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Research Papers: Gas Turbines: Turbomachinery

Physical Analysis of Rotor-to-Stator Rub in a Large-Capacity Low-Pressure Steam Turbogenerator

[+] Author and Article Information
Seogju Cha

Department of Mechanical Engineering,
Korea University,
1 ga, Anam-dong, Seongbuk-gu,
Seoul 136-713, South Korea
e-mail: chaseog@naver.com

Sungsoo Na

Professor
Department of Mechanical Engineering,
Korea University,
1 ga, Anam-dong, Seongbuk-gu,
Seoul 136-713, South Korea
e-mail: nass@korea.ac.kr

1Corresponding author.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received April 27, 2015; final manuscript received December 19, 2015; published online February 17, 2016. Editor: David Wisler.

J. Eng. Gas Turbines Power 138(7), 072605 (Feb 17, 2016) (6 pages) Paper No: GTP-15-1147; doi: 10.1115/1.4032415 History: Received April 27, 2015; Revised December 19, 2015

Excessive vibration in large-capacity turbine generators can lead to expensive repairs and downtime with associated loss of operational income. Therefore, it is vital to detect the rubbing location in the rotor system at an early stage. The challenge is in achieving this without the expense and labor of complete disassembly. In this study, we present a practical tool for estimating the rubbing locations in a large-capacity rotor system from the shaft vibration patterns at each bearing. The measurement and analysis were performed on the rotor system of an 800-MW class large-capacity turbine generator. Three vibration patterns were observed in the machine operating on-site and were explained in terms of vibration modal analysis and the unbalance response characteristics to identify the rubbing locations. These results will be of interest to industrial engineers and have the potential to increase savings in operation costs.

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References

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Figures

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Fig. 1

The shaft supporting condition

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Fig. 2

The rotor shaft elliptical vibration

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Fig. 3

Lateral vibration of a beam element

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Fig. 6

Vibration components in the x-direction

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Fig. 5

Machine train diagram and the pickup positions

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Fig. 4

A large turbine generator

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Fig. 7

Vibration patterns of an 800-MW turbine generator due to rubbing (∠ is the phase angle (deg) and - is the amplitude (0-to-peak, μm)): (a) pattern A, (b) pattern B, and (c) pattern C

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Fig. 8

Unbalance positions and vibration magnitudes

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Fig. 9

Vibration responses due to rubbing: (a) pattern A, (b) pattern B, and (c) pattern C

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