Efficient CO2 capture from lime production by an indirectly heated carbonate looping process

Abstract

Lime production is associated with unavoidable process CO2 emissions that can only be avoided by CO2 capture technologies. The indirectly heated carbonate looping (IHCaL) is a promising post-combustion carbon capture technology that can be applied to lime plants with high potential for heat and mass integration. In this work, two concepts for efficiently integrating the IHCaL into lime plants are proposed and evaluated. To study and characterize these concepts, heat and mass balances were established, sensitivity analyses were performed, and key performance indicators were calculated by means of process simulations. The results show an increase of 63% in the direct fuel consumption for a highly integrated concept, but almost 30% of the entire heat input can be converted into electric power via heat recovery steam generation. Direct CO2 emissions are reduced by up to 87% when coal is used as fuel in the IHCaL process, but net negative CO2 emissions could be achieved when using biogenic fuels. Critical points for integration 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. The developed models and the obtained results will be used to further develop the integration of the IHCaL into lime plants through both experimental and numerical methods.