Predictcion of Next-Generation Ironmaking Process Based on Oxygen Blast Furnace Suitable for CO2 Mitigation and Energy Flexibility

In the integrated steel works, huge quantities of coal and other fossil materials are consumed as reducing agents and energy resources. The steel industry must now deeply reexamine its utilization of carbon and energy from the viewpoints of global warming and energy security. Against this background, this paper focuses on the progressive design of an ambitious blast furnace for the future. Several blast furnace processes including the current blast furnace and the oxygen blast furnace were examined by using a material and energy balance model of the integrated steel works. First, the current blast furnace was evaluated considering expanded use of hydrogen-rich injectants. Next, the oxygen blast furnace with top gas recycling was examined, and the characteristics of the carbon and energy balances were clarified from the viewpoints of CO2 mitigation and the energy balance in the steel works as a whole. Although the results confirmed that CO2 emissions can be reduced by intensifying top gas recycling, the energy supply to the downstream processes became seriously insufficient. Then, the applicability of an oxygen blast furnace with a high injection rate of a hydrogen-rich gas such as natural gas instead of top gas injection was evaluated. This process, thanks to the intensified hydrogen reduction, enables the CO2 mitigation while maintaining the energy balance in the steel works. Based on the evaluation, the concept of the advanced oxygen blast furnace as a next-generation low carbon blast furnace with high energy flexibility was proposed.