| 摘要 |
PROBLEM TO BE SOLVED: To provide a BOG liquefying device for a liquefied gas tank to keep a condensation pressure (temperature) at a given value even when an amount of BOG generated in the liquefied gas tank is fluctuated. SOLUTION: BOG from a liquefied gas tank 1 is boosted by a compressor 3 and guided to a condensation container 4 and cooled and liquefied by a heat- exchange tube 5 to produce liquefied BOG which is stored in the condensation container 4. Liquefied BOG immerses a part of the heat-exchange tube 5. The heat-exchange tube 5 has an exposure part above the liquid level of the liquefied BOG and forming a substantial heat transfer area to the BOG. Since, when an amount of the BOG is decreased, the heat transfer area of the heat-exchange tube 5 is relatively increased to a value higher than a value heretofore available, a condensation amount is increased and a pressure in the condensation container 4 is lowered. In which case, the liquefied BOG in a liquid receiving container 10 is sucked up in the condensation container 4 through a siphon tube 9 and the liquid level of the liquified BOG in the condensation container 4 is raised. A part of the heat-exchange tube 5 heretofore exposed is sunk under the liquid level of the liquefied BOG. Thus, a heat transfer area is decreased and a condensation pressure is kept at a given value.
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