1 reply to this topic

[chem2013]

Dear All,

 

I have to estimate distribution of H2,C1,C2,C3,C4,C5,H2S in cooling water system as a mixed gas stream. My CW system is operating at 2.5 barg and 47 degC.

 

Water and H2S are polar component. Therefore, EOS model would not work here like peng robinson. Since this gas mixture would operate below its critical temperature, activity model should be used for calculating solubility.

 

I just want to know whether

(1) Henry's law equation specified with activity coefficient model would be most appropriate for this total system ?

(2) Sour peng robinson could be used or not since H2S is there? It looks to me this model is not a pure EOS model and has some additional feature.

 

Please advise on these points.

 

Regards.

 

 

[RockDock]

Indeed, H2O and H2S are polar. However, you need to look at the degree of polarity. Polar property packages are generally created for very polar components, like methanol.

 

In general, software companies don't use just a straight Peng-Robinson package. They modify it according to the common processes it is used for. Hysys, for example, has it modified for lighter hydrocarbon separation. They may even account for water polarity in the phase behavior. I would expect that. However, I do not expect Hysys to accurately model the H2S. For that, I would recommend ProMax. Also, ProMax has a polar property package you can use to check if there are any differences for your particular process. I've seen data that shows Hysys with over 200% error in calculating the phase behavior for some hydrocarbon/water/H2S mixtures. John Campbell wrote an article on that.