Mathematical Modeling of Iron and Steel Making Processes. Effect of Magnetic Field Conditions on the Electromagnetic Braking Efficiency.

Abstract

Effect of different types of in-mold electromagnetic brake (EMBr) technique, which forms a local magnetic field and a level magnetic field in the width direction of a mold, on the fluid flow phenomena in the strand pool was examined. A mercury model experiment revealed that the level magnetic field developed a pluglike flow in the strand pool, of which flow could not be obtained by the local magnetic field. Surface velocity near the meniscus could be stably controlled with the level magnetic field, while in the case of the local magnetic field, this surface velocity was greatly affected by the nozzle condition. Numerical analysis clarified the characteristics in the distribution of an induced electric current density and Lorentz force, and explained the flow behavior with the local and level magnetic fields, respectively.KEY WORDS: continuous casting; fluid flow; electromagnetic brake (EMBr); mercury model experiment; numerical analysis; magnetohydrodynamics (MHD). trolled at a constant level, according to the principle of the U-shaped tube. The mercury then is pumped up into the tundish above the strand pool. From there, it is discharged again into the pool through a pipe, which serves as an immersion nozzle. In the lower part of nozzle, the acrylic pipe is utilized for electric insulation. The flow rate of the mercury through the immersion nozzle is adjusted by a stopper in the tundish. Two types of DC magnets were placed around the vessel to investigate the effect of the magnetic field conditions on the flow. One DC magnet type forms a DC magnetic field partially crossing the broad face of the mold. The other one forms a level magnetic flux density in the width direction of the pool. The resulting flow of mercury then was used to predict the molten steel flow. The distribution of magnetic flux density which each DC magnet forms, was measured without mercury circulation. Figures 3(a) and 3(b) show the vertical and horizontal distribution of the magnetic flux density throughout the pool of mercury in the case of the local magnetic field and the level magnetic field, respectively. Table 1 gives the experimental conditions adopted in the mercury model experiment. The total amount of mercury in the pool was about 2 tons. The level magnetic field's center was 135 mm below the meniscus. The local magnetic field's center was 150 mm below the meniscus and 150 mm from the center of the pool. In addition, the effect of an angle of nozzle port, 15 degrees downward and 45 degrees downward respectively, on the fluid flow was examined. These experiments will be referred to as nozzle condition A and nozzle condition B, respectively, throughout the remainder of this paper. Figure 4 shows the relationship between the discharged flow and DC magnet in each magnetic field condition. With the local magnetic field, the crossing length in the magnetic area is longer in the nozzle condition A than the one in the nozzle condition B. With the level magnetic field, in both of the nozzle conditions A and B, the discharged flow directly c...

Large Eddy Simulations of Double-Ruler Electromagnetic Field Effect on Transient Flow During Continuous Casting

“…[8] This set of coupled MHD equations (Eqs. [1]- [5]) is solved by the finite volume method and implemented on a graphics processing unit (GPU) for fast computation in the in-house code CUFLOW. The numerical details of solving these equations with CUFLOW have been discussed in previous studies, [16][17][18][19] and hence, are only briefly described in Section II-F.…”

“…Statically-applied electromagnetic-field (EMF) configurations include local [circular fields on each side of the Submerged Entry Nozzle (SEN)], [1][2][3][4][5] single-ruler (a rectangular field across the entire mold width), [5,6] and double-ruler [6][7][8][9] (two rulershaped fields, with one positioned across the mold near the meniscus and the other one aligned through or below the nozzle ports). When the EMF coil currents are adjusted to produce equal peak field strengths, this double-ruler configuration is commercially known as ''Flow-Control-Mold'' or ''FC-Mold'' ElectroMagnetic Braking or ''EMBr.''…”

Transient Fluid Flow during Steady Continuous Casting of Steel Slabs: Part II. Effect of Double-Ruler Electro-Magnetic Braking

“…[1][2][3][4][5][6][7][8][9][10][11] For example, Cukierski and Thomas reported that local EMBr usually decreases the surface velocity, depending on the submergence depth of the Submerged Entry Nozzle (SEN). 8) Wang and Zhang investigated the effects of local EMBr on the fluid flow, heat transfer, and transport of argon bubbles and inclusions in the mold.…”

Mathematical Modeling of Iron and Steel Making Processes. Optimum Magnetic Flux Density in Quality Control of Casts with Level DC Magnetic Field in Continuous Casting Mold.

“…Of these efforts, utilization of direct current (DC) magnetic fields started with a localized electromagnetic brake 2) aimed at reducing the velocity of the outlet stream from the submerged entry nozzle (SEN) and is now changing to a full-width electromagnetic brake 3,4) as a nextgeneration electromagnetic brake with superior control capability.…”

“…[4][5][6][7] The flow of molten steel in the mold is controlled by changing the downward flow velocity and penetration depth in the mold and the flow velocity and temperature of molten steel in the meniscus through application of the LMF electromagnetic brake. 5) Consequently, the length of intermixed compositions formed during sequence casting of dissimilar grades of steels is shortened, 6) and the number of nonmetallic inclusions in the cast slabs is reduced.…”