Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Study on Flow Characteristics and Discharge Coefficient of Safety Valve for LNG/LNG-FPSO Ships

LNG / LNG-FPSO 선박용 안전밸브의 유동특성 및 유출계수에 관한 연구

  • Kim, Sung-Jin (Dept. of Creative Engineering System, Pusan Nat'l Univ.) ;
  • Jung, Sung-Yuen (Research Institute of Mechanical Technology, Pusan Nat'l Univ.) ;
  • Kim, Dang-Ju (Research Institute, Korval Co., Ltd.) ;
  • Kim, Chul (Research Institute of Mechanical Technology, Pusan Nat'l Univ.)
  • 김성진 (부산대학교 창의공학시스템학과) ;
  • 정성윤 (부산대학교 기계기술연구원) ;
  • 김당주 ((주)코밸 연구소) ;
  • 김철 (부산대학교 기계기술연구원)
  • Received : 2010.09.06
  • Accepted : 2011.02.25
  • Published : 2011.05.01
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Abstract

The safety valve used in LNG/LNG-FPSO ships plays an important role in maintaining a fixed level of pressure by emitting LNG gas out of the pipes in the LNG piping system. The discharge coefficient is regarded as the most important factor in the valve performance. To satisfy the ship's classification, the discharge coefficient of the safety valve must usually be over 0.8. Despite the importance of understanding the flow phenomena inside the safety valve, the valve design is usually based on experience and experiments. We carried out a computational fluid dynamics (CFD) investigation using the ANSYS-CFX software. We observed the flow phenomena inside the valve and measured the discharge coefficients according to changes in the valve lift, which is the distance between the exit of the nozzle and the lower part of the disc plate. We verified our CFD results for the discharge coefficients using available experimental data.

LNG / LNG-FPSO선박에 사용되는 안전밸브는 배관 시스템으로부터 유체를 방출하여 시스템의 압력을 일정하게 유지시키는데 중요한 역할을 한다. 이러한 안전밸브의 기능적 특성으로 인해 유출계수는 밸브의 성능 중 가장 큰 비중을 차지하며, 선급의 인정을 받기 위해서는 0.8이상의 유출계수가 요구되고 있다. 밸브 성능을 향상시키기 위해서 밸브 내부에서 발생하는 유동특성에 대한 정확한 이해가 필요함에도 불구하고 대부분의 밸브 설계의 경우 현장 작업자들의 경험과 실험에 의한 시행착오에 의존하고 있다. 본 논문에서는 안전밸브에 대한 유동해석을 통해 밸브 내부에 발생하는 압축성 유동현상을 고찰하였고, 실험과 해석에 의한 유출계수를 비교하여 유동해석의 타당성을 검증하였으며, 안전밸브를 지나는 공기의 질량유량을 예측하기 위한 유동해석 모델을 확립하였다.

Keywords

References

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