Simulation of the Cyclic Operation of a PSA-based SEWGS Process for Hydrogen Production with CO2 Capture

Abstract

A dynamic one-dimensional homogeneous model for multiple bed Sorption Enhanced Water Gas Shift (SEWGS) system has been developed in this work. The SEWGS system under consideration is based on a Pressure Swing Adsorption (PSA) process which operates in a cyclic manner. During the reaction/adsorption step, CO2 produced by Water Gas Shift (WGS) reaction is simultaneously adsorbed on a highly CO2-selective solid adsorbent and removed from the gas phase, enhancing the WGS reaction toward higher reaction conversion and hydrogen production. The periodic adsorption and desorption of CO2 is induced by a pressure swing cycle, and the cyclic capacity can be amplified by purging with steam. Simulation results enable tracking the operation of the system over sequence of steps. As it is expected, high levels of CO conversion and CO2 capture ratio are achieved by enhancing the equilibrium reaction of WGS with adsorbents. Moreover there is no need to reheat the hydrogen product before it enters the gas turbine due to operability of SEWGS system at high temperature of approximately 400°C. Hydrogen production undergoes repeating fluctuations over cycle time which is associated with using part of the H2 product for repressurization step.