On the modeling of PSA cycles with hysteresis-dependent isotherms

A four-step pressure swing adsorption (PSA) process for air drying on a sil icagel dessicant is considered. The effects of hysteresis in adsorption/des orption equilibrium isotherms and of loading dependence of the effective di ffusion coefficient on the process performance are investigated on a mathem atical model. A. comparative parametric study reveals that for identical op erating conditions, hysteresis can be detrimental to product purity. Multip licity of cyclic steady states is shown to exist as a result of hysteresis. A transient regime invoked by a gradual change in the inlet air humidity i s discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.