Numerical calculation of fluid flow in a continuous casting tundish
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INTRODUCTION
IN the
past several decades, continuous casting of steels has emerged as a widely used technology in modern steel plants. Since the improved yield and operating cost benefits of the continuous casting process are now well recognized, the process will play an increasingly important role in the production schedule of most steelmaking companies in the foreseeable future. A schematic diagram of the continuous casting tundish is shown in Figure 1. An important operating problem in continuous casting is the deposition of nonmetallic materials in tundish nozzles resulting in a reduction in the metal pouring rate through the nozzles. This reduction in the metal flow rate from the tundish to the mold is a serious problem in maintaining a steady production rate and may also result in poor surface quality of the product. In extreme cases, the buildup of the oxide products continues until complete blockage of the nozzle occurs, thereby disrupting the operating schedule. The mechanisms of nozzle blockage have been discussed by Duderstadt et al. ~ and also in detail by Singh.: Singh established that the primary reason for the nozzle blockage was the alumina deposition. Schwerdtfeger 3 found that the inclusions deposited at the nozzle orifice did not form in situ. The buildup of corundum in the continuous casting nozzle was investigated using a radioactive isotope by Shevchenko. 4 0 n o et al. 5 found that the deposition was a mixture of A1203, SiO2, Fe203, MnO, and other deoxidation products. The importance of the reoxidation of steel in the continuous casting process was emphasized by several investigators. 6-~~As a result of these studies, it is now generally accepted that the nozzle blockage is caused by the deposition of relatively fine deoxidation products and somewhat coarser reoxidation products. Earlier efforts to alleviate this problem can be placed into several categories. Significant efforts were made in preventing the reoxidation of steel by stream protection 1~ and also in improving designs of the tundish nozzles to minimize deposition. ~'2'~2 Other efforts to alleviate this problem included modification of the deoxidation process to acquire a T DEBROY ~s Associate Professor of Metallurgy at The Pennsyl,~ama State University, 212 Steldle Braiding, Umversity Park, PA 16802. J. A, SYCHTERZ, formerly wxth The Pennsylvama State Umverstty, is now with the United States Navy assigned to the Newport News Shipbuilding and Drydock Company. Manuscript submitted December 4, 1984. METALLURGICAL TRANSACTIONS B
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Fig. 1 - - A schemaUc diagram of a continuous casting tundish.
liquid deoxidation product, 6.27,28injection of A1 wire downstream of the tundish nozzle to reduce deposition, t5 refining of steel using ceramic filters, ~6 and use of "atmospherecontrolled" tundishes. J7 Although the earlier work was useful in highlighting several aspects of this multifaceted problem, the deposition of the nonmetallic particles is still a serious problem in the industry today. The nonmetallic particles are tr
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