Process Integration of Indirectly Heated Carbonate Looping in Lime Plant for Enhanced CO2 Capture

Abstract

Lime (CaO) production emits significant amounts of CO2 through both the calcination reactions and the fuel combustion process. In order for the lime industries to reduce their mainly non-avoidable CO2 emissions, the deployment of carbon capture and storage (CCS) technologies appears as a necessity. One very promising carbon capture method is the indirectly heated carbonate looping (IHCaL). This paper aims to investigate two novel IHCaL concepts, the tail-end and the fully integrated process in order to provide a better understanding of their integration in the lime sector. The concepts are developed and simulated in Aspen PlusTM, heat and mass balance equations are established and a detailed sensitivity analysis is performed. The tail-end process is ideal for retrofitting of existing lime plant, whereas a newly-build lime plant could use the fully integrated IHCaL concept in order to achieve higher CO2-capture and lower energy consumption. The numerical results for the aforementioned scenarios, revealed that high carbon capture efficiency, 92% and 94% respectively, can be achieved at both concepts. Moreover, the power generation from the heat recovery steam cycle is calculated. Key parameters for effective integration of the concepts are the preheating of the combustion air, the efficiency of the sorbent solid-solid heat exchanger and the utilization of the sorbent purge as lime product.