Application of Pressure Swing Adsorption to Impurities Removal

Pressure swing adsorption was applied to carbon dioxide and water removal instead of thermal swing adsorption as a pretreatment of compressed air for a cryogenic air separation plant. Due to use of a two-layer-column method, with zeolite and activated alumina packed in two separate layers, the concentration of carbon dioxide in purified air is decreased from 340 ppm to 1 ppm. The electric power unit for a pressure swing adsorption process was about 85% of that for a thermal swing adsorption process because no refrigerating heater or refrigerator was required. The carbon dioxide concentration of purified air is expressed as C=86SV2 (Pa/Pd) -1.3x-2 where C is the carbon dioxide concentration of purified air, SV is the space velocity of purified air, Pa is the adsorption pressure, Pd is the desorption pressure and x is the purge ratio.