Performance exploration of temperature swing adsorption technology for carbon dioxide capture

Adsorption technology is recognised to be a promising CO2 capture method due to its desirable characteristics e.g. reusable nature of adsorbents, low capital investment and easy automatic operation. To further improve thermal performance, internal heat recovery is adopted for adsorption CO2 capture through analogy with adsorption refrigeration. Based on carbon pump theory, thermal performance of 4-step temperature swing adsorption (TSA) processes is analysed at various adsorption/desorption temperatures and pressures. Exergy efficiency of adsorption CO2 capture with and without heat recovery will be evaluated and compared by using experimental adsorption characteristics of activated carbon. Metal part and unused percentage of adsorption reactor are defined to further assess their influence on system performance in real application. Results indicate that sensible heat of adsorbents and adsorbed phase account for the major part of heat consumption. For different desorption/adsorption temperatures and pressures, theoretical exergy efficiency of 4-step TSA cycle ranges from 0.022 to 0.221. Heat recovery is conducive to exergy efficiency. Through heat recovery, exergy efficiency could be improved from 54.3% to 84.6% when mass ratio increases from 0 to 8. Similarly, the improvement by using heat recovery is up to 90% in terms of different unused percentages.