铁水脱硫偏心搅拌的模拟研究

Simulation study on the eccentric stirring of hot metal desulfurization

以铁水罐实际尺寸为基础,按一定比例建立物理模型,对KR法脱硫偏心搅拌进行物理模拟。利用CFD软件,结合VOF多相流模型、标准k-?湍流模型和多重参考系法(MRF)对偏心搅拌铁水脱硫过程进行数值模拟。研究发现,偏心搅拌时漩涡形状呈倒锥形,漩涡深度极大值位于搅拌槽中心位置。搅拌轴距侧壁较近处流体运动强烈,且沿上下两个方向运动;较远处流体运动缓慢,搅拌桨末端流体平均速度约为较远处的2倍。偏心搅拌能改变搅拌器底部流体运动状态,减少“死区”。当搅拌转速由120 r/min增加到200 r/min时,流体平均速度约增加68%,高速流体体积占比略有降低,从60.4%降至57.9%。偏心搅拌易于在工业上实现,转速增加有利于脱硫剂的扩散,但最佳转速应考虑经济性与安全性。

Based on the actual size of molten iron tank, a physical model was proportionally established to simulate the eccentric stirring desulfurization using KR method. Numerical simulation was made to simulate the desulfurization process of hot metal with eccentric stirring by VOF multiphase flow model,standard k-? turbulence model and Multiple Reference Frame method(MRF) using CFD software. It is found that the vortex shape is irregular during the eccentric stirring process, and the maximum vortex depth is located in the center of the mixer. Fluid moves strongly near the agitator wall, and flows along the upper and lower directions. Fluid in the far side moves slowly, and the average fluid velocity in the end side of blade is about twice that in the far side. Eccentric stirring can change the motion state of fluid at the bottom of the mixer and reduce the "dead zone". When the stirring speed increases from 120r/min to 200 r/min, the average fluid speed increases by about 68%, and the volume proportion of highspeed fluid decreases slightly, from 60.4% to 57.9%. Eccentric stirring is easy to be realized in industry,and the increase of speed is beneficial to the diffusion of desulfurizer, however, the economy and safety should be considered for optimum speed.