Research On Operating Conditions Of Aeration Tank Based On Numerical Computation

The efficiency of the aeration tank influences the result of treatment and the cost of power to a large extent due to its important structure of activated sludge sewage treatment system and its highest energy consumption among the whole system. So there is a certain instructive significance to optimize the structure of the tank and improve the management by researching the flow pattern and changing laws.CFD is a simple and convenient method, and it has distinct visualized effects. CFD method can predict the flow field of the tank and analyze the rationality of the designed tank from other angle.This paper analyzed the oxygen transfer mechanism in gas-liquid flow, chose the influence factors which can be simulated in FLUENT, then analyzed the characteristics of the gas-liquid flow in the aeration tank and verified the model.This paper simulated the aeration tank of a sewage treatment factory using standard k-εmodel and Euler model and analyzed the consequences of the spatial distribution of air diffusers, the depth of the tank, the aeration depth, the number of the aeration pipes. It was found that the spatial distribution of air diffusers has the biggest impact on flow field, the depth of the tank has a minimal impact; Rising the position of the pipes could only produce weak turbulence kinetic energy in the under part but not make the air diffuse towards the bottom direction.In addition, analyzing the changing law in horizontal and vertical direction of the flow field is another part of this paper. With the rising of the bubble plumes, the volume fraction of air, turbulence kinetic energy, velocity of the air and water distributes homogeneously. In vertical direction, the changing laws of the main bubble plumes area and juncture zone are different, but the parameters tend to be accordance near the free surface.