Effect of Operating Parameters on Carbon Dioxide Depressurized Regeneration in Circulating Fluidized Bed Downer using Computational Fluid Dynamics

Abstract

Typically, heating or high-temperature treatment has been used to regenerate solid sorbent. In this study, the depressurized regeneration using a circulating fluidized bed downer was proposed and the significance of its operating parameters was identified. Two-dimensional computational fluid dynamics were employed to systematically investigate the effects of operating parameters on carbon dioxide depressurized regeneration with potassium carbonate solid sorbent particles. The simulated model was based on a laboratory scale circulating fluidized bed downer. The chemical equilibrium model for predicting the highest outlet carbon dioxide mass fraction was then used. A central composite design was employed to identify the main, quadratic, and interaction effects of operating parameters to the regeneration process. The operating parameters consisted of the outlet system pressure, inlet gas velocity, and inlet solid circulation rate, while the response variable was the released outlet carbon dioxide mass fraction. Among the multiple operating parameters, there were two main operating parameters and their combinations, namely the inlet gas velocity, outlet system pressure, square of inlet gas velocity, and interaction between inlet gas velocity and outlet system pressure, which had great impacts on the regeneration. All the main, quadratic, and interaction effects were explained. Then, the optimal operating conditions were obtained through the response surface method.