Fluid compression apparatus and method

Abstract

To provide a fluid compression apparatus capable of compressing a fluid to a very high pressure at the outlet of a second compression stage.SOLUTION: A fluid compression apparatus 1 comprises a sealed enclosure 13 intended to contain a bath 16 of cryogenic fluid, a first compression chamber 3, a second compression chamber 4, an intake system 2 for admission into the first chamber, and a system 6 for transfer from the first chamber to the second chamber. The apparatus further comprises a communicating discharge orifice 7 for compressed fluid to leave the second chamber, and the apparatus further comprises a discharge orifice provided with a valve 9 for discharge from the first compression chamber to the bath to let surplus liquid leave during compression of the fluid in the first chamber. The discharge orifice communicates with the enclosure via at least one flow retarder 10 configured to attenuate the speed and / or intensity of the discharged liquid flow by limiting its pressure drop.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fluid compression device and method.

[0002] More particularly, the present invention is a fluid compression device having a plurality of compression stages, intended to include a cryogenic fluid tank having a liquid phase, and an enclosed housing intended such that the upper part of the enclosed housing includes a gas head space, a first compression chamber, a second compression chamber, an intake system in communication with the first compression chamber and configured to allow fluid to enter the first compression chamber, and a transfer system in communication with the first compression chamber and the second compression chamber and configured to transfer the fluid pre-compressed in the first compression chamber to the second compression chamber. The device further includes a discharge orifice in communication with the second compression chamber and configured to allow the fluid compressed in the second compression chamber to exit. Here, the intake system includes one or more valves configured to ensure that the fluid to be compressed during the intake phase enters the first compression chamber and prevent the fluid from exiting during the compression phase. The device further includes a discharge orifice that allows communication between the first compression chamber and the tank so as to discharge excess liquid trapped in the first compression chamber during compression of the fluid in the first compression chamber. The present invention relates to a fluid compression device.

Background Art

[0003] To improve the performance and volumetric efficiency of a liquid hydrogen pump, it is essential that the thermodynamic properties of the liquid at the inlet are good. This is to avoid cavitation due to pressure drop and heat input. In many cases, there is a first compression stage (or pre-compression) prior to the high-pressure compression of the liquid withdrawn from a tank (tank or sump) containing the pump. This pre-compression is generally at a lower level of compression than the second compression stage. To achieve good filling without "flash" evaporation in the compression stage, this first compression stage draws a quasi-saturated liquid at the saturation temperature of the tank and mechanically subcools it by pressurization.

[0004] In particular, when the two compression stages are realized by the opposite movement of one and the same piston, the filling phase of the second compression stage is thus carried out simultaneously with the compression in the first stage.

[0005] Since the piston strokes are identical but the chamber diameters are different, the displacement volumes may be different (typically, the volume of the first stage is larger than the volume of the second stage). Assuming that the density of the fluid remains relatively constant while entering the second stage (since the compression ratio is low in the absence of flash evaporation), it may be essential to discharge some of the pressurized liquid from the first compression chamber.

[0006] It is known to provide a port or channel establishing communication between the first compression chamber and a tank to naturally discharge this surplus fluid into the tank. This discharge of the excess liquid from the first compression stage may generate evaporation gas in the tank. SUMMARY OF THE INVENTION

[0007] The object of the present invention is to overcome all or some of the drawbacks of the prior art described above.

[0008] For this purpose, a device according to the invention, according to its general definition given above in the preamble otherwise, essentially has a discharge valve configured to control the discharge of liquid through a discharge orifice and prevent fluid from entering the first compression chamber through the discharge orifice, and the discharge orifice communicates with a housing via at least one flow retarder configured to reduce the velocity and / or intensity of the discharged liquid flow by limiting its pressure drop.

[0009] Furthermore, embodiments of the invention may include one or more of the following features, namely, - The flow retarder comprises at least one of a set of diffuser holes and a nozzle made of a porous material having a permeability greater than 5 darcies. - The flow retarder preferably comprises at least one of a nozzle made of a porous sintered material, for example bronze or stainless steel, which is preferably cylindrical or conical. - The retarder has a length between 15 mm and 450 mm and preferably a diameter between 10 mm and 80 mm. - The discharge orifice communicates with the housing via at least one discharge duct opening into the housing within the tank such that the discharge orifice is positioned within and / or above the liquid level of the tank of the housing. - The discharge duct has a portion extending into the housing parallel to and / or transverse to the vertical direction. - The discharge duct extends from the bottom to the top of the housing. - The discharge orifice communicates with the housing via a plurality of discharge ducts opening into the housing. - The device comprises a piston capable of moving to compress the fluid in the first compression chamber and the second compression chamber during alternating opposite movement. - The container includes a tank composed of a cryogenic liquid such as liquefied hydrogen.

[0010] The present invention also relates to a method of pumping a cryogenic fluid using such a device, wherein the container includes a tank of liquefied cryogenic fluid, and the method includes the steps of introducing liquid into the first compression chamber via an intake system, compressing the fluid in the second compression chamber, then introducing fluid into the second compression chamber via a transfer system, and compressing the fluid in the first compression chamber, during which excess fluid is discharged from the first compression chamber to the tank via a discharge orifice and at least one retarder.

[0011] The present invention may also relate to any alternative device or method including any combination of the above or below features within the scope of the claims.

[0012] Other specific features and advantages will become apparent upon reading the following description given with reference to the drawings.

[0013] The present invention will be better understood by reading the following description given by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0015] Throughout the drawings, the same reference refers to the same element.

[0016] In this detailed description, the following embodiments are examples. The description refers to one or more embodiments, but this does not mean that the features apply only to a single embodiment. The individual features of different embodiments can also be combined and / or replaced to provide other embodiments.

[0017] The fluid compression device 1 depicted in [Figure 1] comprises a series of two compression stages.

[0018] Device 1 specifically includes a first compression chamber 3 (compressed at a relatively low pressure) and a second compression chamber 4 (compressed at a relatively high pressure).

[0019] Device 1 includes an intake system 2 communicating with the first compression chamber 3, and the intake system 2 is configured to allow the fluid (liquid) to be compressed to enter the first compression chamber 3.

[0020] The intake system 2 includes, for example, at least one of the following, namely, one or more check valves, one or more orifices or ports, at least one flat disc valve, or any other device or valve that allows the fluid to be compressed to enter the first compression chamber 3 during the intake phase and prevents the fluid from exiting during the compression phase.

[0021] Specifically, this intake system 2 (valve and / or the like) may be configured to open when a given pressure difference exists between its two ends. In addition, the first chamber 3 may optionally include a relief valve or other safety element configured to limit the pressure within the chamber below a given safety threshold.

[0022] As illustrated, the second compression stage (by the second compression chamber 4) does not necessarily need to be immersed in the liquid tank 16, and it may be partially or entirely above the tank 16.

[0023] Preferably, the first compression stage (by the first compression chamber 3) does not necessarily need to be immersed in the liquid tank 16, and at least the intake system is immersed in or connected to the liquid tank.

[0024] The device 1 further comprises a check transfer system 6 that communicates with a first compression chamber 3 and a second compression chamber 4 and is configured to transfer the fluid compressed in the first compression chamber 3 to the second compression chamber 4 (during and / or at the end of the phase of compressing the fluid in the first compression chamber 3), but remains closed during the compression phase in the second compression chamber 4. This transfer system 6 may be of the same type as the intake system 2.

[0025] The device 1 can comprise a piston 5 that can perform a translational movement (actuated by a drive member) by means of an alternating movement in order to compress the fluid in the first compression chamber 3 and the second compression chamber 4. For example, the compression movement in one chamber ensures, at the same time, the inflow into the other chamber (and vice versa).

[0026] The device 1 further comprises a discharge orifice 7 that communicates with the second compression chamber 4 and is configured to allow the high-pressure compressed fluid to exit from the second compression chamber 4 (during or at the end of the compression phase in this chamber 4). The discharge orifice 7 may be provided with a check system, and the check system may be of the same type as the intake system 2 (for example, it remains closed as long as the pressure difference between the second compression chamber 4 and the outside is lower than a given threshold).

[0027] The device 1 may comprise a compressed gas discharge duct that comprises a first lower end connected to this discharge orifice 7 and a second upper end installed at the upper part of the device 1 that collects the compressed high-pressure fluid.

[0028] Preferably, the first compression chamber 3 is configured to facilitate the escape of gas through a port or a valve.

[0029] For example, one or more ports and / or orifices (not shown) may be formed in any part of the wall defining at least a portion of the first compression chamber 3. These ports may be provided such that during the intake phase (when the chamber 3 is expanding), any gas present within the first compression chamber 3 can escape through these ports and yield its place to the liquid from the surrounding tank. This ensures complete filling by the liquid during inflow. Additionally, during the compression phase, these ports can allow excess liquid to escape, thereby measuring the volume of liquid trapped therein (this volume can be determined by the position of port 26).

[0030] As illustrated, the compression device 1 may comprise a thermally insulated sealed housing 13 that includes a cryogenic cooling fluid tank 16. Specifically, the first compression chamber 3, and optionally the second compression chamber 4, may be immersed in the liquid phase. The upper part of the housing 16 may have a gas headspace that collects any leaks within the device 1.

[0031] The compression device 1 further comprises a discharge orifice configured to enable fluid communication between the first compression chamber 3 and the tank 16 and to discharge the excess liquid trapped within the first compression chamber 3 during compression therein.

[0032] The discharge valve 9 is preferably provided to control the discharge of liquid through the discharge orifice and to prevent fluid from entering the compression chamber 3 through the discharge orifice.

[0033] As illustrated, the discharge orifice communicates with the housing 13 via at least one flow retarder 10 configured to reduce the velocity and / or intensity of the liquid flow being discharged by breaking the jet and by using a relatively large discharge area.

[0034] The retarder 10 is preferably configured to reduce the effects of pressure drops created by dissipation or friction or violent impacts caused by powerful ejection jets. The retarder "breaks" such jets.

[0035] Such a retarder 10 creates a non-sudden flow discharge, thereby stalling, but it converts velocity into pressure rather than pressure drop.

[0036] This limits friction or possible splashing of the liquid towards hot areas of the walls of the intake chamber, which can cause evaporation.

[0037] The flow retarder 10 may comprise, for example, a nozzle of porous material. See FIGS. 1, 2, 3, and 4. For example, the porous sintered material may comprise, for example, a cylindrical or conical sinter made of bronze or stainless steel. The length may be between 15 mm and 450 mm. The diameter may be between 10 mm and 80 mm. The permeability may be greater than 5 Darcy (>5D), where 1 Darcy is 10 -12 m 2 is equal to.

[0038] This allows the discharge plume to "break" without a pressure drop, while also reducing contact of the near-saturated liquid with potentially warmer portions of the vessel 16 or vapor.

[0039] As illustrated, the discharge orifice may communicate with the housing 13 via at least one discharge duct 11 (two in the illustrated example) opening into the housing 13. Each duct 11 may be provided with a retarder 10.

[0040] The one or more exhaust ducts 11 are - in the liquid bath, it may extend horizontally and open, for example, at the bottom of the container 13, - In the liquid tank, it may extend horizontally and then vertically upward, for example, opening at the bottom of the container, see [Figure 3]. - It extends horizontally and then vertically and may open, for example, at the joint between the liquid tank and the gas head space. - It extends horizontally and then vertically and may open, for example, above the liquid tank and the gas head space. Refer to [Figure 1] and [Figure 2].

[0041] The retarder 10 is preferably provided at the downstream end of the discharge duct 11 (in the container / tank).

[0042] Thus, as illustrated, the end of the discharge duct 11 can be directed upward or downward or horizontally.

[0043] Specifically, in order to reduce the contact between the potential bubbles and the liquid in the tank 16, it is possible to direct one or more discharge ducts 11 vertically. In this way, the bubbles are rather directed towards the upper part of the tank and thus towards the gas head space, while the liquid is poured into the liquid phase.

[0044] Upon discharge to the gas portion, the discharged liquid flow can flow out and be slowly poured into the liquid phase. In this way, the heat exchange between the liquid phase and the gas phase is limited. As illustrated, the two discharge ducts 11 can be connected to the same discharge valve 9 via a common chamber.

[0045] In the variant of [Figure 4], the retarder 10 comprises or consists of a tube with a porous surface that extends vertically within the container 13.

[0046] In the variant of [Figure 5], the retarder 10 comprises or consists of a tube perforated with a number of orifices to allow the liquid to flow out. For example, the orifices have dimensions between 0.05 mm and 1 mm.

[0047] In a modification of [[Fig. 6]], the retarder 10 comprises or consists of a tube perforated with a number of orifices arranged in a serpentine manner around at least one of the two compression chambers.

[0048] The present invention is particularly advantageous for pumping hydrogen, for example, to generate a hydrogen stream at a very high pressure (for example, a pressure between 100 and 1000 bar) at the outlet of the second compression stage.

Claims

1. A fluid compression device (1) having a plurality of compression stages, said fluid compression device (1) being a sealed housing (13) intended to include a cryogenic fluid tank (16) having a liquid phase, the upper part of which is intended to include a gas head space, a first compression chamber (3), a second compression chamber (4), an intake system (2) configured to communicate with the first compression chamber (3) and allow fluid to enter the first compression chamber (3), and a transfer system (6) configured to communicate with the first compression chamber (3) and the second compression chamber (4) and transfer the fluid pre-compressed in the first compression chamber (3) to the second compression chamber (4). The fluid compression device (1) further comprises a discharge orifice (7) configured to communicate with the second compression chamber (4) and allow the fluid compressed in the second compression chamber (4) to exit. The intake system (2) comprises one or more valves (2) configured to ensure that the fluid to be compressed during the intake phase enters the first compression chamber (3) and prevent the fluid from exiting during the compression phase. In the fluid compression device (1), the fluid compression device (1) further comprises a discharge orifice that enables communication between the first compression chamber (3) and the tank (16) so as to discharge the surplus liquid captured in the first compression chamber (3) during the compression of the fluid in the first compression chamber (3). The fluid compression device (1) has a discharge valve (9) configured to control the discharge of liquid through the discharge orifice and prevent fluid from entering the first compression chamber (3) through the discharge orifice, and the discharge orifice communicates with the sealed housing (13) via at least one flow retarder (10) configured to reduce the velocity and / or intensity of the discharged liquid flow by limiting its pressure drop. The fluid compression device (1) is characterized in that.

2. The fluid compression device according to claim 1, wherein the flow retarder (10) comprises at least one of a set of diffusion holes and a nozzle made of a porous material having a permeability greater than 5 darcies.

3. The fluid compression device according to claim 1 or 2, characterized in that the flow retarder (10) comprises at least one nozzle made of a porous sintered material, preferably cylindrical or conical, such as bronze or stainless steel.

4. The fluid compression device according to any one of claims 1 to 3, characterized in that the retarder (10) has a length between 15 mm and 450 mm and preferably a diameter between 10 mm and 80 mm.

5. The fluid compression device according to any one of claims 1 to 4, characterized in that the discharge orifice communicates with the sealing housing (13) through at least one discharge duct (11) opening into the sealing housing (13) within the tank (16) such that the discharge orifice is positioned within and / or above the liquid level of the tank of the sealing housing (13).

6. The fluid compression device according to claim 5, characterized in that the discharge duct (11) has a portion extending into the sealing housing (13) parallel to and / or transverse to the vertical direction.

7. The fluid compression device according to claim 5 or 6, characterized in that the discharge duct (11) extends from the bottom to the top of the sealing housing (13).

8. The fluid compression device according to any one of claims 5 to 7, characterized in that the discharge orifice (7) communicates with the sealing housing (13) through a plurality of discharge ducts (11) opening into the sealing housing (13).

9. The fluid compression device according to any one of claims 1 to 8, characterized in that it comprises a piston capable of moving so as to compress the fluid in the first compression chamber (3) and the second compression chamber (4) during reciprocating opposite movements.

10. The fluid compression device according to any one of claims 1 to 9, characterized in that the container includes a tank composed of a cryogenic liquid, such as liquefied hydrogen.

11. A method of pumping a cryogenic fluid using the fluid compression device according to any one of claims 1 to 10, wherein the container (13) includes a tank of liquefied cryogenic fluid. The method includes the steps of introducing a liquid into the first compression chamber (3) via the intake system (2), compressing the fluid in the second compression chamber (4), then introducing a fluid into the second compression chamber (4) via the transfer system (6), and compressing the fluid in the first compression chamber (3), wherein during the step, excess fluid is discharged from the first compression chamber (3) to the tank via the discharge orifice (7) and at least one of the retarders (10).

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