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/kgCO2) 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 °C) and the purge flow rate (0.1–0.5 Ndm3 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 gCO2/kgads h and a specific energy consumption of 3.23 MJ/kgCO2, 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.

► We prove our indirect TSA process to be competitive with MEA for CO2 capture.
► The achieved performances are: 95% in purity and 81% in recovery for CO2.
► Energy consumption is 3.2 MJ/kgCO2 and productivity 58 g kgads−1 h−1.
► Leads for improvement: VTSA operation, pre-cooling step inclusion.