The Study Of Circular Grid Plate Hole Effect On Flocculation Hydraulic Conditions Of Grid Flocculation Tanks

So far, the flocculation process still plays an irreplaceable role in water treatment. This technology makes suspended particulate matter of raw water gathered or develop to bigger floc, accelerating the coagulation of particle, and finally achieve the solid-liquid separation. In this case, a study of flocculation process in water treatment is very necessary.Based on the method of numerical simulation, taking vortex velocity gradient G’.turbulent kinetic energy k,turbulent dissipation rate ε and head loss H as an evaluation index for flocculation, we made an research on the comparison between thetraditional square holes and improvedcircular holes in grid flocculation tank, and obtained the hydraulic characteristics of internal flow fields in the front, middle and end section of two kinds of grid flocculation tanks. Aiming to improve flocculation effect, a comparatively best hydraulics condition for grid flocculation tank is discussed.Taking an actual Waterworks in Anhui province single cell processing ability of 10000 m3/d 24 shaft lattice grid flocculation tank as the calculation model, the results are as follows:1、In a same flow velocity,circular holes in grid flocculation tank flocculation effect is obviously superior to the square shape; under the same condition of flocculation effect, circular hole can increase energy consumption and reduce grid flocculation tank volume.2、According to The grid flocculation tank design standards, taking 80 mm from front, and 100 mm from middle of square grid hole side as reference, the circular eyelet gridding flocculator for simulation of circular holes in the preceding optimal diameter is up to 86.5 mm, and 107 mm in the middle of the optimal diameter. Using a set of circular hole diameter on the flocculation is obviously a better choice.3、According to The grid flocculation tank design standards, grid plate spacing should take 600-700 mm as reference, the optimal circular hole diameter of the grid plate is simulated, optimal grid plate spacing is 600 mm.Taking single cell processing ability of 5000 m3/d and 20000 m3/d 6 shaft lattice grid flocculation tank as the calculation model, further simulation of circular hole optimal diameter and circular hole plate grid optimal spacing, the research results are as follows:1、The 5000 m3/d and 20000 m3/d circular eyelet gridding flocculator for simulation of circular holes in the preceding optimal diameter is up to 86.5 mm,107 mm in the middle,which is consistent with the conclusion of 10000 m3/d circular eyelet gridding flocculator,verifying that this optimal diameter could be applied to different types of grid flocculation tank.2、The optimal circular hole diameter of the grid plate is simulated,5000 m3/d and 20000 m3/d circular eyelet gridding flocculator’s optimal grid plate spacing is 600 mm, which is consistent with the conclusion of 10000 m3/d circular eyelet gridding flocculator,verifying that this optimal grid plate spacing could be applied to different types of grid flocculation tank.The results obtained in this paper are of guiding significance to the optimization of the grid flocculation tank in a certain degree.