Compression device and filling station including such device

Abstract

The present invention relates to a device (1) for compressing a cryogenic fluid, the device (1) comprising a sealed container (13) intended to contain a tank (16) of a cryogenic fluid, compression chambers (3, 4) in communication with the tank, an intake system (2) in communication with the compression chambers (3, 4) and configured to allow the fluid to be compressed to enter the compression chambers (3), and a movable piston (5) for compressing the fluid in the compression chambers (3, 4), the device (1) further comprising an exhaust system (7) in communication with the compression chambers (3, 4) and configured to allow the compressed fluid to leave, the piston (5) being mounted on a first end of a rod (50) and the device (1) being arranged such that the rod (50) is movable in a longitudinal direction (A) such that the rod (50) is reciprocatingly movable. the head (8) being mounted and guided for sliding by two fixed guide rails (9) arranged on either side of the head (8); and the head (8) and / or one of the rails (9) including an elastic portion (10) configured to generate a force on one or both of the rails (9) perpendicular to the longitudinal direction (A).

Description

[Technical field]

[0001] The present invention relates to a compression device and a filling station including such a device, for example a cryogenic pump, in particular a cryogenic pump for pumping liquid hydrogen.

[0002] The invention particularly relates to an apparatus for compressing a cryogenic fluid, the apparatus comprising a sealed container intended to contain a tank of cryogenic fluid, a compression chamber in communication with the tank, an intake system in communication with the compression chamber and configured to allow the fluid to be compressed to enter the compression chamber, and a movable piston for ensuring compression of the fluid in the compression chamber, the apparatus further comprising an exhaust system in communication with the compression chamber and configured to allow the compressed fluid to leave, the piston being mounted on a first end of a rod, the apparatus comprising a mechanism for driving the rod so that it reciprocates in a longitudinal direction, the drive mechanism comprising a motor with a rotating shaft and a mechanical system for converting the rotational movement of the rotating shaft into a translational movement of a longitudinally sliding head, the mechanical system to which the second end of the rod is connected. [Background technology]

[0003] One of the known actuation solutions for cryogenic piston pumps is the drive by a connecting rod crank mechanism. Most of these pumps work with oil splash lubrication to guide the piston rod. This architecture is suitable for horizontal piston rod configurations, since oil leakage is very limited. The piston rod can be guided by plain bearings or anti-friction strips (e.g. bronze plates).

[0004] For vertically configured cryogenic pumps, it is very difficult to implement such splash lubrication in the motion conversion mechanism. Specifically, the cold end of the pump must be installed in a tank (commonly called a sump) and the articulation mechanism must be installed vertically above it. Oil leakage occurs along the piston rod as a result of the linear reciprocating motion. Oil drops falling on the cryogenic part are not allowed for safety reasons.

[0005] One solution is to use a system of collection and recirculation of the spill (by pumps, filters, etc.). This solution is not sufficient.

[0006] One solution is to use an oil-free linear guide mechanism (e.g. roller carriage, ball bearing sleeve, etc.) mounted on the side receiving the generated lateral force. This architecture has a limited service life and requires frequent maintenance due to the rather large forces. This solution can also cause high temperature rises that require equipment shutdown. Furthermore, the piston stroke is relatively short compared to the load (force). The sliding head size is close to the stroke size. Furthermore, the force is not well distributed due to the asymmetrical nature of the mechanism. To capture the force, multiple sliding heads may be provided on the side receiving the force, with additional mechanical connections (ball joints to allow assembly) or multiple guides may be used. However, this does not completely solve the problem. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to overcome all or some of the drawbacks of the prior art outlined above. [Means for solving the problem]

[0008] To this end, the compression device according to the invention further complies with the generic definition given in the preamble above and is essentially characterised in that the head is slidably mounted and guided by two fixed guide rails arranged on either side of the head, and that the head and / or the rails include elastic parts configured to generate a force on one or both rails perpendicular to the longitudinal direction.

[0009] Furthermore, implementations of the invention may include one or more of the following features.

[0010] Compression of the fluid in the compression chamber is achieved by pulling or compressing the rod, which generates a lateral thrust of the head on one of the rails perpendicular to the longitudinal direction, with the force generated by the elastic portion being opposite in direction to this thrust. the elastic portion is configured to generate a lateral force on one or both rails, the magnitude of the lateral force being, in absolute value, less than, equal to or greater than the maximum magnitude of the thrust force. The elastic portion is located between the central zone of the head and one of the two rails. The elastic portion is located between one of the two rails and a fixed support for that rail. The elastic portion includes a spring or a deformable zone and is pre-stressed. In the operative configuration, the rod is movable in a vertical longitudinal reciprocating motion. -The mechanical system that converts the rotational motion of the rotating shaft into the translational motion of the carriage is of the type that uses a connecting rod and a crank. - the mechanical system that converts the rotational movement of the rotating shaft into a translational movement of the head is connected to the central zone of the head by a ball joint connection or a pivot connection, which connection lies on a longitudinal line passing through the axis of translation of the rod, which line is also a secant to a line passing through the rotating shaft of the motor. The head is slidably mounted on the guide rail by a guide system with or without roller elements, for example a system with rollers and / or ball and / or sliding roller or precision rail type systems. The device is of the type with one compression stage, i.e. the fluid is compressed only once between the intake and the discharge. the device is of the type with two compression stages, i.e. the fluid is compressed twice between an intake system and a discharge system, the device comprises two compression chambers, the intake system communicates with the first compression chamber, a transmission system communicates with the first and with the second compression chamber and is configured to allow the transmission of the fluid compressed in the first compression chamber to the second compression chamber, the movable piston, in its direction of movement, alternates between compressing the fluid in the first compression chamber and compressing the fluid in the second compression chamber, and the discharge system communicates with the second compression chamber. The second compression chamber is delimited by a portion of the body of the piston and a fixed wall of the device.

[0011] The invention also relates to a station for filling tanks or pipes with compressed gas, comprising a source of liquefied gas, in particular liquid hydrogen, and a withdrawal circuit having a first end connected to the source and at least one second end intended to be connected to the tank to be filled, and including a compression device meeting any of the above or below mentioned characteristics.

[0012] The invention may also relate to any alternative device or method including any combination of the features set out above or below falling within the scope of the claims.

[0013] Further specific features and advantages will become apparent on reading the ensuing description, the description being made with reference to the drawings, in which: [Brief description of the drawings]

[0014] [Figure 1]FIG. 1 shows a schematic partial vertical cross-sectional view illustrating an example of the structure and operation of a compression device according to the invention. [Diagram 2] FIG. 2 shows a schematic partial horizontal section of a detail of the device described above, at the level of the arrangement of the sliding head and one end of its vertical guide rail. [Diagram 3] FIG. 3 shows another schematic partial horizontal section of a detail of the device described above, at the level of the arrangement of the sliding head and one end of its vertical guide rail, showing the roller members. [Figure 4] FIG. 4 shows, diagrammatically and partially, an example of the force distribution at one end of the sliding head of the device and its guide rail in the traction configuration. [Diagram 5] FIG. 5 shows a schematic partial cross-sectional view showing details of a possible variant embodiment of the compression chamber of such a compression device. [Figure 6] FIG. 6 shows a schematic partial cross-sectional view showing details of a second possible variant embodiment of the compression chamber of such a compression device. [Figure 7] FIG. 7 shows a schematic partial cross-sectional view showing details of a third possible variant embodiment of the compression chamber of such a compression device. [Figure 8] FIG. 8 shows a schematic partial view of details of the device, illustrating a possible exemplary embodiment of the structure of the elastic portion. [Figure 9] FIG. 9 shows a schematic partial view of an example of a filling station using such a compression device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The device 1 for compressing a cryogenic fluid, represented diagrammatically, comprises a sealed container 13 intended to contain a tank 16 of cryogenic fluid (the tank 16 is typically in liquid phase in its lower part and in gas phase in its upper part). The device 1 has at least one compression chamber 3 in communication with the liquid tank (in particular, the compression chamber 3 is preferably immersed in the tank).

[0016] The apparatus 1 includes an intake system 2 that is in communication with a compression chamber 3 and is configured (typically including a system of valves and / or orifices) to allow the fluid to be compressed to enter the compression chamber 3.

[0017] The device 1 further comprises a movable piston 5 which ensures compression of the fluid in the compression chamber 3, and an exhaust system 7 which is in communication with the compression chamber 3 and is configured to allow the compressed fluid to exit (typically comprising a set of valves and communicating with a drain pipe).

[0018] The piston 5 is mounted on a first end of a rod 50. The device 1 includes a mechanism 21 for driving the rod 50 such that the rod 50 moves in an alternating reciprocating manner in a longitudinal direction A. The driving mechanism 21 typically includes a motor 121 with a rotating shaft 211 and a mechanical system 212, 213, which converts the rotational movement of the rotating shaft 211 into a translational movement of a head 8 sliding in the longitudinal direction A. A second end of the rod 50 is connected to the head for receiving the movement.

[0019] The head 8 may consist of one or more assembled parts. The head 8 is sometimes referred to in the literature by the terms "cross member", "cross beam" or "cross head".

[0020] For example, the piston rod 50 may be connected to one end of the head 8 by a coupling part (eg, a rigid connection (eg, of the bolted flange type) or a flexible connection (eg, of the ball joint or pivot type)).

[0021] The head 8 is slidably mounted and guided by two fixed guide rails 9. The two rails 9 are arranged 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 traction and thrust forces through one end of a mechanism 21, for example a connecting rod 213 which is connected to the head 8 at a ball joint connection or a pivot connection 11.

[0022] As shown, the mechanical system converting the rotational movement of the rotating shaft 211 into a translational movement of the head 8 may be connected to the central zone of the head 8 via a connection 11 lying on a longitudinal line A passing through the axis of translation of the rod 50. Moreover, this line may also be a secant to a line passing through the rotating shaft 211 of the motor 210.

[0023] As shown in Figures 2 and the cross-sectional views of Figure 3, each end of the head 8 may be slidably mounted on a rail 9. As seen in Figure 3, the head 8 may be slidably mounted to the guide rail 9 by a set of rollers and / or balls 12. This sliding system may be of the precision rail type or any other suitable guide system (preferably no oil is used when the axis of the rod is vertical in the use position).

[0024] For example, a carriage (with rollers or balls) is screwed to the head 8 and moves with it. The rail 9 itself is for example fixed to the frame of the device. Nevertheless, a passive (or active) cartridge may be mounted on each carriage for lubrication.

[0025] The head 8 includes a resilient portion 10 configured to exert a force perpendicular to the longitudinal direction A on one or both rails 9 .

[0026] That is, the elastic portion 10 generates a permanent lateral force on the rail 9 .

[0027] The action of compressing the fluid in the compression chamber 3 generates significant forces within the mechanism (compression of the fluid occurs while the rod is being pulled in the illustration of FIG. 1). Because the mechanism is asymmetric (an eccentric mechanism), the lateral forces on the rails 9 during this compression are not symmetric. Specifically, one rail 9 may experience a larger lateral load than the other rail 9 (the left rail in this non-limiting example as shown).

[0028] The above described configuration makes it possible to rebalance these lateral forces in the device 1, at least to some extent.

[0029] Specifically, as shown diagrammatically in Fig. 4, the force Fm applied by the motion conversion mechanism 21 induces a traction component Ft on the rod 50 and a lateral 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 a direction opposite to the thrust F1, which at least partially cancels the thrust F1 (e.g., the magnitude of the force F2 is half that of the thrust F1). Note that the force F2 may also be generated on the other rail 9, but this does not particularly affect the normal operation of the device.

[0030] It should be noted that the magnitude of this force F2 generated by the elastic part is preferably constant, whereas the magnitude of the thrust force F1 varies periodically during the movement, and the value of F2 may be selected to offset to some extent the maximum magnitude of F1 during the period.

[0031] Maximum thrust (When operating at low load, the spring force is greater than the thrust.

[0032] That is to say, the elastic part 10 permanently realizes a "lateral counter-load". The final force realizing mechanism is thus limited, making it possible to limit the stresses in the phase of operation where the forces generated are at their maximum. A better balancing or clipping of the lateral forces is achieved.

[0033] Therefore, in this solution, instead of using only a guide rail on one side of the head 8 (the side receiving the force), a second guide rail is provided which, together with the elastic member 10, makes it possible to reduce the lateral forces.

[0034] However, this configuration also makes it possible to address possible alignment and spacing (assembly tolerances) issues between the two rails 9 to ensure correct assembly of the assembly. As shown diagrammatically in the figure, a resilient portion 10 may be located between the central zone of the head 8 and one of the two rails 9. This resilient portion 10 may comprise a prestressed spring, or a prestressed deformable zone, or any other suitable force generating member. As shown diagrammatically in FIG. 8, this resilient portion may comprise a spring formed by a loop-shaped portion (e.g. having two lobes) of part of the body of the head 8.

[0035] It should be noted that the elastic portion 10 may be integral with (or constituted by) the head 8. The elements 8 and 10 may be separate parts or may be an integral part.

[0036] In the example of FIG. 1, as well as in the example of FIG. 6, the force compressing the fluid is obtained by pulling (lifting) the rod 50.

[0037] Of course, this is in no way limiting. Thus, also as shown in Figure 5, the force compressing the fluid may be obtained by jerking (down) the rod 50. In this case, the lateral force is reversed from the case described above. In this case, the force F2 of the elastic part 10 may also simply be reversed (this can be done by moving this elastic part to the opposite side of the head, or by modifying the structure of the elastic part 10 so that its force is directed against the excess force on that side).

[0038] 6, the piston 5 includes a tubular portion mounted around a fixed central guide 15. The terminal end of the central guide 15 together with the tubular portion of the piston 5 forms a fixed wall that defines a portion of the compression chamber 3.

[0039] In the above example, the device 1 is of the type with one compression stage (compressing the fluid only once). Of course, the invention applies equally to compression devices with two compression stages (performing two compressions of the fluid in sequence). Figure 7 shows an example of a compression structure with two compression stages. Thus, the device 1 may include a tubular piston 5, which may be associated with a tubular cavity 14 closed at its lower end or with a fixed chamber to define two compression chambers 3, 4. The intake system 2 communicates with the first compression chamber 3. The architecture includes a transmission system 6 (valve, etc.) which communicates with the first compression chamber 3 and the second compression chamber 4 and is configured to allow the transmission of the fluid compressed in the first compression chamber 3 to the second compression chamber 4. The movable piston 5 alternates, in its direction of movement, between compressing the fluid in the first compression chamber 3 (towards the second compression chamber 4) and compressing the fluid in the second compression chamber 4. The exhaust system 7 communicates with the second compression chamber 4 .

[0040] The device 1 may have the following operating characteristics: a piston stroke of 40-160 mm and a motor rotation speed of the order of 80-500 rpm (corresponding to a piston 5 frequency of 1.3-8.5 Hz). With respect to the traction force Ft, the thrust force F1 may be of the order of 10-20% of Ft, while the opposing force generated by the elastic member 10 may be of the order of 5-10% of Ft.

[0041] The above solution has many advantages.

[0042] This solution makes it possible to limit the maximum load peaks in the mechanism, which makes it possible to extend the service life of the guide systems subjected to these forces.

[0043] This architecture eliminates the need for oil reservoir lubrication systems that would gradually leak oil onto the cryogenic parts. This architecture eliminates the need to manage the oil reservoir during maintenance operations. Only any oilers that provide passive self-lubrication in the operation of certain elements of the mechanism have to be refilled. This solution is compact, lightweight, and applicable to any type of piston pump and any type of crank drive mechanism.

Claims

1. A device (1) for compressing a cryogenic fluid, said device (1) comprising a sealed container (13) intended to contain a tank (16) of cryogenic fluid, compression chambers (3, 4) in communication with said tank, an intake system (2) in communication with said compression chambers (3, 4) and configured to allow a fluid to be compressed to enter said compression chambers (3), and a piston (5) movable to ensure compression of said fluid in said compression chambers (3, 4), said device (1) further comprising a discharge system (7) in communication with said compression chambers (3, 4) and configured to allow the compressed fluid to leave, said piston (5) being mounted on a first end of a rod (50), said device (1) comprising a mechanism (21) for driving said rod (50) so as to reciprocate in a longitudinal direction (A), The drive mechanism (21) comprises a motor (121) with a rotating shaft (211) and a mechanical system (212, 213) for converting the rotational movement of the rotating shaft (211) into a translational movement of a head (8) sliding in the longitudinal direction (A), the mechanical system (212, 213) to which the second end of the rod (50) is connected, the head (8) being slidably mounted and guided by two fixed guide rails (9) arranged on either side of the head (8), the head (8) and / or the rails (9) comprising an elastic part (10) configured to generate a force on one or both of the rails (9) perpendicular to the longitudinal direction (A), the elastic part (10) comprising a spring or a deformable zone and being pre-stressed.

2. 2. The device according to claim 1, characterized in that the compression of the fluid in the compression chambers (3, 4) is achieved by traction or compression of the rod (50), which generates a lateral thrust of the head (8) on one of the rails (9) in a direction perpendicular to the longitudinal direction (A), and that the force generated by the elastic part (10) is opposite in direction to this thrust.

3. 3. The device according to claim 2, characterized in that the elastic part (10) is configured to generate a lateral force on one or both of the rails (9), the magnitude of the lateral force being less than or equal to the maximum magnitude of the thrust force in absolute value.

4. A device according to any one of the preceding claims, characterized in that the elastic portion (10) is located between a central zone of the head (8) and either of the two rails (9).

5. A device according to any one of the preceding claims, characterized in that the elastic part (10) is located between either of the two rails (9) and a fixed support of said rail.

6. A device according to any one of claims 1 to 3, characterized in that in said operating configuration, said rod (50) is movable in a reciprocating manner in a vertical longitudinal direction (A).

7. The device according to any one of claims 1 to 3, characterized in that the mechanical system (212, 213) converting the rotational movement of the rotating shaft (211) into a translational movement of the carriage (8) is of the type using a connecting rod (213) and a crank (212).

8. The device according to any one of claims 1 to 3, 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 the central zone of the head (8) by a ball joint or pivot connection (11), said connection (11) lying on a longitudinal line (A) passing through the axis of translation of the rod (50), said line being furthermore a secant to the line passing through the rotating shaft (211) of the motor (210).

9. 4. Apparatus according to any one of claims 1 to 3, characterised in that the head (8) is slidably mounted on the guide rail (9) by a guide system with roller elements, for example a roller system and / or a ball and / or sliding roller or precision rail type system.

10. Device according to any one of claims 1 to 3, characterized in that it is of the type with one compression stage, i.e. the fluid is compressed only once between the intake system (2) and the exhaust system (7).

11. 4. The device according to claim 1, characterized in that it is of the two compression stages type, i.e. the fluid is compressed twice between the intake system (2) and the exhaust system (7), the device (1) comprises two compression chambers (3, 4), the intake system (2) communicates with the first compression chamber (3), a transmission system (6) communicates with the first compression chamber (3) and with the second compression chamber (4) and is configured to allow the transmission of the fluid compressed in the first compression chamber (3) to the second compression chamber (4), the movable piston (5) alternates in its direction of movement between compressing the fluid in the first compression chamber (3) and compressing the fluid in the second compression chamber (4), and the exhaust system (7) communicates with the second compression chamber (4).

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

13. A station for filling tanks or pipes with compressed gas, comprising a source (17) of liquefied gas, in particular liquid hydrogen, and a withdrawal circuit (18) having a first end connected to said source and at least one second end intended to be connected to a tank (190) to be filled, said withdrawal circuit (18) comprising a compression device (1) according to any one of claims 1 to 3.

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