SIMILARITY SOLUTIONS FOR PRESSURIZATION AND DEPRESSURISATION WITH A 2-COMPONENT GAS IN AN ADSORBING BED

This paper reports a mathematical analysis performed in support of an experimental and computational study of rapid pressure swing adsorption applied to the separation of oxygen and nitrogen from air. Similarity solutions are obtained for the pressurisation and depressurisation of a semi-infinite adsorbent bed which preferentially adsorbs one component of a two-component gas, under the following conditions: gas flow in the bed is governed by Darcy's law, the adsorption process is isothermal and at equilibrium, the isotherms are linear, and there is no axial dispersion. When the bed is pressurised, there is a shock across which the component partial pressures are discontinuous, whereas the total pressure remains continuous. When the bed is depressurised, there is no shock. Solutions are given for air over zeolite 5A. The case of identical isotherms is also discussed.