A Numerical Study of the Thermochemical and Aerodynamic States of H₂-intensive Direct Reduction Shaft Furnace

In the urgent pursuit of deep decarbonization, the steel industry has paid significant attention to the hydrogen-intensive direct reduction process, where the H₂-to-CO (volume) ratio of feed gas for the shaft furnace (SF) is increased compared to the current level. In this work, the reduction process of iron oxide pellets in the SF is investigated numerically to clarify how the in-furnace thermochemical and aerodynamic states are affected by increasing hydrogen content, with the goal to provide guidelines for more efficient operations of the unit. Multiscale modeling is conducted to investigate the complicated gas–solid countercurrent reactive flows in the SF where the reduction behavior of an individual iron oxide pellet is described using a three-interface unreacted shrinking core model. The results show that an increase in the hydrogen content leads to a lower temperature level and hence a deteriorated thermochemical state. It also induces a lower gas pressure drop over the in-furnace packed bed.