Ask about the selection of thermodynamic equations for ASPEN
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I used PROII before; I’ve only been working with ASPEN for a short time now, and I find that the most complex aspect of this software is the selection of thermodynamic methods. There is such a stream with a composition of H2O\O2\CO2, at 25 MPa and 370°C, where water accounts for 90% (vt) ； At this point, it is still in a two-phase state of gas and liquid; this stream is then fed into a gas-liquid separation tank (the pressure in the tank remains constant, and the heat load is set to 0). The question is: 1. What thermodynamic approach should be chosen for this stream before it enters the buffer tank? 2. What is then the thermodynamic approach for buffer tanks? 3. When I use NRTL for ASPEN and SRK for PROII, the results are not very different. If ASPEN also uses SRK, the results differ greatly. I found that when using SRK and NRTL, the results can differ significantly. Confused... If there are any good documents on thermodynamic methodology*, please let me know as well. Thank you!
In NRTL, CO2 and O2 are generally treated as Henry components, while SRK uses an equation of state to calculate CO2 and O2; it is normal for the results to differ
For this high-temperature and high-pressure condition, which equation should I choose?
If, under high temperature and pressure, a substance is mostly in gaseous state, it’s still better to use a state equation
Use SRK....... ....