自然通风冷却塔运行实测与模拟

Testing and numerical simulation of natural draft cooling tower

通过对某150MW机组的自然通风冷却塔进行实际测试,得到该冷却塔的热质交换效率与系数,并发现其运行过程中的一些问题及性能优化方向;基于此,采用微元差分法对该冷却塔的雨区和填料区进行温度及压力分布的数值模拟。结果表明:在该冷却塔的填料厚度为3.0m时,其仅贡献42.1%的温降却需要损耗55.8%的空气压降,冷却塔最优填料厚度约为2.5m;该机组的最优循环冷却水泵运行策略为1泵拖2塔,此时冷却塔的湿球效率可达75.0%,机组净发电量比其他循环冷却水泵运行策略多3.007 MW。

Through practical measurement on a natural draft cooling tower in a 150 MW unit,the efficiency and coefficient of heat and mass transfer in the tower were obtained,and several problems during the tower operation and its performance optimization direction were found.On this basis,the temperature and pressure distribution in rain area and filling area of the cooling tower were numerically simulated.The results show that,with the filling material thickness of 3.0minside the cooling tower,42.1% temperature drop needs 55.8% pressure loss,and the optimum thickness of the padding is around 2.5m.The optimum operation strategy of this circulating cooling water pump is one pump with two towers,and the wet bulb efficiency of the cooling tower can reach 75.0%,the net power generation can increase by 3.007 MW compared with the unit using two pumps with one tower strategy.