长水口浇注位置对中间包使用寿命及钢水质量的影响
Influences of long nozzle pouring position on tundish service life and molten steel quality
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摘要: 中间包是连铸工序的核心设备,起到稳定供给钢液、均衡钢液成分与温度、去除夹杂物等作用,其控流装置易受高温钢液冲刷侵蚀产生熔损,进而造成钢液流场发生变化。本文采用数值模拟结合工业试验的研究手段,将中间包服役周期划分为控流装置有效期(0~40 h)与控流装置完全失效期(40 h 至停包),系统分析不同浇注点位置对各阶段中间包钢液流场的影响规律,并研究其对钢水质量及中间包使用寿命的影响。结果显示,控流装置有效期,浇注点布置在冲击区中心可有效维持钢液流场稳定与均匀,此时死区体积占比最低,为 20.17%,冲击区侵蚀速率最慢,为 6.05 mm/h;控流装置完全熔损后,将浇注点后移 30 mm 可优化流场分布,包内涡流区域面积最小,死区体积占比降至 22.02%,侵蚀速率较中心浇注方案降低 16.86%。工业试验证实,采用复合浇注方案(控流装置有效期采用中心浇注,失效阶段长水口浇注点后移 30 mm)可使中间包使用寿命延长至 80.97 h,且各流钢水元素含量差异相较于其他浇注方式最小。Abstract: As the key equipment in the continuous casting process, the tundish is used to steadily supply molten steel, homogenize the composition and temperature of molten steel, and remove inclusions. Its flow control devices are susceptible to erosion and melting loss induced by scouring of high-temperature molten steel, which further alters the flow field of molten steel. Numerical simulation combined with industrial trials are adopted as research approaches. The service cycle of the tundish is divided into the effective period of flow control devices (0-40 h) and the complete failure period of flow control devices (40 h to tundish shutdown). The influence laws of different pouring point positions on the molten steel flow field inside the tundish at each stage are systematically analyzed, and their effects on molten steel quality and tundish service life are investigated. The obtained results indicate that during the effective period of flow control devices, stable and uniform molten steel flow field can be effectively maintained when the pouring point is arranged at the center of the impact zone. Under this condition, the volume fraction of dead zone reaches the minimum value of 20.17%, and the erosion rate of the impact zone is the lowest at 6.05 mm/h. After the complete melting loss of flow control devices, the distribution of flow field can be optimized when the pouring point is moved backward by 30 mm. The area of vortex region inside the tundish is minimized, the volume fraction of dead zone is reduced to 22.02%, and the erosion rate is decreased by 16.86% compared with the central pouring scheme. Verified by industrial trials, the composite pouring scheme (central pouring is applied during the effective period of flow control devices, and the pouring point of the long nozzle is moved backward by 30 mm in the failure stage) can extend the service life of the tundish to 80.97 h. Meanwhile, the differences in element contents of molten steel among each strand are smaller than those under other pouring modes.
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