Investigation of a Rotordynamic Instability in a High

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Investigation of a Rotordynamic Instability in a High

Transcript Of Investigation of a Rotordynamic Instability in a High

Investigation of a Rotordynamic Instability in a High Pressure Centrifugal Compressor Due to Damper Seal Clearance Divergence
J. Jeffrey Moore, Ph.D. (‘91) Southwest Research Institute
April 11, 2019
Moore, J.J., Camatti, M., Smalley, A.J., Vannini, G.V., Vermin, L.L., 2006, Investigation of a Rotordynamic Instability in a High Pressure Centrifugal Compressor Due to Damper Seal Clearance Divergence, 7th International Conference on Rotor Dynamics, September 25-28, 2006, Vienna, Austria.

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compressors, reciprocating compressors, and small gas turbine engines

Case Study: Rotordynamic Instability

 Two body compression train driven by 10 MW Gas Turbine through a gearbox
 Gas gathering application that feeds large LNG plant in Nigeria
 LP compressor is a 8 stage back-to-back design and is drivethrough
 HP compressor is a 9 stage back-to-back design operating at about 10,000 rpm
 Total train pressure ratio is 48:1
 Instability experience on HP compressor during field start-up
Low Speed: 7585rpm

GAS TURBINE PGT10B

Gear Box

High Speed: 9198rpm

CE/ COLPCASING 2BCL458

CE/ COHPCASING 2BCL459/ A

Tripped on site

Original Compressor Seal Designs
 LP Compressor:
 Tooth-on-stator labyrinth seal at both impeller eye and center balance piston locations
 Shunt injection on center balance piston  No swirl brakes
 HP Compressor
 Honeycomb damper seal used at center balance piston with  No swirl brake or shunt injection on any seal
 Design of compressor predated more recent experience with adverse effects of damper seals
 Design Pressure  P1=22 bar (319 psi) P2=133 bar (1930 psi)
 Maximum Discharge Pressure  189 bar (2740 psi) (Maximum Continuous Speed & Near Surge)

Experience Chart

 LP and HP compressor plotted on Fulton experience chart  Both machines within experience limits

MCS / NC1

4
CRITICAL
3.5
3

LP unit

2.5 API level 1-2
2

GE experience limit

HP unit

1.5

SAFE REGION

WARNING

1

1

10

100

1000

Gas mean density (kg/m3)

Site Description
 Site located near the Niger Delta in Nigeria  Gas is used to feed large LNG plant  Instability not discovered until field start-up since units were not
full load tested at the factory
Rotordynamic InstabilitySpeedDesignFieldInvestigation