Supercooling of the outlet fluid of a cryogenic pump

Abstract

TIRE: Supercooling of the outlet fluid of a cryogenic pump. The invention relates to a piston pump (1) for liquefied gases, such as hydrogen, said pump (1) comprising: - a supply inlet (10A) and a filling outlet (20A) - a suction chamber (2) for receiving the fluid from said inlet (10A), and - a degassing chamber (3) for the fluid communicating with a degassing outlet (20B), - a compression and discharge assembly (30) comprising a compression chamber having a compression outlet (50A) fluidically connected to the filling outlet (20A) of the piston pump (1), the compression outlet (50A) being offset from the filling outlet (20A), the compression outlet (50A) and the filling outlet (20A) being connected to each other via a connecting portion (5) running at least partially through said chamber. Degassing (3). Figure for the abbreviation: Figure 2

Description

Title of the invention: Supercooling of the outlet fluid of a cryogenic pump technical field

[0001] The invention relates to the technical field of cryogenic pumps applicable to liquefied gases at very low temperatures, such as hydrogen. STATE OF THE ART

[0002] A piston pump essentially comprises a pump cylinder with a cylinder liner and a compression chamber, a pump piston which is guided linearly in the cylinder liner, an inlet valve disposed in an inlet area of ​​the compression chamber and used for the admission of the cryogenic fluid, and an outlet valve disposed in an outlet area of ​​the compression chamber and used for the outlet of the cryogenic fluid.

[0003] The pump piston is designed to move alternately in the cylinder liner in order to perform the pumping process and to form or enlarge and reduce the compression chamber by the alternating movement of the pump piston.

[0004] More particularly, during the movement of this piston, the fluid is alternately drawn from the suction side towards the compression chamber, then pressurized to be evacuated via the dedicated outlet.

[0005] In certain filling applications, the fluid discharged through the dedicated outlet needs to be at the coldest possible temperature in order to obtain the highest possible fluid density.

[0006] However, the fluid exiting the pump can be heated primarily due to friction generated by the movement of the piston rings relative to the pump casing and due to compression. The heating generated by the movement of the piston rings can be partially mitigated by its dissipation through the fluid present in the degassing chamber, where the heated liquid can evaporate into a gas. The degassing outlet is designed to vent this gas in order to optimize the cooling of the compression and discharge assembly.

[0007] However, the degassing outlet is not sufficient to allow the outlet fluid to be cooled to the lowest possible temperature in certain filling applications.

[0008] SUBJECT OF THE INVENTION

[0009] The present invention aims to provide a solution to the technical problems described above by proposing a piston pump for cryogenic fluid that allows for further cooling of the output fluid.

[0010] To this end, the invention relates to a piston pump for liquefied gases, such as hydrogen, said pump comprising:

[0011] - a supply inlet intended to be connected to a supply tank fluid external to the pump,

[0012] - a filling outlet intended to be connected to a filling device,

[0013] - a suction chamber for receiving the fluid from said inlet, and

[0014] - a fluid degassing chamber communicating with a degassing outlet,

[0015] - a compression and discharge assembly comprising a chamber of compression having a compression outlet fluidly connected to the filling outlet of the piston pump,

[0016] the compression outlet being offset relative to the fluid outlet,

[0017] the compression outlet and the filling outlet being connected to each other by via a connecting portion running at least partially through said degassing chamber.

[0018] According to one embodiment of the invention, the piston pump extends along a main axis and said connecting portion extends at least partially along a secondary axis which may be parallel to the main axis.

[0019] According to one embodiment of the invention, said connecting portion extends over at least 20% of the length of the degassing chamber.

[0020] According to one embodiment of the invention, said connecting portion houses an outlet valve.

[0021] According to one embodiment of the invention, said connecting portion has a body configured to be at least partly in contact with the fluid present in the degassing chamber.

[0022] According to one embodiment of the invention, said compression outlet is formed at least in part in a pump cylinder of the compression and discharge assembly.

[0023] According to one embodiment of the invention, said connecting portion and the cylinder are a single piece.

[0024] According to one embodiment of the invention, said connecting portion is an added part intended to connect the compression outlet to the fluid outlet.

[0025] According to one embodiment of the invention, said connecting portion has a section having a reduced diameter compared to a main diameter of the connecting portion.

[0026] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for which reference should be made to the accompanying drawings. It will be understood that the invention is described in relation to a specific, non-limiting piston pump configuration of the invention. DESCRIPTION OF THE DRAWINGS

[0027] Fig. 1 represents a perspective view of a piston pump for liquefied gases.

[0028] Fig. 2 represents a partial cross-sectional view of the piston pump shown in Fig. 1.

[0029] Fig. 3 represents a cross-sectional view of an enlargement of the connecting section shown in Fig. 2.

[0030] Figures 1 and 2 show a piston pump 1 for liquefied gases, such as hydrogen. The piston pump 1 comprises an inlet body 10 for supplying fluid to the pump 1 and an outlet body 20 for compressing and discharging the fluid.

[0031] The inlet body 10 of the piston pump 1 includes a supply inlet 10A intended to be connected to an external fluid supply tank and a discharge outlet 10B of excess fluid intended to be connected, preferably, to the same supply tank.

[0032] The outlet body 20 of the piston pump 1 includes a degassing outlet 20B and a filling outlet 20A having a shaft A20. As will be described in more detail later, the outlet body 20 of the piston pump 1 includes a pump cylinder 31 linearly guiding a pump piston 32. The linear movement of the pump piston 32 is actuated by means of an actuating rod 33 connected to the pump piston 32 from a control inlet 20C provided on the outlet body 20.

[0033] The excess fluid discharge outlet 10B is intended to return to the reservoir the excess fluid not used for cooling the piston pump 1.

[0034] The degassing outlet 20B is intended to evacuate gases that may result from heating of the fluid that may be produced in the outlet body 20.

[0035] With reference to [Fig.2], a cross-sectional view of the inside of the piston pump 1 is shown.

[0036] The inlet body 10 comprises an inner envelope 10' and an outer envelope 10" delimiting between them an insulation space which can be evacuated to thermally insulate its inner envelope.

[0037] The inner casing 10' of the inlet body 10 is connected to the supply inlet 10A of the piston pump 1 and includes a filter 10C through which the fluid enters.

[0038] The outlet body 20 comprises an inner envelope 20' and an outer envelope 20" also delimiting between them an insulation space which can be evacuated to thermally insulate its inner envelope 20'.

[0039] Advantageously, an insulating material, in particular a multilayer insulator, can be arranged in the insulation space of the inlet body 10 or the outlet body 20.

[0040] The inner casing 20' of the outlet body 20 is connected to the filling outlet 20A and degassing outlet 20B of the piston pump 1 and it partially houses a compression and discharge assembly 30.

[0041] The compression and discharge assembly 30 includes the pump cylinder 31 in which the previously introduced pump piston 32 slides.

[0042] The pump cylinder 31 is arranged in the inner casing 20' of the outlet body 20.

[0043] The inner envelope 20' of the outlet body 20 delimits a volume separated into two distinct chambers 2, 3, namely a suction chamber 2 at a so-called suction pressure and a degassing chamber 3 at a so-called degassing pressure.

[0044] The degassing outlet 20B is fluidically connected to the degassing chamber 3.

[0045] The fluid inlet 10A is fluidly connected to the suction chamber 2.

[0046] These chambers 2, 3 are delimited by the pump cylinder 31 mounted without play in the internal casing 20' of the outlet body 20.

[0047] As illustrated, the pump cylinder 31 houses a pump sleeve 34 in which the pump piston 32 can slide alternately between a position forming a compression chamber filled with fluid and a compression position where the compression chamber is emptied of fluid by a compression outlet 50A passing through the sleeve 34 and the pump cylinder 31. [Fig.2] illustrates the compression position of the pump piston 32.

[0048] The pump cylinder 31 is associated with an inlet valve 35 disposed in the suction chamber 2 and used for the admission of the fluid, and an outlet valve 36 used for the discharge of the pressurized fluid.

[0049] The compression and discharge assembly 30 comprises, among other things:

[0050] - the pump cylinder 31, the pump sleeve 34 and the intake valve 35, solid and coaxial,

[0051] - the pump piston 32 movable axially in the sleeve 34 forming a chamber fluid compression with the intake valve 35.

[0052] The pressurized fluid can be evacuated from the compression chamber by a compression outlet 50A connecting the compression chamber to a connection portion 5 provided for evacuating the pressurized fluid.

[0053] However, the pressurized fluid is heated by the very act of its compression and by the friction generated by the movement of the piston rings 32A of the piston 32 relative to the pump liner 34. While this heating can be limited by its dissipation in the degassing chamber 3 in the form of gas through the degassing outlet 20B, the Cooling the pressurized fluid is not sufficient to guarantee the lowest possible 20A filling outlet temperature.

[0054] To ensure supercooling, the connection portion 5 provides for lengthening the path of the pressurized fluid in the degassing chamber 3 in order to promote its cooling by the fluid included in the degassing chamber 3 along the connection portion 5 housed in the degassing chamber 3.

[0055] As shown, the compression outlet 50A has an axis A50 and the filling outlet 20A has an axis A20. The axes A50 and A20 of the compression outlet 50A and the discharge outlet 20A are advantageously offset from each other, so as to ensure a lengthening of the path of the pressurized fluid from the compression outlet 50A through the degassing chamber 3.

[0056] To ensure this extended path of the pressurized fluid in the degassing chamber 3, a connecting portion 5 is provided to link the compression outlet 50A to the filling outlet 20A. The connecting portion 5 is advantageously designed to pass at least partially through the degassing chamber 3.

[0057] It will be understood that the pressurized fluid is separated from the fluid contained in the degassing chamber 3. The connecting portion 5 however allows a heat exchange between the pressurized fluid and the fluid present in the degassing chamber 3.

[0058] For this purpose, it may be provided that the connecting portion 5 is formed of a body 51 of which at least a part of its outer wall is in contact with the fluid present in the degassing chamber 3. In this way, it is possible to optimize the cooling of the compressed fluid with the help of the fluid present in the degassing chamber, by dissipating heat through the walls of the connecting portion 5.

[0059] The body 51 of the connecting portion 5 advantageously has a reduced cross-section 51, in order to generate an additional external surface in contact with the fluid of the degassing chamber 3.

[0060] As shown in [Fig.3], said connecting portion 5 has a reduced section 51 having a diameter D2 reduced in relation to a main diameter DI of the connecting portion 5.

[0061] The connecting portion 5 extends preferentially along a secondary axis Al parallel to the main axis A0 of the piston pump 1. It may be provided that the connecting portion 5 extends over at least 20% of the length L of the degassing chamber 3.

[0062] The compression outlet 50A opens into an inlet channel 51 formed in the body 50 of said portion 5. The inlet channel 51 can be bent to modify the path of the compression fluid from a flow direction parallel to the axis A50 of the compression outlet 50A to a flow direction parallel to the secondary axis Al of said portion 5.

[0063] The connection portion 5 advantageously houses the outlet valve 36 used for discharging the pressurized fluid.

[0064] As shown, the inlet channel 51 opens onto the outlet valve 36. The arrangement of the outlet valve 36 in said portion 5 advantageously optimizes the space it occupies in the piston pump 1.

[0065] An outlet channel 52 is also formed in the body 50 of said portion 5. The outlet channel 52 can also be bent so as to modify the path of the compression fluid from a flow direction parallel to the secondary axis Al of said portion 5 to a flow direction parallel to the axis A20 of the filling outlet 20A.

[0066] The body 51 may include a leg 53 provided to possibly cooperate with the degassing outlet 20. Advantageously, this leg 53 is provided to form part of the filling outlet 20A.

[0067] It may be provided that the connecting portion 5 is an added part, that is to say a part separate from the pump cylinder 31, or alternatively a part formed in one piece with the pump cylinder 31. In the latter case, the leg 53 can be separated from the body 51 of said portion 5, so as to facilitate the assembly of the pump 1.

[0068] We will now describe the operation of the piston pump 1 shown equipped with the improvements according to the invention.

[0069] Before the piston pump 1 starts, the fluid enters the suction chamber 2 via the supply inlet 10A of the inlet body 10, and any excess returns to the reservoir via the excess fluid discharge outlet 10B. The fluid cools the suction chamber 2 and the inlet chamber 4 by passing, on the one hand, through the filter 10C. As long as the suction chamber 2 is not completely cooled, the fluid returns to the reservoir, carrying with it a fraction of the gas generated by contact with the components to be cooled.

[0070] Degassing is carried out via the degassing outlet 20B as long as the degassing chamber 3 is not cooled below the saturation temperature of the fluid.

[0071] Once the suction chamber 2 and the degassing chamber 3 have cooled down, the pump 1 can be started.

[0072] When the piston actuating rod 33 is pulled by a drive system, it causes the piston 32 to move backward, the intake valve 35 opens, causing the fluid to be drawn into the compression chamber from the intake chamber 4 (i.e., fluid contained in the suction chamber 2) via the intake passages 35A of the intake valve 35.

[0073] The aspirated fluid fills the compression chamber until the piston 32 reaches the end of its stroke. The return of the piston 32 causes the valve 35B to close and compresses the fluid contained in the compression chamber until the outlet valve 36, located in the connecting portion 5, opens. The pressurized fluid then flows through the connecting portion 5. The walls of the body 51 of said portion 5 allow heat exchange between the pressurized fluid and the fluid present in the degassing chamber 3, thus facilitating the dissipation of heat from the accumulated pressurized fluid. The heat thus transferred to the fluid in the degassing chamber 32 can then be dissipated by evaporation as a gas via the degassing outlet 20B.

[0074] The pressurized fluid at the outlet of the outlet valve 36, thus cooled, can be returned to the discharge through the filling outlet 20A of the outlet body 20 via the compression outlet 50A.

[0075] Although the present description refers to specific embodiments, modifications may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

Claims

Demands

1. Piston pump (1) for liquefied gases, such as hydrogen, said pump (1) comprising: - a supply inlet (10A) intended to be connected to a fluid supply reservoir external to the pump (1), - a filling outlet (20A) intended to be connected to a filling device, - a suction chamber (2) for receiving the fluid from said inlet (10A), and - a fluid degassing chamber (3) communicating with a degassing outlet (20B), - a compression and discharge assembly (30) comprising a compression chamber having a compression outlet (50A) fluidly connected to the filling outlet (20A) of the piston pump (1), the compression outlet (50A) being offset relative to the filling outlet (20A),the compression outlet (50A) and the filling outlet (20A) being connected to each other via a connecting portion (5) running at least partially through said degassing chamber (3).

2. Piston pump (1) according to the preceding claim, wherein the piston pump (1) extends along a main axis (AO) and said connecting portion (5) extends at least partially along a secondary axis (Al) which may be parallel to the main axis (A).

3. Piston pump (1) according to any one of the preceding claims, wherein said connecting portion (5) extends over at least 20% of the length (L) of the degassing chamber (3).

4. Piston pump (1) according to any one of the preceding claims, wherein said connecting portion (5) houses an outlet valve (36).

5. Piston pump (1) according to any one of the preceding claims, wherein said connecting portion (5) has a body (51) configured to be at least partly in contact with the fluid present in the degassing chamber (3).

6. Piston pump (1) according to any one of the preceding claims, wherein said compression outlet (50A) is formed at least partly in a pump cylinder (31) of the compression and discharge assembly (30).

7. Piston pump (1) according to the preceding claim, wherein said connecting portion (5) and the cylinder are a single piece.

8. Piston pump (1) according to any one of the preceding claims, wherein said connecting portion (5) is an added part intended to connect the compression outlet (50A) to the filling outlet (20A).

9. Piston pump (1) according to any one of the preceding claims, wherein said connecting portion (5) has a section having a diameter (D2) reduced in relation to a main diameter (Dl) of the connecting portion (5).

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