INSULATED AND FLEXIBLE PIPE SYSTEM FOR THE TRANSPORT OF CRYOGENIC, REFRIGERANT AND / OR HEAT TRANSFER FLUIDS.

Abstract

The present invention relates to a high-performance, thermally efficient, insulated and flexible piping device for transporting cryogenic, refrigerant, and / or heat transfer fluids. The device consists of one or more inner tubes (1) through which one or more cryogenic fluids circulate and which are contained within an outer tube (2), characterized in that the space between the inner tube(s) (1) and the outer tube (2) is filled with spheres or microspheres (3). The space in which the spheres or microspheres are located can be either pressurized with an inert gas or, conversely, evacuated to enhance thermal insulation.All or part of the inner tube(s) (4) and / or the outer tube (5) may be corrugated to allow for their contraction under low stress and to increase the flexibility of the line, particularly when operating conditions require a certain thickness of the inner tube(s) and / or the outer tube. The entire inner tube(s) and outer tube assembly may be inserted into an insulating sheath (6).

Description

Title of the invention: INSULATED AND FLEXIBLE PIPELINE DEVICE FOR FLUID TRANSPORT CRYOGENIC, REFRIGERANTS AND / OR HEAT TRANSPORTERS.

[0001] The present invention relates to a high-performance, thermally efficient, insulated and flexible piping device for transporting cryogenic, refrigerant, and / or heat transfer fluids. The term "piping" here refers to a pipe in one or more sections, capable of transferring one or more fluids, liquid or gaseous, or in the form of plasma or in a multiphase state, of the same or different types. The term "flexible" refers to any part or section that is flexible, capable of bending and able to withstand deformation during assembly and / or operation without breaking, as opposed to a rigid system that does not deform or deforms very little, and breaks when subjected to significant displacement.

[0002] The challenges of piping for transporting cryogenic fluids, refrigerants, and / or high-performance heat transfer fluids require finding a compromise between safety, thermal performance, reliability (particularly mechanical), and the costs of purchasing, installing, and maintaining the system. The nature of the fluid(s) being transported is naturally important in terms of the risk of failure and compatibility with the materials used.

[0003] This problem is particularly evident in the context of cryogenic fluid transfer lines. It involves finding a design that simultaneously minimizes heat loss, ensures the retraction of the cryogenic fluid piping during cooling, and guarantees the integrity of the line, especially in the event of insulation failure. Furthermore, the risk of failure is particularly high in the context of liquid hydrogen transport. Current cryogenic fluid transport technologies are based on one or more internal cryogenic fluid transfer lines, individually or in groups, and contained within an outer casing under high vacuum. These phases of insulation of the internal tubes with a multilayer insulator are called "superinsulation."These processes are meticulous, most often carried out manually, resulting in numerous imperfections (thermal short circuits and / or screening holes) and representing a significant source of installation costs. The internal pipe(s) are held in position relative to the outer casing by means of fixed or sliding internal supports that allow movement of the inner tube relative to the outer casing. These supports, often called "spacers," must be rigid enough to withstand stress. Significant effort and thin walls are required to limit heat exchange between the "cold" and "hot" zones. The use of a bellows is one solution to compensate for the thermal contraction of the internal piping when it cools and to limit stresses within the pipeline. However, bellows only offer one degree of freedom of movement: longitudinal. Furthermore, radial contraction results in stresses, play, or displacement of the internal components. Fixed and sliding external supports (to prevent vacuum failure) hold the outer casing in position within its environment. This design necessitates finding a compromise between thermal performance and the line's robustness. Moreover, it is a rigid structure requiring high precision in manufacturing and assembly, particularly through precise adaptation to the geometry of the surrounding environment.

[0004] The present invention consists of one or more internal tubes (1) through which one or more cryogenic fluids circulate, contained in an external tube (2), and is characterized in that the space between the internal tube(s) (1) and the external tube (2) is filled by solid or hollow spheres or microspheres (3). These spheres or microspheres, whose average diameter can vary from a few tens of micrometers to a few millimeters, can be made of glass, polymer or ceramic material, carbon, or even metallic materials. They may optionally be coated with one or more insulating and / or radiant treatments. The space in which the spheres are located is either pressurized with an inert gas or, conversely, evacuated to promote thermal insulation. The spheres keep the internal tube(s) centered within the outer casing.They contribute to thermal insulation by minimizing conduction through an increase in the path length and a decrease in the cross-sectional area, particularly in the case of hollow spheres or microspheres.

[0005] Due to their high compressive strength, they contribute to the absorption of pressure forces in the internal tubes by transferring part of the stress to the upper tubes or the outer casing. Furthermore, the spheres or microspheres generate a "hydraulic resistance," also called "pressure drop," which delays and limits the flow of any leaks in the internal tube(s), even when the outer casing is under vacuum. In addition, these spheres or microspheres dampen vibrations, whether they originate, for example, from transient phenomena within the fluids or from accelerations experienced by the outer casing or the overall installation. The device is therefore safer.The spheres can rotate on their own axis, move, and slide relative to each other and along the internal tube(s) and the external tube, allowing for relative movement of the tubes and internal elements, as well as the overall flexibility. The material, treatments, and size (diameter and thickness) are also factors. and the quantity (filling density) of the spheres or microspheres will be adjusted according to the mechanical constraints, the degree of flexibility and the level of insulation required.

[0006] The spheres or microspheres will be introduced into the gaps between the internal pipes and the external pipe during the manufacturing of the device or during the final assembly of the device on the permanent installation in situ, either by gravity, by pressure injection, by suction, or by a combination of these techniques. Similarly, to facilitate filling and air evacuation, "vibration" type techniques can be combined with the preceding methods. The principle of insulation using spheres or microspheres is therefore particularly efficient compared to traditional superinsulation technologies. Under certain conditions, one or more traditional "spacer" supports could be added. This solution is particularly necessary when the spheres or microspheres are to be inserted directly into the device during its assembly on a final installation.The "spacers" will then be largely hollowed out to allow the spheres to be filled and the vacuum drawn. In the case where the final installation consists of the assembly of finished and entirely factory-made single sections, two fixed and airtight "spacers" will be placed at the ends of each section to ensure the airtightness of the space in which the spheres and the fluid or vacuum will be contained.

[0007] If the spheres (3) are immersed in an inerting fluid, it is preferable that the inerting fluid have a lower melting point than the cryogenic fluid(s) being transported. Similarly, if the inerting gas is at a higher pressure than the cryogenic fluid(s) being transported, in the event of a leak, the migration will occur from the inerting gas to the cryogenic fluid. This is particularly safe if the cryogenic fluid is hydrogen. If the external pipe is evacuated, the filling of the gaps with the spheres can be carried out under vacuum, or the vacuum can be pumped or topped up later at the factory or on the site where the main installation is being assembled. As with all installations requiring a high vacuum, the cleanliness of all internal components is essential, particularly the spheres, which must certainly be washed and dried before assembly.

[0008] Desiccant components may be introduced into the outer tube to remove residual moisture and outgassing products. Traditional heating techniques around 100°C to facilitate outgassing of the internal materials in the outer tube may be used, and heating temperatures may even be increased in the case of glass spheres, thereby reducing pumping times. The insulating vacuum in the inter-wall between the inner tube(s) and the outer tube may be either a sealed vacuum or a dynamic vacuum, which will require a permanent pumping unit to compensate for outgassing and micro-leaks during the operation of the installation.

[0009] A variant of the device consists in having all or part of the inner tube(s) (4) and / or the outer tube (5) corrugated or ribbed to allow their contraction under low stress and increase the flexibility of the line, particularly when operating conditions require a certain thickness of the inner tube(s) and / or the outer tube. The entire inner tube(s) and outer tube can be inserted into an insulating sheath (6) which contributes to improved insulation and mechanical protection of the system. The gap between the insulating sheath and the outer tube can be filled with an inerting fluid and / or spheres. Conversely, this gap filled with spheres can also be vacuum-sealed to further improve the overall insulation. Another, less efficient but simpler solution consists simply of fitting the polyurethane or foamglass insulating sheath (6) to the outer tube.

[0010] When the final installation is complex and requires the assembly of several devices, the assembly of the cryogenic, refrigerant, and / or heat transfer fluid transport system will be carried out using factory-prefabricated isometrics. The assembly will require the connection of several isometrics, which will be performed in situ either end-to-end with or without a ferrule, or via connecting rings. These connecting rings may be joined by welding and / or by screw assemblies with sealing gaskets. The insulation of the junctions or connecting rings will also be carried out in situ, either using traditional technology with superinsulation and vacuum sealing, or with hollow spheres according to the invention described above. This latter solution will be more productive and less expensive than a conventional superinsulated system.

[0011] The device may be equipped with a set of pumps, valves, filters, vents, probes, and sensors necessary for the operation, monitoring, and maintenance of the pipeline. Particularly when the device is used for transporting cryogenic fluids, liquid and gas separation systems to recover the evaporated portion of the fluids will be installed at regular intervals along the line. If the spheres are immersed in a circulating fluid, a filter system will prevent the spheres from escaping with the fluid.

[0012] When the gap between the inner tube(s) and the outer tube is evacuated, the pressure of the spheres or microspheres exerts a pressure on the outer tube that reduces or eliminates the stresses caused by this evacuation. The device will therefore allow the stress level of the outer tube of the pipeline to be adjusted. Similarly, during the filling of the cryogenic or refrigerant fluid, the cooling process causes the inner tube(s) to contract. This results in an increase in the volume of the space between the outer tube and the inner tube(s), and consequently a decrease in pressure within the spheres or microspheres. To compensate for this pressure loss, the device may include an expansion vessel-type system that allows for pressure regulation and compensation by adding more spheres or microspheres.

[0013] This expansion vessel or these expansion vessels also serve to cushion or compensate for any potential damage to part of the spheres or microspheres during an accidental shock or strong acceleration, or from internal or external vibrations in the pipeline. The expansion vessel is also evacuated and includes a reservoir of spheres or microspheres associated with a mechanical system for applying pressure to the spheres or microspheres, capable of transferring them to the gap between the inner tube(s) and the outer tube.

[0014] Figure 1 shows a longitudinal section of an example of a single-flow device, for example, in the context of an insulated, flexible pipeline for supplying cryogenic fuel. Liquid hydrogen at a temperature of 20 K flows inside the inner aluminum tube (1). The outer stainless steel tube (2) is enclosed by an outer polyurethane casing (6). The spheres (3) are hollow glass microspheres. The inner tube (1) is partially corrugated (4). The outer tube (2) is also partially corrugated in area (5).

[0015] Figure 2 shows the cross-sectional flow curve of an example of a three-flow device with a thermalization screen, within a liquid hydrogen supply circuit associated with a liquid helium circuit for cooling a superconducting engine. The first partially corrugated inner tube (8) contains the fuel and supplies a hydrogen fuel cell. The partially corrugated inner tube (9) contains liquid helium at a temperature of 4 K, supplied from a cryostat and destined for a superconducting engine element to be cooled. The third partially corrugated inner tube (10) is a return circuit for the helium reheated after cooling the superconducting element, for example, to a temperature of 80 K.

[0016] A flexible heat shield (11) is assembled onto the inner return tube (10). This shield includes the cooler inner tubes (8) and (9) and its purpose is to create a thermal barrier and stop radiation from the outer casing (12). The shield may be made of flexible sheets or rigid ferrules of copper, silver, aluminum, a polymer, or a textile with a reflective coating. When the shield is made of a rigid material, it may be corrugated, ribbed, or notched to add flexibility to the device.

[0017] Figure 3 presents an alternative to Figure 2, in which the liquid helium supply tube (9) and the liquid hydrogen supply tube (8) have a screen The thermal element (13), including the tube (8), is contained within the helium return tube (10), in which heated helium from the cooling circuit circulates around hollow glass spheres. The tube (10) is itself inserted into an insulating outer casing (12) containing hollow microspheres and a high vacuum.

[0018] Another variant consists of integrating two internal tubes of different diameters, for example, carrying hydrogen to power an engine, in the same pipeline. The two internal tubes are connected to the same heat shield. The smaller-diameter internal tube supplies hydrogen at idle speed and, through cooling via the heat shield, helps maintain the temperature of the hydrogen in the larger-diameter internal tube, which supplies hydrogen to the engine at high speed and load.

[0019] The high-performance, thermally efficient, insulated and flexible piping system for transporting cryogenic, refrigerant, and / or heat transfer fluids, as described above, offers numerous advantages and provides a particularly attractive alternative to traditional vacuum transfer lines. By eliminating all or part of the costly and meticulous superinsulation phases, it enables productive industrialization for the widespread adoption of cryogenic technologies and is particularly advantageous for medium to large production runs. Its deformation capabilities, flexibility, robustness, safety features, and adaptability to installation make this system of major interest for transporting cryogenic, refrigerant, and / or heat transfer fluids for installations on land, sea, underwater, air, or space vehicles.

Claims

Demands

1. Insulated and flexible piping device for the transport of cryogenic, refrigerant and / or heat transfer fluids, consisting of one or more internal tubes (1) through which one or more fluids circulate and contained in an external tube (2), the space between the internal tube(s) (1) and the external tube (2) being filled by solid or hollow spheres or microspheres (3), characterized in that the system provides at least one expansion vessel which allows the internal stress on the spheres or microspheres (3) to be adjusted and / or regulated and / or the internal or external shocks and vibrations to be dampened.

2. Device according to claim 1, characterized in that all or part of the inner tube(s) (4) and / or the outer tube (5) are corrugated or ringed.

3. Device according to claims 1 and 2, characterized in that the spheres or microspheres located in the space between the inner tube(s) (1) and the outer tube (2) are bathed in a fluid.

4. Device according to claims 1 and 2, characterized in that the space between the inner tube(s) (1) and the outer tube (2) in which the spheres or microspheres are located is placed under vacuum.

5. Device according to claims 1 to 4, characterized in that there are fixed supports holding the inner tube(s) (1) in the outer tube (2).

6. Device according to claims 1 to 5, characterized in that there are sliding supports holding the inner tube(s) (1) in the outer tube (2).

7. Device according to claims 1 and 6, characterized in that one or more internal tubes have a thermal screen.

8. Device according to claims 1 and 7, characterized in that one or more internal tubes are inserted into another internal tube of larger diameter in which a fluid circulates around spheres or microspheres.

9. Device according to claims 1 and 8, characterized in that the entire internal tube(s) and external tube can be inserted into an insulating envelope (6).

10. Device according to claim 9, characterized in that the gap between the insulating sheath and the outer tube

11. is filled with spheres or microspheres and / or placed under vacuum or conversely filled with an inerting fluid. Device according to claims 1 to 10, characterized in that the device may have a set of pumps, valves, filters, safety valves, vents, probes and sensors necessary for the operation, monitoring and maintenance of the pipeline.

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