某核电厂满负荷甩孤岛试验跳机问题的分析与处理

Analysis and Solution for Turbine Trip Problem during Full Power House Load Test at a Nuclear Power Plant

介绍了某核电厂满负荷甩孤岛试验过程中汽轮机轴向位移保护动作的跳机问题。通过分析和检查,得出了跳机的直接原因是2号中压调节阀门在试验过程中发生机械卡涩,蒸汽意外进入中压缸做功,产生额外轴向推力造成汽轮机轴向位移测量值超过停机保护阈值,触发跳机;根本原因是中压调节阀门止推环装配间隙设计值偏小的结论。根据跳机问题产生的原因,现场统一对中压进汽阀门进行了处理或预防性改造。改造完成后,再次试验时阀门动作合格,机组满负荷甩孤岛试验结果合格。

The paper introduces the axial displacement protecting action triggered turbine trip problem during the full power house load test at a nuclear power plant. Through analysis and inspection, The direct reason for turbine trip is that the second medium-pressure control valve was jammed during the test, hence steam entered the medium-pressure cylinder to work, which caused the extra axial thrust that result in the monitored value of axial displacement was higher than the protection threshold value to trigger the turbine trip. The root cause of the turbine trip is that the design value of the assembling interval of the thrust ring of the medium pressure control valve is too small.