140t铁水包底吹氩混合特性物理模拟研究

Physical simulation of mixing characteristics in 140 t hot metal ladle with argon bottom blowing

针对铁水包底吹搅拌工艺,以某厂140 t铁水包为原型,基于相似原理建立物理模型,探索了合理的混匀时间测定方法,研究了圆底及平底铁水包底吹氩的混匀特性,并考察了气量、透气砖位置及高径比对混匀特性的影响规律。提出一种合理的混匀时间测定方法,即:通过示踪流场找出混匀较慢的几个典型监测位置并测定其混匀时间,将所测数据的最大值作为本方案的混匀时间。研究结果表明:圆底铁水包中心底吹下,随吹气量增大,混匀时间整体呈减小趋势,最佳混匀气量为800 L/min,且混匀时间随高径比增加呈先增大后减小的趋势;中心底吹下,当吹气量小于200 L/min时,圆底铁水包的混匀效果要明显好于平底铁水包,当吹气量超过300 L/min后,平底与圆底铁水包的混匀效果相差不大;就本研究而言,平底铁水包中,随高径比增大,混匀效果最佳底吹位置由中心向0.33R偏移,且0.67R孔底吹的混匀效果始终最差。

For the bottom blowing stirring process of hot metal ladle,a physical model was established based on the similarity principle with a 140 t hot metal ladle of a certain factory as the prototype.A reasonable mixing time measurement method was explored,and the mixing characteristics of argon bottom blowing in round and flat bottom hot metal ladles were studied.The influence of gas flow rate,the position of permeable brick and the height-diameter ratio on the mixing characteristics was investigated.In this paper,a reasonable method for measuring mixing time is proposed.By tracing the flow field,several typical monitoring positions with slow mixing are found and the mixing time is measured.The maximum value of the measured data is used as the mixing time of this scheme.The results show that,under the central bottom blowing of the round-bottom ladle,with the increase of blowing rate,the mixing time decreases on the whole,and 800 L/min is the best mixing rate,and the mixing time increases first and then decreases with the increase of height-diameter ratio.Under the central bottom blowing,when the blowing rate is less than 200 L/min,the mixing effect of the round bottom ladle is significantly better than that of the flat bottom ladle.When the blowing rate exceeds 300 L/min,the mixing effect of the flat bottom ladle and the round bottom ladle is similar.In this study,for flat bottom hot metal ladles,with the increase of height-diameter ratio,the best bottom blowing position of mixing effect shifts from center to 0.33R,and the bottom blowing mixing effect of 0.67R hole is always the worst.