The present disclosure relates to a boil-off gas treatment system and method for a fuel cell electric vehicle, and a main object of the present disclosure is to provide a boil-off gas treatment system and method capable of safely and efficiently treating, storing, and utilizing vaporized hydrogen in a hydrogen tank for a fuel cell electric vehicle.

A mobile liquefaction plant (7) for liquefying helium, includes a liquefaction device (8) that liquefies helium, an intermediate storage tank (9) for liquefied helium, a cleaning device (29) which removes non-helium components from the helium and is connected upstream of the liquefaction device, and an additional collecting device (25) that collects gaseous helium which evaporates when an application cryostat (4) is filled with liquid helium and that includes a container (26) with a flexible wall and which stores the collected gaseous helium approximately at atmospheric pressure. The container (26) has an available container volume of at least 5 m.sup.3. Systems provided with such a mobile liquefaction plant exhibit an improved recovery of helium from application cryostats in a simple and cost-effective manner.

In a BOG treatment system, boil-off gas (BOG) discharged from a storage tank is compressed, most of the BOG is used as the fuel of vessel engines, and a remaining part of the BOG is liquefied by cold energy of BOG newly discharged from the storage tank and is returned to the storage tank, thereby efficiently utilizing the BOG. The BOG treatment system for a vessel includes a compressor compressing the BOG discharged from the storage tank; a medium pressure gas engine receiving at least a part of the BOG compressed by the compressor, as fuel; a heat exchanger exchanging heat between the remaining part of the BOG, which is not supplied to the medium pressure gas engine as fuel, and the BOG, which is discharged from the storage tank and is not compressed; and an expander decompressing the remaining part of the BOG cooled by the heat exchanger.

A system and method is provided for transferring liquid argon from a bulk storage tank to a transport tank in which liquid argon is pumped through a tube arrangement within a heat exchanger and the tube arrangement is contacted by liquid nitrogen at a temperature less than the temperature of the liquid argon so that heat transfers from the liquid argon to the liquid nitrogen, thereby reducing the temperature, density and pressure of the liquid nitrogen prior to exiting the heat exchanger.

A method (40) for detecting any throttling losses (11) in a hydrogen tank system (10), characterized by the following features: before access to the hydrogen tank system (10), a course (30) of pressure and temperature (31) expected for the access without the throttling losses (11) is determined at different measuring points in the hydrogen tank system (10), the pressure and the temperature (31) at the measuring points are continuously recorded during the access, and the throttling losses (11) are detected on a case-by-case basis on the basis of the deviation (33) of the pressure or the temperature (31) from the expected course (30).