中间包钢液流动行为的数值模拟及控流装置优化

针对某钢厂四流大方坯连铸过程中铸坯夹杂物含量较高、各流流动状态不一致等问题,本文提出了关于中间包内控流装置(坝高和导流孔结构)的改进方案,采用数值模拟方法对比研究了不同方案下中间包钢液的流场及停留时间分布(RTD)等特征。结果表明,与原型中间包相比,适当增加坝高及下层导流孔的上倾角度,有利于改善中间包钢液的流动特性,各流之间的均匀性明显提高,钢液在中间包内的停留时间有所延长,死区体积分数下降,有效减弱了中间包短路流,中间包冶金功能得到改善;控流装置最佳参数为:坝高300 mm,上层和下层导流孔角度分别为20°和45°,此时对应的钢液在中间包内的平均停留时间为210 s,死区体积分数仅为13.2%。

Numerical simulation of the flow behavior of molten-steel in tundish and optimization of flow control device

To solve the problem of high percentage of billet inclusions and inconsistent flow state during a four-stream continuous casting process in a domestic steel plant, this paper proposes some improvement schemes regarding the flow control device of tundish (dam height and diversion hole structure). The flow field, residence time distribution (RTD) characteristics of molten-steel in tundish under different schemes were comparatively investigated by numerical simulation approach. The results show that compared with the prototype tundish, proper increase of dam height and upward dip angle of the lower diversion hole are beneficial to the improvement of flow characteristics of molten-steel in tundish, and the uniformity of each stream is significantly improved; meanwhile, the residence time of molten-steel in tundish is extended, the volume fraction of dead zone decreases, and the phenomenon of short circuit flow in tundish is eliminated. The metallurgical function of the tundish is therefore improved. The optimal parameters of this flow control device are dam height at 300 mm, diversion hole angles of upper and lower layer at 20° and 45°, respectively. The corresponding average residence time of molten-steel in this tundish is 210 s, and the volume fraction of the dead zone is only 132%.