旋流沉砂池除砂废水流场与结构参数优化模拟

NUMERICAL SIMULATION OF FLOW FIELD AND OPTIMIZATION OF STRUCTURE PARAMETERS OF VORTEX GRIT CHAMBER FOR SANDSTONE WASTEWATER TREATMENT

在旋流沉砂池砂石废水处理中,具有复杂流态的高浓度固液两相流问题一直是难以攻克的难题,给工程设计与运行带来很大困难。该文采用分子动理学方法从固液两相流相互作用的微观特性出发,得出合理描述旋流沉砂池内高浓度下颗粒间碰撞项的Eulerian-Eulerian两相流模型。采用滑移网格技术实现了旋流沉砂池桨叶转动区域的模拟。结合西南某水电工程砂石废水处理中的旋流沉砂池流场进行了模拟,并讨论了搅拌桨转速、桨叶位置、叶片数量和叶片角度对旋流沉砂池内水相、颗粒相的影响。结果表明:该水电站砂石处理系统旋流沉砂池的最佳桨叶结构和运行工况为:桨叶转速r=105rap/min,桨叶位置z=592mm,叶片数量为4片,叶片角度为45°。

The problem of high concentration solid-liquid two-phase flow is difficult to overcome because the flow is complex in the vortex grit chamber. It leads to poor engineering design and operation. Eulerian - Eulerian solid-liquid two-phase flow model with the consideration of collision between particles is presented in this paper. The model is gained from the perspective of microscopic interaction between liquid and solid through the molecular kinetic theory and the computational fluid dynamics. Sliding mesh technology is used to simulate the vortex grit chamber in a hydropower sandstone wastewater treatment, Southwest China. The influences of the four factors including rotate speed, distance between the propeller and the base, number of propeller blades and angle of the propeller on the efficiency of the grit removal efficiency are studied. According to the single factor test, the optimal condition for the novel vortex grit chamber is that, the rotate speed of propeller is 105 rap/min, the distance between the propeller and the base is 592mm, the number of propeller blades is 4 and the angle of the propeller is 45°.