Energy transfer in hydrogen separation from syngas using pressure swing adsorption (PSA) process: a thermodynamic model

This paper presents the thermodynamic modeling of a pressure swing adsorption (PSA) unit for hydrogen separation from a syngas mixture, which can be obtained from biomass gasification. Two different types of activated carbon (A-20 and Maxsorb III) have been considered for CO2 adsorption from the gas and the variations in the adsorber bed size and energy transfer have been analyzed at different adsorption pressure, ranging from 2000 to 4000kPa, and at 320K temperature. CaX Zeolite has been utilized for the adsorption of other constituents (N-2 and CH4) in the gas mixture. The bed size decreases while the energy consumption in the process increases with the increase in adsorption pressure. The decrease in bed size is found to be 48%-50%, and the energy consumption increases by 31%-32% over the range of adsorption pressure and for the adsorbent materials considered. Allowing the minor components (N-2 and CH4) with hydrogen (without separating them from the gas) drastically reduces the bed size and energy consumption. This reduction of bed size is found to be around 70% for A-20 and 85% for Maxsorb III, and the decrease in power consumption is around 25% for either of the adsorbents. Maxsorb III has been found to be a better CO2 adsorbent with higher working bed capacity than A-20. The analysis has also been extended to 300K bed temperature for Maxsorb III adsorbent to identify the effect of bed temperature on the adsorption process. At this temperature, a decrease of around 30% in column volume and a hike of 27%-35% in the energy consumption have been observed in the aforesaid adsorption pressure range. Copyright (C) 2016 John Wiley & Sons, Ltd.