城市污水处理厂初沉系统沉淀分离特性模拟

Simulated research for the precipitation and separation features of the primary sedimentation system in the municipal sewage treating plants

利用COMSOL软件模拟和分析了城市污水处理厂辐流式初沉系统三维流态及悬浮颗粒浓度分布状况,并探究颗粒物不同粒径(0.5×10^(-4) m、1×10^(-4) m、2×10^(-4) m、3×10^(-4) m)、挡板不同位置(2.5 m、3.0 m、3.5 m、4.0 m)和挡板不同长度(1 m、2 m、3 m),对初沉系统沉淀效果的影响。研究结果表明:(1)悬浮颗粒粒径大小对初沉系统内流场和浓度场影响较大,平均粒径愈大,相应的沉淀效果愈好;(2)挡板与进水口中心的距离L和挡板长度H对系统的沉淀效果影响明显,当L=2.5 m,H=2 m时,模拟沉淀效果为最优。通过研究掌握初沉系统沉淀和分离特性,并指出可通过优化挡板的位置及长度,构建更为合理的初沉系统运行工况,对进一步指导和优化初沉系统设计革新和建造运行具有一定的实际意义。

In order to build up a more reasonable operating conditions of the primary setting system and improve the operation effect of the sewage treatment plant,this paper intends to provide a numerical simulation model of the radial primary setting system to simulate and analyze the 3-D flow pattern and the suspended matter concentration distribution mode of the radical primary setting system.The afore-mentioned 3-D numerical simulation model of the primary setting system operation is supposed to work with a software named COMSOL by using the RNGκ-εmodel and the mixture model.And,it is used to explore the precipitation effect on the primary setting system under the different particle sizes(say,0.5×10^(-4)m,1×10^(-4) m,2×10^(-4) m,3×10^(-4) m)t the different baffle positions(2.5 m,3.0 m,3.5 m,4.0 m)and different baffle lengths(1 m,2 m,3 m).The results of research show:(1)The increase of the particle size can change the distribution of the suspended matter in the primary setting system,which is different from the hypothesis of an ideal settling tank.And the volume of the suspended particles may have a strong influence on the flow field and the concentration field of the primary setting system.When the average particle size is bigger,the sinking effect of the suspended solids would be getting greater with the precipitation becoming better;And,(2)the addition of baffle is beneficial to the precipitation and separation of the suspended particulate matter.And the distance between the baffle and the inlet center in addition to the length of the baffle may all be related to the precipitation efficiency of the system.And,so,the simulation results show the simulated precipitation would be the best when the baffle position is 2.5 meters with the baffle length being of 2 meters.Therefore,the position and the length of the baffle can be optimized by means of numerical simulation,which is beneficial to the actual operation of the primary setting system.