Oxygen blast furnace (OBF) has two well-recognized shortcomings, i.e., thermal shortage in the upper BF and overheating in the lower BF. Reducing gas injection is an effective method to overcome them. Based on an industrial 380 m³ OBF, the effect of hearth gas injection, and the effect of hearth and shaft co-injection on the global performance indicators and in-furnace states are numerically investigated over a wide range of blast oxygen contents. This is based on the recently developed 3D multi-fluid BF process model, which considers 3D layered burden structure, layered cohesive zone (CZ), deadman profile prediction, trickling liquid flow, productivity prediction, and particle size degradation. Results show that, for different blast oxygen contents, by injecting reducing gas through hearth tuyeres to sustain the bosh gas volume and theoretical flame temperature, the two inherent problems of OBF can be solved simultaneously. Meanwhile, the solid fuel rate significantly reduces. On the basis of hearth gas injection, shaft gas injection can further reduce the solid fuel rate through accelerating the indirect reduction in the upper BF. Moreover, the model applicability is tested against the industrial OBF operated in Baowu, under the “Base Case” and “HyCROF” periods. Compared with the “Base Case”, the CZ location and in-furnace thermal state do not change significantly in “HyCROF”. The reason for the 30% solid fuel rate reduction lies in the sufficient physical heat and strong reducing atmosphere brought by the hearth injected reducing gas. Some guidelines for OBF design and control are proposed for general practice.

oxygen blast furnace; reducing gas injection; simulation and modeling; computational fluid dynamics