| The single snorkel RH is a new type of vacuum refining device,which has the advantages of high refining efficiency,simple structure and low production cost,and is suitable for the vacuum refining of small and medium size ladle.Increasing the circulating flow rate of the single snorkel RH refining device,increasing its mass transfer speed and mass transfer uniformity,is of great significance to improving the efficiency of vacuum refining.In this paper,the 65 t single snorkel RH model is used to reveal the law of molten steel flow in the single snorkel RH vacuum refining device under different process parameters through numerical simulation,which provides theoretical support for the optimization design and actual production of the single snorkel RH vacuum refining device.The simulation results show that,regardless of single nozzle or multi-nozzle,the circular flow of molten steel increases with the increase of the blowing rate in the range of 300～1100 NL/min.Under the same blowing volume,the arc-shaped three-nozzle RH circular flow is the largest,and the single nozzle RH circular flow is the smallest.With the increase of the number of nozzles,the cross-sectional area of the single snorkel RH upward stream increases,driving more molten steel to flow,the speed of the upward stream gradually decreases,and the downward stream speed of the molten steel gradually increases.The submerged depth has a certain influence on the circular flow of RH molten steel.The circular flow of molten steel is the largest when the submerged depth is 500 mm.Under the same blowing volume,comparing single nozzle,double nozzle,straight three nozzles and arc-shaped three nozzles,the average speed of a single nozzle on the steel surface in the vacuum chamber is the largest,which is beneficial to increase the mass transfer rate;when the blowing volume is greater than 300 NL/min.The value of a single nozzle is the largest,which is conducive to uniform mass transfer on the molten steel surface.Under the same blowing volume,the steel liquid level in the double nozzle of RH vacuum chamber is the largest,which is beneficial to the decarburization reaction in the vacuum chamber.When the distance between the two nozzles is within the range of 0.1～0.5 m,the circular flow rate of molten steel increases with the increase of the distance.When the distance is greater than 0.5 m,the circular flow rate decreases rapidly.When the distance between the two nozzles is 0.5 m,Circular flow rate and better flow field can be obtained.Both straight and arc arrangement of three nozzles can get better up stream and down stream,but the circular flow of arc distribution is larger than that of straight distributionComparing the single snorkel RH with the traditional RH,the rising stream velocity of the single snorkel RH is relatively uniform,while the traditional RH rising pipe has a higher velocity at the pipe wall,and the central part has a small flow velocity,which severely scours the inner wall of the rising pipe.Under the same argon blowing flow rate(1100 NL/min),the single snorkel RH circular flow rate is about 2.25 times of the traditional RH.From the analysis of molten steel circular flow,single snorkel RH has more advantages than traditional RH.The stroke of the single-tube RH argon bubble is longer than that of the traditional RH,and the residence time in the molten steel is longer,which is conducive to the decarburization reaction.In addition,the argon gas blown in by traditional RH is mainly distributed near the pipe wall,and the erosion of the pipe wall is serious,which is not conducive to prolonging the service life of RH.The turbulent kinetic energy of the liquid surface in the single snorkel RH vacuum chamber is greater than the traditional RH.The turbulent kinetic energy of the molten steel surface is large,which is conducive to the mass transfer of molten steel.Therefore,single snorkel RH has more advantages in refining than traditional RH. |
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