(505c) A Two-Step Pulsed Pressure Swing Adsorption Based Oxygen Concentrator

A two-step pulsed pressure-swing adsorption process (PPSA) has been modeled to assess the extent to which an oxygen concentrator might be miniaturized for medical applications. The process consists of a single bed of packed adsorbent particles that is alternately pressurized and depressurized at the feed end. An enriched oxygen product is withdrawn at ambient pressure from the product end when the bed is pressurized at the feed end. The product end remains closed during depressurization. The describing equations were solved using COMSOL® multiphysics software. The effect on the performance of the adsorption time, desorption time, bed length, particle diameter and imposed pressure drop across the bed were investigated. An interesting novel result is that for a chosen particle size, bed length and applied pressure drop, there is an optimum combination of adsorption and desorption times that maximizes the product purity. The results suggest that there is a reasonably wide operating window wherein the product oxygen purity is consistently greater than 80% for both 5A and partially Ag-exchanged Li-substituted 13X zeolite adsorbents. At a given product flow rate within this operating window, the extent of miniaturization is limited by the (maximum) cycling frequency that is practically achievable. Sizing of an oxygen concentrator for personal medical applications will also be discussed.