CO2 capture efficiency and energy requirement analysis of power plant using modified calcium-based sorbent looping cycle

Abstract

This paper examines the average carbonation conversion, CO 2 capture efficiency and energy requirement for post-combustion CO 2 capture system during the modified calcium-based sorbent looping cycle. The limestone modified with acetic acid solution, i.e. calcium acetate is taken as an example of the modified calcium-based sorbents. The modified limestone exhibits much higher average carbonation conversion than the natural sorbent under the same condition. The CO 2 capture efficiency increases with the sorbent flow ratios. Compared with the natural limestone, much less makeup mass flow of the recycled and the fresh sorbent is needed for the system when using the modified limestone at the same CO 2 capture efficiency. Achieving 0.95 of CO 2 capture efficiency without sulfation, 272 kJ/mol CO 2 is required in the calciner for the natural limestone, whereas only 223 kJ/mol CO 2 for the modified sorbent. The modified limestone possesses greater advantages in CO 2 capture efficiency and energy consumption than the natural sorbent. When the sulfation and carbonation of the sorbents take place simultaneously, more energy is required. It is significantly necessary to remove SO 2 from the flue gas before it enters the carbonator in order to reduce energy consumption in the calciner. ► Compared with limestone, much less makeup of the limestone modified with acetic acid is needed. ► Achieving 0.95 of CO 2 capture without sulfation, 49 kJ/mol CO 2 is saved for modified sorbent. ► Modified limestone has greater advantages in CO 2 capture efficiency and energy consumption. ► It is highly necessary to remove SO 2 from the flue gas before carbonation for energy saving.