Sensitivity analysis of CO2 capture process in cyclic fluidized-bed with regeneration of solid sorbent

Abstract

In cyclic CO2 capture processes using dry sorbents, the regeneration of sorbents is a key factor that determines the overall performance and energy efficiency. In this study, the sensitivity of capture performance and energy consumption was determined using a dynamic model for a cyclic fluidized-bed system circulating a K2CO3-based sorbent. The sensitivity study focused on the sorbent properties, operating conditions, and regenerating conditions. The performance was more sensitive to the operating conditions than the physical properties of sorbent. For the carbonator, the inlet velocity of feed gas was the most critical parameter for assessing the capture efficiency, and the CO2 content in feed gas was crucial for determining the energy efficiency. A slight increase in the regeneration temperature led to a steep increase in CO2 removal performance as well as energy consumption. To achieve CO2 removal of over 78.5%, high energy consumption in the regenerator was expected. Additionally, a high capital cost would be required to procure a large-sized regenerator or compressor. Thus, at the designing stage, the target of CO2 removal should be carefully decided for the given sorbent. By varying the sorbent properties, improved CO2 removal performance was accompanied with reduced energy consumption in the regenerator. Meanwhile, the adjustment of operating conditions led to an increase in both CO2 removal and energy consumption. Therefore, a delicate control of operating conditions was required to achieve high CO2 capture performance with reasonable energy efficiency.