板坯连铸结晶器保护渣卷渣及其影响因素的研究

Water Modeling Study on Factors Affecting Mold Powder Entrapment in Slab Continuous Casting

对板坯连铸结晶器保护渣卷渣进行的水力学模拟研究结果表明,主要有三种类型的卷渣,即窄边附近的剪切卷渣、浸入式水口附近的旋涡卷渣和水口吹入的氩气泡上浮冲击钢渣界面引起的卷渣。拉速增加、减少浸入式水口浸入深度、减小水口出口倾角和增加吹入的Ar流量均会加大表面流速和液面波动,增大结晶器内卷渣的倾向,而其中拉速增加对卷渣的影响最大。当结晶器宽度为1 900 mm、采用1.4 m/min的拉速时,选择向下25°的水口出口角度2、50 mm的水口浸入深度和10 L/min的Ar流量可将板坯结晶器内流场的表面流速和液面波动控制在合理的范围内,从而减小和避免结晶器内卷渣。

It was found by water modeling study that there are mainly three types of mold powder entrapment in slab continuous casting, i. e. , the entrapment caused by the shearing flow near the narrow face of the mold, the entrapment caused by vortexes in regions around the submerged entry nozzle （SEN） and the entrapment caused by the disturbing action of the Ar bubbles on the interface between liquid steel and mold powder. Both the velocity of the surface flow and the level fluctuation in the mold are enlarged with increasing the casting speed, reducing the submerged depth of SEN, decreasing the downward angles of the nozzle outlets and increasing the Ar flow rate, of all which increase the tendency of the mold powder entrapment. Among the 4 above mentioned factors, increasing casting speed has the largest effect on mold powder entrapment. It was found that, when 1.4 m/min of casting speed was used for slab of 1 900 mm width, the velocity of surface flow and the level fluctuation in the mold could be well controlled to prevent and reduce the mold powder entrapment when 25°of the downward angles of the SEN outlets, 250 mm of submerged depth of SEN and 10 L/min of Ar flow rate were used in the experiment.