Preliminary design and energy analysis of a steelmaking system coupled with nuclear hydrogen based on a high-temperature gas-cooled reactor

High-temperature gas-cooled reactors (HTGRs) have promising applications in the face of current environmental and energy problems due to their inherent safety and high reactor outlet temperature. They can be used not only for power generation but also for large-scale hydrogen production. Hydrogen can be used as a direct reducing agent in steelmaking, contributing to carbon reduction in the steel industry. It is necessary to study the coupling of HTGRs and the steelmaking system.

In this study, an HTGR-based steelmaking system is proposed, which includes five submodules: reactor module, reactor intermediate loop module, hydrogen production module, power generation module, and steelmaking module; then, a multi-generation energy system was investigated. In the reactor module, two HTGRs are connected in parallel as heat source, their thermal power is 250 MW, and the reactor outlet temperature is 950 ℃. The heat from the reactor module is transferred to the hydrogen generation module and the power generation module through an intermediate heat exchanger. The hydrogen generation module uses hydrothermal decomposition based on the iodine-sulfur process to generate hydrogen. The heat required for the iodine-sulfur process is provided by helium in the intermediate heat exchanger circuit and by the extracted steam from the power generation module. The hydrogen produced by the hydrogen production module is routed to a shaft furnace (SF) as the reductant and fuel for direct reduction ironmaking, and the oxygen produced by the hydrogen production module and the electricity produced by the power generation module are routed to an electric arc furnace (EAF) for steelmaking. The iodine-sulfur process efficiency, the power ratio of the power generation module to the reactor, the percentage of direct reduction iron in raw materials on the EAF system capacity, and the carbon emissions of the system are analyzed.

In a steelmaking system with heat supplied by two 250 MW HTGRs, 1.35 t of iron ore is required to produce 1 t of steel when the power ratio of the power generation module and the hydrogen generation module is 1∶1, the proportion of direct reduction iron in the raw material is 90%, and the iodine-sulfur process efficiency is 37.8%. Simultaneously, the system can deliver 63.0 MW (4.97 GJ for 1 t of steel) of electric energy to the power grid, and the steel production rate is 45.6 t/h. The parameter analysis shows that increasing the hydrogen production efficiency of the iodine-sulfur process can significantly increase the steel yield; however, the power consumption of the iodine-sulfur process module increases simultaneously, which reduces the output to the power grid. The steelmaking system proposed in this paper has very low CO₂ emissions. When the proportion of directly reduced iron in the EAF is 90%, only 17.2 Nm³ (33.8 kg) of CO₂ is emitted in producing 1 t of steel.

Therefore, coupling the HTGR hydrogen production with the steelmaking system has great application potential for significantly reducing the CO₂ emissions of the steelmaking industry and eliminating the dependence on coke.