Computational Fluid Dynamics Simulated The Hydraulic Characteristics Of Air Flotation Tank And Its Application Research

In view of the characteristic of low turbidity and high algae water quality of the South-to-North Water Diversion, the air flotation tank technology has been applied in the treatment process of some water works. But at present, the design of air flotation cell depends on the design manual calculation. In the range of parameters, there is no accurate parameter value method. Study and put forward the Computational Cluid Dynamics (CFD) is used in the simulation to the design of the flotation tank, and on a flat flow type flotation pool, countercurrent flotation tank, mixed flow type air float pool for different parameters of the model for simulation of flow field calculation and post-processing, in gas phase flow diagram, trace gas phase volume distribution nephogram, gas phase volume distribution curve and other visual contrast pool flow in. Model application test analysis also found that the removal effect of air flotation tank and gas flow pattern was positively correlated, so the CFD simulation can be used to guide the design of air flotation tank, and optimize the transformation.The research firstly introduces the software ICEM CFD simulation using CFD 14.5 and Fluent 14.5 operating procedures, including the calculation and model establishment, the establishment and operation of grid software. After establishing a traffic model for 0.5 m3/h, make use of the software to carry on simulation calculation, main research content divided into four aspects:(1) the advection type air float pool simulation optimization and reflux gas dissolved water soluble gas pressure optimization; (2) countercurrent flotation tank simulation optimization and reflux dissolved gas and water soluble pressure force optimization; (3) mixed flow type air float pool simulation optimization and reflux gas dissolved water soluble gas pressure, circumfluence dissolved gas water backwash distribution ratio optimization. Each part of the software simulation research in choose a better tank again after using the software to optimize the calculation, and the establishment of optimized pool type test under optimal conditions. Test switch new flotation tank and the original board Draintrap conditions, verify the flotation tank compared to the inclined plate sedimentation tank and improve the removal rate of the situation.It is found that the optimum design parameters are different from the design pool type, and the optimal flow pattern is different from that of the reflux water solution gas. Advection type air float pool by contact with room to rise velocity for 15 mm/s,2.0 mm/s separation for the speed of the separation chamber, reflux dissolved gas water dissolved gas pressure was 0.45MPa flow best; countercurrent flotation tank by contact chamber increased flow rate of 20 mm/s, separation chamber, the separation rate of 2.5 mm/s, circumfluence dissolved gas water soluble gas pressure is 0.40MPa flow best; mixed flow type air float pool by contact with room to rise velocity for 10 mm/s, separation chamber, the separation rate of 1.5 mm/s, circumfluence dissolved gas water soluble gas pressure is 0.45MPa, circumfluence dissolved gas water ratio is 1:1, the flow pattern of the best. In the optimal case establishing device showed, no matter what kind of return air flotation tank was used, of turbidity, CODMn, TOC, UV remove effect are superior to those of inclined plate sedimentation tank, especially on turbidity removal, a significant advantage. When conditions permit, it is recommended to use the mixed flow air flotation tank to upgrade the technology.Flotation tank of the jade water plant were evaluated in simulation runs, the model simulation, it is found that the precipitation air flotation tank area and flat flow type air float pool optimization results are the same, but because of equipment limitations, and the circumfluence dissolved gas and water soluble gas pressure is difficult to achieve the 0.45MPa. In stable operation of water, Precipitate Flotation sedimentation tank effluent, the air flotation zone effluent, did not transform the advection sedimentation tank effluent sampling inspection found that precipitation flotation pool of turbidity, ammonia nitrogen, algae, chlorophyll a removal effect has significant advantages, but of CODMn removal advantage is not big, it is recommended increase dosage or with other technologies combined to improve the removal effect.