Transient-state Behaviours of Blast Furnace Ironmaking: The Role of Shaft-injected Hydrogen

Hydrogen shaft injection into blast furnaces (BFs) has a large potential to eliminate carbon dioxide emissions, yet the temporal evolution of thermal and chemical states following shaft-injected hydrogen utilisation has not been reported in the open literature. In this research, a recently developed transient-state multifluid BF model is applied to elucidate the temporal evolution of in-furnace phenomena. Besides, a domain-average method is adopted to analyse the extensive simulation data to determine the time required to attain the next steady-like state. The results show that the evolution of thermal and chemical conditions varies across different regions, with distinct characteristics near the furnace wall. The shifts in iron oxide reduction behaviour are completed within 10 to 20 h after the new operation, and the transition time points to the next steady-like states of thermal and chemical conditions are different. As the hydrogen flow rate increases, the average transition time decreases. However, 2 to 4 days are required for the studied BF to reach a new steady-like state in the considered scenarios. The model offers a cost-effective approach to investigating the transient smelting characteristics of an ironmaking BF with hydrogen injection.