Adsorption dynamics of a layered bed PSA for H₂ recovery from coke oven gas

Abstract

Abstract The adsorption dynamics of a layered bed packed with activated carbon and zeolite 5A were studied experimentally and theoretically through breakthrough experiments and two‐bed pressure swing adsorption (PSA) processes by using coke oven gas (56.4 vol. % H 2 ; 26.6 vol. % CH 4 ; 8.4 vol. % CO; 5.5 vol. % N 2 ; and 3.1 vol. % CO 2 ). The results of breakthrough curves of a layered bed showed an intermediate behavior of those of zeolite‐5A bed and activated carbon bed, because each concentration front propagates with its own wavefront velocity in each layer by a different adsorption equilibrium. Since a fast and dispersed mass‐transfer zone of CO in the zeolite layer of a layered bed leads to a long leading front of the N 2 wavefront, controlling the leading wavefront of the N 2 plays a very important role in obtaining a high‐purity product and in determining the optimum carbon ratio of a PSA process for H 2 recovery from cokeoven gas. The layered bed PSA process was simulated in a simplified form of two single‐adsorbent beds linked in series. The dynamic model incorporating mass, energy, and momentum balances agreed well with the experimental data. Concentration profiles inside the adsorption bed were also investigated.