Numerical Simulation On Inclusion Removal Behaviors During Ladle Teeming With The New Process Of Argon Blowing Around The Tapping Hole

Drain of steel from a ladle is one of the most important operations for a steel clean quality.On the one hand,for economic reasons,steel caster will always look for very small metal residuals in the ladle and too low residual steel height implies slag entrainment due to the vortex formation in the outlet nozzle.Nevertheless,such operation will increase the number of slag particles in the tundish and this will result in decreasing steel cleanliness,production and steel quality without any apparent feasible measures.On the other hand,because of the problem of field production,some steel mills can not guarantee sufficient time of argon blowing refining and standstill which results a certain amount of inclusions remained in the ladle.The new process of argon blowing around the tapping hole is a feasible solution in solving these above problem during the ladle teeming,for one thing,the technology is helpful to removing inclusions without affecting the rhythm of field production,for another thing,it can break the vortex formation and reduce the height of slag entrainment.However,the numerical simulation of inclusion removal behaviors in ladles is mostly based on the steady state.The unsteady numerical simulation of inclusion-removing behaviors in argon blowing process has not been reported.Therefore,it is necessary to carry out the numerical simulation on the new technology.The study is not only scientific significance for inclusion removal behaviors during the unsteady process,but also will it be great theoretical significant for the clean steel production and the field application of the process.In this paper,a 145 t steel ladle of a certain steel plant is used as a prototype.The fluid mechanics software FLUENT is used to simulate gas-liquid-slag by VOF model and argon-inclusion by DPM model.For the implementation of coriolis force,slag-metal interface and wall adsorption through the UDF program.The study of multiphase flow behaviors in the pouring process and also the vortex,drainage sink and slag-metal situation including slag entrainment and slag dropping in the period of draining are considered.Particularly,the effects of the slag-metal interface,the position of the tapping hole,the bottom blowing argon rate,the bottom blowing time and size of the blowing element on the inclusion removal efficiency were investigated.The main results are as follows:(1)During the teeming of new process,when the blowing rate is 0 Nl/min,the vortex formation height is 139.8 mm and the critical height of the drainage sink is 114.2 mm.When the blowing rate is 43.61 Nl/min,the critical vortex is broken,the height of the drainage sink is 101.7 mm,the simulation results agrees well with water model experiment.(2)The removal rate of inclusions totally increases with the argon-blowing time,howerever,it increases obviously before the 1000 mm height of the residual steel,after that,the removal rate of inclusions increases gradually.When the slag thickness is 120 mm under the argon-blowing condition,the critical gas rate of slag entrainment is 174.45 Nl/min.The above conclusions are verified by water model experiment.(3)There are two optimum values among the removal rates of inclusions under the given range of argon volume rate(below critical argon volume rate of slag entrainment),43.61 N1/min for small argon-blowing rate and 144.86 Nl/min for larger argon-blowing,meantime,the effect of former small argon-blowing volume rate is better.(4)Under the same experimental condition,for different eccentricities of the tapping holes,the removal effeciency of inclusions is best when the eccentricity is 2/3R.(5)Under the same experimental condition,for different argon-blowing elements,the removal rate of inclusions increases with the increase of blowing area,the removal effeciency of inclusions is best when using 3#argon-blowing element.