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Research On Improving The Flow Pattern And The Sedimentation Effect Of The Rectangular Secondary Sedimentation Tank Basedon FLUENT Simulation And Fluidization Visualization Experiments

Posted on:2008-01-21Degree:MasterType:Thesis
Country:ChinaCandidate:D ZhengFull Text:PDF
GTID:2121360215989694Subject:Environmental Engineering
Abstract/Summary:PDF Full Text Request
Currently, the flow pattern in the rectangular secondary sedimentation tank of the sewage treatment plant is usually not good. This phenomenon will eventually lead to sedimentation effect and the efficiency of precipitation fell.This paper firstly simulates the flow state of the rectangular secondary sedimentation tank using the CFD simulating software FLUENT, and proves that the flow state of the rectangular secondary sedimentation tank is reasonless through analyzing the flow state in varied conditions, and it also points that the varied commutating measures in the entrance referred in the professional books, which are used to improve the flow state, are not feasible.The paper brings the key device in improving the flow state——lunate guide plate. Through simulating, we find that the flow state can be improved when the lunate guide plate is setting up in the proper place under the inlet baffle plate, and the flow state after improving agrees with the state inferred in ideal sedimentation tank very well.Through designing orthogonal experiments, analyzing the inlet height, the relative position of inlet baffle plate and the inlet, the length of inlet baffle plate, the size of guide plate, and the position of guide plate under the baffle plate, and so on, we can get the most important factor affecting on the flow state in the condition of inlet baffle plate and the guide plate. Simulate and test the FLUENT flow state through the visualization experiments. Intuitively, the flow state in the visualization experiments agrees with the simulating flow state, and the situation, which the sedimentation effect brought by improving the flow state is enhanced, is tested through doing the experiments in the experimental models of sedimentation tank. And the operating effect in the actual sedimentation tank is conjectured out through the similar theory of flow, the removal efficiency can be still increased by 2.22 percents in the condition that the level velocity is three times bigger than the normal velocity in the secondary sedimentation tank, and it indicates that the lunate guide plate will be applied successfully in the actual secondary sedimentation tank.As the lateral subject of the modification works of the wastewater treatment plant in Xiaoshan , the experiments referred in the paper were all completed in the wastewater treatment plant in Xiaoshan.
Keywords/Search Tags:The flow pattern in the rectangular secondary sedimentation tank, FLUENT, Crescent deflector, Fluidization visualization experiment, Removal rate
PDF Full Text Request
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