| Bottom blowing argon and electromagnetic stirring(EMGAS)are two effective stirring methods in ladle refining.On one hand,EMGAS can effectively reduce the ladle refining time,improve the steel cleanliness,reduce the energy consumption and so on.On the other hand,EMGAS can significantly improve product quality and production efficiency of steel enterprises.Based on Euler-Euler fluid model,the Maxwell equations and the Population balance equation(PBM),Three-dimensional mathematical model is developed to describe the flow field and bubble size distribution in ladle under the condition of electromagnetic stirring.Firstly,this paper gives the distribution of magnetic field generated by magnetic stirrer in ladle,and studies the effect of current magnitude,current frequency and stirring direction on the flow field and mixing time in the ladle.Then,The breakup and coalescence among the bubble is considered to investigate the flow field in the ladle.Finally,the characteristics of bubble size distribution in ladle are studied under the magnetic field.The conclusions are as follows:(1)Numerical results for the flow field when PBM is considered in the ladle agree with the experiments.(2)There are two small circulation flows in the inner flow field in the case of bottom blowing,but the EMGAS has only one single circulation flow in the ladle.(3)The speed of liquid steel near the side of the magnetic stirrer increases with the increase of the current frequency and the current.And the bigger the frequency and the current,the farther the bubble trajectory away from the center of ladle.The motion of the bubble is close to the side near the magnetic stirrer when the stirring direction is upward,and the moving trajectory of the bubble is far away from the side near the magnetic stirrer when the stirring direction is downward.The greater the frequency and the current,the shorter the mixing time in the ladle.(4)The bubble is large near gas-liquid region center,and the bubble is small near the boundary of gas-liquid region.From the center of the gas-liquid two-phase region to the gas-liquid boundary,the bubble diameter is gradually reduced.The bubble diameter increases with the increase of ladle height,and the growth rate of the bubble diameter is the fastest at the entrance,and increases slowly with the increase of the ladle height.(5)Without electromagnetic stirring,the bubble size distribution in ladle is centralsymmetry.With the electromagnetic stirring,large bubbles tend to accumulate near the side of ladle center,most of small bubbles tend to accumulate near the side of ladle wall.The range of the bubble diameter distribution under the upward stirring and the downward stirring is opposite.(6)The greater the frequency and the current,the greater the bubble diameter in the ladle,and the direction of electromagnetic stirring has no significant effect on the maximum bubble diameter. |
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