Improving the performance of vacuum swing adsorption based CO2 capture under reduced recovery requirements

Abstract

This work discusses the effects of reduced CO2 recovery targets, i.e., <90%, on post-combustion CO2 capture through vacuum swing adsorption. Detailed computational modeling combined with multi-objective optimization is used to study the impact of CO2 recovery on parasitic energy consumption and process productivity. The study is performed for three different CO2 compositions that are representative of flue gas from cement industries, coal-fired and natural gas fired power plants. The influence of the separation agent, the adsorbent, is explored by considering four different materials, namely Zeolite 13X, a metal organic framework UTSA-16, coconut-shell activated carbon and a hypothetical minimum-energy adsorbent. Significant reduction in energy and increase in productivities were noticed when the recovery constraints are relaxed. For instance, in the case of UTSA-16 ≈ a three times increase in productivity can be achieved without increase in parasitic energy if the CO2 recovery can be lowered from 90% to 70%. At low recoveries it is also possible to work at moderate vacuum pressures (0.1 atm), thereby making vacuum swing adsorption processes practically realizable at large-scales.