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An Examination on the Dispersion Characteristics of Boil-off Gas in Vent Mast Exit of Membrane Type LNG Carriers

멤브레인형 LNG선박 화물탱크 벤트 마스트 출구에서의 BOG 확산 특성에 관한 연구

  • Received : 2013.03.14
  • Accepted : 2013.04.25
  • Published : 2013.04.30

Abstract

Liquefied gas carriers generally transport cargoes of flammable or toxic nature. Since these cargoes may cause an explosion, fire or human casualty, the accommodation spaces, service spaces and control stations of liquefied gas carriers should be so located as to avoid ingress of gas. For this reason, the paragraph 8.2.9 of IGC Code in IMO requires that the height of vent exits should be not less than B/3 or 6 m whichever is greater, above the weather deck and 6 m above the working area and the fore and aft gangway to prevent any concentration of cargo vapor or gas at such spaces. Besides as known, the LNG market has been growing continually, which has led to LNG carriers becoming larger in size. Under this trend, the height of a vent will have to be raised considerably since the height of a vent pipe is generally decided by a breadth of a corresponding vessel. Accordingly, we have initiated an examination to find an alternative method which can be used to determine the safe height of vent masts, instead of the current rule requirement. This paper describes the dispersion characteristics of boil-off gas spouted from a vent mast under cargo tank cool-down conditions in the membrane type LNG carriers.

Keywords

LNG carrier(Liquefied natural gas carrier);IGC code(International Gas Carrier Code);Gas dispersion;BOG(Boil-off Gas);CFD

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