Simulation Study On Arrangement Of Aerator In Aeration Tank Based On PBM Model

China's water resources are scarce,the per capita share is only 1/4 of the world average level.and it is one of the 13 countries with poor per capita water resources in the world.Withthe development of society,the total water consumption of our country is stil increasingsigruficantly,but the water area of the city is suffering a lot of pollution,so the sewagetreatment is imminent.Among them,the activated sludge method is an effectivedecontamination method,and the acration tank is the by key equipment of the activated sludgc mcthod.In this papct,the PBM group cquilibrium model coupled with the two Euler multiphase flow model is used in a typical aeration tank.The standard k-? model is used for the numerical simulntion of the turbulence model.The influence of changing the layout of thebottom plate aerator on the parameters in the aeratin tank is analyzed,and the optimal layout of the bottom plate aerator is sclected.The main conclusions are as follows:(1)Model verification one proves that the standard k-? turbulence model and PBM group eqmhbrium model are more suitabk for the simulation of gas-liquid two-phase flow in theaeration tank.Model verification two applies the scheme determined in model verification oneto simulate another experiment.The simulation results are in good agreement with theexpenmenml data.The accuracy and generality of the selected simulation scheme are verified.(2)Through the analysis of the streamline and vector diagram of the characteristic cross sectin.it can be scen that when the bottom plate aerator is evenly arrunged,the two stable circulation fields in ghe tank are more flat and concentrated than other working conditions,so it isconsidered that this arrangement scheme can make the flow field in the tank more stable,andprovied a more stable environment for the gas-liquid mixture.(3)By analyzing the cloud chart of gas volume distribution on different height sections,it canbe scen that when the aerator is evenly arranged on the bottom plate,compared with other working conditions,the gas phase distribution range is wider,the contact area between gas and liquid is larger,and the gas volume fraction on different height sections is higher,which is helpful to improve the oxygen transfer efficiency and make the aerobic microorganism group in the activated sludge in the tank charged Play a role(4)According to the analysis of the vertical velocity nephogram of the liquid phase,the area of the liquid phase non velocity region and the coefficient of the velocity non-uniformity when the aerator is evenly arranged on the bottom plate are smaller than other working conditions.It shows that this scheme is better for the mixing and stirring of sewage in the tank,and can more effectively slow down the deposition of activated sludge.In the same condition,the size of the non flow area of liquid phase in different height section decreases gradually from the bottom to the top of the aeration tank,which shows that the mixing effect of the mixed liquid in the top of the aeration tank is better than that of the bottom(5)Through statistical analysis of the turbulent parameters in each working condition tank,it is found that the turbulent kinetic energy of the bottom plate aerator in uniform arrangement is 1.36-1.6 times of that in other arrangements,and the turbulent energy dissipation rate is 1.85-4.2 times of that in other arrangements.It shows that the turbulence of the mixed liquid in the aeration tank is more intense,and the mixing degree of air and sewage is greater.