Cycle Synthesis and Optimization of a VSA Process for Postcombustion CO2 Capture

A systematic analysis of several vacuum swing adsorption (VSA) cycles with Zeochem zeolite 13X as the adsorbent to capture CO2 from dry, flue gas containing 15% CO2 in N-2 is reported. Full optimization of the analyzed VSA cycles using genetic algorithm has been performed to obtain purity-recovery and energy-productivity Pareto fronts. These cycles are assessed for their ability to produce high-purity CO2 at high recovery. Configurations satisfying 90% purity-recovery constraints are ranked according to their energy-productivity Pareto fronts. It is shown that a 4-step VSA cycle with light product pressurization gives the minimum energy penalty of 131 kWh/tonne CO2 captured at a productivity of 0.57 mol CO2/m(3) adsorbent/s. The minimum energy consumption required to achieve 95 and 97% purities, both at 90% recoveries, are 154 and 186 kWh/tonne CO2 captured, respectively. For the proposed cycle, it is shown that significant increase in productivity can be achieved with a marginal increase in energy consumption. (c) 2013 American Institute of Chemical Engineers AIChE J, 59: 4735-4748, 2013