Numerical Simulation Study Of Radial Flow Sedimentation Tank That Inlet Of Water Is At Central And Outlet Is At Periphery

The optimization of sewage treatment structures has become one of the current research contents since the problem of water pollution has become more and more serious with the rapid development of society.The radial flow sedimentation tank with central inlet has less disturbance to the water body and strong impact resistance,which is widely used in sewage treatment plants.It is necessary to conduct in-depth research on the sedimentation tank to obtain the optimal parameter value due to the fact that some parameters of the sedimentation tank are not clearly defined in the current design manual and specifications and only the empirical value can not optimize the hydraulic conditions of the sedimentation tank during the actual operation.The mid-peripheral radial flow sedimentation tank was simulated based on the numerical simulation method,the internal flow field map of the sedimentation tank was analyzed and the suspended solids removal rate was used as the evaluation index.The influence of parameters such as the depth of the baffle,the distance between the baffle to the water hole,the distance between the sump to the side wall,and the width of the sump to the sedimentation efficiency were studied.The results were showed:(1)The optimal ratio of the baffle depth to the center height of the tank is 0.46 when the scale of the sedimentaition tank is 5000m~3/d,and the optimal ratio of the baffle depth to the center height of the tank is 0.5 when the scale of the sedimentaition tank is20000m~3/d,and the optimal ratio of the baffle depth to the center height of the tank is0.56 when the scale of the sedimentaition tank is 40000m~3/d,so the optimal ratio of the baffle depth to the center height of the tank is 0.4~0.6.(2)The optimal ratio of the distance between the baffle and the water hole to the radius of the tank is 0.071 when the scale of the sedimentaition tank is 5000m~3/d,and the optimal ratio of the distance between the baffle and the water hole to the the radius of the tank is 0.074 when the scale of the sedimentaition tank is 20000m~3/d,and the optimal ratio of the distance between the baffle and the water hole to the the radius of the tank is0.079 when the scale of the sedimentaition tank is 40000m~3/d,so the optimum ratio of the distance between the baffle and the water hole to the radius of the tank is 0.07~0.08.(3)The optimal ratio of the distance between the sump to the side wall to the radius of the tank is 0.24 when the scale of the sedimentaition tank is 5000m~3/d,the optimal ratio of the distance between the sump to the side wall to the radius of the tank is 0.22 when the scale of the sedimentaition tank is 20000m~3/d,the optimal ratio of the distance between the sump to the side wall to the radius of the tank is 0.25 when the scale of the sedimentaition tank is 40000m~3/d,so the optimal ratio of the distance between the sump to the side wall to the radius of the tank is 0.2~0.3.(4)The optimal ratio of the sump width to the radius of the tank is 0.024 when the scale of the sedimentaition tank is 5000m~3/d,the optimal ratio of the sump width to the radius of the tank is 0.022 when the scale of the sedimentaition tank is 20000m~3/d,the optimal ratio of the sump width to the radius of the tank is 0.029 when the scale of the sedimentaition tank is 40000m~3/d,so the optimal ratio of the sump width to the radius of the tank is 0.02~0.03.The simulation results have certain reference significance for the actual engineering design of the radial flow sedimentation tank.