钢包钙处理工艺中钙汽化过程的数值模拟

Numerical simulation of calcium vaporization during Ca-treatment process in ladle

根据钙处理过程中汽化速率的变化特点,结合实际喂线工艺参数,将钙处理工艺分为喂线阶段和弱搅静置2个阶段,建立钢包钙汽化过程的数学模型。利用大型商业软件CFX,模拟钙的汽化过程,并研究不同喂线速率对钙收得率的影响。研究结果表明:喂线阶段与弱搅静置阶段钙的实际汽化速率有较大差异;当喂线阶段实际汽化速率与理论气泡上浮速率之间的比例系数k=0.4、弱搅阶段表观速率常数Ke=0.001 2 s-1时,模拟计算的钙质量分数与实验钙质量分数较吻合,从而确立适合模拟的基础参数;当喂线速度为200 m/min时,喂线180 s后,钙在钢中分布极不均匀,经过弱搅静置阶段,即喂线1 000 s后,钢液中钙质量分数均匀分布,平均质量分数为1.86×10^(-5),钙的收得率为23.2%;随着喂线速率的增加,喂线深度随之增加,钙的汽化量减小,收得率增加。

According to the law of calcium vaporization change in calcium treatment and actual data feeding wire process,the vaporization of calcium model was established based on two different calcium vaporization stages, feed wire period and week stirring period. The changing rules of calcium recovery with different feedrates were simulated through CFX.The results show that there are apparently different vaporization velocities between feed wire period and week stirring period. Actual vaporization velocity is proportional to theoretical floatation velocity of calcium bubble. When the proportional coefficient k is 0.4 in the feeding wire process and the apparent rate constant Ke is 0.001 2 s^（-1） in weak stirring stage, this numerical simulation matches actual plant data very well. At 200 m/min of feeding wire rate, the distribution of the mass concentration of calcium is uneven at 180 s after the end of feed wire. However, the calcium distributes equally in melt after week stirring period. The average mass fraction of calcium is 1.86×10^-5 and the recovery of calcium is 23.2%. At some extent, the deepness of feeding wire and the calcium recovery increase with the feeding rate,whereas the vaporization of calcium may increase.