火电湿冷机组通常采用真空严密性试验对机组负压系统的严密性进行评价，该方法可以有效评价平均负荷率大于80％的机组负压系统的泄漏率，并使机组经济性得到保证.但是，对于调峰尤其是深度调峰运行的机组，现有的行业标准并未对低负荷工况下机组的真空严密性评价方法做出规定.机组调峰运行处于低负荷阶段时，凝汽器热负荷、进入系统的空气总量、负压系统容积和真空抽吸装置的容量变化等均会对真空严密性的合格值造成不同程度的影响.对此，以某超临界350 MW 机组为例，探讨了在调峰低负荷区域时机组真空严密性的定性评价方法以及针对上述影响因素的定量修正方法，得出该机组在60％负荷下对应的真空严密性合格标准为304 Pa/min.该方法实用性强、评价方法简洁，可为调峰运行已经成为常态的火电湿冷机组的日常负压系统评价提供依据.%The vacuum tightness test was always used to evaluate the vacuum system's tightness for thermal power units with wet cooling.This method can evaluate the vacuum system's leakage rate effectively for u-nits with average load rate of more than 80%,which ensures the unit economy.However,for units suffer-ing from peak load operation,especially deep peak regulation,the existing industry standards have no spe-cific rules on vacuum tightness evaluation methods for units under low load conditions.When the units are during peak load operation with low load,the condenser heat load,air entering the system,vacuum system and the total volume of vacuum suction device capacity changes will all affect the qualified value of vacuum tightness,to different degrees.Therefore,taking a supercritical 350 MW unit as an example,the qualitative evaluation method at low load of peak shaving and the quantitative correction methods considering the a-bove factors were discussed.The results show that the qualified standard of the vaccum tightness of this u-nit under 60% load condition is 304 Pa/min.This method is simple and has strong practicality,which can provide references for wet cooling units for which peak load operation has become norm state.
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