溢流式超重力净化反应器内夹杂物运动行为的数值模拟研究

Numerical simulation of inclusion movement behavior in an overflow super gravity purification reactor

  • 摘要: 提出一种全新的溢流式超重力净化反应器工业设计,以实现铝熔体与夹杂物的连续分离,为铝熔体超重力净化新工艺的实施建立工艺技术原型。利用FLUENT建立旋转模型,选用VOF模型研究不同重力系数及铝熔体温度条件下熔体内部压力场特征,在此基础上采用DPM离散相模型研究夹杂物的分离规律。结果表明,铝熔体内部存在沿超重力方向递增的压力梯度,且同一位置的压力值随着重力系数的增加而增大,当重力系数G=500时,贴壁处铝熔体的压力值为5.75×105 Pa。铝熔体中Al2O3夹杂物(18 μm)分离效率随着重力系数的增大而增加,当重力系数G=500时,夹杂颗粒的分离效率达到100%。在超重力场G=48中,随着铝熔体温度的升高,铝熔体内Al2O3夹杂物(18 μm)的分离效果略微提高,当T=1 173 K时,夹杂物的分离效率达99.05%;不同种类夹杂物与铝熔体之间的密度差越大,夹杂物的分离效果越显著,夹杂物密度为3 970 kg/m3时,夹杂物的分离效率达97.73%;夹杂物的去除效果随着粒子尺寸的增大十分显著,当粒子尺寸≥50 μm时,夹杂物的分离效率为100%。

     

    Abstract: An industrial design of an overflow supergravity purification reactor was proposed to achieve continuous separation of aluminum melt and inclusions and to establish a process technology prototype for the implementation of a new process for aluminum melt supergravity purification. The rotation model was established by FLUENT, and the characteristics of the pressure field in the melt were simulated through the VOF model under different gravity coefficients and temperatures, with the DPM discrete phase model used to study the separation law of inclusions on this basis. The results indicated that an increasing pressure gradient existed along the direction of supergravity inside the aluminum melt, and the pressure value at the same position increased with increasing gravity coefficient. The pressure value of the aluminum melt near the wall was 5.75×105 Pa under supergravity with G=500. The separation efficiency of Al2O3 inclusions (18 μm) in aluminum melt increased with increasing gravity coefficient, and the separation efficiency of inclusion particles reached 100% at G=500. In the supergravity field with G=48, as the temperature of the aluminum melt increased, the separation efficiency of Al2O3 inclusions (18 μm) in the aluminum melt was slightly improved. At 1 173 K, the separation efficiency of the inclusions reached 99.05%. The greater the density difference between the inclusions and aluminum melt, the more significant the separation effect of inclusions. When the density of inclusions was 3 970 kg/m3, their separation efficiency reached 97.73%. The separation effect of those inclusions was very significant as the particle size increased. When the particle size was over 50 μm, their separation efficiency was as high as 100%.

     

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