| 摘要 |
PURPOSE:To remove hydrogen or the like from a refrigerated liquefaction device without suffering helium leakage and on a stable basis by providing a trap for collecting hydrogen or the like between a heat exchanger and a J-T valve and fitting the trap with a discharge valve. CONSTITUTION:A trap for collecting hydrogen is provided between a lowermost heat exchanger 7 and a J-T valve 8, the trap 20 is fitted with a discharge valve 21 and a heater 12' for heating the hydrogen adhered between the trap 20 and the J-T valve 8 and to this valve is provided. In normal operating condition, the hydrogen which has invaded helium is cooled, its liquefaction is commenced at an intermediate heat exchanger 5 and the hydrogen is frozen and attached between heat exchangers 6 and 7 and J-T valve 8. The hydrogen frozen and attached to a passage from the outlet of the trap 20 to the J-T valve 8 is gradually heated and thawed by the heater 12' provided therebetween so as to be received in the trap 20 for removal thereof, while the helium is performing the removal operation of the hydrogen when it is passing through a precooling bypass valve 24. After removal of the hydrogen causing hindrance to the helium passage, the precooling bypass valve 24 is closed and the J-T valve 8 is opened to cause a switching action to helium liquefaction to take place.
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