Biogas Purification Using Cryogenic Packed-Bed Technology

A novel process concept for biogas treatment based on dynamically operated cryogenic packed beds (CPB) has been proposed and studied with numerical simulations. This work describes the CPB concept and investigates the different process steps involved with simulation results. To demonstrate the potential to treat biogas using the proposed process, the performance is compared to vacuum pressure swing adsorption (VPSA) on the basis of several criteria: purity and recovery of the obtained product, bed dimensions, and energy requirements. Simulation results reveal that the purity and recovery of CH 4 are higher for the CPB concept, while also the bed capacity is much higher: the productivity (defined as kg CH 4 h –1 m packing –3 ) is a factor of 8 higher. The recovery is carried out with air and when operated in reversed flow mode, the novel CPB technology requires a 22% lower energy duty (2.9 MJ/kg CH 4 vs 3.7 MJ/kg CH 4 for the VPSA process). Furthermore, simultaneous deep H 2 S removal is possible using the proposed concept, although initial bed temperatures as low as −150 °C are required.