| Supercritical indirect air-cooled unit will be widely used in areas with abundant coal and deficient water, along with continuous development of air cooling technology. A mathematical and physical model which can reflect air flow character and heat transfer performance was built in this study based on not only the choice of flow and heat transfer correlations that correspond to different structure types of finned tube bundles for indirect air cooling radiators, but also the consideration of air cooling tower flow resistance on every component and calculation formulas of suction force for different radiator wall temperature.A series of analysis taken for a given structure of air-cooed tower were as follows: the inlet air pressure distribution of radiator unit changed with different ambient wind speeds because of air flow passing around air-cooled tower, the inlet air temperature of radiator unit changed with different ambient temperatures because of radiator unit inlet air temperature changing, the flow rate and temperature of cooling water changed with different unit load, which all lead to changes of heat dissipation ability for air-cooled tower, thereby impact back-pressure of condenser. A calculation program compiled by Matlab established a mathematical model for variable condition property of electric power plant indirect air-cooled system and gave a calculation flow diagram, which lay the theoretical foundation for analysis of indirect air-cooled unit characteristics. Taken a typical2X660MW indirect air-cooled unit as an example, the changing rule of the indirect air-cooled unit back-pressure with ambient wind speed, ambient temperature, exhaust steam flow rate, circulating water flow rate were analyzed and a reference for the operation and design of power plant air-cooled system were provided as well. |
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