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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   48 downloads

#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   36 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   115 downloads

Attached File  8-Distillation II - Modeling.docx   43.81KB   90 downloads

Attached File  9-Distillation III - Operating Equations.docx   51.76KB   81 downloads

Attached File  10-Distillation IV - Calculations.docx   65.62KB   110 downloads

Attached File  11-Distillation V - Ethalpy Balances.docx   39.63KB   79 downloads

Attached File  12-Distillation VI - Enthalpy Concentration Methods.docx   63.35KB   70 downloads

Attached File  13-Distillation VII - Equipment & Column Sizing.docx   56.11KB   108 downloads

Attached File  14-Batch Distillation.docx   45.86KB   77 downloads

#118286 Hydraulic Calculation For Jet Fuel Pipeline

Posted by katmar on 02 May 2019 - 03:16 AM

It is not possible to say whether the comment you received is valid or not without knowing further information.


If the specification for the pipeline was given in volumetric terms (eg litre per hour) then it is true that a higher density will result in a higher pressure drop.  However, if the specification was given in mass terms (eg kg per hour) then the higher density would result in a lower pressure drop.


If the spec is given in volumetric terms then changing the density has no impact on the velocity but it does affect the Reynolds number and therefore the friction factor.  When working in mass terms changing the density has a direct effect on the velocity but no effect on the Reynolds number or friction factor.

#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

#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).



#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

#111530 Surge Phenomena

Posted by fallah on 11 October 2017 - 02:27 PM




The water hammer or surge phenomena in a pump is happened mostly due to sudden fluid velocity change (pump trip or sudden discharge valve closing) from the value corresponding to normal flow rate toward zero....The case will be the same for compressors too, but with much lower intensity due to handling the gas rather than liquid...


But in a centrifugal compressor as the discharge valve is closed or demand is so reduced, the differential head across the compressor will increase which pushes the compressor goes back along the performance curve same as a pump.  When the differential pressure gets too large while forward flow is continued, contrary to a pump, the flow will reverse through the compressor, which reduces the pressure at the outlet to compensate the pressure reduction at the inlet.  At the moment, the differential pressure is low enough for forward flow to be rebuilt.  The process repeats again and again if no protection is provided as anti surge which might lead to catastrophic failure of the compressor.

#110118 Calculo Presion Tanque Glp - Calculate Lpg Tank Pressure

Posted by Art Montemayor on 17 June 2017 - 05:02 PM



Aun no me has contestado mis preguntas.  No sé que ingeniería estudias, en que año estas, o cuantos cursos en ingeniería has tomado (especialmente aquellos sobre equilibrio de fases).  Sin saber esos particulares, no puedo ayudarte en lo que necesitas.  Por lo tanto voy a dedicar algunas palabras generales a lo que yo identifico como información importante que hace falta en cursos universitarios de ingeniería:

  • Lamentablemente, la mayoría de estudios universitarios que tratan con la ciencia pura solo se dedican a los compuestos o elementos PUROSLa realidad del hecho es que en la vida real jamás vas a encontrar compuestos o elementos químicos que están en el estado puro.  Somos nosotros los ingenieros que tenemos que enfrontarnos con los compuestos mixtos en la vida real.  Y para poder trabajar con dichos compuestos, tenemos que saber y dominar equilibrio de fases.  Esto incluye estudios termodinámicos que incluyen temas como los diagramas termodinámicos tipo “Mollier” o de temperatura-entropía.
  • Un mezcla de hidrocarburos - como lo es el GLP - es una mezcla de gases (a condiciones ambientales) que se almacena en el estado LICUADO y saturado.  Esto se hace así porque el estado licuado contiene más masa unitaria que el estado gaseoso.  Esto es una decisión practica y de sentido común que lo hacemos los ingenieros que somos prácticos.  Un metro cubico de capacidad simplemente contiene más masa en el estado licuado que en el estado gaseoso - y se necesita menos espesor de tanque, como veras más abajo.
  • Sucede que una mezcla de butano+propano licuada a condiciones saturadas va generar una presión de vapor que es menos que 200 psig cuando esta a temperaturas ambientales (esto lo vez en la tabla que adjunte a mi previo post).
  • Ya que sabemos que no vamos a necesitar más de 200 psig, la industria de fabricacion de tanques a presión emplea planchas de acero “standard” (lo que existe en plaza) para fabricar este tipo de tanque y se encuentra que estos tanque pueden aguantar hasta 250-300 psig MAWP (Maximum Allowable Working Pressure = presión máxima de trabajo), lo que permite instalar una válvula de seguridad fijada a esas presiones.
  • Por lo anterior, el resultado es que estos tanques son mas que adecuados en forma de seguridad y no hay por qué temer que existen problemas de sobre-presión.
  • No olvides: el GLP existe dentro el tanque en la forma SATURADA.  Su presión de vapor varia según la temperatura que existe en el ambiente.  También se podría almacenarse el GLP a temperaturas mucho menores - lo que resultaría en tanques con un espesor menos en sus planchas de acero.  Pero ese tipo de diseño requiere aleaciones de acero que son más caras y además el tanque tuviese que ser aislado - detalles que resultan en un tanque que no es practico ni económico.  Es por eso que la industria siempre emplea tanque de acero sin aislamiento y de planchas de acero que están en plaza, son económicas, y de un espesor aceptable debido a la relativamente baja presión de vapor que rinde el GLP a temperaturas ambientales.


Todos estos factores sobre los cuales hablo no los vas a oír en un salón de clase en una universidad.  Esto no sucede porque tus profesores son ignorantes sobre la ingeniería.  Es cosa que los profesores no tienen la experiencia práctica en haber trabajado en la industria porque habrán tenido que pasar sus años cualificando para sus posiciones en facultades.  Por esa razón es que sigo recalcando en cada oportunidad que tengo con estudiantes de ingeniería que deberían usar su sentido común e ingenio en toda oportunidad que tengan con respeto a problemas de ingeniería.  Por eso es que nos llaman “ingenieros” - porque solucionamos problemas empleando el ingenio.


Ojala esto te ayude en orientarte mejor en futuros problemas.


#109716 Phosphate Dosing Point In High Pressure Boiler

Posted by Mahdi1980 on 25 May 2017 - 03:33 AM



You may find the required information through the enclosed file.



Attached Files

#112409 Calculation Of Required Solvent Rate For Chemical Absorption

Posted by Pilesar on 12 December 2017 - 02:22 PM

You might start with the 'SO2 and Acid Gas Controls' EPA paper https://www3.epa.gov...r1/cs5-2ch1.pdf for a nice overview.