市政污泥机械脱水前多采用化学调理,调理装置搅拌过程中的流场分布直接影响调理效果。采用多重参考系-流体体积模型对实验室污泥调理罐(内径为40 cm)的流场特性进行计算流体力学(computational fluid dynamics,CFD)模拟研究,验证了实验室调理罐模型气液两相分布情况。实验室调理罐的模拟结果表明:单层直桨叶调理罐的搅拌桨直径与调理罐内径比优化值为1:1.75,挡流板宽度与调理罐内径比优化值为1:20,可有效消除流体旋涡,增强湍动作用。在此基础上,对中试调理罐(内径为110 cm)的流场特性进行模拟并与实际测量值校验。该研究采用的多重参考系-流体体积模型可为同类污泥调理罐设计与优化提供参考。
Chemical conditioning is commonly used before the mechanically dewatering process for sewage sludge. The flow field distribution of conditioning tank has a significant effect on conditioning when paddles are operating. Moving reference frame-volume of fluid model was used for simulating flow field distribution of a sludge conditioning tank with the inner diameter of 40 cm by CFD (computational fluid dynamics) technology, and the gas-liquid two-phase distribution was verified. The results showed that in the single straight blade paddle conditioning tank, the optimium ratio of paddle diameter to tank diameter was 1:1.75 and the optimum ratio of baffle width to tank diameter was 1:20. Under these optimum conditions, the fluid swirl could be effectively eliminated and the turbulent action could be enhanced. Furthermore, the flow field distribution simulation was conducted for pilot-scale conditioning tank with the inner diameter of 110 cm and the simulation results were compared with test results. Moving reference frame-volume of fluid model used in this study can provide references for design and optimization of similar sludge conditioning tank.