Device for supplying pressurized fluid

Abstract

The invention relates to a fluid-supply device comprising a compression apparatus (1) comprising a pumping apparatus with an enclosure (13) intended to contain a bath (16) of cryogenic fluid, a first and a second compression chamber (3), (4), an intake system (2) admitting to the first compression chamber (3), a transfer system (6) transferring between the first (3) and the second (4) compression chamber, a movable piston (5) for ensuring the compression in the first (3) and second (4) compression chambers, a discharge port (7) for discharging the compressed fluid, an overflow orifice (8) for discharging, from the first compression chamber (3), a surplus of liquid trapped in the first compression chamber (3) during a compression movement of the piston (5) in the first compression chamber (3), a collecting pipe (11) having an upstream end connected to the overflow orifice and a downstream end connected to a receiving volume, the receiving volume comprising a tank (10) forming a storage volume that is separated from the bath (16) by at least one wall.

Description

[0001] Device for supplying fluid under pressure The invention relates to a device for supplying fluid under pressure, for example hydrogen under pressure, for example up to 900 bar.

[0002] Documents FR3122707A1, US3220202A describe known pumping devices.

[0003] The invention relates more particularly to a pressurized fluid supply device comprising a multi-stage fluid compression apparatus including a pumping apparatus, a sealed enclosure intended to contain a cryogenic fluid bath comprising a liquid phase, the upper part of the enclosure being intended to contain a gaseous head, a first compression chamber, a second compression chamber, an inlet system communicating with the first compression chamber configured to allow the entry of fluid to be compressed into said first compression chamber, a transfer system communicating with the first and second compression chambers and configured to allow the transfer of fluid from the first compression chamber to the second compression chamber, a vertically movable piston to ensure the compression of the fluid in the first and second compression chambers,the apparatus further comprising an outlet communicating with the second compression chamber and configured to allow the outlet of compressed fluid, the second compression chamber being delimited by a portion of the piston body and a fixed wall of the apparatus, the piston being movable in translation along a longitudinal direction, in which the inlet system comprises one or more valves configured to ensure the entry of fluid to be compressed into the first compression chamber during an inlet phase and to prevent the outlet of fluid during the compression phase, the apparatus further comprising at least one overflow outlet configured to control the outlet, out of the first compression chamber,to prevent excess liquid from being trapped in the first compression chamber during a compression movement of the piston in the first compression chamber, and to prevent fluid from entering the first compression chamber, the device includes a collection line having an upstream end connected to the overflow orifice and a downstream end connected to a receiving volume to recover at least part of the fluid discharged through the overflow orifice.

[0004] To increase the performance and volumetric efficiency of liquid hydrogen pumps, good thermodynamic quality of the inlet liquid is essential. This prevents cavitation due to pressure drop and thermal ingress. The high-pressure compression of the liquid drawn from a reservoir containing the pump (the sump) is often preceded by a first compression (or pre-compression) stage. This pre-compression is generally a lower compression stage than the second compression stage. This first compression stage draws in nearly saturated liquid at the saturation temperature of the sump and mechanically subcools it by pressurization to ensure proper filling without flash vaporization at the compression stage.

[0005] In the case where the two compression stages are achieved by opposing movements of the same piston, the filling phase of the second compression stage therefore takes place at the same time as the compression in the first stage.

[0006] Since the chamber diameters are different but the piston stroke is identical, the swept volumes can therefore be different (typically the total volume of the first stage is greater than that of the second stage). Assuming that the fluid density remains relatively constant (due to low compressibility in the absence of flash vaporization) during admission into the second stage, it may be essential to evacuate the excess pressurized liquid from the first compression chamber.

[0007] It is known to provide lights or channels connecting the first compression chamber and the bath to naturally evacuate this excess fluid into the bath.

[0008] In particular, it is possible to provide at least one overflow port equipped with an overflow valve configured to control the discharge, from the first compression chamber, of excess liquid trapped in this first compression chamber during a compression movement of the piston in the first chamber, and to prevent fluid from entering. A collection line can be provided to evacuate all or part of this excess.

[0009] The known solutions are not entirely satisfactory. This discharge of excess liquid from the first compression stage directly into the bath can generate vaporization gas.

[0010] Other parts of known devices generate vaporization gases.

[0011] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0012] One objective of the invention may be, in particular, to optimize the flow rate of vaporized gas generated by limiting the evaporation of the liquid in the bath while improving the pumped flow rate and maintaining good fluid quality at the pump inlet. To this end, the device according to the invention, which otherwise conforms to the generic definition given in the preamble above, is essentially characterized in that the receiving volume comprises a tank forming a storage volume that is separated from the bath by at least one wall.

[0013] Furthermore, embodiments of the invention may include one or more of the following features: the tank is located within the volume of the enclosure,

[0014] The tank is mounted around a casing of the device; the tank forms a tubular sheath of thermal insulation around the device, with at least part of the surface of the casing being in contact with the fluid in the tank.

[0015] The tank is open at its upper end and communicates with the upper part of the enclosure designed to contain a gaseous ceiling.

[0016] The tank is located outside the enclosure.

[0017] the tank contains or supplies another pumping device of the system, for example of the single-stage compression type,

[0018] The tank is under pressure, for example between 3 and 30 bar.

[0019] The upper end of the tank and / or the upper end of the enclosure is connected to a cryogenic fluid reservoir of the device via a set of pipes fitted with valve(s) to transfer vaporization gas.

[0020] The device includes a liquid supply line connecting the cryogenic fluid reservoir to the enclosure and configured to supply liquid into the enclosure; the overflow port is fitted with an overflow valve configured to control the exit, out of the first compression chamber, of excess liquid trapped above a determined pressure threshold and to prevent the entry of fluid into the first compression chamber.

[0021] 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.

[0022] Other features and advantages will become apparent upon reading the description below, which refers to the figures in which:

[0023] Brief description of the figures The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0024] [Fig. 1] is a schematic and partial vertical cross-sectional view illustrating an example of the structure and operation of a detail of a two-stage compression pumping device of a pressurized fluid supply device according to the invention,

[0025] [Fig. 2] is a schematic and partial view of another example of the structure and operation of a pressurized fluid supply device according to the invention.

[0026] Detailed description

[0027] In all the figures, the same references refer to the same elements.

[0028] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Simple features from different embodiments can also be combined and / or interchanged to provide other embodiments.

[0029] The fluid compression apparatus 1 shown in [Fig. 1] comprises two compression stages in series achieved by the same piston 5 driven in a reciprocating motion by a drive element 20.

[0030] Device 1 includes in particular a first compression chamber 3 (at relatively low pressure) and a second compression chamber 4 (at relatively high pressure).

[0031] The apparatus 1 includes an intake system 2 communicating with the first compression chamber 3 and which is configured to permit the entry of fluid to be compressed into said first compression chamber 3.

[0032] The intake system 2 includes, for example, at least one of the following: one or more check valves, one or more orifices or light(s), at least one flat disc valve or any other device or valve allowing the entry of fluid to be compressed into the first compression chamber 3 during an intake phase (here, the upward movement of piston 5) and preventing the exit of fluid during the compression phase (here, the downward movement of piston 5).

[0033] In particular, this inlet system 2 (valve(s) and / or other) can be configured to open in the event of a predetermined pressure differential between its two ends. Furthermore, the first chamber 3 can optionally be equipped with a valve or other safety device configured to limit the pressure within the chamber below a predetermined safety threshold.

[0034] Device 1 also includes a non-return transfer system 6 communicating with the first 3 and second 4 compression chambers and configured to allow fluid transfer from the first 3 compression chamber to the second 4 compression chamber (during and / or at the end of the fluid compression phase in the first 3 compression chamber) but which remains closed during the compression phase in the second 4 compression chamber. This transfer system 6 may be of the same type as that of the inlet system 2.

[0035] Device 1 includes a piston 5 that moves in translation to ensure the compression of the fluid in the first 3 and second 4 compression chambers (as detailed above and below).

[0036] The apparatus 1 further includes a discharge port 7 communicating with the second compression chamber 4 and configured to allow the discharge of high-pressure compressed fluid from the second compression chamber 4 (during or at the end of the compression phase in this chamber 4). The discharge port 7 may be provided with a non-return system which may be of the same type as that of the inlet system 2 (for example, closed as long as the pressure differential between the second compression chamber 4 and the outside is below a predetermined threshold).

[0037] As illustrated, the second 4th compression chamber can be delimited by a portion of the piston body 5 and a fixed wall of the device. The piston 5 is movable in translation along a longitudinal direction A, for example vertical in the operating configuration.

[0038] As illustrated, the piston 5, for example, comprises a tubular portion mounted around a fixed central guide 13. One end of the central guide 13 forms, for example, a fixed wall delimiting part of the second compression chamber 4. The device 1 includes a sealing system 21 formed between the central guide 8 and the piston 5 (ring(s), gasket(s), or other). Depending on the longitudinal and vertical direction of translation of the piston 5, the intake system 2 is preferably located at a first lower end of the device 1, the discharge port 7 is located at a second upper end of the device, and the transfer system 6 is located between the intake system 2 and the discharge port 7.

[0039] The discharge port 7 may be located at the lower end of the central guide 13 (fixed upper end of the second compression chamber 4). The apparatus 1 may include a compressed gas discharge line 22 comprising a first lower end connected to this discharge port 7 and a second upper end located at the top of the apparatus 1 for collecting the high-pressure compressed fluid.

[0040] As illustrated, one end of the piston 5 forms a mobile fluid compression surface in the first 3 compression chamber while the tubular portion of the piston 5 forms a mobile sleeve which cooperates with the terminal end of the central guide 13 to form a fluid compression system in the second 4 compression chamber (in this second compression stage the terminal end of the central guide 13 thus forms a fixed piston cooperating with a mobile sleeve).

[0041] As illustrated, the first compression chamber 3 can be formed within a tubular cavity or fixed chamber that is closed at its lower end. The first compression chamber 3 can thus be delimited at its lower end by this fixed lower cavity. The inlet system 2 can be located at one lower end of the lower cavity.

[0042] The first compression chamber 3 can thus be delimited in its upper part by a lower end of the piston 5 and a sealing system (rings or other) formed between the piston 5 and a wall of the lower cavity 14.

[0043] Preferably, the first compression chamber 3 is configured to facilitate gas escape through ports or valves. For example, as schematically shown, one or more ports 18 (or orifices) may be provided in the upper part of the lower cavity (or any portion of the fixed wall delimiting at least part of the first compression chamber 3). These ports 18 may be designed so that, when the piston 5 uncovers them (piston 5 above at least part of the ports 18), communication is established between the first compression chamber 3 and the outside. Thus, during the intake stroke (expansion of chamber 3), any gas present in the first compression chamber 3 can escape through these ports 18 and be replaced by liquid from the surrounding bath. This ensures a completely liquid intake.Furthermore, during the compression phase (piston 5 plunging into the second compression chamber 3), these ports 18 can release excess liquid by controlling the volume of liquid trapped within them (this volume can be determined by the longitudinal position of the ports 18). Then, piston 5 continues its compression stroke in the first compression chamber 3, and the ports 18 no longer communicate with the compressed volume (which is isolated from the bath 16).

[0044] As illustrated, the device 1 includes an overflow port 8 preferably equipped with an overflow valve 9, for example located at the lower end of the first compression chamber 3. This overflow valve 9 is configured to control the discharge, out of the first compression chamber 3, of excess liquid trapped in the first compression chamber 3 during a compression movement of the piston 5 in the first compression chamber 3 and to prevent the entry of fluid into the first compression chamber 3 via the overflow port 8.

[0045] The device 1 includes a collection pipe 11 having an upstream end connected to the discharge valve 9 and a downstream end connected to a receiving volume to recover at least part of the fluid discharged by the overflow valve 9.

[0046] This receiving volume includes a tank 10 located in the volume of the enclosure 13 and forming a storage volume which is separated from the bath 16 by at least one wall.

[0047] The tank 10 can be mounted around a fixed tubular box 12 of the device 1. This box can surround the piston and can delimit at one of its ends the first compression chamber 3.

[0048] This tank 10 can thus form a tubular sheath filled with liquid, providing thermal insulation around the device. For example, at least part of the outer surface of the casing 12 is in contact with the fluid in the tank 10.

[0049] As illustrated, the tank 10 can be opened at its upper end in the enclosure 13 and can thus communicate with the upper part of the enclosure 13 intended to contain a gaseous sky.

[0050] This structure allows the fluid exiting the neck of the overflow ports 8 to be used to thermalize the body of the compression device and for example the piston liner 5. This allows a flow of fluid to be used which can be considered as a source of vaporization gas without modifying the mixture at the intake and ports 8.

[0051] This tank forms an enclosure protecting the pump's housing 12.

[0052] This limits heat transfer from the casing 12 and the jacket to the bath fluid. This does not disturb the bath at the inlet 8, 9 and the ports 8.

[0053] The collection pipe(s) 11 collect and direct these leaks of pressurized fluid directly higher up in the enclosure 13. This prevents heat exchange between the bath liquid and this hotter, more turbulent leak. This also limits the vaporization gases created by the evaporation of the liquid.

[0054] In the embodiment of [Fig. 2], the tank 10 is located outside the enclosure 13.

[0055] The tank 10 can be used, for example, to supply another pumping device 14. In the example shown, this tank 10 contains a submersible pump 14, for example, a single-stage compression pump. The tank 10, which can be pressurized, for example, to between 3 and 7 bar, can form a reservoir for this additional pumping device.

[0056] As illustrated, the upper end of the tank 10 and the upper end of the enclosure 13 can be connected to a cryogenic fluid reservoir 16 of the device via a set of lines 17, 38 equipped with valves 27, 28. This allows vaporization gas to be transferred to this reservoir 16 (source). This gas return can be regulated by a valve to maintain a liquid level in the enclosure or tank 10. A liquid supply line 19 can also connect the cryogenic fluid reservoir 16 to the enclosure 13 to supply liquid to the enclosure 13.

[0057] The discharge outlets 29, 30 of the pumping units 1, 14 can be separate or mixed. The first two-stage pumping unit 1 can allow, for example, the compression of hydrogen in liquid form, at a pressure between 1 bar and 10 bar (first stage) and then up to a pressure of 900 bar for example (second stage).

[0058] An operating sequence can proceed as follows. The filling of the first compression chamber 3 can be carried out by one or more inlet valves 2 and by one or more ports 18.

[0059] As piston 5 moves downward, the liquid is forced out of ports 18. The vacuum created in the second compression chamber 4 allows this second compression chamber 4 to be pre-filled. As long as ports 18 are not covered by piston 5, excess hydrogen is forced out of the first compression chamber 3 through these ports 18. When these ports 18 are covered, the liquid hydrogen is trapped in the first compression chamber 3.

[0060] The molecules can either be transferred into the second compression chamber 4 or discharged via the overflow valve 9, which can be set to a predetermined value. Since the total volume of the second compression chamber 4 is preferably less than that of the first compression chamber 3, when all the openings 18 are covered, the pressure in both compression chambers increases. The overflow discharged through the overflow valve is collected, at least in part, as described above.

[0061] This quantity of discharged fluid is thus compressed isentropically from the pressure of the chamber 13 to the discharge pressure of the relief valve 9. That is to say, this creates a net positive suction head (NPSH).

[0062] This allows for a pressure margin at saturation.

[0063] For single-stage cryogenic hydrogen compression pumps, this has an influence. For a NPSH of approximately 2 bar, the volumetric efficiency of the single-stage compression pump increases from 46% to 66%.

[0064] The NPSH supplied by the first pumping unit 1 can be, for example, between 3 and 7 bar. From 5 bar NPSH, the estimated volumetric efficiency is greater than 80%. In this example in [Fig. 2], the additional single-stage pump 14 is also immersed in a bath in its tank 10. This pump 14 then operates at a higher pressure (corresponding to the pressure of the relief valve 9 of the first two-stage pump 1).

[0065] Since the bath pressure is higher than that of the reservoir 16, a driving pressure is available to circulate the vaporization gas from the pump. The quantity of fluid collected (discharged) to the tank 10 can be adjusted, for example, according to the pumping capacity of the additional single-stage compression pump 14.

[0066] This configuration allows for the collection of fluid discharged from the two-stage pump while limiting the generated vaporization gas. This flow can be the NPSH thus created. This enables significant volumetric efficiencies to be achieved in a single-stage compression pump that utilizes it.

Claims

Demands

1. A device for supplying fluid under pressure comprising a multi-stage fluid compression apparatus (1) including a sealed enclosure (13) intended to contain a cryogenic fluid bath (16) having a liquid phase, the upper part of the enclosure (13) being intended to contain a gaseous head, a first compression chamber (3), a second compression chamber (4), an inlet system (2) communicating with the first compression chamber (3) configured to permit the entry of fluid to be compressed into said first compression chamber (3), a transfer system (6) communicating with the first (3) and second (4) compression chambers and configured to permit the transfer of fluid from the first compression chamber (3) to the second (4) compression chamber,a movable piston (5) for compressing the fluid in the first (3) and second (4) compression chambers, the apparatus (1) further comprising a discharge orifice (7) communicating with the second compression chamber (4) and configured to allow the discharge of compressed fluid, the second (4) compression chamber being delimited by a portion of the body of the piston (5) and a fixed wall (13) of the apparatus, the piston (5) being movable in translation along a longitudinal direction (A), in which the inlet system (2) comprises one or more valves (2) configured to ensure the entry of fluid to be compressed into the first compression chamber (3) during an inlet phase and to prevent the discharge of fluid during the compression phase, the apparatus (1) further comprising at least one overflow orifice (8) configured to control the discharge, out of the first compression chamber (3),of excess liquid trapped in the first compression chamber (3) during a compression movement of the piston (5) in the first chamber (3) of, compression and to prevent the entry of fluid into the first compression chamber (3), the apparatus (1) comprising a collection conduit (11) having an upstream end connected to the overflow orifice and a downstream end connected to a receiving volume to recover at least part of the fluid discharged through the overflow orifice (8), characterized in that the receiving volume comprises a tank (10) forming a storage volume which is separated from the bath (16) by at least one wall, characterized in that the piston (5) is vertically movable and in that the overflow orifice (8) is distinct from the inlet system (2) and in that the overflow orifice (8) and the inlet system are immersed in the bath (16) of the tank (13).

2. Device f according to claim 1, characterized in that the tank (10) is located in the volume of the enclosure (13).

3. Device f according to claim 2, characterized in that the tank (10) is mounted around a casing (12) of the apparatus (1).

4. Device f according to claim 3, characterized in that the tank (10) forms a tubular thermal insulation sheath around the device, at least a part of the surface of the casing (12) being in contact with the fluid of the tank (10).

5. Device f according to any one of claims 2 to 4, characterized, characterized in that the tank (10) is open at its upper end and communicates with the upper part of the enclosure (13) intended to contain a gaseous ceiling.

6. Device f according to claim 1, characterized in that the tank (10) is located outside the enclosure (13).

7. Device f according to claim 6, characterized in that the tank (10) contains or supplies another pumping apparatus (14) of the device f, for example of the single-stage compression type.

8. Device f according to claim 7, characterized in that the tank (12) is under pressure, for example between 3 and 30 bar.

9. Device f according to any one of claims 6 to 8, characterized in that the upper end of the tank (10) and / or the upper end of the enclosure (13) is connected to a reservoir (16) of cryogenic fluid of the device f via a set of pipes (17, 38) fitted with valve(s) (27, 28) for transferring vaporization gas.

10. Device f according to claim 9, characterized in that it comprises a liquid supply line (19) connecting the cryogenic fluid reservoir (16) to the enclosure (13) and configured to supply liquid into the enclosure (13).

11. Device f according to any one of claims 1 to 10, characterized in that the overflow orifice (8) is provided with an overflow valve (9) configured to control the exit, out of the first compression chamber (3), of an excess of trapped liquid above a determined pressure threshold and to prevent the entry of fluid into the first compression chamber (3).

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