INSIGHTS INTO THE DESIGN OF OPTIMAL SEPARATION SYSTEMS USING MEMBRANEPERMEATORS

Using a new robust design model, parametric studies have been performe d to investigate the behaviour of gas separation systems based on memb rane permeators. The existence of a maximum for permeate purity as a f unction of membrane pressure ratio is observed for simple permeators w ithout recycle. It is found that overpurification of the permeate stre am, followed by mixing (a by-pass configuration) may be profitable in cases where membrane area is ex-pensive compared to compression, and p urity requirements are modest. Retentate recycle is found to be detrim ental to product purity and recovery in both retentate and permeate st reams. It is shown that permeate recycle may significantly reduce comp ressor duty, even in cases where recycle is not required to obtain the specified permeate purity.