连铸板坯二冷高温区传热均匀性研究与优化

在板坯连铸过程中,二冷区传热的均匀性对铸坯表面与内部质量均有重要的影响。首先对国内某钢厂二冷各区的喷嘴进行了喷淋性能测试,根据各冷却区喷嘴的布局及2 000 mm×250 mm断面包晶桥梁钢板坯连铸生产过程的各区水量分布,建立了铸坯三维凝固传热有限元计算模型,模拟分析了铸坯在二冷区内的动态凝固传热行为。在此基础上,优化调整了连铸二冷高温区的喷嘴布局。结果表明,某钢厂原二冷区喷嘴布局条件下,其高温区的铸坯表面温度沿其横向波动较大。典型生产工艺下,二冷4区出口处的铸坯宽面表面横向温差最大,即距角部313 mm处的宽面表面温度最高为1 073 ℃,而距角部873 mm处的宽面表面温度最低为996 ℃,温差达77 ℃。而当铸坯进入二冷弧形区时,铸坯表面的横向温度分布逐渐趋于均匀。将二冷2区的喷嘴安装高度由距铸坯表面170提升至200 mm、3区和4区的喷嘴安装高度由距铸坯表面200提升至240 mm,可使铸坯在高温区内的表面横向温差最大值降至30 ℃以下,大幅改善铸坯表面温度分布的均匀性。

Study and optimization of uniformity of continuous casting slab heat transfer in high temperature zones of secondary cooling

In the practical slab continuous casting, the uniformity of slab heat transfer in the secondary cooling has an important effect on the surface and internal quality of slab. Firstly, the spray parameters of the nozzles in different cooling zones a steel plant was tested, and a 3D heat transfer finite element model of a slab with 2 000 mm×250 mm section was established according to the layout of the nozzles and the corresponding water amount in each cooling zone for casting bridge steel, simulating and analyzing the dynamic heat transfer behavior of the slab in the secondary cooling zones. Base on these, optimized and adjusted the nozzle layout in the secondary cooling high temperature zones. The results show that the transverse surface temperature of the slab in the high temperature zone fluctuates greatly under the conditions of nozzle layout in the original secondary cold zone of a steel plant. Typical production process, the highest temperature of 1 073 ℃ of slab surface forms at the position of 313 mm away from the corner, the lowest temperature of 996 ℃ forms at 873 mm away from the corner in the exit of No.4 cooling zone, the difference value of the temperature reaches 77 ℃. When the slab enters the arc cooling zones, the transverse surface temperature distribution tends to be uniform gradually. Increasing the installation height of the nozzles of No.2 cooling zone from 170 to 200 mm and the height of the nozzles of No.3 and No.4 cooling zone from 200 to 240 mm from the slab surface, the maximum temperature difference of the slab surface in the high temperature zone would reduce to below 30 ℃. The uniformity of slab surface temperature may greatly improve.