Inner bearing Outer & Thrust bearing TWO GASTURBINES DRIVING PROCESS COMPRESSOR Compre ssor EQUIPMENT TRAIN ARRNAGEMENT

Inner beari ng Outer & Thrust bearing

Train Arrangement RR-Avon gas generator aerodynamically coupled with Cooper Bessemer PT at both end of refrigeration compressor. Discussion Major Problem is high vibration in outer bearing which has fluid film bearings and orthogonal proximity probes set up. Keyphasor is not active due to non availability of notch in the installed spare rotor. but the equipment is connected with system 1 online monitoring. Vibration trend was steady and stable for more than 6 months, Due to ambient temperature rise ( 48 deg c) sudden peak in vibration noticed in Power turbine outer bearing from 0.7 mills to 2.2 mills. Rise in outer bearing sustains more than minutes. After the rise again it reaches the base line value and maintains on it. Event doesn't follow any particular time based cycle. Inner bearing followed that but resulted with slight rise also randomly noticed slight drop in amplitude while outer bearing vibration ramp up. No significant vibration changes observed in other (compressor, lead power turbine) bearings during high vibration of outer bearing and normal running. Vibration Spectrum clearly shows only 1x (70 %of direct value) of PT speed and smaller quantity of harmonics. And noticed significant rise in Process variables. All the process variables such as compressor load, Gas Generator fuel flow, EGT, bearing oil pressure, Temperature … trend checked no correlation to the event.

47 MIN 3 MIN STAY OUTER BRG VIBRATION TREND Y 0 deg X 90deg

Y 0deg

NOTE; random Drops in Inner bearing while rise in outer bearing