Experimental Results of Post-combustion CO₂ capture in a CFB-type Reaction System Using 85 kg PEI-based Dry Sorbents

In this study, the high-concentrated CO2 has been recovered in the CFB-type dry sorbent CO2 capture process using 85 kg PEI-based sorbents, which were developed by KAIST. The CO2 uptake was measured by TGA was 0.067 kgCO2/kg-solid. The process consists of a fast fluidized bed type sorption reactor, a bubbling fluidized bed type regenerator and sorbent cooler. The 85 kg of sorbent was charged to the process and the solid circulation rate, which was quantitatively controlled by manipulating the rpm of the rotary valve, was 145 kg/h so that it took about 35 minutes for the sorbents to cycle through the process. The CO2 removal efficiency at absorber and CO2 purity at regenerator were measured or calculated with an on-line IR gas analyser. The dynamic sorption capacity was calculated using the amount of CO2 absorbed in the absorber and the solid circulation rate. The performances were as follows: about 60% of the CO2 removal efficiency, 100 kg/day of the CO2 removal rate, 91% of the CO2 purity, and 2.9 wt.% of the dynamic sorption capacity. As a result, the dynamic sorption capacity was rather low, about 43% of the sorbent performance measured by TGA, because the solid residence time in the sorption reactor was insufficient. If the height of the sorption reactor would be increased to ensure the solid residence time enough to increase the dynamic sorption capacity to 0.04 kg-CO2/kg-solid, then 85% CO2 removal efficiency and 138 kg/day CO2 removal rate would be possible.