660MW超超临界机组“高加假切除”引发MFT原因分析及改进

Analysis and Improvement of MFT Caused by "False High Pressure Heaters Cut-off" of 660MW Ultra Supercritical Unit

高负荷高加全切后的抢救操作属电厂的成熟操作,但对高加全切瞬间重新开启高加抽汽管道的阀门试图再次投入高加而形成的"高加假切除"现象所导致的事故案例的报道较少。对调试期某660 MW超超临界机组满负荷下一次"高加假切除"引发的锅炉MFT事故的经过进行了详细的记录及原因分析,指出给水流量不足是该事件发生的根本原因,并对该事件的处理过程提出了针对性的改进方法,有效地消除了机组高负荷运行时的安全隐患,可为同类机组的设计、调试及运行提供参考。

The rescue operation after full cut of high pressure heaters is a mature operation of power plant under the condition of high load. However, there are few reports on the accident cases caused by the phenomenon of "false high-pressure heaters cut-off" caused by reopening the valves of high-pressure heater inlet pipes at the moment of full cut-off. A detailed record and cause analysis is made on the MFT accident of a 660 MW ultra supercritical unit under full load caused by "false high pressure heaters cut-off". It points out that insufficient feed water flow is the root cause of the accident, and puts forward targeted improvement methods for the treatment process of the accident, which effectively eliminates the hidden danger of safety during high load operation of the unit, and can be used for reference for the design,commissioning and operation of similar units.