火力发电厂凝汽器负压水锤防护措施的计算研究

Calculation and Study on Protective Measures for Negative Water Hammer of Condensers in Thermal Power Plant

对于单机容量为600 MW以上的火电机组,当循环水系统出现事故停泵工况时,水力过渡过程持续的时间长、波动幅值大,其中凝汽器出口可能产生对系统危害最大的负压水锤。通过采用特征线法,建立循环水水流运动方程和连续方程;分析凝汽器负压水锤的产生机理,研究阀门关闭规律对凝汽器出口负压等主要参数的影响。结论表明:在水泵出口阀最优关闭规律下,采取调压的防护措施控制凝汽器负压水锤,工程上易于实现,可有效避免凝汽器出口的“液柱分离—弥合水锤”现象,有利于汽轮发电机组的安全稳定运行。

For thermal power units with a single unit capacity of more than 600 MW,when the circulating water system has an accidental pump shutdown condition,the hydraulic transition process lasts for a long time and the fluctuation amplitude is large.The outlet of the condenser may produce negative pressure water that is most harmful to the system.In this paper,the characteristic line method is used to establish the motion equation and continuous equation of circulating water flow.The mechanism of negative pressure water hammer of condenser is analyzed,and the influence of valve closing law on main parameters such as negative pressure at the outlet of condenser is studied.The conclusion shows that:under the optimal closing law of the pump outlet valve,the protective measures of pressure regulation are adopted to control the negative pressure water hammer of the condenser,which is easy to realize in engineering,and can effectively avoid the separation of the water column at the outlet of the condenser and bridge the water hammer,which is beneficial to safe and stable operation of the steam turbine generator set.