Application And Cfd Simulation Of Composite Aerator Based On Rotary Float Valve In Aeration Tank

Microporous aerators are widely used on the market.Microporous aerators produce smaller bubbles than other aerators,thus have higher oxygen utilization.The rubber on the surface of the microporous aerators will gradually aging as the working time increases,which reduces the oxygenation effect,and also have the disadvantage of clogging.In the actual sewage treatment process,the gas content rate is low between the aerators and in the area directly above the aerator due to the installation arrangement and its own characteristics,and there is a mass transfer dead zone.In the study of the hydrodynamic performance of the rotary float valve,it is found that when the gas passes through the valve plate,it will spirally rotate from the gap between the rotary float valve and the tray,which has a strong guiding effect on the surrounding liquid layer,around the rotary float valve.There is a rotating flow field,which makes the gas-liquid contact more uniform.Based on the fact that the gas can form a rotating flow field around the valve cover after the rotary valve is rotated,and there is a mass transfer dead zone in the aeration service area directly above the aeration head between the microporous aerator,a float valve-bubble stone composite aerator was proposed and its aeration and oxygenation performance was studied.The float valve-bubble stone composite aerator consists of a float valve and six bubble stones uniformly arranged around it.In an organic glass aeration tank with an inner diameter of 800×600×910 mm,air and tap water are used as experimental systems.The comprehensive performance of the rotating(and F1)float valve-bubble stone composite aerator was investigated separately.In order to better explain the cause of the formation of the rotating flow field and the agitation of the rotating flow field from the microscopic point of view,this subject also uses CFD to simulate the flow field distribution of the gas after passing through the valve.The experimental results show that the introduction of the float valve improves the aeration effect of the bubble stone.Rotating float valve-bubble stone composite aerator has better oxygenation uniformity index than F1 type float valve-bubblestone composite aerator;Rotating float valve-bubble stone composite aerator and F1 float valve-bubble stone composite aerator have higher oxygen mass transfer coefficient and oxygen mass transfer rate than bubble stone aerator,and have lower oxygen mass transfer efficiency and aeration efficiency than bubble stone aerator.The CFD simulation results show that the existence of the rotary float valve not only increases the residence time of the bubbles in the liquid layer,but also causes the bubbles to diffuse around the aeration tank,which makes the bubble distribution more uniform,reduces the mass transfer dead zone.It can improve the disadvantage of relatively low gas content between microporous aerators.The simulation results are consistent with the results of aeration and oxygenation experiments.Providing a new idea for the improvement of aeration equipment.