| The study on molten steel flow in tundish and mold is necessary to guarantee thesmooth operation of continuous casting process and improving the quality ofcontinuous casting strand. The common methods of study on molten steel flow includephysical and mathematical simulation. In the thesis, the influence of different flowcontrol devices on fluid flow in tundish, and different submerged entry nozzles(SENs)and operation process on flow behavior of molten steel in mold were researched bymeans of these two methods according to the operation process of billet/round bloomcontinuous casting tundish and mold in Yanshang steel. In this subject, the flow controldevices in tundish included the retaining wall with holes opening and low retainingwall, the mold SENs included straight through SEN, two side outlet SEN and four sideoutlet SEN, and the cross section of mold were as follow:350mm×500mm,230mm×350mm, Φ350mm and Φ400mm.The flow field of molten steel, flow patterns, temperature distribution andinclusion floating in tundish on condition of different flow control devices wereanalysed by means of physical and mathematical simulation in the thesis. Thecomprehensive analysis of two simulation results were the following: the flow fieldwas improved, dead zone volume was decreased, residence time of molten steel wasincreased, and consisrency of each outflow was enhanced in tundish with retainingwall with holes opening and low retaining wall, which above were helpful to improvestable operation process; the inclusion floating ratio of50μm and below was higherthan other granularities in tundish with low retaining wall，and the inclusion floatingratio of which is higher than retaining wall with holes opening in tundish. The analysisshowed that the low retaining wall of a10could be considered as the optimized flowcontrol device.The three kinds of submerged entry nozzle(SEN) were designed and optimizedbased on physical and mathematical simulation, and the straight through SEN of#1,two side outlet SEN of#5and four side outlet SEN of#9were considered better forthe indices of experiment by anaslysing the influence of nozzle type, inserting depth ofnozzle and casting speed on fluid flow in mold. Because of gas blowing through SENin mold, the influence of gas blowing on flow field and level fluctuation in mold werealso analysed in the thesis. The inserting depth and gas blowing range on condition of different cross sections, kinds of nozzles and casting speed were finally determined inthe thesis. |
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