Four beds pressure swing adsorption for hydrogen purification: Case of humid feed and activated carbon beds

The novelty of this manuscript is the study of purification of hydrogen from a mixture of H2/CO2/CH4/CO/N2 saturated in water vapor. Simulations results of fixed bed behavior and of an eight steps PSA process are presented using an activated carbon as adsorbent. Several operating conditions were considered, namely different feed flow rates, humid dry feed and adiabatic nonadiabatic operation. Simulation with single column PSA showed that a 99.9979% purity hydrogen stream could be obtained with a recovery of 71.3% and a productivity of 63.9 molH2lkgadsl day. The simulation of a four columns PSA predicted a decrease in H2 purity to 99.8193% for the same operating conditions, due to the impurities present in the recycled stream ofthe continuous mul- ticolumn process. To increase the hydrogen purity above 99.99%, the feed time was decreased 25%. Thus, the multicolumn simulation predicted a hydrogen recovery, purity, and productivity, respectively, of 62.7%, 99.9992%, and 55.2 molH2Jkgadsl day. © 2009 American Institute of Chemical Engineers.