Fluid compression device and filling station

Abstract

The invention relates to a cryogenic fluid compression apparatus (1) comprising a compression chamber (4), an inlet system (6), a piston (5, 15) movable in translation along a longitudinal direction (A) in the compression chamber (4) relative to a fixed structure (24, 25) of the apparatus (1), an outlet (7) communicating with the compression chamber (4) and configured to allow the outlet of compressed fluid, 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 structure (24,25) fixed 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). The invention also relates to a filling station comprising such an apparatus. Abbreviated figure: Fig. 1,

Description

Title of the invention: Fluid compression apparatus and filling station

[0001] The invention relates to a fluid compression apparatus and a filling station.

[0002] The invention relates more particularly to an apparatus for compressing fluid, in particular cryogenic fluid, comprising a compression chamber, an intake system communicating with the compression chamber, a piston comprising an axial body movable in translation in 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 apparatus, the apparatus 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 apparatus 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 wear of parts.

[0004] In particular, the relative arrangement of the moving (piston) and fixed (fixed structure) parts requires complex assemblies. Known solutions use a plate forming a support for the piston. The plate is crossed one or more times by axes in order to transmit the forces from the actuator (motor generally in the upper part) to the sleeve or the piston (generally in the lower part).

[0005] Document FR3107573A1 describes an example of a pumping device of the prior art.

[0006] An aim of the present invention is to overcome all or part of the drawbacks 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 the wear parts (seals, gaskets scrapers, guide rings).

[0009] This arrangement allows for simple, reliable, reproducible assembly of all the parts.

[0010] Furthermore, embodiments of the invention may include one or more of the following features: - during translational movements of the piston, the body of the piston slides around the support part without passing through the support part, - the longitudinal opening of the piston is delimited by a portion of the piston body in the form of a fork with several branches, the longitudinal opening being formed by the spacing between the branches, - the support piece extends transversely to the longitudinal direction between two lateral ends projecting beyond the body of the piston, the two lateral ends of the support piece each being connected to the structure, - the central guide is mounted integral with the support part by at least one of: screwing, fitting, elastic deformation, the support part being made integral with the fixed structure, for example by stop, fitting, 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 apparatus is of the two-stage compression type and comprises a pre-compression chamber, a pre-intake system communicating with the pre-compression chamber configured to allow the entry of fluid into the pre-compression chamber, the inlet system communicating with the pre-compression chamber to ensure the transfer of compressed fluid in 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, according to the longitudinal direction of translation of the piston, 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 comprises one or more ports ensuring or not communication between the pre-compression chamber and the bath to the outside according to 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 prevent the exit of fluid during the compression phase.

[0011] The invention also relates to a station for filling pressurized gas tanks or pipes comprising a source of liquefied gas, in particular liquefied hydrogen, a withdrawal circuit having a first end connected to the source and at least one 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 appear on reading the description below, given with reference to the figures in which: Brief description of the figures

[0014] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0015] [Fig-1] is a schematic and partial vertical sectional view, and according to a first sectional plan of a fluid compression device according to a first embodiment,

[0016] [Fig.2] is a schematic and partial vertical sectional view, and along a second sectional plane perpendicular to the first sectional plane, of the fluid compression apparatus of [Fig.l],

[0017] [Fig.3] is a schematic and partial perspective view of the fluid compression apparatus of [Fig.l] in the disassembled configuration,

[0018] [Fig.4] is a schematic and partial vertical sectional view, and according to a first sectional plane, of a detail of the partially dismantled fluid compression apparatus,

[0019] [Fig.5] is a schematic and partial vertical sectional view, and according to a second sectional plane of a detail of the partially dismantled fluid compression apparatus,

[0020] [Fig.6] is a schematic and partial vertical sectional view, and along a first sectional plane, of a fluid compression apparatus 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 the figures, the same references refer to the same elements.

[0023] In this detailed description, the following embodiments are examples. Well that the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0024] The fluid compression apparatus 1 illustrated in [Fig. 6] is an example of an embodiment with a single compression stage. 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 bars).

[0025] The compression apparatus 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 in a longitudinal direction A, one end of which ensures the compression of the fluid in the compression chamber 4.

[0026] The apparatus 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 atmosphere. The compression chamber 4 is housed in the enclosure 13 to be immersed in the bath 16.

[0027] As illustrated, the structure may comprise two portions 24, 25 of tubular housing (or sleeves) assembled longitudinally to each other hermetically around the piston 5, for example by screwing.

[0028] The piston 5 is movable in translation in the structure in the longitudinal direction A in an alternating movement. The piston 5 is for example moved via an actuator 21 (motor possibly associated with a movement transformation system). The actuator 21 is preferably located in the upper part of the device 1, for example mounted on the structure.

[0029] Any type of actuator 21 can be envisaged: a linear actuator, for example a hydraulic cylinder, an electromechanical cylinder, a ball screw, a roller screw or by a motion conversion system of the crank rod type itself driven by a geared motor, a motor and a belt or even a direct drive motor.

[0030] The compression apparatus 1 comprises an evacuation orifice 7 communicating with the compression chamber 4 and configured to allow the exit of compressed fluid. The body of the piston 5 comprises 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 comprises a set of seal(s), for example a set of O-rings, and may be associated with one or more rings for guiding 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 position of use, the piston 5 is preferably vertical, the intake system 6, the discharge orifice 7, the compressed fluid outlet and the actuator are placed in this order from bottom to top.

[0035] The discharge orifice 7 is preferably located at the lower terminal end of the central guide 8. The apparatus 1 comprises a circuit 11 for discharging the compressed fluid comprising a first end connected to the discharge orifice 7 and a second end located opposite the first end of the apparatus 1. This circuit 11 for discharging the compressed gas preferably passes through the interior of the body of the central guide 8 and through a support part 9 via appropriate channels.

[0036] In this non-limiting example embodiment, the compression of the fluid in the compression chamber 4 is obtained by a rise of the piston 5 (traction force).

[0037] As shown schematically, the central guide 8 is connected to the fixed structure 24, 25 via a support part 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 part 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 the enclosure 13. This may be provided to ensure alignment between the enclosure 13 and the cold end of the pre-compression chamber via a member for holding the cold end relative to the enclosure 13 (and to limit possible vibrations).

[0041] The intake system 6 of the compression chamber 4 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 additional compression (second compression stage).

[0042] The first compression stage is obtained in this example by a downward stroke of the piston 5 (compression of the piston) while the second compression stage is obtained by an upward stroke of the piston 5 (traction rise) and so on.

[0043] Thus, the lower end of the piston 5 forms a mobile surface for compressing the fluid in the pre-compression chamber 3 while the tubular portion of the piston 5 forms a mobile jacket which cooperates with the terminal end of the central guide 8 to form a system for compressing the fluid 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 orifice 7 being located at a second upper end of the device 1.

[0045] Preferably, the fluid pre-admission system into the pre-compression chamber comprises one or more openings or slots formed in the upper part of the wall delimiting the pre-compression chamber (openings not shown for the sake of simplification) ensuring or not communication between the pre-compression chamber 3 and the 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 part 9 can be delimited by a portion of the body of the piston 5 in the form of a fork with two branches 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 in the structure 24, 25 between two longitudinal holding stops 123, 124 located on either side of the support part 9 in a longitudinal direction A. For example, two tubular portions 24, 25 (or sleeves) are assembled to each other longitudinally around the piston 5. Thus the transmission of the force between the parts 8, 9, 24, 25 is optimized.

[0051] One of the tubular housing portions (for example the lower portion 24) may form a longitudinal holding 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 part 9 and can retain the latter and furthermore 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 makes it possible to ensure centering between the upper housing portion 25 and the lower housing portion 24.

[0055] In the example illustrated, the spacer 23 has the shape of a tube. Of course, this The brace may have other geometry, for example the general shape of a ring, for example interposed between the support part and one or other of the portions 23, 24 of the housing.

[0056] Similarly, the spacer 23 could be omitted. In this case, the longitudinal locking of the support part 9 in the upper part 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 envisage interlocking, tightening or screwing for example.

[0059] As described in more detail below, the central guide 8 can be mounted integral with the support part 9 by at least one of: screwing, fitting, elastic deformation.

[0060] As illustrated in [Fig.3] and in [Fig.4] and [Fig.5], the body of the piston 5 can be composed of several parts assembled longitudinally to each other in a removable 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 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 part 9 can be mounted with sliding plates on its outer surface (copper plate with PTFE coating for example) and with sufficient play relative to the longitudinal opening 50 to ensure relative sliding between the two parts 125 and 9.

[0066] The architecture allows good alignment of the parts in the longitudinal direction which ensures and guarantees good sealing and good durability of the joints 10.

[0067] The support part 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 a different longitudinal level. For example, the two parts of the piston 5 can be separable in the lower part of the tubular portion 15 (liner), for example via a screwed bottom. Similarly, the piston 5 can be composed of a single piece. Likewise, the piston 5 can be composed of more than two pieces assembled in a separable manner. For example, the upper end can be composed of several separable parts and in particular in 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 assembly obtained can then be topped with 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 assembled to each other, for example by screwing, at two ends comprising 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 the upper part in the upper portion 25 of the housing which forms a sheath. 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 housing portion 24 (also with one or more rings if necessary).

[0076] A set of seal(s) (for example segments) 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 discharge and through the body of the support part 9. A conduit of the discharge circuit 11 can be connected to this fluid outlet 105 to collect and transport the compressed fluid to an outlet of the compression apparatus 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 may be rigidly connected to or form part of the enclosure 13 containing the bath of cryogenic fluid to be pumped. In particular, this upper portion of the fixed structure may comprise 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 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 admission and compression of the fluid.

[0081] The main mechanical force which is generated by the piston 5 (fork-shaped portion and tubular portion delimiting the compression chamber) during compression in the compression chamber 4 (traction) is taken up 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 structural portion 25.

[0082] The above arrangement and its resulting assembly / disassembly allow guidance and alignment of the mechanism parts.

[0083] The number of parts is limited, assembly / disassembly is simple.

[0084] The recovery of forces (particularly in traction) 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 (in one piece 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 in 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 in parallel) can be used in any cryogenic installation requiring pumping or compressing a cryogenic fluid. For example, a gas tank filling station under pressure (hydrogen for example) may comprise a source 17 of liquefied gas, 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 comprising such a pumping apparatus 1. The pumped fluid may be vaporized in a downstream exchanger 19 and possibly stored in one or more buffer tanks 20 under pressure.

Claims

Claims

1. Apparatus (1) for compressing fluid, in particular cryogenic fluid, comprising a compression chamber (4), an intake system (6) communicating with the compression chamber (4), a piston (5, 15) comprising an axial body movable in translation in 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 evacuation orifice (7) communicating with the compression chamber (4) and configured to allow the outlet 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), characterized in that the central guide (8) is connected to the fixed structure (24, 25) via a support part (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 part (9).,

2. Apparatus (1) according to claim 1, characterized in that, during translational movements of the piston (5), the body of the piston (5) slides around the support part (9) without passing through the support part (9).

3. Apparatus (1) according to claim 1 or 2, characterized in that the longitudinal opening (50) of the piston (5, 15) is delimited by a portion of the body of the piston (5) in the form of a fork with several branches (125), the longitudinal opening (50) being formed by the spacing between the branches (125).

4. Apparatus (1) according to any one of claims 1 to 3, characterized in that the support part (9) extends 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) each being connected to the structure (24, 25).

5. Apparatus (1) according to any one of claims 1 to 4, characterized in that the central guide (8) is mounted integral with the support part (9) by at least one of: screwing, fitting, deformation elastic, the support part (9) being made integral with the fixed structure (24, 25), for example by stop, interlocking, clamping or screwing.

6. Apparatus (1) according to any one of claims 1 to 5, characterized in that the support part (9) is held fixed longitudinally in the structure (24, 25) between two longitudinal holding stops (123, 124) located on either side of the support part (9) in a longitudinal direction (A).

7. Apparatus (1) according to any one of claims 1 to 6, characterized in that the structure comprises two portions (24, 25) of tubular housing assembled longitudinally to each other around the piston (5).

8. Apparatus (1) according to claims 6 and 7, characterized in that at least one of the two tubular housing portions (24, 25) forms a longitudinal holding stop at a longitudinal end of the support part (9).

9. Apparatus (1) according to claim 7 or 8, characterized in that it comprises a spacer (23) mounted around the body of the piston (5), the spacer (23) being arranged between the body of the piston (5) and at least one of the two portions (24, 25) of tubular housing, the spacer (23) forming a longitudinal holding stop at a longitudinal end of the support part (9).

10. Apparatus (1) according to any one of claims 1 to 9, characterized in that the support part (9) is held fixed transversely to the longitudinal direction (A) by a transverse holding stop (24) formed by the structure (24, 25).

11. Apparatus (1) according to any one of claims 1 to 10, characterized in that the discharge orifice (7) is located at the terminal end of the central guide (8), the apparatus (1) comprising a circuit (11) for discharging the compressed fluid comprising a first end connected to the discharge orifice (7) and a second end located opposite the first end in the longitudinal direction (A), the circuit (11) for discharging the compressed gas passing via the body of the central guide (8) and the support part (9).

12. Apparatus (1) according to any one of claims 1 to 11, characterized in that the body of the piston (5) is composed of several parts assembled longitudinally to each other in a removable manner.

13. Apparatus (1) according to claims 3 and 12, 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 removable manner, for example by screwing.

14. Apparatus (1) according to any one of claims 1 to 13, 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 allow 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.

15. Apparatus (1) according to any one of claims 1 to 14, 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 atmosphere, the compression chamber (4) being housed in the enclosure (13) to be immersed in the bath (16).

16. Station for filling tanks or pressurized gas pipes 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 one 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 15.

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