| Large-scale indirect air-cooling unit has a good application prospect in North China which is rich in coal and short of water, and plays an important role in energy conservation and emissions reduction of electric power industry in our country. The operating characteristics of indirect air-cooling system studied in different aspects in this thesis, are the important foundations for safe and economic operation of the unit, and some guiding suggestions for optimization are proposed,. The main contents of the thesis are showed as follows:Indirect air-cooling system has been separated into three parts, that is, circulating cooling water, air-cooling tower and condenser. With theoretical calculation and numerical Simulation, the distribution of circulating cooling water in the system and the characteristics of flow and heat transfer about air-cooling tower under different environmental conditions are obtained. Combining the condenser, the analysis is employed on variation regularity of the indirect air-cooling system changing with the environmental temperature, wind velocity and unit load.The models of air-cooling tower and condenser for dynamic response are separately established, and characteristics of the two models under different disturbances are obtained. By coupling these two dynamic models together, the responses of indirect air-cooling system to the disturbances of load, environment and flow rate of circulating cooling water are obtained respectively.Based on the operating characteristics of air-cooling tower and condenser under different conditions, a model of indirect air-cooling system is established using least squares support vector machines. With this model, operating mode of indirect air-cooling system under different conditions is optimized, and the software for system optimization is developed to guide the actual operation. |
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