Numerical Simulation Of Electro-magnetic Flow Control Phenomenon In A Tundish

As the middle link of steel-making process,tundish plays an important role as a connecting link between the preceding and the following,which has a direct impact on the quality of billet.It's an extensive popularity to use the flow control device to improve the flow behavior of molten steel,which promotes the removal of non-metallic inclusions in the tundish.Dam,weir and turbulence inhibitor are some of the devices mentioned above.Although these traditional device can control the flow of molten steel and improve its cleanliness,they take up the effective volume of the tundish and reduce the mean residence time of the liquid steel in the tundish.Worse still,the liquid steel scours the refractory material,which results in the secondary pollution of the molten steel.The non-contact control technology of electromagnetic field can eliminate the above disadvantages.This paper studies the application of electromagnetic field to control the flow of molten steel in tundish,investigates the influence of different parameters on the electromagnetic flow control device,and obtains the optimal parameters of the electromagnetic flow control device,which is of important guiding significance to the mature application.In this paper,a three-dimensional unsteady magnetic hydrodynamics(MHD)model was developed to study the new type tundish.Simulation was performed to study the flow behavior and heat transfer of liquid steel with magnetic field intensity,pole width and pole height as variable by mean of commercial fluent software.Then,the unsteady transport equation was solved on base of steady flow field,and the concentration variation was monitored at the exit of the tundish to obtain the residence time distribution curve.What's more,a further analysis of the flow behavior was done based on the RTD curve.Finally,the flow behavior of traditional dam with that of the electromagnetic dam was compared.The results are concluded as follows:When applying steady magnetic field which is perpendicular to the flow direction of molten steel,the electromagnetic force inhibits molten steel flowing along the bottom of tundish,which reduces the short-circuit flow and dead zone,and increases the plug volume.As a result,the mean residence time of molten steel is prolonged effectively,which is beneficial to the removal of inclusions in the tundish.Electromagnetic flow control effect mainly depends on the magnetic field intensity and pole width,namely,electromagnetic inhibition intensity(BW).There is a critical electromagnetic suppression intensity(BWc)according to the analysis of electromagnetic flow control effects and it is 160T·mm in the present study.In this study,in order to optimize the supreme flow control effect,the optimal parameters of electromagnetic control device are as follows:the distance between the center line of the magnetic pole with that of the injection nozzle is 300 mm,with magnetic field intensity is 0.55 T,pole width is 200 mm,and pole height is 550 mm.