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Critical Properties Of Gas Mixtures

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#1 Guilhermexift


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Posted 09 June 2019 - 09:16 PM



Does anybody know how to estimate the critical temperature and pressure of a gas mixture?



#2 breizh


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Posted 09 June 2019 - 09:35 PM

hi ,


  Sum [mol fraction i * Tci or Pci]



Edited by breizh, 09 June 2019 - 09:49 PM.

#3 oilpmp


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Posted 10 June 2019 - 01:27 AM

I agree with the post of Breizh, I think this is excellent as starting point.


yet, I want to add a word of caution.


The OP did not state what level of accuracy is expected  nor the type of mixture (estimating to 0.5% or 50% error is different "ball game"; and in this field there is wide possibility for error depending on the gas mixture under consideration and the procedure).


For instance the procedure of API Databook for estimating critical temperature of a gas mixture (4B1.1) can deviate from 0.5% on average to absolute deviations in the range of 100deg to 200 deg (!). 

#4 Bobby Strain

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Posted 10 June 2019 - 09:14 AM

You probably should consult your textbooks. And use your favorite search engine.



#5 Chemitofreak


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Posted 11 June 2019 - 12:55 AM

Use software like Aspen, Hysys or Pro II

#6 breizh


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Posted 11 June 2019 - 01:30 AM   Best Answer

Hi ,

To add to my previous answer , I will suggest you to get a copy of : the properties of gases and liquids , chapter five .


Good luck


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Edited by breizh, 11 June 2019 - 01:40 AM.

#7 PingPong


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Posted 12 June 2019 - 10:06 AM

Guilhermexift should first explain for what purpose he needs those critical properties.


It is important to understand that the real Tc and Pc of a mixture are not the same as the pseudocritical Tpc an Ppc


Taking the molar average of the Tc's and Pc's of the components in a mixture yields the pseudocriticals.


The real Tc and Pc of a mixture can only be obtained by producing a phase envelop using a process simulator like Aspen, Hysys or Pro II.

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