椭圆钢包内部流场优化与夹杂物去除分析

Flow field optimization and analysis on inclusion removal in elliptical ladle

为了提高某厂实际生产过程中夹杂物的去除效率,以某厂220 t椭圆形钢包为原型,在相似原理的基础上建立了相似比为1∶7的水模型,分析了常规的墨水示踪剂传输过程、盐水示踪剂的混匀、渣眼面积所占比例等过程和参数,并创新地采用粒子图像测速(Particle Image Velocimetry,PIV)技术研究了油层存在时水模型中的流速变化。同时进行了工业试验,分析不同方案中夹杂物数量密度的变化规律。综合探究了3种方案钢液的流场、混匀过程以及夹杂物去除情况。研究结果表明,从长轴一侧AB孔进行流量为150 L/min的等流量吹气时(方案1),其示踪剂传输过程与偏心单孔吹气情况类似,即钢液通过靠近表面的强循环流进行混匀,且混匀时间为所有方案最低;而其两孔形成的渣眼发生聚合,渣眼面积为所有方案最大。当中心对称呈180°夹角布置的AC孔以150 L/min等流量吹气时(方案2),靠近表面钢液的水平流动有所减弱,钢包整体流速下降,但渣眼面积所占比例依然较高。对于AC孔分别以50、100 L/min差流量弱吹时(方案3),渣眼面积比例大幅度降低,减弱了钢液的二次氧化。因受表面渣层(油层)影响,靠近表面钢液流动有所增强,有利于夹杂物的去除。利用工业试验对比了方案1和方案3,发现相比方案1,延长方案3的软吹时间可明显减少10μm以上夹杂物数量。综上,钢包内钢液混匀和去除夹杂物的效果并不能兼得,还需深入研究。

To improve the removal efficiency of inclusions in the actual production process of a plant,based on the similarity principle,a water model with scale factor of 1∶7 was established for a 220 t elliptical ladle.In addition to the conventional research focus on ink tracer transport process,salt solution tracer mixing and slag eye ratio,an innovative research was also carried out by Particle Image Velocimetry(PIV)technology on the flow velocity measurement in water models in the presence of oil layers.In industrial experiments,the changes of inclusions quantity in different schemes were analyzed.The flow field,mixing and inclusion removal of three schemes were comprehensively investigated.For blowing at a equal flow rate of 150 L/min from the A and B plugs which located on one side along the long axis(scheme 1),the tracer transport process is similar to that of eccentric single plug blowing,i.e.mixing is carried out through the strong circulating flow near the surface,and the mixing time is the lowest among all schemes.However,the slag eyes is formed by the two plumes aggregate,and the slag eye area is the largest among all schemes.For blowing at A and C plugs which arranged at 180°angle from the symmetrical center,when the gas flow rate are equal,i.e.150 L/min(scheme 2),the horizontal flow near the surface is weakened,and the overall flow velocity of the ladle decreases,but the proportion of slag eye area is still relatively high.For the same A and C plugs,when the gas flow rate are weak and differential,i.e.50 and 100 L/min(scheme 3),slag eye area is significantly reduced,which can reduce the secondary oxidation.Due to the influence of surface slag layer(oil layer),the flow near the surface is enhanced,which is conducive to the removal of inclusions.In industrial experiments,scheme 1 and scheme 3 were investigated.Compared to scheme 1,extending the soft stirring time of scheme 3 can significantly reduce the inclusions which is larger than 10μm.In summary,the function of mixing and removal of inclusions in the ladle cannot be achieved simultaneously,and further research is required.