CFD-DEM Modeling of CO ₂ Capture using Alkali Metal-Based Sorbents in a Bubbling Fluidized Bed

Abstract

Abstract This paper describes a CFD-DEM modeling of CO 2 capture using K 2 CO 3 solid sorbents in a bubbling fluidized bed, which takes into heat transfer, hydrodynamics, and chemical reactions. Shrinking core model is applied in reaction kinetics. Simulation and experiment results of bed pressure drop and CO 2 concentration in the reactor exit agree well. Instantaneous dynamics as well as time-averaged profiles indicate detailed characteristics of gas flow, particle motion, and chemical reaction processes. The simulation results show an obvious core-annular flow and strong back-mixing flow pattern. CO 2 concentration decreases gradually along the bed height, while regards on the lateral distribution CO 2 concentration near the wall is lower than that in the middle zone where gas passes through faster. The effect of bubbles on CO 2 reaction is two-sided: it can promote mixing which strengthens reaction, while it can be a short pass of gas which is not beneficial to reaction. The simulation is helpful for further understanding and optimal design of fluidized bed reactors of CO 2 capture.