间接空冷塔部分冷却扇段关闭热力特性的数值研究

Numerical Simulation of Thermal Performance of Indirect Dry Cooling Tower Under Different Operation Modes of Sectors

以某600MW机组大型间接空冷塔为对象,分别建立了塔内循环水流量分配模型与空冷塔数值计算模型,针对冷却扇段全部投运、侧面扇段关闭和迎风扇段关闭这3种模式下,侧风对空冷塔热力性能的影响进行了数值模拟。结果表明,在小风速下,关闭侧面或迎风扇段后,其他扇段散热量较扇段全部投运时增加,而扇段内循环水温降有所下降。在大风速下,受塔内外复杂流场及扇段间相互作用的影响,扇段热力性能的变化不尽相同。综合空冷塔冷却效率和防冻需求,为机组经济安全运行提供了参考。

A 600MW dry cooling tower was taken as an example, and flow distribution model of circulating water and numerical model of the tower were established respectively. In order to research the effects of crosswind on thermal performance of the tower, numerical simulations were carried out in different conditions of all sectors operating, side sectors shut down and upwind sectors shut down. The results show that when side or upwind sectors are shut down, other sectors have higher heat rejection and lower temperature drop of circulating water compared with the way of all sectors operating at low wind speed. Whereas these sectors have different variation of thermal performance influenced by complex flow fields inside or outside the tower and the interactions between sectors at high wind speed. Meanwhile combining cooling efficiency and freezing prevention of the tower, instructional views are provided for the economical and safely operation of the unit.