• 제목/요약/키워드: 최종단 회전익

검색결과 4건 처리시간 0.016초

30MW 증기터빈 최종단 회전익 파단 사고 분석 (A Failure Analysis on the Broken Last Blade of 30MW Steam Turbine)

  • 김성봉;김인철;한승우;전채홍
    • 동력기계공학회지
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    • 제11권1호
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    • pp.5-15
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    • 2007
  • In the recently released accident-investigation report on blade failure, almost 70% of blade failures was found at low pressure turbine blades, and it is well known that main cause is due to the vibration modes. This paper describes the systematic approach on the root cause of the blade failure at L 0 stage, 30MW single flow industrial steam turbine which had tripped by high vibration after ten-month commercial operation. A fracture was found at the only one damping wire hole of 59 blades, and crack was detected at three damping wire holes by NDT. According to the analysis result for the crack fracture surface and the chain of the sequential operational events, we come to the conclusion that a typical high cycle fatigue is the most dominant factor caused to the blade failure, the resonance frequency margin was narrowed by the cut damping wire and the high cycle vibration was amplified, and then the blade was broken at once by the centrifugal force when the crack reached the critical size.

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터빈 운전 신뢰성 향상을 위한 응력부식균열 평가 (The Evaluation of the Stress Corrosion Cracking for Improvement of Reliability in Turbine Operation and Maintenance)

  • 강용호;송정일
    • 한국태양에너지학회:학술대회논문집
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    • 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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    • pp.280-287
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    • 2008
  • In case of low pressure steam turbine used in power plant, it was operated in wet steam and high stress condition. Therefore, it is possible that the corrosion damage of low pressure was induced by this condition. According to previous study, about 30% of total blade failure correspond to corrosion fatigue or SCC(stress corrosion cracking) in low pressure turbine. Especially, LSB(last stage bucket) of low pressure turbine has a higher hardness to prevent erosion damage due to water droplet however, generally this is more dangerous for SCC damage. Therefore, to improve reliability of turbine blade. various methods for SCC evaluation has been developed. In this study, the crack found in LSB during in-service inspection was evaluated using microstructure analysis and stress analysis. From the stress analysis, the optimum size of fillet to remove the crack was proposed. And also, the reliability was evaluated for modified LSB using GOODMAN diagram.

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