Use of oxygen enriched stream produced from air spans from classical chemical engineering to biological and medical applications. Oxygen concentration from air by Pressure Swing Adsorption (PSA) enjoys a good market share for small to medium scale operations. Portability of the unit is an important consideration in many medical applications. The smallest oxygen concentrator currently available for personal use that delivers 5 L/min has the size of a small suitcase and weighs about 10 kg. Further reduction in size is an area of on-going interest and has the potential to significantly improve the quality of life of active people needing oxygen therapy.

One idea that is being toyed lately is the use of a short bed of nitrogen selective adsorbent operated on a high frequency PSA cycle. A simulation study investigating the feasibility of such an idea will be the central theme of the talk. Departure from equilibrium and plug flow approximations in a high frequency PSA operation in a small bed will be assessed. Solutions of the model equations using FEMLAB as well as our own FORTRAN codes based on the method of orthogonal collocation will be compared and the experience with FEMLAB as a potential tool for PSA simulation will be shared. The validity of the Linear Driving Force (LDF) approximation for capturing adsorbate transport in the bidispersed adsorbent pores will also be evaluated by comparing with a more realistic pore model solution that assumes equilibrium in the micropores and allows for molecular diffusion in the macropores.