Removable closure for cryogenic tank, cryogenic tank and aircraft

Abstract

Relates to a removable closure for a cryogenic tank, a cryogenic tank and an aircraft. In one aspect, a removable closure is provided for a cryogenic tank (10) comprising a tank interior (46) for storing a cryogenic medium and an access opening (44) in a multiple tank wall (42) comprising a tank wall vacuum insulation space (54) between an inner tank wall skin (50) and an outer tank wall skin (52). The removable closure (48) comprises an outer closure wall (2) and an inner closure wall (3), and a closure vacuum insulation volume (7) between the outer closure wall (2) and the inner closure wall (3). The removable closure (48) is configured for mounting equipment (74) required for operating the cryogenic tank (10) in a closure vacuum insulation volume (7) formed in an interior of the removable closure (48). The cryogenic tank (10) comprises a closure (10). The aircraft includes a cryogenic tank (10) having a closure (48).

Description

Technical Field

[0001] This invention relates to removable closures for cryogenic tanks, particularly for aircraft. Furthermore, this invention relates to cryogenic tanks including such closures. Additionally, this invention relates to aircraft including such cryogenic tanks or closures.

[0002] According to a preferred embodiment, the cryogenic tank is a liquid hydrogen (LH2) tank for storing liquid hydrogen. Background Technology

[0003] Regarding the technical background, the following literature was referenced:

[0004] [1]DE 10 2014 107 316 A1

[0005] [2]US 2021 / 0 078 702A1

[0006] [3]WO 2021 / 148 335A1

[0007] [4]US 2023 / 0 002 069 A1

[0008] [5]EP 4 119 834 A1

[0009] [6]EP 4 124 568 A1

[0010] [7]EP 4 124 790 A1

[0011] [8] Product brochure downloaded on May 23, 2023: Demaco-Cryogenics Johnston Coupling

[0012] [9]EP 4 279 392 A1.

[0013] [1] through [3] and [9] relate to hydrogen devices in aircraft. [4] through [7] relate to cryogenic tanks for aircraft, particularly liquid hydrogen tanks (LH2 tanks), and aircraft having such cryogenic tanks. [8] relates to a so-called Johnston coupling device for connecting cryogenic pipe sections.

[0014] Lightweight energy storage is a key challenge for next-generation aircraft. Hydrogen offers high energy density, and storage technologies (cryotherapy, compression, solid-state / absorption) are crucial. Hydrogen can be compressed and / or cooled to cryogenic temperatures to increase its volumetric and gravimetric energy density. Typically, this requires complex tank systems, which impose separate requirements on materials, design, and operating principles, such as operational safety.

[0015] Compressed and cryogenic hydrogen is the technology of choice for transportation vehicles such as cars and airplanes today. Cryogenic tanks allow for the lowest fuel volume to fuel mass ratio.

[0016] Cryogenic tanks, such as the LH2 tank, require very good thermal insulation properties. Therefore, cryogenic tanks typically have a double-walled vacuum insulation design, meaning that the cryogenic tank has double walls that include a vacuum space surrounding the interior of the tank.

[0017] Hydrogen tanks are typically completely sealed by welding. However, maintenance of such cryogenic tanks requires access to the interior. Consequently, maintaining or replacing equipment or devices inside the tank demands significant effort. As a result, the entire tank may need to be removed, for example, from the aircraft, and repairs may need to be performed outside the aircraft, requiring the tank to be cut open to allow for internal maintenance activities.

[0018] Furthermore, the vacuum surrounding the interior of the cryogenic tank for thermal insulation is a high vacuum, which is difficult to achieve. Creating such a vacuum within the walls of the cryogenic tank can take days or even weeks. Therefore, maintaining cryogenic tanks requires a significant investment of effort and results in relatively long periods of tank downtime.

[0019] In addition, cryogenic tanks typically have an equipment compartment containing tank equipment such as valves, sensors, level gauges, etc., which is necessary for handling and operating such tanks. The equipment compartment is attached to the tank or installed separately. The equipment may be partially located inside the tank, but most of it is installed separately inside the protective shell or compartment.

[0020] To limit heat ingress, the protective casing or chamber—also known as a cold box—is typically evacuated or at least filled with an inert gas. For leak prevention, valves, sensors, and connecting pipes are welded together inside the protective casing. Therefore, any maintenance of the equipment is complex.

[0021] For maintenance activities to be carried out on the protective housing or tank, it is necessary to remove the protective housing or tank from the vehicle or aircraft on which it is installed.

[0022] Therefore, in addition to the significant effort and time required to maintain the tank, even more effort and longer timeframes are needed to maintain the equipment housed within the chamber, which is essential for operating the cryogenic tank. Summary of the Invention

[0023] The purpose of this invention is to improve hydrogen tanks used in transportation vehicles, such as aircraft. In particular, the workload, time, and cost required for maintaining the tanks and tank equipment should be reduced.

[0024] According to a first aspect, the present invention provides a removable closure for a cryogenic tank, the cryogenic tank including a tank interior for storing a cryogenic medium and an access opening in multiple tank walls, the multiple tank walls including a tank wall vacuum-insulated space located between an inner tank wall skin and an outer tank wall skin, wherein the removable closure includes an outer closure wall and an inner closure wall, and a closure vacuum volume located between the outer closure wall and the inner closure wall; wherein the removable closure is configured to house equipment required for operating the cryogenic tank in the closure vacuum-insulated volume formed inside the removable closure.

[0025] The main advantages of this invention are:

[0026] a) The space required for tanks and compartments is reduced due to the use of removable closures that include vacuum-insulated volumes.

[0027] b) The amount of heat entering the cabin is reduced.

[0028] c) The risk of external hydrogen (H2) leakage is reduced.

[0029] d) The equipment becomes replaceable, for example, the equipment can be replaced by the tank closure without cutting the tank structure and breaking the tank vacuum.

[0030] e) Opening and closing the removable closure will not affect the vacuum.

[0031] Specifically, the removable closure of the cryogenic tank forms a protective shell or compartment that houses the tank equipment; that is, the compartment is incorporated into the removable tank closure.

[0032] Preferably, a removable closure is inserted into the tank. Therefore, the amount of heat entering the compartment is significantly reduced.

[0033] Preferably, when the tank is closed, the removable closure is largely located inside the tank. This significantly reduces the risk of external H2 leakage.

[0034] Preferably, the inner sealing wall and the outer sealing wall are spaced apart by a certain distance, such that when the inlet opening is closed, at least a portion of the vacuum-insulated volume of the sealing member is placed inside the cryogenic tank.

[0035] Preferably, the inner closure wall is located at the bottom of the removable closure. This creates a larger vacuum volume, which is now used to mount the equipment therein, rather than mounting the equipment in a protective shell or compartment outside the tank.

[0036] Preferably, the removable closure includes an annular wall that can form a tube, connecting the outer closure wall to the inner closure wall to form a vacuum-insulated volume portion of the closure.

[0037] Preferably, the closure flange, which can be formed as a flange ring, is attached to the ring wall for securing the removable closure to the tank flange or tank flange ring mounted on the cryogenic tank.

[0038] Preferably, one or more tubes extend through the outer closure wall into the vacuum volume of the closure.

[0039] Preferably, one or more tubes extend through the vacuum volume of the closure and through the inner closure wall.

[0040] Preferably, when the cryogenic tank is sealed, one or more tubes extend into or through the interior of the cryogenic tank.

[0041] Preferably, the removable closure includes a vacuum port for venting the vacuum-insulated volume of the closure.

[0042] Preferably, multiple layers of insulating components are assembled inside the vacuum volume portion of the sealed component.

[0043] Preferably, the closure includes or can be formed as a panel, which is formed, for example, by an outer closure wall and / or an inner closure wall. In particular, the panel is a double-walled access panel.

[0044] According to a second aspect, the present invention provides a cryogenic tank comprising multiple tank walls, an access opening in the multiple tank walls allowing access to the interior of the cryogenic tank for maintenance, repair and / or replacement services, and a removable closure for closing the access opening, wherein the multiple tank walls include an inner tank wall skin, an outer tank wall skin and a tank wall vacuum-insulated space between the inner tank wall skin and the outer tank wall skin, and wherein the removable closure is constructed according to a first aspect of the present invention.

[0045] Preferably, the entry opening in the multi-walled tank is defined by a multi-walled tank ring having an outer tank ring wall arrangement, an inner tank ring wall, and a tank ring vacuum insulation space located between the outer and inner tank ring walls.

[0046] Preferably, the ends of the multi-walled can ring are tightly sealed to form a vacuum insulation space between the outer can ring wall and the inner can ring wall.

[0047] Preferably, the outer tank annular wall arrangement includes an inner outer tank annular wall arranged inside the inner tank wall skin and an outer outer tank annular wall arranged outside the outer tank wall skin.

[0048] Preferably, the outer tank ring wall is arranged to be tightly connected to the outer tank wall skin and the inner tank wall skin, such that the tank wall vacuum insulation space and the tank ring vacuum insulation space are in fluid communication with each other and / or form a single tank wall void vacuum volume.

[0049] Preferably, the inlet opening has a can flange, and the closure has a closure flange that mates with the can flange, such that in the closed state, the closure flange is tightly connected to the can flange, particularly by means of a plurality of bolts and screws.

[0050] According to a third aspect, the present invention provides an aircraft comprising a cryogenic tank equipped with a removable closure according to a first aspect of the invention.

[0051] The features and advantages described regarding removable closures also apply to cryogenic tanks, and vice versa. Attached Figure Description

[0052] In the following, exemplary embodiments of the invention, illustrating other advantages and features, are described in detail with reference to the figures:

[0053] Figure 1 It depicts an aircraft equipped with a cryogenic tank;

[0054] Figure 2 It is a cross-sectional view taken through a portion (e.g., the top portion) of the cryogenic tank, where the inlet opening and the closure for the inlet opening are in a closed state;

[0055] Figure 3 Is it like this? Figure 2 The cross-sectional view shown indicates that the entry opening and the closure are in the open state; and

[0056] Figure 4 This is a schematic diagram of a cryogenic tank, in which the inlet opening and the sealing components are in a closed state;

[0057] Figure 5 An enlarged cross-section of the tank inlet in the open state is shown; and

[0058] Figure 6 An enlarged cross-section of the tank inlet in the closed state is shown.

[0059] In these figures, similar or identical elements and features are indicated by the same reference numerals. Detailed Implementation

[0060] Reference Figure 1 The aircraft 30 includes a fuselage 32. The aircraft 30 also includes a pair of wings 34 attached to the fuselage 32. In addition, an engine 36 is attached to each wing 34.

[0061] The aircraft 30 includes a rear section 38, which includes horizontal and vertical tail fin planes. Additionally, the aircraft 30 includes a tank assembly 40.

[0062] The tank assembly 40 includes a cryogenic tank 10, which is preferably arranged in the rear section 38. It should be noted that the cryogenic tank 10 may have different shapes and / or be located in different sections of the aircraft 30.

[0063] Tank 10 contains hydrogen fuel that can be supplied to engine 36. The hydrogen fuel can also be supplied to a fuel cell (not shown), in which hydrogen is converted into electrical energy, and then the electrical energy is supplied to engine 36. The hydrogen fuel is stored in tank 10 in the form of a cryogenic liquid, i.e., liquid hydrogen (LH2).

[0064] Reference Figures 2 to 6 The preferred embodiments of the cryogenic tank 10 and the preferred embodiments of the removable closure 48 for the cryogenic tank will be explained in more detail.

[0065] The cryogenic tank 10 includes multiple tank walls 42, an access opening 44 in the multiple tank walls 42 that allows access to the interior 46 of the cryogenic tank 10 for maintenance or repair services, and a closure 48 or cap for closing the access opening 44.

[0066] In the illustrated embodiment, the cryogenic tank 10 is a double-walled tank 10, wherein the multiple tank walls 42 include an inner tank wall skin 50, an outer tank wall skin 52, and a tank wall vacuum insulation space 54 between the inner tank wall skin 50 and the outer tank wall skin 52.

[0067] The closure 48 includes an upper closure wall or outer closure wall 2, a lower closure wall or inner closure wall 3, and a closure vacuum insulating volume portion 7 located between the outer closure wall 2 and the inner closure wall 3.

[0068] The enclosure 48 is configured to house the equipment 74 required for operating the cryogenic tank 10 in the enclosure vacuum-insulated volume 7 formed inside the enclosure 48.

[0069] In the illustrated embodiment, the inlet opening 44 is arranged in the top portion of the cryogenic tank 10. Figure 2 A cross-sectional view of the closed section, taken through the top portion, is shown. Figure 3 A cross-sectional view showing the open state is shown. Figure 4 A three-dimensional view in a closed state is shown. Figure 5 An enlarged cross-section of the tank inlet in the open state is shown, and Figure 6 An enlarged cross-section of the tank inlet in the closed state is shown.

[0070] In the illustrated embodiment, the closure 48 may form or include a panel 56, particularly a double-walled access panel, which includes an outer closure wall 2 and an inner closure wall 3, also referred to as an outer panel wall and an inner panel wall. The closure vacuum-insulated volume 7 is also referred to as a panel vacuum-insulated space.

[0071] The inner sealing wall 3 and the outer sealing wall 2 are spaced apart by a certain distance D. When the inlet opening 44 is closed by the removable closure 48, this distance D allows at least a portion of the vacuum-insulated volume 7 of the sealing member to be placed inside the interior 46 of the cryogenic vessel 10. In this way, at least a portion of the vacuum-insulated volume 7 of the sealing member is surrounded by the cryogenic medium inside the interior 46 of the cryogenic vessel 10, and is therefore completely insulated.

[0072] In the illustrated embodiment, the inner closure wall 3 is located at the bottom of the removable closure 48. This creates a very large vacuum for the device 74 used to install the cryogenic tank 10.

[0073] The removable closure 48 includes an annular wall 4 formed as a tube, which connects the outer closure wall 2 and the inner closure wall 3 to form a vacuum-insulated volume portion 7 of the closure.

[0074] The annular wall 4 is attached to the closure flange 1, which is formed as a flange ring, for securing the removable closure 48 to the tank flange 11, which is also formed as a flange ring, and the tank flange 11 is mounted at the cryogenic tank 10.

[0075] The annular wall 4 of the closure 48, the outer closure wall 2 located at the upper end of the closure 10, and the inner closure wall 3 located at the lower end of the closure 10 are welded together to form the closure vacuum insulation volume 7, which is also referred to as the panel vacuum volume or panel vacuum insulation space.

[0076] Multiple tubes 20, 22 extend into the tank 10 and are routed through the closure 48. They extend from the outside of the closure 48 through the outer closure wall 2 into the vacuum-insulated volume 7 of the closure.

[0077] An equipment actuator 73 is installed on the outside of the tank 10 and the closure 48, and the equipment actuator 73 is connected to the inside 46 of the tank 10 through pipes 20 and 22.

[0078] The tube 22 extends through the vacuum-insulated enclosed volume 7 and through the inner enclosed wall 3 into or through the interior 46 of the cryogenic tank.

[0079] The removable closure 48 also includes a vacuum port 8 for evacuating the vacuum insulating volume 7 of the closure. Air is extracted through the vacuum port 8 to create a vacuum in the vacuum insulating volume 7 formed inside the closure 48.

[0080] An insulating element formed as a multilayer insulating element (MLI) is assembled inside the vacuum insulating volume 7 of the enclosed component.

[0081] A can flange 11 is located on one side of the multi-can wall 42, which is mounted on the multi-can wall 42 and engages with a closure flange 1, also referred to as a panel flange. A seal 12 is installed between the can flange 11 and the closure flange 1. The flanges 1 and 11 are bolted together by a plurality of bolts and screw assemblies 13.

[0082] In some embodiments, the multiple can wall 42 includes a multiple can ring 64 having an outer can ring wall arrangement 14, 15, an inner can ring wall 16, and a can ring vacuum insulation space 66 between the outer can ring walls 14, 15 and the inner can ring wall 16.

[0083] In some embodiments, the outer tank annular wall arrangements 14, 15 include an inner outer tank annular wall 14 disposed inside the inner tank wall skin 50 and an outer outer tank annular wall 15 disposed outside the outer tank wall skin 52.

[0084] As in Figure 5 and Figure 6 As can be seen in the enlarged view, the multi-walled can ring 64 forms an axis connected to the can flange 11. This axis includes an inner outer can ring wall 14 (e.g., a lower outer ring made of can wall material), an outer outer can ring wall 15 (e.g., an upper outer ring made of can wall material), an inner can ring wall 16 (e.g., an inner ring made of can wall material), and an inner closure plate 17 or end plate (e.g., a lower closure plate made of can wall material for closing the inner end of the multi-walled can ring 64). The other end of the multi-walled can ring 64 is tightly closed by the can flange 11.

[0085] The surfaces of the closure annular wall 4 forming the outer tube and the inner tank annular wall 16 forming the inner tube have smooth surfaces, which allows for a tight fit, similar to the fit used in the so-called Johnston coupling device for cryogenic fluid tubes.

[0086] All tank-side components 11, 14, 15, 16, 17, 50 and 52 are welded to form a multi-walled tank 42 having an access opening 44 defined by a multi-walled tank ring 64.

[0087] A single can wall void volume 18 is formed within the multiple can walls 42. In other words, the vacuum-insulated spaces 54 and 66 between the inner can wall skin 50 and the outer can wall skin 52, and between the can ring walls 14, 15, and 16, combine to form a single can wall void volume 18. This can wall void volume 18 is also thermally insulated by a multilayer insulation (MLI – not shown in detail).

[0088] The enclosed insulating vacuum volume 7, together with the evacuated tank wall insulating spaces 54 and 66, is part of the thermal insulation of the cryogenic tank 10.

[0089] The pipes 20 and 22 extending into the cryogenic tank 10 are routed through the entry panel 56, i.e., through the closure 48 and the vacuum-insulated volume 7 formed therein. Therefore, it is not necessary to assemble double-walled sections into the pipes 20 and 22 to minimize the heat entering along the pipes 20 and 22.

[0090] Pipes 20 and 22 can also be used as structural support components, that is, pipes 20 and 22 can ensure the distance D between the outer panel wall 2 and the inner panel wall 3.

[0091] The cryogenic tank 10 for the aircraft 30 has been described above, providing a tank inlet for maintenance, inspection, and repair within the onboard tank of the aircraft 30. The access opening 44 is closed by a removable closure 48, which includes or forms a multi-wall panel 56. When the access opening 44 is closed, the multi-wall panel 56 forms a vacuum-insulated volume 7 of the tank 10, minimizing heat entering the cryogenic tank 10.

[0092] The equipment 74 for operating the cryogenic tank 10, such as pipes, sensors, level gauges, etc., is located within the vacuum-insulated volume 7 of the removable closure 48 of the cryogenic tank 10.

[0093] This invention improves the system installation on liquid hydrogen tanks. These tanks typically have an equipment compartment containing tank equipment (valves, sensors, etc.), which has traditionally been attached to or installed separately from the tank. This invention provides an improved technical solution for such a compartment. This invention is particularly applicable to hydrogen-powered aircraft.

[0094] List of reference numerals in the attached diagram:

[0095] 1. Sealing flange

[0096] 2. Upper enclosure wall / outer enclosure wall

[0097] 3. Lower closing component wall or inner closing component wall

[0098] 4. Sealing element ring wall / pipe

[0099] 7. Enclosed vacuum-insulated volumetric section

[0100] 8 Vacuum ports

[0101] 10 Cryogenic Tanks

[0102] 11 can flanges

[0103] 12 Seals

[0104] 13. Arrangement of Bolts and Screws

[0105] 14. Internal and external tank ring walls

[0106] 15. External tank ring wall

[0107] 16 Inner tank annular wall

[0108] 17 Internal enclosure panel

[0109] 18. Void volume of tank wall

[0110] 20, 22 tubes

[0111] 30 aircraft

[0112] 32 fuselage

[0113] 34 Wings

[0114] 36 Engines

[0115] 38. Rear Section

[0116] 40 tank unit

[0117] 42. Multiple tank walls (e.g., double tank walls)

[0118] 44 Enter the opening

[0119] The inside of 46 cans

[0120] 48. Enclosure

[0121] 50 Inner tank wall skin

[0122] 52 Outer tank wall skin

[0123] 54. Insulation space in tank wall

[0124] 56 panels

[0125] 64 Multi-walled tank rings

[0126] 66-tank ring vacuum insulation space

[0127] 74 Equipment

[0128] 73 Equipment Actuator

[0129] D. Distance.

Claims

1. A removable closure for a cryogenic tank (10), wherein, The cryogenic tank (10) includes: a tank interior (46) for storing cryogenic media, and an entry opening (44) in the multiple tank walls (42), the multiple tank walls (42) including a tank wall vacuum insulation space (54) located between the inner tank wall skin (50) and the outer tank wall skin (52), The removable closure (48) includes an outer closure wall (2) and an inner closure wall (3), and a closure vacuum-insulated volume portion (7) located between the outer closure wall (2) and the inner closure wall (3). The removable closure (48) is configured to house the equipment (74) required for operating the cryogenic tank (10) in the vacuum-insulated volume (7) of the closure formed inside the removable closure (48).

2. The removable closure according to claim 1, characterized in that, The inner sealing wall (3) is spaced apart from the outer sealing wall (2) by a certain distance (D), such that when the inlet opening (44) is closed, at least a portion of the vacuum insulating volume portion (7) of the sealing member is placed inside the cryogenic tank (10).

3. The removable closure according to claim 1 or 2, characterized in that, The inner closure wall (3) is located at the bottom of the removable closure (48).

4. The removable closure according to any one of the preceding claims, characterized in that, The removable closure (48) includes an annular wall (4) and a closure flange (1), the annular wall (4) connecting the outer closure wall (2) and the inner closure wall (3) to form the closure vacuum-insulated volume (7), and the closure flange (1) being attached to the annular wall (4) for securing the removable closure (48) to a tank flange (11) mounted on the cryogenic tank (10).

5. The removable closure according to any one of the preceding claims, characterized in that, One or more tubes (20, 22): Extending through the outer enclosure wall (2) into the vacuum-insulated volume (7) of the enclosure, and / or Extending through the vacuum-insulated volume portion (7) of the enclosure and the wall (3) of the inner enclosure, and / or When the cryogenic tank (10) is closed, it extends into or through the interior (46) of the cryogenic tank (10).

6. The removable closure according to any one of the preceding claims, characterized in that, Includes a vacuum port (8) for venting the vacuum-insulated volume (7) of the enclosure.

7. The removable closure according to any one of the preceding claims, wherein a multilayer insulating member is assembled inside the vacuum insulating volume (7) of the closure.

8. A cryogenic tank (10), said cryogenic tank (10) comprising: Multiple tank walls (42), Access openings (44) in the multiple tank walls (42) allow access to the interior (46) of the cryogenic tank (10) for maintenance, repair, and / or replacement services. and a removable closure (48) for closing the access opening (44), The multiple tank walls (42) include an inner tank wall skin (50), an outer tank wall skin (52), and a vacuum insulation space (54) between the inner tank wall skin (50) and the outer tank wall skin (52). The removable closure (48) is constructed according to any one of claims 1 to 7.

9. The cryogenic tank according to claim 8, characterized in that, The entry opening (44) in the multi-walled tank (42) is defined by a multi-walled tank ring (64) having an outer tank ring wall arrangement (14, 15), an inner tank ring wall (16), and a tank ring vacuum insulation space (66) located between the outer tank ring wall (14, 15) and the inner tank ring wall (16).

10. The cryogenic tank (10) according to claim 9, characterized in that, The ends of the multi-walled tank ring (64) are tightly sealed, and / or The outer tank annular wall arrangement (14, 15) includes an inner outer tank annular wall (14) disposed inside the inner tank wall skin (50) and an outer outer tank annular wall (15) disposed outside the outer tank wall skin (52); and / or The outer tank ring wall arrangement (14, 15) is tightly connected to the outer tank wall skin (52) and the inner tank wall skin (50), such that the tank wall vacuum insulation space (54) and the tank ring vacuum insulation space (66) are in fluid communication with each other and / or form a single tank wall void vacuum volume (18).

11. The cryogenic tank (10) according to any one of claims 8 to 10, characterized in that, The inlet opening (44) has a can flange (11), and the closure (48) has a closure flange (1) that mates with the can flange (11) such that, in the closed state, the closure flange (1) is tightly connected to the can flange (11), particularly by means of a plurality of bolt and screw assemblies (13).

12. An aircraft (30) comprising a cryogenic tank (10) equipped with a removable closure (48) according to any one of claims 1 to 7 and / or a cryogenic tank (10) according to any one of claims 8 to 11.

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