某项目冷却水泵汽蚀余量分析及探讨
Analysis and discussion of net positive suction head of cooling water pump in a project
摘要：
对某项目不同方案的冷却水泵的汽蚀余量进行了分析和探讨，指出在当地大气压和输送液体温度已定的情况下，汽蚀余量的影响因素为冷却水泵入口与冷却塔底盘液面的高差和两者之间的管路阻力。提出了采用压出式冷却水泵安装方式，以及把冷却塔布置在裙房或塔楼屋顶，利用建筑本身的高度有效克服管路阻力、避免汽蚀现象的措施。建议水管控制流速不大于3 m/s，单个弯头局部阻力（水头）小于等于0.5 m。
Abstract：
This paper analyses and discusses the net positive suction head (NPSH) of different schemes of the cooling water pump of a project， and points out that the influencing factors of NPSH are the height difference between the inlet of the cooling water pump and the liquid level of the cooling tower bottom tray and the pipeline resistance between them when the local atmospheric pressure and the temperature of the transmitted liquid have been determined. This paper proposes the installation method of press-out cooling water pump, and the arrangement of cooling towers on the podium or the tower roof to effectively overcome the pipeline resistance and avoid cavitation by using the height of the building itself. It is recommended that the flow rate of the water pipe is not be greater than 3 m/s, and the local resistance (water head) of a single elbow is less than or equal to 0.5 m.
Keywords:net positive suction head; cooling water pump; press-out installation; local resistance; scheme optimization; velocity control