COMPRESSION DEVICE AND FILLING STATION WITH SUCH A DEVICE

Description

[0001] The invention relates to a compression apparatus and a filling station comprising such an apparatus. Such an apparatus is, for example, a cryogenic pump, particularly for pumping liquefied hydrogen.

[0002] The invention relates more particularly to a cryogenic fluid compression apparatus comprising a sealed enclosure for containing a cryogenic fluid bath, a compression chamber communicating with the bath, an inlet system communicating with the compression chamber configured to allow the entry of fluid to be compressed into the compression chamber, a movable piston for compressing the fluid in the compression chamber, the apparatus further comprising an outlet system communicating with the compression chamber and configured to allow the outlet of compressed fluid, the piston being mounted at a first end of a rod, the apparatus comprising a mechanism for driving the rod in a back-and-forth motion in a longitudinal direction,The drive mechanism comprises a motor equipped with a rotating shaft and a mechanical system converting the rotational movement of the rotating shaft into a translational movement of a head sliding along the longitudinal direction and to which a second end of the rod is connected.

[0003] Crank-and-connecting-rod drive is a well-known actuation solution for cryogenic piston pumps. Most of these pumps operate with oil splash lubrication to guide the piston rod. This architecture is well-suited to horizontal piston rod configurations because oil leakage is very limited. The piston rod can be guided by plain bearings or anti-friction strips (e.g., bronze plates).

[0004] For a vertically configured cryogenic pump, splash lubrication of the motion conversion mechanism is very difficult. This is because the cold end of the pump is placed in a sump (usually called a sump), and the articulated mechanism must be positioned vertically on top of it. Oil leaks occur along the piston rod due to the linear reciprocating motion. For safety reasons, oil droplets falling onto the cryogenic section are not permitted.

[0005] One solution is to use a leak collection and recirculation system (with pump, filter, etc.). This solution is not satisfactory.

[0006] One solution is to use an oil-free linear guide mechanism (e.g., roller carriages, ball bushings, etc.) mounted on the side receiving the generated transverse force. This design is subject to significant stresses that limit its lifespan and require frequent maintenance. Furthermore, this solution can cause a high temperature increase, necessitating system shutdowns. In addition, the piston stroke is relatively short compared to the load (forces). The size of the sliding head is close to the stroke length. Moreover, the forces are poorly distributed due to the asymmetry of the mechanism. To absorb the forces, multiple sliding heads can be used, or several guides can be employed on the load-bearing side with additional mechanical couplings (ball joints for mounting). However, this does not completely resolve the problems.

[0007] US patent 3,251,602 A discloses an apparatus for pumping highly volatile liquefied gases; DE patent 102 22 313 C1 discloses a motor having deformable elastic rails to guide a sliding element.

[0008] One aim of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0009] To this end, the compression device according to the invention, which also conforms to the generic definition given in the preamble above, is essentially characterized in that the head is mounted to slide and guided by two fixed guide rails located on either side of the head and in that the head and / or a rail includes an elastic portion, said elastic portion being configured to generate on the rail(s) a force transverse to the longitudinal direction, and in that the elastic portion includes a spring or a deformable zone and is prestressed.

[0010] Furthermore, embodiments may include one or more of the following characteristics: The compression of the fluid in the compression chamber is achieved by a pull or compression of the rod, said pull or compression generating a transverse thrust of the head on one of the rails in a direction transverse to the longitudinal direction, the force generated by the elastic portion being in the opposite direction to this thrust, the elastic portion is configured to generate on the rail(s) a transverse force having, in absolute value, an intensity less than, equal to, or greater than the maximum intensity of the thrust force, the elastic portion is located between a central zone of the head and one of the two rails, the elastic portion is located between one of the two rails and the fixed support of said rail, the elastic portion includes a spring or a deformable zone and is prestressed, in the operating configuration, the rod is mobile in a reciprocating motion in a vertical longitudinal direction,The mechanical system converting the rotational movement of the rotating shaft into a translational movement of the carriage is of the connecting rod and crank type; the mechanical system converting the rotational movement of the rotating shaft into a translational movement of the head is connected to a central area of ​​the head via a ball joint or pivot joint, said joint being located on a longitudinal line passing through the axis of translation of the rod, said line also being intersecting the line passing through the rotating shaft of the motor; the head is mounted to slide in the guide rails via a guide system with or without rolling element(s), for example a roller system, and / or ball bearings and / or slide rollers or a precision rail system; the device is of the single-stage compression type, i.e., the fluid is compressed only once between the inlet system and the outlet system.The device is of the two-stage compression type, meaning that the fluid is compressed twice between the inlet and outlet systems. The device comprises two compression chambers: the inlet system communicates with the first compression chamber, and a transfer system communicates with both the first and second compression chambers and is configured to allow the transfer of compressed fluid from the first compression chamber to the second. The moving piston alternately compresses the fluid in the first and second compression chambers according to its direction of movement. The outlet system communicates with the second compression chamber. The second compression chamber is delimited by a portion of the piston body and a fixed wall of the device.

[0011] The invention also relates to a filling station according to claim 13.

[0012] Other features and advantages will become apparent upon reading the description below, which refers to the figures in which: [ Fig.1 ] represents a schematic and partial vertical cross-sectional view, illustrating an example of the structure and operation of a compression device according to the invention, [ Fig.2 ] represents a schematic and partial horizontal cross-sectional view of a detail of the aforementioned device at the level of the arrangement of one end of a sliding head and its vertical guide rail, [ Fig.3 ] represents another schematic and partial horizontal cross-sectional view of a detail of the aforementioned device at the level of the arrangement of one end of the sliding head and its vertical guide rail, illustrating rolling elements, [ Fig.4 ] schematically and partially represents an example of force distribution at one end of the sliding head and its guide rail of the device in a traction configuration, [ Fig.5 ] represents a schematic and partial cross-sectional view, illustrating a detail of a possible embodiment of the compression chamber of such a compression device, [ Fig.6 ] represents a schematic and partial cross-sectional view, illustrating a detail of a second possible embodiment of the compression chamber of such a compression device, [ Fig.7 ] represents a schematic and partial cross-section, illustrating a detail of a third possible embodiment of the compression chamber of such a compression device, [ Fig.8 ] represents a schematic and partial view illustrating a detail of the device illustrating an example of a possible realization of the structure of the elastic portion, [ Fig.9 ] represents a schematic and partial view, illustrating an example of a filling station using such a compression device.

[0013] The cryogenic fluid compression apparatus 1, shown schematically, comprises a sealed enclosure 13 for containing a cryogenic fluid bath 16 (typically a liquid phase in the lower part and a gaseous phase in the upper part). The apparatus 1 has at least one compression chamber 3 communicating with the liquid bath (in particular, the compression chamber 3 is preferably immersed in the bath).

[0014] Device 1 includes an inlet system 2 communicating with the compression chamber 3 and configured to allow the entry of fluid to be compressed into the compression chamber 3 (typically including a system of valve(s) and / or orifice(s)).

[0015] The apparatus 1 further includes a movable piston 5 to ensure the compression of the fluid in the compression chamber 3 and an evacuation system 7 communicating with the compression chamber 3 configured to allow the outlet of compressed fluid (typically including a set of valve(s) and communicating with an evacuation line).

[0016] The piston 5 is mounted at one end of a rod 50. The apparatus 1 includes a drive mechanism 21 for driving the rod 50 in a reciprocating motion along a longitudinal direction A. The drive mechanism 21 conventionally comprises a motor 121 with a rotating shaft 211 and a mechanical system 212, 213 that converts the rotational motion of the rotating shaft 211 into a translational motion of a sliding head 8 along the longitudinal direction A. A second end of the rod 50 is connected to the head to receive its actuating force.

[0017] The 8-head can be composed of one or more assembled pieces. This 8-head can also be referred to in the literature as a "crossbar", "cross" or "cross-shaped head" ("Crosshead" in English).

[0018] For example, the piston rod 50 can be connected to one end of the head 8 via a coupling piece, such as a rigid connection (e.g. bolted flange type) or a flexible one (e.g. ball joint or pivot type).

[0019] The head 8 is mounted to slide and guided by two fixed guide rails 9. The two rails 9 are located on either side of the head 8 (on either side in a direction perpendicular to the longitudinal direction A). The head 8 is guided in translation by the rails 9 and receives the tensile and thrust forces via one end of the mechanism 21; for example, a connecting rod 213 is connected to the head 8 at a ball joint or pivot joint 11.

[0020] As illustrated, the mechanical system converting the rotational movement of the rotating shaft 211 into a translational movement of the head 8 can be connected to a central area of ​​the head 8 via a link 11 located on a longitudinal line A passing through the axis of translation of the rod 50. In addition, this line can also be intersecting the line passing through the rotating shaft 211 of the motor 210.

[0021] As illustrated in cross-section at [ Fig.2] et [Fig.3 ], each end of the head 8 can be slidably mounted on a rail 9. As can be seen in the [ Fig.3 The head 8 can be slidably mounted on the guide rail 9 via a set 12 of rollers and / or balls. The sliding system can also be of the precision rail type or any other suitable guiding system (preferably not using oil in the case where the axis of the rod is vertical in the operating position).

[0022] For example, carriages (roller or ball bearing) are screwed onto the head 8 and move with it. The rails 9, for example, are fixed to the frame of the device. For lubrication, a passive (or active) cartridge can nevertheless be mounted on each of the carriages.

[0023] The head 8 includes an elastic portion 10 which is configured to generate on the rail or rails 9 a transverse force in the longitudinal direction A.

[0024] That is to say, the elastic portion 10 generates a permanent transverse force on the rail(s) 9.

[0025] The compression movement of the fluid in the compression chamber 3 generates significant forces in the mechanism (the fluid compression is obtained when the rod is pulled on the representation of the [ Fig.1 Due to the asymmetrical mechanism (eccentric type), during this compression, the lateral forces at the rails 9 are not symmetrical. In particular, one rail 9 may be more transversely loaded than the other (the left rail in this non-limiting example shown).

[0026] The aforementioned arrangement allows for at least partial rebalancing of these transverse forces in apparatus 1.

[0027] Indeed, as schematically shown in the [ Fig.4 The force Fm exerted by the motion transformation mechanism 21 induces a tensile component Ft on the rod 50 and a transverse thrust component F1 towards one of the rails 9. The elastic portion 10 is configured to generate a continuous force F2 on this same rail 9, in the opposite direction to this thrust F1, and which at least partially compensates for it (for example, the force F2 is sized to reduce the thrust force F1 by half). Note that a force F2 can also be generated on the other rail 9; this has no particular influence on the proper functioning of the device.

[0028] Note that the intensity of this force F2 generated by the elastic portion is preferably constant, while the thrust F1 has an intensity that varies cyclically during the movements. The value of F2 can be chosen to partially compensate for the maximum intensity of F1 during the cycle.

[0029] The maximum thrust force (when operating under low load, the spring force will be greater than the thrust force).

[0030] This means that the elastic portion 10 constantly exerts a "transverse compensating load." The resulting final force in the mechanism is thus limited, reducing stress during the most stressful operating phase. This results in better balancing or damping of the transverse forces.

[0031] Thus, instead of using a guide rail threshold on one side of the head 8 (on the side receiving the forces), this solution provides a second guide rail which, with the elastic element 10, reduces the lateral forces.

[0032] Note that this arrangement also allows for addressing alignment and potential spacing issues between the two rails 9 to ensure proper assembly (assembly tolerances). As shown schematically, the elastic portion 10 can be located between the central area of ​​the head 8 and one of the two rails 9. This elastic portion 10 can include a spring or a pre-stressed deformable area or any other component generating an appropriate force. As schematically illustrated in [ Fig.8 ], this elastic portion may include a spring formed by a loop-shaped portion (for example, two-lobed) of a part of the body of the head 8.

[0033] Note that the elastic portion 10 can be integrated into (or constituted by) the head 8. Elements 8 and 10 can be separate parts or the same part.

[0034] In the example of the [ Fig.1 ] as well as in the example of the [ Fig.6 ], the fluid compression effort is obtained by pulling (up) the rod 50.

[0035] Of course, this is by no means exhaustive. Thus, and as illustrated in the [ Fig.5 The fluid compression force can be obtained by pushing (descent) the rod 50. In this case, the lateral forces are reversed compared to the description above. In this case, the force F2 of the elastic portion 10 can also simply be reversed (either by moving this elastic portion to the other side of the head or by modifying the structure of the elastic portion 10 so that its force is oriented to oppose the excessive force on the side concerned).

[0036] Note that in the implementation method of the [ Fig.6 The piston 5 comprises a tubular portion mounted around a fixed central guide 15. One end of the central guide 15 forms the fixed wall delimiting a portion of the compression chamber 3 from the tubular portion of the piston 5.

[0037] In the aforementioned examples, device 1 is of the single-stage compression type (fluid compressed only once). Of course, the invention also applies in the same way to a two-stage compression device (fluid undergoing two compressions in series). The [ Fig.7Figure 1 illustrates an example of a two-stage compression structure. The device 1 may include a tubular piston 5 cooperating with a tubular cavity 14 or fixed chamber, which is closed at its lower end to delimit two compression chambers 3 and 4. The inlet system 2 communicates with a first compression chamber 3. The architecture includes a transfer system 6 (valve or other) communicating with the first 3 and second 4 compression chambers and configured to allow the transfer of compressed fluid from the first 3 compression chamber to the second 4 compression chamber. The movable piston 5 alternately compresses the fluid in the first 3 (towards the second 4 chamber) and in the second 4 compression chamber, depending on its direction of movement. The outlet system 7 communicates with the second 4 compression chamber.

[0038] Device 1 can have the following operating characteristics: piston stroke between 40 and 160 mm, motor rotation speed of approximately 80 rpm to 500 rpm (corresponding to a frequency between 1.3 Hz and 8.5 Hz for piston 5). For a traction force Ft, the thrust force F1 can be on the order of 10-20% of Ft, while the opposing force generated by the elastic element 10 can be on the order of 5-10% of Ft.

[0039] The aforementioned solution offers numerous advantages.

[0040] It helps to limit the maximum load peak in the mechanism. This increases the lifespan of the guidance system subjected to these stresses.

[0041] The design eliminates the need for an oil bath lubrication system that would seep onto the cryogenic section. This design also avoids the need to manage an oil bath during maintenance operations. Only grease fittings that provide passive self-lubrication to certain components of the mechanism during operation require recharging. The solution is compact and lightweight and can be applied to any type of piston pump and any type of crank-driven mechanism.

Claims

1. A cryogenic fluid compression apparatus (1) comprising a sealed enclosure (13) intended to contain a bath (16) of cryogenic fluid, a compression chamber (3, 4) communicating with the bath, an admission system (2) communicating with the compression chamber (3, 4) configured to allow the entry of fluid to be compressed into the compression chamber (3), a mobile piston (5) to ensure the compression of the fluid in the compression chamber (3, 4), the apparatus (1) further comprising an evacuation system (7) communicating with the compression chamber (3, 4) and configured to allow the exit of compressed fluid, the piston (5) being mounted to a first end of a rod (50), the apparatus (1) comprising a mechanism (21) for driving the rod (50) in a reciprocating movement along a longitudinal direction (A), the drive mechanism (21) comprising a motor (121) provided with a rotating shaft (211) and a mechanical system (212, 213) converting the rotational movement of the rotating shaft (211) into a translational movement of a head (8) sliding along the longitudinal direction (A) and to which a second end of the rod (50) is connected, characterized in that the head (8) is slidably mounted and guided by two fixed guide rails (9) located on either side of the head (8) and in that the head (8) and / or a rail (9) comprises an elastic portion (10), said elastic portion (10) being configured to generate on the rail or rails (9) a transverse force to the longitudinal direction (A), and in that the elastic portion (10) comprises a spring or a deformable zone and is pre-stressed.

2. The apparatus according to claim 1, characterized in that the compression of the fluid in the compression chamber (3, 4) is obtained by a traction or a compression of the rod (50), said traction or compression generating a transverse thrust of the head (8) on one of the rails (9) along a direction transverse to the longitudinal direction (A), and in that the force generated by the elastic portion (10) is of opposite direction to this thrust.

3. The apparatus according to claim 2, characterized in that the elastic portion (10) is configured to generate on the rail or rails (9) a transverse force having, in absolute value, an intensity less than or equal to the maximum intensity of the thrust force.

4. The apparatus according to any one of claims 1 to 3, characterized in that the elastic portion (10) is located between a central zone of the head (8) and one of the two rails (9).

5. The apparatus according to any one of claims 1 to 4, characterized in that the elastic portion (10) is located between one of the two rails (9) and a fixed support of said rail.

6. The apparatus according to any one of claims 1 to 5, characterized in that, in operating configuration, the rod (50) is mobile in a reciprocating movement along a vertical longitudinal direction (A).

7. The apparatus according to any one of claims 1 to 6, characterized in that the mechanical system (212, 213) converting the rotational movement of the rotating shaft (211) into a translational movement of the head (8) is of the connecting rod (213) and crank (212) type.

8. The apparatus according to any one of claims 1 to 7, characterized in that the mechanical system (212, 213) converting the rotational movement of the rotating shaft (211) into a translational movement of the head (8) is connected to a central zone of the head (8) via a ball-and-socket or pivot joint (11), said joint (11) being located on a longitudinal straight line (A) passing through the axis of translation of the rod (50), said straight line also being secant to the straight line passing through the rotating shaft (211) of the motor (210).

9. The apparatus according to any one of claims 1 to 8, characterized in that the head (8) is slidably mounted in the guide rails (9) via a guide system with or without rolling element(s), for example a roller system, and / or balls and / or sliding blocks or a precision rail(s) type system.

10. The apparatus according to any one of claims 1 to 9, characterized in that it is of the single-stage compression type, that is to say that the fluid is compressed only once between the admission system (2) and the evacuation system (7).

11. The apparatus according to any one of claims 1 to 10, characterized in that it is of the two-stage compression type, that is to say that the fluid is compressed twice between the admission system (2) and the evacuation system (7), the apparatus (1) comprising two compression chambers (3, 4), the admission system (2) communicating with a first compression chamber (3), a transfer system (6) communicating with the first (3) and the second (4) compression chamber and configured to allow the transfer of compressed fluid from the first compression chamber (3) to the second compression chamber (4), the mobile piston (5) alternately ensuring the compression of the fluid in the first (3) and second (4) compression chambers according to its direction of movement, the evacuation system (7) communicating with the second compression chamber (4).

12. The apparatus according to claim 11, characterized in that the second compression chamber (4) is delimited by a portion of the piston body (5) and a fixed wall of the apparatus.

13. A filling station for tanks or gas pipes under pressure 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 compression apparatus (1) according to any one of claims 1 to 12.