| Oxygen nozzle is an indispensable device for converter steelmaking.Its performance directly affects the main economic indicators such as steel production,quality,variety,raw material consumption and cost.The criteria for the evaluation of lance nozzles are primarily the oxygen jet characteristics of the smelting process.During the oxygen top-blown converter steelmaking process,oxygen passes through the lance nozzle to form an oxygen jet that impinges on the surface of the bath and penetrates into the bath for mechanical agitation.If the mechanical agitation is strong and uniform,the chemical reaction during the smelting process is smooth and fast.Therefore,it is important to study the oxygen nozzle shooting behavior and the interaction with the molten pool,and to understand the working principle of the oxygen top blowing converter and to guide the actual smelting of the oxygen top blowing converter.In view of this,this paper takes a steel 260 t converter 5-hole nozzle as a prototype,and further improves the characteristics of the nozzle in the process of converter smelting.Firstly,the traditional equal-flow equal-angle six-hole nozzle and new variable flow are redesigned.Variable angle six-hole oxygen nozzle.Secondly,a three-dimensional CFD model of the converter's compressible oxygen jet was established.The jet characteristics and coalescence behavior of the traditional equal-flow equal-angle oxygen lance and the new variable-flow variable angle nozzle were studied,and the impact area with the molten pool was compared.Then,a 1:7hydraulic model of the top-blown steelmaking converter was established.The shape of the impact pit under different operating parameters and the stirring capacity in the molten pool were investigated,which provided a verification basis for numerical simulation.Finally,a two-dimensional gas-liquid two-phase flow model was established to study the interaction between the jet and the molten pool under high temperature conditions.The gas-liquid interface behavior of the jet impinging molten pool was explored,the mechanism of droplet splattering was revealed,and the flow state of molten steel in the molten pool was analyzed.The results show that the multiple jets are ejected from the nozzle or along the axis of the orifice.However,due to the turbulent entrainment,a pressure difference is generated between the side of the nozzle and the opposite side of the nozzle,resulting in the center of the jet deviating from the axis of the orifice,and the center of the jet is close to the center of the nozzle.Produce a coalescence behavior.The two sets of nozzles of the new six-hole oxygen nozzle are staggered due to different flow and inclination angles.Before the unfusion,the angle of the oscillating angle of thevariable angle nozzle is large,and the distribution range of the jet is large.When the stream is fused,the size of the nozzle is changed.The hole is step-by-step fusion.As the fusion distance of the stream increases,the flow gathers slowly,which causes the distance of the stream to shift the center line of the nozzle to increase,so that the impact area of the molten pool increases.Under the same nozzle position,the dead zone of the new six-hole oxygen lance is smaller than the traditional six-hole lance,and the velocity distribution in the weld pool is more uniform,and the mixing effect of the molten pool is better.At the same flow rate,compared with the conventional nozzle,the mixing time of the new nozzle is shortened by 10 s on average at different gun heights. |
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