Numerical Simulation Research On Structural Optimization Of Vertical Flow Folded-plate Flocculation Tank

As a significant step in the process of supply water treatment,flocculation is relevant to the effluent quality of the water plant.How to accelerate the flocculation reaction rate and enhance the flocculation effect is a significant subject in the optimization of flocculation facilities.Hydrodynamic flocculation facilities utilize the energy of the water flow as the driving force for hydraulic agitation,which can significantly reduce the operation and maintenance costs of facilities.By researching the hydraulic characteristics of water flow in flocculation reaction facilities and optimizing the structure of the facilities,the hydrodynamic condition can be perfected to facilitate the mixing of flocculants and impurity particles,thus enhancing the flocculation effect.Firstly,the computational fluid dynamics method is applied to solve the flow field in the reciprocating baffled flocculation tank,and the results are compared with the existing flow field researches to ensure the reliability of the numerical simulation method for flocculation facility flow field.Subsequently,the flow field in vertical flow folded-plate flocculation tank is simulated,the flow patterns at various locations are analyzed,the degree of variation in flow velocity and turbulent kinetic energy is observed,and a series of structural optimization measures are taken for the inefficient flocculation areas:(1)By optimizing the wall rectangular structure at the corridor troughs in the first stage flocculation section and at the corridor crests and troughs in the second stage flocculation section,the water flow velocity in shafts of each section is progressively decreasing,and the stagnant water area at troughs is reduced,preventing flocculation particles deposition.The sufficient reaction in the first section is ensured,and the impact of water flow at crests on the wall in the second section is alleviated,facilitating smooth water flow and preventing the particles breakage.(2)By reducing the wall top baffle at the upper bend of the last corridor in the first stage flocculation section,the flow velocity is significantly reduced,resulting in a smoother flow.By reducing the wall top baffles at the upper bends in the second stage flocculation section to protect the particles,and adding a baffle to the wall top at the lower bend in this section,the turbulent kinetic energy of water flow is drastically increased,strengthening the flow disturbance and preventing the particles deposition at the bottom of the tank.(3)By adding the cylindrical spoilers at each folded unit center,the turbulent kinetic energy of water flow in the first stage flocculation section is significantly increased,and the flow disturbance on both sides of each spoiler is strengthened.Due to the phenomenon of flow around cylinders,the water flow in the area behind spoilers slows down and generates micro vortices,which facilitates the formation and growth of flocculation particles.The water flow is diverted to corridor troughs by spoilers,reducing the stagnant water area and preventing the particles deposition.The flow shearing force at the upper bend of the last corridor is reduced,which has a smoothing effect on water flow.The integrated design of these measures can make the overall flow pattern distribution in shafts of each section more reasonable than the original structure.By the comparison of the flow field,the best structural optimization measures are determined: In the first stage flocculation section,the wall rectangular structure at corridor troughs is designed as the corrugated angular structure,the wall top baffle at the upper bend of the last corridor is reduced,and the cylindrical spoilers are added to each folded unit center.In the second stage flocculation section,the wall rectangular structure at crests and troughs of the corridors is designed as the corrugated angular structure,the wall top baffles at the upper bends are reduced,and a baffle is added to the wall top at the lower bend.In the third stage flocculation section,the original arrangement of straight baffles should be maintained.