固定功率下铁水搅拌喷吹脱硫桨的直径与转速优化研究

Study on optimization of impeller diameter and rotation speed of hot metal stirring and injection desulfurization under certain power

针对加搅拌桨复合喷吹镁基脱硫剂进行铁水脱硫的方式,搅拌桨直径与转速的增加都能使镁气泡细微化、弥散化,降低弱气流区,达到提高镁利用率和深脱硫稳定性的目的。但是在功率一定的条件下,搅拌桨直径与搅拌转速不能同时增加,因此,采用物理模拟与数值模拟相结合的方式,研究讨论了在最大功率一定的条件下,如何优化搅拌桨直径和转速以提高脱硫效率。研究表明,在搅拌功率一定时,提高搅拌桨转速、降低搅拌桨直径,熔池搅拌性能增强,气泡与搅拌桨更容易碰撞、被甩出,提高气泡细微化、弥散化程度,熔池混匀时间、气含率、气泡尺寸与分布、传质系数与镁利用率达到更好的水平。但当转速增加到一定程度后,会因搅拌桨直径过小,失去搅拌桨的作用,无法有效提高搅拌性能,增大熔池弱气流区,研究表明转速为90 r/min时效果最佳。换言之,在相同功率、搅拌桨直径不过小的条件下,高转速小直径的搅拌桨比低转速大直径的搅拌桨具有更好的搅拌混匀和反应效果。

For the way of hot metal desulfurization by magnesium based desulfurizer injection combined with impeller, the increase of impeller diameter and speed can make magnesium bubbles fine and disperse, reduce the weak air area, which can improve the utilization rate of magnesium and the stability of deep desulfurization. However, under the condition of a certain power, the impeller diameter and rotation speed cannot be increased at the same time. In this paper, physical simulation and numerical simulation are used to study how to change the diameter and speed of the stirring blade to improve desulfurization efficiency under the condition of a certain maximum power. The research shows that when the power is constant, increasing the rotating speed and reducing the diameter of the stirring paddle will enhance the stirring performance of the molten pool, make it easier for bubbles to collide with the stirring paddle and be thrown out, improve the fineness and dispersion of bubbles, and achieve a better level in the mixing time of the molten pool, gas holdup, bubble size and distribution, mass transfer coefficient and Mg utilization. However, when the rotating speed increases to a certain extent, the function of the impeller will be lost due to the small diameter of the impeller, which cannot effectively improve the mixing performance and increase the weak airflow area of the molten pool. The research shows that the effect is the best when the speed at 90 r/min. In other words, under the same power and appropriate impeller diameter, the impeller with high speed and small diameter has better mixing and reaction effect than the impeller with low speed and large diameter.