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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.




#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.


#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   34 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   114 downloads

Attached File  8-Distillation II - Modeling.docx   43.81KB   89 downloads

Attached File  9-Distillation III - Operating Equations.docx   51.76KB   80 downloads

Attached File  10-Distillation IV - Calculations.docx   65.62KB   109 downloads

Attached File  11-Distillation V - Ethalpy Balances.docx   39.63KB   76 downloads

Attached File  12-Distillation VI - Enthalpy Concentration Methods.docx   63.35KB   69 downloads

Attached File  13-Distillation VII - Equipment & Column Sizing.docx   56.11KB   107 downloads

Attached File  14-Batch Distillation.docx   45.86KB   76 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



#116663 Column Overhead Air Cooled Condenser Outlet Piping Hammering

Posted by gegio1960 on 03 December 2018 - 02:12 AM

from a process point of view, the system is highly non-symmetrical and this is not acceptable.

each couple of the outlet lines should be symmetrically joined in a common sub-header and this step shall be repeated down to a single line.

all the pipe segments shall be carefully sized following the rules of the 2-phase flow.

a larger sub-header shall be provided where the symmetry can't be exactly respected (eg if you start with 12 outlet lines, you go symmetrically to 6 and then to 3 but at this point you shall provide the larger subheader to mitigate the loss of symmetry).

the non symmetrical pipes will provide preferential ways to the the fluid and so high velocities and the consequent vibrations in the overloaded sections.

moreover, the operating conditions/performances shall be compared to the design. how much flow? which is the vapour fraction at the cooler outlet?

less generic answers could be obtained with all the details available.

the 2nd drawing you provided is not an isometric and does not show the equalization like. anyway, the outlet from the header seems not in accordance with the good engineering rules of 2-phase flow (ie absence of sharp deviations). 

good luck!

#116429 What Is Value Engineering

Posted by Bobby Strain on 10 November 2018 - 11:14 PM

I would, as a client,  evaluate licensors and design contractors thoroughly and avoid any such thing as Value Engineering. Things that are a part of VE come from an assembled group of mostly dummies. But, clients slough through because VE has been dictated by someone in the client's organization. I't kind of like a HAZOP, only less useful. Sometimes harmful. Good luck.



#115608 Vapor-Liquid Equilibrium Curve Using Partial Pressures

Posted by Nikolai T on 21 August 2018 - 02:27 AM

Dear participants,


Please, look at modified file. Are there suggestions about the solution?






Attached Files

#111748 P&id Number Stenciling On Process Piping

Posted by fallah on 28 October 2017 - 04:53 AM

From a process safety perspective, how important it is to have the piping tag number stencilled on the piping external surface in a process plant?




I think from "piping tag number" you actually mean "line number". If so, it could be useful for line up; but cannot be so sustained and will be removed due to maintenance activities and ambient conditions.  

#111737 Temperature Changing During Mixing 2 Streams

Posted by Bobby Strain on 26 October 2017 - 06:35 PM

But I think the real system will exhibit a lower temperature after mixing. So, be careful where you get advice. Best to find some actual data for confirmation.



#111372 What Is The Benefit Of Holdup And Surge Volume In Separator Design

Posted by fallah on 01 October 2017 - 01:21 PM

i'm read about separator design and some problem like slug flow but i cant found any information about benefit surge and holdup volume in design


They are, in fact, the separator design requirements not its benefits...!

#111559 Molecular Weight Effect On Centrifugal Compressor

Posted by breizh on 14 October 2017 - 02:57 AM

hi ,

some literature to support your work .

Hope this helps



Attached Files