Investigation of CO2 Capture in Three-Dimensional Full-Loop Integrated Bubbling-Transport Bed Adsorber

Carbon capture using solid sorbents in fluidized bed reactors has attracted increasing attention. However, optimized design and operation require excellent control over the gas–solid contact and sorbent circulation between the adsorber and desorber reactors. In this study, the hydrodynamics and CO2 capture process using potassium-based solid sorbents in a full-loop integrated system consisting of a bubbling-transport bed adsorber and a bubbling bed desorber are investigated by using a three-dimensional two-fluid model (TFM), in which the operating parameters can be realistically adjusted. Results show that the sorbent circulation rate increases with the gas velocity in the central pipe and with the static bed height in the bubbling section of the adsorber. The pressure distribution, sorbent concentration, and distributions of the gas and solid velocities are explored, and optimized gas velocities in the bubbling section and the central pipe are recommended. The CO2 capture efficiency increases as the water vapor concentration in the inlet flue gas is increased from 8 to 18%, and the optimal water vapor concentration is identified as 14%. The results of this study are useful for the design and optimization of CO2 capture reactors with solid sorbents.