Coal-Direct Chemical Looping Process with In Situ Sulfur Capture for Energy Generation Using Ca-Cu Oxygen Carriers

A novel process scheme for energy production from coal with in situ sulfur capture, known as the coal-direct chemical looping process with sulfur removal (CDCL-SR), is proposed in this study. The proposed process utilizes multimetal oxide comprising the oxides of copper and calcium supported on inert SiC as the oxygen carrier to combust coal and simultaneously produce separate streams of CO2 and SO2, thus eliminating the need for downstream processing units. The computational software ASPEN Plus has been utilized to carry out detailed reactor simulations along with a thorough thermodynamic analysis of the process. The reactor modeling results indicate that the moving bed reducer can effectively convert all the carbon present in coal into CO2 while capturing sulfur in the form of calcium sulfide in the reduced oxygen carrier. The reduced oxygen carrier can in turn be oxidized using steam to produce pure SO2 stream that can be readily utilized. Process simulation results indicate that the proposed CDCL-SR process has thermal and exergy efficiencies of 86 and 51%, respectively, significantly higher than both the conventional pulverized coal Rankine cycle and Fe-based CDCL processes.