| Currently,gas stirring by bottom blowing argon gas has been extensively applid in ladle furnace.However,the fluid flowing is mainly along the vertical direction so that the fluidity of fluid at the bottom edge of the ladle is poor in the ladle with bottom blowing.The highly non-uniform velocity field and a large volume of dead zone at the ladle bottom against the physicochemical processes such as alloy homogenization,inclusion removal and desulfurization reaction.In this paper,a swirl ladle refining reactor is proposed,in which the main body of liquid steel in the ladle forms transverse rotating flow and longitudinal flow by side blowing argon.Given this,the papper developed a swirling flow ladle reactor,in which the main body of liquid steel in the ladle forms transverse rotating flow and longitudinal flow by side blowing argon.The dynamic conditions of refining efficiency were improved by side blowing.A series of researches on the swirling flow ladle were carried out in this paper.A three dimentional(3D)fluid-structure coupling numerical model about the flow behavior of compressible argon gas to investigate effects of plug position,the flow rate of argon gas and the type of plug on the flow parameters(velocity,density,viscosity,etc)of argon gas at the exits of the plugs.The heat transfer between the argon gas and the plug wall in plugs has been conducted in the nodel.The slot structure,the shorter distance between plug and the liquid level,and the larger flow rate all contribute to the higher velocity of argon gas at the plug exit.When the flow rate of argon is 800 NL/min,the velocity of argon at the exit of slot plug is more than 150 m/s.When the velocity is increased to 250 m/s by increasing the argon flow rate,the velocity increases slowly.When the velocity reaches to 300 m/s,the effect of increasing the argon flow rate on the velocity is not obvious.The flow rate and the flow parameters under different conditions are fitted by mathematical formulas which are the necessary parameters for the water model experiment and numerical model of the gas-stirred ladle.The comparisons of mixing condition and inclusion removal in model ladle between bottom blowing and side blowing were investigated by physical and numerical modelling together.when the flow rate of bottom blowing is 0.18 m3/h corresponding to existing gas volume of prototype ladle,the mixing time is 118 s,and only 36.53%model inclusion has been removed with bottom blowing for 10 min.When the flow rate of four side blowing is 2.4 m3/h,the mixing time is only 27 s,and more than 90%model inclusion has been removed with side blowing for 2 min.Compared with the dual bottom blowing,the side blowing with four plugs inhenced the rotating flow,improved the average velocity of water,reduced the rate of dead zone and improved the distribution uniformity of water velocity.The four side blowing was more effective in driving the water circulation flow in each area of the water model ladle,speeding up the circulation contact between water and oil layer,thus shortening the mixing time and improving the inclusion removal rate.The industrial experiments about alloying homogenization and inclusion removal in the ladle with bottom blowing and the swirl ladle refining reactor were carried out.The operation of side blowing argon stirring in refining process is realized by the transformation and upgrading of ladle and gas supply system.Compared with single hole bottom blowing with 100 NL/min argon flow rate,the mixing time of ferromanganese alloy with 4 hole side blowing at 1600 NL/min is shortened by more than 2 times,the total oxygen content is reduced from 33 ppm to 11 ppm,and the average removal rate of large particle inclusion quantity density is increased from 0.029 cm-3·min-1 to 0.114 cm-3·min-1.A mathematical model was established to predict the mixing time and inclusion removal efficiency.The simulation results are in good agreement with the industrial test results. |
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