Numerical analysis of CO2 capture process with potassium-based sorbent in a three-dimensional fluidized bed

Abstract

CO2 capture process with potassium-based sorbents in fluidized beds is an emerging technology in industries, yet the in-furnace solid transportation and thermal characteristics are still lacking. In this work, the CO2 process capture with K2CO3 adsorbents in a three-dimensional fluidized bed is numerically explored using a recently developed reactive multiphase particle-in-cell model under the Eulerian-Lagrangian framework. After model validation, the spatial distribution of K2CO3 particles and the effect of key operating parameters on the flow and thermal behaviours in the fluidized bed are investigated. The results indicate that elevating the particle size distribution enhances CO2 capture and increases the absorbent temperature due to the extended residence time of K2CO3 particles and the resulting enhanced exothermic carbonation reactions. Enlarging the inlet gas velocity increases the gas concentration in the reactor outlet because a part of CO2 without enough time to react with K2CO3 particles is entrained out of the reactor by bubbles with the increase of gas velocity, indicating the optimal inlet gas velocity (0.71 m/s) for CO2 capture using K2CO3 adsorbents in this fluidized bed. The particle temperature rises with enlarging inlet gas velocity due to enhanced exothermic carbonation reactions. The results obtained can help to understand the regularity of CO2 capture process based on K2CO3 absorbents in fluidized beds.