废钢对转炉熔池流体流动影响研究

Influence of scrap on bath flow characteristics of converter

通过物理模拟和数值模拟,研究某钢厂250吨转炉中废钢集中分布时熔池特征,以及废钢对转炉熔池流体流动的影响。结果表明,底吹流量为40 L/min时,加入10, 20, 40, 60 t废钢的熔池混匀时间相比无废钢时分别上升21.16%, 63.70%, 87.02%和217.03%。底吹气量较小时(<40 L/min),熔池混匀时间随底吹流量增大而减小,过高的底吹流量对熔池搅拌的贡献降低,反而可能造成熔池混匀时间增加,表明过量的底吹流量将会对熔池混匀产生不利的影响。随着废钢量增加,底吹形成的气液两相区开始向炉壁处偏移。当底吹气量50 L/min时,气液两相区最大速度由0.24 m/s增至0.40 m/s。随着废钢量增加,熔池低速区体积比逐步减小,当加入40 t废钢时,低速区体积比减小89.46%。熔池中随底吹气量增大,熔池获得动能增加,但气体能量利用率降低。熔池中废钢量为60 t,底吹气量增至25, 40和50 L/min时,底吹气体能量利用率比15 L/min时分别下降2.98%, 6.27%和8.68%。当熔池中加入废钢时,随废钢量增加,气体能量利用率上升。底吹气量25L/min,熔池中废钢加入量为10和60t,气体能量利用率分别增加2.48%和41.41%。废钢量较大时,底吹气体利用率出现较大幅度上升。

The current study focus on the flow characteristics and the effects of scrap on the bath flow with the help of mathematical model which is built based on the physical model of a 250 t converter. The results showed that the mixing time was a decreasing function of the flow rate of bottom blowing when the flow rate was relatively low(<40 L/min). On the contrary, excessive high flow rate of the bottom blowing would not contribute on the decreasing of the mixing time which demonstrated that increasing flow rate was not favorable for decreasing the mixing time if the flow rate was higher than the critical value. With increasing the scrap volume, the plume formed in the bottom blowing moved towards to the bath wall. Meanwhile, the maximum velocity of the plume increased from 0.24 m/s to 0.40 m/s when the bottom flow rate was 50 L/min compared to the flow rate of 15 L/min. The kinetic energy of the bath was increased while the volume ratio of the low-velocity zone was decreased when the scrap volume increased. The volume ratio of the low-velocity zone can be decreased 89.46% when 40 t scrap was added into the bath compared to that of no scrap addition. Specifically, compared to that of 15 L/min when 60 t scrap was added, the transfer indexes decreased 2.98%, 6.27% and 8.68% when the bottom flow rate increased to 25, 40 and 50 L/min, respectively. The effects of the scrap volume on the energy transfer index was also investigated and the results showed that increasing the scrap volume was benefit to increase the energy transfer index for the bath and large volume of the scrap greatly increased the energy transfer index. When the bottom flow rate was 25 L/min, the energy transfer index increased 2.48% and 41.41% when the scrap volume increased to 10 and 60 t, respectively.