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Study on the Characteristics and Simulation of the Hydrocyclone Reparation Process for Initial Rainw

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Tutor: HuangXianHuai
School: Construction Industry Institute
Course: Municipal Engineering
Keywords: initial rainwater,hydrocyclone separation,CFD,model simulation
CLC: X522
Type: Master's thesis
Year:  2011
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Abstract:
With the social development in recent years, the point source pollution has been controlled by steps. Now the non-point pollution to the quality of water are becoming the major reason of the pollution in water among cities. The meaning of non-point pollution is the pollution which caused by dissolved or solid contamination of earth surface or atmosphere, when it¡¯s raining. It happens at unfixed location or time, but it with regionality. The pollution of early-stage rainfall is the main component of city non-point pollution. In the high urbanization place with earth surface polluted highly, although useing the distributary drainage system, the containing water is also polluted seriously by the direct emissions of the early-stage rainfall. There are some advantages of the Hydrocyclone separator, such as a compact structure, small size, light weight, easy to design and installation, low maintenance cost, easy adjustment and control, etc. So the designed of Hydrocyclone separator for processing rainwater was used in this paper. In the study, the simulation experiments were done for early-stage rainfall and the water distribution of different particle size of Kaolin or different water concentrations in the lab. The removal effect of hydrocyclone worked on SS under the different structural parameters were observed. The experimental results showed that:(1) There is a good effect on removing COD and SS of rainwater samples which come from Qing¢òChong in the separation of hydrocyclone. With the increasing of inlet pressure, the treatment effect was an increasing trend in general. With the influent concentration, the removal rate was the first increase and then decrease with the inlet pressure 0.02Mpa. The removal rate of SS was up to 80.9% and the removal rate of COD was 64.7%. The removal rate of campus was slightly lower ,which values of those two rate was 64.3% and 56.8%.(2) Additional, there is a good removal on kaolin with fixed size or different size in water of the hydrocyclone separation. The removal rate of the two kinds water samples of kaolin were equivalent to about 80% .(3) Hydrocyclone showed a high performance for various water samples; although at different parameters granular particles moved randomly in the cyclone separator and granular removal ratio was unstable, experiments manifested a good efficiency on granular removal results when overflow tube was inserted up to 6 centimeters with cone angle of 15 and column a high of 15 centimeters. Therefore the results could be considered as optimal hydrocyclone structure parameters under the experimental conditions. After obtained the optimal structure parameters of hydrocyclone separator, using the Gambit software to dispose it, and using FLUENT software to stimulate the inside of field flow, and then the diagrams of distribution, velocity vectors and velocity for the optimal structure parameters were obtained. Basis on these, verification analyse the separation mechanism of cyclone. The results of simulation demonstrated that: the static pressure around near the inlet of Hydrocyclone was comparatively high and decreased gradually in radial direction and outwardly while pressure was low around center axis;Inlet pressure varied considerably and dynamic pressure dropped gradually with decreasing radius. However,axial dynamic pressure gradient changed sharply. Tangential velocity increased and then decreased on the whole and shared consistency which verified the theory that direction of rotation revolves accordingly; The existence of zero speed envelope was proved by the simulation of the axial velocity. Therefore,we can consider that the feasibility of using CFD method of FLUENT software to simulate the internal flow field of cyclone separator. It also lay the foundation for the further research on the characteristics of cyclone flow field and optimization design of hydrocyclone.
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