Characterization of Supersonic Gas-solid Blowing Jets from a Cluster Oxygen Lance at Different Powder Flow Rates and Ambient Temperatures

In the steelmaking process, lime is usually fed into the bath as a lump through the charging holes at the top of the furnace, the slag-making material floats on the slag surface, and the melting speed is slow, resulting in deep dephosphorization of molten steel is difficult. In order to improve the kinetic conditions of the molten pool and increase the velocity of the powder impacting the molten pool, this paper designs a cluster-type oxygen lance containing supersonic gas-solid blowing, which effectively solves the above problems. The jet law of supersonic gas-solid blowing oxygen gun is investigated by numerical simulation with the following results: i) Supersonic gas-solid injection reduces the peak velocity of the gas-phase jet but effectively mitigates the decay of the gas-phase velocity and extends the jet length; ii) The low-temperature gas in the center of the jet acquires energy from the high-temperature environment generated by the external ring-seam gas through convection, and thus expands sufficiently to provide sufficient energy for particle acceleration; iii) When the powder particles are larger than 0.3 kg/s, the gas-solid jet will flow at subsonic speed, greatly reducing the ability to accelerate particles, the design of supersonic gas-solid spray gun need to consider the appropriate powder-gas ratio. These findings will provide a certain research basis for supersonic lime powder delivery in the steelmaking process, which is of significance for efficient dephosphorization smelting with less slag in electric arc furnaces.