基于CFD-PBM耦合方法的栅条絮凝池内颗粒聚并行为模拟

NUMERICAL SIMULATION OF PARTICLE AGGREGATION IN GRID FLOCCULATION TANK BASED ON CFD-PBM

为探究絮凝池内部颗粒聚并行为的影响因素,采用群体平衡模型(PBM)模拟颗粒聚并行为,通过CFD-PBM耦合方法,研究了絮凝颗粒初始平均粒径和絮凝颗粒体积分数对栅条絮凝池内部颗粒聚并行为的影响,提出了颗粒平均粒径增长率指标来表征CFD-PBM耦合方法下絮凝池内部絮凝效果。结果表明:1)当进口颗粒体积分数为0.1时,随着絮凝颗粒初始平均粒径由10μm增长到76μm,出口处粒径由117.54μm增长到154.82μm,但颗粒平均粒径增长率由1075.4%迅速降低至103.7%;2)在进口颗粒初始粒径为40μm时,随着颗粒体积分数由0.05增长至0.2,出口位置颗粒粒径由127.16μm增加至155.74μm,而平均粒径增长率也随之由208.7%增加至289.4%;3)从整体上来看,当颗粒体积分数从0.05增加到0.1时,平均粒径增长率的变化最快,絮凝效果的提升最为显著。研究结果对于栅条絮凝池的结构设计指导和絮凝效果评价具有重要意义。

In order to explore the influencing factors of particle aggregation behavior in the flocculation tank,the population balance model(PBM)was used to simulate the particle aggregation behavior in this paper.By means of CFD-PBM coupling method,the effects of initial average particle size and volume fraction of flocculated particles on particle aggregation behavior in a grid flocculation tank were studied.An index of average particle size growth rate was proposed to characterize the flocculation effect inside the flocculation tank under the CFD-PBM coupling method.The results showed that:1)when the inlet particle volume fraction was 0.1,as the initial average particle size of flocculated particles increased from 10μm to 76μm,the particle size at the outlet increased from 117.54μm to 154.82μm,but the average particle size growth rate decreased from 1075.4% to 103.7%;2)when the initial particle size of the inlet particles was 40μm,as the particle volume fraction increased from 0.05 to 0.2,the particle size at the outlet position increased from 127.16μm to 155.74μm,and the average particle size growth rate also increased from 208.7% to 289.4%;3)overall,within the particle volume fraction range of 0.05 to 0.1,the average particle size growth rate was the highest,and the flocculation effect improved most significantly.