Research On The Optimization Of The Aeration Tank With Suspended Packing Based On CFD

It takes the first-class biological contact oxidation tank of reclaimed water station of Hebei University of Arcgitecture as the research object.In terms of the type of packing in the tank,for it is suspended elastic three-dimensional packing,it is distinguished as an aeration tank with hanging packing.The CFD commercial software package ANSYS Fluent 15.0 was applied to carry out three-dimensional numerical simulation of the aeration tank with suspended packing in the reclaimed water station.With the aeration tank being scaled down by 0.1 to build the test device to ensure the accuracy and reliability of the simulation results,the finding is that the simulation results correspond closely to that of the experiment.This simulation selects the Euler model in which the turbulence model uses the standard k-? model to close the Reynolds time-average equation.The interaction force ignores the lift and the virtual mass force.Only the resistance considered,and with the use of Schiller and Naumann for the drag function,and Coupled for the pressure velocity coupling,the algorithm sets the aqueous phase to the main phase,the gas phase to the secondary phase,and the bubble diameter to 3 mm.The simulation process is in a non-steady state.When the discrete equation is used,except for the volume fraction,the second-order upwind style is selected,and the under-relaxation factors are in the default mode.The aeration rates were respectively set to be 0.17m/s,0.67m/s,1.17m/s,1.67m/s,2.17m/s,2.67m/s,and it has the optimal effect when the gas velocity was 1.17m/s.Observing the gas phase flow vector diagram of the gas-liquid two-phase flow in the aeration tank,the liquid phase flow vector diagram and the gas content distribution in the pool,it is found that the bubble has a certain period of oscillation when the aeration speed is 1.17m/s,and the bubble is increased.The residence time in the water,and the turbulence between the gas and liquid phases is severe,and the time required for gas phase saturation is short,which is favorable for the oxygen mass transfer.The packing heights were set to 0.3m,0.7m and 1.1m respectively.After the analysis of the gas content and turbulent kinetic energy of the same aeration tanks at different heights and the same height in the different aeration tanks,the result is that the optimum packing height was 0.7m.When the packing height is 0.7m,both the gas content and the turbulent energy are superior to other conditions.By discussing the distribution of the flow field in the pool at different aeration speeds and packing heights and optimizing the internal structure with the suspended-filler aeration tank,it is aimed at,without affecting the oxygen delivery efficiency and wasting the energy,finding the appropriate aeration speed and optimum packing height to make the gas-liquid two phases in the tank fully mixed,improve the treatment efficiency of the aeration tank,and achieve economic and energy saving effects.