are firmly established, with LPGA and ALGED established in 1947 and 1975 respectively.

Perhaps the most serious hazard to LPG storage is that of accidental fire. The safety distances are intended to separate the storage from possible adjacent fires so that the risk of a fire affecting the storage is very low. However, this residual risk has to be catered for. The mechanical integrity needs to be assured under severe fire attack. For this reason, the vessels are provided with relief valves designed to cope with fire engulfment. The heat from such a fire may raise the stored pressure until the relief valve opens. The discharge capacity of the relief valve when fully open is required to meet or exceed the following:

Q = 10.6552*A^0.82

where:
Q = Relief Valve capacity in m³/min of air @15°C, 1.01325 bar (abs)
A = total surface area of the vessel, m²

The heat transfer to the liquid from an engulfment fire has been estimated at around 100 kW/m², and the above formula equates this to the vapor produced from this input as latent heat. The exponential is an area exposure factor which recognizes that large vessels are less likely to be completely exposed to flames.

The safety relief valve will protect the liquid-wetted areas of the storage vessel. The metal temperature will not significantly exceed the liquid temperature which will be absorbing the latent heat of vaporization. However, above the liquid line no such cooling will take place. The metal temperature at the top of the vessel could therefore exceed safe limits.

The usual protection for large installations is to provide a water-spray system. For small bulk storage, fire hoses or monitors are often adequate. However, for installations over 50 tons of storage (and all major cylinder-filling plants) it is accepted that a fixed water-spray system needs to be provided which is automatically initiated by a system capable of detecting a fire threatening the vessels and/or the adjacent tanker loading or unloading area. The deluge rate to provide protection against fire engulfment is 9.8 liter/min/m² of vessel surface area, and this should be capable of being sustained for at least 60 minutes. The spray pattern adopted for a fixed installation normally includes four longitudinal spray bars, two at the upper quadrants and two at the lower quadrants of horizontal cylindrical vessels, with nozzles spaced to give uniform coverage.

An alternative means of avoiding the hazard from fire is to bury the vessels or to employ the increasingly popular method of mounding. In either case acknowledgment of the reduced hazard is indicated by the reduced separation distances (see attached table). Since either burial or mounding preclude the possibility to monitor continuously the external condition of the vessels, very high-quality corrosion protection needs to be applied, normally supplemented by cathodic protection, depending on soil conditions. Guidance approved by the H.S.E. is published by the LPGA in their Code of Practice 1 part 4.

The use of burial or mounding is sometimes employed to overcome visual environmental objections since the mounding, for instance, can be grassed over. Indeed, this is the method often adopted to prevent erosion of the mounding material.

Hope all of you have enjoyed this small article related to safety on Bulk LPG storage as followed in the UK.
I do expect some comments and will be glad to share my views on the comments.

Regards,
Ankur

Reference: Chapter 14, Plant Engineer's Reference Book , 2^nd Edition by Dennis A. Snow

Attached thumbnail(s)

Design Equations For Venturi Scrubbers

Jan 26 2014 11:42 PM

Dear All,

Many of you involved in engineering and design of wet scrubbing systems are already familiar with “Venturi Scrubbers”.

Venturi Scrubbers are primarily designed to control fine particulate matter (PM) from gaseous streams. Before releasing waste gases that contain PM to the atmosphere, these gases are treated using venturi scrubbers to remove PM. Generally the effective range of PM removal is from 10 microns to 2.5 microns. They are also capable of some incidental control of “Volatile Organic Compounds”, which, however is not their primary function. They can also be used for capturing high solubility gases which have good solubility with the sprayed liquid.

Venturi scrubbers have high efficiencies when capturing PM in the range of 0.5-5 micron.

Venturi scrubbers have following typical industrial applications:
a. Boiler waste gases utilizing coal, oil, biomass and liquid waste
b. Metal Processing – Iron & Steel, Aluminum
c. Wood, Pulp & Paper Industry
d. Chemical Industries
e. Municipal Solid Waste Incinerators

For a detailed description on venturi scrubbers refer the Wikipedia link below:
http://en.wikipedia....enturi_scrubber

Today’s blog entry relates to some design equations for evaluating liquid droplet diameter, collection efficiency, throat velocity, throat diameter, throat length and pressure drop for venturi scrubbers:

Liquid Mean Droplet Size or Sauter Mean Diameter

Nukiyama & Tanasawa Correlation

d_l = (0.000585/v_r)*sqrt(σ/ρ_l) + 0.0597*(µ_l /sqrt(σ/ρ_l))^0.45*(Q_l/Q_g)^1.5
where:
d_l = mean droplet diameter, m
v_r = relative velocity of gas to liquid, m/s = v_g –v_l ≈v_g
Note: In most cases, the gas velocity is much higher than the liquid velocity and v_r may be considered equal to v_g
σ = liquid surface tension, N/m
ρ_l = liquid density, kg/m³
µ_l = liquid viscosity, Pa.s
Q_l = volumetric flow rate of liquid, m³/s
Q_g = volumetric flow rate of liquid, m³/s

Boll et. al Correlation

d_l = (0.042 +0.00565*(1000*Q_l / Q_g)) / v_r^1.602

Collection Efficiency

η = 1 – e^(-k*R*sqrt(ψ))----(1)
where:
η = collection efficiency of the venture scrubber, fraction
k = correlation coefficient whose value depends on system geometry and operating conditions (typically 0.1-0.2)
R = liquid-to-gas ratio, m³/1000 m³
ψ = inertial impaction parameter, dimensionless
Note: R values between 0.936 m³/1000 m³ and 1.337 m³/1000 m³ provide optimum collection efficiency
ψ = C*d_p^2*ρ_p*v_t / (9*µ_g*d_l)-----(2)

where:
C = Cunningham Slip correction factor, dimensionless

C = 1 + (0.000621*Tg / (d_p*10^6))-----(3)
T_g = inlet gas absolute temperature, K
d_p = particle diameter, m
ρ_p = particle density, kg/m³
v_t = throat velocity, m/s
µ_g = gas viscosity, Pa.s
d_l = liquid mean droplet diameter, m

Normally collection efficiency is an input, so re-writing equation (1) in terms of ψ:
ψ = (ln(1-η) /(k*R))^2-----(4)

Since we want to know the throat velocity, re-writing equation (2) in terms of v_t:
v_t = ψ*9*µ_g*d_l / (C*d_p^2*ρ_p)-----(5)

Throat Length

l_t = 369.561*R^0.293 / v_t^1.127
where:
l_t = throat length, m
R = liquid-to-gas ratio in L/m³ (to convert m³/1000 m³ to L/m³ multiply m³/1000 m³ with 0.001)
v_t = throat velocity, m/s

Throat Area

A_t = Q_g / v_t
where:
A_t = throat area, m²
Q_g = process gas flow rate, m³/s
v_t = throat velocity, m/s

Pressure Drop in Venturi Scrubbers (Hesketh Equation)

ΔP = 0.532*v_t^2*ρ_g*A_t^0.133*(0.56 + 16.6*(Q_l/Q_g) + 40.7*(Q_l/Q_g)^2)
where:
ΔP = Pressure drop, Pa
v_t = throat velocity, m/s
ρ_g = gas density downstream of throat, kg/m³
A_t = throat area, m²
Q_l = volumetric flow rate of liquid, m³/s
Q_g = volumetric flow rate of gas, m³/s

Hope the readers of this blog entry have now some idea about the design equations related to venturi scrubbers. Please note that the liquid-to-gas ratios are basically ratios and any set of volumetric flow rate units may be used as long as they are consistent for both liquid and gas.

The entire blog entry has been a compilation from various resources related to Venturi scrubbers. However the following resources can be referenced from the links provided below:

http://web2.clarkson... Dev_120408.pdf

http://tean.teikoz.g...ations/12_3.pdf

http://books.google....bber Pa&f=false

I will try my best to provide answers to any questions raised. All these equations are programmable in an excel spreadsheet.

Regards,
Ankur.

Chexpress - January 22, 2014

Jan 22 2014 06:53 PM

North America

Facility opening

Air Products and Chemicals, Inc. has opened a new manufacturing facility in Manatee County, Florida. The facility has created 250 new jobs and is injecting $56.8 million of capital investment into the community. The new facility will be used to manufacture large custom-made chemical process equipment for overseas customers. Air Products will benefit from this location and its close proximity to Port Manatee.

Acquisition

International Flavors & Fragrances (IFF) has acquired Aromor. Terms of the deal were not disclosed, but analysts estimate that the company was sold for $88 million. Aromor was privately held, half-owned by Kibbutz Givat Oz in the Lower Galilee, Israel. Most of Aromor’s products are kosher and most are exported to Europe, Asia, North America and Latin America. The company’s factory will remain at its present location and all of the company’s 85 employees are expected to remain on the job. Prior to the acquisition, Aromor was a supplier to IFF.

Plant revamp

Pemex will spend up to $475 million to buy and revamp a fertilizer production plant in Cosoleacaque, Veracruz, Mexico. This investment will allow the company to produce up to 990,000 tons of urea annually. The deal between Pemex subsidiary PMI and Minera del Norte subsidiary Agro Nitrogenados would allow the company to supply 75 percent of Mexico’s demand for urea. Pemex plans to replace more than $400 million worth of annual imports of urea, which is widely used in fertilizer as a source of nitrogen. Ammonia, a main input in fertilizer production, will be supplied by Pemex’s petrochemical complex located 28 kilometers from the Agro Nitrogenados plant.

Air permit

South Louisiana Methanol LP (SLM) has received the required air permit from the LDEQ and the State of Louisiana to construct and operate its methanol facility in St. James Parish, Louisiana. With the air permit now in place, SLM is on track to begin construction during the second half of 2014, with facility commissioning projected for January 2017.

World

Job cuts

Sasol Ltd. may cut as many as 1,000 jobs as the company prepares for a reorganization. The company employs more than 35,000 people in 37 countries. Talks with the union started in late November after Sasol and Bain & Co. developed proposals to reduce the company’s size. Sasol plans to save $279 million from cost cuts within the next two to three years. The company anticipates that for at least the next six months, the impacts will be limited to senior management.

Takeover offer

Bayer’s planned acquisition of Algeta ASA has entered its next phase. Aviator Acquisition AS, a subsidiary established by Bayer Nordic SE, Espoo, Finland, commenced a public takeover offer for all the shares of Algeta at the price of NOK 362/share in cash. The total value of the transaction is approximately NOK 17.6 billion (EUR 2.1 billion). Bayer issued the takeover offer on the basis of a transaction agreement signed with Algeta on Dec. 19, 2103. Algeta’s Board of Directors unanimously recommended that its shareholders accept the offer. The completion of the offer is subject to customary closing conditions.

Expansion

Formosa Plastics Group will invest $13.25 billion in overseas expansion this year. This is the Taiwanese company’s biggest annual capital budget in five years. The group plans to expand in China and Vietnam as well as build a petrochemical project in Texas.

Biofuels

Boeing Co., Etihad Airways, Total, Takreer (a subsidiary of Abu Dhabi National Oil Co.) and the Masdar Institute of Science and Technology say they will work together on a program to develop an aviation biofuel industry in the United Arab Emirates. The program will involve research and development and investments in production of fuels derived from plants that can power aircraft.

Chexpress - January 8, 2014

Jan 08 2014 07:26 AM

North America

Purchase

Ergon Inc. has purchased Bunge North America Inc’s stake in the Ergon Biofuels plant in Vicksburg, Mississippi. Ergon purchased Bunge’s share of what had been a 2007 joint venture of a 54 million gallon/year ethanol plant, the only facility that produced corn-based ethanol in the state. Financial terms were not disclosed. A company spokesperson said the transaction allows them to look at alternative feedstocks as well as how the plant may be used for other products.

Acquisition

Ergon-Texas Pipeline, Inc. has acquired the Thompsons pipeline and associated assets from Blueknight Energy Partners, LP. The 42-mile pipeline originates in Thompsons, Texas and terminates in Webster, Texas. Terms of the agreement were not disclosed.

Ethylene Cracker

Axiall has selected the state of Louisiana as the location of a possible ethylene cracker to be built in conjunction with a related derivatives plant. The company is proposing to construct the facility with a to-be-named partner. The company anticipates it will make a $1 billion capital investment for the project. Axiall is set to begin the permitting process and certain front-end engineering design activities as the next steps to select a final site for the project. If the project moves forward, commercial operation could begin in 2018.

Chlor-Alkali Plant

Westlake Chemical Corporation has started up its new chlor-alkali plant at its vinyls manufacturing complex in Geismar, Louisiana. The plant has the capacity to produce 350,000 electrochemical units (ECUs) annually and uses state-of-the-art membrane technology. The plant is adjacent to the complex’s existing vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) facilities.

World

Coal-to-Chemical Plant

Sinopec Engineering Group has entered into an agreement to build a $3.1 billion plant in northern China to turn coal into petrochemicals. Sinopec Engineering will be responsible for the engineering, procurement and construction of the plant. The plant would produce 3.6 million tons/year of olefins, mostly ethylene. Key facilities of the investment include a 3.6 million tons/year synthetic methanol unit, two 1.8 million tons/year methanol to olefin units and two polypropylene units. Sinopec Engineering will hand over the project to Zhong Tian He Chuang Co. Ltd., a joint venture which has Sinopec Corp. and China Coal Energy Company among its main investors, by Oct. 30, 2015.

Phosphate Project

Saudi Arabian Mining Company (Ma’aden) has commitments from banks for financing worth up to $4.2 billion for a $7 billion phosphate project in Saudi Arabia. The project in Waad-al-Shimal is a joint venture between Ma’aden, Saudi Basic Industries Corp. and Mosaic. It is part of the Saudi state efforts to create a stronger industrial base beyond oil refining and export. The rest of the funding should come from the Public Investment Fund (PIF) and Saudi Industrial Development Fund (SIDF) as well as some export credit agencies (ECA). The project will have a production capacity of 16 million tons/year of phosphate concentrate, sulphuric acid, phosphoric acid, as well as plants to produce calcium monophosphate and calcium diphosphate. Phosphate production is expected to start in late 2016.

Stake Purchased

EPH has bought E.ON’s 40 percent stake in gas storage company Nafta. SPP is Nafta’s main shareholder with a 56 percent stake. EPH also holds a 49 percent share in SPP. Nafta has natural gas storage capacity of 2.3 billion cubic meters.

Hyperfocal Distance Calculator

Jan 07 2014 07:18 AM

Dear All,

This blog entry is not related to chemical engineering but it certainly is related to the science of optics and should provide interesting reading for those chemical engineers who happen to be photography enthusiasts and want to know some intricacies related to the science of photography

I have always loved photography right from the days when I bought my first Konica Minolta film camera in 1987. However, for reasons unknown I was not able to pursue this hobby of mine in a serious manner. Recently, I rediscovered my lost passion for photography and have now started seriously pursuing it. To regain my lost touch I started reading quite a lot of material on photography and found some really interesting and enlightening reading material as a photography enthusiast.

It is quite possible that a lot many of the chemical engineers who are members and readers of "Cheresources" may be serious enthusiasts of photography and spend some of their spare time pursuing photography.

Let me also explain the difference between a casual photographer and an enthusiast photographer. A casual photographer uses the "Automatic" mode on his digital camera to click pictures and leaves it at that. An enthusiast photographer uses or tries to use the "semi-automatic" and "manual" modes on his camera to click pictures where his understanding and judgement of how he is clicking a particular scene or person comes into play. In a nutshell, an enthusiast photographer is concerned about the quality and the ability to draw serious attention to the picture he has clicked.

I love landscape photography and try to do it whenever I can go on a holiday to a tourist destination.

Optics in itself is a vast subject of physics. Modern digital cameras have evolved so much that today you can take pictures of stunning beauty and clarity with just a click of the shutter button. However, till date no amount of advancement in the science of optics has been able to mimic the functions of the human eye and its coordination with the brain.

I don't have the luxury to indulge myself in a detailed discourse on photography and optics. Suffice to say that those who have some knowledge of photography and specifically landscape photography will be able to grasp what I am trying to explain.

When you do any kind of photography you have to focus on an object in your camera viewfinder or LCD screen. The area in front of the object of focus is called as 'foreground' and the area behind the object of focus is called 'background'. Most of the times when an object is focused on the camera and a picture is taken either the foreground or background do not come out sharp in the picture. The objective of producing a good landscape photograph is to have everything in the frame to be sharp and not blurred, the exception being portrait photography.

Then hyperfocal distance determines how sharp your landscape photograph will be, if you focus your camera at a pre-designated distance from the camera lens.

In technical terms hyperfocal distance is defined as follows:

The hyperfocal distance is the closest distance at which a camera lens can be focused while keeping objects at infinity acceptably sharp. When the camera lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.
http://en.wikipedia....rfocal_distance

How to calculate the hyperfocal distance? If you know or set the focal length of the lens of your camera and the aperture setting in say aperture priority or manual mode when you want to click the picture you can calculate the distance at which you should focus to get a very sharp landscape picture with both the foreground and the background being sharp.

The attachment with this blog entry calculates the hyperfocal distance for various digital camera brands based on a camera specific attribute called 'Circle of Confusion'.

Hoping to get comments from chemical engineers who are also photography enthusiasts.

Regards,
Ankur

Attached File(s)

Hyperfocal Distance Calculator.xlsx (9.47MB)
Number of downloads: 890

Time Dependent Gas Release Through A Hole From A Pressurized Container

Dec 23 2013 01:37 PM

Dear All,

One of the very important books related to process safety is popularly known as the "Yellow Book" published from the Netherlands and having the full title as:

"Methods for the calculation of physical effects - due to releases of hazardous materials (liquids and gases)" - 'Yellow Book' - CPR14E

The best part of this book is that it is absolutely free to download from the internet. The units used in the book are purely SI units which might prove somewhat of a dampener fro those quite used to engineering units and English units. In its treatment of the physical phenomena of gaseous and liquid releases it is an absolute delight to read. The coverage is extensive and wherever possible numerical methods to enunciate the physics involved in releases is provided.

It also encompasses other safety related topics such as vapor cloud dispersion, vapor cloud explosion, heat flux from fires etc.

Below a link is provided for a free download of the book:

http://content.publi...cal-effects.pdf

The title of my blog entry does not suggest anything about the book but I wanted to make it clear that the topic I have chosen i.e. 'Time Dependent Gas Release through a hole from a pressurized container' is basically picked up from the 'Yellow Book'.

I have prepared a spreadsheet based on the theory and equations provided in the 'Yellow Book' for the subject with an example. A few relevant pages of the 'Yellow Book' with certain sections highlighted have also been provided in the spreadsheet.

Those process engineers who have access to HYSYS or any other similar process simulation software where vessel depressurization dynamic utility is available, may find that the results are not closely matching with the spreadsheet that has been presented along with this blog entry. The reason is that a few simplified assumptions have been done which the book also follows to arrive at the results. Some of these are as follows:
1. The process of the vessel depressurization is considered to be an adiabatic process only.
2. The specific heat or heat capacity at constant volume (C_v) is considered to be constant along the depressurization path although the dynamic change in pressure and temperature during the depressurization will have some effect on the specific heat value. In other words, there will be minor changes in the specific heat value at different dynamic values of pressure and temperature.
3. The specific heat ratio (C_p/C_v) is also considered to be constant along the depressurization path based on the same premise presented above in point number 2.

Again the idea of presenting a spreadsheet is to ensure that those process engineers who do not have access to expensive simulation software are not left out.

Hope all of you enjoy this blog post and the accompanying spreadsheet. I look forward to your comments and definitely look forward to comparisons of the example given in the spreadsheet with the results obtained form a "Dynamic Depressuring Utility" from a simulation software such as HYSYS or similar.

Regards,
Ankur.

Quick note from the admin:
Download the MS Excel sheet here:
http://www.cheresour...through-a-hole/

Chexpress - December 10, 2013

Dec 11 2013 12:32 AM

North America

Sale

Carlyle Group LP is preparing an initial public offering or sale of PQ Corp that could value the specialty chemical company at up to $3 billion, including debt. The private equity firm, which bought PQ for $1.5 billion in 2007, plans to talk to investment banks to choose underwriters for the proposed offering. Carlyle will also explore a sale of PQ to another firm.

Contract won

CB&I has been awarded a contract valued at approximately $1 billion by Ingleside Ethylene LLC, a joint venture between Occidental Chemical Corporation (OxyChem) and Mexichem S.A.B. de C.V., for the engineering, procurement and construction of an ethane cracker and associated utilities and offsites to be located at OxyChem’s complex in Ingleside, Texas. The cracker will have the capacity to produce approximately 1.2 billion pounds/year of ethylene from a feedstock that is anticipated to be ethane derived from domestic shale gas. CB&I had previously provided the technology license and basic engineering for the ethylene technology, five short residence time (SRT) cracking heaters and the front end engineering and design (FEED) services.

Sale

Dow Chemical Co. will sell a bulk of its chlorine operations – its oldest business – as part of its plan to sell or spin off commodity chemicals assets worth up to $4 billion. Company representatives say this will allow the company to prioritize its capital on higher margin, more consistent earnings growth businesses. Other assets identified for sale by Dow Chemical include the company’s epoxy business and some brine and energy assets, representing a total of $5 billion in revenue.

Methanol plant

OCI N.V.’s wholly owned subsidiary Natgasoline LLC plans to build a new greenfield world scale methanol plant in Beaumont, Texas. The plant is expected to have a capacity of up to 5,000 metric tons/day, or 1.75 million metric tons/year. Production is expected to start in late 2016.

World

Petrochemical plant

Grupa Lotos and Grupa Azoty have announced plans to build a $3.87 billion petrochemical plant by 2020 to reduce Poland’s reliance on imports. The plant will be built in Gdansk with help from state investment vehicle PIR, though most of the cost will have to be funded by debt and possibly a foreign partner. Financing is to be put together in 2015 after the groups complete a detailed feasibility study.

Expansion

Ineos is building a new furnace at its petrochemical plant in Rafnes, Norway as it expands capacity to use ethane made from U.S. shale gas it will store in a gas tank under construction at the site. The company is building an ethane storage tank that will enable the plant to produce 570,000 tons/year of ethylene. The extra furnace will enable it to produce 620,000 tons/year. The Norwegian plant currently houses 11 furnaces that process ethane gas and some oil-based liquids into ethylene. By the end of 2015, the company will have built a twelfth at the site. The total investment Ineos will make is around $160 million.

Liquid cracker

General Electric Co. and Carbon Holdings have signed a $500 million agreement to provide support in the building of the world’s largest liquid cracker at a petrochemicals complex on the Gulf of Suez. The naptha cracker project is part of the Tahrir Petrochemicals Complex worth $4.8 billion. The construction of the cracker is said to begin sometime in 2014 and construction is expected to take approximately 50 months. The new plant will have an annual capacity of 1,360,000 tons of ethylene and polyethylene as well as significant quantities of propylene, benzene, butadiene and linear alpha olefins.

Frequently Asked Questions (Faq) About Liquefied Natural Gas (Lng)

Dec 03 2013 08:27 AM

Dear All,

LNG is a subject of great interest these days considering that it has become a primary source of energy for many countries deficient in fossil fuel based energy resources. It is also of interest because it is among the cleanest of all fossil fuel based energy resources when compared with other fossil fuel energy sources such as coal and crude petroleum and its derivatives.

Today's blog entry tries to put in perspective what LNG is all about. The focus is on introducing what LNG is to new engineers starting their career. The blog entry has been made in the form of 'frequently asked questions' related to LNG. Details are excluded and certain web references are provided as hyper links which can guide the readers where to look for more details. Here goes the FAQ:

Q1. What is LNG?
A1. Liquefied Natural Gas (LNG) is natural gas (NG) that is cooled to the point that it condenses to a liquid.

Q2. What are the conditions for natural gas to be converted to LNG?
A2. Natural gas condenses to a liquid i.e. becomes LNG at a temperature of approximately -161°C (-256°F) at atmospheric pressure (101.325 kPaa).

Q3. Why is it required to convert natural gas to LNG?
A3. Liquefaction of natural gas to LNG reduces the volume of natural gas by approximately 600 times thus making it more economical to store natural gas and to transport gas over long distances for which pipelines are not economically feasible or there are other constraints.

Q4. How is LNG stored?
A4. LNG is stored in double-walled storage tanks at atmospheric pressure. The storage tank is really a tank within a tank. The annular space between the two tank walls is filled with insulation. Refer the link below for more information on LNG storage tanks:
http://en.wikipedia....NG_storage_tank

Q5. What materials are used to construct LNG storage tanks?
A5. The inner tank in contact with the LNG is made of materials suitable for cryogenic service and structural loading of LNG. These materials include 9 percent Nickel Steel, aluminum and pre-stressed concrete. The outer tank is generally made of carbon steel or pre-stressed concrete.

Q6. How is LNG transported by ships?
A6. LNG tankers are double-hulled ships specially designed to prevent leakage or rupture in an accident. The LNG is stored in a special containment system within the inner hull where it is kept at atmospheric pressure and cryogenic temperature (-161°C). For more details refer the following link:
http://en.wikipedia....iki/LNG_carrier

Q7. What is re-gasification of LNG?
A7. LNG has to be converted back to natural gas by warming in a controlled environment at the receiving and re-gasification terminal. The LNG can be warmed by passage through pipes heated by direct-fired heaters, or pipes warmed by seawater, or through pipes that are in heated water.

Q8. How is LNG quantified for trading (selling / buying) in the world market?
A8. LNG is generally quantified for trading on a mass basis in terms of millions of tons

Q9. Is there an approximate conversion for LNG mass to NG volume at standard conditions of 1 atmosphere pressure and 60°F?
A9. The approximate conversion for LNG mass to NG volume at standard conditions of 1 atmosphere pressure (14.7 psia /101.3 kPaa) and 60°F is as follows:

1 Metric ton of LNG or 1000 kg of LNG = 48,700 Scf of NG = 1379 Sm³ of NG

Note: Exact conversion depends on natural gas molecular weight

Q10. Is LNG flammable?
A10. LNG when suddenly released from its containment to atmosphere at ambient temperature conditions flashes and forms a vapor-air mixture. This vapor-air mixture forms a visible vapor-air cloud. As the vapor cloud gets warmer in contact with the ambient air it gets lighter than air and rises. A flammable vapor-air mixture can only form if the natural gas vapor concentration in the vapor-air mixture is between 5% and 15% by volume of the vapor-air mixture. A vapor-air mixture with less than 5% by volume of NG cannot cause a flame or fire since the concentration of the vapor (NG) in the vapor-air mixture is not enough to start or sustain a flame or fire or in other words the vapor-air mixture is too lean. The value 5% by volume is thus called the Lower Flammability Limit (LFL) for natural gas. Similarly a vapor-air mixture with more than 15% by volume of NG cannot cause a flame or fire since the concentration of the air (oxygen) in the vapor-air mixture is not enough to start or sustain a flame or fire or in other words the vapor-air mixture is too rich. The value 15% by volume is thus called the Upper Flammability Limit (UFL) for natural gas.

Q11. Is LNG explosive?
A11. LNG in its liquid form is not explosive. When LNG forms a vapor-air mixture and is in a confined space with no means to disperse it can cause a vapor cloud explosion if exposed to a source of ignition. Again for the vapor-air mixture to explode, the vapor concentration of natural gas in the vapor-air mixture has to be between 5% and 15% by volume. Thus the term LFL / UFL is interchangeably used with the term Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL).

Q12. What are the main uses of LNG?
A12. LNG after re-gasification to NG is primarily used for power generation, home heating and as cooking gas.

For more details related to LNG in general refer to the links below:
http://www.beg.utexa...energyecon/lng/
http://en.wikipedia....ied_natural_gas

I have no claim whatsoever as an expert in the LNG field. This is a general information that has been provided in this blog. I will take questions from the readers and try to answer them to the best of my ability.

Happy reading.

Regards,
Ankur.

Pressure Drop Of Pseudo-Plastic Fluids In Pipes

Nov 14 2013 09:38 PM

Dear All,

Pseudo-plastic fluids are a type of non-newtonian fluids and account for a majority of the non-newtonian fluids commonly found in the chemical process industry and specifically in the food processing industry.

Today's blog entry provides a methodology to calculate the pressure drop of a pseudo-plastic fluid in a pipe. An example problem is solved at the end of the outlined method. Readers can use the example problem to develop a spreadsheet based calculation

For Pseudo-plastic non-newtonian fluids, the power law model is used to define the shear stress versus velocity gradient relationship. The power law equation is as follows:

τ = K*(dV/dy)ⁿ

^where:
τ = shear stress at distance y from pipe wall
K = flow consistency index
dV/dy = velocity gradient or shear rate
n = flow behavior index

For pseudo-plastic fluids n < 1, and for dilatant fluids n > 1. Since the apparent viscosity μ is the slope of the shear stress τ versus velocity gradient plot, we can calculate the apparent viscosity of a non-newtonian fluid that follows the power law from the following equation

µ =K*(dV/dy)^n-1

^or
K = 0.001*µ*(dV/dy)^1-n

where:
µ = Apparent Viscosity, cP
K = Flow consistency index, Pa.sⁿ
dV/dy = velocity gradient, s^-1
n = flow behavior index, dimensionless

Power-Law Reynolds Number:

Re_PL = 2^3-n*(n / (3n+1))ⁿ*((V^2-n*Dⁿ*ρ) / K)

where:
Re_PL = Power-Law Reynolds Number, dimensionless
V = Velocity of flow in pipe, m/s
D = Inside diameter of pipe, m
ρ = density of the fluid, kg/m³

Determining fanning friction factor 'f' for laminar flow of power-law fluids:

f = 16 / Re_PL

where:
f = fanning friction factor, dimensionless

Note:
The transition from Laminar to Turbulent flow for pseudo-plastic fluids is considered at a Reynolds number of 2100.

Determining fanning friction factor 'f' for turbulent flow of power-law fluids:

Refer attached chart

Friction Loss (in head) using Fanning friction factor:

h_f = 2*f*V²*L / (g*d)
where:
h_f = friction loss (in head) in the pipe, m (meters of liquid column)
L = Length of the pipe, m
g = Acceleration due to gravity, 9.81 m/s²

Example Problem:

A coal slurry is to be transported by horizontal pipeline. It has been determined that the slurry may be described by the power law model with a flow behavior index of 0.4, an apparent viscosity of 50 cP at a shear rate of 100 /s, and a density of 1442 kg/m³. What would be the pressure drop and the horsepower (HP) required to pump the slurry at a rate of 0.06 m³/s through an 8 in. Schedule 40 pipe that is 80 km long ?

Inputs:

n = 0.4
µ = 50 cP
dV/dy = 100 s^-1
ρ = 1442 kg/m³
D = 0.202 m (based on nominal pipe size in inches and Pipe schedule)
L = 80 km
Q = 0.06 m³/s

Results:
L = 80,000 m
K = 0.792 Pa.sⁿ
V = 1.87 m/s
Re_PL = 8025
f = 0.0048 (from chart)
h_f = 1358 m
ΔP = 192 bar
HP = 1153038 W = 1153 kW

Hope all of you have found this blog entry very informative. I look forward to comments from the readers of my blog.

Regards,
Ankur.

Chexpress - November 12, 2013

Nov 12 2013 03:24 PM

North America

Proposed fine

ExxonMobil faces $2.7 million in proposed fines from The Pipeline and Hazardous Materials Safety Administration for its March 29 pipeline spill in Arkansas. The federal regulator said it found nine probable violations of safety rules in the break in the Pegasus pipeline. The 95,000 barrel/day pipeline has been shut since spilling about 5,000 barrels of oil in Mayflower, Arkansas. Exxon is cooperating with the investigation, but is still reviewing the notice and has not determined its course of action. The company has 30 days to contest the allegations.

Layoff

Valspar Corp. has laid off about 25 of its Minneapolis, Minnesota corporate and sales workers in the last few weeks. The cuts are part of the company’s effort to restructure and shift resources. Affected workers include those in the corporate, finance and consumer sales units.

Plant closure

PolyOne Designed Structures and Solutions will close a Warsaw, Indiana plastics factory next year. The closing will put 110 people out of work. The company will cut jobs in stages, beginning in early January and ending about Sept. 30.

Proposed fine

The U.S. Labor Department’s OSHA has proposed more than $280,000 in fines against contractors working on a power plant in Berlin, New Hampshire. OSHA says workers were exposed to serious and potentially fatal injuries from cave-ins, falls, scaffold collapses, crushing, lead and electrocution hazards. No one was killed or seriously hurt, however. General contractor Babcock & Wilcox Construction Co. Inc. faces more than $116,000 in fines. The other fines were against subcontractors. A Babcock & Wilcox spokesperson says the company disagrees with the findings but will work closely with OSHA to resolve the issues.

Ethylene venture

Mexichem has entered into a joint venture with Occidental Chemical Corp. known as Oxychem. Oxychem will build a $1.5 billion ethylene plant in the United States. The plant, which will be in Ingleside, Texas should start operations in 2017.

World

Plant restart

Pertamina has restarted a refining and petrochemical complex in East Java, Indonesia owned by TPPI. The move is aimed at reducing imports of oil products and chemicals. The restart could help reduce the current account deficit in Indonesia, where import costs have been rising due to a weak rupiah. Pertamina signed an agreement with TPPI to use the facility for six months. The plant had been idled for nearly two years due to TPPI’s heavy debts. During the six-month timeframe, the plant will process 55,000 to 80,000 barrels of condensate/day and will produce about 1.5 million barrels of gasoil and fuel oil, 36,000 tons of liquefied petroleum gas (LPG) and 2.8 million barrels of light naphtha. A total of 530,000 tons of petrochemicals will also be produced.

Purchase

Unipetrol has agreed to buy partner Royal Dutch Shell’s 16.3 percent stake in Ceska Rafinerska for $27.2 million. This will boost Unipetrol’s stake in the Czech Republic’s only refinery to 67.6 percent. The deal is expected to be complete in the beginning of 2014.

Change in plans

Kayan has dropped plans to build an ultra-high molecular-weight polyethylene (UHMWPE) plant in Jubail, Saudi Arabia. In 2012, Kayan and Petrokemya, both affiliates of Saudi Basic Industries Corp. (SABIC), signed a memorandum of understanding to equally own and finance the project. Kayan said that preliminary results of an economic feasibility study were not in line with the company’s growth plans.

Branded Clothing And Accessories Versus Engineering Books & Journals

Nov 01 2013 01:54 PM

Dear All,

The title of my blog entry may sound quite strange and incomprehensible to many. However strange it may sound, there is a funny and also quite a sad fact about it which I am going to describe in the next few paragraphs.

I have a few excel spreadsheets which are available by paying a very nominal amount of money posted on the online store of "Cheresources". Considering the efforts I had to undertake to develop them, sometimes months to fine tune them to bring them to a certain level, the amount spent in buying them is nominal, at least in my opinion. This of course is entirely my opinion and obviously I am entitled to express my opinion on my own blog. Readers of my blog are free to disagree.

Now let us come to the real story behind this blog entry. Not so long back, I had received a couple of emails wherein the writers of these emails wrote that they were young engineers starting out their careers and their pockets were too small to afford buying these spreadsheets and whether I could provide them these spreadsheets free of cost. I had quite a rude shock reading these emails considering the fact that these spreadsheets are quite nominally priced per copy.

I had to reply to these mails and this is what I asked them when I replied to them. I asked them whether they were aware of clothing brands like Arrow, Van Heusen and Louis Phillipe. The names I was mentioning are the middle level brands in men's clothing and not the top brands such as Gucci, Armani, Versace etc. I asked them whether any one of them owned a shirt or trouser from these brands and what they had paid for buying them.

I had specifically asked this in my reply because I often see amongst the younger bunch of engineers whom I work with, wearing top brands of clothing and carrying top-of-the-line accessories. My own clothing is a ragged mix of unbranded clothing and branded ones. The branded ones are courtesy the lady of my house who happens to be in the field of fashion design and does not see eye-to-eye with me on how men should dress. Well, at least I have no counter for the persuasive charm of my spouse and most of the times I yield to the extravaganza she indulges on my behalf

A branded shirt or trouser can easily cost upward of 50 to 60 dollars. The spreadsheets on the online store of "Cheresources" are priced lower.

Then how does one explain the email that asks for a free copy of a paid engineering calculation. Well, the answer is quite straightforward. It is not the money but the importance of its utility to the young engineer or engineering student. A branded piece of clothing has far more importance than an engineering calculation or for that matter any engineering literature (books / journals). It is beyond any rational comprehension that something that could enhance one's career can be ignored at the cost of a glitzy piece of clothing. How can anyone forget that any ostentatious lifestyle is just an extension of his or her career? When I say this, I don't mean begetting money by illegal or immoral means.

I by no means am implying that young people should shun indulging themselves in good clothes and accessories. What I am trying to convey is that if one can spare money to indulge in these things one can certainly spare something to buy books & literature which can enhance their career. I follow this in my life. If I feel that a particular engineering literature is worth possessing, within my resources and helps me to broaden my engineering knowledge I will not hesitate to buy it.

Anyways, to conclude this blog entry, the email I had written to the persons who wanted the engineering calculations for free never replied back to my inquiries. I am still trying to guess whether they felt shamed by my inquiry or thought that what a cranky old geezer I am.

I look forward to comments from the readers of my blog.

Regards,
Ankur.

Chexpress - October 22, 2013

Oct 22 2013 06:37 PM

North America

Ammonia plant

BASF SE and Yara International ASA are considering a big ammonia plant on the U.S. Gulf Coast. While company officials have said everything is still under discussion, a current BASF factory would be the most likely site. BASF has plants in Beaumont, Pasadena and Port Arthur, Texas and in Geismar, Louisiana.

Gas project revamp

Imperial Oil Ltd. is looking at a major revamp of its Mackenzie gas project that would see the stalled northern venture reborn as part of an expansive liquefied natural gas (LNG) development. A shift to LNG is under consideration as the Mackenzie pipeline’s economics remain weak due to cheap shale gas across the continent.

Ethane cracker

Technip was awarded a contract by Sasol to supply its proprietary ethylene technology and front-end engineering design (FEED) for a grassroots ethane cracker. The cracker will be located at Sasol’s Lake Charles, Louisiana site. It is estimated to produce 1.5 million tons/year of ethylene.

Sale

Dow Chemical Co. will sell its polypropylene licensing and catalysts business to W.R. Grace & Co. for $500 million. This sale is part of Dow Chemical’s strategy to shed its non-core businesses. The polypropylene licensing and catalysts business provides technology and catalysts to make polypropylene, which is used to manufacture plastics and synthetic fabrics. As part of the deal, W.R. Grace will acquire Dow Chemical’s catalysts manufacturing plant in Norco, Louisiana and customer contracts, licenses, intellectual property and inventory. The transaction is expected to close by the end of the year, pending regulatory approvals.

World

VCM plant

Fluor Corporation’s ICA Fluor industrial engineering-construction joint venture with Empresas ICA, S.A.B. de C.V., signed a contract with Petroquimica Mexicana de Vinilo, a joint venture between Mexichem and Pemex, for the revamp of the vinyl chloride monomer (VCM) plant at the Pajaritos petrochemical complex near Veracruz, Mexico. ICA Fluor will be responsible for the engineering, procurement, construction, maintenance and commissioning services to bring the VCM facility to its capacity of 405,000 tons/year from its current nearly 200,000 tons/year. The project is planned to be completed in the fourth quarter of 2015.

Butadiene plant

MOL’s petrochemicals unit TVK will build a new butadiene plant in Tiszaujvaros, Hungary. The planned investment is $106.4 million. The new plant will have an annual capacity of 130,000 tons and will be opened in the second quarter of 2015.

Aromatics plant

A subsidiary of Foster Wheeler AG’s Global Engineering and Construction Group has been awarded a contract by Petrochemical Industries Company for a pre-feasibility study and a market report for a proposed aromatics plant in Kuwait. The study is scheduled to be completed in the fourth quarter of 2013.

Chexpress - October 8, 2013

Oct 08 2013 07:30 AM

North America

Regional sales office

Dow Chemical Co. has opened a new Southeast regional sales office at is Polyurethane Systems North American Headquarters in Marietta, Georgia. The Southeast Regional Sales Center is home to approximately 50 sales associates who will use the facility to host customer meetings, conduct team events and participate in sales training.

Acquisition

Emerson has announced its intent to purchase Virgo Valves and Controls, LTD. Virgo, a manufacturer of ball valves and automation systems, will operate within Emerson Process Management’s final controls business. Terms of the transaction were not disclosed.

Natural gas to liquids plant

Shell Oil Co. has chosen a site near Sorrento, Louisiana as the potential location for a $12.5 billion natural gas to liquids plant that would create 740 jobs. The company says it will decide after engineering studies and environmental permitting are done. The plant would create natural gas-based diesel and jet fuels along with specialty waxes and products used in plastics and detergents that are normally made from oil.

Ethylene cracker project

Fluor Corporation and JGC Corporation’s 50/50 joint venture was awarded an engineering, procurement and construction (EPC) contract by Chevron Phillips Chemical Company LP for its U.S. Gulf Coast Petrochemicals Project. The project consists of the ethylene unit (cracker) and associated offsite components to be built at Chevron Phillips Chemical’s existing Cedar Bayou complex in Baytown, Texas. The scope includes engineering and procurement for the outside batter limit as well as direct hire construction for the entire cracker project.

World

Polyethylene unit

Unipetrol has acquired technology and production rights for a new polyethylene unit and wants to pick a contractor for the project in the first half of 2014. Even after posting net losses in 2011 and 2012, the company laid out plans in June to invest almost $1 billion over the next five years in its petrochemical segment. Unipetrol signed a license agreement with Ineos for the right to use a production process and technology for the new polyethylene unit that will help increase utilization of its petrochemical steam cracker.

Investment

Odebrecht plans to spend $8.1 billion in Mexico in the next five years in what appears to mark the biggest investment pledge yet from a Brazilian firm there. The company will invest in petrochemicals, renewable energy, ethanol and sugar production and highway concessions.

Petrochemical plant

Alpek has agreed to form a joint venture through its subsidiary, Petrotemex, with United Petrochemical Company. The joint venture will build a purified terephthalic acid (PTA) and polyethylene terephthalate (PET) plant in Russia’s independent republic of Bashkortostan. Each company will invest $10 million to carry out a feasibility study for the plant, with construction subject to approval by the directors of both companies. The plant would have a maximum installed capacity of 600,000 tons each of PTA and PET and would use Alpek’s IntegRex technology. The plant would use locally sourced paraxylene (PX), with negotiations currently underway with JSOC Bashneft for the feedstock supply.

EVA and LDPE plant

Saudi International Petrochemical (Sipchem) has begun operations at its new 200,000 ton/year ethylene vinyl acetate (EVA) and low density polyethylene (LDPE) plant at Jubail Industrial City. The company completed the first phase, which includes installation and testing of major equipment and pre-manufactured modules, prior to completion of basic preparations for initial start up during the fourth quarter of this year.

The Flip Side Of Engineering Standards And Practices

Oct 07 2013 11:40 AM

Dear All,

I like to keep myself abreast of the latest engineering standards and practices from international organizations (API / ISO) and from engineering / operating companies. The best thing about them is I don't have to overload my memory trying to remember established engineering and design practices which are generally well documented in these standards. These standards also help me save time when I am involved in engineering design, and often I quote these standards in the engineering design documentation that I prepare. So reading, knowing and remembering (depending on how good your memory is) these standards apparently seems to be the key for success in any engineering work.

So far, so good. Now here comes the flip side. These standards and practices have been developed by fallible humans and are not commandments from god. These standards and practices have evolved over the years and are still getting refined which is evident from the revisions that periodically appear for them. These standards are also written, reviewed and approved by a group of people and organizations who claim that they are the best and most authentic source of information on the particular subject. I am not saying that the credentials of these people and organizations are questionable. My point here is, that there can always be a difference of opinion amongst indviduals or groups on how things should be done (read engineering design).

What "A" expresses as his opinion about the methodology to be adopted may not be agreed by "B" based on different experiences by "A" and "B". However, both "A" and "B" need to provide logical explanation of their ideas and be able to state benefits and disadvantages of their way of doing things. This is what we call as logical progression of any idea and the process of adoption / elimination of the idea based on the end goal to be achieved.

What I see today in the younger lot of engineers is the blind adherence to standards and practices without application of logic, functionality and end goal to be achieved. I do believe, that a lot of it has to do with lack of experience but to a certain extent it can also be attributed to finding a easy way out. It is there in the standard so who wants to take the pains to uncover the logic behind it.

When I mention all of this, I am not decrying the standards and practices. A lot of the engineering practices prevalent today and documented in these standards and practices have stood the test of time and have evolved and matured to the extent that trying to research them further is simply a waste of precious time, especially if you are an engineer.

My advice to the young entry level engineers is that when you read a standard or practice, try to analyze the logic behind it. Ask questions about it to the more experienced engineers. There will be occasions where even the more experienced engineer may say "Hey, I reckon this is the way it always has been and I can't help you anymore". It would be easy to give up if you get such an answer, but then think that everything has a logic and somebody out there knows that logic and you need to have the resilience to find out that logic.

Good luck to all of you young engineers in making the effort to find out the logic on what is written as a standard or practice. I will be more than happy to receive comments on this blog entry.

Regards,
Ankur.

Chexpress - September 24, 2013

Sep 24 2013 06:43 AM

North America

Packaging Center of Excellence

H.B. Fuller Company has decided to invest in a Packaging Center of Excellence in North America to address customers’ packaging adhesives needs across a broad range of applications, substrates and environmental conditions. The center is expected to open in early 2014 and will be the company’s fourth center focused specifically on customer collaboration.

Fire

A recent fire at Danlin Industries’ facility in Thomas, Oklahoma destroyed a chemical plant and caused small explosions, forcing the evacuation of about a dozen people from nearby homes, but resulting in no injuries. The fire started about three hours after the last employees left the facility. The entire facility burned down. The facility had nontoxic but highly flammable chemicals that are used in the oil and gas production industry. Authorities are still trying to determine the cause of the fire.

Gas-to-methanol project

Fluor Corporation has been awarded an engineering and design services contract by South Louisiana Methanol L.P. for a potential 5,000 metric tons/day methanol project in St. James Parish, Louisiana. Fluor is working to finalize the process design and complete preliminary design for the facility.

World

Isobutylene production unit

UOP LLC’s technology has been selected to produce key ingredients for fuels and synthetic rubber in China. Panjin Heyun New Material Co. will use UOP’s C₄ Oleflex process to produce isobutylene. The company will also use UOP’s Butamer process, which converts normal butane to isobutene, thereby maximizing the feedstock utilization of the UOP Oleflex process. The new unit is expected to start up in 2014 and will process approximately 400,000 metric tons/year of isobutene feedstock at its facility in Liaoning Province, China. UOP will provide the engineering design, technology licensing, catalysts, adsorbents, equipment, staff training and technical service for the project.

Refinery substations

Siemens has been awarded a turnkey contract by the Kuwait National Petroleum Co. (KNPC) to supply high-voltage substations at refineries south of the city of Kuwait. The $240 million project will provide reliable power supply to two of KNPC’s biggest refineries. The project is scheduled for completion in December 2015.

Cost cuts

Bayer is stepping up cost cuts at its MaterialScience unit to counter production overcapacity in the industry and high raw material prices. Bayer’s MaterialScience unit makes polycarbonate plastics for panoramic roofs in Daimler’s Smart and Mercedes SLK convertibles and for blu-ray disks. It is also the world’s largest maker of chemicals for insulation and padding foams.

Design Guide For Sizing Vertical Oil Treaters

Sep 23 2013 04:58 AM

Today's blog entry provides some guidelines for sizing of vertical oil treaters. The procedures described in this blog entry do not give the overall dimensions of the treater, which may include inlet gas separation and free-water knockout sections, dependent on the upstream separation vessels. However, they do provide a method for specifying heat input required and a minimum size for the coalescing section (where the treating actually takes place), and provide the design engineer with tools to evaluate specific vendor proposals.

Before going on to the sizing of the vertical treater let us understand the specific application of a vertical oil treater. The most common type of single-well onshore treater is the vertical treater, shown in the attached sketch. Vertical treaters are recommended where sand or other solid sediments are considered a potential problem.

Let us move on to the sizing equations for a vertical oil treater

Heat Input Requirements

Metric Units

q = 1100*Q_o*ΔT*[0.5*(SG)_o + (SG)_w*W_in /(100-W_in)] ----------1(a)

USC Units

q = 15*Q_o*ΔT*[0.5*(SG)_o + (SG)_w*W_in /(100-W_in)] -------1('b)

where:

q = Heat input, W (Btu/hr)
Q_o = Oil flowrate, m³/hr (BOPD)
ΔT = Temperature increase, ⁰C(⁰F)
(SG)_o = Oil specific gravity relative to water
(SG)_w = Water specific gravity
W_in = Inlet percent water cut, percent

Water Droplet Size

Metric Units
If µ_o< 7.0 x 10 ^–2Pa s, then d_m = 1361*W_c^0.33*µ_o^0.25 -----------2(a)
If µ_o≥ 7.0 x 10 ^–2Pa s, then d_m = 700*W_c^0.33 ------------2('b)

USC Units
If µ_o< 70cP, then d_m = 242*W_c^0.33*µ_o^0.25 -------------2('c)
If µ_o≥ 70cP, then d_m = 700*W_c^0.33 -------------------2(d)

µ_o = Oil viscosity, Pa s (cP)
d_m = water droplet diameter, microns
W_c = Outlet Water Cut, percent

Vertical-Settling Time Equation

Metric Units
d = 806,000*(F*Q_o*µ_o / (ΔSG*d_m²))^0.5 -------------------3(a)

USC Units
d = 81.8*(F*Q_o*µ_o / (ΔSG*d_m²))^0.5 ---------------------3('b)

where:
d = vessel minimum diameter, mm (inch)
Q_o = Oil flow rate, m³/h (BOPD)
µ_o = Oil viscosity, Pa s (cP)
ΔSG = Difference in specific gravity of oil & water
d_m = water droplet diameter, microns
F = short-circuiting factor
=1, with very good flow distribution and smaller than 1220 mm (48 inch) diameter
or
= d/1220 (d/48) for treaters over 1220 mm (48 inch) diameter
Note:
First solve Eqn 3 using F=1. If the value of d is less than or equal to 1220 mm (48 inch), this is the final answer. If the value of d is greater than 1220 mm (48 inch), then substituting F = d/1220 (F = d/48) into above Eqn 3 gives the following modified equation:

Metric Units
d = 5.33*10⁸*Q_o*µ_o / (ΔSG*d_m²) ----------------4(a)

USC Units
d = 139*Q_o*µ_o / (ΔSG*d_m²) --------------------4('b)

where:
d > 1220 mm (48 inch)

Note:
The height of the coalescing section for a vertical treater plays no part in the settling equation. The cross-sectional area of flow for upward velocity of the oil is a function of the diameter of the vessel alone.

Vertical-Retention Time Equation
The oil should be held at a temperature for a specific period of time to enable demulsifying the water-in-oil emulsion. This time can be best obtained by a laboratory bottle test. However, in absence of such data, 20-30 minutes is a good starting point.

Metric Units
d²*h = 2.12*10⁷*F*(t_r)_o*Q_o -----------------5(a)

USC Units
d²*h = 8.6*F*(t_r)_o*Q_o ------------------------5('b)
where:
h = height of coalescing section, mm (inch)
(t_r)_o = Oil retention time, minutes (minutes)

Re-arranging Eqn 5 by substituting F, we get

Metric Units
If d ≤ 1220 mm (F = 1) then
h = 2.12*10⁷*(t_r)_o*Q_o / (d²) ---------------------6(a)

If d > 1220 mm (F = d/1220) then
h = 1.75*10⁴*(t_r)_o*Q_o / (d) ---------------------6('b)

USC Units
If d ≤ 48 inch (F = 1) then
h = 8.6*(t_r)_o*Q_o / (d²) --------------------------6('c)

If d >48 inch (F = d/48) then
h = (t_r)_o*Q_o / (5.58*d) -------------------------6(d)

Note:
Part of the overall vessel height is required to provide for water retention. The removal of oil from the water is not of primary concern.

Water-Retention Time Equation

Metric Units
h_w = 2.12*10⁷*(t_r)_w*Q_w / (d²) ----------------7(a)

USC Units

h_w = 8.6*(t_r)_w*Q_w / (d²) -----------------------7('b)

where:
h_w = height of water, mm (inch)
(t_r)_w = water retention time, minutes (minutes)
Q_w = Water flow rate, m³/h (BOPD)

This concludes today's blog entry on sizing or adequacy check of vertical oil treaters, Readers are free to put up questions and I will try my best to answer them.

Regards,
Ankur

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Chexpress - September 10, 2013

Sep 10 2013 05:00 PM

North America

Fertilizer plant

Northern Plains Nitrogen is buying land next to Grand Forks’ municipal sewage lagoons. The group is planning a $1.5 billion nitrogen fertilizer plant. The plant will receive gas through an existing pipeline near the project site or directly from the western oil patch through a proposed pipeline.

Cracker plant

Shell Oil Co. is seeking ethane suppliers for its proposed petrochemical complex at an industrial site about 40 miles north of Pittsburgh, Pennsylvania. Shell is still a year or more away from making a final decision on whether to build the multi-billion dollar plant. Shell says securing enough ethane for the potential cracker plant is a key step. The plant would convert ethane from Marcellus Shale natural gas into more profitable chemicals such as ethylene.

Phosphates plant

Hubei Xingfa Chemicals Group plans to open a facility in Effingham County in Georgia. The company expects to develop its plant on 83 acres and will establish a production line to produce phosphates, which will be exported through the port of Savannah.

World

Maintenance

Saudi Basic Industries Corp. (SABIC) will close one of its two crackers at its Netherlands plant for maintenance later this month. The Olefins 3 cracker at its Geleen site will close for six weeks beginning September 15 for routine maintenance work. This is part of a $178 million upgrade to increase energy efficiency. The upgrade will reduce the cracker’s energy consumption by 8 percent and increase production by 2 percent.

Closure

Total has confirmed that it plans to close down its last ethylene-making unit at is Carline site in eastern France, effective the second half of 2015. Cheap U.S. ethylene is forcing European and Asian plants to rethink their output mix.

Oil refinery

Aliko Dangote, president of Dangote Group, signed a loan worth $3.3 billion from 12 Nigerian and international banks toward a $9 billion project that will give Nigeria its largest oil refinery and petrochemical and fertilizer complex. At the completion of the projects, Nigeria is expected to become self-sufficient in fertilizer and refined petroleum products as well as an exporter. The 400,000 barrels/day oil refinery and complex will become operational in 2016. The plant will also produce 2.8 million tons of urea for fertilizing crops and to produce polypropylene.

Power Consumption Of Vacuum Pumps

Sep 01 2013 10:59 AM

I am back on my blog after a wonderful holiday to Canada. I had a lot of fun staying in Vancouver and found BC to be a beautiful place.

Today's blog entry deals with quick but reliable estimate of the power consumption of vacuum pumps used in the chemical process industry. Some equations are presented below for the benefit of the readers:

Liquid Ring (NASH) pump:

BkW = 21.4*(SF)^0.924

Rotary Piston Pump:

BkW = 13.5*(SF)^1.088

where:

SF = 0.02-16 for "Liquid Ring (NASH) pump" and SF = 0.01-4 for "Rotary Piston Pump"

SF is defined as the "Size Factor" and can be calculated as follows:

SF = m / P; kg/ h/torr

where:

P = Operating pressure of system evacuated, torr (mmHga)
m = Air equivalent flow rate, kg/h

"m" can be calculated as follows:

m = G*sqroot((273.15+T)*28.96 / (293.15*MW))

where:

G = flow rate of the process gas being evacuated, kg/h
T = temperature of the process gas being evacuated, ⁰C
MW = molecular weight of the process gas being evacuated

The value of 293.15 in the equation indicates a reference temperature of 20 ⁰C for air equivalent flow which is recommended by the "Heat Exchange Institute" (HEI) for vacuum systems.

This concludes today's blog entry and I look forward to comments from the readers.

Regards,
Ankur.

Chexpress - August 27, 2013

Aug 27 2013 09:10 PM

North America

USGC petrochemical project

Chevron Phillips Chemical Company LP has received air permits from the Texas Commission on Environmental Quality (TCEQ) for its planned ethane cracker and polyethylene units. This is in addition to the greenhouse gas permit the Environmental Protection Agency granted for the cracker earlier this year. Pending final board approval, the 1.5 million metric tons/year ethane cracker would be built at the Chevron Phillips Chemical’s Cedar Bayou facility in Baytown, Texas. The new polyethylene facilities, each with an annual capacity of 500,000 metrics tons, would be built on a site near the Chevron Phillips Chemical Sweeny facility in Old Ocean, Texas. The estimated date for the project’s completion is 2017.

Acquisition

Panda Power Funds will begin construction immediately on an 829-megawatt natural gas-fired power plant in Bradford County, Pennsylvania after acquiring the project from Moxie Energy and completing financing. The Panda Liberty generating station is expected to begin commercial operations by early 2016. This is in addition to the recently announced 859-megawatt gas-fired plant in Maryland, subject to financing and other conditions.

Explosion

A 10,000-gallon fuel oil tank exploded at Brownies Oil Co. The tank went flying across a road, killing a worker who was welding nearby. The man died from blunt-force trauma to his head. No one else was injured or killed. The tank spilled 7,500 gallons of fuel and flooded a dike encircling the area, but the spill was contained.

World

Coal-to-chemicals projects

China Coal Energy is stepping up investments in downstream coal-to-chemicals projects amid an oversupply and declining coal prices. The budget this year for projects to expand chemicals production has for the first time exceeded that for coal mines – 17.4 billion yuan for coal-to-chemicals projects versus 3.2 billion yuan for coal mine development. The chemicals include methanol, polypropylene and polyethylene.

Carbon capture-and-use plant

Saudi Basic Industries Corp. (SABIC) has hired Linde Group to build the world’s largest plant for capturing and using climate-warming carbon dioxide. An affiliate of SABIC, the United Jubail Petrochemical Company, plans to capture around 1,500 tons/day of carbon dioxide from ethylene plants and purify it for use in SABIC-owned petrochemical plants in Jubail. The carbon capture and utilization plant will prevent about 500,000 tons/year of the gas from being released into the atmosphere.

Gas pipeline

Construction of a gas pipeline from Sheberghan gas field in Afghanistan to Tajikistan was recently discussed at a meeting between Ministers in each country. The parties discussed various issues of cooperation in the energy sector. According to preliminary estimates, the overall cost of the project could be up to $300 million.

Chexpress - August 13, 2013

Aug 13 2013 07:19 AM

North America

Contract

A subsidiary of Foster Wheeler AG’s Global Engineering and Construction Group has been awarded an engineering, procurement and construction (EPC) contract by Enterprise Products Operating LLC for a propane dehydrogenation unit (PDH) and associated power, utilities and infrastructure at a plant in Mont Belvieu, Texas. The contract value was not disclosed. The construction will be executed through Foster Wheeler’s combined use of direct-hire labor and subcontractors.

Contract

A subsidiary of Foster Wheeler AG’s Global Engineering and Construction Group has been awarded a contract by The Dow Chemical Company to provide detailed engineering, procurement and construction management (EPCm) services for the LA-3 Crack More Ethane (CME) project at Dow’s Plaquemine petrochemical facility in Louisiana. The project is aimed at improving the plant ethane flexibility to take advantage of low-cost feedstock. The scope includes brownfield additions and retrofit modifications to the plant. The contract value was not disclosed.

Sale

ConocoPhillips is selling its stake in a Canadian oil sands project to Exxon Mobil Corp and Imperial Oil Ltd for about $720 million. The all-cash deal involves the sale of 226,000 acres of undeveloped land known as the Clyden oil sands leasehold. After the deal closes, Exxon Canada will own a 72.5 percent interest in the land, with Imperial controlling the rest.

World

Gas Chemical Project

The Irkutsk region will provide assistance to LLC Irkutsk Oil Company (INK) on a 120 billion ruble project to build a gas chemical complex near Ust-Kut, Russia. INK is currently researching the possibility of implementing such a project and is starting to draft a feasibility study for a potential investment project aimed at developing gas reserves at the Yaraktinskoye, Markovskoye and West Ayanskoye hydrocarbon deposits. The project entails the construction of a comprehensive gas treatment unit. INK expects to start supplying pipeline gas to Ust-Kut in the first half of 2016.

Contract

The National Methanol Company, a manufacturing affiliate of the Saudi Basic Industries Corporation, has awarded the engineering, procurement and construction contract for its polyoxymethylene (POM) project to an unnamed company. This brings National Methanol Company closer to producing high-strength, low-friction engineering plastic. The project is an expansion of the company’s existing operations as a joint venture between Sabic, CTE and Duke Energy. The POM plant is expected to have an annual capacity of 50,000 tons.

Project Delay

Petronas will start up its $19 billion petrochemicals complex in Malaysia in 2018 – a further delay in the country’s largest-ever infrastructure project. Petronas had already put back the project from late 2016 to early 2017. The project has apparently been complicated by the need to secure water supplies as well as cater for proposed international partners.

An Introduction To The Concept Of Double Jeopardy In Process Safety

Aug 05 2013 12:14 AM

Most Process and / or Safety engineers have to perform an analysis for the scenario or case related to the application of a safety relief device during their engineering career. In the chemical process industry, majority of the cases or scenarios for safety relief device are well defined based on experience gathered over the years for operating various types of chemical process plants including oil and gas separation plants, petroleum refineries, petrochemicals, fine chemicals, pharmaceuticals etc. Some such cases or scenarios frequently encountered in the chemical process industry are:

1. External Fire
2. Blocked Outlet
3. Gas Blowby
4. Control Valve fail Open
5. Hydraulic expansion due to uncontrolled heat input also called thermal expansion
6. Utilities Failure (Single or Multiple)
7. Power Failure (Partial or Complete)
8. Tube Rupture
9. Runaway Reactions
10. Check or Non-Return Valve Failure (reverse flow)
11. Vaccum generation due to Steam-Out

The above are some of the more common scenarios identified and studied in the chemical process industry for providing and sizing suitable safety relief devices.

However, the identification of a failure scenario for a given chemical process plant / equipment is something that requires experience on the part of the process or safety engineer. The experience that I am mentioning comes in the form of either engineering, constructing and operating or all of these for a similar plant / equipment. Often lack of experience results in either overlooking a credible failure scenario, or to cook up failure scenarios that are unrealistic and cannot stand logical scrutiny.

To avoid the uncertainties in defining and analyzing failure scenarios many top engineering and operating companies have pre-defined the failure scenarios for a plant / unit / equipment in their engineering manuals based on their own experience in engineering, constructing and operating a chemical process plant. While this simplifies the task in terms of the time taken for the safety analysis and consequent action for a safety relief device, it is also detrimental to the engineer because he or she is not allowed to use his or her analytical skills to determine a probable failure case.

Coming to the main subject of what is a double jeopardy with reference to the failure analysis of a plant / unit / equipment for providing a safety relief device. I would define it as follows:

The simultaneous application of two unrelated failure events for sizing or adequacy check of a safety relief device for a plant / unit / equipment is called double jeopardy.

In the above definition the key word is "unrelated". What do we mean by "unrelated"? It is not easy to identify what is related and what is unrelated. This is where the experience of the engineer counts and also the practices followed by the chemical process industry based on years of operating experience for a similar process plant / unit / equipment.

However, some basic unrelated scenarios can easily be identified. I will provide some very basic examples of double jeopardy which most new process engineers can easily understand.

A. Consider the example of a condenser supplied with cooling water for condensing the process vapors from a distillation column. Let us say that due to partial power failure, the cooling water pump(s) supplying cooling water to the condenser fail and there is a loss of cooling water to the condenser. Let us also take note that the column has a reboiler with steam fed at a controlled rate by a steam control valve for heating the column bottom contents. Can we imagine a combination scenario that when cooling water to the condenser fails at the very same time the steam control valve to the rebolier fails in the open position causing more process vapors to be generated in the column? What would be the relief rate that should be considered for the relief valve provided on the condenser? Should it be the normal vapor from the column top going to the condenser or should you consider the excess process vapors formed due to uncontrolled reboiler heating by steam control valve failing open at the very same time? The answer is quite simple. The flow rate for the relief device will be the vapor flow rate based on the normal vapor flow rate to the condenser when the cooling water failure occurred.

The partial power failure causing stoppage of cooling water supply to the condenser and the failure of the reboiler steam control valve in open position at the same time is highly improbable and as such can be considered as two "unrelated" events. It is highly unlikely that when the condenser cooling water supply fails, at the very same time the reboiler steam control valve will fail open, leading to abnormally high vapor flow from the column top.

B. A remotely located sales gas pipeline requires planned pigging intermittently. Permanent pig launcher and pig receiver are provided for this purpose. Administrative procedures and mechanical interlocks are in place to ensure that the pig launcher and receiver drain valves remain locked closed before pigging is started. The mechanical interlock ensures that the launcher or receiver cannot be pressurized by opening the gas supply line valve to them unless the drain valves are closed. The drain valves from the launcher and receiver are connected to a covered local pit respectively. There is a degassing local vent from the pit raised to a safe location height of 3 m. Due to administrative procedure failure error as well as mechanical interlock failure, the drain valve on the pig launcher is inadvertently opened during pigging and excess vapors are released from the degassing vent. At the same time accidental ignition occurs at the vent tip due to an ignition source. To prevent thermal radiation hazards to personnel in the surrounding area near the jet fire from the vent, a radiation contour study is mandated which suggests that to mitigate thermal radiation hazard from the jet fire the vent height must be raised to 18 m.

How credible is this scenario? Some might argue that this is perfectly credible and the degassing vent height needs to be raised based on the radiation contour study recommendations. I would say that this is not credible and a clear case of double jeopardy and I present the following reason for this:

The pigging operation is intermittent. It is a planned exercise with administrative measures as well as mechanical interlocks in place to ensure that drain valves are closed prior to start of pigging operation. Simultaneous failure of administrative measures and mechanical interlocks is unrelated and hence not credible. Presence of an ignition source at the vent tip and leakage of gas from the drain valves during pigging at the same time is unrelated and hence not credible.

The logic for relief scenarios needs to be developed based on the aforementioned methodology. Newcomers to process safety engineering should remember that one of the most challenging tasks in process safety engineering is to analyze the credible relief scenarios and identify what is double jeopardy and reject such scenarios which involve double jeopardy.

Hope this gives some idea to new entrants in process safety engineering of what "double jeopardy" is all about.

Anticipating a lot of comments from the readers of my blog.

Regards,
Ankur.

Guidelines For Fuel Gas Supply To Gas Turbines

Jul 28 2013 10:36 AM

Gas turbines (GT) are expensive and a major investment in any oil & gas, refinery, petrochemical or power generation unit. Any breakdown in gas turbines can lead to plant / unit production deferment or loss of power to the power grid if gas turbines are used for electricity genaeration, and spending large sums of money in repairs and overhauling.

The basic requirement for any gas turbine is the quality of fuel gas supplied within the design parameters specified for fuel gas for the given gas turbine. Most gas turbine breakdown problems during normal running are associated with large variations in fuel gas parameters from the design parameters as specifiied by the gas turbine manufacturer.

Let us come to specifics on what are the basic fuel gas quality parameters which need to be controlled or maintained and what are the means to exercise such control over fuel gas quality. These are listed pointwise below:

1. Gas turbines designed for high btu / joule gas (natural gas or high pressure process gas) provide an optimum performance when the calorific value of the gas is high. The efficiency and performance of such turbines is directly affected by the calorific value of the gas.

2. Gas turbine manufacturer's specify a minimum fuel gas pressure at their battery limit. In case, the available gas pressure is not sufficient to meet the requirements specified by the GT manufacturer, pressure of the available gas may require to be boosted up using a booster compressor to meet the requirements.

3. Fluctuations in the fuel gas Wobbe Index as an indicator of heating value should be kept at a minimum (typically ±5% is acceptable for streams supplying gas turbine fuel). Gas turbine fuel is controlled on a volumetric basis and performance problems can occur when the Wobbe Index fluctuates widely. The gas turbine manufacturer will provide specific guidelines on acceptable Wobbe Index fluctuations. Wider Wobbe Index fluctuations may require fuel gas blending facilities or separate fuel gas manifolds and associated modification to the combustor nozzles.
For definition and values of Wobbe Index refer the link below:

http://en.wikipedia....iki/Wobbe_index

http://www.engineeri...ndex-d_421.html

4. In cases where the fuel gas contains, sulfur compounds (H₂S, mercaptans etc), metals and particulates, extensive gas pre-treatment may be required to reduce them to low-ppm and / or sub-ppm values before allowing them to be used for GTs. The GT manufacturer will specify the maximum allowable values of these unwanted contaminants in the fuel gas.

5. Hydrogen content in the fuel can also impact system design. Typically, if the hydrogen content is less than 5% by volume, no special precautions are necessary. For higher values, the GT manufacturer may require an alternate starting fuel as well as design modifications and additional safety devices specific to hydrogen use. Potential swings in hydrogen content in the fuel gas can also impact the design of the combustion controls.

6. Fuel gas streams containing olefins should be avoided if possible, especially when specifying gas turbines with Dry Low NOx combustors. Olefins may polymerize and form deposits in small diameter orifices. If fuel gas with olefins cannot be avoided, the manufacturer can provide a design to accommodate the olefins provided the concentration is stable.

7. Any liquid and / or solid carryover with fuel gas to GTs can cause flashback and / or plugging of combustor nozzles This is particularly true with dry low NOx combustors.Modern installations for GTs have a Fuel Gas treatment system which is available as a skid mounted package and has several operations to prevent liquid / solid carryover. A typical fuel gas treatment skid would have the following equipment for gas treatment in the order of sequence described below:

a. Provide a Knockout drum (KOD) to remove bulk liquid in the gas as a first step

b. Downstream of the KOD provide high efficiency filter-separator to eliminate fine liquid droplets/mist and fine solid particles. Typically the filter-separator can be designed to remove 100% of all liquid droplets above 3 micron & 99.8% of all solid particles less than 3 microns

c. Downstream of the filter-separator a gas superheater (electric / water bath etc.) should be provided to ensure that the fuel gas temperature is at least 20°C (36°F) above its hydrocarbon dewpoint. Often, a temperature between 50 to 55°C is maintained which provides an adequate margin over the hydrocarbon dewpoint of the fuel gas.

d. Avoid loops or low points on the fuel gas piping running to the GT skid. If loops or low points are unavoidable provide low point drains with traps to prevent accumulation of any liquids.

e. Heat tracing of fuel gas piping downstream of the gas superheater may be required to prevent any condensation especially during winter.

f. It is a good engineering practice to change the material of construction of the fuel gas piping from carbon steel to stainless steel downstream of the filter-separator to prevent solids (rust) carryover to the GT.

The adherence to above guidelines will ensure a long and trouble-free operation of your gas turbine in terms of the fuel gas parameters as provided by the GT manufacturer.

Hope readers of my blog find this informative and I look forward to their comments and observations.

Regards,
Ankur

Chexpress - July 30, 2013

Jul 26 2013 07:33 PM

North America

FEED contract

Fluor Corporation has secured a front-end engineering and design (FEED) contract for Sasols world-scale ethane cracker and associated derivative chemicals facility at is Lake Charles Chemical Complex in Louisiana. FEED work is underway and is expected to be completed in late 2013. The new ethane cracker and associated facilities will allow Sasol to expand its differentiated derivatives business in the United States. Project start up and completion is forecasted in 2017 with the expected production of 1.5 million tons/year of ethylene with downstream derivative plants.

R&D center

Bayer CropScience will move its U.S-based research and development operations for vegetable seed and crop-protection products from Davis, California into an existing 164,000-square-foot facility in West Sacramento, California. The move is scheduled to happen in next years first quarter.

Isobutanol-blended gasoline

Gevo, Inc. has begun supplying the U.S. Coast Guard R&D Center with initial quantities of finished 16.1 percent renewable isobutanol-blended gasoline for engine testing. The U.S. Coast Guard R&D Center is using the Gevo-blended fuel as part of a 12-month, long-term operational study on marine engines that begin in June. The testing is being performed under a Cooperative Research and Development Agreement among the U.S. Coast Guard, Honda, and Mercury. The testing is focused on two of the Coast Guards platform boats 38-foot Special Purpose Craft-Training Boat and 25-foot Response Boat Small. Isobutanol is a biofuel that compared to ethanol, has higher energy density, lower RVP, and does not present the phase separation issues seen with ethanol. Testing will take place at the U.S. Coast Guard Training Center in Yorktown, Virginia.

Expansion

QualiChem has completed a major expansion of its headquarters, laboratory and manufacturing facilities. The companys Salem, Virginia facility is now 70 percent larger, with 35 percent more space for quality control, R&D laboratories and manufacturing, plus 50 percent more floor space for raw material and finished goods. The shipping and receiving area has increased by 233 percent and the company has added a 45-seat training and conference center.

World

Safety Milestone

Qatargas Laffan Refinery Companys Diesel Hydrotreater (DHT) project completed two million-man hours without any Lost Time Injuries. The DHT Unit is designed to produce diesel with less than 10 parts per million sulphur content with the Euro 5 environmental specification and will be built and integrated into the existing Laffan Refinery by 2014. The Unit will process 54,000 barrels/stream day of straight run Light Gas Oil feedstock from the existing Laffan Refinery 1 and the second planned refinery.

Acquisition

FMC Corporation has moved into the Omega-3 market with the $345 million acquisition of Epax. The senior management team at Epax will remain with the business. As part of the deal, FMC has entered into a long-term supply agreement with Trygg Pharma to provide Trygg with high-concentration Omega-3 fish oil for use as an active pharmaceutical ingredient.

Pipeline

The first phase of Oman Oil Refineries and Petroleum Industries Cos 280 kilometer Muscat-Sohar pipeline project is expected to be commissioned by the end of 2014. The project is expected to cost between $200 250 million. The first phase will include the construction of a pipeline between Mina al Fahal refinery and Muscat airport. Phase two of the project is currently in the engineering phase and will involve the construction of a pipeline between Mina al Fahal refinery and Sohar Refinery as well as an intermediate storage facility. The company hopes to commission the second phase by 2016.

Shale oil deal

YPF has persuaded Chevron Corp. to sign a long-sought deal to invest $1.24 billion in developing Argentinas shale oil deposits. The joint venture adds up to $1.5 billion overall. The YPF-Chevron venture will start with a $300 million pilot hydraulic fracturing project involving more than 100 wells in an area known as the Enrique Mosconi Cluster.

Chexpress - July 16, 2013

Jul 16 2013 06:23 AM

North America

Top Award

PPG Industries’ CEO Charles Bunch will be honored on Oct. 30 with this ICIS Kavaler Award by The Chemists’ Club. The award recognizes Bunch’s contributions to the chemical industry, including the spinoff of PPG’s commodity chemicals business and the acquisition of the architectural coatings unit of AkzoNobel.

Derailment scrutiny

The deadly derailment and explosion of an oil train in Quebec involved DOT-111 type tanker cars, which have come under scrutiny from transportation safety experts concerned with what they say is their tendency to split open during derailments and other major accidents. DOT-111 tank cars are the workhorse of the rail freight industry, hauling all sorts of chemicals and hazardous materials. A 1991 safety study revealed design weaknesses that accident investigators say almost guarantee the tankers will split open in major derailments. The National Transportation Safety Board (NTSB) has noted several problems with the type of car: its steel shell is too thin to resist puncture in accidents; the ends are especially vulnerable to tears from couplers that can fly up after ripping off between cars; and unloading valves and other exposed fittings on the tops of tankers can break down during rollovers. The rail and chemical industries and tanker manufacturers have voluntarily committed to safety changes for cars built after Oct. 2011 to transport ethanol and crude oil, including thicker tank shells and shields on the ends of the tanks to prevent punctures. But, the industry is appealing to regulators to reject the NTSB recommendations that the existing ethanol tankers built under the older specifications be modified or phased out.

Lawsuit

Two families are suing Allford Propane for more than $2 million over a deadly blast at a Eufaula, Oklahoma sandblasting company. The explosion in May left one man dead and another badly burned. The wrongful death lawsuit filed by the deceased man’s family seeks more than $1 million; the injured man’s family is also seeking more than $1 million. The suit blames the propane company for the explosion.

World

Investment

Eni plans to renovate and recover its Gela, Italy refinery. The aim of the project is to create an economically sound refinery capable of meeting the challenges of a competitive and evolving market. The refinery will also be redesigned to be more environmentally friendly and respectful to the local area. The project is estimated to involve an investment of €700 million and should be fully operational in 2017.

Purchase

The VETEK Group has completed its purchase of the Odesa Oil Refinery from Lukoil. The refinery is another link in the closed business cycle VETEK is building: from delivery of crude oil to production and retail sale of finished product. The Odesa refinery will be restarted soon. It can refine 2.8 million tons of crude oil/year. The plant was shut down in Oct. 2010 due to the economic situation that had developed on the oil-product market in Ukraine as well as due to changes to the oil delivery scheme.

Algae-based fuel

PTT has set its sights on introducing algae-based energy by 2017 and it is keen on setting up production facilities in Australia in the near future. The company is already in partnership with the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia’s national science agency, to develop a project involving algae-oil extraction. Currently, the research and development of fuel extracted from marine algae costs about three to four times as much as palm-oil-based biodiesel.

Lubricant plant

Sinopec has opened its first lubricant manufacturing plant outside Tuas, Singapore. The company has invested about 650 million yuan in the lubricant production facility, which will also serve as its Asia-Pacific hub for logistics and service. The plant is expected to employ between 140 and 150 people and will have an initial annual production capacity of 100,000 tons of lubricant.

How To Write A Plant Operating Manual

Jul 13 2013 06:48 AM

Most Process Engineers, specially the senior process engineers are required to write a plant operating manual for a new greenfield project during their career. Mind you, this is quite different from updating an existing operating manual for a brownfield project where the scope of the project is modification and debottlenecking. Updation of an existing operating manual is a simpler exercise compared to writing a new operating manual where you follow the format of the existing operating manual and only provide an addendum to the existing operating manual related to the scope of the project.

The real challenge lies in writing a new operating manual and that is where the experience of the process engineer comes into fore.

In this blog entry I have tried to put across general guidelines on preparing a plant operating manual based on my experience of writing a few of them. These guidelines are generic in nature and do not subscribe to any company philosophy for writing an operating manual.

Let us begin the exercise with what are the basic minimum requirements to start writing an operating manual

Following input documents are required during preparation of Operating Manual:

a. Basis of Design – Process Description
b. Process & Utility Flow Diagrams (PFDs and UFDs)
c. Piping & Instrument Diagrams (P&ID’s)
d. Deatiled process description from "Technology Licensor" for proprietary processes if applicable
e. Operating and Miantenance manuals of vendor equipment and packages (e.g. Instrument Air Package, Compressor Systems, Pumps, Water Treatment Plants, Fired Heaters etc.)
f. Function logic narrative provided by Instrumentation

Procedure:

Operating Manual is generally a Microsoft Word document.

Structure:
The Operating Manual is a structured document with a particular narrative style. The following is the sequence of the document:

- Coversheet with project title and document name i.e. Operating Manual
- 1^st sheet with project title, document name i.e. Operating Manual
- List of Contents which includes:
   . Abbreviations and Definitions
   . Introduction which provides an overview of the project
   . Process & Utility System Description
   . Process Control and Automation
   . Equipment Description
   . Start-Up Procedure
   . Normal Operating Procedure
   . Shutdown Procedure
   . Health, Safety & Environment (HSE)
   . Appendices

Abbreviations & Definitiions:
The abbreviations and definitions of terms used in the entire document are summarized here.

Introduction:
This section provides the brief overview of the project which includes the purpose of the facility and what it contains.

Process & Utility System Description:
This section describes in detail the overall facility. The narrative should be in such a manner that the description is in the correct sequence of the process for easy understanding. Utility systems which supplement the main process should be described as a separate sub-section. Wherever possible, process description should be supplemented by simple sketches showing the major equipment and process control for a particular unit operation. This enhances the understanding of the process.

Process Control & Automation:
This section provides the description of the overall controls required for the safe, reliable and uninterrupted operation of the plant / unit. This could include flow, pressure, temperature and level control of the plant / unit for the smooth operation of the plant / unit. Controls required for start-up, planned shutdown and to change plant / unit capacity should be mentioned. High and Low alarms for process operating parameters are also described in this section.

Plant section-wise or unit-wise control systems should be addressed in a sequential manner in order to explain the process control in continuity.

All process safety and shutdown interlocks, automation provided for emergency shutdown of entire plant or unit of the plant should be described in this section. An example of an emergency shutdown could be the description of the Fire and Gas Monitoring system which initiates the plant or unit shutdown.

Tag numbers of instruments used for process control and automation should be mentioned for sake of clarity.

Equipment Description:
This section provides the functional description of the individual equipment or group of equipment which form a unit operation in the overall context of the entire facility. Description could include operating and design conditions for the individual equipment.

Providing tag nos. for the equipment is recommended.

Wherever possible, sketches are recommended for the sake of clarity.

Start-up Procedure:
This section provides the description of the start-up procedure for the plant / unit under consideration:

The first sub-section of this section should address the readiness of the plant to be started-up. By readiness it is meant that the plant / unit is ready to accept the process or utility fluid, raw materials or reactants. This requires that the commissioning check-lists prepared for the plant / unit are ticked off and signed off by the start-up team. A list of the check-lists may be provided in this section which have been signed-off to indicate readiness.

The second sub-section should address the start-up of the utility systems prior to the start-up of the main process. Utility systems could include charging up headers for instrument air, cooling water, inert gas for blanketing / purging etc.

The third sub-section should address the start-up of the main process. This section should describe the valves (manual or automated) and instruments to be lined up for introducing the process fluid (e.g. hydrocarbons, chemicals) into the equipment or equipments (e.g. piping, vessels, tanks, reactors) of the plant / unit being started up.

Wherever applicable, reference of vendor documents for any equipment / package unit should be provided in this section.

Normal Operating Procedure:
This section provides the description of the normal operation of the plant / unit and indicates the parameters to be monitored for maintaining the product quality and operational reliability of the plant / unit.

Operating parameters should be mentioned for a particular equipment or unit or the entire plant in this section. Sketches describing the normal operation are recommended for the sake of clarity. Field logging and maintaining history records of critical process parameters from the DCS or SCADA need to be mentioned in this section. Requirements of manning a particular plant section or unit should be mentioned in this section including field monitoring intervals by operating personnel for a particular equipment or unit.

While describing any operation it is recommended that equipment, instrument and line tag nos. be mentioned for the sake of clarity.

Shutdown Procedure:
This section provides the description of the shutdown procedures to stop the operation of the plant.

The first sub-section of this section deals with normal shutdown due to either scheduled maintenance and / or inspection or modification / de-bottlenecking of the plant. In this sub-section, description should be provided for planned reduction / removal of inventory of the process fluids from the equipment or unit to be shutdown. This would include stoppage of fresh feed, gradual reduction of plant / unit throughput to minimise off-specification product and final draining and purging of the equipment / unit for the purpose of complete emptying prior to handing over for maintenance / inspection or modifications / de-bottlenecking.

The second sub-section deals with emergency shutdown procedures due to any emergency such as an external fire, water flooding, earth quake, loss of containment of process fluid (gas or liquid leak) etc. In this section description should be provided for the methods for isolation of equipment or unit due to either manual initiation or automatic initiation of an emergency. Manual initiation is emergency initiated by the operator of the plant / unit whereas automatic initiation is emergency initiated by automatic detection of an emergency such as detection of fire or gas leak by an automated Fire & Gas detection system.

Usage of tag nos. for equipment, valves and instruments while providing the shutdown procedure description is recommended.

Health, Safety & Environment:
This section describes the HSE aspects of the facility that need to be considered.

Health:
This sub-section relates to the health of the people and working in the plant or living in the vicinity of the plant whose health should be a concern for the management of the plant. This should also address the health and well being of animals and other living organisms present in the vicinity of the plant, for e.g. marine life in any water body which would be effected by the operations of the plant.

In this sub-section a brief description of toxicity of the chemicals used in the plant / unit, acceptable noise levels for humans and other animals, magnitude of injuries due to fire and explosion, first aid measures for treating injuries etc. should be provided.

Safety:
This sub-section relates to the safe start-up, operation and shutdown of the plant during its entire lifetime. This section should address the normal hazards those are encountered in day-to-day operations of the plant. This section should also address the safety measures available to prevent any accident.

Some of the normal hazards could be loss of containment of any hazardous fluid due to overflow, leak or rupture, static electricity build-up, accidental fall from heights, burns due to exposure to hot surfaces, exposure to toxic fluids while collecting samples and piling up of flammable solid waste (wood, paper, cloth etc.).

Description of safety measures should include:
- Special operating procedures for activities like sample collection and regular maintenance of rotating machinery
- Issuance of work permits for hot work and vessel entry
- Usage of personal protective equipment (hard hats, safety shoes, eye goggles, ear muffs, breathing apparatus etc.)
- Provision of field sign boards indicating the type of hazard
- Regular house-keeping
- Emergency evacuation procedures

Environment:
This sub-section describes the limits for discharge of hazardous solid, liquid and gaseous effluents to the environment based on local laws and regulations and procedures for compliance to them.

Appendices:
The appendices should preferably include the list of Process & Utility Flow Diagrams (PFDs / UFDs), Piping & Instrument Diagrams (P&IDs), Cause and Effect Diagrams (CEDs) and reference vendor documents, table for Alarm / Trip setpoints and lubrication schedule.

The above mentioned guidelines should help a process engineer to get started on a plant operating manual.

Readers of my blog are welcome to provide their experiences of writing a plant operating manual and I look forward to their comments and observations.

Regards,
Ankur.

Design Guidelines For Tank Truck Loading Terminals

Jun 25 2013 09:03 AM

I have been away for 3 weeks from my blog. Well, was busy on the workfront as well as on personal matters. Travelled home to India to be with the family. Spent some brief but quality time with the family who were keen to light one more candle on the cake.

Today's blog entry deals with design guidelines for tank truck loading terminals for petroleum products. Notable exclusions from these design guidelines are LP Gases & Cryogenic Liquids.

The guidelines are provided stepwise for the sake of clarity:

Step 1: Establish the product movement by road for a given design year

The following sub-steps need to be determined:

a. Volume per year of each product
b. Peak volumes and time duration
b.1 Peak arrival frequency (trucks per hour)
b.2 Volumes for the peak period

Step 2: Establish truck fleet characteristics & local factors governing road transport

The following sub-steps need to be determined:

a. Vehicle Characteristics
a.1 Truck capacities
a.2 Number of compartments per truck
a.3 Number of products per truck
a.4 Top or bottom loading
a.5 Overall Truck dimensions (Length, Width, Height)
a.6 Minimum turning radius http://www.google.co...iw=1024&bih=571

b. Local factors, preferences, regulations, regarding type of terminal operation
b.1 Terminal operation hours per day and days per year
b.2 Desired degree of terminal automation
b.3 Guidelines or Statutes for Vapor Recovery
b.4 Sequential or simultaneous truck compartment filling
b.5 Metering & Custody Transfer philosophy

c. Average / maximum allowable waiting time per truck during peak periods

d. Terminal Owner preferences or government regulations regarding terminal operation

Step 3: Predict arrival patterns based on local experience for customer demands within the delivery region

a. Peak arrival periods: Trucks per hour & duration (for example morning queues can represent the highest arrival frequency over a relatively short duration)

b. Seasonal Variations: These can be significant for certain products such as motor gasoline, heating oils, fuel oils, asphalts etc.

Step 4: Establish design or base case configuration

a. Group trucks by product loaded

b. Calculate average loading time per truck for each class of product
b.1 Assume one stop loading
b.2 Assume sequential compartment filling unless advised otherwise
b.3 Calculate filling time
b.3.1 Allow for low initial and final top-up rates (Refer attachment)
b.3.2 Base normal filling rates on local practice
- 30 liters/s (500 gpm) for truck capacity less than 15 m³ (4000 U.S.gallons)
- 50 liters/s (800 gpm) for truck capacity greater than or equal to 15 m³ (4000 U.S.gallons)
- Calculate filling time per compartment

= (Total Volume Loaded - Volume loaded in slow start / top-up period) / Loading Rate
(Assume start / top-up filling rate as 10% of normal filling rate)

- Total filling time = Filling time per compartment*Number of compartments

b.4 Include additional time for preparation and hookup (Refer attachment)

b.5 The reciprocal of the total occupancy time in hours gives the number of trucks per hour that can be loaded at each spot

c. For daily peak arrival periods, calculate the number of spots for each product class with 100% terminal utilization

No. of spots = (Peak Arrival frequency, trucks / hour)*(Arrival period, hours)*(Loading time per truck, hours) / (Arrival period, hours + Maximum Allowable waiting time, hours)

d. For peak arrival period in excess of 1-2 weeks, calculate the number of spots required for each product class based on a terminal utilization of approximately 50%

No. of spots = (Volume per peak period)*(Loading time per truck, hrs) / (Vol. per truck)*(Terminal open hrs per day)*(Terminal Open days per year)*(peak days/365)*0.5

e. For overall yearly average loading rates, calculate the number of spots required for each product class based on a terminal utilization of 35%

No. of spots = (Volume / yr)*(Loading time / truck, hrs) / (Vol / truck)*(Terminal opens hrs per day)*(Terminal open days per yr)*0.35

f. Select the highest number of spots resulting from the controlling case above rounded off to the nearest whole number.

g. Attempt to minimize the total number of stops based on the following considerations:
g.1 Reviewing requirements (peak volumes, peak periods etc.)
g.2 Combining spots based on low demand of one product class with another

Step 5: Examine the impact on terminal occupancy and waiting times for the following

a. Simultaneous filling with preset control
a.1 Multiple products per spot
a.2 Multiple loading arms per product per spot

b. Changed (Increased/Decreased) filling rates

Step 6: Other Considerations

a. Provision for future expansion
b. Provisions for washing or inerting trucks
c. Loading arm capacities based on standard arm configurations
d. Fire & Gas Detection and active / passive firefighting
e. Provision of locally or remotely operated emergency shutdown valves for each product line
f. Provision for electrical grounding at all loading spots

The aforementioned write-up tries to provide general guidelines on how to design a tank truck loading terminal. However, to repeat, these are very general guidelines and process engineers involved in design of tank truck loading terminals should follow the specific project requirements when provided to them as a design basis or concept for a given system.

Hope all of you enjoy this blog entry and looking forward to comments and discussion on this topic from knowledgeable members of the community.

Regards,
Ankur.

Chexpress - June 25, 2013

Jun 25 2013 06:54 AM

North America

Acquisition

Monsanto has acquired Grassroots Biotechnology for an undisclosed sum. The acquisition came after a long-term partnership between the two companies. Grassroots developed a gene-expression platform and other agricultural technologies to complement Monsanto’s portfolio. Research employees were transferred to Monsanto as part of the deal.

Plant blasts

Two chemical plant accidents in Louisiana – only a day part – killed three workers and left many more injured. The first explosion killed two workers at the Williams Cos. ethylene plant in Geismar. The cause is still unknown. While a massive fire raged, 300 workers were evacuated and 73 of them were taken to area hospitals. At the CF Industries nitrogen fertilizer plant in Donaldsonville, 10 miles away, one worker was killed and seven were injured when a temporary distribution manifold ruptured during the off-loading of nitrogen gas.

Investment

EcoDual Inc. will relocate its manufacturing assets in a new facility in Beaufort County, South Carolina over the next 18 months. The $13 million investment by the dual fuel conversion systems company is expected to create 307 new jobs over the next five years. The company’s dual fuel conversion systems for heavy-duty, Class 8 trucks can help reduce fuel costs by allowing these vehicles to operate on a combination of diesel and natural gas while providing full torque and power.

Explosion

Two people were killed in a massive explosion at a fireworks warehouse west of Montreal, Quebec, leaving a huge plume of smoke visible for miles. A series of explosions subsequently leapt from the charred building after the initial blast at B.E.M. Fireworks. Two bodies were found in the wreckage. Nearly two hours after the blast, fireworks could still be heard exploding at the scene of the fire that continued to burn out of control hours after the explosion. Police ordered the surrounding community of Coteau-du-Lac evacuated and closed a nearby highway in both directions.

World

Electrical equipment supplier

Eaton has entered into an agreement with Sadara Chemical Company (a joint venture between Saudi Aramco and The Dow Chemical Company) to supply motor control, power distribution solutions and engineering services. Under the multi-million dollar agreement, Eaton will provide equipment and services to enhance the overall reliability and safety of Sadara’s fully integrated chemical complex currently under construction in Jubail Industrial City, Saudi Arabia. The Sadara complex will be the world’s largest integrated chemical facility ever built in a single phase. It will produce more than three million metric tons of value-added chemicals and plastics to serve the rapidly expanding energy, transportation, infrastructure and consumer products sectors.

Petrochemical complex

State Oil Company of the Azerbaijani Republic (Socar) will be investment $500 million in the building of an oil and gas refining and petrochemicals complex in Garadagh. The plan is for it to go into operation by 2021. It will have a gas refinery, an oil refinery and a petrochemicals plant. The plan is for a nuclear-powered generating facility to be built in order for them to operate autonomously.

Plant expansion

Jacobs Engineering Group Inc. was awarded a contract by Polimeri Europa UK Limited (Versalis group) to provide engineering, procurement and construction management (ECPM) services to support a major expansion at Polimeri Europa UK’s plant in Grangemouth, Scotland. Under the terms of the contract, Jacobs is providing EPCM services in collaboration with Polimeri Europa UK to support the installation of a new finishing line and the associated works. The expansion is expected to significantly increase Polimeri Europa UK’s rubber production capacity in Grangemouth.

Chexpress - June 11, 2013

Jun 11 2013 06:58 AM

North America

Workforce Training Program Funding

ExxonMobil will fund a $500,000 workforce training program to enable Houston, Texas’ leading community colleges to prepare thousands of local residents for jobs in the growing local chemical manufacturing industry. The incentive will build on the success of the Lee College ExxonMobil Process Technology Program that will benefit 50,000 students and educators in the next five years. Lee College will work with Houston Community College, Lone Star College, San Jacinto Junior College, Alvin Community College, Wharton County Junior College, Brazosport College, Galveston College and College of the Mainland to train students seeking certification or completion of degree programs for instrumentation, electrical, machinist/millwright, welding, pipefitting and other skills and competencies needed by the chemical industry. There are also plans to include area high schools in the program in the future.

Pipeline Contract

Wood Group Mustang has been awarded a contract by The Dow Chemical Company to provide services for construction of approximately 140 miles of ethane, ethylene, propane and propylene pipelines, associated interconnections, and station modifications between Dow Texas Operations in Freeport, Texas and facilities at Mt. Belvieu, Texas. The pipelines and station upgrades are part of construction for a world-class ethylene unit previously announced as part of Dow’s plans to further connect its U.S. operations with cost-advantaged feedstocks available from increasing supplies of U.S. shale gas. Wood Group Mustang will provide engineering, field services and construction management on the project. Completion is scheduled for late 2016.

Expansion

Chevron Phillips Chemical Company LP will expand its ethylene production by 200 million pounds by adding a tenth furnace to ethylene unit 33 at its Sweeny complex in Old Ocean, Texas. The new furnace will achieve lower emissions and incorporate Best Available Control Technology (BACT). Construction is targeted to commence within the next quarter with anticipated startup in 2014. The additional furnace will not add to the nameplate capacity of the facility; however, the increased operating factor should result in a net increase of 200 million pounds of ethylene availability to provide additional operational flexibility and reliability.

World

Ethylene Production

ExxonMobil’s Singapore Chemical Plant is now producing ethylene from the facility’s second world-scale steam cracker. The expansion is integrated with the existing petrochemical plant. During the next few weeks, the petrochemical complex will increase production at its three polyethylene plants, two polypropylene plants, a specialty metallocene elastomers unit and the expanded oxo-alcohol and aromatics units.

LNG Terminal

Plinacro has completed a concept design for its liquefied natural gas (LNG) terminal on the Adriatic Island of Krk. The Krk LNG terminal project is being developed by LNG Hrvatska, a 50/50 joint venture between Plinacro and HEP. The terminal will have a regasification capacity of 5.0 billion cubic meters of gas annually and is projected to cost $776.6 million. The environmental impact assessment and the preliminary design should be completed in July and August, respectively.

Pipeline Construction

Construction of the Nabucco-West gas pipeline may begin in 2015 if the Shah Deniz Consortium selects this pipeline as its route for the export of Azerbaijani gas to Europe. If selected, Nabucco will start getting equipment and materials ready in 2014 so that they can start building the pipeline in 2015 and start transporting gas at the end of 2018 or the beginning of 2019. The plan states that gas could be provided via the pipeline to countries through which the pipeline runs and to the Balkan countries, Slovakia, the Czech Republic, Poland, France, Germany, Ukraine and others. The Shah Deniz consortium is in the process of choosing between the Trans Adriatic Pipeline (TAP and Nabucco-West projects as an export route for Azerbaijani gas to Europe. Their decision is expected by the end of this month. The TAP project is designed to transport natural gas from the Shah Deniz field under State-2 through Greece and Albania to Western Europe. Nabucco-West is a truncated version of the Nabucco pipeline that envisages laying of pipeline from the Turkish-Bulgarian border to Austria’s Baumgarten.

Refinery Contract

Technip was awarded a contract by SCOP for project management consultancy (PMC) services for the engineering, procurement and construction (EPC) phase of the Karbala refinery in Iraq. This award follows the front-end engineering design executed by Technip in 2010. The scope of work will be done in two phases. Phase one includes issuing enquiries for the EPC contract, bids clarification, evaluation and contracts finalization with the EPC contractors. Phase two includes overall management of the EPC contract execution.

Natural Gas Pipeline Blowdown Time Calculation

Jun 02 2013 07:31 PM

I have posted a lot of excel spreadsheets on the Cheresources community related to process engineering calculations. I also have posted blog entries where I have outlined the steps along with equations to build an excel spreadsheet for various calculations.

The idea of posting blog entries with equations and calculation steps is to encourage young engineers to build their own spreadsheets and understand how excel can be a versatile tool to do all kinds of engineering calculations.

Let me share something about excel with you. I never had any formal training on excel. I am a self-taught person with bits and pieces of help from others who know excel equally well or more than me. The level of prowess that I have developed is due to practice and by making dozens of spreadsheets over the last few years. I still do not know how to write a macro or VB code in excel. I use the function library of excel and it has served me well till date. The conclusion I made over these years was the more you practice the better you get. Well it is a universal law applicable to any skill that anybody wants to acquire.

Enough of the lecturing on acquiring skills related to excel.

Today's blog entry is related to depressuring or blowdown time from a long-distance natural gas pipeline. Blowdown from a gas pipeline would be required under two circumstances. The first and most important would be an emergency blowdown for de-inventorying the pipeline due to an emergency such as fire, pipeline mechanical damage (rupture / displacement). The second would be a planned maintenance of the pipeline which would require the pipeline to be de-inventoryed before handing it over to the maintenance crew.

Normally permanent blowdown connections are provided for all long-distance pipelines along the pipeline route. Blowdown connections (piping, associated blowdown valves, restriction orifices) at dispatch and receiving stations are generally hooked up to the flare system at the station. However, most pipelines run through remote and uninhabited areas, where it is not practical to provide a flare system. Some sections of pipeline separated by block valve stations, which pass through remote areas, if required to be depressured or blown down, need to be vented to the atmosphere through cold vent lines provided with blowdown valves.

One exercise that a process engineer needs to do is to design or calculate the size of the vent line based on the time required to blowdown or depressure the system. Blowdown is a transient process where the pressure from the system to be blown down is reduced in time steps within an acceptable total time.

The blowdown process follows both the sonic process of pressure reduction and the subsonic pressure reduction. Sonic discharge refers to the initial stage during which the flow at the point of minimum effective vent area (usually the blowdown valve throat) is choked and the Mach number is necessarily unity. In other words, the ratio of pressure in the gas pipeline to atmospheric pressure is greater than the critical pressure ratio and thus flow is sonic. For high-pressure blowdown, sonic flow accounts for most of the blowdown time.

During blowdown the pressure in the gas pipeline decreases and the flow at the minimum area or restriction in the blowdown or vent pipe remains choked until the pressure ratio becomes less than critical. Then the flow is no longer choked and remains subsonic until the pressure in the pipeline reaches atmospheric at which point the blowdown or depressuring of the pipeline is complete.

Most process engineers well versed with HYSYS know about the HYSYS Depressuring Utility for doing depressuring or blowdown calculations to obtain blowdown time, flow rate, system / fluid temperatures.

Well what about those who do not have access to HYSYS and want to do depressuring calculations. Today's blog entry makes an attempt to remedy that to a certain extent by providing an excel spreadsheet to calculate the blowdown time from a long gas pipeline.

This excel spreadsheet however does not provide flow rates or system / fluid temperatures and is limited to providing the blowdown time from a given upstream pressure (pipeline pressure) to a downstream pressure (atmosphere) and for a given vent or stack line size. Despite its limitations, the calculated blowdown time is within 10% of the blowdown times as calculated by HYSYS for a number of cases and within the application limits of the equations provided in the spreadsheet. Further accuracy can be obtained if an iterative procedure is adopted for pressure reduction which has not been considered in the present version of the spreadsheet.

Before presenting the spreadsheet, many thanks to member "Alexsandres" who provided the link for the technical paper from which the spreadsheet was developed. Refer the link below where he has provided the link for the paper:

http://www.cheresour...-journal-paper/

I am hoping that the Cheresources members will like this spreadsheet and specifically those who are constrained by not having a sophisticated process simulation software such as HYSYS. I look forward to comments from the knowledgeable forum members.

Download the Excel spreadsheet in the File Repository here:

Gas Pipeline Blowdown Time Calculator 1.1

Category: Excel Spreadsheets

Last Updated Jun 10 2013 12:10 PM

Regards,
Ankur.