Removable aviation liquefied gas storage unit

Abstract

The cryogenic tank system for storing gas on board an aircraft comprises an inner vessel 26 defining a liquefied gas storage chamber 28, an outer casing 27 housing the inner vessel 26, the outer casing 27 being made of a material capable of withstanding temperatures from below -60°C to at least +80°C, and an insulating chamber 29 defined between the inner vessel 26 and the outer casing 27, the helium leak rate being less than 10. -9 The device comprises an insulating chamber 29 evacuated to an airtight state of less than millibar liters per second, two connections supporting the inner container 26 and supported by the outer casing 27, at least one of which is a sliding connection, a removable collector 38 sealingly passing through the outer casing 27 and the inner container 26, and a flexible and insulating neck portion 42 forming a sealed interface between the collector 38 and the outer casing 27 and between the collector 38 and the inner container 26, respectively, the neck portion 42 being formed to surround a part of the collector 38 and passing through the insulating chamber 29 so as to enable the collector 38 to be removed regardless of the pressure in the insulating chamber 29.

Description

[Technical field]

[0001] The present invention relates to the aviation sector. [Background technology]

[0002] In the early days of the aviation industry, high-octane gasoline engines were used. After 1945, with the development of jet engines and turbines, kerosene was used. Kerosene has a higher molecular weight, higher energy density, higher efficiency, and lower flammability than gasoline. These fuels are usually stored in tanks located in the wings, at the fuselage-wing joints, or in the tail.

[0003] The drive to reduce carbon dioxide emissions has led to the development of engines with lower fuel consumption. However, as certain technologies (especially blade tip speeds) develop, the effect of reducing carbon dioxide emissions is diminishing. This break with the past is increasingly desirable.

[0004] This led to the development of gas-powered aircraft. Gases with short or no carbon chains can be burned with oxygen when necessary with little or no pollution. On the other hand, H2, O2, C1 and C2 gases are difficult to store and prone to leaks due to their small gas molecules.

[0005] On the ground, such gases are typically stored in pressurized cases (such cases have too much weight, volume, and pressure energy to be carried on an aircraft) or in welded or bonded cryogenic tanks. Cryogenic storage of such gases has a limited storage time proportional to the amount stored.

[0006] Furthermore, hydrogen, methane, ethane, ethylene, acetylene and oxygen stored in liquid form cannot be used in internal or external combustion engines or fuel cells - they require a gaseous state for ultimate consumption.

[0007] There is therefore a need to store propellant gas on-board aircraft for consumption while applying aviation maintenance know-how and avoiding the need for new standardization. Indeed, establishing new standards is a lengthy process that risks delaying the market launch of gas-powered aircraft. Learning new maintenance know-how also takes time and is costly, which may lead to resistance. Summary of the Invention

[0008] The present invention provides a spherical or elongated cryogenic tank system for storing gas on board an aircraft, the cryogenic tank system comprising an inner vessel defining a liquefied gas storage chamber, an outer casing housing the inner vessel, the outer casing being made of a material capable of withstanding temperatures from below -60°C to at least +80°C, and an insulating chamber defined between the inner vessel and the outer casing, the inner vessel having a helium leak rate of 10 -9 The tank comprises a thermally insulated chamber, which is evacuated between the inner vessel and the outer casing, so that the pressure is less than millibar liters per second, two connections supporting the inner vessel and supported by the outer casing, at least one of which is a sliding connection, a removable collector, which passes through the outer casing and the inner vessel in a sealed manner, and flexible and thermally insulating necks, which form sealed interfaces between the collector and the outer casing and between the collector and the inner vessel, respectively, and which are formed to surround a part of the collector. The neck passes through the thermally insulated chamber so as to allow the removal of the collector independently of the pressure in the thermally insulated chamber. According to the invention, the cryogenic tank can meet the requirements of aviation practice, in particular the thermal requirements, in particular with regard to the limitation of mechanical deformations and the compactness of the ducts.

[0009] In one embodiment, the cryogenic tank system includes an externally accessible, thermally insulating stopper assembly removably attached to the collector, which provides good thermal insulation.

[0010] In one embodiment, one of the connections comprises an axial recess in the outer casing, the axial recess being adapted to receive and support an axial protrusion of the inner vessel, such that the connection is adapted for possible expansion.

[0011] In one embodiment, the outer casing comprises a frame, a number of sealed panels, and pressure-resistant seals between the frame and the panels and / or between the panels, which allows for easy maintenance.

[0012] In one embodiment, the frame includes a number of ribs and spars to provide structural stiffness.

[0013] In one embodiment, the seal is housed in a groove and in its free state protrudes from the groove by a height that is less than 10% of the height of the seal, which provides a high level of leak tightness.

[0014] In one embodiment, the cryogenic tank apparatus comprises vibration isolators provided within the inner vessel, which improve the mechanical operation (particularly the stability) of the cryogenic tank apparatus.

[0015] In one embodiment, the cryogenic tank apparatus comprises stiffeners (preferably braces or tie rods) arranged within the inner vessel, which may reduce the weight of the cryogenic tank apparatus (particularly the inner vessel).

[0016] In one embodiment, the cryogenic tank apparatus comprises at least one support ring mounted between the inner vessel and the outer casing at a distance from the connection within the thermal insulation chamber to provide increased rigidity.

[0017] In one embodiment, a hydrogen absorbent material is placed within the thermal insulation chamber, which maintains a low pressure within the thermal insulation chamber.

[0018] In one embodiment, a hydrogen presence detector is provided within the insulated chamber, which allows an alarm to sound if a limit is exceeded.

[0019] In one embodiment, the assembly of the invention comprises a cryogenic tank arrangement as described above, a temporary storage tank constituting a gasification means for pressurizing the gas provided by said cryogenic tank arrangement, an upstream valve open for the flow of liquid during a filling phase into said temporary storage tank and closed outside said filling phase, a downstream valve open for the flow of gas during a discharge phase from said temporary storage tank and closed outside said discharge phase, a compressor arranged downstream of said downstream valve, and a pressure reducer arranged downstream of said downstream valve, said upstream valve and said downstream valve being closed during the gasification phase and said upstream valve and said downstream valve being arranged for on-off (all-or-nothing) control, said compressor being operated to bring the pressure in said temporary storage tank to a value lower than the value of the pressure in said cryogenic tank arrangement at the end of said discharge phase and said pressure reducer being operated to bring the pressure of the gas at its outlet to a value lower than the pressure in said temporary storage tank at the start of said discharge phase. This arrangement ensures that the volume in the temporary storage tank provides the required autonomy for the aircraft, regardless of the state of the arrangement. The temporary storage tank is provided with a gas pressure of several hundred bar and a selected gas pressure is supplied to the gas consumer. The valve is reliable. The discharge from the temporary storage tank can be made sufficient to increase the amount of gas available to the gas consumer and such that the pressure in the temporary storage tank at the end of the discharge is lower than the current pressure in the device. The filling of the temporary storage tank is made by operating the cryogenic valve under the influence of a pressure difference. The absence of a cryogenic pump reduces weight and reduces the risk of accidents.

[0020] In one embodiment, the temporary storage tank is provided for operating pressures above 500 bar.

[0021] In one embodiment, the cryogenic tank system is provided for an operating pressure of less than 8 bar.

[0022] Other features and advantages of the present invention will become apparent from the following detailed description and accompanying drawings, in which: [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic axial cross-sectional view of an apparatus according to one embodiment of the present invention; [Diagram 2] 1 is a schematic cross-sectional view of an apparatus according to one embodiment of the present invention; [Diagram 3] 1 is a schematic exploded side view of an apparatus according to one embodiment of the present invention; [Figure 4] FIG. 2 is a schematic exploded side view of an apparatus according to another embodiment of the present invention; [Diagram 5] FIG. 2 is a perspective view showing a schematic diagram of an apparatus according to another embodiment of the present invention; [Figure 6] FIG. 2 is a cross-sectional view showing a schematic view of a neck portion according to one embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view of a neck and collector according to one embodiment of the present invention. [Figure 8] FIG. 1 shows a schematic diagram of an assembly according to one embodiment of the present invention.

[0024] The accompanying drawings may serve not only to supplement the invention but also to contribute to its definition, if desired. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The aviation gas storage device is configured to be able to be mounted on an aircraft (e.g., airplane, drone, helicopter, etc.). The aviation gas storage device contains a liquid and supplies the gas. In other words, the gas is stored in a cryogenic tank in a liquid state at a very low temperature. The cryogenic tank cannot withstand high pressures, especially above 10 bar.

[0026] The gases stored are selected from hydrogen, methane, ethane, ethylene, acetylene, and oxygen.

[0027] Applicants also consider that gasification is a rapid phenomenon that occurs at high altitudes in ambient air at -55° C. For example, gaseous hydrogen at 0° C. and 1 atmosphere pressure has about 800 times lower density, i.e., about 800 times larger volume, than liquid hydrogen at -253° C.

[0028] Furthermore, aircraft maintenance regulations require that most parts of an aircraft can be removed and repaired or replaced. This allows an aircraft to land anywhere that is compatible with the weight and landing requirements of the aircraft (airfield for airplanes, airfield for helicopters) without having to have maintenance equipment specific to the aircraft model. If damage is detected, the aircraft is configured so that it can be repaired permanently or temporarily, or disassembled to replace or repair the faulty parts, according to the manufacturer's manuals and documents approved by the aviation safety authorities. It is desirable that the aircraft parts can be easily accessed by maintenance personnel. It is desirable that the parts to be replaced are configured as small as possible to facilitate handling and transportation. It is desirable that the parts to be repaired can be repaired by proven tools and methods commonly used in the aviation industry.

[0029] Aircraft are inspected, for example, daily, weekly, etc., frequently, which keeps the aircraft on the ground for a period of time that is inversely proportional to the inspection frequency.

[0030] However, gas tanks in the terrestrial industrial and space sectors are not subject to such requirements and are not specifically designed with such repairability in mind.

[0031] The applicant has identified a need for storage using aviation cryogenic tanks on board aircraft, particularly for the storage of hydrogen, methane, ethane, ethylene, acetylene or oxygen.

[0032] Applicant has identified a need for a removable aviation cryogenic tank that is inspectable and repairable according to aircraft inspection modes. Further, there is a need for a tank that has a high ratio of useful volume to external volume, a high ratio of contained gas mass to total mass, is reliable, and is safe.

[0033] As shown, the aviation gas storage device (aviation cryogenic tank) has a generally elongated shape with rounded (curved) ends. The aviation gas storage device may have an annular shape with a longitudinal axis. The aviation gas storage device comprises an outer casing and an inner vessel. The inner vessel forms a liquefied gas storage chamber. The inner vessel is housed within the outer casing. Typically, the inner vessel and the outer casing are spaced apart from each other.

[0034] In the illustrated embodiment, the aviation gas storage device has a cylindrical center and hemispherical ends, although shapes other than cylindrical, annular, and hemispherical may be manufactured.

[0035] Each cryogenic tank is insulated to contain liquid fuel or oxidizer at -253°C. Each cryogenic tank can withstand a maximum operating pressure of around 6-10 bar.

[0036] In the embodiment shown in Figures 1 to 3, the cryo-tank 2 has an elongated shape, in particular arranged along (around) a given axis. The cryo-tank 2 has dome-shaped (hemispherical) ends and a generally cylindrical central portion. Alternatively, the cryo-tank 2 may have a spherical shape.

[0037] The cryogenic tank 2 comprises an inner vessel 26 and an outer casing 27. The inner vessel 26 defines a liquefied gas storage chamber 28 for containing the loaded gas at liquefaction temperature and the evaporated gas space. The inner vessel 26 is sealed. The inner vessel 26 can withstand the liquefaction temperature (for example, -253°C for hydrogen). The outer casing 27 contains the inner vessel 26. The outer casing 27 consists of a number of removable parts to allow access to the inner vessel 26. The outer casing 27 protects the inner vessel 26 from impacts. The outer casing 27 ensures the structural strength of the aviation gas storage device. The outer casing 27 consists of a material that can withstand temperatures from below -60°C to at least +80°C.

[0038] Between the inner vessel 26 and the outer casing 27, an insulating chamber 29 is defined. Insulation within the insulating chamber 29 is ensured by reducing the pressure compared to atmospheric pressure. Furthermore, a solid insulating material may be disposed within the insulating chamber 29. Between the inner vessel 26 and the outer casing 27, a helium leak rate (measured by a helium leak test) of 10 -9 A reduced pressure insulation chamber 29 having airtightness of millibar liters / second or less is defined (formed). The airtightness of the insulation chamber 29 here includes airtightness from the inside of the inner container 26 and airtightness from the outside atmosphere.

[0039] The inner vessel 26 may be made of a welded metal alloy. Examples of metal alloys include Al-Cu-Li alloys (particularly alloys 2050 or 2099), Al-Cu alloys (particularly alloys 2219), and stainless steels (particularly SUS304, SUS304L, SUS316, and SUS316L). The inner vessel 26 has an elongated shape with two dome-shaped (hemispherical) ends that surround (sandwich) the body. The body of the inner vessel 26 may be cylindrical. The body of the inner vessel 26 may be a body of revolution.

[0040] The outer casing 27 comprises a frame 30, a number of sealable panels 31, and a number of pressure-resistant seals between the frame 30 and the panels 31 and / or between the panels 31. The panels 31 may be assembled to the frame 30 by screwing.

[0041] The frame 30 includes a number of ribs 32 and a number of spars 33. The ribs 32 may have a closed contour, for example annular. The spars 33 extend in the longitudinal direction. The spars 33 are connected to each other at both ends of the outer casing 27.

[0042] The panel 31 is made of a welded metal alloy or composite material. An example of a composite material is an epoxy resin containing carbon, Kevlar, and / or glass fibers. Examples of metal alloys include Al-Mg alloys (particularly alloy 5086), Al-Mg-Si alloys (particularly alloy 6061), and Al-Cu-Li alloys (particularly alloy 2195).

[0043] A seal is provided between the panel 31 and the frame 30. The seal may be a metal seal or may be made of a synthetic material (e.g. elastomer). In the case of a synthetic seal, a groove is made in the panel 31 or the frame 30 to accommodate the seal. In the free state, the seal protrudes from the groove by a height less than 10% of the height of the seal, where the height of the seal refers to the diameter of the O-ring.

[0044] The cryogenic tank 2 comprises two connections between the outer casing 27 and the inner vessel 26 to support the inner vessel 26. The connections are designed to have very low thermal conductivity.

[0045] At least one of the connections is a sliding connection to accommodate the difference in expansion between the outer casing 27 and the inner container 26. The two connections are supported by the outer casing 27. The first connection is located at the most distal end. The most distal connection (first connection) 34 has a central protrusion (axial protrusion) at one end of the inner container 26. The central protrusion of the inner container 26 can slide axially over a stroke of several millimeters in cooperation with an axial recess (axially recessed recess) provided in the outer casing 27 to form a housing for the central protrusion. This allows the inner container 26 to freely contract when filling with liquefied gas and expand after discharging the liquefied gas. The most distal connection (first connection) 34 is configured to have a long heat conduction path.

[0046] The second connection portion is disposed at a position spaced a predetermined distance from the end opposite to the first connection portion. The second connection portion is provided so as to surround the inner vessel 26. The second connection portion is mounted within the insulating chamber 29. The second connection portion includes a support ring 35. The support ring 35 is mounted between the inner vessel 26 and the outer casing 27. The support ring 35 is mounted within the insulating chamber 29 at a position spaced from the connection portion(s).

[0047] The support ring 35 has a plurality of outer sectors 36 that protrude radially outward. In this embodiment, the number of outer sectors 36 is three. The outer sectors 36 have an outer peripheral surface that contacts the inner peripheral surface of the outer casing 27. The outer sectors 36 occupy an angular range of approximately 15° to 40°.

[0048] The support ring 35 has a plurality of inner sectors 37 protruding radially inward. The number of inner sectors 37 is three in this embodiment. The inner sectors 37 have a concave surface that contacts the outer peripheral surface of the inner container 26. The inner sectors 37 occupy an angular range of about 15° to 40°. The outer sectors 36 and the inner sectors 37 are arranged alternately. The outer sectors 36 and the inner sectors 37 are arranged angularly spaced apart from each other. Preferably, three inner sectors 37 and three outer sectors 36 each covering an angular range of about 20° to 30° are arranged alternately, with a region without a protrusion occupying an angular range of about 40° to 30° between them. The support ring 35 is held by sufficient friction with the inner container 26 or by permanent fixation.

[0049] The support ring 35 is made of a composite material that has low thermal conductivity and high mechanical strength.

[0050] The cryogenic tank 2 includes a removable collector 38 that passes through the outer casing 27 and the inner vessel 26 in a sealed state. The collector 38 includes a straight rod 39 for extracting the liquefied gas in the inner vessel 26. The rod 39 is made of a heat insulating material. The collector 38 has a first open end inside the inner vessel 26. The collector 38 has a second open end outside the outer casing 27. The second open end is provided so as to be connectable to a duct (for example, the outlet duct 4 as shown in FIG. 6). The first open end and the second open end are connected by a port. In the installed state, the first open end is disposed near the bottom of the inner vessel 26. The first open end is a free end. This allows the collector 38 to discharge the liquefied gas. When the liquid level becomes low, the discharge of the liquefied gas is stopped. In other words, during operation, the inner vessel 26 contains a gas phase and a liquid phase. At the end of filling, the liquid phase is at a maximum and the gas phase is at a minimum. At the end of draining, the liquid phase is at a minimum or is absent and the gas phase is at a maximum. The liquid phase is drained. The draining of the liquid phase allows the duct diameter to be significantly reduced compared to the draining of the gas phase. It also improves the compactness of the components downstream of the cryogenic tank 2. The rod 39 is also used for filling with liquefied gas.

[0051] At the second open end, the collector 38 comprises a plug 41 surrounding the rod 39. The plug 41 is made of a heat insulating material. The plug 41 projects outward from the outer casing 27. The plug 41 may be provided with a gripping area for removal, for example for maintenance purposes. The outer diameter of the plug 41 is larger than the diameter of the rod 39. The plug 41 forms a sealing head that can be removed from the cryogenic tank 2.

[0052] The stopper assembly comprises a stopper plug 41 and a stopper cap 45. In the case of an airplane or drone type aircraft, the cryogenic tank 2 may be mounted with the stopper assembly facing the front of the aircraft and with the free end of the rod 39 facing the rear of the aircraft, thereby allowing a more complete filling with liquefied gas and a more complete draining of the liquefied gas, taking advantage of the typical tilt of the aircraft of several degrees. The cryogenic tank 2 may be mounted in an inclined state, in particular by means of support members having different heights in front of and behind the cryogenic tank 2.

[0053] Furthermore, the collector 38 is provided with a level gauge 40. The level gauge 40 extends along a rod 39. The level gauge 40 is connected to the outside of the tank by wired communication through a plug 41. The level gauge 40 provides as output a signal representative of the liquid level. The level gauge 40 may be capacitive. If the collector 38 has a small angle (inclination) to the horizontal, the accuracy of the level gauge is even higher. Indeed, for a constant resolution of the level gauge and the height of the inner vessel 26, the greater the length of the inner vessel 26, the greater the length of the level gauge, which improves the accuracy. For example, a level gauge at 30° to the horizontal is twice as accurate as a vertical level gauge.

[0054] The collector 38 is provided with a gas vent 53 for rapid evacuation in case of overpressure. The vent 53 also serves to vent gas to avoid overpressure during filling. The vent 53 also serves to introduce gas to repressurize, if necessary, during evacuation. The vent 53 is located in the plug 41 and is exposed in the inner vessel 26 near the plug 41. The vent 53 is provided with a liquid check valve.

[0055] The vent 53 is disposed in the plug 41 and opens into the inner vessel 26 near the plug 41. The vent 53 is thereby connected to the gaseous space (gas space) of the inner vessel 26. The vent 53 is connected to a duct penetrating the plug 41. A bypass valve having an opening pressure lower than the allowable pressure in the cryogenic tank 2 may be connected to the duct. A rupture disc having a burst pressure lower than the allowable pressure in the cryogenic tank 2 may be connected to the duct. The bypass valve and the rupture disc are installed in parallel.

[0056] The collector 38 comprises a temperature sensor arranged at the bottom inside the plug 41. The temperature sensor provides information of the temperature measured inside the inner vessel 26.

[0057] The cryogenic tank 2 comprises an insulating neck 42. The neck 42 has a hole. The neck 42 is made of, for example, a metal. The metal is selected to have low thermal conductivity, mechanical resistance, flexibility and impermeability to hydrogen. The neck 42 is welded or screwed to the inner vessel 26 in a sealed state. The neck 42 is welded or screwed to the outer casing 27 in a sealed state. The neck 42 is sufficiently flexible to accommodate the difference in expansion between the inner vessel 26 and the outer casing 27. The neck 42 comprises an outer wall portion fixed to the inner vessel 26 and the outer casing 27. The neck 42 comprises an inner wall portion spaced apart from the inner vessel 26 and the outer casing 27. The inner wall portion may be fixed to the outer wall portion at both ends of the neck 42.

[0058] The outer wall of the neck portion 42 is cylindrical. The inner wall of the neck portion 42 is tubular and bellows-like. The inner wall of the neck portion 42 may be made of a metal plate thinner than the metal plate of the outer wall of the neck portion 42 in order to enhance elastic deformation. The inner wall of the neck portion 42 may have a bellows shape that can enhance elastic deformation. By making the inner wall of the neck portion 42 bellows-like (e.g., wavy), the contact surface between the inner wall of the neck portion 42 and the plug 41 is reduced, thereby reducing thermal conductivity.

[0059] The bellows-shaped inner wall of the neck 42 is advantageously made up of two concentric sheets, which are fitted together and connected to each other at both ends. This creates a double wall, which can reduce the risk of leakage. If one of the sheets is punctured, detection can be performed by applying a gas pressure between the two sheets, which is higher than the pressure in the insulating chamber and lower than atmospheric pressure, and monitoring the change in the applied pressure. If the applied pressure decreases, this indicates a leakage from the larger of the two sheets into the insulating chamber. If the applied pressure increases, this indicates a leakage from the smaller of the two sheets into the hole in the neck 42. The neck 42 can then be replaced. Furthermore, if only one of the two sheets leaks, the insulating chamber maintains a low pressure, ensuring low heat transfer, so that the cryogenic tank 2 can be operated until the next maintenance operation. If one sheet loses its seal, the low heat transfer properties of the insulating chamber are compromised and the cryogenic tank 2 must be urgently evacuated with loss of contents.

[0060] The neck 42 forms a sealed interface between the collector 38 and the outer casing 27 and between the collector 38 and the inner vessel 26, respectively. The neck 42 maintains the airtightness between the outer casing 27 and the inner vessel 26, regardless of the position of the collector 38 or even if the collector 38 is not present. The neck 42 is sealingly fixed to a hole drilled in the outer casing 27. The neck 42 is sealingly fixed to a hole drilled in the inner vessel 26. The hole in the outer casing 27 and the hole in the inner vessel 26 are located at one rounded (hemispherical) end of the cryotank 2 near the outer periphery of the upper part of the cryotank 2. The collector 38 extends outward beyond the neck 42 at its outer end. The collector 38 extends downward into the interior of the cryotank 2 and beyond the neck 42 to the other rounded (hemispherical) end of the cryotank 2 .

[0061] The neck 42 is formed to surround a part of the collector 38. The neck 42 penetrates the insulation chamber 29 so that the collector 38 can be removed regardless of the pressure in the insulation chamber 29. The neck 42 is provided with a through hole 43. The plug 41 of the collector 38 is removably attached to the through hole 43. The contact surface between the neck 42 and the plug 41 may be provided with female annular teeth 44, which increases the length of the leakage path and makes it easier to mechanically hold the collector 38 in the neck 42. Here, the annular teeth 44 are V-shaped (chevron). The plug 41 has a smooth rotating outer surface in a free state. The plug 41 is fitted into the neck 42. There may be some play between the bellows-shaped inner wall of the neck 42 and the plug 41. A liquid deflector is provided inside the neck 42 near the liquefied gas storage chamber 28. The plug 41 is made of a heat-insulating material. The plug 41 may include a durable shell (outer shell) and a synthetic resin foam having thermal insulation properties within the shell.

[0062] In the embodiment of Figures 6 and 7, the neck 42 is welded to the inner vessel 26 around the periphery of its outer wall. The neck 42 has a flange that overlaps the flange of the inner vessel 26. The welding can be performed by an electron beam directed at the flange. The neck 42 is welded to the outer casing 27 around the periphery of its outer wall at a location spaced from the weld to the inner vessel 26. The outer wall of the neck 42 comprises two separate parts that are separated from each other. One part is connected to the inner vessel 26 and the other part is connected to the outer casing 27.

[0063] The inner wall of the neck 42 connects the two parts (parts) of the outer wall. The inner wall of the neck 42 comprises two concentric sheets with a thickness of 0.1 mm to 0.2 mm. On the outside, the neck 42 comprises a collar 54 facing the inner wall. The collar 54 hermetically connects the inner and outer walls of the neck 42. A seal 55 is fixed to the collar 54, in particular by screwing. The seal 55 contacts the plug 41 of the collector 38. There is no level gauge here.

[0064] The cryogenic tank 2 comprises a cap 45 permanently attached to the collector 38. The cap 45 is accessible from the outside. The cap 45 is fixed to the rod 39 by means of screws or bolts. The cap 45 is located outside the outer casing 27. The cap 45 is located at the outer end of the collector 38. The cap 45 is sealed.

[0065] The cryogenic tank 2 is provided for an operating pressure of less than 8 bar, in particular 6 bar.

[0066] Advantageously, the cryogenic tank 2 comprises an anti-vibration member provided inside the inner vessel 26. The anti-vibration member comprises one or more perforated panels dividing the internal volume of the inner vessel 26 into a number of regions. The openings of the perforated panel may have a surface area of ​​the order of 1% to 5% of the surface area of ​​the perforated panel. The perforated panels may be provided along the longitudinal direction or along the transverse direction. The perforated panels may reduce the speed of movement of the liquefied gas in the inner vessel 26 during acceleration (e.g. during takeoff, landing or atmospheric turbulence).

[0067] Advantageously, the cryogenic tank 2 comprises a stiffener inside the inner vessel 26. The stiffener may comprise at least one brace or tie rod connecting between opposite regions of the inner vessel 26. The stiffener allows the remaining part of the structure of the inner vessel 26 to be lighter.

[0068] The insulating chamber 29 is provided with a hydrogen absorbent material 46 (e.g., a nanoporous material) to mitigate the loss of insulation associated with pressure build-up within the insulating chamber 29 in the event of a small leak. After such a leak occurs, the outer casing 27 is removed to open the insulating chamber 29 and the hydrogen absorbent material 46 is removed to allow hydrogen to be desorbed, for example by heating.

[0069] A hydrogen presence detector 47 is provided within the insulating chamber 29, which monitors the presence of hydrogen. In case of a severe leak, a command may be given for urgent evacuation of the inner vessel 26. In case of a minor leak, maintenance work may be envisaged, which may include repairs to the inner vessel 26 to correct the leak, replacement or desorption of the hydrogen absorbent material 46 if appropriate, and evacuation of the insulating chamber 29.

[0070] In the embodiment shown in Figs. 1 to 3, the outer casing 27 comprises two separable parts 48, 49. The first part 48 constitutes one end and the body. The second part 49 constitutes the other end (opposite to the first part 48). The first part 48 and the second part 49 are connected to each other in a sealing and separable manner via two seal rings 50, 51 which provide a metal-to-metal sealing surface by engagement. The engagement may be a conical surface-to-conical surface engagement, a conical surface-to-annular surface engagement, or a flat surface-to-flat surface engagement. For example, a metal (particularly a copper alloy) or elastomer O-ring is used for the engagement, which is shrink-fitted. The engagement is ensured by axial tightening, in particular by a bolt. The seal rings 50, 51 are annular.

[0071] In the embodiment shown in Figure 4, the outer casing 27 is made up of sections, two of which are sealingly connected by sealing rings 50, 51 as previously described. The sections may be standardized to accommodate different volumes of the inner vessel 26 by using one end section, one or more central sections and one end section drilled for the neck 42. Multiple support rings 35 may be provided.

[0072] In the embodiment shown in Fig. 5, the frame 30 of the outer casing 27 includes a plurality of annular rib portions 32, a plurality of spar portions (beam portions) 33 parallel to the longitudinal axis, and a plurality of diagonally extending brace portions (bracing portions). The outer casing 27 includes a plurality of approximately triangular panels 31 attached between one rib portion 32, one spar portion 33, and one brace portion, respectively, and dome-shaped (hemispherical) panels at both ends. The triangular panels 31 are provided so that the frame 30 is visible (exposed). The dome-shaped (hemispherical) panels cover the frame 30 beyond the rib portions 32.

[0073] In the embodiment shown in Fig. 6, the distribution circuit 1 comprises a first valve 11 for each cryogenic tank 2. The first valve 11 is attached to the outlet duct 4. The first valve 11 is switchably controlled between an open position and a closed position. The intermediate positions of the first valve 11 are dynamic in the sense that the first valve 11 passes through said intermediate positions during its movement. In other words, the first valve 11 is an on-off valve. The first valve 11 may be arranged immediately downstream of the flow meter 22.

[0074] The first valves 11 can be in communication with a cryogenic distributor 5. The cryogenic distributor 5 may comprise a common pipe 6 connecting the outlets of a number of the first valves 11. The cryogenic distributor 5 is cryogenic in the sense that liquid fuel and / or oxidant pass through it.

[0075] The cryogenic distributor 5 has a plurality of outlets, specifically, for example, three outlets. A second valve 12 is attached to each outlet of the cryogenic distributor 5. The second valve 12 is switchably controlled between an open position and a closed position. The intermediate positions of the second valve 12 are dynamic in the sense that the second valve 12 passes through the intermediate positions during movement. In other words, the second valve 12 is an on-off valve. In the illustrated example, three second valves 12 are provided.

[0076] A central tank (temporary storage tank) 7 is attached downstream of each second valve 12. In this embodiment, three central tanks 7 are provided. Each central tank 7 also functions as a gasifier (gasification means). No insulation is required. Each central tank 7 receives liquid and supplies gas downstream. In each central tank 7, a pressure increase phase, i.e. a gasification phase, occurs between filling and discharging. Each central tank 7 can withstand a maximum operating pressure of about 300 to 1000 bar. Each central tank 7 is configured to operate in a temperature range of -253°C to +60°C. In some operating phases, the central tank 7 is in a gas-liquid two-phase state, and in other operating phases, it is in a gas single-phase state. A heating element (heater) 8 may be attached to each central tank 7.

[0077] A third valve 13 for supplying gas is provided downstream of each central tank 7, and a pressure reducing valve (pressure reducer) 9 is provided downstream of the third valve 13. The pressure reducing valve 9 limits the pressure for supplying gas to a consumption pressure set by the manufacturer of the gas consuming part 3. The pressure reducing valve 9 operates when the pressure in the central tank 7 is higher than the consumption pressure, and does not operate otherwise. The consumption pressure is lower than the maximum pressure of the central tank 7. The consumption pressure is independent of the maximum pressure of the cryogenic tank. The third valve 13 is an on-off valve.

[0078] Downstream of each pressure reducing valve 9, a controllable fourth valve 14 may be provided. The fourth valve 14 is an on-off valve.

[0079] The fourth valve 14 (i.e. pressure reducing valve 9) can be in communication with a manifold 10 depending on the selected option. The manifold 10 may consist of a single conduit connecting the outlets of multiple fourth valves 14 (i.e. pressure reducing valves 9). Gas flows through the manifold 10. The manifold 10 is connected downstream to supply lines (supply pipes) 23 to the gas consumers 3. Typically, one supply line 23 is provided for each gas consumer 3. Each supply line 23 may be provided with a controllable supply valve 24. The supply valves 24 are variable flow valves.

[0080] The distribution circuit 1 comprises at least one compressor 20 connected to a manifold 10. Usually, two compressors 20 are provided in parallel for redundancy. The compressors 20 are of the electric type. The compressors 20 may be provided with a controllable upstream valve. The compressors 20 feed gas into the manifold 10. In particular, in the case of one gas consumer 3, the manifold 10 consists of one pipe (conduit).

[0081] A fifth valve 15 for supplying gas is provided downstream of each central tank 7, and a second manifold is provided downstream of the fifth valve 15. The second manifold is connected to a compressor 20. The fifth valve 15 can isolate the central tank 7 from the compressor 20. The fifth valve 15 is controllable. The fifth valve 15 is an on-off valve.

[0082] The compressor 20 increases the pressure so as to supply gas at a pressure equal to the consumption pressure set by the manufacturer of the gas consumers 3, which is lower than the maximum pressure of the central tank 7. The compressor 20 takes gas from the central tank 7 at a pressure lower than the consumption pressure so that it can be supplied to the manifold 10 and the gas consumers 3. As the central tank 7 becomes more completely emptied, this results in an increase in the autonomy (supply range) provided by the gas contained in it, or a decrease in the volume of the central tank 7.

[0083] When the central tank 7 is sufficiently emptied that its internal pressure is lower than the pressure in one of the cryogenic tanks, the pressure difference allows liquid to be transferred from the cryogenic tank to the central tank 7 during subsequent filling. This draws liquid in the cryogenic tank into the central tank 7 until pressure equilibrium is reached. The elimination of the cryogenic pump is possible, thus reducing weight and energy consumption.

[0084] The distribution circuit 1 provides a combination of individual states for each cryogenic tank, for each central tank 7 and for each gas consumer 3. Several gas consumers 3 can be in operation at the same time. In normal mode, one cryogenic tank is emptied while the others are closed without being activated. However, in certain circumstances, specific modes can be provided in which several cryogenic tanks are emptied, for example to reduce their pressure. The central tank 7 has a filling mode, a gasification mode, a gas storage mode and an emptied mode.

[0085] When one cryogenic tank is being drained, the corresponding first valve 11 is open and the other first valve 11 is closed. When one gas consumer 3 is being supplied with gas, the corresponding supply valve 24 is open.

[0086] When one central tank 7 is in the filling mode, the second valve 12 connected to said central tank 7 is open and at least one first valve 11 is open. The other second valves 12 are closed except when two central tanks 7 are filled simultaneously. The third valve 13 connected to said central tank 7 is closed. The fifth valve connected to said central tank 7 is closed.

[0087] When one central tank 7 is in gasification mode, the second valve 12 connected to this central tank 7, the third valve 13 connected to this central tank 7 and the fifth valve 15 connected to this central tank 7 are closed. The gasification mode lasts for a short time, especially if the ambient atmosphere is warm and / or the central tank 7 is heated.

[0088] When one central tank 7 is in the discharge mode, the second valve 12 connected to that central tank 7 is closed. At the beginning of the discharge mode, the pressure in the central tank 7 is higher than the consumption pressure. The third valve 13 connected to that central tank 7 is open, the corresponding fourth valve 14 is open, and the fifth valve connected to the central tank 7 is closed. The gas is reduced in pressure reducing valve 9 and supplied to manifold 10 at the consumption pressure. The gas is then consumed by gas consumer 3.

[0089] At any given time, of the three central tanks 7, one central tank 7 is in the fill mode, another central tank 7 is in the gasification mode and then in the storage mode, and the remaining central tank 7 is in the discharge mode. Due to the different durations of the modes, it is also possible that two central tanks 7 are in the fill mode and the remaining central tank 7 is in the discharge mode, and it is also possible that two central tanks 7 are in the discharge mode and the remaining central tank 7 is in the fill mode. It is also possible that two central tanks 7 are in the storage mode and the remaining central tank 7 is in the discharge mode, and it is also possible that two central tanks 7 are in the discharge mode and the remaining central tank 7 is in the storage mode.

[0090] In this embodiment, a flow meter 22 is arranged at the outlet of each liquid fuel source (oxidizer source), which provides sufficiently accurate information about the amount of liquid being supplied to the central tank 7 as described above.

[0091] In this embodiment, the distribution circuit 1 comprises a control unit 25 which receives external commands, for example from an external gas consumer 3 of the aviation tank system or a central control unit of the aircraft, and liquid flow rate data from the flow meter 22. The control unit 25 generates and sends commands to the above-mentioned controllable valves (the first, second, third, fourth and fifth valves as well as the supply valve 24). The commands may be commands to "open" or to "close". The control unit 25 manages the combination of the individual states.

[0092] Alternatively, the first valve 11 may be replaced by at least one multi-way valve having multiple inlets and one outlet, in which case it is advantageous to provide a multi-way valve with a mixing position, in particular at least one position for simultaneously draining two or more cryogenic tanks to reduce pressure while preventing losses to the atmosphere.

[0093] Alternatively, the second valve 12 may be replaced by at least one multi-way valve having one inlet and multiple outlets, one for each central tank 7. The multi-way valve forms a distributor.

[0094] Alternatively, the multiple pressure reducing valves 9 may be replaced by a single pressure reducing valve 9 with which the third valve 13 can communicate. In this case, the third valve 13 may be replaced by at least one multi-way valve having multiple inlets and one outlet to the pressure reducing valve 9. The multiple fourth valves 14 are thus replaced by a single uncontrolled fourth valve 14 where appropriate.

[0095] Alternatively, the fifth valve 15 may be replaced by at least one multi-way valve having multiple inlets (one inlet for each central tank 7) and one outlet to one or more compressors 20. The multi-way valve forms a manifold 10.

[0096] Since the cryogenic tank is subject to evaporation of liquid, a gas collection circuit may be provided at the top of the cryogenic tank. The gas collection circuit may be activated when a threshold pressure is exceeded via a calibrated pressure valve. The gas collection circuit comprises a compressor for reinjecting gas downstream (e.g. between the fifth valve 15 and the compressor 20).

[0097] Optionally, additional flow meters may be placed at the inlet of each buffer tank, providing redundancy in liquid flow measurement.

[0098] The capacity of the cryogenic tank device is 10 kg to 10,000 kg in gas weight, preferably 100 kg to 10,000 kg in gas weight.

[0099] A temporary storage tank (temporary storage gasification tank, central tank) 7 is provided for pressurizing the gas supplied by the cryogenic tank system. An upstream valve 12 (second valve 12) is provided for opening for the flow of liquid during the filling phase of the temporary storage tank 7 and for closing during the discharging phase. At least one downstream valve 13, 15 (third valve 13, fifth valve 15) is provided for opening for the flow of gas during the discharging phase of the temporary storage tank 7 and for closing outside the discharging phase. The upstream valve 12 and the downstream valve 13, 15 are closed during the gasification phase. The upstream valve 12 and the downstream valve 13, 15 are on-off controlled. At least one compressor 20 is arranged downstream of the downstream valve 15. The compressor 20 is activated at the end of the discharging phase and brings the pressure in the temporary storage tank 7 to a value lower than the value of the pressure in the cryogenic tank system. A pressure reducing valve 9 is arranged downstream of the downstream valve 13, 15. The pressure reducing valve 9 is actuated at the start of the evacuation phase to reduce the pressure of the gas at the outlet to a value lower than the pressure in the temporary storage tank 7 .

[0100] The cryogenic tank device for storing gas on rail, road or sea comprises an inner vessel 26 having a spherical or elongated shape (particularly along a longitudinal axis) and defining a liquefied gas storage chamber, an outer casing 27 containing the inner vessel 26, the outer casing 27 being made up of a number of removable parts to allow access to the inner vessel 26, and an insulating chamber 29 defined between the inner vessel 26 and the outer casing 27, the helium leak rate of which is less than 10. -9A heat insulating chamber 29 is provided between the inner vessel 26 and the outer casing 27 under reduced pressure so as to have an airtightness (helium airtightness) of millibar liters / second or less, two connection parts (at least one of which is a sliding connection part) that support the inner vessel 26 and are supported by the outer casing 27, a support ring 35 is attached between the inner vessel 26 and the outer casing 27 at a position spaced apart from the connection parts in the heat insulating chamber 29, and the outer casing 27. and the inner container 26 in a sealed state; and a flexible, insulating neck portion 42 forming a sealed interface between the collector 38 and the outer casing 27 and between the collector 38 and the inner container 26, respectively, wherein the neck portion 42 is formed to surround a portion of the collector 38 and extends through the insulating chamber 29 to allow removal of the collector 38 regardless of the pressure within the insulating chamber 29.

[0101] The storage and distribution assembly comprises an inner container defining a liquefied gas storage chamber, an outer casing housing the inner container, a sealed insulated chamber defined between the inner container and the outer casing, a removable liquefied gas collector (extending across a diameter or diagonal of the inner container and having a free end adjacent a bottom of the inner container) sealingly penetrating the outer casing and the inner container, a liquefied gas duct supplied by the collector, a temporary storage tank constituting a gasification means for pressurizing the gas supplied by the cryogenic tank device, an upstream valve that is open to the flow of liquid during a filling phase into the temporary storage tank and is controlled to be closed during a discharging phase from the temporary storage tank, a downstream valve that is open to the flow of gas during a discharging phase from the temporary storage tank and is controlled to be closed outside the discharging phase, and a pressure reducing valve arranged downstream of the downstream valve, the pressure reducing valve being operated at the start of the discharging phase to reduce the pressure of the gas at the outlet to a value lower than the pressure in the temporary storage tank.

Claims

1. 1. A spherical or elongated cryogenic tank device for storing gas on board an aircraft, comprising: an inner vessel (26) defining a liquefied gas storage chamber (28); an outer casing (27) for housing the inner container (26), the outer casing (27) being made of a material capable of withstanding temperatures from below -60°C to at least +80°C, the outer casing (27) being made of several removable parts allowing access to the inner container (26); An insulating chamber (29) defined between the inner vessel (26) and the outer casing (27), the insulating chamber having a helium leak rate of 10 －９ a heat-insulating chamber (29) provided between the inner vessel (26) and the outer casing (27) under reduced pressure so as to have an airtightness of millibar liters / second or less; two connections supporting the inner container (26) and supported by the outer casing (27), at least one of which is a sliding connection; a removable collector (38) sealingly passing through said outer casing (27) and said inner vessel (26); a flexible, thermally insulating neck portion (42) forming a sealed interface between the collector (38) and the outer casing (27) and between the collector (38) and the inner vessel (26), The neck portion (42) is formed to surround a portion of the collector (38); The neck portion (42) extends through the insulating chamber (29) to allow removal of the collector (38) independent of pressure within the insulating chamber (29). Cryogenic tank equipment.

2. 2. The cryogenic tank apparatus according to claim 1, an externally accessible, thermally insulating stopper assembly removably attached to said collector (38); A cryogenic tank device characterized by:

3. 3. The cryogenic tank apparatus according to claim 1, One of the connection parts comprises an axial recess provided in the outer casing (27), The axial recess is configured to receive and support an axial protrusion of the inner container (26). A cryogenic tank device characterized by:

4. In the cryogenic tank apparatus according to any one of claims 1 to 3, The outer casing (27) is A frame (30); A plurality of sealed panels (31); and a pressure-resistant seal between the frame (30) and the panel (31) and / or between the panels (31). A cryogenic tank device characterized by:

5. 5. The cryogenic tank apparatus according to claim 4, The frame (30) comprises a plurality of rib portions (32) and a plurality of spar portions (33). A cryogenic tank device characterized by:

6. The cryogenic tank apparatus according to claim 4 or 5, The seal is received in a groove and, in a free state, protrudes from the groove by a height that is less than 10% of the height of the seal. A cryogenic tank device characterized by:

7. 7. The cryogenic tank system according to claim 1, a vibration isolating member provided within the inner vessel (26); and a reinforcing member, preferably a brace or a tie rod, provided within the inner vessel (26). A cryogenic tank device characterized by:

8. The cryogenic tank system according to any one of claims 1 to 7, at least one support ring (35) mounted between the inner vessel (26) and the outer casing (27) at a distance from the connection within the insulating chamber (29); A cryogenic tank device characterized by:

9. 9. The cryogenic tank system according to claim 1, A hydrogen absorbent is disposed within the thermal insulation chamber (29); A hydrogen presence detector is provided within the thermal insulation chamber (29). A cryogenic tank device characterized by:

10. 1. An assembly comprising: A cryogenic tank device according to any one of claims 1 to 9; a temporary storage tank (7) constituting a gasification means for pressurizing the gas supplied by the cryogenic tank device; an upstream valve (12) which is open to the flow of liquid during the filling stage of the temporary storage tank (7) and which is closed outside said filling stage; a downstream valve (13, 15) open to the flow of gas during the discharge phase from said temporary storage tank (7) and closed outside said discharge phase; a compressor (20) disposed downstream of the downstream valve (15); a pressure reducer (9) disposed downstream of the downstream valve (15), the upstream valve (12) and the downstream valves (13, 15) are closed during the gasification stage; The upstream valve (12) and the downstream valve (13, 15) are configured to be on / off controlled, said compressor (20) being operated so as to bring the pressure in said temporary storage tank (7) to a value lower than the value of the pressure in said cryogenic tank arrangement at the end of said discharge phase; the pressure reducer (9) is operated at the start of the discharge phase to bring the pressure of the gas at the outlet to a value lower than the pressure in the temporary storage tank (7); assembly.

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