Material balance and energy consumption for CO2 recovery from moist flue gas employing K2CO3-on-activated carbon and its evaluation for practical adaptation

Potassium carbonate supported on an activated carbon has been proposed as an efficient sorbent to recover CO, from moist flue gases. As a characteristic of the present CO2 sorption process, which can be described as K2CO3.1.5H(2)O + CO2 = 2KHCO(3) + 0.5H(2)O, moisture in the feed gases had no influence on the CO2 sorption. By the temperature-swing operation of a fixed-bed, the CO2 recovery was achieved as follows: carbon dioxide in moist flue gases at around 363 K was sorbed by the K2CO3 sorbent, followed by steam flushing at 433 K to release the CO2, and then cooling the sorbent for the next CO2 sorption. In the present study employing a bench-scale apparatus, the material (CO, and H2O) balances, together with those of heat during each step, were measured to elucidate the CO2 sorption/release and the cooling behaviors. To evaluate the practical adaptability of this process, the heat consumption for the CO2 recovery on a commercial-scale was estimated. When compared with that for other processes such as the conventional amine process, it provided a remarkable energy-conservative effect. The cost for the CO2 recovery by K2CO3-on-activated carbon is also discussed.