Process Evaluation of Use of High Temperature Gas-cooled Reactors to an Ironmaking System Based on Active Carbon Recycling Energy System

摘要

Reducing coking coal consumption and CO_2 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 CO_2 electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H_2 produced by iodine-sulfur process. Both reduction of the coking coal consumption and CO_2 emissions were greater in the RWGS system than those in the SOEC system. It was the reason of the result that excess H_2 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 H_2 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 CO_2 emissions more efficiently by comparing CO_2 emissions reduction per unit heat of the HTGR.