6 replies to this topic

[Guilhermexift]

Hello,

 

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

 

 

[breizh]

hi ,

 

  Sum [mol fraction i * Tci or Pci]

 

Breizh

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

[oilpmp]

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 (!). 

[Bobby Strain]

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

 

Bobby

[Chemitofreak]

Use software like Aspen, Hysys or Pro II

[breizh]

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

Breizh

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

[PingPong]

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

 

It is important to understand that the real T_c and P_c of a mixture are not the same as the pseudocritical T_pc an P_pc

 

Taking the molar average of the T_c's and P_c's of the components in a mixture yields the pseudocriticals.

 

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