Study On Transmission Behavior In Channel Induction Heating Tundish

Channel induction heating is one of the effective methods to achieve low superheat pouring of the tundish,which can effectively compensate the heat loss of the molten steel in the tundish and improve the quality of the cast slab.However,there is still a lack of systematic research on the heating power factor in the channel induction heating tundish at home and abroad.Due to the limitation of the length of the linear channel,there is a problem of low heating efficiency in actual production at the same time.On the basis of an one-strand channel-type induction heating tundish used in a steel mill,a three-dimensional unsteady-state mathematical model of is built to study the influence of channel heating power on the flow field,temperature field,turbulence intensity and inclusion removal in the tundish.At the same time,based on the arc-shaped channel,a slanted channel-type induction heating tundish is proposed.According to the channel inclination,channel spacing,channel diameter and channel tilt angle,the method of numerical simulation is used to study the flow,heat transfer and inclusion transmission behavior in the tundish.(1)In the linear channel induction heating tundish,when there is no induction heating,the average temperature in the pouring zone is lower,and the impact of molten steel on the front wall of the pouring zone is stronger.When the heating power is 300～500 kW,the buoyancy of the molten steel increases,which suppresses the downward trend of the stream.The average temperature in the pouring zone increases,but there is a phenomenon of low-temperature stratification.When the heating power is 600～700 kW,the flow characteristics of molten steel are good.The temperature stratification is basically eliminated,and the removal rate of inclusions is gradually increased.When the heating power is 800～900 kW,there will be a return flow returning from the front wall of the pouring zone and flowing along the bottom of the ladle.The uniformity of the temperature field and the removal rate of inclusions also begin to decrease.When the heating power is 1000～1100 kW,the buoyancy of the molten steel is strong and the vortex core is close to the liquid surface.The surface of the molten steel fluctuates greatly,which is not conducive to steady state pouring.In summary,the best heating power of the tundish is 700 kW.(2)On the basis of the linear channel type molten steel heating tundish,the slanted channel type tundish is formed by shortening the distance of the channel outlet.When the channel inclination is 74～77°,it will converge in the pouring area and form a good stirring effect after the molten steel flows out from the mutually inclined channels.At the same time,the growth of the channel also promotes the removal of inclusions.When the degree is 74°and 75°,there is a small circulating flow at the upper left of the pouring area,which intensifies the fluctuation of the liquid level.When the inclination of the channel rises to 80°,the impact on the liquid level increases,and a low temperature area begins to occur in the pouring area.When the channel inclination is 83～90°,the channel inclination is not enough to maintain the stirring effect in the pouring zone and the flow of molten steel gradually returns to the ordinary straight channel tundish,which decreases the removal rate of inclusions.In summary,the best channel inclination is 77°.(3)In the slanted channel type induction heating tundish,when the channel spacing(the center distance of the channel entrance)is 1.1 m,the molten steel has better flow characteristics and high inclusion removal rate.When the channel spacing is 1.2 m,the increase of the channel outlet distance weakens the stirring effect of the molten steel.A small circulating flow is generated at the upper left of the casting area,and the low temperature area also begins to appear.When the channel spacing is 1.3 m,there is a strong circulating flow at the bottom and top of the pouring zone,which has a strong impact on the bottom and liquid level of the ladle,and the temperature stratification is further increased.When the channel spacing is 1.4 m,the turbulence intensity at the channel exit is strong,and the molten steel has an obvious upward trend,which reduces the stability of the liquid level.In summary,the best channel spacing is 1.1 m.(4)For the slanted channel induction heating tundish,when the diameter of the channel is 100～120 mm,the flow rate of the molten steel in the channel and the channel exit area increases significantly,causing a strong impact on the inner wall of the channel,the front wall of the pouring area and the liquid level.The average temperature of molten steel is higher but the uniformity of the temperature field is poor.When the channel diameter is 140 mm,the molten steel in the pouring zone is well stirred.The temperature field and turbulence intensity distribution are more uniform,and the removal rate of inclusions is aiso higher.When the channel diameter is 160～180 mm,there is a small circulating flow at the upper left and bottom of the pouring zone.the stability of the liquid level is reduced,and the molten steel is easy to flow directly from the nozzle,which reduces the average residence time of the molten steel in the ladle.The average temperature of the pouring zone drops significantly,which shows the poor heating effect.In summary,the best channel diameter is 140 mm.(5)For the slanted channel induction heating tundish,when the channel tilt angle is-2°(upward),the upward trend of molten steel is obvious affected by the upward trend of the channel,which has a strong impact on the liquid level.And there is an obvious low temperature zone in the upper right,which shows the poor heating effect of molten steel.When the channel tilt angle is 0～2°,the flow mode of molten steel is more complicated,and the uniformity of the flow field distribution is poor.When the channel tilt angle is 4°,the physical fields in the pouring area are evenly distributed,and the removal rate of inclusions is increased.When the channel tilt angle is 6°,due to the excessive downward tilt,the molten steel directly impacts the bottom and front wall of the pouring zone.The return flow generated upward after impacting the front wall aggravates the fluctuation of the liquid level,which is not conducive to steady state pouring.In summary,the best channel tilt angle is 4°.