Numerical Study of Methane Separation from Biogas by Pressure Swing Adsorption

Pressure Swing Adsorption (PSA) is one of the promising processes for removing carbon dioxide and hydrogen sulfide in biogas streams. However, it is difficult to obtain all the detailed parameters for each step in the PSA process experimentally. Then, a two-bed PSA cycle for the production of biomethane from methane/carbon dioxide/hydrogen sulfide mixtures using commercial adsorbent is analyzed by numerical simulation using Aspen Adsorption® software. The aim of a PSA modeling is to obtain a gas of methane with purity higher than 97%. A parametric study is performed based on three key operating parameters (i.e., (P/F) ratio, adsorption time and vacuum pressure). The sensitivity study concluded that a 2-bed 6-step PSA can produce methane with purity above 97% and a recovery of around 83% in a configuration with adsorption time between 200 and 230 s for P/F ratio of 0.27 and for pressure of 4 bar.