Thermal power plants experience cycling duty leading to the fatigue of the boiler and heat exchanger tubes. As a result, tube failures occur frequently in coal fired fleets leading to forced outages. Because the tube leaks have been the major source of unwanted shutdowns and the number of outages is increasing, present work focuses on the detection and isolation of the leak in a subcritical boiler based upon the process data from a commercial coal-fired power plant. The mass balance equation around the steam drum was analyzed using timeseries data collected from a 300 MW power plant. The ratio of the feed water mass flow rate to the steam mass flow rate was defined as a key parameter for detecting leaks. The difference in slope between the feedwater and steam mass flow rate during the normal and faulty operations was established as the upper control limit for real time monitoring. To reduce false alarm rates that arise when raw signal is directly compared against the threshold due to common process fluctuations, an optimal filter was derived for smoothing. It was found that the optimal filter reacted much more quickly to process changes than an exponential moving average filter, around 8 hours earlier on average. Occurrence of relatively high false alarm rates even in the filtered responses was related to the cycling of the boiler from the base load condition. Variable threshold was established to keep false alarm rates to the minimum while maintaining the leak detection rate. Finally, the leak was located at the economizer and this could readily be isolated by investigating the magnitude of the mass flow rates ratio and the temperature at the economizer outlet.

火力发电厂经历循环运行，导致锅炉和热交换器管疲劳。结果，燃煤车队经常发生管子故障，导致被迫中断。由于管道泄漏一直是造成意外停机的主要原因，并且停机次数也在增加，因此，目前的工作重点是根据来自商业燃煤电厂的过程数据，对亚临界锅炉中的泄漏进行检测和隔离。使用从300兆瓦发电厂收集的时间序列数据分析了汽包周围的质量平衡方程。给水质量流量与蒸汽质量流量之比被定义为检测泄漏的关键参数。正常和故障操作期间给水和蒸汽质量流量之间的斜率差异被确定为实时监控的控制上限。为了减少由于常见过程波动而直接将原始信号与阈值进行比较时出现的误报率，推导了用于平滑的最佳滤波器。已发现，最佳过滤器对处理更改的反应比指数移动平均过滤器快得多，平均大约要早8个小时。甚至在过滤后的响应中也出现了较高的误报率，这与锅炉从基本负荷状态开始的循环有关。建立了可变阈值，以将错误警报率保持在最低水平，同时保持泄漏检测率。最后，