Device and method for liquefying a fluid such as hydrogen and/or helium

A device for liquefying a fluid such as hydrogen and/or helium, the device comprising:

• a circuit for fluid that is to be cooled having an upstream end configured to be connected to a source of gaseous fluid and a downstream end configured to be connected to a member for collecting the liquefied fluid;
• an assembly of heat exchanger(s) in a heat exchange relationship with the circuit for fluid that is to be cooled;
• and
• at least one first cooling system in a heat exchange relationship with at least part of the assembly of heat exchanger(s), the first cooling system comprising a refrigerator that is configured to perform a refrigeration cycle on a cycle gas comprising primarily of helium,
• wherein said refrigerator comprises the following disposed in series in a cycle circuit:
• a compression mechanism configured to compress the cycle gas,
• at least one cooling member configured to cool the cycle gas,
• an expansion mechanism configured to expand the cycle gas, and
• at least one heating member configured to heat the expanded cycle gas,
• wherein the compression mechanism comprises at least four compression stages in series composed of an assembly of compressor(s) of the centrifugal type, the compression stages being mounted on shafts that are driven in rotation by an assembly of motor(s),
• wherein the expansion mechanism comprises at least three expansion stages in series composed of an assembly of turbines of the centripetal type,
• wherein the at least one cooling member is configured to cool the cycle gas at the outlet of at least one of the turbines, and
• wherein at least one of the turbines is coupled to the same shaft as at least one compression stage so as to supply mechanical work produced during the expansion to the compression stage,
• wherein the device comprises more compression stages than turbines, wherein each turbine is coupled to the same shaft as a single respective compression stage driven by a respective motor, wherein the other compression stages that are not coupled to a turbine are mounted only on rotary shafts driven by separate respective motors,
• wherein the compression stages that are coupled to a turbine and the compression stages that are not coupled to a turbine alternate in series in the cycle circuit.