CO2 Removal in Packed-Bed Columns and Hollow-Fiber Membrane Reactors. Investigation of Reactor Performance

The CO 2 absorption performance of hollow-fiber membranes and conventional packed-bed column reactors under similar operating conditions was evaluated. Two-scale, nonisothermal, steady-state models were used to simulate the reactors behavior. The membrane reactor model accounts for CO 2 diffusion in gas-filled membrane pores, CO 2 and amine diffusion accompanied by chemical reaction in liquid-filled membrane pores, and CO 2 and amine diffusion accompanied by chemical reaction in the liquid film zone surrounding the inside membrane wall. The packed-bed column reactor model interconnects a two-fluid 2D hydrodynamic platform with 2D mass and energy transport equations in the gas and liquid phases and nonlinear differential equations governing diffusion and reaction in the liquid film. In the absence of membrane wetting, the hollow-fiber membrane reactor outperforms the packed-bed column reactor with similar volume and specific surface area. This is not the case under membrane wetting conditions, when at low specific surface areas the packed-bed column reactor can outperform the membrane reactor. However, as the hollow-fiber membrane reactors can be stacked with very high specific surface areas in the same reactor volume, the performance of this type of reactor remains better even under partial wetted membrane conditions.