Cryogenic liquid storage systems

Abstract

We provide cryogenic liquid storage systems. [Solution] A cryogenic liquid storage system comprising an outer tank, an inner tank located inside the outer tank and configured to store cryogenic liquid, an isolation valve, a recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, wherein the isolation valve can be operated to isolate the recovery chamber from the inner tank, and a measuring probe movable between the inner tank and the recovery chamber.

Description

Technical Field

[0001] The present invention relates to a cryogenic liquid storage system, an aircraft, and a method for accessing a measurement probe of a cryogenic liquid storage system.

Background Art

[0002] Considering the difficulty of reaching components housed within a multi-wall storage container, it is difficult to maintain components within a cryogenic liquid storage system, particularly within a cryogenic storage tank. Accessing such components often requires draining the liquid stored within the cryogenic storage tank, removing the vacuum, and providing the user with direct access inside the tank to reach the components. This is time-consuming and labor-intensive, especially when the storage tank stores cryogenic liquids, as once the cryogenic liquid is drained, the device must be gradually warmed up to ambient temperature before accessing the required components.

Summary of the Invention

[0003] A first aspect of the present invention provides a cryogenic liquid storage system comprising an outer tank, an inner tank located inside the outer tank and configured to store cryogenic liquid, an isolation valve, a recovery chamber located outside the outer tank and fluidly connected to the inner tank via the isolation valve to allow fluid to flow from the inner tank to the recovery chamber, the isolation valve being operable to isolate the recovery chamber from the inner tank, and a measurement probe movable between the inner tank and the recovery chamber.

[0004] Providing a recovery chamber outside the outer tank provides user access to a volume fluidly connected to the inner tank without requiring direct access to the inner tank, for example, by passing through inlets and outlets of both the outer and inner tanks. Therefore, providing a measuring probe that is movable from the inner tank to the recovery chamber (and vice versa) allows for easier access to the probe and can improve, for example, the ease of maintenance of the measuring probe. Providing an isolation valve between the recovery chamber and the inner tank allows for selective prevention of fluid communication between the inner tank and the recovery chamber. In this way, the recovery chamber can be isolated from the inner tank so that it can be accessed, purged, or modified without affecting the conditions inside the inner tank.

[0005] Optionally, the measuring probe can move between the inner tank and the recovery chamber via an isolation valve.

[0006] The cryogenic liquid storage system may further include cryogenic liquid inside the inner tank.

[0007] The cryogenic liquid may consist of hydrogen, helium, or any other cryogenic liquid. The term “cryogenic liquid” is used here to refer to liquids below -150°C.

[0008] The cryogenic liquid may contain a fuel such as aircraft fuel.

[0009] The measuring probe may be at least partially immersed in a cryogenic liquid.

[0010] Providing a measuring probe immersed in the cryogenic liquid inside an inner tank may enable the measurement or monitoring of a range of parameters of the cryogenic liquid. Examples of these parameters may include the liquid level or volume, or the liquid temperature.

[0011] The measuring probe may be configured to measure the amount of cryogenic liquid inside the inner tank (e.g., liquid volume, mass, or liquid level).

[0012] Providing a measuring probe configured to measure the amount of liquid inside an inner tank may enable monitoring of the amount of liquid inside the inner tank over time. This data can then be used to determine the rate of change in the amount of cryogenic liquid inside the inner tank when it reaches a predetermined value or when the inner tank should be refilled with cryogenic liquid.

[0013] The cryogenic liquid storage system may further include a guide rail system (equipped with one or more guide rails) extending from the recovery chamber to the inner tank. The measuring probe may be coupled to the guide rail system and configured to move along the guide rail system when moving between the inner tank and the recovery chamber.

[0014] The measuring probe may be guided by and / or constrained by a guide rail device.

[0015] Optionally, the guide rail device has a gap at the location of the isolation valve.

[0016] The isolation valve may define a valve opening through which fluid flows between the recovery chamber and the inner tank, and through which a gate or other closing mechanism extends when activated to prevent the flow of fluid. Thus, the guide rail device may extend through the valve opening and therefore extend from the recovery chamber to the inner tank via the isolation valve.

[0017] The guide rail device can provide a convenient structure for defining the path that the measuring probe follows when moving between the inner tank and the recovery chamber. In this way, the guide rail device can be used to control the position of the measuring probe inside the inner tank or the recovery chamber, or its movement between them.

[0018] The first part of the guide rail system may extend downward within the inner tank. The second part of the guide rail system may extend laterally within the recovery chamber. The second part of the guide rail system may be substantially perpendicular to the first part of the guide rail system. The curved portion of the guide rail system may connect the first part of the guide rail system to the second part of the guide rail system.

[0019] Providing a first portion of the guide rail device extending downward within the inner tank may optionally allow a measuring probe to extend downward from the top of the inner tank along the guide rail device within the inner tank. This may allow the measuring probe to be used as a liquid level sensor. Providing a second portion of the guide rail device extending laterally within the recovery pipe may allow for a reduction in the height of the cryogenic liquid storage system compared, for example, with a guide rail device extending upward within the recovery chamber. A curved portion of the guide rail device may provide a path along which the measuring probe can move between the inner tank and the recovery chamber.

[0020] The isolation valve may include a housing that defines the valve opening through which the isolation valve passes, and a closing part for blocking the valve opening. The guide rail device may include a gap in which the closing part can move.

[0021] Providing an isolation valve with a movable physical closure to block the valve opening can provide a convenient method for isolating a recovery chamber from an inner tank. When the closure extends across the entire valve opening to block the fluid flow, the gap in the guide rails allows the closure to operate without being obstructed by the guide rail device.

[0022] The guide rail device may include a terminal stop within the inner tank to restrict the movement of the measuring probe along the guide rail device.

[0023] The terminal stop may provide a convenient way to limit the movement of the measurement probe beyond the target position inside the inner tank, and / or to control the tension in the probe, for example when the probe hangs downwards from the top of the inner tank by its own weight.

[0024] The guide rail device may have at least one curved portion in the recovery chamber. The guide rail device may follow a U-shaped path inside the recovery chamber.

[0025] Providing a guide rail device with a curved portion inside the recovery chamber can reduce the length of the recovery chamber required to accommodate the measurement probe when the probe is inside the recovery chamber.

[0026] The cryogenic liquid storage system may further include a tubular bellows between the inner tank and the outer tank. The bellows may fluidly connect the inner tank to the recovery chamber.

[0027] The tubular bellows may provide a convenient way to connect the inner tank and the outer tank to accommodate movement of the inner tank relative to the outer tank (e.g., due to temperature changes).

[0028] Optionally, the measurement probe further includes a chain, and the system further includes a drive mechanism such as a pinion gear arranged to engage with the chain to move the measurement probe between the inner tank and the recovery chamber. The chain may be movable between the inner tank and the recovery chamber.

[0029] Optionally, when the measurement probe is inside the inner tank, the chain extends from the recovery chamber to the inner tank via an isolation valve.

[0030] Optionally, the measurement probe includes one or more cables such as an optical fiber cable or an electrical cable. Optionally, when the measurement probe is inside the inner tank, the (or each) cable extends from the recovery chamber to the inner tank via an isolation valve.

[0031] The chain may comprise a series of flexible links, each of which is optionally rotatable relative to an adjacent link.

[0032] The chain may optionally provide a convenient component that engages with a drive mechanism (such as a pinion gear) to move the measuring probe in linear motion along a guide rail device.

[0033] The drive mechanism may include a clutch for selectively disengaging the drive mechanism from the chain.

[0034] Providing means for selectively disconnecting the drive mechanism from the chain can facilitate the optional removal of the drive mechanism and / or the chain from the recovery chamber for maintenance.

[0035] A vacuum space may be provided between the inner tank and the outer tank.

[0036] Providing a vacuum space between the inner and outer tanks can improve the thermal insulation of cryogenic liquid storage systems, and in particular, reduce heat transfer from and to the inner tank.

[0037] The recovery chamber may have an opening for connecting to a pump for purging the recovery chamber.

[0038] Purge of a recovery chamber can be defined as removing fluid from the recovery chamber. Providing means for purging a recovery chamber makes it possible to remove the fluid from the recovery chamber, for example, before opening the recovery chamber to provide access to the user.

[0039] The cryogenic liquid storage system may also be equipped with a pressure sensor inside the recovery chamber.

[0040] Providing a pressure sensor in the recovery chamber outside the outer tank may allow monitoring of the pressure in the inner tank when the inner tank and the recovery chamber are fluidly connected, without requiring direct access to the inner tank. This may improve the ease of maintenance of the pressure sensor, as it may be more easily accessible than a pressure sensor inside the inner tank.

[0041] A second aspect of the present invention provides an aircraft equipped with a cryogenic liquid storage system according to the first aspect of the present invention. The cryogenic liquid storage system may also include an aircraft fuel storage system.

[0042] A third aspect of the present invention provides a method for accessing a measuring probe in a cryogenic liquid storage system, the cryogenic liquid storage system comprising an outer tank, an inner tank inside the outer tank, a cryogenic liquid inside the inner tank, an isolation valve, a recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, and a measuring probe inside the inner tank, the method comprising the steps of retracting the measuring probe from the tank to the recovery chamber via the isolation valve, activating the isolation valve to isolate the recovery chamber from the inner tank, thereby preventing fluid from flowing from the inner tank to the recovery chamber via the isolation valve, opening the recovery chamber, and accessing the measuring probe in the opened recovery chamber.

[0043] The method may further include a step of purging the recovery chamber when an isolation valve is activated to isolate the recovery chamber from the inner tank.

[0044] Activating the isolation valve allows for purging the recovery chamber, which may enable the removal of fluid from inside the recovery chamber without affecting the condition and / or fluid of the inner tank.

[0045] A fourth aspect of the present invention provides an aircraft equipped with a cryogenic fuel storage system, the cryogenic fuel storage system comprising an outer tank, an inner tank inside the outer tank, cryogenic fuel inside the inner tank, an isolation valve, a recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, a measuring probe movable between the inner tank and the recovery chamber, comprising a chain, the measuring probe being immersed in the cryogenic fuel when inside the inner tank, and a guide rail device extending from the recovery chamber to the inner tank to which the measuring probe is movable, the guide rail device comprising a first portion inside the inner tank extending downward from the top of the inner tank and a second portion inside the recovery chamber extending substantially perpendicular to the first portion of the guide rail device. [Brief explanation of the drawing]

[0046] Embodiments of the present invention will now be described with reference to the accompanying drawings. [Figure 1] Figure 1 shows an aircraft. [Figure 2] Figure 2 shows a portion of the aircraft shown in Figure 1. [Figure 3] Figure 3 shows a cryogenic liquid storage system. [Figure 4] Figure 4 shows a portion of the cryogenic liquid storage system from Figure 3, with the probe deployed inside the inner tank. [Figure 5] Figure 5 shows a detailed view of a portion of the cryogenic liquid storage system shown in Figure 4, with the measuring probe in a deployed position inside the inner tank. [Figure 6] Figure 6 shows a portion of the cryogenic liquid storage system from Figure 3, with the measurement probe in a retracted position inside the recovery chamber. [Figure 7] Figure 7 shows a detailed view of a part of the cryogenic liquid storage system shown in Figure 6. [Figure 8a] Figure 8a shows the curved portion of the measurement probe. [Figure 8b] Figure 8b is a schematic cross-sectional view showing the connection between the chain and the guide rail device. [Figure 9]Figure 9 shows a method according to an embodiment of the present invention. [Modes for carrying out the invention]

[0047] Figure 1 shows an aircraft 10. The aircraft 10 has a fuselage 12 and fixed wings 13 and 14 on the starboard and port sides. Engines 15 are mounted on the respective wings 13 and 14. Although aircraft 10 is a typical jet passenger transport aircraft, the present invention is applicable to a wide variety of fixed-wing aircraft, including commercial, military, passenger, cargo, jet, propeller, and general aircraft, having any number of engines mounted on the wings or fuselage. The aircraft is a fixed-wing aircraft with a cantilever wing.

[0048] The aircraft 10 is equipped with a cryogenic liquid storage system 20 schematically shown in Figure 2. The liquid storage system 20 is shown within the fuselage 12 of the aircraft 10, but it will be understood that it may be housed anywhere on the aircraft 10, for example in the wings 13, 14. It will be further understood that the aircraft 10 may be equipped with any number of liquid storage systems 20, such as two separate liquid storage systems 20 housed within the fuselage 12. The liquid storage system 20 may be a cryogenic fuel tank configured to store cryogenic fuel, such as liquid hydrogen, which is supplied to the engine 15.

[0049] Figure 3 shows a schematic cross-section of the liquid storage system 20. The liquid storage system 20 comprises an outer tank 22 and an inner tank 24 supported inside the outer tank 22. The inner tank 24 may be supported using any suitable support structure (not shown), and it will be understood that the inner tank 22 is spaced apart from the outer tank 22. The inner tank 24 is configured to store cryogenic liquid 21. A vacuum space 23 between the outer tank 24 and the inner tank 22 reduces heat transfer to the inner tank 22. The outer tank 22 and the inner tank 24 may have openings (ports) (not shown) for filling the inner tank 24 with cryogenic liquid 21 and / or for removing the cryogenic liquid 21 from the inner tank 24.

[0050] The liquid storage system 20 further comprises a recovery chamber 26 outside the outer tank 22. The recovery chamber 26 may also be referred to as an external recovery chamber 26, where "external" is defined here as being outside the outer tank 22. The recovery chamber 26 may be formed as a separate component from the outer tank 22, or alternatively, it may be manufactured integrally with the outer tank 22, for example, as a "blister" on the outer surface of the outer tank 22. It may be preferable to provide the recovery chamber 26 as a separate component connected to the outer tank 22 so that a common recovery chamber 26 can be fixed within the scope of the liquid storage system 20.

[0051] The recovery chamber 26 is fluidically connected to the inner tank 24. A fluidic connection between components is defined here as a connection that allows the flow of fluid (i.e., liquid or gas) between those components. In this way, the fluid can flow between the inner tank 24 and the recovery chamber 26. In the liquid storage system 20 shown in Figure 3, the recovery chamber 26 is fluidly connected to the inner tank 24 via a tubular bellows section 30. The tubular bellows section 30 extends between the outer tank 22 and the inner tank 24 and provides a sealed passage between the recovery chamber 26 and the inner tank 24. The tubular bellows section 30 may comprise a flexible-walled pipe, such as a pipe with side walls formed of, for example, corrugated rubber material. This configuration allows the movement of the inner tank 24 relative to the outer tank 22 while maintaining a passage for the fluid to flow between the inner tank 24 and the recovery chamber 26. As a non-limiting example, the inner tank 24 may be supported by bearing components (not shown) that allow horizontal movement of the inner tank 24 relative to the outer tank 22 (i.e., left and right in the diagram of Figure 3). Such movement may be caused by expansion and / or contraction of the inner tank 24 as a result of temperature changes within the inner tank 24.

[0052] As shown in Figure 4, the recovery chamber 26 comprises a cylindrical housing 26a having a fitting 26b at one end and an isolation valve 40 at the other end. The isolation valve 40 is positioned between the inner tank 24 and the recovery chamber 26 so that fluid can flow between the inner tank 24 and the recovery chamber 26 through the isolation valve 40. The isolation valve 40 may comprise any suitable valve for selectively isolating the recovery chamber 26 from the inner tank 24, i.e., by preventing the flow of fluid through the isolation valve 40. Examples of such isolation valves 40 include gate valves, butterfly valves, or globe valves. The isolation valve 40 may comprise a housing 42, shown in Figure 7, defining a valve opening 43 through which fluid can flow. The isolation valve 40 further comprises a closure 44 (shown in Figures 6 and 7) positioned to selectively block the valve opening 43, preventing the flow of fluid through it, and thus isolating the recovery chamber 26 from the inner tank 24.

[0053] The liquid storage system 20 also includes a measuring probe 50 that can move between the inner tank 24 and the recovery chamber 26. The measuring probe 50 is configured to measure one or more parameters of the cryogenic liquid 21 in the inner tank 24, optionally. In a non-limiting example, the measuring probe 50 may include a temperature sensor configured to determine the temperature of the cryogenic liquid 21 in the inner tank 24, or a level sensor configured to determine the liquid level of the cryogenic liquid 21. The measuring probe 50 may also include one or more optical fiber cables 52 and a chain 70 carrying the optical fiber cables 52, as most clearly shown in Figure 8a. Each optical fiber cable 52 may have one or more fiber Bragg gratings and may be configured to determine the liquid level of the cryogenic liquid 21 inside the inner tank 24. The use of fiber Bragg gratings to determine the amount of cryogenic liquid in a tank of known dimensions is known in the art and will not be described in detail here. In other embodiments, the measuring probe may include different types of sensors (such as a temperature sensor) coupled to a flexible electrical cable, the flexible electrical cable extending between the inner tank 24 and the recovery chamber 26 when the measuring probe is inside the inner tank.

[0054] The measuring probe 50 may be connected to an external system (not shown) via a flexible connecting cable 54 (omitted from Figure 3 for clarity and most clearly shown in Figures 4 and 6). For example, the connecting cable 54 may comprise an extension of an optical fiber cable 52 housed in a flexible protective sheath.

[0055] The external system may include a light source for supplying light to the optical fiber cable 52, a light receiver for receiving light from the optical fiber cable 52, and a computer memory or similar for monitoring and storing parameter values ​​in real time. The measuring probe 50 may form part of the fuel quantity measuring system.

[0056] The measuring probe 50 is movable between an extended position and a retracted position. In the extended position shown in Figure 4, most or all of the measuring probe 50 is inside the inner tank 24. When cryogenic fluid 21 is present in the inner tank 24, the measuring probe 50 may be at least partially immersed in the cryogenic fluid 21. In the retracted position shown in Figure 6, the measuring probe 50 is entirely inside the recovery chamber 26, having passed through the isolation valve 40. Therefore, in the retracted position, the measuring probe 50 does not extend into the inner tank 24. When moving between the inner tank 24 and the recovery chamber 26, the measuring probe 50 may optionally move through the isolation valve 40 via the valve opening 43 described above.

[0057] The liquid storage system 20 may optionally further include guide rail devices 64-68, as shown in Figures 3 and 4, which extend from the recovery chamber 26 through the aforementioned tubular bellows section 30 and into the inner tank 24 via an isolation valve 40.

[0058] As shown in Figure 3, the guide rail device may include a first portion 64 extending vertically downward in the inner tank 24. A second portion 65 of the guide rail device extends laterally in the recovery chamber 26, as shown in Figure 4. A curved portion 68 of the guide rail device, shown in Figures 3 and 6, connects the first and second portions 64, 65.

[0059] The third portion 66 of the guide rail device extends laterally in the retrieval chamber 26, as shown in Figure 4. The curved portion 67 of the guide rail device connects the second and third portions 65, 66 of the guide rail device. The curved portion 67 of the guide rail may be removable from the second and third portions 65, 66 inside the retrieval chamber to allow for removal from the retrieval chamber together with the probe 50.

[0060] The measuring probe 50 is connected to guide rail devices 64-68 and is movable along the guide rail devices 64-68.

[0061] The guide rail arrangements 64-68 and the tubular bellows section 30 may be arranged so that the guide rail device does not come into contact with the tubular bellows section 30 and / or the inner tank 24 when the inner tank 24 moves relative to the outer tank 22 as described above. It will be understood that the guide rail device 64-68 may comprise a plurality of guide rails, for example, a pair of parallel guide rails as shown in Figures 5 and 7. The measuring probe 50 may move along the guide rail device that guides the measuring probe 50 as it moves inside and outside the inner tank 24. Thus, the guide rail device can define the path that the measuring probe 50 follows as it moves between the inner tank 24 and the recovery chamber 26. The guide rail device may include a terminal stop (not shown) inside the inner tank 24 to restrict the movement of the measuring probe 50, but it will be understood that in other embodiments the terminal stop may be omitted. The guide rail device may be firmly fixed to the inner tank 24 and / or the recovery chamber 26. In this way, the guide rail device and / or the terminal stop unit can define the target position of the measuring probe 50 inside the inner tank 24.

[0062] When the terminal stop is provided by a guide rail device, the tip 50a of the measuring probe 50 may contact the terminal stop when the measuring probe 50 is in the deployed position. The tip 50a of the measuring probe 50 is shown in Figure 6 in the retracted position inside the retrieval chamber 26.

[0063] A first section 64 of the guide rail device, which extends vertically within the inner tank 24, ensures that the measuring probe 50 is vertically oriented so that it can function accurately as a liquid level sensor. A terminal stop (not shown) is located at the lower end of the first (vertical) section 64 of the guide rail device.

[0064] The second and third sections 65, 66 of the guide rail device extend laterally within the recovery chamber 26 (in this case, horizontally, substantially perpendicular to the first section 64). This reduces the overall height of the liquid storage system 20 while allowing the measuring probe 50 to extend downward from the top of the inner tank 24. This height reduction can be particularly beneficial when the liquid storage system 20 is to be housed in an aircraft 10 with strict size constraints. The curved section 68 of the guide rail device provides a smooth path for the measuring probe 50 to follow as it moves between the inner tank 24 and the recovery chamber 26, taking into account the minimum bending radius of the cable 52.

[0065] In the example shown in Figure 4, portions 65-67 of the guide rail device in the retrieval chamber 26 form a U-shape. More generally, the guide rail device in the retrieval chamber 26 may have one or more curved portions. Providing a guide rail device that follows a curved or curved path in the retrieval chamber 26 reduces the length of the retrieval chamber 26 required to accommodate the measuring probe 50 in a retracted position, particularly when the measuring probe 50 comprises an elongated flexible component such as an optical fiber cable 52.

[0066] As is most clearly shown in Figure 8a, the measuring probe 50 includes a chain 70 for carrying optical fibers 52. The chain 70 comprises a series of links 71, each link 71 being rotatably connected to an adjacent link. Each optical fiber cable 52 passes through a pair of openings in each link 71, thereby coupling the optical fiber cable 52 to the chain 70.

[0067] Alternatively, the optical fiber cable 52 may be connected to a different type of chain, such as a corrugated flexible tube.

[0068] The chain 70 is attached to guide rail devices 64-68 such that the curved portions 67 and 68 of the guide rail devices cause the measuring probe 50 to follow a curved path when driven in and out of the recovery chamber 26.

[0069] Figure 8b is a schematic cross-sectional view showing an example of a proper connection between the chain 70 and the guide rail device 68. Each part of the guide rail device comprises a pair of U-shaped rails. Figure 8b shows the curved portion 68 of the guide rail device, but the other portions 64-67 are similar. The chain 70 is constrained between the U-shaped guide rails as shown, and as a result, the guide rail device can restrain and guide the measuring probe 50 as it moves between the inner tank 24 and the recovery chamber 26. The measuring probe 50 slides along the guide rail devices 64-68 as it moves.

[0070] The isolation valve 40 is coupled to the bellows section 30 by a fitting having a pair of windows 27a, 27b, as is most clearly shown in Figures 4 and 6. Window 27a allows the user to look inside the recovery chamber 26, for example, to confirm when the measuring probe 50 is in the retracted position within the recovery chamber 26. Window 27b allows the user to look inside the inner tank 24. For example, this could allow the user to confirm when the measuring probe 50 is fully extended within the recovery chamber 26.

[0071] The fitting 26b at the end of the recovery chamber 26 may further include an opening 28 for connecting to a pump or similar device (not shown) for purging the recovery chamber 26. Purging is defined here as removing fluid from the recovery chamber 26 while fluidically sealing it from the inner tank 24. The recovery chamber 26 may be purged before being opened. In this way, the user can remove fluid from the recovery chamber 26 before accessing the measuring probe 50 inside the recovery chamber 26. This can be particularly beneficial if the recovery chamber 26 stores cryogenic fluid.

[0072] In the example shown in Figure 3, the liquid storage system 20 further includes a pressure sensor 29 inside the recovery chamber 26. Since the recovery chamber 26 and the inner tank 24 are fluidly connected via an isolation valve 40, the pressures in the inner tank 24 and the recovery chamber 26 are equal. Therefore, placing the pressure sensor 29 inside the recovery chamber 26 provides a convenient way to monitor the pressure in the inner tank 24 without requiring direct access to the inner tank 24. This can improve the ease of maintenance of the pressure sensor 29 and / or the liquid storage system 20.

[0073] Figures 4 and 5 show an example of the measuring probe 50 in the deployed position. In the deployed position, the isolation valve 40 is open, and the tip 50a of the measuring probe 50 is inside the inner tank 24. The chain 70 extends from the recovery chamber 26 to the inner tank 24 via the isolation valve 40, with a portion of the chain 70 remaining in the recovery chamber 26 as shown in Figure 4. The connecting cable 54 extends from a connection point 55 on the mounting fixture 26b, and the connection point 55 can be connected to an external system (not shown) as described above.

[0074] Figure 5 is a cross-sectional view showing the chain 70 and optical fiber cable 52 extending to the inner tank 24 via the tubular bellows section 30. As previously mentioned in relation to Figure 3, the measuring probe follows a curved path via the curved section 68 of the guide rail device.

[0075] Figures 6 and 7 show the measuring probe 50 in the retracted position. In the retracted position, the measuring probe 50 (including its tip 50a) is completely retracted within the recovery chamber 26 and does not extend into the inner tank 24. The isolation valve 40 is closed so that the recovery chamber 26 is fluidly isolated from the inner tank 24.

[0076] As shown in Figure 7, the isolation valve 40 includes a closing portion 44 that closes one end of the recovery chamber 26. To allow the closing portion 44 to extend across the entire width of the recovery chamber 26, a gap 69 is provided in a guide rail device 65 to which the closing portion 44 can move, as is most clearly shown in Figure 7. The gap 69 may be sufficiently large so that the closing portion 44 does not come into contact with the guide rail device 65 when closed. To reduce the possibility of the chain 70 coming off the guide rail device when moving across the gap 69, the gap 69 may be smaller than the smallest link 71 of the chain 70.

[0077] The liquid storage system 20 may further include a drive mechanism 80 as shown in Figure 7. The drive mechanism 80 is arranged to engage with a chain 70 to move the measuring probe 50 between the inner tank 24 and the recovery chamber 26. In a non-limiting example, the drive mechanism 80 may include a motor 82 arranged to rotate a pinion gear 84, the pinion gear 84 being arranged to engage with a subsequent link 71 of the chain 70 to move the chain 70 when the pinion gear 84 rotates. In this way, the drive mechanism 80 can deploy and retract the measuring probe 50 by rotating the pinion gear 84 in both directions. It will be understood that alternative drive mechanisms 80, such as a linear actuator (not shown), may be used. The configuration of the motor 82 and pinion gear 84 may be preferred to provide a small device for moving the measuring probe 50. The drive mechanism 80 may further include a clutch 86 for selectively disengaging the pinion gear 84 from the chain 70. This may allow the chain 70 to be removed, for example, for maintenance purposes, from the drive mechanism 80 and optionally from the recovery chamber 26.

[0078] The optical fiber cables 52 and the chain 70 may be provided together as a pre-assembled component before being assembled in the liquid storage system 20. Figure 8a shows some examples of such pre-assembled components. The measuring probe 50 comprises three optical fiber cables 52, but it will be understood that the measuring probe 50 may comprise any number of optical fiber cables 52. Providing the measuring probe 50 as a single pre-assembled component may improve ease of maintenance, as the measuring probe 50 can be removed more easily by handling the support chain 70 rather than directly handling the optical fiber cables 52.

[0079] Figure 9 shows a method 100 for accessing the measuring probe 50 within the liquid storage system 20. In step 110, the measuring probe 50 retracts from the inner tank 24 into the recovery chamber 26. The measuring probe 50 can be moved by driving the chain 70 as previously described with reference to Figures 4-7. In step 120, the isolation valve 40 is activated to (fluidically) isolate the recovery chamber 26 from the inner tank 24. In step 130, once the recovery chamber 26 is isolated from the inner tank 24, the recovery chamber 26 is purged as described with reference to Figure 4. In some cases, it will be understood that purging the recovery chamber 26 (i.e., step 130) may be omitted. In step 140, the recovery chamber 26 is opened to provide the user with access to the measuring probe 50. The recovery chamber 26 can be opened by removing the cover 35 at the end of the fitting 26b. Finally, in step 150, the user accesses the measuring probe 50 inside the recovery chamber 26. The user can then visually inspect the measuring probe 50, repair the measuring probe 50, or remove the measuring probe 50 from the retrieval chamber 26 so that it can be repaired or replaced. For example, the measuring probe 50 (including the chain and optical fiber cable 52) and the connecting cable 54 may be removed together from the retrieval chamber 26 as a single unit.

[0080] As described above, the curved portion 67 of the guide rail device may be detachable from the second and third portions 65 and 66 of the guide rail device. This allows the measuring probe 50 and connecting cable 54 to be removed from the retrieval chamber 26 along with the curved portion 67 of the guide rail device. This allows the chain 70 to slide outside the straight portions 65 and 66 of the guide rail device that remain in the retrieval chamber 26.

[0081] A tray (not shown) is optionally provided. The measuring probe 50, connecting cable 54, and curved portion 67 are pre-assembled on the tray and then slid in and out of the recovery chamber 26 during the maintenance process shown in Figure 9.

[0082] When the new measuring probe 50 is installed in the recovery chamber 26, the recovery chamber 26 is closed, the isolation valve 40 is opened, and the new measuring probe is driven to its deployed position inside the inner tank 24.

[0083] The vacuum space 23 between the outer tank 24 and the inner tank 22 maintains a vacuum state during the process shown in Figure 9.

[0084] Where the term "or" appears, it should be interpreted as meaning "and / or" in such a way that the items mentioned are not necessarily mutually exclusive and can be used in any appropriate combination.

[0085] Although the present invention has been described above with reference to one or more preferred embodiments, it will be understood that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. The outer tank and An inner tank located inside the outer tank and configured to store cryogenic liquid, Isolation valve, A recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, wherein the isolation valve can be operated to isolate the recovery chamber from the inner tank. A cryogenic liquid storage system comprising a measuring probe movable between the inner tank and the recovery chamber.

2. The cryogenic liquid storage system according to claim 1, further comprising a cryogenic liquid inside the inner tank, wherein the measuring probe is at least partially immersed in the cryogenic liquid.

3. The cryogenic liquid storage system according to claim 2, wherein the measuring probe is configured to measure the amount of cryogenic liquid inside the inner tank.

4. The cryogenic liquid storage system according to any one of claims 1 to 3, further comprising a guide rail device extending from the recovery chamber to the inner tank, wherein the measuring probe is connected to the guide rail device and configured to move along the guide rail device when moving between the inner tank and the recovery chamber.

5. The cryogenic liquid storage system according to claim 4, wherein the first portion of the guide rail device extends downward within the inner tank, the second portion of the guide rail device extends laterally within the recovery chamber, and the curved portion of the guide rail device connects the first portion of the guide rail device to the second portion of the guide rail device.

6. The cryogenic liquid storage system according to claim 4 or 5, wherein the isolation valve comprises a housing that defines a valve opening through which the isolation valve passes and a closing portion for blocking the valve opening, and the guide rail device comprises a gap portion that allows the closing portion to move.

7. The cryogenic liquid storage system according to any one of claims 4 to 6, wherein the guide rail device has at least one curved portion within the recovery chamber.

8. The cryogenic liquid storage system according to any one of claims 1 to 7, further comprising a tubular bellows section between the inner tank and the outer tank, wherein the bellows section fluidly connects the inner tank to the recovery chamber.

9. The cryogenic liquid storage system according to any one of claims 1 to 8, wherein the measuring probe further comprises a chain, and the system further comprises a drive mechanism arranged to engage with the chain to move the measuring probe between the inner tank and the recovery chamber.

10. The cryogenic liquid storage system according to claim 9, wherein when the measuring probe is inside the inner tank, the chain extends from the recovery chamber to the inner tank via the isolation valve.

11. The cryogenic liquid storage system according to any one of claims 1 to 10, further comprising a vacuum space between the inner tank and the outer tank.

12. The cryogenic liquid storage system according to any one of claims 1 to 11, further comprising a pressure sensor inside the recovery chamber.

13. The cryogenic liquid storage system according to any one of claims 1 to 12, wherein the measuring probe comprises one or more cables, and when the measuring probe is inside the inner tank, the cables (or each cable) extend from the recovery chamber to the inner tank via the isolation valve.

14. The cryogenic liquid storage system according to any one of claims 1 to 13, wherein the measuring probe is movable between the inner tank and the recovery chamber via the isolation valve.

15. An aircraft comprising a cryogenic liquid storage system according to any one of claims 1 to 14.

16. A method for accessing a measuring probe in a cryogenic liquid storage system, the cryogenic liquid storage system comprising an outer tank, an inner tank inside the outer tank, a cryogenic liquid inside the inner tank, an isolation valve, a recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, and a measuring probe inside the inner tank, wherein the method is: The process of retracting the measuring probe from the inner tank to the recovery chamber through the isolation valve, A step of activating the isolation valve to isolate the recovery chamber from the inner tank, thereby preventing fluid from flowing from the inner tank to the recovery chamber through the isolation valve, The process of opening the aforementioned recovery chamber, A method comprising the step of accessing the measuring probe inside the open recovery chamber.

17. The method according to claim 16, further comprising the step of purging the recovery chamber when the isolation valve is activated to isolate the recovery chamber from the inner tank.

18. An aircraft equipped with a cryogenic fuel storage system, wherein the cryogenic fuel storage system is The outer tank and The inner tank inside the outer tank, The cryogenic fuel inside the inner tank, Isolation valve, A recovery chamber located outside the outer tank and fluidly connected to the inner tank to allow fluid to flow from the inner tank to the recovery chamber via the isolation valve, A measuring probe that is movable between the inner tank and the recovery chamber, comprising a chain, wherein the measuring probe is immersed in the cryogenic fuel when it is in the inner tank, A guide rail device extending from the recovery chamber to the inner tank, wherein the measuring probe is movable, The first portion inside the inner tank extending downward from the top of the inner tank, An aircraft comprising a guide rail device comprising a second part inside the recovery chamber that extends substantially perpendicularly to the first part of the guide rail device.

Images