Calcium Looping for CO2 Capture at a Constant High Temperature

A calcium looping process using calcium-oxide-based sorbent for CO2 capture was demonstrated to operate at a constant high temperature in this work. First the operating temperature window of the process was determined by investigating the quasi-equilibrium and kinetics of carbonation/calcination of synthetic CaO-based sorbents. The results indicate that the process would be suitable to operate within 750-840 degrees C when the CO2 concentration is higher than 15%. Subsequently, the process was demonstrated in a lab-scale fixed-bed reactor in 20% CO2 (N-2 balance) by examining the temperature variations in the synthetic CaO-based sorbent particles. The effects of operating variables (such as operating temperature, switching time, and sample type) on the cyclic temperature variation were investigated. It was observed that the process operated in a highly stable manner over 100 cycles at 770 degrees C with the switching time of 1 min in both carbonation and calcination modes. The cost of calcium looping could be reduced significantly by operating at a constant high temperature.