Compact Flat-Box Adsorbers for Air Separation by PSA Processes

Cylindrical adsorbers are usually used for pressure swing adsorption (PSA) processes. In this study, the flat-box adsorbers which stack together replaced the traditional cylindrical adsorbers. Simulation was performed for separation of air (21% oxygen; 79% nitrogen) in Skarstrom cycle. Instantaneous equilibrium between solid and gas phase with non-isothermal operation were assumed and the bed pressure drop could be neglected. The adsorption isotherms used were extended Langmuir isotherms and 5A zeolite was utilized as adsorbent. In addition, to verify the applicability of the simulation program on the system of air separation with 5A zeolite, the simulation results of the cylindrical adsorbers were compared with the experimental data in literature. The simulation results were in good agreement with experimental data obtained elsewhere, and showed the reliability of this PSA simulation program. The simulation results of flat-box adsorbers and traditional cylindrical adsorbers were compared. The performance of the flat-box adsorbers was similar to that of the traditional cylindrical adsorbers when the heat transfer coefficient between neighboring adsorbers is set at 14.049 J/K-m-s at same purge to feed ratio and product to feed ratio. But the flat-box adsorbers were better than the cylindrical adsorbers in the usage of packing space. The effects of operating variables such as step time, bed length, adsorption pressure, the heat transfer coefficient between neighboring adsorbers were investigated on the performance of PSA.