Reactor design and process optimization in chemical looping combustion: Insights into fuel types, oxygen carriers, and process design

Chemical looping combustion (CLC) is a novel technique developed for inherent carbon capture and storage (CCS). CLC utilizes an oxygen carrier (OC) to transport oxygen to the fuel for combustion, hence making the process oxy-fuel combustion. This article aims to review the process of CLC in terms of improving carbon capture efficiency and fuel conversion by studying the reaction mechanism, effect of temperature and pressure, and the effect of reactivity of OC towards fuel. The applications of several reactors, including fluidized bed reactor, have been discussed with reference to the operating conditions employed. The quantitative findings reported in various studies proved the efficient performance of copper based carriers achieving efficiency as high as 93 % when the gasification temperature was 930°C. Fuel conversion efficiencies reach 89–93.5 % for solid fuels like pine sawdust with Cu-based carriers, and up to 100 % for liquid fuels like glycerin and propane using metallic and nickel-based oxygen carriers, respectively. Carbon capture efficiencies vary, with pet coke achieving 97 % using ilmenite and Mn-based carriers.The energy duty for CLC is estimated at 0.3 GJ/tCO₂, with studies showing a 6 % reduction in CAPEX and a 14 % drop in OPEX compared to amine-based absorption. Future scope and challenges to be addressed in the chemical looping studies are identified.