600MW汽轮发电机组轴系标高测试及振动故障治理

某电厂一台600MW汽轮发电机组存在严重的振动不稳定隐患,在机组带负荷过程中,5号、6号轴振出现了突发性的17.5Hz低频振动,幅值分量达170μm。通过对该机组轴系相对标高变化、振动和油膜压力的测试分析,得出轴系标高不合理是导致机组振动失稳的主要原因之一。介绍了机组振动测试情况和轴系标高测试试验方法,结合标高检测结果,分析了该机组轴系标高随工况的变化规律。测试结果表明,从冷态到热态,4号轴承标高相对5号轴承抬高达1.180mm。经综合分析,制定并实施了冷态下轴系标高调整方案,5号轴承相对4号轴承抬高0.9mm,彻底解决了该机组轴系振动不稳定问题。

Shafting Elevation Measurement and Vibration Troubleshooting of a 600 MW Turbo-generator Unit

There exists a serious hidden trouble capable of causing an unstable vibration in a 600 MW turbo-generator unit of a power plant. During the load carrying period of the unit, a low frequency vibration at 17.5 Hz suddenly occurred to shaft No.5 and 6 with an amplitude component equaling to 170 μm. A measurement and analysis of the change of the relative levation, vibration and oil film pressure of the shafting system of the unit have induced one to conclude that the irrational elevation of the shafting system constitutes one of the main causes leading to an unstable vibration of the unit. The authors described the vibration measurement conditions of the unit and the methods for measuring and testing the shafting elevation. In conjunction with the measurements of the elevation, the law governing the change of the shafting elevation with the perating condition was analyzed. The measurement results indicate that from the cold state to the hot one, bearing No.5 is relatively elevated by 1.180 mm in comparison with bearing No.4. After a comprehensive analysis, a shafting elevation adjustment version was worked out and implemented in the cold state. Bearing No.5 was elevated by 0.9 mm relative to bearing No.4, thereby thoroughly solving the unstable vibration problem of the hafting system.