1 reply to this topic

Hey,

I posted this comment in the Student section as I wasn't sure where to put it. Apologies for any duplicates.

This topic has to do with cryogenic air separation, which is our final year design project in Chemical Engineering. We are separting air that contains N2, O2 and Ar to a purity of 99.9%. In the process we have 6 major units which are 2 Linde Columns, 3 distillation columns and a combustion reactor. The 2 Linde colums (a lower and an upper column) primarily create a high purity N2, the 3 distillation columns help to create high purity O2 and high purity Ar and a combstion reactor (which is before the Ar distillation column). The combustion reactor simply removes and water in the stream by reacting O2 with H2.

We are using the program VMGSim to simulate the design. The first thing that VMGSim prompts you is to decide what property package to use (i.e. the equation of state). The property package can be specified in two ways 1) by specifying 1 thermodynamic model or 2) specifying 1 vapor EOS (advanced model) and 1 thermodynamic model. My first question is what EOS do we use to model a cryogenic process (which requires temperatures as low as 78K and pressures as high as 9atm)? I have read many different models that are used and not sure which is the most accurate (ie. one source specified the vapor EOS being Peng-Robinson and the thermodynamic model being NTRL, while another source only specified the thermodynamic model being BWR (Benedict-Webb-Rubin)).

Any help on deciding what EOS to use, would be much appriciated. As well, if any one has any helpful info on Linde Columns, it would be really helpful towards our design project. If you require any additional information, please let me know

Thanks,

TA

[Padmakar Katre]

Dear,
I hope rather going for this ComThermo option like PR-NRTL you try with PR I hope this will yield good results.
P.S.- VMGSim is a baby of the same parents of Hyprotech Hysys try PR.