Turbine
and Compressor Vibration Encountered at Startup of a Methanol
Plant J. C. Wachel, AICHE Ammonia and Related
Plants Safety Symposium, Minneapolis, MN, August 26-30,
1972 .
This paper discusses several types of vibration and failure problems
which occurred in a steam turbine-compressor string in a methanol
plant resulting in considerable downtime of the process. The vibrations
which occurred are representative of those which can occur in most
modern high speed installations. By using new and effective ways
of presenting data utilizing signature analysis techniques, the
causes of the excessive vibrations and failures were established.
Vibrations encountered were caused by 1) unbalance, 2) misalignment,
3) mechanical resonances of attached structural components, 4) running
near critical speeds, 5) sleeves which shifted during operation,
6) nonsynchronous instabilities, and 7) intermittent faulty operation
of governor control and overspeed trip. The nonsynchronous instabilities
caused several compressor failures, even though tilted pad bearings
were used to eliminate instabilities.
By monitoring
and recording vibration data on startups, it was possible to replay
and study transient vibration phenomena which typical control
board instruments cannot accurately display. The spectral time
history plots and diagnostic techniques presented in this paper
can be used to identify similar vibration problems on other units.
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