Post-combustion CO₂ capture process in a circulated fluidized bed reactor using 200 kg potassium-based sorbent: The optimization of regeneration condition

The Potassium-based dry sorbent CO₂ capture process can selectively capture CO₂ from flue gas without toxicity. In this study, the optimization of regeneration condition was investigated to pursue economical CO₂ capture process in a circulated fluidized bed reactor as most energy for CO₂ capture is consumed in the sorbent regeneration. One important part for CO₂ capture process is to produce highly concentrated CO₂ during the sorbent regeneration in the conditions of CO₂ rich with a presence of H₂O, which thermodynamically reduces the sorbent regeneration efficiency at low temperature. This could be overcome by increasing the regeneration temperature although the sorbent regeneration energy increases. The dry sorbent performance in the carbonator was evaluated by changing the temperature, CO₂ and H₂O concentration in the regenerator, which showed about 88% CO₂ removal efficiency and 5.6 wt% dynamic sorption capacity. The dry sorbent was sampled at each operating condition to confirm the dry sorbent performance, evaluated over CO₂ concentration. The optimal regeneration condition was obtained by considering CO₂ removal efficiency, dynamic sorption capacity and regeneration energy. Finally, the optimal regenerator temperature was determined to be approximately 468 K where the CO₂ capture process in the circulated fluidized bed reactor showed 95% for CO₂ purity.