Numerical parametric study on CO2 capture by indirect thermal swing adsorption

Post-combustion CO2 capture remains one of the most-challenging issue to lower CO2 emissions of existing power plants or heavy industry installations because of strong economy and energy efficiency aspects. The major issue comes from CO2 dilution (4% for NGCC and 14% for PC) and the high flow rates to be treated. Furthermore, CO2 purity has to be higher than 95% with recovery at 90%, to match the transportation/injection requirements. The MEA absorption process remains the reference today but its energy consumption (about 3 MJ/kg(CO2)) and the amine consumption are still challenging drawbacks. The interest of CO2 capture by indirect TSA (Temperature Swing Adsorption) was demonstrated experimentally in a previous work. The aim of this paper is to present the results of a numerical parametric study. Two main parameters are explored: the desorption temperature (100-200 degrees C) and the purge flow rate (0.1-0.5 Ndm(3) min(-1)). Four performance indicators are evaluated: CO2 purity, recovery, productivity and specific energy consumption. Results show that purity above 95% can be achieved. Keeping the 95% target, it is possible to achieve recovery at 81% with productivity at 57.7 g(CO2)/kg(ads) h and a specific energy consumption of 3.23 MJ/kg(CO2), which is less than for the reference MEA process. Comparison with other adsorption processes exhibits that this process has good potential especially since some improvements are still expected from further research. (C) 2011 Elsevier Ltd. All rights reserved.