Design of a Pressure Swing Adsorption Process for Postcombustion CO2 Capture

The adsorption processes for postcombustion CO2 capture are usually based on a temperature or vacuum swing (TSA or VSA). In the present contribution an alternative concept is presented, which is based on the regeneration of the solid sorbent (an immobilized amine) by a purge gas, low pressure vapor, under almost isothermal conditions. Because of the close to isothermal operation, the process consumes significantly less thermal and mechanical energy than conventional TSA and VSA processes, respectively. We present a rough design of such an isothermal concentration swing process based on a simplified, analytical model of a 2-step PSA (pressure swing adsorption) process. The analytical model allows a definition of the range of operating conditions that lead to the best compromise between energy consumption and productivity (size and number of the adsorbers). Moreover, it is possible to define the equilibrium and mass transfer properties of the ideal solid sorbent. The feasibility of the concentration swing process was finally validated by numerical simulations of a full PSA cycle under adiabatic conditions.