浇铸参数对结晶器液面波动影响及其工业应用

 板坯连铸结晶器液面的波动行为是结晶器内钢液流动、结晶器自身振动以及辊子挤压铸坯内部未凝固的钢液造成液面波动综合作用的结果。结晶器液位波动的稳定性对板坯连铸过程的卷渣行为有直接影响。在工业板坯连铸生产实践中,一般在结晶器某一区域(比如结晶器中部)利用放射源或涡流传感器检测液位波动来代表该工况下的整体波动水平。利用三维气液两相流动的数学模型研究了浇铸参数对结晶器液位轮廓的影响,浇铸参数包括拉速、吹氩流量、浸入式水口出口角度和浇铸断面。研究结果表明,结晶器不同宽度位置的波动幅值差异较大,且与工艺参数密切相关。液面的波峰与波谷之差随着拉速的增加在窄面附近逐渐增大,随着吹氩流量的增加在水口附近逐渐增大。在水口出口角度15°条件下,水口和窄面附近的液位波动均较大,而在水口出口角度45°条件下,仅在水口附近存在较大的液位波动。研究结果表明,使用板坯连铸常规的15°浸入式水口,当铸坯宽度大于800 mm时,结晶器液面检测需要在水口和窄面附近同时布置液位检测设备,以便更全面反应结晶器的真实液面行为,使液面波动对轧板表面质量指导性增强,有效提高连铸工艺的控制水平。如使用45°浸入式水口可以继续沿用原有的液位检测布置。

Influence of casting parameters on level fluctuations and its industrial application

The level fluctuations behavior of the molten steel in the steel slab continuous casting mold is the result of the combined effect of the molten steel flow in the mold,the mold itself vibration,and the fluctuation of the molten steel in the slab when rollers squeeze the slab. The stability of level fluctuations of the mold has a great effect on the behavior of slag entrainment in the continuous casting slab process. In industrial practice of steel slab continuous casting,the level fluctuations is detected in a certain zone of the top surface (such as the middle of the mold width direction) using a radioactive source or an eddy current sensor to represent the overall level fluctuations. In the current study,the effects of casting parameters on the top surface level profile of the mold were studied through the three-dimensional numerical simulation of the gas-liquid two-phase flow. The casting parameters include casting speed,argon flow rate,out-port angle of submerged entry nozzle(SEN)and mold width. The results show that the fluctuation amplitude at different positions of the top surface of the mold was different,and it changed with the variation of casting parameters. With the increasing of the casting speed and argon flow rate,the difference between the peak and the trough of the top surface level profile increased near the narrow face and the SEN,respectively. When the out-port angle of SEN was 15°,the surface level was higher near the SEN and the narrow face. When the out-port angle of SEN was 45°,large surface level was only observed near the SEN. The results show that it was necessary to arrange the level detection equipment near the SEN and the narrow face for mold level detection when using the conventional SEN with 15° out-port angle and the mold width was larger than 800 mm,ensuring more fully reflected the real behavior of level fluctuations of the mold,which can enhance the guidance of the surface quality of the rolled coils and effectively improve the control level of the continuous casting process. When using the SEN with 45° out-port angle,the arrangement of the original level detection remained unchanged.