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研究压水堆核电厂卧式12级单吸中开筒袋式离心上充泵(RHM100-205.12)汽蚀的典型振动特征、产生原因及解决方案。上充泵上充工况运行时存在异常振动波动且波动幅度超过国标规定的报警值。监测发现上充泵的振动时域信号中存在明显瞬间冲击,频域信号中存在叶片通过频率等谐波分量与宽带噪声,诊断首级叶轮处产生汽蚀,大修解体检查确认首级导叶顶部叶片前缘处被汽蚀严重破坏。上充泵汽蚀的产生,主要原因是汽蚀安全余量k值偏小。现场试验表明改变首级导叶叶片前缘与叶轮叶片尾缘间径向间隙能极大影响汽蚀程度,可用于提高k值。将间隙扩大1 mm后,汽蚀破坏显著改善。研究表明:监测RHM型上充泵入口侧垂直方向振动测点的典型振动特征可简易诊断汽蚀故障;扩大首级导叶叶片与叶轮叶片间径向间隙能有效缓解汽蚀。
This paper studies the typical vibration characteristics, causes and solutions of cavitation cavitation in open type bag centrifugal centrifugal pump (RHM100-205.12) in horizontal type 12 single suction in PWR NPPs. On the filling pump operation conditions when there is abnormal vibration fluctuations and fluctuations exceeding the national standard alarm value. The monitoring showed that there was obvious instantaneous impact in the vibration time-domain signal of the charging pump. The frequency-domain signal existed the harmonic components such as the frequency of the blade and the broadband noise. The cavitation erosion was detected in the first stage impeller. The leading edge of the blade is seriously damaged by cavitation. Cavitation on the pump charge generated, the main reason is the value of the safety of cavitation k k value is too small. Field tests show that changing the radial clearance between the leading edge of the vane of the first stage and the trailing edge of the impeller can greatly affect the cavitation degree and can be used to increase the k value. After expanding the gap by 1 mm, the cavitation damage is significantly improved. The results show that the typical vibration characteristics of the vibration measuring points on the inlet side of RHM type charge pump can be easily diagnosed by cavitation faults. Expanding the radial clearance between the first stage vane and the impeller can effectively relieve the cavitation erosion.