| In metallurgical production,the molten steel temperature will directly affect the smooth operation of continuous casting and other processes.Therefore,it is significant to study the law of temperature drop of liquid steel in the ladle during transportation and pouring,to realize the accurate prediction of the temperature of tapping,and to maintain the stable temperature of molten steel,which is of great significance to improve the quality of steel products and has obvious economic benefits.A three-dimensional model for ladle thermal cycling process was established,and the finite element commercial software FLUENT is used to simulate the thermal properties of ladle and molten steel during the ladle baking,standing,pouring and empty process on the basis of experimental data verification.The temperature of ladle lining changed with time in different process,the heat loss of wall and the temperature drop of molten steel were obtained.During the thermal cycling,the effects of different refractory materials on the heat loss of ladle lining,the temperature drop of molten steel and the tapping temperature were studied.Each refractory material layer is in the state of heat storage and the working layer gets stable first in ladle baking process.During the standing process of the molten steel,the ladle refractory material is still in the state of heat storage state,the working layer temperature rises quickly and the heat storage loss of working layer is bigger.The total heat loss of molten steel during casting is mainly due to the heat loss in ladle wall and surface heat transfer from covering slag surface.The outer wall surface temperature of the conventional ladle was 209?at the end of baking;during the standing process,the temperature drop of molten steel is 145?;the temperature drop of molten steel during casting is 25?,the average cooling rate of molten steel is 0.5?/min.The heat loss of ladle wall is about 50%,and the heat loss from covering flux is about 26%.The outer wall temperature of the improved ladle was 175? at the end of baking.After the standing process,the temperature drop of molten steel is 144?;the temperature drop of molten steel during casting is 24?,the average cooling rate of molten steel is 0.48?/min,the wall heat loss accounted for 52%,heat loss from covering flux surface accounted for 27%.The temperature of the molten steel at the end of the pouring of the improved ladle was 1542?,which was 3? higher than that at the end of the conventional ladle.The results indicate that it is not very accurate to evaluate the insulation effect of ladle with ladle shell temperature.Though WDS insulation layer can reduce the temperature of ladle surface,as a result to reduce the heat loss transported from the ladle wall,it is not obvious to reduce the total loss of molten steel.The heat loss of ladle lining material is the main heat loss.Taking measures to reduce the specific heat capacity of the working layer can significantly improve the thermal insulation performance of the ladle.With the reduction of the specific heat capacity of the wall working layer,the temperature drop of ladle in the process of standing and pouring has obvious difference.When the specific heat capacities of the working layers were 1050J/kg·K,525J/kg·K,210J/kg·K,the temperature drop of molten steel during the standing of molten steel is 144?,118? and 97? respectively,and the temperature drop during casting was 24? 18? and 15? respectively.Reduction of the specific heat capacity of the wall working layer can reduce the tapping temperature above 20-30?.The effect of reducing the specific heat capacity of the permanent layer on the insulation performance of the ladle is not obvious on the basis of the existing permanent layer material.When the thickness of the covering flux is about 40-50mm,the temperature drop per minute of molten steel tends to be gentle.It is recommended that the thickness of the covering flux is 40mm. |
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