The Effect of Voidage on the CO2 Sorption Capacity of K-Based Sorbent in a Dual Circulating Fluidized Bed Process

The performance of the CO2 capture of a potassium-based dry sorbent was investigated in a dual circulating fluidized bed process. The dual circulating fluidized bed process consisted of a carbonation reactor and a regeneration reactor. It was operated in the continuous solid circulation mode between a fast fluidized-bed carbonator of 6 m in height and a bubbling fluidized-bed regenerator. As the solid circulation rate increased from 7 to 36 kg/m2/s, the CO2 removal of the potassium sorbent, sorbKX40, increased from 25 to 55% and the mean voidage was maintained from 0.94 to 0.99 representing the dilute phase in the fluidization regime. The continuous solid circulation behavior in a dual fluidized bed process was well expressed by a single closed loop in a pressure balance curve that indirectly explained the direction of the sorbent flow and the mean bulk densities of the gas-solid mixture. The information on hydrodynamics and sorption capacity will be used for the conceptual and scale-up design of the system.open161