Motor-Generator
Vibration Problems Encountered When Restaging an FCCU Turboexpander
F. R. Szenasi, 2nd International Turbo-Expander Users'
Council, Houston, TX, May 24-27, 1993.
This paper describes the solution of a vibration problem which resulted
from the conversion of a single-stage power-recovery turbo expander
train in an FCCU to a two-stage turbo expander. Details of the equipment
rain and operating speeds are given in Figure 1. During the startup
of the upgraded expander train, high vibrations (in excess of 10
mils peak-peak) were experienced by the motor-generator. These high
vibrations caused the unit to shut down as soon as it reached rated
speed.
Because of
high vibrations, the train was not able to operate for any length
of time; however, it was operated long enough to obtain data to
balance the motor-generator to allow further investigation of
the problem. Accelerometers and permanently installed proximity
probes were used to obtain the vibration data to determine the
location of the critical speeds of the motor, one of which was
near the operating speed. The motor-generator was field balanced
to allow operation until a long-term solution could be developed
.
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