| At present, circulating cooling water supply system of natural draft counter-flow wet cooling tower in national power plant is usually designed and calculated by design institutions based on annual average meteorological condition of project location, turbine feature and system arrangement. Then the best condenser area, cooling water volume, pump, water in/drain pipe disposition, type and economical disposition of cooling tower can be confirmed. However, due to the influence of one dimension homogeneous intake air's original data condition and large heterogeneous air distribution deviation in practical operation, the cooling efficiency of cooling tower is generally lower than designing number, so that cooling water return temperature standard of turbine back pressure is hard to reach in summer. According to above practical operation condition of counter-flow wet cooling tower, optimization and modification of original design is urgent.On the basis of energy saving optimization technology foundation and current situation of cooling tower in china and abroad, with air dynamics field data in tower, this paper proposes the "water-air two-way optimization distribution" concept of counter-flow Wet Cooling Tower. The concept shall increase cooling efficiency and decrease the circulating cooling water temperature. The specific research contents and results as follows:Firstly, introduction and analysis of cooling tower thermodynamic calculation and mathematical model. Based on CFD calculation software, the author creates a set of simulation program adopting cooling tower thermodynamic feature calculation by user-identified source item; thereby core condition of heat transfer in cooling tower can be known. After simulation study and contrastive analysis, the author puts forward an improved thought which is packing layer height unequal and water spraying heterogeneous.Secondly, through experimental research on performances of two typical nozzles and stuffing in construction, their features and range of application can be mastered. The paper not only discusses how spraying and splashing facilities parameters effect on water distribution capability, but also calculates and analyzes splashing height, coverage, splashing water drops connection between nearby nozzles and distribution after water volume superposition of every nozzle in different distributions. It compares the effect of 3 different distributions on water spraying inhomogeneous coefficient by simulation research on three nozzle group distributions. Based on above, the author presents suggestions of water spraying design optimization and modification to existing spraying and splashing facility. Meanwhile, it learned heating power and resistance features of two common PVC spraying stuffing ("S" wave and double oblique wave) by experiments. After experimental research, local performance optimization and overall efficient distribution can be reached. It also provides foundation for picking various spraying stuffing according to actual engineering need.Thirdly, this paper takes a 300MW thermal power unit cooling tower as an example to strengthen the heat transfer modification with water-air distribution by the "water-air two-way optimization distribution" concept. Through test and analysis of operation data from modified cooling tower, it shows that the actual temperature of modified cooling tower decrease to 8.02?, while in the same condition, the design temperature decrease to 6.21?. The modified cooling tower actual cooling ability is 129.1%, and this technology can obviously improve the cooling ability of cooling tower. |
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