2015 Volume 55 Issue 2 Pages 348-358
Reducing coking coal consumption and CO2 emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO2 electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H2 produced by iodine-sulfur process. Both reduction of the coking coal consumption and CO2 emissions were greater in the RWGS system than those in the SOEC system. It was the reason of the result that excess H2 not consumed in the RWGS reaction was used as reducing agent in the blast furnace as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H2 production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO2 emissions more efficiently by comparing CO2 emissions reduction per unit heat of the HTGR.