核电厂柴油发电机组燃油系统压力异常问题原因分析及处理

Cause Analysis and Treatment of Abnormal Pressure in the Fuel System of Diesel Generator Sets in Nuclear Power Plants

核电厂的柴油发电机组是在核电机组丧失正常交流电源的事故工况下,为机组安全相关功能或纵深防御功能提供备用电源的设备,具有保障核安全相关功能或纵深防御功能。在机组正常运行工况下,柴油发电机组需处于可以随时启动的热备用状态。柴油发电机组的燃油系统为柴油机的启动和运行提供燃油,若燃油系统异常,会直接造成柴油发电机组不可用。某核电厂柴油发电机组在进行检修后的功能试验期间,出现燃油系统的进机压力异常波动现象,造成机组无法恢复在线备用。文章针对此故障问题建立故障树进行分析,制订并实施故障排查方案。通过故障排查确定,由于高压油泵压力脉冲的存在,燃油管道内部存在压力波叠加情况。随着柴油机长期运行造成的高压油泵磨损,高压油泵产生的压力脉动特性发生变化,造成特定位置的压力波存在异常的高峰和低谷。为恢复柴油发电机组可用,通过在压力变送器仪表引压管线增加缓冲盘管的方式消除压力波动现象,同时对柴油发电机组的后续运维要求和设计优化提出了改进建议。

The diesel generator set of a nuclear power plant is a device that provides backup power for the safety related or defense in depth functions of the unit in the event of an accident where the nuclear power unit loses normal AC power,and undertakes nuclear safety related or defense in depth functions.Under normal operating conditions,the diesel generator set must be in a hot standby state that can be started at any time.The fuel system of the diesel generator set provides fuel for the start and operation of the diesel engine.If the fuel system is abnormal,it will directly cause the diesel generator set to be unavailable.During the functional testing of a diesel generator set in a certain nuclear power plant after maintenance,abnormal fluctuations in the inlet pressure of the fuel system occurred,causing the unit to be unable to resume online standby.This article establish a fault tree to analyze this fault issue,and develop and implement a fault troubleshooting plan.Through troubleshooting,it was determined that due to the presence of pressure pulses in the high-pressure oil pump,there is already a superposition of pressure waves inside the fuel pipeline.With the wear of the high-pressure oil pump caused by long-term operation of the diesel engine,the pressure pulsation characteristics generated by the high-pressure oil pump change,resulting in abnormal peaks and valleys of pressure waves at specific positions.To restore the availability of diesel generator sets,the phenomenon of pressure fluctuations was eliminated by adding buffer coils in the pressure transmitter instrument pressure pipeline.At the same time,improvement suggestions were proposed for the subsequent operation and maintenance requirements and design optimization of diesel generator sets.