连铸中间包底吹气过程水模型实验研究

以宝钢集团梅山钢厂1台连铸中间包为原型,采用自行设计的吹气装置于底部吹气,用水模型的方法研究了吹气对中间包过程的影响。实验结果表明,底部吹气显著地改变了中间包内的流体流动特征;当不吹气时,通过上挡板下部的液流以层流形式贴近中间包的底部流动,然后从出口直接流出,在中间包的停留时间较短,死区体积较大,不利于夹杂物的去除;吹气以后,上升的气流起到了气幕挡墙的作用,通过上挡板下部的液流,被上升的气流抬起,贴近液面流动;吹气有利于增加平均停留时间,缩小中间包的死区体积,此外,上升的气流对中间包的液流具有一定的清洗作用,有利于夹杂物的去除;吹气用于中间包去夹杂过程,不需要较大气体流量。在气体流量相同时,在水模型实验装置中3个位置吹气对中间包的平均停留时间、中间包的死区体积分数、最短平均停留时间的影响大致相同,但总体上,中间位置的吹气效果要好于其他2个位置的吹气效果。

Water Model Study on Bottom Gas Blowing Process in Continuous Casting Tundish

Bottom gas blowing process in continuous casting tundish was studied with water model, prototype of which is the one in Meishan Iron and Steel Cooperation. Air is blown into the tundish from the bottom with an air-supply equipment, with which tiny and steady bubbles can be produced in tundish. The results show that, without bottom gas blowing, water flowing through the weir flows close to the bottom of tundish bath in a laminar type, and flows out from the outlet directly, so that the average residence time is short and the dead-zone volume fraction is large, which is unfavorable for inclusion removal. With bottom gas blowing, water is uplifted by up-going gas acting as gas baffle, and flows close to the bath surface. Bottom gas blowing is benefit to increasing average residence time and reducing the dead-zone volume fraction. In addition, the ascending gas flow has a role of cleaning, which is in favor of inclusion removal. Inclusions can be removed with a relative small amount of low gas flow rate. It has similar influence of different locations on the average residence time, dead-zone volume fraction and the shortest residence time. But, on the whole, blowing at location in the middle of bath has a better effect.