Abio:
Process Simulators are very good at predicting process designs and conditions. However, one of the worst applications for a process simulator is to use it as a mechanical design tool. They are not intended for this application. Separator and scrubber designs (both process design and mechanical design) are best done on a spread sheet. If you don’t have one, you should develop one – that way, you will understand exactly what parameters are involved and how to apply them.
Serious engineering attempts by using canned programs is fine – if you know exactly what you are doing, what is involved, and how to interpret the output. Otherwise, I wouldn’t trust the results generated by an engineer who doesn’t know what equations and algorithms are involved and how, when, and where he can apply them.