| Realizing the constant temperature and steady pouring of the tundish plays an important role in improving the quality of the cast slab,increasing the production efficiency of continuous casting and stabilizing the continuous casting operation.However,there is a large amount of heat loss when molten steel flows in the tundish.Tundish induction heating technology has become an effective measure to compensate for this heat loss and maintain low superheat of molten steel due to its clean,safe,and precise temperature control advantages.The tundish of traditional continuous casting equipment has fixed ladle nozzle and pouring nozzle,and the distance between the two is too close to install induction heating equipment,so its structure needs to be improved.Based on the traditional tundish model,a kind of tundish induction heating butterfly valve was designed based on the induction heating device at the back of tundish and molten steel pouring.The temperature field and inclusion remo val of tundish butterfly parts were studied by using the mathematical model of magnetic/thermal/steady-state fluid coupling.The finite element model of tundish butterfly parts was established by using the finite element method based on Maxwell equation and electromagnetic constitutive equation.The electromagnetic field is solved by the combination of vector magnetic potential method and scalar potential method.The electromagnetic force and Joule heat are introduced into the momentum equation and energy equation to form the source term.Combined with RNG-k ε turbulence model,the flow field and temperature field of tundish were solved Eulerian Lagrangian method was used to study the movement law of inclusions in tundish and the removal rate of inclusions in tundish,and the tundish structure was optimized.Select the channel inclination angle as the research object,explore the flow and heat transfer behavior in the tundish at 0°,4° and 8° inclination angles,and obtain the influence of the channel inclination angle on the temperature rise in the butterfly tundish,the flow field temperature field,and the average residence time and summarize the corresponding laws.research object,explore the flow and heat transfer behavior the tracer is quickly injected at the entrance,the injection time is 1 s,and the residence time curve is obtained by detecting the concentration of the tracer at the exit(RTD)to analyze the flow in the tundish.The results show that:in the butterfly induction heating tundish,the induced current passes through the dual channels to form a closed loop,and the induced current density in the channel is much larger than other parts.Due to the skin effect and proximity effect,as well as the inlet and outlet effects,the induced current distribution in the channel is not uniform.The magnetic field in the channel is an eccentric rotating magnetic field,and the electromagnetic force is an eccentric electromagnetic force,which tightens the molten steel and causes it to produce a swirling flow.The molten steel in the channel has a greater speed than when there is no induction heating and the overall flow is more active.After entering the pouring chamber,an upward stream is generated under the action of thermal buoyancy lift,which reduces the impact on the wall refractory,helps the inclusions to float up and is adsorbed by the slag layer on the liquid surface,and at the same time,by observing the tracer distribution and induction heating The lower tracer is more evenly distributed,and the flow and heat transfer process of molten steel are improved.Under the heating power of 600,800 and 1000 kW,the maximum temperature rise in the channel is 17,28 and 36 K respectively,and the outlet temperature rise is respectively 8,18 and 27 K,which effectively solves the problem of temperature drop of molten steel during continuous casting.With 800 kW heating power,the velocity in the channel increases by about 0.4 m/s,and the tangential velocity of the channel section increases significantly,from a maximum of 0.02 m/s without induction heating to 0.13 m/s with 800 kW heating power.The movement of the inclusions in the tundish is affected by the pulsating speed and appears zigzag,and moves under the drive of the fluid.The trajectory is similar to that of the fluid.Induction heating can effectively improve the removal rate of the inclusions,especially the small-size inclusions.By observing the concentration of the tracer after a period of time,it can be obtained that the induction heating is helpful for the diffusion and uniform distribution of the tracer,and the flow field is optimized.When the inclination angle is 0° to 4°,the temperature field and flow field in the tundish are greatly affected by the inclination angle,and the influence is less when the inclination angle is between 4° and 8°.When the inclination angle is 0°,the temperature rise at the axis of the channel is 22 K,and the temperature rise at the outlet is 19 K,but the temperature rise process in the channel is complicated,the temperature distribution in the pouring chamber is uneven,and the temperature rise process at the outlet fluctuates greatly,with the maximuml8 K.The temperature distribution in the pouring chamber and the channel is relatively uniform,the heating process is relatively stable,and the overall temperature field is not different.Large;when the inclination angle is 0°,the flow in the pouring chamber is more active,the flow at the top liquid level is more turbulent,large and small vortices appear,and the flow velocity is large,up to 0.13 m/s,which is likely to cause the danger of slag entrapment.When the inclination angle is 4° and 8°,the flow of the liquid level in the pouring chamber and the top is relatively stable and uniform.Comparing the residence time distribution(RTD)curves at different inclination angles,the proportion of plug flow and dead zone is smaller at 0°,the proportion of total mixed flow is larger,and the flow is the most ideal.The difference between the proportions of each area at 4° and 8° is small.In order to further optimize the flow field,a retaining wall can be set in the butterfly tundish. |
PDF Full Text Request