Patent Application
20250237201
This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to French patent application No. FR2400587, filed Jan. 22, 2024, which is herein incorporated by reference in its entirety.
The invention relates to a fluid compression apparatus and method.
To increase the performance and volumetric efficiency of liquid hydrogen pumps, it is essential to have a good thermodynamic quality of the liquid at the intake. This is to avoid cavitation by pressure drop and thermal input. The high-pressure compression of the liquid drawn from a tank containing the pump (bath or sump) is often preceded by a first compression stage (or pre-compression). This pre-compression is generally a compression stage with a lower rate than the second compression stage. This first compression stage draws in quasi-saturated liquid at the saturation temperature of the bath and mechanically subcools it by pressurization in order to achieve good filling without “flash” vaporization at the compression stage.
If the two compression stages are produced by opposite movements of a single piston, the phase of filling the second compression stage therefore takes place at the same time as the compression in the first stage.
Since the diameters of the chambers are different but the piston stroke is identical, the swept volumes can therefore be different (typically the first stage has a larger volume than the second stage). Assuming that the density of the fluid remains relatively constant (because there is little compressibility in the absence of flash vaporization) during the admission into the second stage, it may be essential to discharge some of the pressurized liquid from the first compression chamber.
It is known practice to provide ports or channels connecting the first compression chamber and the bath so as to naturally discharge this surplus fluid to the bath.
This solution is not entirely satisfactory. This discharge of excess liquid from the first compression stage can generate vaporization gas in the bath.
One aim of the present invention is to overcome all or some of the drawbacks of the prior art set out above.
In certain embodiments, the invention relates more particularly to a fluid compression apparatus with a plurality of compression stages, comprising a sealed enclosure intended to contain a bath of cryogenic fluid having a liquid phase, the upper part of the enclosure being intended to contain a gas headspace, a first compression chamber, a second compression chamber, an intake system that communicates with the first compression chamber and is configured to allow fluid for compression to enter said first compression chamber, a transfer system that communicates with the first and second compression chambers and is configured to allow the transfer of fluid from the first compression chamber to the second compression chamber, and a movable piston for ensuring the compression of the fluid in the first and second compression chambers, the apparatus also comprising a discharge orifice that communicates with the second compression chamber and is configured to allow compressed fluid to leave, the second compression chamber being delimited by a portion of the body of the piston and fixed wall of the apparatus, the piston being able to translate in a first longitudinal direction, wherein the intake system comprises one or more valves configured to ensure that fluid for compression enters the first compression chamber during an intake phase and to prevent fluid from leaving in the compression phase, the apparatus further comprising a discharge orifice allowing communication between the first compression chamber and the bath so as to allow surplus liquid trapped in the first compression chamber to leave during a compression movement of the piston in the first compression chamber.
In an effort to overcome the deficiencies of the prior art discussed, supra,, the apparatus according to the invention, which otherwise corresponds to the generic definition given in the preamble above, is configured such that it has a discharge valve configured to control the discharge of liquid via the discharge orifice and to prevent fluid from entering the compression chamber via the discharge orifice.
In addition, embodiments of the invention can comprise one or more of the following features:
The invention also relates to a method for pumping cryogenic fluid using such an apparatus, wherein the container contains a bath of liquefied cryogenic fluid, the method comprising, simultaneously during a first movement of the piston, a step of admitting liquid into the first compression chamber via the intake system and a step of compressing fluid in the second compression chamber, and then, during a second opposite movement of the piston, a step of admitting fluid into the second compression chamber via the transfer system and a step of compressing the fluid in the first compression chamber during which surplus fluid is discharged from the first compression chamber via the discharge orifice.
The invention can also relate to any alternative device or method comprising any combination of the features above or below within the scope of the claims.
The invention will be understood better from reading the following description and from studying the accompanying figures. These figures are given only by way of illustration and do not in any way limit the invention.
Throughout the figures, the same references relate to the same elements.
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. Individual features of different embodiments can also be combined and/or interchanged to provide other embodiments.
The fluid compression apparatus 1 shown in [
The apparatus 1 particularly comprises a first compression chamber 3 (at relatively low pressure) and a second compression chamber 4 (at relatively high pressure).
The apparatus 1 comprises an intake system 2 that communicates with the first compression chamber 3 and is configured to allow fluid for compression to enter said first compression chamber 3.
The intake system 2 comprises for example at least one of: one or more non-return valves, one or more orifices or ports, at least one flat-disc valve or any other device or valve that allows fluid for compression to enter the first compression chamber 3 during an intake phase (here, the upstroke of the piston 5) and prevents fluid from leaving in the compression phase (here, the downstroke of the piston 5).
In particular, this intake system 2 (valve(s) and/or the like) can be configured to open in the event of a given pressure differential between its two ends. In addition, the first chamber 3 can optionally be equipped with a relief valve or other safety element configured to limit the pressure within the chamber to below a given safety threshold.
The apparatus 1 also comprises a non-return transfer system 6 that communicates with the first 3 and second 4 compression chambers and is configured to allow the transfer of fluid from the first compression chamber 3 to the second compression chamber 4 (during and/or at the end of the phase of compression of the fluid in the first compression chamber 3) but which remains closed during the compression phase in the second compression chamber 4. This transfer system 6 can be of the same type as the intake system 2.
The apparatus 1 comprises a piston 5 that is able to translate in order to ensure the compression of the fluid in the first 3 and second 4 compression chambers (as detailed hereinafter).
The apparatus 1 further comprises a discharge orifice 7 that communicates with the second compression chamber 4 and is configured to allow high-pressure compressed fluid to leave the second compression chamber 4 (during or at the end of the compression phase in this chamber 4). The discharge orifice 7 can be provided with a non-return system, which can be of the same type as the intake system 2 (for example closed as long as the pressure differential between the second compression chamber 4 and the outside is below a given threshold).
As illustrated, the second compression chamber 4 can be delimited by a portion of the body of the piston 5 and a fixed wall of the apparatus. The piston 5 is able to translate in a longitudinal direction A, for example vertical in an operating configuration.
As illustrated, the piston 5 comprises for example a tubular portion mounted around a fixed central guide 12. A terminal end of the central guide 12 forms for example a fixed wall defining part of the second compression chamber 4. The apparatus 1 comprises a sealing system (not shown for the sake of simplicity) formed between the central guide 12 and the piston 5 (piston ring(s), seal(s) or the like). In the longitudinal direction A of translation of the piston 5, the intake system 2 is preferably situated at a first end of the apparatus 1, the discharge orifice 7 being situated at a second end of the apparatus, and the transfer system 6 is situated between the intake system 2 and the discharge orifice 7.
The discharge orifice 7 can be situated at the lower end of the central guide 12 (the fixed upper end of the second compression chamber 4). The apparatus 1 can comprise a compressed gas discharge duct comprising a first, lower end connected to this discharge orifice 7 and a second, upper end situated in the upper part of the apparatus 1 for collecting the compressed high-pressure fluid.
As illustrated, one end of the piston 5 forms a movable surface for compressing the fluid in the first compression chamber 3 while the tubular portion of the piston 5 forms a movable sleeve that collaborates with the terminal end of the central guide 12 to form a system for compressing the fluid in the second compression chamber 4 (in this second compression stage, the terminal end of the central guide 12 thus forms a fixed piston collaborating with a movable sleeve).
As illustrated, the first compression chamber 3 can be formed in a tubular cavity 14 or fixed chamber that is closed at its lower end. The lower part of the first compression chamber 3 can thus be delimited by this fixed lower cavity 14. The intake system 2 can be situated at a lower end of the lower cavity 14.
The upper part of the first compression chamber 3 can thus be delimited by a lower end of the piston 5 and a sealing system (piston rings or the like) formed between the piston 5 and a wall of the lower cavity 14.
Preferably, the first compression chamber 3 is configured to promote the escape of the gas via the ports or valves. For example, as schematically shown, one or more ports 26 (or orifices) can be formed in the upper part of the lower cavity 14 (or any fixed wall portion defining at least part of the first combustion chamber 3). These ports 26 can be provided so that, when the piston 5 uncovers them (when the piston 5 is above at least some of the ports 26) the first compression chamber 3 communicates with the outside. Thus, in the intake phase (as the chamber 3 is becoming larger), any gas that might be present in the first compression chamber 3 can escape via these ports 26 and give up its place to liquid from the surrounding bath. This ensures complete filling with liquid on intake. In addition, in the compression phase (the piston 5 moving down in the second compression chamber 3), these ports 26 can allow the surplus liquid to escape, thereby metering the volume of liquid trapped therein (this volume can be determined by the longitudinal position of the ports 26). The piston 5 then continues its compression stroke in the first compression chamber 3 and the ports 26 no longer communicate with the compressed volume (which is isolated from the bath 16).
As illustrated, the compression apparatus 1 can comprise a thermally insulated sealed enclosure 13 containing a bath 16 of cryogenic cooling fluid. In particular, the first 3 and second 4 compression chambers can be submerged in a liquid phase. The upper part of the enclosure 16 can have a gas headspace that collects any leaks from the apparatus 1.
The compression apparatus 1 further comprises a discharge orifice 8 that allows fluidic communication between the first compression chamber 3 and the bath 16 and is configured to allow surplus liquid trapped in the first compression chamber 3 to leave during a compression movement of the piston 5 in the first compression chamber 3.
A discharge valve 9 is provided to control the discharge of liquid via the discharge orifice 8 and to prevent fluid from entering the compression chamber 3 via the discharge orifice 8.
The discharge valve 9 is for example a non-return valve, for example comprising a shut-off flap acted upon by a spring to a closed position on a seat.
As illustrated in [
The retarder 10 is preferably configured to reduce the effect of pressure drops caused by diffusion or friction or violent shocks due to vigorous discharged jets. The retarder “breaks” such jets.
Such a retarder 10 produces non-sudden discharge of the flow, which loses speed but converts it into pressure rather than into a pressure drop. This limits friction or possible spattering of liquid towards hot areas of the wall of the intake bath that can cause it to evaporate.
The flow retarder 10 can comprise, for example, a nozzle made from porous material, cf. [
This makes it possible to “break” the discharged jet without pressure drop while at the same time reducing the contact of the liquid close to saturation with potentially warmer parts or vapour of the bath 16.
As illustrated, the discharge orifice 8 can communicate with the enclosure 13 via at least one discharge duct 11 (two in the examples illustrated) emerging in the enclosure 13.
The discharge duct(s) 11 can extend:
If a retarder 10 is provided, it is preferably provided at the downstream end of the discharge duct 11 (in the container/bath).
Thus, as illustrated, the ends of the discharge ducts 11 can be oriented upwards or downwards or horizontally.
In particular, it is possible to orient the discharge duct(s) 11 vertically in order to reduce contact between the potential bubbles and the liquid of the bath 16. In this way, the bubbles are directed rather towards the top of the bath and therefore towards the gas headspace while the liquid flows into the liquid phase.
In the event of discharge into the gas part, the discharged liquid flow can trickle and flow slowly 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 a single discharge valve 9 via a common chamber.
In the variant in [
In the variant in [
In the variant in [
The invention is particularly advantageous for pumping hydrogen, for example so as to produce a flow of hydrogen at very high pressure at the outlet of the second compression stage (pressure between 100 and 1,000 bar for example).
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR 2400587 | Jan 2024 | FR | national |
