Numerical Simulation Of Liquid-Solid Two Phase Flow In Modified Inclined Plate Sedimentation Tank And Experimental Study Of Separation Properties

As common liquid-solid separation equipment, sedimentation tank (ST) plays an important role in the water treatment. With the increasingly demanding of the state to the sedimentation efficiency, the improvement and optimization of the sedimentation tank is necessary and imperative. There is little consideration to the tank structure in the previous work, which is only based on practical experience and without any numerical simulation and experimental analysis, then, it has a restrained guiding function to the practical engineering.A modified inclined plate sedimentation tank is studied in this paper, which is formed by adding an inclined plate to the vertical flow sedimentation tank and greatly makes up for the shortages of the traditional vertical flow sedimentation tank or inclined plate sedimentation tank. FLUENT software simulates three structure conditions in this modified sedimentation tank. Numerical simulation of the unsteady liquid-solid flow is chose because of the flow field and concentration field changing with time. Eulerian multiply phase flow model and RNG k-εturbulent flow model is used in this work. The optimum structure dimensions are determined by the simulation results.The sedimentation efficiencies are varied under different operating conditions in real work. By studying the simulation results of different suspended particle densities, particle diameters, suspended particle concentrations in the inlet and inlet flow velocities and by analyzing the influence of these factors to the flow fields, concentration fields and removal rates, some important conclusions are obtained. The sedimentation efficiency increases as the increment of the particle density and particle diameter in the suspension and decreases as the increment of the volume fraction of particle in the inlet suspension. The sedimentation efficiency also increases if the inlet flow velocity is enhanced. The optimal working condition of the modified inclined plate sedimentation tank can be determined by these results.In order to verify the correctness of the simulation, a test bench is also designed and built with the numerical simulation optimal structure parameter. The removal rate of ash-flushing wastewater in the modified inclined plate sedimentation tank is studied by experiments in this work. The removal rates of different particle concentrations and flow velocities in the inlet are tested, which have a good consistency to the simulation results. Besides, the removal rates of the vertical flow sedimentation tank and modified inclined plate sedimentation tank are also compared by experiments. The particle removal efficiency is greatly enhanced by installing the inclined plate in the tank.