Numerical Simulation Of Multiphase Fluid During The Converter Steelmaking Process

The transport behavior of converter molten pool is very complex,involving many complex phenomena such as the flow,mass transfer,heat transfer,melting and chemical reaction of gas,liquid and solid between molten steel,slag and gas phase.Among them,the flow behavior of multiphase fluid is the basis of complex reaction of molten pool.Clarifying the multiphase flow behavior and its influence mechanism in the converter has important guiding significance for optimizing the converter injection process,guiding the proportion of scrap added,and improving the smelting efficiency.In this paper,a 260-ton converter in a steel plant is taken as the research object,and the multiphase flow in the converter is studied by numerical simulation.In this paper,a top-blown converter steelmaking model is established to study the change of molten steel flow rate in the molten pool under different lance positions,the change of molten steel flow rate in the molten pool under different slag parameters,and the energy transfer in the molten pool.Then,a top-bottom combined blowing model was established to explore the flow behavior of molten steel in the molten pool under different bottom blowing flow rates.Finally,the scrap model is added to the established model to investigate the influence of different proportions and different shapes of scrap on the flow of molten steel.The main conclusions are as follows:(1)The flow behavior between the supersonic oxygen jet and the interface of slag and steel is transient and random.As the lance level increases,the impact crater depth decreases and the diameter increases.The change of slag parameters has little effect on the change of molten steel velocity in the melt pool.The change in slag physical parameters produced little change in energy within the melt pool,and the change in oxygen lance had a deeper effect on the impact crater.(2)A top-bottom combined blowing model was established to analyze the flow process of molten steel in converter bath,and the flow phenomenon of bottom blowing argon floating in molten steel was described.The dead zone,low-speed zone and high-speed zone in the top-blown and top-bottom combined-blown converters are displayed by the isosurface volume wrapping method.Through quantitative comparison,it is further verified that the stirring energy in the molten pool is mainly provided by the bottom blowing.When the bottom blowing gas supply mode adopts uniform gas supply,the stirring effect of the molten pool is better when the bottom blowing flow rate is 880m~3/h.When the non-uniform gas supply mode is adopted,the flow ratio of the two groups is 1:1,which is better than other ratios.(3)Scrap has a great influence on the flow of molten steel in the molten pool.A scrap steel model with different parameters is established in the converter.The study shows that the area of molten steel velocity below 0.01 m/s in the molten pool is mainly concentrated between the bottom of the converter center and the gap of scrap steel.The existence of scrap steel hinders the floating of a part of bottom blowing argon,changes the number of vortices formed by molten steel,increases the disturbance of argon to molten steel,and is conducive to making full use of argon energy.The analysis of different proportions of cylindrical scrap in the molten pool showed that the proportion of scrap was 20%,and the stirring in the molten pool was the best.When the shape of scrap is spherical scrap,cylindrical scrap and square scrap,the wall shear force and dead zone size in the converter are different.