Numerical Simulation Of Aeration Performance And Structure Optimization Of Cyclone Aerator

Aeration is an important link in the treatment of industrial wastewater by activated sludge process.At present,the mainstream aeration equipment includes microporous aerator,cyclone aerator and jet aerator.Cyclone aerator has many advantages,such as strong mixing ability,long service life and stable operation in the later stage,which has a strong competitive advantage in the development of aeration equipment in the future.However,there are some problems in the cyclone aerator at present,mainly due to the large size and uneven size of the cut bubbles,which leads to the low oxygen utilization rate.In this study,CFD-PBM coupling model was used to describe the coalescence and fragmentation of bubbles in the aeration tank under the action of swirling aerator.In the process of the air bubble breakage,the part of the cutter plays a key role.This study mainly analyzes the change of aeration performance of the cyclone aerator by changing the shape of the cutting teeth,the number of cutting teeth and the number of cutting teeth in each layer.Firstly,under the same conditions of other parameters,the parameters of single factor are gradually changed,and the influence of this factor on the bubble crushing rate and the pressure difference of inlet and outlet of swirl aerator is analyzed,and then the function relationship between them is fitted.Secondly,the influence of multiple factors on the bubble crushing rate and the pressure difference of the aerator inlet and outlet is analyzed.In order to reduce the number of tests,the test table is established by uniform test method,and the function expression between them is fitted by using the DPS data processing software by stepwise regression analysis.Thirdly,the fitting function is optimized by using the multi-objective genetic algorithm(NSGA-II),and Pareto optimal solution set is calculated.According to the actual requirements,a set of optimal parameter collocation is selected from the optimal solution set.Finally,the results of the optimization model and the original model are compared and analyzed to verify the accuracy and feasibility of the optimization model.Under the influence of a single factor,it is found that the cutting performance of triangular prism cutting teeth is better for bubble cutting,and the functional relationship between the number of cutting teeth in each layer and the number of cutting teeth layers and bubble breaking rate and pressure difference is fitted in turn.After NSGA-Ⅱ algorithm is used to solve the problem,it is found that there is a game relationship between the bubble breaking rate and the pressure difference.Under the condition of meeting the actual pressure difference,the bubble breaking rate is the highest when triangular prism,12 cutting teeth in each layer and a total of 9 layers are selected.After comparing the optimization model before and after,it is found that the bubble breaking rate is increased by 32.7%,which verifies the accuracy and scientificity of the optimization model.