Numerical Simulation of the Effects of Horizontal and Vertical EMBr on Jet Flow and Mold Level Fluctuation in Continuous
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ting process, especially under the condition of high casting speed, increased flow rate of the liquid steel at the outlet of submerged entry nozzle (SEN) can easily cause disturbances at the steel/slag interface at the top of the mold. This phenomenon may cause mold flux entrapment and result in entrainment of inclusions and bubbles into the liquid steel, which are entrapped in the newly formed steel shell, thus affecting the slab quality.[1,2] Therefore, effectively controlling
LIN XU, ENGANG WANG, ANYUAN DEN, and XIUJIE XU are with the Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, No. 3-11, Wenhua Road, Shenyang 110004, P.R. China and also with the School of Metallurgy, Northeastern University, Shenyang 110004, P.R. China. Contact e-mail: [email protected] CHRISTIAN KARCHER is with the Institute of Thermodynamics and Fluid Mechanics, Technische Universita¨t Ilmenau, P.O. Box 100565, Ilmenau 98684, Germany. Manuscript submitted December 15, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
level fluctuations in the mold is key to producing high quality steel slabs. Equipment which controls fluid flow in the mold through the application of static magnetic fields is referred to as an electromagnetic brake (EMBr). The design of EMBrs is continuously being improved, and they have been demonstrated to be effective in reducing the potential for liquid steel breakouts from the strand shell, and decreasing slab and final product surface defects.[3–6] Up to now it has been developed into three typical types: Local EMBr,[3,4] Ruler-EMBr[5–9] and flow control mold (FC-Mold) EMBr.[10] Local EMBr has a characteristic that two separate magnets are located near the SEN ports, which is mainly used to suppress molten steel velocity from the nozzle and prevent mold flux entrapment. Ruler-EMBr utilizes one pair of magnets, which covers the entire wide faces of the mold, with the aim to stabilize the meniscus velocity and prevent mold flux entrapment. To better control meniscus fluctuations and molten steel flow behavior in the mold, a third-generation electromagnetic brake (FC-Mold EMBr) was proposed. FC-Mold EMBr
consists of two pairs of magnets across each wide face. One is located on the meniscus of the mold, and the other is located below the SEN port. Currently, there are two widely used EMBr devices: Ruler-EMBr and FC-Mold EMBr.[11,12] It was found that, in the slab continuous casting process, the braking effects of Ruler-EMBr on the surface velocity and level fluctuation are not significant and usually Ruler-EMBr was u nable to suppress mold flux entrapment effectively.[6] Compared to Ruler-EMBr, FC-mold is good at controlling meniscus velocity and level fluctuation. However, it’s not applicable for the continuous casting of thin slabs due to large volume, heavy weight and complicated structure. Therefore, on the basis of understanding the characteristics of the existing EMBr, a new type of EMBr, named vertical electromagnetic brake (V-EMBr) was proposed by our research group in
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