Research On The Optimal Design Of Horizontal Flow Sedimentation Tank

As a traditional widely used structure in the field of water purification process, the advantages of horizontal flow sedimentation tank are as follows:the setting efficiency is favorable and the structure can resist the loading fluctuation, however, its floor space is relatively large. The disadvantage limits its application. How to realize the goal of slashing costs on the basis of ensuring its setting efficiency is very necessary.This dissertation focused on the second waterworks with the method of numerical simulation. The structured grids were generated in ANSYS ICEM CFD, then imported mesh files into the FLUENT software, the velocity field and concentration field in setting tanks could be obtained by using the Mixture model, the standard k-epsilon model and the PISO iterative solution. As a result, this paper got the simulation result of the flow distribution including the streamline, the velocity, the volume fraction of SS and the turbulent kinetic energy and so on.The working condition simulations mainly included two parts, the analog variables consist of SS properties and configuration dimensions of horizontal flow sedimentation tank. The simulation datas showed that the setting efficiencies obviously changed which caused by particle diameter and density. The setting efficiency increases with the enlargement of SS average diameter and density. The effects about setting efficiency brought by the variation of the length and width were slight, however, the situation brought by the variation of the water depth was very significant. The setting efficiency decreases with the enlargement of the water depth. According to the results, the author proposes that water depth of horizontal flow sedimentation tank ranged appropriate from 3m to 4m.According to the numerical simulation results and costs datas of horizontal flow sedimentation tanks, The curves about setting efficiencies and costs of horizontal flow sedimentation tanks could be fitted out by using the MATLAB software. An optimal solution could be obtained by building a reasonable optimization design model and the goal of slashing costs could be realized on the basis of ensuring its setting efficiency. The reserch provided several guidance for construction and operation in engineering.