Numerical Simulation Of Hydraulic Characteristics Of Solid-liquid Two-phase Flow In Inclined Plate Sedimentation Tank

The plated sedimentation tank is widely used in water treatment works in our country,has high processing efficiency,sludge settling time is short,and the advantages of cover an area of an area small,however,this type of settling tank in the process of actual operation pool flow field and concentration field in the body change rule is extremely complex,in the practical engineering effect on some of its structural parameters and operational parameters analysis system comprehensive enough,this study based on the theory of computational fluid dynamics numerical simulation on the hydraulic characteristics of inclined plate settling basin,treatment of precipitation process has a certain guiding significance to the adjustment and optimization.The research results are as follows:(1)With the Fluent software,the Mixture multiphase flow model and the RNG k-Mixture turbulence model are adopted to numerically simulate the mechanical characteristics of solid-liquid two-phase flow in the inclined plate sedimentation tank.The mathematical model was established and the experimental data of concentration field in the improved inclined plate sedimentation tank were compared with the simulation results to verify the model.The results show that the simulation results are in good agreement with the experimental data,and the error is within the acceptable range,which proves the applicability of the selected mathematical model.(2)Influence of body structure of inclined plate sedimentation tank(inclined plate spacing,inclination Angle and height of distribution area)on hydraulic characteristics of sedimentation tank.The research shows that when the distance between slant plates decreases from 12cm to 5cm,the concentration of suspended substances in the outlet of the sedimentation tank decreases and the removal efficiency increases by 3.6%.The operation efficiency of the sedimentation tank is the highest when the distance between slant plates is 5cm.When the inclination Angle of the inclined plate was reduced from 65°to 45°,the removal rate of suspended matter in the sedimentation tank was improved by 4.6%.When the inclination Angle was 450°and 60°,the removal rate was better than other working conditions,85.4%and 84%,respectively.When the height of water distribution area increases from 1.5m to 1.8m,the operating efficiency of sedimentation tank changes little,within the range of 84%?86%.When the height of the distribution area increases from 1.8m to 2.1m,the operating efficiency of the sedimentation basin changes greatly.On the whole,the removal rate of the sedimentation basin increases by 6.6%when the height of the distribution area in this simulation increases from 1.5m to 2.5m.Increasing the height of water distribution area is beneficial to improve the effluent quality.(3)Influence of operation parameters(inlet velocity,sludge concentration and sludge particle density)of inclined plate sedimentation tank on hydraulic characteristics of sedimentation tank.The research shows that the removal rate of sedimentation tank decreases by 6.8%with the increase of inlet flow rate from 0.06m/s to 0.20m/s.When the concentration of imported sludge increases from 300mg/L to 600mg/L,the removal rate of sedimentation tank decreases accordingly,decreasing by 5.4%.The increase of the concentration of imported sludge is not conducive to the stable operation of sedimentation tank.With the increase of inlet sludge particle density,the removal rate of sedimentation tank also increases.When the particle density increased from 1000kg/m3 to 1500kg/m3,the removal rate of mum sedimentation tank changed greatly and increased by 7.8%.Proper increase of sludge particle density is beneficial to improve the operation efficiency of sedimentation tank.