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#5255 Uploading Ms Excel Spreadsheets

Posted by Chris Haslego on 18 March 2006 - 05:08 PM

I've noticed that many of you are wanting to share Microsoft Excel files. You can upload them into your messages just like other files. This should simplify the process of sharing the spreadsheets rather than having to email them to one another.

#82070 How About An "in Development" Section In Downloads?

Posted by ankur2061 on 19 January 2014 - 01:14 PM

Sharing your work (calculations / excel workbooks) can be done only with an open heart and a mind free of suspicion.


It is outright hilarious when people claim that the calculation they have created in the form of an excel workbook is their original work. Most of the engineering calculations that we do today have their roots in the physical laws, principles, formuals, and equations developed by pioneers and researchers in the field of engineering and science long before many of us had even understood what engineering calculations are.


People who are developing calculations / excel workbooks are only organizing and representing the work in a proper sequence and in a manner which is easy to understand and present. Yes, it takes time and effort to do this, and those who have undertaken this task need to be appreciated.


I have never endorsed spoon feeding to young engineers because it allows them to think that there is an easy way out for everything. Many of the blog entries in my blog are related to engineering calculations where I have exhorted the engineers to prepare excel workbooks based on the calculation steps mentioned. For each and everyone of these blog entries related to chemical engineering calculations, I have developed an excel calculation workbook, which I have not shared for the very same aforementioned reason.


However, I do want to make a public pledge today. When my eyesight starts betraying me and my hands are no longer able to type on the keyboard of a computer, I would like to donate my entire set of chemical engineering calculation workbooks to "Cheresources" for Chris Haslego to use in a manner he deems fit for the good of the chemical engineering community.




#118338 Pressure Relief Valve Accumulation Pressure

Posted by Art Montemayor on 08 May 2019 - 01:32 PM



I highly recommend that you take Latexman's concise and terse response as an important one.  His comment is meant to be taken in jest.  He is precisely correct in his statement and I only take this time to add to his valuable advice.


It is very important that you learn and apply what his statement and recommendation implies.  I am certain that he is assuming that you have invested as much time and effort in the application of safety relief devices as he has, and for that reason I am attaching a document I prepared some time back in replying to a student that had problems with the same topic.  You rightfully show concern for the accumulated pressure realized in a pressure relief valve and you correctly give importance to the MAWP.   However, I believe you lack the knowledge of  how the MAWP is calculated and under what correct basic data and assumed conditions.  You also seem to not be aware of the usual and normal way a pressure vessel is subjected to a required hydrostatic test.  A hydro is far in excess of the MAWP.  So, can this be???


Experienced and knowledgeable engineers, such as Latexman, don't have disdain for the value of a pressure vessel's MAWP.  On the contrary.  They are aware and mindful of the precise conditions under which it is calculated, its specific intentions, and how it applies to engineering design and operations.  Please read the attached and you will further appreciate what he has stated.


Attached File  MAWP as Applied to PSVs.docx   107.56KB   84 downloads

#96123 Revision Calculos Tanque Api 650, Edicion 12, Marzo 2013

Posted by Rafael David on 17 June 2015 - 05:40 AM

Señor TALVI y demás miembros del Blog adjunto memorias de cálculos en Excel para su revisión técnica, ingeniería y conceptos que ustedes consideren que se deben tener en cuenta en este diseño.


La idea es que revisen estas memorias y la complementen con sus conocimientos y experiencia.


En este proyecto que estoy desarrollando se van a construir doce tanques así: Cuatro (4) de acero al carbono en SA-36, uno (1) en Acero inoxidable  tipo 316 y seis (6) en PRFV o fibra de vidrio, con capacidad cada uno de 42.5 ton. para almacenar productos para químicos para tratamientos de aguas.


En las memorias están los datos del este producto del tanque N° 1 de acero al carbono. Mi objetivo es que este software en Excel le sirva a todos los miembros de la comunidad.


a la espera de su valioso aporte.





Attached Files

#88971 Chemical Engineering Plant Cost Index (Cepci)

Posted by breizh on 25 August 2014 - 05:59 PM



Year 2013 : 567.3

Final April 2014 : 573.6

Preliminary May 2014 : 574.4



#60483 How About An "in Development" Section In Downloads?

Posted by Chris Haslego on 24 May 2012 - 08:56 AM

I have many, many spreadsheets from visitors that have tons of great information in them, but aren't necessarily ready to be opened and used as they exist. Some may need just a little work, some may need a lot of work. Many of them are well referenced in terms of methodology being used.

However, some people may be working on similar projects and may find these helpful. My hope would be to release them in the Downloads section (clearly marked as "Development Items") and to see if the community can work together to turn these into polished projects.

I thought I'd start by collecting initial feedback on the idea. Let me know what you think. These titles would only be visible to registered members of the community.


#121749 Compressor Blocked Discharge

Posted by Jiten_process on 27 September 2020 - 03:52 AM



I think you are talking about centrifugal compressor. Blocked outlet scenario for centrifugal compressor must be evaluated very carefully as there are certain consideration behind the deriving the worst case blocked outlet relief case. 


Usually, you have compressor discharge pressure VS flow curve at normal operating conditions. Blocked outlet can occure when you are off your normal operating coditions. Hence, blocked outlet scenario should consider below cases 


1) compressor being operated at maximum suction pressure (higher than normal suction pressure)

2) compressor being operated with fluid with different molecular weight. specially higher than normal case

3) compressor being operated at its maximum speed. 


Usually, you should ask vendor about the curve with above consideration and confirm with vendor for the accurate blocked outlet relief flow. otherwise, based on the efficiency data by compressor compressor vendor, you can simulate it for governing case considering power constraints. Note that, in absence of vendor supplied curve, if you are using HYSYS to evaluate the relief flow, it must be carefully done given that the procedure is different for fixed speed compressor vs variable speed compressor. Also, it it two stage compressor, 2nd stage discharge relief flow depends on 1st stage compresor operating condition. I can give you quick method for fixed speed and single stage compressor using simulator as below


- take the maximum suction pressure at suction

- model compressor curve in the hysys given by the vendor

- keep discharge pressure same as relief valve set pressure or relieving pressure

- keep increasing the flowrate till the time you see power calculated by simulator is equivalant to maximum power constraints by vendor. 

- add 5% margin on calculated flowrate to abosrb any uncertainly/error. 

- repeate the above steps for lowest molecular weight and highest molecular weight and use PSV sizing for governing case


Above step, can give you the relieving temperature also readily from simulator. 


If you are at proposal stage and dont have vendor info, you can use guidline as - for variable speed compressor relief flow rate can be in the range of 1.5-1.8 times the design flow rate and for fixed speed machines, this can be in the range of 1.3 to 1.5 times design flow rate.


Trust this helps. 

Good luck. 

#117857 Chemical Engineering Plant Cost Index Cepci Of 2016 And 2017 ?

Posted by breizh on 01 April 2019 - 03:18 PM

hi ,

hope this is helping you and others.

Good luck


Attached Files

#117665 A Few Storage Tank Related Questions

Posted by Art Montemayor on 14 March 2019 - 01:37 PM



Your query is like questions raised by lay persons or journalists trying to inquire about technical process operations and not like an engineer would look at a process problem or application.  I am forced to revert back to engineering basics in order to address your questions:

  • I don’t care what the “other websites” state about the application of storage tanks.  The statements are totally out of line.  The statements don’t take into consideration the actual fluid stored and the conditions it is stored under.  These are the first and most important basic data you have to know - and you fail to state that.
  • The next important basic data is the size of the storage requirement.  What is the storage capacity in question?  You also fail to identify that.
  • The best engineering advice I can give you is to never, never ever generalize when you deal with an engineering query.  Be specific and identify all the required basic data before answering or commenting on a process operation.  Your failure to do this is why you are so perplexed about applying storage tanks.  Without specific basic data you will always be wandering around without fully understanding the application.
  • A fluid’s vapor pressure at the required storage pressure is often what determines the type of storage tank best suited for the application.  LPG and other liquefied petroleum gases are stored in pressure vessels (such as spheres or bullets) when their vapor pressures are within the range of conventional vessel design pressures above the fluid’s vapor pressure at ambient temperatures and the application suits ambient storage temperatures.  If the quantity is large and the need and economics suit the application, then cryogenic temperature storage at relative ambient pressures may be attractive.  Practical sense economics always reigns in engineering applications - not generalizations.
  • Your reasoning for using a floating roof tank is wrong.  If the fluid has a high vapor pressure, a pressure vessel may be called for.  Use your common sense: an API storage tank with a floating roof is limited to relatively low pressures.  The floating roof is to compensate for varying liquid levels that may cause a partial vacuum and allows for vapor space expansion - as well as for large inventories.  The nature and properties of the stored fluid is what determines the type of floating roof - as well as the economics involved.
  • Your nitrogen blanketing sketch is overly simplified and doesn’t give a full definition of how the system works.  That’s why you are confused and don’t understand it.  Download the workbook on nitrogen blanketing in our website and study the explanations I give for nitrogen blanketing and how it is controlled and operated.
  • Again a common sense item: when you pump fluid out of storage tank that is sealed or devoid of a source of positive pressure, you will generate a partial vacuum in your tank’s vapor space.  Everyone should know and understand this.  You cannot tolerate a partial vacuum in a low pressure storage tank without the danger of collapsing the entire structure - and its contents!  That’s why you apply a conservation vent - a relief device that opens to relieve a buildup of internal pressure and also opens to allow atmospheric air to enter the tank when there is a partial vacuum produced inside the tank.
  • A nitrogen blanket works as explained in my workbook: nitrogen is maintained in the tank’s vapor space with a slight pressure (5-15 inches of water column is normal) by a control valve that feeds the tank’s vapor space on pressure demand (as when the fluid is being pumped out).  When the tank receives more stored fluid subsequently, the vapor space pressure increases (since the amount of nitrogen previously introduced is compressed by the rising liquid level).  The conservation vent vents excess nitrogen to the atmosphere to prevent an over pressure.  The nitrogen control valve should fail closed and if it fails to open on the next fluid pump-out, the conservation vent opens to the atmosphere to allow air to break a partial vacuum in the tank.
  • Storage tanks are positively grounded to prevent the accumulation of static electricity - especially when storing flammable fluids.  Explanations for static electricity can be found in your electrical engineering courses or texts - or in the internet.  Wikipedia states: “A static electric charge can be created whenever two surfaces contact and separate, and at least one of the surfaces has a high resistance to electric current (and is therefore an electrical insulator)”.  You should have covered this in your engineering curriculum.

This post is already very long and I hope you have the answers you seek.  If you don’t have basic engineering courses or training, please state so and we can recommend study material.

#117418 Chemical Engineering Plant Cost Index Cepci Of 2016 And 2017 ?

Posted by breizh on 19 February 2019 - 04:03 AM

hi ,

October 2018 :616.3  (final)

November 2018 : 616.4  (preliminary)


good luck


Attached Files

#117410 Solubility Of Hydrogen Sulfide In Petroleum

Posted by PingPong on 18 February 2019 - 04:06 AM

You don't need to do complicated VLE calculations.


A value for total absolute pressure P is required but normally that is known.

But even if it is not known you can simply assume a value for P to determine H.


For example, using the graph in GPSA EDB, the K-value for H2S in hydrocarbons is:

K = 32  at P =   1 bar & 38 oC

K = 3.2 at P = 10 bar & 38 oC


So at 1 bar Henry constant H = 32 * 1 = 32 bar at 38 oC

and at 10 bar Henry constant H = 3.2 * 10 = 32 bar at 38 oC


It makes no difference what P is because K is inversely proportional to P as long as P is not too high (see graph).

In other words: only at very high pressures H is dependent on P.

#116960 Positive Displacement Pump Curve

Posted by Art Montemayor on 01 January 2019 - 03:46 PM



Just as Latex and Fallah state: Although you don't tell us the TYPE of positive displacement pump you are using (a piston pump will have essentially no pump curve; it's displacement is constant if both valves work), the pump's volumetric efficiency will increase as the viscosity increases.  Rotary type pumps depend on internal clearances (pistons don't) in delivering a specified liquid volume per time.  As the viscosity increases, the pump increases its effectiveness due to the thicker fluid.  So, a rotary pump's pump curve will be different for different viscosities.



Happy New Year to all our members and a special salute and recognition to our good Breton friend, BREIZH, who has announced his retirement.  I hope he persists in joining us here on the Forums and I like his latest personal photo  ........ although, like me, he seems to be losing a few hairs.


My personal well wishes go out to all our members and contributors.  May this year be one of happiness and prosperity to all.

#115602 Heat Exchangers, Zone Analysis In Excel With Prode

Posted by PaoloPemi on 20 August 2018 - 09:53 AM

there was a Excel page showing how to calculate properties in different zones I attach a copy, you can examine the VBA code for details,


Prode Properties can export flows or you can calculate from (molar) phase fractions and molar weights of different fractions, see this VBA example


PF = StrLf(Stream)
If (PF > 0.000001) Then ' Liquid present ?
            mw = StrLMw(Stream)
            Cells(rpt + I, 6) = W * PF * mw / mwm ' Liquid Flow


and so on...


you can calculate mixture properties (density, viscosity, thermal conductivity etc.) in different ways,

Prode Properties exposes methods StrGD, StrLD etc. (there are about 300 methods...)

in this Excel VBA example the procedure calculates vapor properties as


            Cells(rpt + I, 14) = StrGMw(Stream)
            Cells(rpt + I, 15) = StrGCp(Stream)
            Cells(rpt + I, 16) = StrZv(Stream)
            Cells(rpt + I, 17) = StrGD(Stream)
            Cells(rpt + I, 18) = StrGV(Stream)
            Cells(rpt + I, 19) = StrGC(Stream)


of course different variants are possible (many methods available),


you can solve many different Flash Operations with Prode Properties, in this case (heat exchanger simulation) the procedure solves a operation with specified P and H but different alternatives are possible



Attached File  htcprops.xls   176.5KB   42 downloads

#111399 Steam To Carbon Ratio

Posted by Flc on 03 October 2017 - 03:38 PM



In syngas plants (ammonia, hydrogen, methanol, etc.) the concepts are different. Steam to dry gas ratio (usually abbreviated as S/DG) is the ratio between molar flow rate of steam and gas, so it's steam flow rate divided dry gas flow rate. This ratio is use frequently at the inlet of shift reactors (HTS, high temperature shift, and LTS, low temperature shift), in particular to evaluate of the flow fed has enough steam as to prevent iron carbide formation in iron-based HTS catalysts.


Steam to carbon ratio is usually used to evaluate the amount of steam at the inlet of a steam reformer, and is the ratio between the steam and the carbon, in mole basis. Consider that C2H6 counts as 2 carbons, C3H8 as 3, etc. E.g. if you have a stream consisting of a mixture of 3000 mol/h of steam, 500 mol/h of C1, and 200 mol/h of C2, ethane counts twice as much (2 carbon moles), so in this case it would be 3000/(500+200*2) = 3.33. In this same case, the S/DG ratio would be simply (3000/700) = 4.28 (though in practice no HTS reactor operates with such a high value).


Theoretically speaking, in the case of a stream consisting of just steam and methane, S/DG and S/C ratio would be the same. In the case of a stream with only steam, methane, and some nitrogen, the S/DG ratio would differ from the S/C ratio. There are some other ratios used, such as the S/C ratio just for hydrocarbons (so you don't consider inorganic compounds such as CO or CO2) or the S/HCC ratio (you just consider HC C2+).


Hope it was clear enough :)


Best regards

#107463 Design Of Distillation Column

Posted by Art Montemayor on 23 January 2017 - 11:57 AM



To learn how to process design a distillation column you can do a variety of things:


  • You can take a first year chemical engineering Unit Operations course in a university that offers such a study;
  • You can purchase and study a book on the subject;  some books are:
    Douglas, James M., Conceptual Design of Chemical Processes, McGraw-Hill, 1988, pp. 453-457.
    Kister, Henry Z., Distillation Design, McGraw-Hill, 1992, pp. 275-282.
    Luyben, William L., "Introduction" in Practical Distillation Control (W.L. Luyben, ed.), Van Nostrand Reinhold, 1992, pp. 10-11.
    McCabe, W.L., J.C. Smith, P. Harriott, Unit Operations of Chemical Engineering, 5th Edition, McGraw-Hill, 1993, pp. 560-568.
    Seader, J.D. and Ernest J. Henley, Separation Process Principles, John Wiley, 1998, pp. 305-312.
  • You can study the material found in many web sites on the internet.  One such site is Dr. Randel Price's (http://facstaff.cbu.edu/rprice/) and a sample of his lecture notes is attached.


Attached File  7-Distillation - Principles.docx   41.13KB   125 downloads

Attached File  8-Distillation II - Modeling.docx   43.81KB   97 downloads

Attached File  9-Distillation III - Operating Equations.docx   51.76KB   93 downloads

Attached File  10-Distillation IV - Calculations.docx   65.62KB   122 downloads

Attached File  11-Distillation V - Ethalpy Balances.docx   39.63KB   86 downloads

Attached File  12-Distillation VI - Enthalpy Concentration Methods.docx   63.35KB   77 downloads

Attached File  13-Distillation VII - Equipment & Column Sizing.docx   56.11KB   121 downloads

Attached File  14-Batch Distillation.docx   45.86KB   84 downloads

#120250 Staggered Set Pressures Of Relief Valves (Column And Reflux Drum)

Posted by Sharma Varun on 27 January 2020 - 11:58 PM

Normally in cases of blocked outlet at column bottoms there is sufficient hold up volume available in the column bottom sump providing operator with sufficient time to act before the relief occurs. Generally liquid filling scenario can at the max dislodge the column internals and entire column being filled is very rare, however same can’t be ignored. Please see at what rate the column is being fed and calculate the time required to fill the column completely, if the time is sufficient you can take credit of level alarms on the column to manually trip the pumps. Column pressure and temperature profile will also indicate the same. If found credible, instead of sizing the PSV and thus the entire flare header for this liquid relief case, HIPPS mechanism with 2oo3 level trip of charge pump can be considered.


Having said that, if you decide not to put the HIPPS or consider the operator intervention, Column overfilling scenario load should relief from column overhead PSV only and not the reflux drum PSV. Your configuration tells me the condenser is total condenser so please check the relief rate w.r.t. condenser outlet. Please note that these multiple valves are provided for dedicated system, they may operate together but there purpose is different.


Coming back to your question overhead drum is generally designed for column top design pressure + static head. Thus safety valve on overhead drum is set at higher set pressure than the column overhead PSV. In short 13.8 barg & 15 barg seems logical to me. 

#114060 Jt Valve In Cryogenic System

Posted by Art Montemayor on 17 April 2018 - 11:16 AM

Syed saqib ahmed:


As usual, Shorty gives an excellent response to your query.

Because this is the Student Forum, we strive to guide and advice students on their studies - rather than their experiences.  For that reason, I would only add for your benefit - as well as for all other students reading this - the following tips, experience, and advice:

  • Return to your basic Thermodynamic studies - whether they be Physical Chemistry, Chemical Engineering Thermo, or other Thermo course you might have or have had and re-read and study again what is discussed in the Thermo theory: Messrs. Joule and Thomson did their studies and work on GASES and not liquids.  The basic Joule-Thomson theory is based on the free, adiabatic expansion of gases and the results generated were on gases.  You are seeking to link the J-T effect with the free expansion of liquids.  That doesn’t work.  It involves another field of study - perhaps linked to J-T, but not the J-T effect.
  • The free, adiabatic expansion of liquids is the basic and primary effect employed in almost all common refrigeration cycles.  This is what drives such refrigeration processes such as ammonia, ethane, propane, ethylene, air, CO2, and all other common refrigerants.  This process may play an important role in your future engineering career and that is why it is important to know the basics and the differences.
  • As Shorty explains, not all gases (including some liquids) cool when expanded freely and adiabatically.  Some well known exceptions are Hydrogen, Helium, and Neon.  Hydrogen gas, especially, heats up and this has been an important experience for me when out in the industrial field.  It is now well known that persons should not get close to high pressure hydrogen piping connections or fittings when out in the field during the daytime.  Any high pressure hydrogen gas leaks will heat up and because of the generated higher temperature and the friction caused, can ignite and cause a bright, almost invisible flame that is not visible in daylight.  I have seen this happen - but only at night time, when the bright, luminous flame appears.  This flame could be a serious hazard during the daytime for anyone passing by.  This, for me, proved the results of Joule and Thomson.
  • In studying your Thermo, note that even gaseous Helium can be liquefied using the J-T effect.  However, it must be below its inversion temperature prior to the free expansion.

#113852 References On Process Diagnosis And Troubleshooting

Posted by Napo on 01 April 2018 - 10:22 AM



Some books are:


- Problem Solving for Process Operators ans Specialist, by J. Bonem (Wiley 2011)

- Process Engineering Problem Solving by J. Bonem (Wiley, 2008)

- Process Plant Design and Operation, by D. Scott and F. Crawley (ICheme, 1994)

- Maintenance of Process Plant, by A. Townsend (IChemE, 1992).



#110289 Calculo Presion Tanque Glp - Calculate Lpg Tank Pressure

Posted by Art Montemayor on 30 June 2017 - 12:43 PM



Igual como nuestro amigo Talvi, yo considero este tema como uno de mayor importancia para todo ingeniero que trabaja o trata con GLPs.  El hecho que GLP es una mezcla de varios gases de hidrocarburos que existen en el estado licuado bajo presión y a temperaturas ambientales significa que este producto licuado esta en condición de saturación.


Identificar la presión de vapor que le corresponde a un gas licuado compuesto de solo un compuesto no es gran cosa.  La literatura y la teoría identifica este procedimiento en forma simple y con tablas de la presión de vapor a varias temperaturas.  No hay ningún problema.  Lamentablemente lo que los libros sobre la teoría no explican es que en la vida real - lo que nos concierne a nosotros los ingenieros - ¡jamás y nunca se va encontrar uno con un liquido 100% puro!  Por lo tanto es primordialmente importante el poder calcular el efecto de una composición de GLP sobre la presión que un tanque de almacenamiento tiene que sostener.

Como el genio de Talvi ha notado, la clave del calculo es la Ley de Raoult.  Y para aplicarla, se necesita la presion de vapor de cada uno de los compuestos a la temperatura indicada.


Considero que la materia que contiene el libro que te he recomendado es importante porque sus autores son personas que han sido lideres en la industria de GLP y, por lo tanto, han aportado detalles de la industria GLP que se basan en lo práctico y lo mas importante en su almacenamiento y distribución.  Es por eso que me he dedicado a copiar por lo menos uno de sus capítulos, Propiedades de Mezclas de GLP,  aunque aun no lo termino.  Sin embargo, he generado un cálculo de Excel que representa un ejemplo en el libro y que debe de explicarte como se puede calcular la presión de vapor dentro un tanque de GLP cuando se sabe la composición del mismo.  Los datos básicos necesarios para el cálculo se pueden conseguir de tablas sobre los compuestos puros o de databases tal como http://webbook.nist....mistry/fluid/.   El libro es del año 1962, y en ese entonces no había “spread sheets” y trabajábamos con gráficos o tablas de propiedades.


Considero que puedes conseguir los valores de cada uno de los compuestos puros y emplearlos el spreadsheet para hacer tus cálculos.  El ejemplo que empleo en el spread sheet es para una mezcla de GLP almacenada a 70 oF.


Ojala que esto, conjuntamente con la valiosa información de Talvi, te ayude a solucionar tu inquietud.


Attached File  Properties of Butane-Propane Mixtures.docx   29.96KB   67 downloads

Attached File  Calculation of LPG Mixture Vapor Pressure.xlsx   13.42KB   82 downloads

#110256 How To Determine The Heat Transfer Coefficient

Posted by breizh on 28 June 2017 - 06:11 AM

Hi ,

To start with .

hope this is going to help you.


Attached Files