Numerical Simulation On Interaction Between Gas Jet And Molten Slag During Slag Bath Smelting Reduction Process

Slag bath smelting reduction ironmaking process is a cutting-edge ironmaking technology for current steel industry,which can directly uses non-coke coal powder and fine iron ore powder to produce hot metal.The process has the advantages of concise flow,lower production investment,lower energy consumption and less environmental pollution.Gas jet behavior and its interaction with molten slag are the roots of the transport phenomena such as slag bath flow and mixing,cavity pattern,slag-gas interface pattern and slag splashing during the whole reduction process.It is also closely related to the momentum,heat and mass transfer of the entire smelting process.Therefore,studying the gas jet behavior and its interaction with molten slag during the slag bath smelting reduction process has important theoretical significance and practical application value for the design of smelting reduction reactor and optimization of operating parameters.In this paper,a HIsmelt smelting reduction furnace with an annual output of 800,000 tons was chose as the research object.A three-dimensional multi-phase VOF model for the interaction between gas jet and molten slag during the slag bath smelting reduction process was established.The effects of top-blown gas flow rate,top-blown gun position,slag viscosity and slag surface tension on the cavity size,flow characteristics of the slag bath and slag splashing were investigated,respectively.Meanwhile,the effects of side-blown gas flow rate,side-blown angle and side-gun immersion depth on the transient characteristics of the slag bath flow,the mixing characteristics of the slag bath and the macro-parameter distribution characteristics of slag splashing were also studied.Furthermore,based on the numerical simulation results,the equation of the axis trajectory of the side-blown jet was modified and the mathematical expressions of the key control parameters were obtained.The following conclusions can be drawn:(1)Under the action of the top-blown gas jet,the depth and diameter of the cavity show oscillating and periodic characteristics.With the increase of the top-blown gas flow rate,the diameter and depth of the cavity increase.With the position of the top-blowing gun increases and the slag viscosity increases,the depth and diameter of the cavity gradually decrease.While,the influence of slag surface tension on the cavity size is not obvious.(2)Under the action of the top-blown gas jet,the slag splashing has transient characteristics.Increase the top-blown gas flow rate and lower the top-blown gun position,strengthen the fluctuation range of the slag-air interface,and make the slag droplets spray violent.However,compared with the operating parameters of the smelting reduction process,the change in the physical properties of the molten slag has a relatively weak effect on the slag splashing.(3)Under the action of side blowing gas jet,increasing the side blowing gas flow rate,side gun angle,and side gun immersion depth are all conducive to increasing the internal circulation area of the slag bath,improving the fluidity of the slag bath,and reducing the mixing time of the slag bath at the same time.The influence of the side blowing gas flow rate and the side blowing angle on the slag droplet trajectory are significant.As the side blowing flow increases,the horizontal spray distance and vertical spray height of slag droplet increase.The smaller the side blowing angle,the longer the horizontal spray distance of the slag droplet and the lower the vertical spray height.However,the effect of the immersion depth of the side gun on slag splashing is not significant.(4)The axial trajectory of the gas jet under different side blowing conditions extracted by numerical simulation method is consistent with the trend of theoretically derived axial trajectory of the gas jet.Based on the numerical simulation results,the dimensionless trajectory equation of the side-blown gas jet is modified as:#12 The mathematical function expressions of the key parameters K1 and K2 in the equation are fitted as:(?)...