Differences between SRK and PR equations
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The SRK equation, used in gas and refining processes, can calculate K values, enthalpy, entropy, gas density, and liquid density (with limitations); it is generally not used for highly non-ideal systems, supports free water, but does not support VLLE. PR equation, main refining process; capable of calculating K value, enthalpy, entropy, and gas density; not suitable for highly non-ideal systems; supports free water, but does not support VLLE. The applicable conditions for both are the same: pressure: 0～5000PSIA, temperature: -460～1200F. Here lies the problem: for low-carbon alkanes with a small amount of hydrogen or no hydrogen at all, which thermodynamic equation should we choose? (Today, when working on the demethanizer, I felt that the SRK equation should be used, but the book used the PR equation; I’m not sure why, so I’m seeking advice from everyone.) This post was last edited by flyinghappyking on 2007-11-27 15:35]
Do you mean the difference between “used in gas and refining processes” and “the main refining process”? I should check the calculation results first; I usually use these two property-based methods for gas separation, and the results differ very little. Some references state that PR is better than SRK. This post was last edited by LTY on 2007-11-27 15:48]
The PR equation should be used, and it can be shown that the applicable conditions for the two equations are similar; however, PR is more suitable for refining systems, especially in gas processing, as its applicable conditions are broader than those of SRK. The information you have access to is not up-to-date, so although the applicable conditions appear the same, they are actually different.