| During the iron and steel production process,ladle tapping process is an indispensable part of steelmaking process.At present,the sliding nozzle system is widely used in ladle tapping,and the upper nozzle is filled with stuffing sand to block the molten steel.The use of stuffing sand can pollute the molten steel and result in the automatic casting rate of ladle less than 100%,which influence steel cleanliness and production rhythm.An Electromagnetic Induction Controlled Automated Steel Teeming technology(EICAST)uses Fe-C alloy particles that the composition is same or similar with the molten steel to replace the stuffing sand.The induction coil in the nozzle brick which installed in the bottom of the ladle is used to melt the Fe-C alloy blocking layer,the automatic casting can be realized and the problem caused by the stuffing sand can be completely solved.However,due to the influence of high temperature steel heat conduction,the maximum temperature of the coil after heat insulation treatment can still beyond 600℃ which is close to its softening temperature before electrified heating.In addition,the induction coil will generate heat in the process of electrified heating and the coil temperature will further increase,which seriously hinder the further development and practical application of the EICAST technology.Therefore,this paper used the method of combining numerical simulation with experiment,The cooling effect of different cooling methods on the induction coil in different stages was analyzed.First of all,the cooling effect of gas cooling on the induction coil was analyzed from three aspects:gas flow direction,gas initial temperature and gas flow within 2 min before electrified heating and molten steel refining 180 min.Secondly,the induction coil was cooled by air mist two-phase cooling method within 2 min before electrified heating.The cooling effect of initial temperature of liquid drop,water flow rate and gas flow rate on the induction coil was analyzed.Finally,the cooling effect of the induction coil was analyzed by the combination of gas cooling in refining process and gas mist two-phase cooling before electrified heating.The main conclusions of this paper are as follows:(1)Reducing the initial temperature of the gas has little effect on the cooling effect of the induction coil within 2 min before the electric heating.During molten steel refining 180 min,for every 40℃ decrease in the initial temperature of the gas,the temperature of coil bottom position decrease about 15℃,the temperature of other points in coil is reduced about 35℃when the gas flow rate is 100 L/min.(2)The cooling effect of the induction coil can be improved by increasing the gas flow rate in the refining process.When the gas get into the pipe for cooling from the upper high temperature,the coil temperature can be decreased lower than 220℃ when the gas flow rate is 150 L/min,and increasing the gas flow rate has no effect on the cooling effect of the induction coil.(3)The induction coil can be cooled by air mist cooling within 2min before heating.With the increase of the water flow rate,the cooling effect of air mist mixture is enhanced for the induction coil,and with the increase of the gas flow rate,the cooling effect of the air mist mixture is weakened for the induction coil.When the gas flow rate is 50 L/min and the water flow rate is 15 L/h,the coil temperature is closed to 350℃.(4)On the basis of the induction coil is cooled by gas whose is 150 L/min from the top part of the coil in the refining process,the induction coil is cooled by the air mist mixture which the gas flow rate is 50 L/min and the water flow rate is 15 L/h from the bottom part of the coil before the electric heating,the coil temperature is reduced to the range of 100～165℃,which can solve the problems of high temperature and large temperature gradient from the top to the bottom when the coil is energized. |
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