Refrigeration cycle, freezer, liquefaction apparatus and method

Abstract

The present invention relates to a refrigerator including a refrigeration cycle for a cycle gas mainly containing hydrogen and / or helium, having a cycle circuit (12) including a cycle gas compression mechanism (21, 22), a cycle gas cooling member (23, 5), a cycle gas expansion mechanism (24, 25), and a member (5) for reheating the expanded cycle gas, wherein the compression mechanism includes at least one alternating volumetric compression stage (21) and at least two centrifugal compression stages (22) arranged in series, and the expansion mechanism includes at least two expansion turbines (24), at least one of the turbines (24) being mechanically coupled to the centrifugal compression stage (22) (122), and at least one alternating volumetric compression stage (21) being arranged in series with at least two centrifugal compression stages (22) and upstream of at least two centrifugal compression stages (22).

Description

Technical Field

[0001] The present invention relates to a refrigerator, a liquefaction device, and a method having a refrigeration cycle.

[0002] More specifically, the present invention relates to a refrigerator having a cycle for refrigerating a cycle gas mainly containing hydrogen and / or helium. The refrigerator has a cycle circuit including a mechanism for compressing the cycle gas, at least one member for cooling the cycle gas, a mechanism for expanding the cycle gas, and at least one member for heating the expanded cycle gas. The compression mechanism includes at least one compression stage of a positive displacement and reciprocating type and at least two centrifugal compression stages arranged in series. The expansion mechanism includes at least two expansion turbines of a centrifugal type, and at least one of the turbines is mechanically connected to the centrifugal compression stage so as to provide mechanical work generated during expansion to the compression stage.

Background Art

[0003] It is known to reclaim expansion work from a turbine to a centrifugal compressor. US Patent No. 2022390169A and International Publication No. 2022033714A1 pamphlet describe solutions for refrigerators.

[0004] However, known solutions are insufficient for, for example, large hydrogen liquefaction devices (low efficiency of centrifugal compression, low working pressure, low compression ratio, etc.).

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to overcome all or part of the drawbacks of the prior art described above.

Means for Solving the Problems

[0006] For this purpose, the freezer according to the present invention is essentially characterized by having at least one positive displacement reciprocating compression stage arranged in series upstream of at least two centrifugal compression stages, as otherwise defined in the general definition given in the above preface.

[0007] Furthermore, embodiments of the present invention have the following features, namely, - The compression mechanism has at least three centrifugal compression stages arranged in series. - The expansion mechanism includes at least two turbines, each mechanically connected to a centrifugal compression stage. - The compression mechanism has at least two compression stages, one positive displacement and the other reciprocating, arranged in series. - The expansion mechanism includes at least one Joule-Thomson type expansion valve arranged in series downstream of at least one of two expansion turbines. - At least one compression stage of the positive displacement and reciprocating type includes a piston compressor. - A piston compressor includes a piston that can move within a chamber for compressing cycle gas, an actuator for the piston and a system for drawing in cycle gas to be compressed into the compression chamber, a system for delivering the compressed cycle gas from the compression chamber, and members for controlling the intake system and / or delivery system to control the mass flow rate and / or compression rate of positive displacement and reciprocating compression stages. - The refrigerator has a system for regulating at least one of the expansion turbines, including a throttle valve at the inlet of the expansion turbine, and / or a system for diverting the fluid flow supplied to the turbine. - The control member controls the opening and closing of the expansion section of the compression chamber, and the expansion section can be activated to modify the mass flow rate that the piston compressor must compress. - A system for regulating at least one expansion turbine is configured to maintain the expansion rate determined at the turbine end. - The freezer includes a downstream compression regulating system configured to regulate at least two centrifugal compression stages arranged in series, the downstream compression regulating system including a system for diverting fluid flow supplied to all or part of the centrifugal compression stages, a frequency variable device associated with at least one of the centrifugal compression stages, and at least one inlet flow regulator ("IGV") for the gas flow supplied to at least one of the centrifugal compression stages. - The downstream compression control system controls the flow rate of the cycle gas in the centrifugal compression stage, and is configured to reduce the flow rate of the cycle gas in the centrifugal compression stage in response to a reduction in the flow rate of the cycle gas that can be contained in the turbine. - The cycle circuit includes a volume for attenuating pressure pulsations, such as a pressurized buffer storage device, which is arranged between the positive displacement and reciprocating compression stages and the centrifugal compression stage, and the attenuation volume is sized to reduce the pressure amplitude of the cycle gas between the outlet of one or more positive displacement and reciprocating compression stages and the inlet of the centrifugal compression stage to 1 / 10 to 1 / 100. - The cycle circuit does not have any components for cooling the cycle gas at the outlet of at least one of the centrifugal compression stages other than the last centrifugal compression stage. It may have one or more of these.

[0008] The present invention also relates to an apparatus for liquefying a supply fluid such as hydrogen and / or helium, comprising a circuit for the supply fluid having an upstream end intended to be connected to a supply gas source and a downstream end intended to be connected to a member for collecting the liquefied supply gas, wherein the apparatus comprises a set of heat exchangers that exchange heat with the circuit for the supply fluid, and the apparatus comprises at least one freezer that exchanges heat with at least a portion of the set of heat exchangers, the freezer being as described above or in any one of the following features.

[0009] According to other possible specific features, - In response to a signal representing a decrease in the thermal load of the supply fluid circuit, components for controlling the intake and delivery systems are configured to reduce the pressure and / or mass flow rate at the outlets of the positive displacement and reciprocating compression stages by modifying the mass flow rate and / or compressibility of the positive displacement and reciprocating compression stages, and the signal representing the decrease in the thermal load of the supply fluid circuit is supplied, for example, by components for determining the flow rate, and / or the characteristics of the supply gas flow of the device, and / or measured values ​​of the determined modification at the temperature of the cold end of the refrigerator cycle circuit for the same operation, and / or measured values ​​of the determined modification at the temperature of, for example, the downstream and upstream expansion of a set of heat exchangers in the supply fluid circuit for the same operation.

[0010] The present invention also relates to a method for liquefying a supply fluid, such as hydrogen, using a liquefaction apparatus having any one of the above or below features, the method comprising the steps of first compressing a positive displacement and reciprocating cycle gas, then compressing a centrifugal cycle gas, centrifugally expanding the centrifugalally compressed cycle gas, and recovering part of the centrifugally expanding work for centrifugal compression.

[0011] According to one possible specific feature, the method involves the steps of regulating the mass flow rate of the cycle gas compressed by positive displacement and reciprocating compression as a function of the heat load of the supply gas flow, and regulating the flow rate of the cycle gas in centripetal expansion and centrifugal compression as a function of the mass flow rate of the cycle gas compressed by positive displacement and reciprocating compression.

[0012] The present invention may also relate to any alternative apparatus or method that includes any combination of the above or below features of the claims.

[0013] Further specific features and advantages will become clear when you refer to the provided diagrams and read the following description.

[0014] This invention will be better understood by reading the following description, which is given merely as an example, and by referring to the accompanying drawings. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a schematic partial view showing the structure and an example of operation of a first example of a liquefaction apparatus equipped with a refrigerator according to the present invention. [Figure 2] Figure 2 is a schematic partial view showing a second example of the structure and operation of a refrigerator according to the present invention. [Figure 3] Figure 3 is a schematic partial view of details of a modification of a compression system that can be used in a refrigerator according to the present invention.

Embodiments for Carrying Out the Invention

[0016] Throughout the figures, the same reference numerals relate to the same elements.

[0017] In this detailed description, the following embodiments are examples. The description refers to one or more embodiments, but this does not mean that the features apply only to a single embodiment. The individual features of different embodiments can also be combined and / or replaced to provide other embodiments.

[0018] Figure 1 shows an exemplary embodiment of a refrigerator 2 having a cycle for refrigerating a cycle gas, for example mainly containing hydrogen and / or helium.

[0019] The refrigerator 2 has a cycle circuit 12 including mechanisms 21, 22 for compressing the cycle gas, at least one member 23, 5 for cooling the cycle gas, mechanisms 24, 25 for expanding the cycle gas, and at least one member 5 for heating the expanded cycle gas.

[0020] The cooling and heating of the cycle gas include, for example, a set of heat exchangers. For example, a plurality of heat exchangers are arranged in series, in which two separate sections of the cycle circuit simultaneously circulate in a countercurrent operation for the respective cooling and heating of the cycle gas. This plurality of heat exchangers forms a member for cooling the cycle gas and a member for heating the cycle gas.

[0021] As schematically shown, the compression mechanism includes at least one compression stage 21 of the positive displacement and reciprocating type (two stages in series in this example) and at least two centrifugal compression stages 22 (two stages in series in this example), which are arranged in series.

[0022] The expansion mechanism includes at least two expansion turbines 24 of the centripetal type (two in series in this example), at least one of which is mechanically connected to the centrifugal compression stage 22 so as to provide a compression stage 22 with mechanical work generated during expansion (in this example, the two turbines 24 are mechanically connected to the two centrifugal compression stages respectively). This mechanical connection is achieved, for example, by fixing the turbine and the compressor to exactly the same drive shaft. This constitutes a turbocompressor (that is, there is no motor for driving the compressor or other active elements that provide mechanical work to the compressor).

[0023] As shown, the turbines 24 in series are preferably connected from upstream to downstream respectively, and the compressors 22 are considered in reverse order (from downstream to upstream). This means, for example, that at least one turbine 24 is connected to a compression stage 22 that is placed upstream of the compression stage 22 to which another turbine 24 in the cycle circuit 12 is connected preferentially.

[0024] Each compression stage 21 of the positive displacement and reciprocating type may include a piston compressor or may be composed of a piston compressor. The compression ratio of the total compression is typically 10 to 30 between the upstream end and the inlet to the expansion turbine. The piston compressor 21 can reach a high pressure and the compression ratio is maximized. This relatively high compression ratio can be obtained with a relatively limited volume flow rate and good energy efficiency.

[0025] The number of compression stages 22 of the positive displacement and reciprocating type may be 1 to 8, for example 3 to 6.

[0026] The number of centrifugal compression stages 12 may be 1 to 8, for example 2 to 8.

[0027] Coolers 23 (heat exchangers for heat exchange between heat transfer fluids such as cycle gas / water) may be arranged at one or more outlets of the centrifugal compression stages 22, for example, at least the outlet of the last centrifugal compression stage (for example, to ensure isothermal or substantially isothermal compression, or to maintain a cycle gas temperature below a threshold of 65-70°C). This means that the cycle circuit 12 may not have any components for cooling the cycle gas at at least one outlet of the centrifugal compression stages 22 other than the last centrifugal compression stage 22.

[0028] This structure includes one or more positive displacement reciprocating compression stages 22 arranged in series upstream of the centrifugal compression stage 22, providing high energy efficiency to the freezer 2.

[0029] In detail, this structure allows for centrifugal overcompression of a relatively light cycle gas (e.g., hydrogen) pre-pressurized by a piston-type compressor 22. This makes it possible to relatively reduce energy consumption for the compression operation.

[0030] These two very different compression technologies (positive displacement piston and centrifugal radial) have characteristics (enthalpy as a function of flow rate) that make them difficult to combine. Specifically, reciprocating compressors create interruptions in the flow (piston), while centrifugal compressors, by design, must receive a continuous minimum flow (to avoid a zone called the pump zone, which poses a risk of mechanical failure).

[0031] However, the inventors observed that this combination of compression stages in this order enables particularly energy-efficient compression.

[0032] In detail, the arrangement of the turbo compressor 22 downstream of the reciprocating compressor 21 allows the turbo compressor 22 to achieve its theoretical maximum energy efficiency by achieving a lower specific speed than known solutions. The supply of the centrifugal compressor 22 with a relatively high pressure flow (provided by the reciprocating compressor 21) allows for optimal efficiency as a result of the reduced volumetric flow rate at the suction inlet of the centrifugal compressor 22. This advantage is significant because even if this configuration were not assumed, a relatively large residual axial force can be generated between the turbine wheel on one side and the compressor wheel on the other side of the shaft.

[0033] As shown, upstream of the final expansion turbine 24, the cycle gas flow can be divided into a first flow that supplies the final turbine 24 before returning to the intermediate stage of compression, and a second flow that supplies, for example, a Joule-Thomson valve 25 before returning to the inlet of compression.

[0034] As schematically shown in Figure 2, each piston compressor may include a structure with a piston 121 that can move within a chamber for compressing cycle gas, and a piston actuator 7 (with a motor). A system 210 for drawing cycle gas into the compression chamber and a system 211 for delivering the compressed cycle gas from the compression chamber are provided, for example, via a suitable shutter or valve. Members 8 for controlling the suction system 210 and the delivery system 211 are provided for controlling the displacement and / or compression ratio of the positive displacement and reciprocating compression stage 21. The control members 8 include, for example, an electronic control unit having a microprocessor.

[0035] For example, the control member 8 can control various types of operation. For example, in the first operation, the suction shut-off member must not remain open, or allow 0%, 25%, 50%, 75%, or 100% of the flow to be processed to flow in.

[0036] In a second possible operation, the suction and delivery closure members are opened and closed to allow the desired flow to pass through the piston.

[0037] In a third possible operation, the compression chamber can be activated to alter the flow processed by the piston by expanding its volume.

[0038] Similarly, the refrigerator 2 may have systems 14, 15 for regulating at least one of the expansion turbines 24, and for diverting fluid flow supplied to the turbines 24, including throttle valves 13 at the inlets of the expansion turbines. This regulation system can be configured to maintain the expansion rate determined at the end of each turbine 24.

[0039] As shown in Figure 2, the freezer 2 may include a downstream centrifugal compression regulating system configured to regulate the series-arranged centrifugal compression stages 22. This regulating system may include systems 9, 10 for diverting the fluid flow supplied to all or part of the centrifugal compression stages 22, a variable frequency device 17, and at least one inlet flow regulator 11 ("IGV") for the gas flow supplied to the centrifugal compression stages 22.

[0040] This downstream compression control system may be configured to control the flow rate of the cycle gas in the centrifugal compression stage 22 and reduce the flow rate of the cycle gas in the centrifugal compression stage 22 in response to a reduction in the flow rate of the cycle gas that can be accommodated in the turbine 24, for example.

[0041] As shown in Figure 2, the bypass system may have one or more bypass conduits 9 and a set of bypass valves 10.

[0042] For example, a first bypass conduit 9 equipped with valve 10 can bypass all of the centrifugal compression stages 22 arranged in series. A second bypass conduit 9 equipped with valve 10 can bypass at least multiple centrifugal compressors 22 arranged in series downstream of the first centrifugal compressor 22. A third bypass conduit 9 equipped with valve 10 can bypass a single centrifugal compressor 22, for example, a compressor at the downstream end of a series arrangement. All or some of these bypass conduits 9 can be combined as needed, for example, when starting up the equipment.

[0043] As shown in the variation in Figure 3, each bypass conduit 9 with a valve 10 may be provided to each compressor 22 (and, where appropriate, associated cooler 23). This allows for the selective bypassing of one or more series-arranged compressors 23 and / or the regeneration of gas around the compressors to improve the energy efficiency of the freezer 2.

[0044] As schematically shown, the cycle circuit 12 preferably includes a volume 16 for damping compression pulsations, arranged between positive displacement and reciprocating compression stages 21 and a centrifugal compression stage 22. This damping volume 16 is sized to reduce the pressure amplitude of the cycle gas between the outlet of one or more positive displacement and reciprocating compression stages 21 and the inlet of the centrifugal compression stage 22 to one-tenth to one-hundredth. In the example shown, this damping volume includes, for example, a pressurized buffer storage device. Naturally, this volume can be generated by equivalent dimensional settings of the circuit between these two compression sections (the conduit of the circuit and a possible coolant exchanger 23 downstream of the reciprocating compressor 21). This damping volume may include one or more internal elements that facilitate pulsation reduction, such as tubes containing chicanes and / or holes.

[0045] As shown in Figure 1, this freezer 2 can be used within a device 1 for liquefying a supply fluid such as hydrogen and / or helium. Such a device 1 (also called a liquefaction unit or liquefaction apparatus) includes a supply circuit 3 having an upstream end intended to connect to a source 2 of a supply gas (e.g., H2) and a downstream end 23 intended to connect to a member 4 (e.g., at least one cryogenic storage device) for collecting the liquefied supply gas.

[0046] Equipment 1 includes a set of heat exchangers 5 that exchange heat with the supply circuit 3 and are cooled by the freezer 2 mentioned above.

[0047] As shown, the apparatus 1 may also have at least one pre-cooling system 6 that exchanges heat with at least a portion of a set of heat exchangers 5. This pre-cooling system 6 includes a refrigerator with a circuit 25 of a heat transfer fluid, such as liquid nitrogen, and / or a cycle circuit of a mixture of coolants, such as nitrogen and a plurality of hydrocarbons. This pre-cooling system 6 may be configured to pre-cool the supply gas from an initial temperature (e.g., ambient temperature) at the upstream end to an intermediate temperature (e.g., 80-100K). The refrigerator 2 then cools the supply gas from the intermediate temperature to a liquefaction temperature.

[0048] The flow of the supply gas can be changed (particularly with respect to the flow rate). This constitutes a heat load to be cooled, which fluctuates. This preferably requires a variable cooling force for the freezer. This variable heat load can be measured or determined by measuring or calculating, for example, the flow rate of the supply gas in supply circuit 3 (or any other representative parameter) and / or a determined change in the temperature at the cooling end of the freezer cycle circuit (specifically, the temperature drop at the cooling end without changing the freezer setpoint, indicating that the flow rate being cooled tends to decrease, thus indicating a smaller heat load).

[0049] For example, in response to a signal representing a decrease in the thermal load of circuit 3 for the supply fluid, member 8 for controlling the suction system 210 and delivery system 211 of the reciprocating positive displacement compressor may be configured to reduce the pressure and / or mass flow rate at the outlet of this positive displacement and reciprocating compressor. This decrease in pressure and / or volumetric flow rate can therefore be achieved by modifying the displacement and / or compressibility of one or more compression stages 21 of the positive displacement and reciprocating compressor.

[0050] Therefore, the apparatus can liquefy hydrogen by first compressing the cycle gas using positive displacement and reciprocating motion, then compressing the cycle gas using centrifugal motion, centrifugally expanding the cycle gas compressed using centrifugal motion, and recovering part of the centrifugally expanding operation for centrifugal compression.

[0051] The control member 8, and / or the system for adjusting the pressure of the centrifugal compressor, and / or the system for adjusting the turbine, can maintain a given production capacity in the liquefaction unit. These adjustment devices (valves 10 for bypassing each compressor or group of compressors, throttle valves (13) at the inlet of the cryogenic turbine, valves for bypassing the turbine or regenerative gas at the inlet of the reciprocating cycle compressor, and / or the system 8 for controlling and commanding suction, and / or the delivery closure members of one or more reciprocating compressors) can adapt the refrigeration force to the thermal load.

[0052] Centrifugal compressors and / or turbines can be mounted on static and / or dynamic gases or magnetic bearings. The bearing gas can be returned to the compression system and compressed.

[0053] The turbo compressor can operate in brake mode. This means that the compressor 22 does not receive the gas flow to be compressed (e.g., via a bypass), but instead forms a passive brake for the turbine 24 connected to it.

[0054] In this operating mode, the centrifugal turbine 24 remains connected to the centrifugal compressor 22, but the supply to the centrifugal compressor is separated from the rest of the cycle circuit 12 by an element that interrupts the fluid flow, such as a valve or a removed piping element. The fluid circulating through the centrifugal compressor has the same properties as the fluid circulating through the centrifugal turbine 24. The fluid circulates within a closed loop centered on the centrifugal compressor and undergoes the following modifications in particular: compression within the centrifugal compressor, cooling within the exchanger, and pressure reduction within expansion elements such as valves. In this operating mode, the bypass 9 can continue the circuit 12 between the piston compressor 21 and the centrifugal turbine 24 without passing through the centrifugal compressor 22 operating in brake mode. Some of the turbo compressors 22 in the circuit 12 can operate in compression mode ("booster"), and some can operate in brake mode. All possible combinations of brake mode and booster mode for various turbo compressors 22 can be considered. The transition from brake mode to compression mode, and from compression mode to brake mode, of one or more turbo compressors 22 can be performed in either an operating or stopped freezer 2.

[0055] A unit for purifying cycle gases by adsorption can also be installed between the centrifugal compressor and the turbine expansion chamber.

Claims

1. A freezer comprising a cycle for refrigerating a cycle gas mainly containing hydrogen and / or helium, wherein the freezer has a cycle circuit (12) including a mechanism (21, 22) for compressing the cycle gas, at least one member (23, 5) for cooling the cycle gas, a mechanism (24, 25) for expanding the cycle gas, and at least one member (5) for heating the expanded cycle gas, wherein the compression mechanism includes at least one positive displacement and reciprocating compression stage (21) and at least two centrifugal compression stages (22) arranged in series, and the expansion mechanism includes at least two centripetal expansion turbines (2 4) A freezer comprising, wherein at least one of the turbines (24) is mechanically coupled (122) to a centrifugal compression stage (22) so as to provide the compression stage (22) with the mechanical work generated during the expansion, and the at least one positive displacement and reciprocating compression stage (21) is arranged in series upstream of the at least two centrifugal compression stages (22), wherein the freezer has a system for regulating at least one of the expansion turbines (24) and including a throttle valve (13) at the inlet of the expansion turbine, and / or a system (14, 15) for diverting the fluid flow supplied to the turbine (24).

2. The freezer according to claim 1, wherein the system for regulating the at least one expansion turbine (24) is configured to maintain the expansion rate determined at the end of the turbine (24).

3. The freezer according to claim 1 or 2, wherein the freezer includes a downstream compression regulating system configured to regulate the at least two centrifugal compression stages (22) arranged in series, the downstream compression regulating system comprising a system (9, 10) for diverting the fluid flow supplied to all or part of the centrifugal compression stages (22), a frequency variable device (17) associated with at least one of the centrifugal compression stages (22), and at least one inlet flow regulator (11) ("IGV") for the gas flow supplied to at least one of the centrifugal compression stages (22).

4. The refrigerator according to claim 3, characterized in that the downstream compression control system is configured to control the flow rate of the cycle gas in the centrifugal compression stage (22), and for example, to reduce the flow rate of the cycle gas in the centrifugal compression stage (22) in response to a reduction in the flow rate of the cycle gas that can be contained in the turbine (24).

5. The freezer according to any one of claims 1 to 4, characterized in that the compression mechanism has at least three centrifugal compression stages (22) arranged in series.

6. The refrigerator according to any one of claims 1 to 5, characterized in that the expansion mechanism includes at least two turbines (24), each mechanically connected (122) to each centrifugal compression stage (22).

7. The freezer according to any one of claims 1 to 6, characterized in that the compression mechanism has at least two positive displacement and reciprocating compression stages (21) arranged in series.

8. The refrigerator according to any one of claims 1 to 7, characterized in that the expansion mechanism includes at least one Joule-Thomson type expansion valve (25) arranged in series downstream of at least one of the two expansion turbines (24).

9. The freezer according to any one of claims 1 to 8, characterized in that the positive displacement and reciprocating compression stage (21) includes a piston compressor.

10. The freezer according to claim 9, wherein the piston compressor includes a piston (121) that can move within a chamber for compressing the cycle gas, an actuator (7) for the piston, a system (210) for drawing in the cycle gas to be compressed into the compression chamber, a system (211) for delivering the compressed cycle gas from the compression chamber, and a member (8) for controlling the drawing system (210) and / or the delivery system (211) to control the mass flow rate and / or the compression ratio of the positive displacement and reciprocating compression stage (21).

11. The freezer according to claim 9 or 10, characterized in that the control member (8) controls the opening and closing of the volume expansion portion of the compression chamber, and the expansion portion can be activated to modify the mass flow rate that the piston compressor must compress.

12. The freezer according to any one of claims 1 to 11, wherein the cycle circuit (12) includes a volume (16), such as a pressurized buffer storage device, arranged between the positive displacement and reciprocating compression stage (21) and the centrifugal compression stage (22) for attenuating the pressure pulsations, and the attenuation volume (16) is sized to reduce the pressure amplitude of the cycle gas between the outlet of the one or more positive displacement and reciprocating compression stages (21) and the inlet of the centrifugal compression stage (22) to one-tenth to one-hundredth.

13. The freezer according to any one of claims 1 to 12, characterized in that the cycle circuit (12) does not have a member for cooling the cycle gas at at least one of the outlets of the centrifugal compression stages (22) other than the last centrifugal compression stage (22).

14. Apparatus for liquefying a supply fluid such as hydrogen and / or helium, comprising a circuit (3) for a supply fluid having an upstream end intended to be connected to a supply gas source (2) and a downstream end (23) intended to be connected to a member (4) for collecting the liquefied supply gas, wherein the apparatus (1) comprises a set of heat exchangers (5) that exchange heat with the circuit (3) for the supply fluid, and the apparatus (1) comprises at least one freezer (2) that exchange heat with at least a portion of the set of heat exchangers (5), the freezer (2) being the apparatus according to any one of claims 1 to 13.

15. The liquefaction apparatus according to claim 14, wherein the freezer (2) is the liquefaction apparatus according to claim 10, and the member (8) for controlling the suction system (210) and the delivery system (211) in response to a signal representing the decrease in the heat load of the circuit (3) for the supply fluid is configured to reduce the pressure and / or the mass flow rate at the outlet of the positive displacement and reciprocating compression stage (21) by modifying the mass flow rate and / or the compressibility of the positive displacement and reciprocating compression stage (21), and the signal representing the decrease in the heat load of the circuit (3) for the supply fluid is supplied, for example, by a member for determining the flow rate and / or the characteristics of the supply gas flow of the apparatus and / or a measured value of a determined modification at the temperature of the cold end of the cycle circuit (12) of the freezer for the same operation and / or a measured value of a determined modification at the temperature of the circuit for the supply fluid, for example, downstream of the set of heat exchangers and upstream of the expansion, for the same operation.

16. A method for liquefying a supply fluid, such as hydrogen, using a liquefaction apparatus according to claim 15 or 16, the method comprising the steps of first compressing the cycle gas in a positive displacement and reciprocating manner, then compressing the cycle gas in a centrifugal manner, centrifugally expanding the centrifugalally compressed cycle gas, and recovering part of the centrifugally expanding operation for the centrifugal compression.

17. The method according to claim 16, characterized in that the method involves the steps of adjusting the mass flow rate of the cycle gas compressed by the positive displacement and reciprocating compression as a function of the heat load of the supply gas flow, and adjusting the flow rate of the cycle gas in the centripetal expansion and centrifugal compression as a function of the mass flow rate of the cycle gas compressed by the positive displacement and reciprocating compression.

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