Fluid compression device and filling station
By connecting the central guide to the fixed structure via a support piece in the piston's opening, the complexity and wear issues of cryogenic pumps are addressed, resulting in a simpler, more durable, and reliable fluid compression device with enhanced part alignment and reduced maintenance.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-07-18
- Publication Date
- 2026-03-27
AI Technical Summary
Known cryogenic pump architectures are complex, require a large number of parts, and can lead to premature part wear due to the complex arrangement of moving and fixed parts, particularly involving a plate traversed by shafts to transmit forces.
The central guide is connected to the fixed structure via a support piece received in a longitudinal opening of the piston, allowing the piston to slide relative to the support piece, simplifying the assembly and ensuring good alignment of parts, thus improving the service life of wear parts and facilitating assembly.
This arrangement simplifies assembly, ensures reliable operation with fewer parts, enhances part alignment, and increases the durability of seals and gaskets, leading to improved wear resistance and reduced maintenance.
Smart Images
Figure 00000016_0000 
Figure 00000017_0000 
Figure 00000018_0000
Abstract
Description
Title of the invention: Fluid compression apparatus and filling station
[0001] The invention relates to a fluid compression device and a filling station.
[0002] The invention relates more particularly to a fluid compression device, in particular for cryogenic fluid, comprising a compression chamber, an intake system communicating with the compression chamber, a piston comprising an axial body movable in translation along a longitudinal direction to ensure the compression of the fluid in the compression chamber, the piston being movable relative to a fixed structure of the device, the device comprising an evacuation orifice communicating with the compression chamber and configured to allow the outlet of compressed fluid, the body of the piston comprising a tubular portion mounted around a fixed central guide connected to the fixed structure, the device comprising a sealing system formed between the central guide and the tubular portion of the piston, the compression chamber being delimited by the tubular portion of the piston and a terminal end of the central guide.
[0003] Known cryogenic pump architectures are relatively complex and / or require a relatively large number of parts and / or can generate premature part wear.
[0004] In particular, the relative arrangement of the moving (piston) and fixed (fixed structure) parts requires complex assemblies. Known solutions use a plate that forms a support for the piston. The plate is traversed one or more times by shafts in order to transmit the forces from the actuator (motor, generally in the upper part) to the cylinder liner or the piston (generally in the lower part).
[0005] Document FR3107573A1 describes an example of a prior art pumping device.
[0006] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.
[0007] To this end, the device according to the invention, which also conforms to the generic definition given in the preamble above, is essentially characterized in that the central guide is connected to the fixed structure via a support piece received in a longitudinal opening formed in the body of the piston and allowing the relative longitudinal sliding of the piston around the support piece.
[0008] This arrangement is relatively simple and ensures very good alignment of the parts. This improves the service life of wear parts (seals, gaskets, seals). scrapers, guide rings).
[0009] This arrangement allows for a simple, reliable, reproducible assembly of all the parts.
[0010] Furthermore, embodiments of the invention may include one or more of the following features: - During the translational movements of the piston, the piston body slides around the support piece without passing through the support piece. - the longitudinal opening of the piston is delimited by a portion of the piston body in the shape of a multi-pronged fork, the longitudinal opening being formed by the spacing between the prongs, - the support piece extends transversely to the longitudinal direction between two lateral ends projecting beyond the piston body, the two lateral ends of the support piece each being connected to the structure, - the central guide is mounted securely to the support piece by at least one of the following: screwing, interlocking, elastic deformation, the support piece being made secure to the fixed structure, for example by stop, interlocking, clamping or screwing, - the support piece is held fixed longitudinally within the structure between two longitudinal retaining stops located on either side of the support piece along a longitudinal direction, - The structure comprises two tubular housing sections assembled longitudinally around the piston, - at least one of the two tubular housing portions forms a longitudinal retaining stop at one longitudinal end of the support piece, - the device includes a spacer mounted around the piston body, the spacer being positioned between the piston body and at least one of the two tubular housing portions, the spacer forming a longitudinal retaining stop at one longitudinal end of the support piece, - the support piece is held fixed transversely to the longitudinal direction by a transverse retaining stop formed by the structure, - the discharge port is located at the terminal end of the central guide, the device comprising a compressed fluid discharge circuit including a first end connected to the discharge port and a second end located opposite the first end in the longitudinal direction, the compressed gas discharge circuit passing through the body of the central guide and the support piece, - The piston body is composed of several parts assembled longitudinally to one another in a removable manner, The tubular portion and the fork-shaped portion of the piston body are assembled longitudinally to each other in a removable manner, for example by screwing. The device is of the two-stage compression type and includes a pre-compression chamber, a pre-admission system communicating with the pre-compression chamber configured to allow fluid entry into the pre-compression chamber, the admission system communicating with the pre-compression chamber to ensure the transfer of compressed fluid from the pre-compression chamber to the compression chamber for further compression, The device comprises a sealed enclosure connected to the structure and configured to contain a cryogenic fluid bath comprising a liquid phase and a gaseous space, the compression chamber being housed within the enclosure to be immersed in the bath, depending on the longitudinal direction of piston translation, the pre-admission system is located at a first end of the device, preferably lower, the discharge orifice being located at a second end of the device, preferably upper, the pre-admission system includes one or more openings ensuring or not communication between the pre-compression chamber and the bath to the outside depending on the longitudinal position of the piston, The port(s) are arranged to allow, when the piston passes them (i.e., when the piston is located beyond at least part of the port(s)), communication between the pre-compression chamber and the external bath; during the intake phase, when the volume of the pre-compression chamber increases, the port(s) are configured to allow any gas present in the pre-compression chamber to escape through the port(s) into the external bath and be replaced by liquid; during the compression phase (i.e., when the piston decreases the volume of the pre-compression chamber), the port(s) are configured to allow excess liquid to escape and to meter the volume of liquid trapped in the pre-compression chamber to a predetermined value before no longer communicating with the first pre-compression chamber; the intake system includes at least one of the following: one or more check valves,at least one flat disc valve or valve(s) configured to ensure the entry of fluid to be compressed into the compression chamber (pre-compression chamber) during an intake phase and to prevent fluid exit during the compression phase.
[0011] The invention also relates to a filling station for tanks or pressurized gas lines comprising a source of liquefied gas, in particular liquefied hydrogen, a withdrawal circuit having a first end connected to the source and at least a second end intended to be connected to a tank to be filled, the withdrawal circuit comprising a pumping apparatus or a fluid compression apparatus conforming to any one of the characteristics above or below.
[0012] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.
[0013] Other features and advantages will become apparent from the following description, given with reference to the figures in which: Brief description of the figures
[0014] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:
[0015] [Fig-1] is a schematic and partial vertical cross-sectional view, and according to a first Cross-sectional drawing of a fluid compression device according to a first embodiment,
[0016] [Fig.2] is a schematic and partial vertical cross-sectional view, and according to a second cross-sectional plane perpendicular to the first cross-sectional plane, of the fluid compression apparatus of [Fig.1],
[0017] [Fig.3] is a schematic and partial perspective view of the fluid compression apparatus of [Fig.1] in its disassembled configuration,
[0018] [Fig.4] is a schematic and partial vertical cross-sectional view, and according to a first plane of section, of a detail of the partially disassembled fluid compression apparatus,
[0019] [Fig.5] is a schematic and partial vertical cross-sectional view, and a second cross-sectional view of a detail of the partially disassembled fluid compression apparatus,
[0020] [Fig.6] is a schematic and partial vertical cross-sectional view, along a first plane of section, of a fluid compression device according to a second embodiment,
[0021] [Fig.7] is a schematic and partial view of an example of a tank filling station. Detailed description
[0022] In all figures, the same references refer to the same elements.
[0023] In this detailed description, the following achievements are examples. The fact that the description refers to one or more embodiments does not mean that the features apply only to a single embodiment. Simple features from different embodiments can also be combined and / or interchanged to provide other embodiments.
[0024] The fluid compression apparatus 1 illustrated in [Fig. 6] is an example of a single-stage compression embodiment. This compression apparatus 1 is, for example, a pump for pumping a cryogenic fluid, for example, liquid hydrogen, preferably at high pressure (typically several hundred bar).
[0025] The compression device 1 comprises a compression chamber 4, an intake system 6 communicating with the compression chamber 4 and a piston 5 comprising an axial body movable in translation along a longitudinal direction A, one end of which ensures the compression of the fluid in the compression chamber 4.
[0026] The device 1 has a fixed structure 24, 25 which carries most of the fixed and moving parts, and in particular a sealed enclosure 13 connected to the structure 24, 25 and configured to contain a bath 16 of cryogenic fluid comprising a liquid phase and a gaseous space. The compression chamber 4 is housed within the enclosure 13 so as to be immersed in the bath 16.
[0027] As illustrated, the structure may comprise two tubular housing portions 24, 25 (or sleeves) assembled longitudinally to each other hermetically around the piston 5, for example by screwing.
[0028] The piston 5 is free to move in translation within the structure along the longitudinal direction A in a reciprocating motion. The piston 5 is, for example, moved by means of an actuator 21 (a motor possibly associated with a motion transformation system). The actuator 21 is preferably located at the top of the device 1, for example mounted on the structure.
[0029] Any type of actuator 21 can be considered: a linear actuator, for example a hydraulic cylinder, an electromechanical cylinder, a ball screw, a roller screw or a crank-type motion conversion system itself driven by a geared motor, a motor and a belt or a direct drive motor.
[0030] The compression device 1 includes a discharge port 7 communicating with the compression chamber 4 and configured to allow the outlet of compressed fluid. The piston body 5 includes a tubular portion 15 mounted around a fixed central guide 8. The central guide 8, for example cylindrical, is connected to the structure 24, 25.
[0031] A sealing system 10 is provided between the central guide 8 and the tubular portion 15 of the piston 5. This sealing system includes a set of seal(s), for example a set of O-rings, and can be associated with one or more guide rings of the tubular portion 15 relative to the central guide.
[0032] The compression chamber 4 is thus delimited by the tubular portion 15 of the piston 5 and a terminal end of the central guide 8.
[0033] As illustrated, the entire compression chamber 4 can be contained within the tubular portion of the piston 5.
[0034] As illustrated, in the operating position, the piston 5 is preferably vertical, the intake system 6, the discharge port 7, the compressed fluid outlet and the actuator are placed in that order from bottom to top.
[0035] The discharge port 7 is preferably located at the lower end of the central guide 8. The device 1 includes a compressed fluid discharge circuit 11 comprising a first end connected to the discharge port 7 and a second end located opposite the first end of the device 1. This compressed gas discharge circuit 11 preferably passes through the interior of the body of the central guide 8 and through a support piece 9 via suitable channels.
[0036] In this non-limiting embodiment example, the compression of the fluid in the compression chamber 4 is obtained by a rising of the piston 5 (traction force).
[0037] As schematically shown, the central guide 8 is connected to the fixed structure 24, 25 via a support piece 9 received in a longitudinal opening 25 formed in the body of a piston 5, 15 and allowing the relative longitudinal sliding of the piston 5 around the support piece 9.
[0038] During the translational movements of the piston 5, the body of the piston 5 slides around the support part 9, preferably without passing through the support part 9.
[0039] This is also illustrated in [Fig. 1], [Fig. 2], and [Fig. 3], which illustrate another two-stage compression embodiment. The embodiment of [Fig. 1], [Fig. 2], and [Fig. 3] differs from that of [Fig. 6] only in that it is of the two-stage compression type. The same elements are designated by the same reference numerals and are not described in detail a second time. The two-stage compression embodiment comprises a pre-compression chamber 3 and a pre-admission system 2 communicating with the pre-compression chamber 3, configured to allow fluid to enter from the bath 16 into the pre-compression chamber 3.
[0040] In this configuration, the pre-compression chamber 3 is delimited at its lower end, for example, by a lower flange 12 (or obturator) which transversely closes the tubular portion at its lower end. This flange 12 may include the pre-admission system 2 (appropriate valve(s)). This lower flange 12 may also include an overflow valve configured to limit the pressure rise in the pre-compression chamber 3. This lower flange 12 may optionally be used for centering the cold end (assembly mechanical parts assembled here) relative to enclosure 13. This can be provided to ensure alignment between enclosure 13 and the cold end of the pre-compression chamber via a retaining device for the cold end relative to enclosure 13 (and to limit possible vibrations).
[0041] The compression chamber 4 intake system 6 communicates with the pre-compression chamber 3 to ensure the transfer of compressed fluid in the pre-compression chamber 3 (first compression stage) to the compression chamber 4 for further compression (second compression stage).
[0042] The first compression stage is obtained in this example by a downward stroke of the piston 5 (piston compression) while the second compression stage is obtained by an upward stroke of the piston 5 (upward pull) and so on.
[0043] Thus, the lower end of the piston 5 forms a mobile fluid compression surface in the pre-compression chamber 3 while the tubular portion of the piston 5 forms a mobile sleeve which cooperates with the terminal end of the central guide 8 to form a fluid compression system in the compression chamber 4 in which the terminal end of the central guide 8 forms a fixed piston.
[0044] Thus, preferably, the longitudinal direction A of translation of the piston 5 is vertical, the pre-admission system 2 being located at a first lower end of the device 1, the evacuation port 7 being located at a second upper end of the device 1.
[0045] Preferably, the fluid pre-admission system in the pre-compression chamber includes one or more lights or slots formed in the upper part of the wall delimiting the pre-compression chamber (lights not shown for the sake of simplification) ensuring or not a communication between the pre-compression chamber 3 and bath 16 to the outside depending on the longitudinal position of the piston 5.
[0046] The port(s) can be arranged longitudinally to allow communication between the pre-compression chamber 3 and the external bath 16 when the piston 5 passes over them, i.e., when the piston 5 is located beyond at least part of the port(s). During the intake phase, when the volume of the pre-compression chamber 3 increases, the port(s) are configured to allow any gas present in the pre-compression chamber 3 to escape through the port(s) into the external bath 16 and be replaced by liquid. During the compression phase, i.e., when the piston 5 decreases the volume of the pre-compression chamber 3, the port(s) are configured to allow excess liquid to escape and to meter the volume of liquid trapped in the pre-compression chamber 3. compression to a predetermined value before no longer communicating with the first pre-compression chamber 3.
[0047] The pre-admission system 2 and the admission system 6 may include at least one of: one or more check valves, at least one flat disc valve or valve(s) configured to ensure the entry of fluid to be compressed into the chamber concerned (compression / pre-compression) during an admission phase and prevent the exit of fluid during the compression phase.
[0048] As can be seen in particular in [Fig.2], the longitudinal opening 50 of the piston 5 which receives the support piece 9 can be delimited by a portion of the body of the piston 5 in the shape of a two-branched fork 125. The longitudinal opening 50 can thus be formed by the spacing between the parallel branches 125.
[0049] The support part 9 can thus extend transversely to the longitudinal direction A between two lateral ends projecting beyond the body of the piston 5. The two lateral ends of the support part 9 can be connected or fixed each to the structure 24, 25, on either side of the body of the piston 5.
[0050] The support part 9 can be held fixed longitudinally within the structure 24, 25 between two longitudinal retaining stops 123, 124 located on either side of the support part 9 along a longitudinal direction A. For example, two tubular sections 24, 25 (or sleeves) are joined longitudinally around the piston 5. This optimizes the transmission of force between the parts 8, 9, 24, 25.
[0051] One of the tubular housing portions (for example the lower portion 24) can form a longitudinal retaining stop 124 which receives a longitudinal end of the support part 9 (for example the lower end).
[0052] As illustrated, a spacer 23, for example tubular, can be mounted around the piston body 5, between the piston body 5 and one of the two tubular housing portions 24, 25 (for example, in the lower tubular portion 24). The upper end of the spacer 23 abuts, for example, against a shoulder formed by the upper tubular portion 25. The lower end of the spacer 23 rests, for example, on the upper portion of the support piece 9. Thus, the support piece 9 is longitudinally locked by the structure 24, 25 between the spacer 23 and the lower tubular portion 24.
[0053] The spacer 23 is thus housed above the support piece 9 and can retain the latter and also provides the counter-force to keep the central guide 8 fixed.
[0054] The force is thus transmitted to the upper portion 25 of the housing. This spacer 23 also ensures centering between the upper portion 25 of the housing and the lower portion 24 of the housing.
[0055] In the illustrated example, the spacer 23 has the shape of a tube. Of course, this in tretoise can have other geometry, for example the general shape of a ring, for example interposed between the support piece and one or the other of the portions 23, 24 of the case.
[0056] Similarly, the spacer 23 could be omitted. In this case, the longitudinal locking of the upper support part 9 could be ensured, for example, by a portion 24 of the tubular housing.
[0057] The support part 9 is blocked transversely to the longitudinal direction A for example by a portion 24 of tubular housing of the structure which surrounds it.
[0058] The support part 9 can thus be made integral with the fixed stop structure 24, 25, but it is also possible to consider interlocking, clamping or screwing, for example.
[0059] As described in more detail below, the central guide 8 can be mounted securely to the support part 9 by at least one of the following: screwing, fitting, elastic deformation.
[0060] As illustrated in [Fig.3] and [Fig.4] and [Fig.5], the body of the piston 5 can be composed of several parts assembled longitudinally to each other in a detachable manner, for example by screwing.
[0061] For example, the lower tubular portion 15 and the upper fork-shaped portion of the piston body 5 are longitudinally joined to each other in a detachable manner, for example by screwing. Similarly, the junction between the fork-shaped portion and the upper solid portion can be assembled in a separable manner.
[0062] Such an architecture requires relatively few parts and ensures reliable operation while allowing easy assembly and disassembly.
[0063] An example of the assembly of the main components will now be described with reference to [Fig.3].
[0064] In a first step, the support piece 9 can be inserted transversely into the longitudinal opening 50 of the piston 5.
[0065] This support piece 9 can be mounted with sliding plates on its outer surface (copper plate with PTFE coating for example) and with sufficient clearance relative to the longitudinal opening 50 to ensure relative sliding between the two pieces 125 and 9.
[0066] The architecture allows for good alignment of the parts along the longitudinal direction which ensures and guarantees good sealing and good durability of the joints 10.
[0067] The support piece 9 is preferably also mounted with a clearance in the lower portion 24 of the housing to ensure optimal alignment between the two longitudinal ends of the piston 5 during assembly.
[0068] The upper end of the central guide 8 can be secured to the part 9, by example by screwing, through a passage (bore for example) formed at the lower end of the fork-shaped portion of the piston 5. The tubular portion 15 forming the lower end of the piston can then be mounted around the central guide 8 and fixed to the upper fork-shaped portion of the piston 5.
[0069] Of course, the two upper and lower portions of the piston can be fixed in different ways and at different longitudinal levels. For example, the two parts of the piston 5 can be separable at the lower part of the tubular portion 15 (jacket), for example, by means of a screwed-on end. Similarly, the piston 5 can be made of a single piece. Likewise, the piston 5 can be made of more than two parts assembled in a separable manner. For example, the upper end can be made of several separable parts, and in particular of three parts.
[0070] This assembly with the support piece 9 can be housed in the lower portion of the tubular housing 24 of the structure. The spacer 23 can then be mounted around the piston 5.
[0071] The resulting assembly can then be fitted onto the upper tubular housing portion 25 of the structure. The upper end of the piston 5 is inserted into the upper tubular housing portion 25 (upper part of the structure). The two parts 24, 25 of the structure can be joined together, for example by screwing, at two ends having, for example, assembly flanges.
[0072] Alternatively, the spacer 23 could be mounted above the support piece 9, and then the upper end of the piston 5 could be inserted into the upper portion 25 of the housing structure. The lower portion 24 of the housing can then be assembled to the upper portion 25 of the housing.
[0073] Alternatively, the assembly does not include a spacer 23.
[0074] The piston 5 is preferably guided longitudinally in its upper part within the upper portion 25 of the housing, which forms a sleeve. This guidance can be provided by one or more guide rings interposed in contact with the piston 5. The guide rings can be made of a material with a low coefficient of friction (for example, PTFE and bronze or PTFE and carbon).
[0075] The piston 5 can also be guided longitudinally around the tubular portion 15 in the lower portion 24 of the housing (also with one or more rings if necessary).
[0076] A set of seal(s) (for example, piston rings) carried by the lower part of the tubular portion of the piston can ensure sealing with the lower portion 24 of the housing. This set of seal(s) can also contribute to longitudinal guidance.
[0077] The support piece 9 may include an outlet 105 for the pressurized fluid coming from the compression chamber 4 and which has passed through the central guide 8, the orifice 7 evacuation and through the body of the support part 9. A conduit of the evacuation circuit 11 can be provided to this fluid outlet 105 to collect and transport the compressed fluid to an outlet of the compression device 1.
[0078] As shown in [Fig. 2], the lower portion 24 of the housing may have a lateral opening to allow the passage of this pipe 11, and in particular its connection end to the support piece 9. This connection of the pipe to the fluid outlet 105 may be achieved, for example, via a threaded fitting which may be used with a seal, for example, of a metallic and reinforced type. Of course, any other type of high-pressure fluid fitting, such as a "conical" or "NPT" type, or other, may be considered.
[0079] The upper portion 25 of the housing is fixed and can be rigidly connected to, or form part of, the enclosure 13 containing the cryogenic fluid bath to be pumped. In particular, this upper portion of the fixed structure can include or constitute an upper mounting flange for the enclosure 13.
[0080] The actuator 21 of the piston 5 (motor and associated mechanism, if applicable) can be mounted on this upper portion 25 of the structure. The actuator 21 can be mechanically coupled to the upper end of the piston 5 to actuate the latter in translation and transmit the forces necessary for the different phases of fluid intake and compression.
[0081] The main mechanical force generated by the piston 5 (fork-shaped portion and tubular portion delimiting the compression chamber) during compression in the compression chamber 4 (traction) is absorbed at the end of the piston forming the compression chamber. This force is transmitted to the support part 9, then to the spacer 23, and to the upper portion 25 of the structure.
[0082] The above arrangement and its resulting assembly / disassembly allow for guidance and alignment of the mechanism parts.
[0083] The number of parts is limited, assembly / disassembly is simple.
[0084] The transfer of forces (particularly in tension) is optimized. This contributes to a increased lifespan of the various seals.
[0085] Of course, the invention is not limited to the examples described above. Thus, for example, the spacer 23 could be part (monobloc or not) of the upper housing portion 25.
[0086] Similarly, the support piece 9 and at least part of the central guide 8 could be one piece provided that the resulting piece can be inserted through the longitudinal opening 50.
[0087] A compression device 1 of this type (or several in series or parallel) can be used in any cryogenic installation requiring the pumping or compression of a cryogenic fluid. For example, a gas tank filling station under The pressure (hydrogen, for example) system may include a liquefied gas source 17, a withdrawal circuit 18 having a first end connected to the source and at least one second end intended to be connected to a tank 190 to be filled, the withdrawal circuit 18 including such a pumping apparatus 1. The pumped fluid may be vaporized in a downstream heat exchanger 19 and optionally stored in one or more pressurized buffer tanks 20.
Claims
Demands
1. Apparatus (1) for compressing fluid, in particular cryogenic fluid, comprising a compression chamber (4), an inlet system (6) communicating with the compression chamber (4), a piston (5, 15) comprising an axial body movable in translation along a longitudinal direction (A) to ensure the compression of the fluid in the compression chamber (4), the piston (5) being movable relative to a fixed structure (24, 25) of the apparatus (1), the apparatus (1) comprising an outlet (7) communicating with the compression chamber (4) and configured to permit the discharge of compressed fluid, the body of the piston (5) comprising a tubular portion (15) mounted around a fixed central guide (8) connected to the fixed structure (24, 25), the apparatus (1) comprising a sealing system (10) formed between the central guide (8) and the tubular portion (15) of the piston (5),the compression chamber (4) being delimited by the tubular portion (15) of the piston (5) and a terminal end of the central guide (8), the central guide (8) being connected to the fixed structure (24, 25) via a support piece (9) received in a longitudinal opening (50) formed in the body of the piston (5, 15) and allowing the relative longitudinal sliding of the piston (5) around the support piece (9), characterized in that, during the translational movements of the piston (5), the body of the piston (5) slides around the support piece (9) without passing through the support piece (9).
2. Apparatus (1) according to claim 1, characterized in that the longitudinal opening (50) of the piston (5, 15) is delimited by a portion of the piston body (5) in the form of a multi-branched fork (125), the longitudinal opening (50) being formed by the spacing between the branches (125).
3. Apparatus (1) according to any one of claims 1 to 2, characterized in that the support piece (9) extends transversely in the longitudinal direction (A) between two lateral ends projecting beyond the body of the piston (5), the two lateral ends of the support piece (9) being connected each to the structure (24, 25).
4. Apparatus (1) according to any one of claims 1 to 3, characterized in that the central guide (8) is mounted integrally with the support part (9) by at least one of the following: screwing, fitting, elastic deformation, the support part (9) being made integral with the fixed structure (24, 25), for example by stop, fitting, clamping or screwing.
5. Apparatus (1) according to any one of claims 1 to 4, characterized in that the support part (9) is held fixed longitudinally in the structure (24, 25) between two longitudinal retaining stops (123, 124) located on either side of the support part (9) in a longitudinal direction (A).
6. Apparatus (1) according to any one of claims 1 to 5, characterized in that the structure comprises two tubular housing portions (24, 25) assembled longitudinally to each other around the piston (5).
7. Device (1) according to claims 5 and 6, characterized in that at least one of the two tubular housing portions (24, 25) forms a longitudinal retaining stop at one longitudinal end of the support part (9).
8. Apparatus (1) according to claim 6 or 7, characterized in that it comprises a spacer (23) mounted around the body of the piston (5), the spacer (23) being disposed between the body of the piston (5) and at least one of the two tubular housing portions (24, 25), the spacer (23) forming a longitudinal retaining stop at one longitudinal end of the support piece (9).
9. Apparatus (1) according to any one of claims 1 to 8, characterized in that the support part (9) is held fixed transversely to the longitudinal direction (A) by a transverse retaining stop (24) formed by the structure (24, 25).
10. Apparatus (1) according to any one of claims 1 to 9, characterized in that the discharge orifice (7) is located at the terminal end of the central guide (8), the apparatus (1) comprising a compressed fluid discharge circuit (11) comprising a first end connected to the discharge orifice (7) and a second end located opposite to the first end in the longitudinal direction (A), the compressed gas discharge circuit (11) passing through the body of the central guide (8) and the support piece (9).
11. Apparatus (1) according to any one of claims 1 to 10, characterized in that the piston body (5) is composed of several parts assembled longitudinally to each other in a detachable manner.
12. Apparatus (1) according to claims 2 and 11, characterized in that the tubular portion (15) and the fork-shaped portion of the piston body (5) are assembled longitudinally to each other in a dis- can be mounted, for example by screwing.
13. Apparatus (1) according to any one of claims 1 to 12, characterized in that it is of the two-stage compression type and comprises a pre-compression chamber (3), a pre-admission system (2) communicating with the pre-compression chamber (3) configured to permit the entry of fluid into the pre-compression chamber (3), the admission system (6) communicating with the pre-compression chamber (3) to ensure the transfer of compressed fluid in the pre-compression chamber (3) to the compression chamber (4) for further compression.
14. Apparatus (1) according to any one of claims 1 to 13, characterized in that it comprises a sealed enclosure (13) connected to the structure (24, 25) and configured to contain a bath (16) of cryogenic fluid comprising a liquid phase and a gaseous space, the compression chamber (4) being housed in the enclosure (13) to be immersed in the bath (16).
15. A filling station for tanks or pressurized gas lines comprising a source (17) of liquefied gas, in particular liquefied hydrogen, a withdrawal circuit (18) having a first end connected to the source and at least a second end intended to be connected to a tank (190) to be filled, the withdrawal circuit (18) comprising a pumping apparatus (1) or a fluid compression apparatus (1) according to any one of claims 1 to 14.