TANK

Description

[0001] The invention relates to a tank for storing a cryogenic fluid.

[0002] For storing cryogenic fluids, such as liquefied natural gas, closed flat-bottom tanks are known. These tanks comprise an outer tank and an inner tank located within the outer tank. Thermal insulation can be provided between the outer tank and the inner tank. This thermal insulation can also be arranged, in particular, between a bottom of the inner tank and a bottom of the outer tank. If the outer tank is made of concrete, a vapor barrier, a so-called liner, can be provided on the inside of the outer tank. This liner ensures the gas-tightness of the outer tank. The liner can comprise a steel membrane.In order to prevent the cryogenic fluid from penetrating the thermal insulation arranged between the bottom of the inner tank and the outer tank or from penetrating to the bottom of the outer tank in the event of a leak of the cryogenic fluid from the inner tank, the thermal insulation can also be protected with a steel membrane, in particular with a so-called second bottom. This second bottom is also made of interconnected steel plates. In the event of a leak of the cryogenic fluid from the inner tank, the second bottom prevents the cryogenic fluid from penetrating the thermal insulation, reaching the bottom of the outer tank, and thus exposing the tank's foundation to undesirable cryogenic temperatures. This prevents stresses from arising in the foundation as a result of temperature differences, which could lead to damage to the foundation.

[0003] Against this background, the object of the present invention is to provide an improved tank for storing a cryogenic fluid.

[0004] Accordingly, a tank for storing a cryogenic fluid, in particular for storing liquefied natural gas, is proposed. The tank comprises an outer tank, an inner tank arranged within the outer tank, floor insulation arranged between an outer tank floor of the outer tank and an inner tank floor of the inner tank, a liquid-tight first film arranged between the outer tank floor and the inner tank floor, and a gas-tight second film arranged between the first film and the outer tank floor. The outer tank floor and an outer tank wall are made of concrete, and the inner tank is made of a metal material.

[0005] The first foil reliably prevents the tank foundation from being exposed to excessively low temperatures, as this prevents the liquid phase of the cryogenic fluid from penetrating the floor insulation. By using foils and not a rigid steel membrane, only minimal forces are exerted on the outer tank wall, even when the second foil is bonded to the outer tank wall. Compared to a second bottom made of steel plates as described above, the first foil can be installed much more quickly and requires less labor. This significantly reduces installation costs. Material costs are also significantly reduced. Installation of the foils is further simplified by the fact that they can be laid as individual foil strips that are bonded together after installation. Complex pre-assembly of the foils is not required.The layout of the film strips and the installation direction and sequence can be individually selected depending on local conditions.

[0006] The first film can be referred to as the second bottom. The second film can be a liner lining the inside of the outer tank. In particular, the first film is designed to prevent fluid escaping from the inner tank from penetrating or seeping into the floor insulation, thereby inducing stresses in the tank's foundation due to temperature differences. In this context, a "film" is understood to be a flexible or elastically deformable component of low thickness, in contrast to a steel membrane. Due to their low thickness, the films are very flexible and can be folded, bent, or deformed without noticeable effort. This enables easy installation of the films. According to the invention, the films are elastically deformable.

[0007] The first film is preferably liquid-tight and gas-permeable. Alternatively, the first film can also be gas-tight. The second film is gas-tight and liquid-tight. The first film and the second film can be made of the same material. The gas-tightness of the material of the first film and the second film results in particular from a metal component, in particular from a metal layer, which the first film and the second film have. Since the first film is not necessarily gas-tight, it does not necessarily require a metal component. Due to the required gas-tightness of the second film, it preferably always comprises a metal component. In particular when the same material is used for the first film and the second film, the first film therefore preferably has a liquid-tight and gas-permeable or non-gas-tight construction or design.Accordingly, the second film has a liquid-tight and gas-impermeable or gas-tight design or construction.

[0008] The cryogenic fluid is preferably liquefied natural gas. However, the cryogenic fluid can also be liquid ethylene or ethane (boiling point at ambient pressure 169.43 K = -103.72 °C), liquid ethane (boiling point at ambient pressure 184.1 K = -88.9 °C), or liquid propane (boiling point at ambient pressure 231.15 K = -42.1 °C). The cryogenic fluid can have a gaseous state and a liquid state and can be converted from the liquid state to the gaseous state and vice versa. The states of matter can also be referred to as phases. The cryogenic fluid can also be referred to as cryogenic gas or liquefied cryogenic gas. The tank is particularly designed to store the cryogenic fluid in its liquid state. When the cryogenic fluid changes from the liquid state to the gaseous state, this can be referred to as boil-off gas.This boil-off gas can be released using a blow-off valve, for example.

[0009] The outer tank preferably comprises the outer tank bottom, the aforementioned outer tank wall connected to the outer tank bottom, which is cylindrical and / or rotationally symmetrical to a central or symmetry axis, and an outer tank roof. The outer tank roof is preferably dome-shaped and curves outward.

[0010] The inner tank is arranged entirely within the outer tank. In addition to the inner tank base, the inner tank comprises an inner tank wall, which is also preferably cylindrical and rotationally symmetrical to the axis of symmetry. The outer tank and the inner tank are preferably arranged concentrically to one another with respect to the axis of symmetry. The inner tank and the outer tank can also be cuboid or cube-shaped. The inner tank is preferably designed as a cup that is open at the top. This means that the inner tank is not fluid-tight. The inner tank can be covered with a heat-insulating cover that is supported by a supporting structure that can be suspended from the outer tank roof by means of rods or struts. Alternatively, the inner tank can also be closed with a domed roof. When the cryogenic fluid is stored, the cryogenic fluid contacts the inner tank base and the inner tank wall.

[0011] The inner tank is preferably designed to be self-supporting. This means that the inner tank wall is constructed in such a way that it completely supports its own weight and the weight of the stored cryogenic fluid. In other words, this means that no tank component laterally touching the inner tank wall from the inside or outside bears the load of the inner tank wall or the cryogenic fluid.

[0012] The wall thickness of the inner tank wall, and preferably of the inner tank bottom, is preferably at least 2 mm, preferably at least 4 mm, and particularly preferably at least 6 mm. The wall thickness of the inner tank wall, and preferably of the inner tank bottom, is preferably up to 50 mm, more preferably up to 40 mm, and particularly preferably up to 30 mm.

[0013] According to one embodiment, the foils comprise a metal, in particular aluminum.

[0014] The films can be made of the same material or of different materials. In particular, the films can be or comprise metal foils, in particular aluminum foils. For example, the films can each have a multi-layer structure, wherein one layer can be a metal foil. The metal foil can also be referred to as the metal core, in particular as the aluminum core, of the respective film. However, the films can also each be a metallized, in particular a metal-deposited, plastic film. By using a metal, a particularly good diffusion barrier effect can be achieved. Other suitable metals can also be used instead of aluminum. For example, the first film and the second film each have an aluminum layer with a thickness of at least 0.05 mm, in order to be considered an impermeable material with a water vapor diffusion equivalent air layer thickness of greater than 1500 m.Alternatively, the first film can also be metal-free, since gas-tightness is not required for the first film. The films can be compound films, meaning they can be made of a multilayer composite material.

[0015] According to a further embodiment, the films are fiber-reinforced, in particular glass fiber-reinforced.

[0016] The films can also be carbon fiber reinforced, aramid fiber reinforced, or similar materials. This makes the films highly resilient.

[0017] According to a further embodiment, the second film is arranged between the floor insulation and the outer tank floor.

[0018] In particular, the second film rests on the outer tank floor. According to the invention, the second film is integrally connected to an outer tank wall of the outer tank, in particular glued thereto.

[0019] In bonded joints, the joining partners are held together by atomic or molecular forces. Bonded joints are non-detachable connections that can only be separated by destroying the connecting elements and / or joining partners.

[0020] According to a further embodiment, the second film completely covers the outer tank wall.

[0021] Preferably, the second film completely covers the inside of the outer tank wall, i.e., the area facing the inner tank. The second film can line the entire outer tank on the inside, particularly if the entire outer tank, including the outer tank roof, is made of concrete. This ensures the gas-tightness of the outer tank. If the outer tank is partially made of steel, completely covering the outer tank with the second film in the areas of the outer tank made of steel is unnecessary.

[0022] According to a further embodiment, the first film is arranged at least in sections within the floor insulation.

[0023] The first film can thus pass through the floor insulation. The first film can also cover the floor insulation on top.

[0024] According to a further embodiment, the floor insulation comprises a pressure-resistant insulation layer, in particular a foam glass block layer, a perlite concrete layer, a wood layer or a reinforced polyurethane layer, wherein the first film is arranged between the insulation layer and the inner tank floor.

[0025] The number of insulation layers is optional. The insulation layer is preferably constructed from a large number of foam glass blocks. Foam glass is also referred to as cellular glass or foam glass.

[0026] According to a further embodiment, the floor insulation has several insulation layers between which the first film is arranged.

[0027] The number of insulation layers is optional. For example, two or three such insulation layers are provided. The first film can run between two adjacent insulation layers.

[0028] According to a further embodiment, the floor insulation comprises a load distribution plate, wherein the load distribution plate is arranged between the inner tank floor and the insulation layer, and wherein the first film is arranged between the load distribution plate and the insulation layer.

[0029] The first foil can also be placed on the load distribution plate. The load distribution plate can be made of concrete and / or wood, for example. The load distribution plate can comprise mineral and non-mineral materials. The load distribution plate is installed directly below the inner tank floor and distributes the inner tank's load evenly across the floor insulation.

[0030] For example, the load distribution plate is a cast concrete slab. The load distribution plate can also be annular, so that it is positioned only below the inner tank wall and supports it.

[0031] According to a further embodiment, the floor insulation has a leveling layer, wherein the leveling layer is arranged between the outer tank floor and the insulation layer.

[0032] The floor insulation may comprise a first leveling layer disposed between the outer tank floor and the insulation layer, and a second leveling layer disposed between the insulation layer and the load distribution plate. The leveling layers may be cast concrete slabs. The load distribution plate may also have a ring shape, in which case the second leveling layer may be located within the ring shape.

[0033] According to a further embodiment, the second film is arranged between the outer tank bottom and the compensation layer.

[0034] In particular, the second film is arranged between the outer tank floor and the first leveling layer. The second film then preferably rests on the outer tank floor.

[0035] According to a further embodiment, the floor insulation has a cylindrical casing which is arranged between the outer tank and the inner tank, wherein the first film is provided on the inside and the second film is provided on the outside of the casing.

[0036] The jacket can also be referred to as thermal corner protection. The jacket is preferably also constructed from a plurality of foam glass blocks and can be connected to the insulation layer. "Inside" here means facing the inner tank, and "outside" here means facing the outer tank. Preferably, the first film is provided between the inner tank and the jacket, and the second film is provided between the jacket and the outer tank. The films can be bonded to the jacket.

[0037] The second film preferably covers the outer tank wall completely.

[0038] According to a further embodiment, the first film is integrally connected to the second film.

[0039] The first film is preferably glued or welded to the second film. Each film can have a plurality of film webs that are integrally bonded to one another. The first film and the second film can enclose the casing, the insulation layer, and the two leveling layers in a bag-like manner. This means that the floor insulation is, in particular, partially positioned within the films, so that the films preferably enclose the floor insulation at least in sections. The first film and the second film are integrally bonded to one another at a connecting section, in particular welded or glued to one another.

[0040] The outer tank roof can be made of concrete or steel. For example, the outer tank floor and wall can be made of concrete, and the outer tank roof can be made of steel. Alternatively, the outer tank floor, wall, and roof can be made of concrete. For example, the outer tank can be a cast concrete component in which the outer tank floor, wall, and roof are connected to one another in one piece, in particular as a single piece. The inner tank is preferably made of steel. However, the inner tank can also be made of aluminum. The tank can also be referred to as a concrete-metal tank, in particular as a concrete-steel tank.

[0041] Further possible implementations of the tank also include combinations of features or embodiments described above or below with regard to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the tank.

[0042] Further advantageous embodiments of the tank are the subject of the dependent claims and the exemplary embodiments of the tank described below. The tank is explained in more detail below using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a schematic sectional view of an embodiment of a tank for storing a cryogenic fluid; and Fig. 2 shows the detailed view II according to Fig. 1 .

[0043] In the figures, identical or functionally equivalent elements are provided with the same reference symbols unless otherwise stated.

[0044] The Fig. 1 shows a highly simplified schematic sectional view of an embodiment of a tank 1 for storing a cryogenic fluid 2. The cryogenic fluid 2 is, in particular, a cryogenic or cryogenic liquefied gas. Examples of such cryogenic fluids are liquefied natural gas, liquid ethene or ethylene (boiling point at ambient pressure 169.43 K = -103.72 °C), liquid ethane (boiling point at ambient pressure 184.1 K = -88.9 °C), or liquid propane (boiling point at ambient pressure 231.15 K = -42.1 °C).

[0045] Preferably, however, the tank 1 is suitable for storing liquefied natural gas (LNG). The cryogenic fluid 2 can have a liquid state or a liquid phase and a gaseous state or a gaseous phase, or can be transferred from the liquid phase to the gaseous phase and vice versa. The cryogenic fluid 2 is stored in its liquid phase in the tank 1. However, the cryogenic fluid 2 can partially evaporate and transition to the gaseous phase. The evaporated cryogenic fluid 2 can be referred to as boil-off gas.

[0046] The tank 1 has a slab-shaped foundation 3. The foundation 3 can be anchored directly in the ground 4. The foundation 3 can also have a plurality of supports or posts, so that the foundation 3 or the tank 1 is elevated and placed at a distance from the ground 4. The foundation 3 can be made of concrete, for example. For example, the foundation 3 can be a cast circular concrete slab. However, the foundation 3 can also have any other geometry. The tank 1 comprises a central or symmetry axis M. The foundation 3 can be constructed rotationally symmetrically to the symmetry axis M.

[0047] The tank 1 further comprises an outer tank 5 arranged on the foundation 3. The outer tank 5 has an outer tank wall 6. The outer tank wall 6 can also be referred to as an outer tank shell. The outer tank wall 6 can be circular-cylindrical in shape. In particular, the outer tank wall 6 can be constructed rotationally symmetrically to the axis of symmetry M of the tank 1. The outer tank 5 can also be referred to as an outer container.

[0048] The outer tank 5 has an outer tank base 7, which can be formed in one piece, in particular made of a single material, with the outer tank wall 6. The outer tank base 7 is placed on the foundation 3. The outer tank base 7 and the outer tank wall 6 are made of concrete. The outer tank wall 6 and the outer tank base 7 can be cast in one piece. The outer tank base 7 and the outer tank wall 6 can be designed in the form of an upwardly open cup, which can be referred to as an outer cup. In a preferred embodiment, the foundation 3, the outer tank base 7, and the outer tank wall 6 can be cast in one piece.

[0049] The outer tank 5 further comprises an outwardly curved, dome-shaped outer tank roof 8. For example, the outer tank base 7 and the outer tank wall 6 can be made of concrete, and the dome-shaped outer tank roof 8 can be made of steel. If the outer tank roof 8 is also made of steel, the outer tank roof 8 can be mounted on the outer tank wall 6. Alternatively, the outer tank base 7, the outer tank wall 6, and the outer tank roof 8 can be made of concrete. The outer tank base 7, the outer tank wall 6, and the outer tank roof 8 can be cast monolithically, i.e., in one piece, from concrete.

[0050] The tank 1 further comprises an inner tank 9 arranged within the outer tank 5. The inner tank 9 is preferably made of a steel material. The inner tank 9 is designed in the shape of a cup or closed with a dome-shaped inner tank roof. The inner tank 9 comprises a circular-cylindrical inner tank wall 10 and an inner tank base 11. The inner tank wall 10 can also be referred to as an inner tank shell. The inner tank 9, like the outer tank 5, is preferably constructed rotationally symmetrically with respect to the axis of symmetry M. The inner tank 9 can also be referred to as an inner container or inner cup. The inner tank 9 is positioned within the outer tank 5 and coaxially with the axis of symmetry M. During storage of the cryogenic fluid 2, the cryogenic fluid 2 contacts the inner tank base 11 and the inner tank wall 10.

[0051] The cup-shaped inner tank 9 is covered with a cover 12 suspended from the outer tank roof 8 of the outer tank 5. The cover 12 is not fluid-tightly connected to the inner tank 9, so that the aforementioned boil-off gas, i.e., cryogenic fluid 2 that has transitioned from the liquid state to the gaseous state, can escape from the cup-shaped inner tank 9.

[0052] The cover 12 is suspended from the outer tank roof 8 by means of metallic rods or struts 13. The cover 12 is further thermally insulated upwards or toward the outer tank 5, for example, with block-shaped insulation elements 14. The insulation elements 14 can be referred to as insulation blocks, insulation mats, or insulation bags, or can be designed as such. For example, the insulation elements 14 can be made of a foamed plastic material, such as polyurethane, polystyrene, or the like. Furthermore, the insulation elements 14 can be made of mineral wool, such as slag wool, glass wool, or rock wool. The insulation elements 14 can comprise mineral and / or non-mineral materials.

[0053] A floor insulation 15 is provided between the inner tank floor 11 of the inner tank 9 and the outer tank floor 7 of the outer tank 5. The floor insulation 15 can, for example, be partially made of foam glass. Foam glass can also be referred to as foam glass or cellular glass. Furthermore, the floor insulation 15 can be constructed from individual block-shaped elements, in particular from foam glass blocks. The floor insulation 15 can also be made at least partially of concrete. The floor insulation 15 is a load-bearing insulating component and supports the inner tank 9.

[0054] A circumferential gap 16 is provided between the outer tank wall 6 and the inner tank wall 10. The gap 16 can be at least partially filled with an insulating material, such as perlite or mineral wool. The floor insulation 15 can be arranged at least partially in the gap 16, i.e., between the inner tank wall 10 and the outer tank wall 6.

[0055] The Fig. 2shows an enlarged section of the tank 1 according to the detailed view II of the Fig. 1 . In the embodiment of the tank 1 according to the Fig. 1 and 2 The outer tank wall 6 and the outer tank bottom 7 are manufactured as a one-piece, in particular a one-piece concrete component. Fig. 2 As shown, the floor insulation 15 is arranged at least partially between the outer tank floor 7 and the inner tank floor 11. However, as previously mentioned, the floor insulation 15 can also be arranged partially in the gap 16.

[0056] The floor insulation 15 preferably comprises several pressure-resistant insulation layers 17, 18, in particular foam glass block layers, of which Fig. 2However, only two are shown. The number of insulation layers 17, 18 is arbitrary. Each insulation layer 17, 18 can be constructed from a plurality of foam glass blocks 19. In addition to foam glass blocks 19, the insulation layers 17, 18 can also comprise perlite concrete, wood, reinforced polyurethane, or other suitable insulation materials.

[0057] A first leveling layer 20 is provided between a lowest or lower insulation layer 18 and the outer tank floor 7. The first leveling layer 20 can be a cast concrete slab. A second leveling layer 21 can be provided above a top or upper insulation layer 17 and below the inner tank floor 11. The second leveling layer 21 can also be a cast concrete slab. The insulation layers 17, 18 are thus arranged between the leveling layers 20, 21. Only one such leveling layer 20, 21 can also be provided. The leveling layers 20, 21 are preferably part of the floor insulation 15.

[0058] Between the second leveling layer 21 and the inner tank bottom 11, a load distribution plate 22 is also provided. The load distribution plate 22 can, for example, also be made of concrete or wood. The load distribution plate 22 can comprise mineral and / or non-mineral materials. The inner tank 9 is supported on the load distribution plate 22. The load distribution plate 22 can also, but does not have to, be part of the floor insulation 15. Furthermore, the floor insulation 15 comprises a cylindrical casing 23, which is arranged in the gap 16. The casing 23 can be constructed rotationally symmetrically to the axis of symmetry M. The casing 23 thus runs completely around the inner tank 9, in particular around the inner tank wall 10. The casing 23 is also constructed from foam glass blocks 19 and can, as in the Fig. 2shown, be connected to the insulating layers 17, 18. The jacket 23 is arranged in particular between the inner tank wall 10 and the outer tank wall 6. The jacket 23 can be supported on the outer tank wall 6. The jacket 23 can also be referred to as thermal corner protection or thermal corner protection, since the jacket 23 thermally insulates a transition or corner between the outer tank base 7 and the outer tank wall 6.

[0059] The tank 1 further comprises a first film 24 which is in the Fig. 2 is shown with a dotted line. The first slide 24 is in the orientation of the Fig. 2positioned below the inner tank bottom 11. The first film 24 can also be referred to as the second bottom or second bottom of the tank 1. Accordingly, the inner tank bottom 11 is then a first bottom or first bottom of the tank 1. The first film 24 is arranged in particular between the outer tank bottom 7 and the inner tank bottom 11. The first film 24 covers the bottom insulation 15 upwards, i.e., in the direction of the inner tank 9. The first film 24 fulfills the function of a second bottom as explained at the beginning and can therefore also be referred to as such. Unlike known second bottoms, however, the first film 24 is not made of steel plates. The first film 24 is preferably part of the bottom insulation 15. However, the first film 24 does not have to be part of the bottom insulation 15.

[0060] The first film 24 is liquid-tight, but not necessarily gas-tight. As already explained in the introduction, the first film 24 preferably has a liquid-tight and gas-permeable or non-gas-tight construction or design. For example, the first film 24 has an aluminum layer with a thickness of at least 0.05 mm in order to represent an impermeable material with a water vapor diffusion-equivalent air layer thickness greater than 1500 m. If the first film 24 represents an impermeable material with a water vapor diffusion-equivalent air layer thickness greater than 1500 m (this applies, for example, to an aluminum layer with a thickness of 0.05 mm), the first film 24 can be considered gas-tight. This is not required for liquid-tightness. This means that the first film 24, which is necessarily only liquid-tight, can also be metal-free.

[0061] Due to its small thickness, the first film 24 is very flexible and can be folded, bent, or deformed without any noticeable effort. The first film 24 can be or comprise a metal foil, for example, an aluminum foil, or a metal-coated plastic film, for example, an aluminum-coated plastic film. The first film 24 is preferably fiber-reinforced, in particular glass-fiber reinforced. However, the first film 24 can also be carbon-fiber reinforced, aramid-fiber reinforced, or the like.

[0062] The first film 24 can also be referred to as a liquid barrier or liquid barrier. The first film 24 is low-temperature resistant, so it will not be damaged even if the cryogenic fluid 2 escapes from the inner tank 9, for example, in the event of a leak. The first film 24 can be constructed from a plurality of adjacent film webs that are bonded together, for example, glued or welded. This enables very simple and quick installation of the first film 24.

[0063] The tank 1 further comprises a second film 25, which lines the inside of the concrete outer tank 5. The second film 25 is in the Fig. 2shown with a dashed line. The second film 25 can line the outer tank base 7, the outer tank wall 6, and the outer tank roof 8 on the inside. The second film 25 is a liner or can be referred to as such. In contrast to the first film 24, the second film 25 is not only liquid-tight, but also gas-tight. The second film 25 can also be referred to as a diffusion barrier, gas barrier, or gas barrier. The second film 25 seals the concrete outer tank 5 in a gas-tight manner. Accordingly, the second film 25 has a liquid-tight and gas-impermeable or gas-tight design or construction.

[0064] The second film 25 is preferably made of the same material as the first film 24. The films 24, 25 can be integrally connected to one another at a connecting section 26, for example, welded or glued together. The first film 24 is arranged between the second compensating layer 21 and the load distribution plate 22 and extends upwards on the inside, i.e., facing the inner tank wall 10, along the casing 23 and covers it.

[0065] The second film 25 is arranged between the first compensating layer 20 and the outer tank base 7 and runs upwards along the outer tank wall 6, so that the second film 25 covers the outer side of the shell 23. This means that the second film 25 is arranged between the shell 23 and the outer tank wall 6. The second film 25 can be integrally connected, for example, glued, to both the outer tank wall 6 and the shell 23. Furthermore, the second film 25 can also be integrally connected to the outer tank base 7. The second film 25 can cover the entire outer tank wall 6. As the Fig. 2 shows, the first leveling layer 20, the insulation layers 17, 18, the jacket 23 and the second leveling layer 21 are completely accommodated between the foils 24, 25.

[0066] If the cryogenic fluid 2 escapes from the inner tank 9, for example, in the event of a leak, the first film 24 prevents the liquid phase of the cryogenic fluid 2 from penetrating the floor insulation 15 in the direction of the foundation 3. This reliably prevents both the penetration of the cryogenic fluid 2 into the floor insulation 15 and the penetration of the cryogenic fluid 2 to the outer tank floor 7. Without the first film 24, the foundation 3 could be undesirably exposed to impermissibly low temperatures, which could induce strong bending stresses in the foundation 3. This could lead to damage to the foundation 3. This applies in particular if the foundation 3 is supported on supports. The first film 24 reliably prevents the effects explained above. The second film 25 ensures the gas-tightness of the tank 1 and prevents moisture from penetrating the floor insulation 15 from the outside.

[0067] Because the films 24, 25 are very thin and therefore flexible, only minimal forces are exerted on the second film 25, even when it is bonded to the outer tank wall 6. Compared to a second bottom and a liner made of steel plates, the first film 24 can be installed much faster and with less labor. This significantly reduces installation costs. Material costs are also significantly reduced. Installation of the films 24, 25 is further simplified by the fact that they can be installed as individual film strips, which are bonded together after installation.

[0068] Pre-assembly of the foils 24, 25 is therefore not necessary. Although the present invention has been described using exemplary embodiments, it is capable of being modified in many ways, provided that it does not deviate from the scope of claim 1. Reference symbols used

[0069] 1Tank 2Fluid 3Foundation 4Soil 5Outer tank 6Outer tank wall 7Outer tank floor 8Outer tank roof 9Inner tank 10Inner tank wall 11Inner tank floor 12Cover 13Strut 14Insulating element 15Floor insulation 16Gap 17Insulating layer 18Insulating layer 19Foam glass block 20Leveling layer 21Leveling layer 22Load distribution plate 23Shell 24Foil 25Foil 26Connecting section MSymmetry axis

Claims

1. A tank (1) for storing a cryogenic fluid (2), in particular for storing liquefied natural gas, with an outer tank (5), an inner tank (9) which is arranged within the outer tank (5), a base insulation (15) which is arranged between an outer tank base (7) of the outer tank (5) and an inner tank base (11) of the inner tank (9), a liquid-tight first film (24) which is arranged between the outer tank base (7) and the inner tank base (11), and a gas-tight second film (25) arranged between the first film (24) and the outer tank base (7), wherein the outer tank base (7) and an outer tank wall (6) are made of concrete and the inner tank (9) is made of a metal material, wherein the films (24, 25) are elastically deformable, wherein the second film (25) is integrally bonded to the outer tank wall (6) of the outer tank (5), in particular glued thereto.

2. The tank according to claim 1, wherein the films (24, 25) comprise a metal, in particular aluminum.

3. The tank according to claim 1 or 2, wherein the films (24, 25) are fiber-reinforced, in particular glass fiber-reinforced.

4. The tank according to any of claims 1-3, wherein the second film (25) is arranged between the base insulation (15) and the outer tank base (7).

5. The tank according to any of claims 1-4, wherein the second film (25) completely covers the outer tank wall (6).

6. The tank according to any of claims 1-5, wherein the first film (24) is arranged at least in portions within the base insulation (15).

7. The tank according to any of claims 1-6, wherein the base insulation (15) has a pressure-resistant insulating layer (17, 18), in particular a foam glass block layer, a perlite concrete layer, a wood layer or a reinforced polyurethane layer, and wherein the first film (24) is arranged between the insulating layer (17, 18) and the inner tank base (11).

8. The tank according to claim 7, wherein the base insulation (15) has a plurality of insulating layers (17, 18) between which the first film (24) is arranged.

9. The tank according to claim 7 or 8, wherein the base insulation (15) comprises a load distribution plate (22), wherein the load distribution plate (22) is arranged between the inner tank base (11) and the insulating layer (17, 18), and wherein the first film (24) is arranged between the load distribution plate (22) and the insulating layer (17, 18).

10. The tank according to any of claims 7-9, wherein the base insulation (15) comprises an equalizing layer (20), and wherein the equalizing layer (20) is arranged between the outer tank base (7) and the insulating layer (17, 18).

11. The tank according to claim 10, wherein the second film (25) is arranged between the outer tank base (7) and the equalizing layer (20).

12. The tank according to any of claims 1-11, wherein the base insulation (15) has a cylindrical jacket (23) which is arranged between the outer tank (5) and the inner tank (9), and wherein the first film (24) is provided on the inside and the second film (25) is provided on the outside of the jacket (23).

13. The tank according to any of claims 1-12, wherein the first film (24) is integrally bonded to the second film (25).

14. The tank according to any of claims 1-13, wherein the outer tank (5) has an outer tank roof (8) that is made of concrete or steel.