Flow sheet model evaluation of nuclear hydrogen steelmaking processes with VHTR-IS (very high temperature reactor and iodine-sulfur process)

Nuclear hydrogen steelmaking (NHS) and nuclear hydrogen partial reduction steelmaking (NHPRS) systems were proposed using very high temperature reactor, and thermochemical hydrogen production iodine-sulfur process. Heat input and CO2 emissions of these systems were analyzed by heat and mass balance calculation. Total net heat input to the NHS system was 28.4 GJ/t-high quality steel (HQS), including material production, material transportation, and power generation. This value was much larger than that of a blast furnace steelmaking (BFS) system of 17.6 GJ/t-HQS. Reduction of hydrogen consumption in the shaft furnace and electricity consumption in the electric arc furnace were desired for lowering the heat input. Total net heat input of a NHPRS system was 31.9 GJ/t-HQS. Optimization of operation parameters such as the reduction ratio of partial reduced ore (PRO) and ratio of the PRO input to the blast furnace is desired to decrease the heat input. CO2 emissions of the NHS system and the NHPRS system were 9% and 50% of that from the BFS system. Substitution of coal by hydrogen and reduction of transportation weight contributed to the reduction. Steelmaking cost was also evaluated. When steelmaking scale of each system was unified to one million t-HQS/y, NHS was economically competitive to BFS and Midrex steelmaking. And NHS was advantageous at higher cost of resources. (author)