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Mmscfd - Molar Flow & Std. Gas Flow


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#1 eastorca

eastorca

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Posted 29 November 2010 - 01:39 AM

Hello every one.

This is the results I got from Hysys Version 7.2. Please, explaint to me: Why molar flow and Std. Gas Flow have the same unit (MMSCFD) but their values is different?
--------------
Molar Flow = 15.03 MMSCFD
Std. Gas Flow = 15 MMSCFD

Please see the attached file.

Thank you so much

Attached Files

  • Attached File  1.png   35.37KB   70 downloads


#2 Art Montemayor

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Posted 29 November 2010 - 10:40 AM


Eastorca:

The reason you have problems understanding what the HySys program prints out is not because of your failure; it is due basically to a lack of correct and intelligent communicating on the part of the HySys programmers and managers. They are demonstrating that they don’t know what they are dealing with or that they don’t know how to express themselves correctly. They, like you and I, should know the following:

A “molar flow rate = the quantity of moles flowing/unit of time

A “Standard” flow rate (of a gas) = the volumetric quantity of gas measured at a STATED STANDARD condition/unit of time.

A mole of gas IS NOT EQUAL to a volume. This not only erroneous, but confusing and bad engineering. The units of molar volume cannot be volumetric. By self-definition, they must be molar (either kgmoles or lbmoles – but MOLES).

This is outright shabby and inferior engineering and HySys has been getting away with this kind of stuff because most engineers are too forgiving. After 7.2 version attempts, one would suppose that the drones at Hysys would have gotten some idea of what it is to communicate accurately and correctly for what the engineering public is paying them for this product. It is to their shame and embarrassment that this type of garbage is still being carried out. Maybe somebody will finally get this message.

I hope that Hysys is at least defining (once and for all) what their bases are for defining Standard Conditions. It is the least they can do.

Please refer to the attached workbook for my illustrated calculations of your shabby Hysys report. I hope I have succeeded in putting your mind at ease. Now, how to get these truths across to Hysys is another question.

Attached Files



#3 eastorca

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Posted 30 November 2010 - 07:48 PM

Dear Art Montemayor

Thank you for your answer. It's so clear and sufficient. Now, I can kick out my confusing.




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