questions asked outside the forum

[Karen Kietzke, Research Programmer, IECM, CMU]

We sometimes get questions which are not common enough to belong in the FAQ, but which might still be useful to somebody. I will be posting some of those questions and answers here.

[Karen Kietzke, Research Programmer, IECM, CMU]

We received the following question from a user:

I am currently modeling an oxyfuel CCS system in IECM.  When looking at the output of the Air Separation/CCS components, a value is given for the volumetric amount of Nitrogen that is vented after the air separation process (in terms of tons per hour volumetric flow).
Given that cryogenic distillation technology is used to model the air separation unit process, this typically entails compressing/liquefying and separating both nitrogen and oxygen (and possibly Argon) within the air stream that is sucked into the air separation unit.  If this is the case, is the nitrogen that is vented represented in terms of liquid nitrogen or is the liquid nitrogen obtained from the cryogenic distillation process expanded into a gaseous form before atmospheric venting?
Similarly, is either the liquid oxygen from the ASU or the oxidant expanded from a liquid to gaseous form before being combined with the recycled flue gas?

The answer:

Yes, all flow rates shown are gaseous components. Regasification of N2 and O2 is an intrinsic part of the ASU model.