Recovery of CO2 from moist gases by fixed-bed operations over K2CO3-on-carbon in a bench-scale plant

Chemical absorption by aqueous solution of potassium carbonate is an excellent method for recovering CO2 from flue gases, but it consumes a sizable amount of primary energy for heating a large amount of solvent water to recover the entrapped CO2. Thus, in an attempt to reduce energy consumption, potassium carbonate was supported on an activated carbon and applied to a fixed-bed operation. A previous lab-scale study showed that CO, absorption by activated carbon impregnated with K2CO3 is not influenced by moisture in feed gases. The hydrate of K2CO1 was held in cavities of the activated carbon, and cyclic sorption/release operations were repeated according to by the following reaction: K2CO3.1.5H(2)O+CO2=2KHCO(3)+0.5H(2)O. In the present work, experiments employing a bench-scale column (54.5 mmphix800 mm) were carried out to examine performances of K2CO3-on-activated carbon. Moist 13%CO2 gas was supplied to 1.20 kg of K,CO3-on-activated carbon packed in the column to sorb CO2, followed by flushing with steam to release CO2 sorbed. The released gas was cooled through a heat-exchanger to condense the steam, giving CO2 in high purity Bench-scale behaviors of CO2 sorption/release and of column cooling were elucidated. The energy consumption for CO2 recovery was also estimated.