Jet Characteristics of a High-Mach-Number Oxygen-Lance Nozzle Under High Oxygen Pressure

In response to some problems that occurred when a steel mill in China transitioned to automatic steelmaking, a high-Mach-number oxygen lance was designed and forged. The designed oxygen pressure was 1.01 MPa; at this high oxygen pressure, the Mach number of the nozzle outlet could reach 2.15. A three-dimensional two-phase flow model was established by numerical simulation, and the jet characteristics of the high-Mach-number oxygen-lance nozzle at different oxygen-supply pressures and the impact of the jet on the melting pool were analyzed and studied. The jet was found to be most stable in the oxygen-supply-pressure range 0.9 to 1.01 MPa. Considering the impact depth, impact area, velocity distribution in the molten pool, and mixing time, a combined top- and bottom-blowing process could optimize the mixing effect of the nozzle on the molten pool. Application of the nozzle in industrial practice greatly improved the stability, quality, and efficiency of smelting and lengthened the life of the oxygen-lance nozzle by 100 furnaces.