均质滤料滤池反冲洗数值模拟及优化  

Numerical simulation and optimization of uniform media filter Backwashing in filter

作　　者：许仕荣[1] 安浩颖 黄茂林[2] XU Shirong;AN Haoying;HUANG Maolin(School of Civil Engineering,Hunan University,Changsha 410082,China;China Machinery International Engineering Design and Research Institute Co.,Ltd.,Changsha 410007,China)

机构地区：[1]湖南大学土木工程学院,长沙410082 [2]中机国际工程设计研究院有限责任公司,长沙410007

出　　处：《安全与环境学报》2023年第6期2111-2118,共8页Journal of Safety and Environment

基　　金：中国机械设备工程股份有限公司科技研发基金资助项目(CMEC KJYF 201504)。

摘　　要：为优化均质滤料滤池反冲洗设计参数,减少水量消耗,避免滤料流失,利用Fluent对滤池均质滤料的反冲洗进行三维尺度下的多相流模拟。模拟中选用欧拉欧拉多相流模型及RNG kε湍流模型,引入颗粒流理论探究颗粒间的作用力。通过模拟可得到颗粒轴向速度的分布和滤料环流状况,并以“能形成稳定的环流”为标准,同时综合反冲洗时滤料膨胀率的要求,分别对不同粒径滤料单水冲洗和气水同时冲洗时的冲洗强度进行优化。实验室滤柱试验验证了模拟误差在合理范围之内。模拟结果显示:均质滤料粒径为1.0 mm、1.2 mm、1.4 mm时,单水冲洗适宜的水强度为(qmf+5)L/(s·m^(2)),气水同时冲洗适宜的气强度分别为12.5~15 L/(s·m^(2))、15.0~17.5 L/(s·m^(2))、17.5~20 L/(s·m^(2));气水同时冲洗时滤料表层平均动能远大于单水冲洗时的平均动能,表明气水同时冲洗效果优于单独水洗方式。This paper aims to optimize the parameters of backwashing in the uniform media filter,reduce water consumption,and solve the problem of filter media loss.Ansys Fluent is applied for multiphase flow simulation for backwashing of uniform media filter material on a three-dimensional scale.In the simulation,the Euler-Eulerian model,Gidaspow model,Schiller-Naumann model,and RNG kεmodel are employed as the multiphase flow model,the drag force between the fluid phase and the solid phase,the drag force between the fluid phases,the turbulence model,respectively.Additionally,particle flow theory is applied to solve the forces between particles.To verify the model simulation,a lab-scale backwashing test is conducted.The results show that the maximum relative error of backwashing head loss h is less than 3%,and the maximum relative error of expansion rate e is less than 10%,indicating a good accuracy of the model.The distribution of particle axial velocity and filter media circulation rate is calculated.To achieve the goal that stable circulations and appropriate expansion rate,the backwashing strength for different particle sizes are optimized.The results show that when the particle size of uniform media is 1.0 mm,1.2 mm,and 1.4 mm,the suitable intensity for water backwashing is(qmf+5)L/(s·m2),and the suitable intensity for simultaneous air and water backwashing is 12.515 L/(s·m2),15.017.5 L/(s·m2),17.520 L/(s·m2),respectively.The average kinetic energy of filter bed surface under simultaneous air and water backwashing is much larger than that under backwashing with single water,which also proves that the effect of simultaneous air and water backwashing is better than the backwashing with water only.

关 键 词：环境工程学 计算流体力学 均质滤料 冲洗强度 滤料环流 

分 类 号：X703[环境科学与工程—环境工程]