Three-dimensional Numerical Simulation Of Tube Settler

In recent years, along with the expansion and reconstruction of municipal water plants, its construction costs also increased accordingly, so research and explore optimization method of urban water supply treatment technology and energy-saving way as well as fundamentally change the current situation of municipal water supply plants high investment cost is particularly important. Settling basin as a great deal of important link in water treatment, the stand or fall of between precipitation process and water treatment technology has a direct correlation. But the design of settling basin is mostly based on standard and experience to select design parameters, so there is no guarantee that settling basin running under optimum condition. At present, the studies of tube settler are mainly concentrated in the aspect of theoretical analysis,numerical simulation was studied rarely. So this thesis chooses the three-dimensional numerical simulation method to study tube settler.The purpose of this study is to compare the efficiency of precipitations under different working conditions based on the numerical simulation of tube settler and get the optimal design parameters of tube settler as well as come up with more economic and reasonable optimization scheme of settling basin. The study background of this thesis is actual operational waterwork which is situated in Antarctic Township of Ningguo City in Anhui Province, adopting simulation software to simulate the velocity field and suspended solids concentration field of tube settler under different inclined-tube diameters and different inlet velocities respectively, and calculate out the suspended solids removal rate under different working conditions.The results are as follows:(1) The diameter of inclined tube only be guaranteed within a certain range can make tube settler has a ideal precipitation efficiency; when the diameter is equal to 25 mm to 40 mm, the precipitation effects of tube settler are similar and ideal; but when the diameter is equal to 45 mm, the efficiency of precipitation drops substantially, considering the pipe diameter is too small easy to jam, and increase the operation cost, but the precipitation efficiency value is not high, so this study suggests that using 35 mm and 40 mm as the optimal pipe diameter design value;(2) The bigger the density of suspended particles, the bigger the particle settling velocity, the more conducive to the settlement of particles, and the precipitation effect of tube settler isbetter;(3) The change of the orifice position on perforated wall can affect the precipitation efficiency of tube settler, whether the orifices are too close to sludge area or inclined district will reduce the removal rate of suspended solids.From the result of simul ating,it is gained that the best orifice set positions are away from sludge area more than0.5m,at the same time, apart from inclined district no less than 0.4m.(4)The perforated w all uses circular orifice better than rectangular orifice in flow field and precipitation efficiency.The conclusion of this study has a certain guiding significance for the design of tube settler. By optimizing the tube diameter and the inlet velocity can improve the deposition efficiency of tube settler as well as make the tube settler to become more efficient,economic and stronger adaptability.