卧轮式分级机内流场的“双旋涡”分布特性

The “Double Vortex” Distribution Characteristics of the Flow Field in the Horizontal Turbo Air Classifier

卧轮式分级机内流场的分布规律对物料分级效果至关重要。基于RNG k-ε双方程湍流模型与离散相模型(DPM),对进风口风速为18 m/s,转笼转速分别为3000 r/min、6000 r/min、12000 r/min三种工况下的"双旋涡"分布规律进行研究,探讨"双旋涡"分布特性对卧轮式分级机内流场及分级性能的影响。研究发现:1)卧轮式分级机的进气口方位与转笼转速会影响分级室内水平涡旋的气流偏向,使分级机内呈现不同的"双涡旋"分布特征;2)分级机内流场的稳定均布性会影响"双涡旋"流型的旋进方向,且内旋涡的形成及涡核分布受分级室内的水平旋涡约束。以碳酸钙为物料进行分级实验,结果表明:1)不同工况下分级机流场的稳定均布性差异较大,会造成"双涡旋"分布变化;2)随着转笼转速的增加,切割粒径平均减小28.85μm,粗粉产率平均提高33%,分级精度指数平均降低10.5%。物料分级实验结果与数值模拟结果吻合。研究结果对卧轮式分级机的性能优化和结构设计有一定参考意义。

The distribution characteristics of the flow field in a horizontal turbo air classifier are very important for the grading of materials.The influence of the"double vortex"distribution characteristics on the flow field and grading performance of the horizontal turbo air classifier under 3 different working conditions,i.e.the inlet air speed is 18 m/s and the rotating speed of the rotating cage is 3000 r/min,6000 r/min and 12000 r/min respectively,is studied based on the RNG k-εdouble equation turbulence model and discrete phase model(DPM).The study shows that:1)the inlet position and the rotating speed of the rotating cage of the horizontal turbo air classifier will affect the horizontal vortex flow direction in the classifier room,making the classifier present different"double vortex"distribution characteristics;2)the stable uniformity of the flow field in the horizontal turbo air classifier will affect the vortex direction of the"double vortex",and the formation of the internal vortex and the distribution of the eddy core are constrained by the horizontal vortex in the classifier room.The grading experiment using calcium carbonate as the material shows that:1)the stable uniformity of the flow field of the classifier under different working conditions is quite different,which will cause the"double vortex"distribution change;2)with the increase of the rotating speed of the rotating cage,the cutting particle size decreases by 28.85μm on average,the coarse powder yield increases by 33%on average,and the grading accuracy index decreases by 10.5%on average.The experimental results of material grading agree with the numerical simulation results.The results have reference significance for the performance optimization and structural design of horizontal turbo air classifiers.