Repetitive calcination-carbonation capability of Ca-based CO_2 absorbent

The repetitive calcination-carbonation capability of Ca-based absorbent was investigated by using a laboratory-scale vertical-tube reactor.The effect of temperatures of calcination and carbonation on the decline of absorbency was studied,and the maximal capture capability of the calcination-carbonation(CC)process and the calcination-hydration-carbonation(CHC)process was compared.The experiment on the absorbents saturated with additive was also carried out.The CO_2 capture capacity of the absorbents decreased obviously with the number of cycles,and the CO_2 capture capacity for the absorbents without any treatment declined to about 20% after 10 cycles.For example,the capture capacity declined to 20.0% from 73.4% after 10 cycles at 900℃ for calcination and 650℃ for carbonation.A mild calcination temperature and a higher carbonation temperature favored the process and the maximal capture capability could be higher.The maximal conversion ratio of absorbents for the CC process was obviously lower than that of the CHC process.The capture capacity of absorbents added with NaCl and Na_2CO_3 severely decreased,but the repetitive capability was steady.Regeneration treatment after multiple cycles could make the reactivity of absorbents reach 95% of first carbonation.