干湿联合冷却系统的性能分析

Performance analysis of dry and wet combined cooling system

干湿联合冷却系统能够有效缓解空冷机组的夏季高背压、限负荷等问题,提升机组运行的可靠性和经济性。以某电厂600MW机组为例,建立干湿联合冷却系统的数学模型,确定其运行工况点,分析机组排汽量、冷却水流量、环境温度及风机转速等对机组背压和空冷、水冷系统蒸汽分配量的影响。结果表明,在设计工况下,干湿联合冷却系统的排汽压力比直接空冷系统降低了2.6k Pa。当机组排汽量从70%提高到100%时,背压提高了2.7k Pa,而水冷系统的蒸汽分配量从10.7%上升到13.9%;当水冷系统的冷却水量从4000t/h提高到12000t/h时,背压下降了0.9k Pa,而水冷系统的蒸汽分配量从9%上升到13.9%;当环境温度上升到35℃时,干湿联合冷却系统背压比纯空冷系统下降了10.7k Pa;当空冷系统的风机转速从60%上升到100%时,背压下降了6.3k Pa,而水冷系统的蒸汽分配量从22.9%下降到13.9%。

The combined dry and wet cooling system can effectively alleviate the problems of high backpressure and load limitation of air-cooled units in summer, and improve the reliability and economy of unit operation. Taking the 600 MW unit of a power plant as an example, the mathematical model of dry and wet combined cooling system is set up, and its operating point is determined. The influence of unit exhaust volume, cooling water flow, ambient temperature and fan speed on the steam distribution of the backpressure and air cooling and water cooling system of the unit is analyzed. The results show that under the design conditions, the exhaust pressure of the dry and wet combined cooling system is reduced by 2.6 k Pa compared with the direct air cooling system. When the unit exhaust gas volume is increased by 100% from 70%, the backpressure is increased by 2.7 k Pa, while the steam distribution of the water cooling system is increased from 10.7% to 13.9%; when the cooling water volume of the water cooling system is increased from 4000 t/h to 12000 t/h,the back pressure drops by 0.9 k Pa, the steam distribution of the water cooling system increases from 9% to 13.9%; when the ambient temperature rises to 35℃, the back pressure of the dry and wet combined cooling system is 10.7 k Pa lower than that of the pure air cooling system; When the fan speed of the air cooling system increased from 60% to 100%, the back pressure decreased by 6.3 k Pa, while the steam distribution of the water cooling system decreased from 22.9% to 13.9%.