某超临界机组轴向位移保护动作跳机分析及处理

Analysis and Treatment of Axial Displacement Protection Action for a Supercritical Unit

某超临界机组在正常运行中,汽轮机突然跳闸,机组停运,跳闸首出为轴向位移保护动作。基于相关参数变化趋势,排除了轴向位移保护误动的可能,确认汽轮机跳闸时轴向位移实际已发生突变。综合跳闸前后高压调节阀开度、功率、调节级压力、调节级温度等多参数的特性和变化趋势,判定汽轮机轴向位移突变是由于汽轮机运行中进水所致,再对相关运行参数的历史数据进行追溯,发现该机组已发生多起类似进水事故。结合现场汽轮机导汽管布置、调节阀结构、阀门管理曲线及运行方式,详细分析了汽轮机进水的来源及原因,最终确认汽轮机进水是由于导汽管积水所致。针对该问题制定了汽轮机防进水措施,电厂按照措施处理后,未再发生过类似事故。

During the normal operation of a supercritical unit,the steam turbine suddenly tripped, the first trip-out was axial displacement protection action. Based on the variation trend of relevant parameters, this paper excludes misoperation of axial displacement protection, and confirms that axial displacement has been changed when the steam turbine trips. Based on the characteristics and changing trend of the high-pressure adjusting valve opening degree, power,pressure of governing stage, temperature of governing stage and other parameters before and after tripping, it is concluded that the change of axial displacement of steam turbine is caused by water induction during the operation of the unit, and similar accidents of turbine water induction have occurred several times. Combining with the arrangement of the steam guide pipe, the structure of the regulating valve, the management curve of the valves and the operation mode of the steam turbine, the source and cause of turbine water induction are analyzed. It is finally confirmed that the water comes from the accumulated water in the steam guide pipe. In view of this problem, the prevention of water induction into steam turbine measures have been formulated, and no similar accidents occurred in the unit after the treatment according to the measures.