The Study On Optimization Of Sediment Equipment With The New Enhanced Flocculation Device-based On CFD

With the rapid development of China’s economy,the issue of drinking water security plays a decisive role,especially in the vast rural areas because of the lag of wate supply facilities.There is still some rural residents can not get safe drinking water.In face of the stern situation of the drinking water security of the rural area of China,the integrated water purification devices has strong realistic significance because of it’s characteristics such as convenient operation,widely used in extensive water conditions and can be mass production.The study based on the sediment equipment with the new enhanced flocculation device which is designed by research group leaded by Professor Jiang Shaojie.The selection of design parameters of the sediment equipment were depend on experience.To solve the problem of design parameters of key positions,which influences the treatment efficiency of the sediment equipment,using CFD software—FLUENT to optimizing equipment’s design.After analysis and comparison,establish the model based on RNG k-ε turbulence model,SIMPLE algorithm,the second upwind scheme,discrete phase model based on lagrange method.Establishing models of each important part of the sediment equipment.The models is divided into several smaller area.The results show that all models can generate meshes with reasonable quality.The boundary conditions for the study as follows: velocity-inlet,outflow,wall function,rigid-lid hypothesis.The design flow is 240 m3/d.Density of water is 998.3 kg/m3.Viscosity coefficient of water is 1.005×10-3.Density of floc particle is 1050 kg/m3.Diameter of floc particle which is treat as homogeneous sphere is 0.5 mm.When the submerged depth of upper water-crossing section of external flocculation zone is 75 mm,can balance the particle distribution uniformity and control of velocity.When the height of lower water-crossing section of external flocculation zone is 200 mm.Floc particles are less likely be broken by flow shear stress.At the same time,flocs distribution uniformity on the export section.There is a floc particles float zone which is contribution to enhance flocculation in both cases.When the divergence angle of conical diffuser of central flocculation zone is 60°,can control vortex in a small zone which do not affect particle distribution uniformity on the export section,guarantee reasonable floc particle removal rate.At the same time,the conical diffuser part can coordinate with other parts of the equipment,and reduce the equipment height.When the diameter of passage of water is 300 mm,can achieve minimum disturbance of sludge zone.Two vortex areas are formed along the Y direction.At the same time,installation of spoiler and equipment design requirement can be satisfied.If move the passage of water up the water would flow along the wall of the cone bottom to the sludge zone and stir up bottom mud.When the hole diameter of collection gallery which is orifice water collection system in nature is 7 mm,water distribution uniformity on the hole section.The disturbance of the process on the inclined plate,energy consumption and unit water cost can be controlled.When the hole diameter is 7 mm,the collection gallery satisfy the formula of homogeneity of high resistance water distribution system.When the angle of deflector is 45°,horizontal distance is 70 mm,submerged depth is 30 mm,can effectively reduce vortex area,so that the floc particles which has deposit to the top zone of inclined plate would not be roll up.The average velocity is too small to destroy flocs.Because of the deflector,the distal flocs distribution percentage increase slightly.It is helpful to improve the efficiency of spiral inclined plate.The simulation of external flocculation zone show the reliability of local model and design of flocculation plates.The analysis in different flow show the ability to resist flow fluctuation.The simulation of spiral inclined plate show that the design objective have been achieved.The analysis in different flow and remove of high-density particles show the ability to separate mud with water.