Comparison of radial- and axial-flow rapid pressure swing adsorption processes

Compared to axial-flow rapid pressure swing adsorption (RPSA) processes, radial-flow RPSA processes can have the larger cross section for the same volume of adsorbers. Radial-flow RPSA processes, thus, may have the advantage of a low-pressure drop for the same volumetric flow and a small particle size of the adsorbent can be used for the same pressure drop. After an innovative coordinate transformation, the governing equations of both radial- and axial-flow RPSA processes carry a similar form. Therefore, only a simulation program is needed and is developed to simulate the dynamics of the adsorbers for both systems. The simulation results of an axial-flow RPSA were compared with the experimental data in the literature. For the modeling of radial-flow RPSA processes, the parameter of effective length is equivalent to the length of the packed bed of axial-flow RPSA processes. For the same feed pressure and the same amount of adsorbent, the separation performance of the radial-flow RPSA processes would be better than that of axial-flow RPSA processes if small adsorbent particles and long effective lengths were used. The effects of the particle size of the adsorbent, feed pressure, production rate, and feed direction on the performance of radial-flow RPSA were also explored.