Converting Journal Bearings to Tilting Pad Bearings to Control Oil Whip & Vibration in a Gas Turbine Tony Dzubay Rochester Public Utilities E & O TECHNICAL CONFERENCE Memphis, Tennessee April 20, 2005

History RPU - SWPC 251 B-2 Built 1974, Low Hours Controls and Equipment Upgrade 2001 Dual Fuel, Simple Cycle, Peaking, Black Start, 30MW

Reason for Concern Vibration –1 st -Critical Trips –Unpredictable Online Trips –High Average Not Seen Before –New Control/Vibration System Bentley Nevada 3300

Vibration & Exh Brg Supply Temp 60 minutes, 6MW

Trip Caused by Vibration 30 minutes, 6MW

Reasons for Vibration Oil Whip/Whirl Journal Bearing Design Cold Oil Tight Clearances

Initial Attempts to Remedy Balance Move #1 –Turbine Center Plane –Turbine Inlet Plane Verify/Modify Vibration Trip Limits –<95% speed – Alarm 7.0mils Trip 10mils Delay 3.0sec –>95% speed – Alarm 3.5mils Trip 5.0mils Delay 3.0sec Balance Move #2 –Generator N.E.E. –Filtered Vibration Analyses Rotor Unbalance 0.7 mils Oil Whip 0.5 – 3.0 mils

Initial Attempts to Remedy cont’d Check Mechanical Components –Exhaust Manifold Spring Hanger –Turbine Trunions

Possible Solutions Warmer Oil Refurbish Original Bearings –Overhaul in 1991 Show Dimensions Acceptable Modify Original Bearings –160 degree to 90 degree arc of contact –Increase in Babbitt Temps –Oil Coolers had Trouble in Past Install Tilting Pad Bearing

Tilting Pad Bearing Design Kingsbury Four-Pad Design Type of Pad - Pivot Point

Bearing Installation Ease of Installation Took 10 Days Tools Used Roll old Bearing Out, Roll New In Three SWPC Staff + One RPU

Tilting Pad Bearing Performance 60 minutes, 6MW

With New Bearing Installed Another Balance Move Lower Bearing Drain Temps Exhaust Bearing Much Lower Inlet Vibration Increased Generator N.E.E Increased –Not enough to Cause Concern Able to Hot-Start Unit

Other Benefits Audit of Other Equipment Need to Install New Seals Next Outage

Questions