Study On Sedimentation Effect Of Inclined Plate Sedimentation Tank Based On CFD

Due to the structural constraints of the inclined plate sedimentation tank,it is extremely difficult to understand the movement trajectory of fluid and particles in the tank,and studying the hydraulic characteristics and influencing factors of the tank has always been a key point in water treatment processes.In this thesis,Computational fluid dynamics(CFD)technology is combined with practical engineering to analyze the flow pattern and operating efficiency of sedimentation tank under different variables,provide internal parameters of the tank,and try to adjust the shape of inclined plate.This thesis studies the inclined plate sedimentation tank of the water station.Based on the small server of the research group and the Beijing Cloud Supercomputing Center,and based on the CFD numerical calculation,the Euler Lagrange method is used,and the one-way coupled discrete phase model(DPM)is used for numerical calculation.To study the particle deposition characteristics and flow pattern changes in inclined plate sedimentation tanks under different operating conditions,three operating conditions were set for inorganic particle analysis,namely particle density and particle size,and different shapes of inclined plates.The density was designed to be 800kg/m~3,1000kg/m~3 And 1300kg/m~3 Three types were designed,with particle sizes of 60 um,80um,and 100 um.A V-shaped inclined plate was attempted to be designed for the shape of the inclined plate,and the research conclusions are as follows:(1)The particle size is directly proportional to the flow velocity and turbulence level in the water distribution area.According to the analysis of the flow pattern in the tank,the strength of the vortex at the inlet of the sedimentation tank varies with the particle size.When the particle size reaches 100 um,the large vortex affects the flow pattern below the inclined plate,and the water flow at the outlet is uniform.At the same time,the particle size increases,which increases the flow velocity at the water distribution area and sludge hopper.The velocity distribution and numerical value in the clean water area do not change much,and both are uniform and slow outflow.Analyzing the particle motion trajectory,it was found that when the water flow speed is low,most particles rely on their own density to settle to the bottom of the sludge hopper.However,when the particle size is 100 um,the particle descent speed is slow,approaching a suspended state.The three types of particle size pressure areas are all concentrated in the water distribution area.The larger the particle size,the more obvious the pressure stratification in the water distribution area.The pressure value in the inclined plate area is inversely proportional to the particle size,and the particle removal rate in the sedimentation tank is directly proportional to the particle size.(2)The closer the particle density is to the water flow density,the more stable the flow pattern of the pool is.When the particle density increases from 800kg/m~3 Increase to 1000kg/m ~3.When the density increases from 1000kg/m,the range of vortex waves decreases and they are all within the water distribution area~3 Increase to 1300kg/m~3.When the density is close to the flow density,the influence of Density contrast is small.At this time,the flow pattern is more stable,and reducing or increasing the density will increase the turbulent dissipation rate of the sedimentation tank to varying degrees,making the vortex diffuse.When the density is lower than the water flow density,the change in density has little effect on the internal values of the pool.The maximum pressure of the three conditions appears in the middle section of the water distribution area,while a negative pressure zone appears at the water distribution pipe.The flow pattern at the inlet is uniform,and the inclined plate plays a good role in drainage.When the density is greater than the water flow,the particle density is directly proportional to the removal effect.(3)The improved inclined plate has improved the operational efficiency of the sedimentation tank.The angle of the upper half of the inclined plate is adjusted to45°.At this time,the vortex range in the water distribution area decreases,but the vortex intensity increases.At this time,energy dissipation is faster,and the water flow speed in the water distribution area and sludge area decreases.At this time,the flow state is more stable,which is conducive to preventing sludge from floating again and improving operating efficiency.After calculation,the removal rate of V-shaped inclined plate particles is 1.74 percentage points higher than that of ordinary inclined plates.