Watertight tank
The sealed tank design with interlocking locking pieces and modular blocks addresses the issue of storing incompatible liquefied gases by ensuring robust attachment and maintaining tank integrity, simplifying manufacturing and enhancing safety.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- GAZTRANSPORT & TECHNIGAZ SA
- Filing Date
- 2024-12-20
- Publication Date
- 2026-06-26
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Title of the invention: Watertight tank technical field
[0001] The invention relates to the field of leak-proof tanks. In particular, the invention relates to the field of leak-proof tanks for the storage and / or transport of a liquefied gas. Technological background
[0002] In the prior art, sealed tanks for the storage of a liquefied gas are known. Such a sealed tank comprises, for example, a tank wall having a multilayer structure which includes successively, from the inside of the tank, a primary sealed membrane intended to be in contact with a liquefied gas contained in the tank, a primary insulating barrier, a secondary sealed membrane and a secondary insulating barrier intended to be fixed to a supporting structure. Summary of the invention
[0003] The inventors observed that, in the case of storing a liquefied gas other than liquefied natural gas (LNG) in tanks initially designed to store LNG, if the primary leak-proof membrane is damaged or has an imperfection that allows liquid gas to pass into the inter-membrane space, the tanks designed to store LNG would not always allow the tank to be kept in safe operation. This is because the components located below the primary membrane of tanks designed to store LNG are made of materials that deteriorate upon contact with certain liquefied gases.
[0004] For example, in the case of a tank suitable for use in storing LNG, the elements located under the primary membrane will not necessarily be suitable for contact with another liquefied gas, such as ammonia.
[0005] On the other hand, liquid ammonia, which is a denser liquid and therefore heavier than LNG for example, would have greater stresses transmitted to the primary sealing membrane and could therefore cause damage to a primary sealing membrane.
[0006] There is therefore a real need to design or improve tanks intended to receive liquefied gas, particularly for receiving liquefied gas that is incompatible with the underlying insulation elements, especially when the thermal insulation consists of polypropylene or polyurethane foam, or plywood. Indeed, contact between these elements and certain liquefied gases such as ammonia leads to a significant loss of their mechanical strength.
[0007] One idea underlying the invention is to solve at least some of the aforementioned problems.
[0008] Another idea underlying the invention is to produce a sealed tank suitable for receiving a liquefied gas, in particular a gas incompatible with certain thermally insulating materials, for example liquefied ammonia which is at approximately -33°C at atmospheric pressure.
[0009] Another idea underlying the invention is to create an improved sealed tank.
[0010] According to one embodiment, the invention provides a sealed tank for the storage of a liquefied gas, the sealed tank comprising a tank wall, the tank wall comprising, along a thickness direction of the tank wall: - a fixing wall having an internal end; - and a metallic waterproof membrane, wherein the waterproof membrane comprises at least one external face, at least a portion of which is fixed against the internal end of the fixing wall by an anchoring device, in which the fixing wall has a retaining housing, in which the anchoring member has a fixing wall-side locking piece located in the retaining housing and a membrane-side locking piece welded against at least a portion of the outer face of the sealing membrane and projecting from at least a portion of the outer face of the sealing membrane in the thickness direction of the tank wall, the fixing wall-side locking piece and the membrane-side locking piece being fixed by interlocking.
[0011] Thanks to these features, the sealing membrane is effectively fixed to the fixing wall. Furthermore, the locking piece protruding from the sealing membrane facilitates the manufacture of the tank wall and thus simplifies the tank manufacturing process.
[0012] According to embodiments, such a tank may include one or more of the following characteristics.
[0013] In one embodiment, the metallic waterproof membrane comprises metal sheets welded together at overlapping zones, an overlapping zone comprising an edge portion of a first metal sheet overlapped with an edge portion of a second metal sheet adjacent to the first metal sheet. In one embodiment, the locking piece on the membrane side is welded to the outer face of the waterproof membrane at a distance from the overlapping zone.
[0014] Thanks to these characteristics, the locking piece on the membrane side is not at risk of being damaged or deformed by the application of heat during the welding of the edge portions of the metal sheets.
[0015] The fixing wall can be made in many ways. The fixing wall can be made, for example, by spacer blocks, by modular blocks of an insulating barrier, such as insulating panels or insulating boxes, by a load-bearing wall, for example made of concrete or steel, or by any combination of these elements.
[0016] According to one embodiment, the metallic sealing membrane is an internal sealing membrane intended to be in contact with the liquefied gas contained in the tank, the fixing wall comprising an external metallic sealing membrane and a modular block, the external metallic sealing membrane being located opposite the internal sealing membrane, the modular block having an external end, a flat internal face parallel to the external end, the modular block having the retaining housing located between the internal face and the external end of the modular block, the external end of the modular block being positioned against the external sealing membrane, the internal sealing membrane is spaced from the external sealing membrane by the modular block and comprises at least one external face of which at least a portion is fixed against the internal face of the modular block by the anchoring member,the inner end of the fixing wall comprising the inner face of the modular block.
[0017] Thanks to these features, the attachment of the internal sealing membrane to the modular block is effective. Furthermore, the locking piece protruding from the internal sealing membrane facilitates the fabrication of the tank wall and thus simplifies the manufacturing of the tank.
[0018] In the presence of a modular block, the locking piece on the fixing wall side can also be called the locking piece on the modular block side because it will then be located in the retaining housing of the modular block.
[0019] According to one embodiment, each metal sheet of the waterproof membrane has corrugations spaced from each other by flat areas, at least a portion of the external face of the waterproof membrane being a portion of the external face of said first flat area.
[0020] According to one embodiment, each metal sheet of the waterproof membrane has parallel corrugations spaced apart from each other by flat areas, each flat area being delimited by two adjacent parallel corrugations of said metal sheet.
[0021] According to one embodiment, the corrugations of the waterproof membrane comprise a first corrugation and a second corrugation perpendicular to the first corrugation, a flat area being located between the first and second corrugations.
[0022] According to one embodiment, the locking is performed by a rectilinear translational movement of one of the locking piece on the fixing wall side and the locking piece on the membrane side relative to the other of the locking piece on the fixing wall side and the locking piece on the membrane side.
[0023] According to one embodiment, the rectilinear translation movement is carried out by the wall-side locking piece in a second direction perpendicular to the thickness direction of the tank wall, between an unlocked position in which the membrane-side locking piece can be inserted and removed from the retaining housing in the thickness direction of the tank wall, and a locked position in which the membrane-side locking piece is locked to the wall-side locking piece.
[0024] According to one embodiment, in the locking position, a portion of the stop of the locking piece on the fixing wall side is against a portion of the stop of the locking piece on the membrane side along the thickness direction of the tank wall.
[0025] Thanks to these characteristics, the stop portions increase friction, making the locking more robust by preventing slippage and thus improving the resistance to separation of the locking piece on the wall side from the locking piece on the membrane side. Therefore, such an assembly increases the tank's service life.
[0026] According to one embodiment, the membrane-side locking piece has a rod protruding from the internal sealing membrane, the rod having a fixing head forming the stop portion intended to be positioned, in the locking position, against the stop portion of the fixing wall-side locking piece, in order to allow the locking of the membrane-side fixing piece to the fixing wall-side locking piece.
[0027] According to one embodiment, the fastening head has a conical shape. The conical shape makes it easier to insert the fastening head into the through hole of the locking piece on the wall side.
[0028] According to one embodiment, the rod has a protrusion intended to position itself, in the locking position, against the stop portion of the locking piece on the fixing wall side.
[0029] According to one embodiment, the rod has a notch intended to be positioned, in the locking position, against the stop portion of the locking piece on the fixing wall side.
[0030] According to one embodiment, the locking piece on the wall side of the fixing has a through hole along the thickness direction of the tank wall, the through hole having a first zone and a second zone of smaller width that the first zone is spaced from the first zone in said second direction, and in which the membrane-side locking piece passes through the first zone in the unlocked position and the second zone in the locked position.
[0031] Thus, the first zone has dimensions allowing reversible or mobile insertion of the locking piece on the membrane side and the second zone has dimensions allowing the locking of the locking piece on the membrane side by preventing its release under normal conditions of use of the tank.
[0032] According to one embodiment, the locking piece on the fixing wall side comprises a locking bar extending in said second direction and passing through the retaining housing of the modular block in said second direction.
[0033] According to one embodiment, the membrane-side locking piece is a first membrane-side locking piece and the modular block is a first modular block, wherein a second modular block is disposed on the external waterproof membrane and fixed against the external waterproof membrane in a position adjacent to the first modular block, the second modular block having an external end, a flat inner face parallel to the external end, the external end being positioned against the external waterproof membrane, wherein the second modular block has a retaining housing located between the inner face and the external end of the second modular block, the portion of the external face of the internal waterproof membrane being a first portion,in which the internal sealing membrane is separated from the external sealing membrane by the second modular block and comprises at least a second portion of the external face of said second flat zone which is fixed against the internal face of the second modular block by the anchoring member, in which the locking bar passes through the retaining housing of the second modular block in said direction perpendicular to the thickness direction of the tank wall, the anchoring member comprising a second locking piece on the membrane side welded against said second flat zone and projecting from at least a second portion of the external face of the internal sealing membrane in the thickness direction of the tank wall, the second locking piece on the membrane side being fixed to the locking bar by interlocking.
[0034] Thanks to these features, the modular block-side locking mechanism allows, with a single translational movement, the locking or unlocking of at least two flat portions of the internal sealing membrane to at least two aligned modular blocks. Such a configuration facilitates and accelerates the assembly of a tank, while allowing for robust locking. Depending on the length of the locking bar, this arrangement can be repeated more than twice, for example between three and ten times, to lock or unlock multiple membrane-side locking pieces in a single operation.
[0035] According to one embodiment, the retaining housing of the first modular block has a through opening perpendicular to the wall thickness direction, allowing the locking bar to pass through. According to another embodiment, the retaining housing of the second modular block has a through opening perpendicular to the wall thickness direction, allowing the locking bar to pass from the retaining housing of the first modular block to the retaining housing of the second modular block.
[0036] According to one embodiment, the locking bar is an elongated flat piece. This facilitates the insertion of the locking bar into a retaining housing.
[0037] According to one embodiment, the locking bar is rigid, for example, the locking bar is metallic or made of thermoplastic. Thanks to these characteristics, the tank has a robust fastening that allows the flat portion of the internal sealing membrane to be securely pressed against the inner face of the modular block.
[0038] According to one embodiment, the external waterproof membrane comprises parallel corrugations spaced apart from each other by flat areas.
[0039] According to one embodiment, a first flat area of the external waterproof membrane and a second flat area of the external waterproof membrane being separated from each other by a corrugation, the first modular block and the second modular block having a height greater than the height of the corrugation, the locking piece passing over said corrugation.
[0040] Thus, the same locking piece can lock several modular blocks under the conditions of an external sealed membrane having undulations between the modular blocks.
[0041] According to one embodiment, the external end of the modular block is located on a flat area of the external waterproof membrane, for example only located on a flat area of the external waterproof membrane.
[0042] According to one embodiment, the external end of the modular block is located on several flat areas of the external waterproof membrane, for example on two adjacent flat areas separated from each other by a corrugation.
[0043] According to one embodiment, the internal housing of the first modular block and the internal housing of the second modular block are located above the height of the corrugation. Thus, the locking piece can be positioned so as to pass over the corrugations without touching said corrugations.
[0044] According to one embodiment, the internal housing of the first modular block and the internal housing of the second modular block are located opposite each other.
[0045] Thus, the insertion of the locking piece, and in particular the locking bar, into the internal housing of the first modular block and the internal housing of the second modular block is facilitated.
[0046] In one embodiment, one of the membrane-side locking piece and the fixing wall-side locking piece is elastically deformable and able to be locked by snapping to the other of the membrane-side locking piece and the fixing wall-side locking piece.
[0047] Thus, locking the membrane-side locking piece to the fixing wall-side locking piece is facilitated.
[0048] According to one embodiment, the snap-in is performed by a rectilinear translational movement of the locking piece on the membrane side, along the thickness direction of the wall.
[0049] According to one embodiment, one of the locking piece on the fixing wall side and the locking piece on the membrane side which is elastically deformable clamps the other of the locking piece on the fixing wall side and the locking piece on the membrane side.
[0050] Thus, during locking, the elastic locking piece designed to grip the other temporarily moves apart under the force exerted on the other locking piece during insertion. This deformation allows the elastic locking piece to adjust and open sufficiently to permit the passage or engagement of the other locking piece. Once in the locked position, the locking piece tends to return to its initial shape, gripping the other locking piece. This configuration ensures a stable and secure fastening of the two pieces relative to each other.
[0051] According to one embodiment, one of the locking piece on the fixing wall side and the locking piece on the membrane side which is elastically deformable is housed in the other of the locking piece on the fixing wall side and the locking piece on the membrane side.
[0052] Thus, during locking, one of the locking pieces—either the locking piece on the fixing wall side or the locking piece on the membrane side—which is elastic, deforms by compressing upon itself when inserted into the other piece. Once inserted, the elastic locking piece returns to its initial shape, thereby exerting outward pressure against the inner wall of the other piece, thus ensuring a secure lock between the two locking pieces.
[0053] According to one embodiment, the locking piece on the fixing wall side comprises a rod projecting from the fixing wall, optionally from the external sealing membrane, the locking piece on the membrane side being snapped onto the rod.
[0054] According to one embodiment, one of the locking piece on the fixing wall side and the locking piece on the membrane side has a return for snapping.
[0055] According to one embodiment, the locking piece on the fixing wall side and the locking piece on the membrane side have a return for snapping.
[0056] According to one embodiment, the return is a protrusion projecting outwards or inwards from the locking piece on the modular block side and / or from the locking piece on the membrane side.
[0057] According to one embodiment, the locking piece on the fixing wall side and / or the locking piece on the membrane side has rotational symmetry. For example, the locking piece on the fixing wall side and / or the locking piece on the membrane side has the shape of a right circular cylinder or a right circular cone.
[0058] In one embodiment, the outer waterproof membrane has parallel corrugations spaced apart. In another embodiment, the modular block has lateral ends connecting the outer end to the inner face; the lateral ends of the modular block have a first lateral end extending parallel to one of said corrugations of the outer waterproof membrane and facing said corrugation; the inner face has a first end portion partially overhanging said corrugation.
[0059] Thanks to these characteristics, the modular block can be positioned partially above a corrugation of the external waterproof membrane. As a result, the transmission of hydrostatic pressure forces to the underlying elements is optimal and the load-bearing capacity of the internal waterproof membrane is satisfactory.
[0060] According to one embodiment, the modular block is fixed against the external waterproof membrane via a screw-nut system.
[0061] In one embodiment, the modular block comprises a retaining surface cooperating with the screw-nut system to fix the modular block against the external waterproof membrane. In one embodiment, the retaining surface is located between the retaining housing and the outer end of the modular block, preferably at the center of the modular block.
[0062] According to one embodiment, the modular block comprises support ribs located under the inner face between the lateral ends and hollow cells located between the support ribs.
[0063] Thus, the modular block is reinforced by the support ribs. In addition, the hollow cells allow for the inerting of the internal space of the modular block, permitting the passage of gas molecules between the hollow cells located inside the modular block and the inter-membrane space located between the inner and outer airtight membranes.
[0064] According to one embodiment, the modular block is made of a material compatible with the liquefied gas which is intended to be contained in the tank.
[0065] According to one embodiment, the modular block is a spacer block comprising aluminum or a thermoplastic material.
[0066] In one embodiment, the spacer block comprises an aluminum alloy, for example, aluminum alloy 6082. In another embodiment, the spacer block comprises more than 50% aluminum by mass. In another embodiment, the spacer block consists of aluminum.
[0067] Thanks to these characteristics, the modular block is compatible with ammonia; that is, the modular block is not damaged by contact with liquid or gaseous ammonia, meaning that the physical properties of the modular block, which primarily support the internal membrane, are not altered by contact with ammonia. Consequently, thanks to these characteristics, if the internal sealed membrane is damaged and allows liquid or gaseous ammonia to pass into the inter-membrane space, the tank containing the damaged internal membrane can continue to operate without having to empty the tank.
[0068] The modular block is in particular considered compatible if it can be in contact with liquid or gaseous ammonia for at least 8 days without its carrying capacity being altered.
[0069] According to one embodiment, the spacer block comprises aluminum and is obtained by extrusion.
[0070] According to one embodiment, the thermoplastic material is chosen from: high-density polyethylene, polypropylene and high-impact polystyrene.
[0071] According to one embodiment, the thermoplastic spacer block comprises fibers, for example long fibers.
[0072] According to one embodiment, the composite spacer block is obtained by thermoforming or by injection.
[0073] According to one embodiment, the spacer block does not include thermally insulating materials.
[0074] According to one embodiment, the modular block comprises a thermally insulating material.
[0075] According to one embodiment, the modular block is a thermally insulating panel.
[0076] According to one embodiment, the thermally insulating panel comprises polyurethane foam sandwiched between two rigid plates, for example plywood.
[0077] In one embodiment, the modular block is a thermally insulating box comprising thermally insulating packing. In one embodiment, the thermally insulating packing is, for example, perlite or mineral wool. The thermally insulating box is, for example, made of plywood.
[0078] According to one embodiment, the load-bearing structure forms the fixing wall, the fixing wall optionally being a concrete wall, the load-bearing structure comprising the retaining housing, the internal waterproof membrane being fixed against the internal end of the load-bearing structure by the anchoring device.
[0079] According to one embodiment, a metal sheet of the internal waterproof membrane or of the external waterproof membrane has a general rectangular shape.
[0080] According to one embodiment, the parallel corrugations of each metal sheet of the internal or external waterproof membrane constitute a first series of corrugations, each metal sheet also has a second series of corrugations parallel to each other and perpendicular to the first series of corrugations, thus forming flat areas each located between two adjacent corrugations of the first series of corrugations and two adjacent corrugations of the second series of corrugations.
[0081] According to one embodiment, the first series of undulations is a series of small undulations. In this case, the second series of undulations can be a series of large undulations.
[0082] According to another embodiment, the first series of undulations is a series of large undulations. In this case, the second series of undulations can be a series of small undulations.
[0083] According to yet another embodiment, the first series of undulations and the second series of undulations have the same height. According to another embodiment, the first series of undulations and the second series of undulations have different heights.
[0084] According to one embodiment, the undulations protrude towards the inside of the tank.
[0085] According to one embodiment, a metal sheet covers a series of n blocks modular units of the aforementioned arrangement on x flat areas, n and / or x being between 2 and 20, preferably between 10 and 16. For example, a rectangular metal sheet can cover two longitudinal and parallel lines each comprising 5 to 8 spacer blocks arranged on 5 to 8 flat areas.
[0086] According to one embodiment, the tank comprises a modular block per flat area present on a metal sheet.
[0087] According to one embodiment, the adjacent modular blocks are spaced by an undulation of the external waterproof membrane.
[0088] According to one embodiment, the locking bar passes through the retaining slots of the series of n modular blocks aligned along the length of the metal sheet. For example, the locking bar passes through 5 to 8 modular blocks.
[0089] According to one embodiment, the locking bar passes through the retaining housings of the series of n modular blocks aligned in the width of the metal sheet.
[0090] According to one embodiment, the locking bar passes through the retaining housings of n aligned modular blocks, the locking bar being positioned under one or more metal sheets, for example positioned under one or two metal sheets.
[0091] According to one embodiment, the retaining housings are located at a height greater than the height of the corrugations separating the retaining housings, the locking bar passing over said corrugations.
[0092] According to one embodiment, the fixing wall comprises an auxiliary barrier on which the external sealing membrane is positioned, and the auxiliary barrier comprises, from the outside to the inside of the tank: a secondary thermally insulating layer intended to be fixed to a load-bearing structure, an auxiliary sealing membrane resting against the secondary thermally insulating layer and an intermediate thermally insulating layer located against the secondary sealing membrane, the external sealing membrane being positioned against the intermediate thermally insulating layer.
[0093] For example, the secondary and / or intermediate thermally insulating layer may include insulating elements made of various materials, including materials incompatible with ammonia such as polyurethane foam or glass wool.
[0094] According to one embodiment, the auxiliary barrier comprises a modular block fixed to the supporting structure, the modular block comprising successively, along a thickness direction of the modular block, a secondary thermally insulating layer, a waterproof membrane made of composite material which rests against the secondary thermally insulating layer, an intermediate thermally insulating layer covering the waterproof membrane made of composite material.
[0095] According to one embodiment, the auxiliary waterproof membrane is a flexible membrane made of composite material bonded to the secondary thermally insulating layer.
[0096] According to one embodiment, the waterproof membrane made of composite material comprises a metallic sheet sandwiched between two layers of unresined glass fibers, also known as Triplex®.
[0097] According to one embodiment, the aforementioned tank wall is a bottom wall of the tank when the tank is in a position of use.
[0098] According to one embodiment, the aforementioned tank wall is a side wall of the tank when the tank is in a position of use.
[0099] According to one embodiment, the tank comprises a plurality of the aforementioned walls.
[0100] According to one embodiment, the internal waterproof membrane is intended to be in contact with ammonia, butane, propane or ethane, preferably with ammonia.
[0101] According to one embodiment, the tank contains liquefied gas.
[0102] According to one embodiment, the invention also provides a method for adapting a a sealed tank initially intended for the storage of a first liquefied gas, the process comprising: - fix a modular block of the aforementioned type on the inside of the tank on at least one flat area of a sealed membrane, in which the sealed membrane is a primary membrane belonging to a sealed tank wall for the storage of the first liquefied gas such as LNG, the sealed membrane being metallic and comprising a first series of parallel corrugations, - and fix at least one flat area of an internal metallic waterproof membrane against the inner face of the modular block via the aforementioned anchoring device.
[0103] The use of this process makes it possible in particular to anchor the modular block directly onto a primary membrane belonging to a sealed and thermally insulating tank wall for the storage of LNG in order to make the tank compatible with ammonia.
[0104] Such tanks may be part of an onshore storage facility, for example for storing ammonia, or be installed in a floating structure, whether coastal or deep-water, including a ship, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO), and others. Such tanks may also serve as fuel tanks in any type of ship.
[0105] According to one embodiment, the supporting structure rests on the ground, on a seabed or is part of a ship.
[0106] According to one embodiment, an onshore installation comprises a supporting structure and the aforementioned tank disposed in the supporting structure.
[0107] According to one embodiment, a ship for the transport of a liquefied gas comprises a double hull and the aforementioned tank disposed in the double hull.
[0108] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned vessel, insulated pipes arranged to connect the tank installed in the hull of the vessel to a floating or land-based storage facility and a pump to drive a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the vessel's tank.
[0109] According to one embodiment, the invention also provides a method for loading or unloading such a vessel, in which a liquefied gas is conveyed through insulated pipelines from or to a floating or land-based storage facility to or from the vessel's tank. Brief description of the figures
[0110] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.
[0111] Fig. 1 represents a partial schematic cross-sectional view of a wall of a sealed tank.
[0112] [Fig.2] is a partial, enlarged top view of zone I of [Fig.1], representing a tank wall according to a first embodiment, in which the internal sealing membrane has been intentionally omitted.
[0113] Fig. 3 is an enlarged view, according to a first cross-section, of zone I of Fig. 1, representing a tank wall according to the first embodiment.
[0114] Fig. 4 is an enlarged view, according to a second cutting plane, of zone I of Fig. 1, representing a tank wall according to the first embodiment.
[0115] [Fig.5] is an enlarged, top, partial view of the locking bar according to the first embodiment.
[0116] [Fig.6] is an enlarged, partial, perspective view of zone I of [Fig.1], according to the first embodiment, in an unlocked position.
[0117] [Fig.7] is an enlarged, partial, perspective view of zone I of [Fig.1], according to the first embodiment, in a locked position.
[0118] Fig. 8 is an enlarged, cross-sectional view of zone I of Fig. 1, representing a tank wall according to a second embodiment.
[0119] Fig. 9 is an enlarged, cross-sectional view of zone I of Fig. 1, representing a tank wall according to a third embodiment.
[0120] [Fig.10] is an enlarged, partial, cross-sectional view of zone I of [Fig.1], representing a tank wall according to a fourth embodiment.
[0121] The [Fig. 11] is a schematic cutaway representation of a ship's tank and a loading / unloading terminal for this tank.
[0122] The [Fig. 12] is a partial cross-sectional view of a tank wall according to a fifth embodiment.
[0123] The [Fig. 13] is a partial, exploded perspective view of a tank wall according to a sixth embodiment.
[0124] Fig. 14 is a partial cross-sectional view of the tank wall according to the sixth embodiment. Description of the implementation methods
[0125] By convention, the terms "external" and "internal" are used to define the relative position of one element with respect to another, by reference to the inside and outside of the tank.
[0126] With reference to [Fig. 1], a watertight tank wall is described in general terms according to various embodiments below. Such a wall structure can be used to construct substantially all the walls of a tank, for example, a polyhedral tank. In this respect, the terms 'on', 'overhanging', 'above', 'superior', and 'high' generally refer to a position located towards the interior of the tank and therefore do not necessarily coincide with the notion of 'high' in the Earth's gravitational field. Similarly, the terms 'under', 'below', 'lower', and 'low' generally refer to a position located towards the exterior of the tank and therefore do not necessarily coincide with the notion of 'low' in the Earth's gravitational field.
[0127] The tank wall 1 has a multilayer structure comprising, along the thickness direction E of the tank wall 1, from the outside to the inside of the tank: a load-bearing structure 3, an auxiliary barrier 2, an external sealing membrane 4 and a plurality of modular blocks 5 forming a fixing wall 8 and an internal sealing membrane 6 fixed to the fixing wall and intended to be in contact with the liquefied gas such as liquid ammonia.
[0128] The load-bearing structure 3 may in particular be formed of self-supporting metal sheets or, more generally, of any type of rigid partition having appropriate mechanical properties, such as a concrete partition or wall or a partition formed by the double hull of a ship.
[0129] The auxiliary barrier 2 is thermally insulating and is fixed to the load-bearing structure 3 and comprises, for example, a plurality of thermally insulating panels (not shown) anchored to the load-bearing structure 3.
[0130] The auxiliary barrier 2 may further comprise a secondary flexible membrane made of composite material (not shown) bonded against the thermally insulating panels.
[0131] The auxiliary barrier 2 may further comprise a second layer of thermally insulating panels bonded against the secondary flexible membrane.
[0132] The external sealing membrane 4 is metallic, preferably stainless steel. The external sealing membrane 4 has parallel corrugations 14 and flat areas 15 defined between the corrugations 14. The corrugations 14 project from the flat areas 15 towards the interior of the tank.
[0133] Similar to the external sealing membrane 4, the internal sealing membrane 6 is metallic, preferably made of stainless steel. The internal sealing membrane 6 has parallel corrugations 16 and flat areas 17 defined between the corrugations 16. The corrugations 16 project from the flat areas 17 towards the interior of the tank.
[0134] The undulations 16 and the undulations 14 as well as the flat areas 17 and the flat areas 15 are respectively located opposite each other.
[0135] The term "plane area" of the internal or external sealing membrane must be understood in the context of the invention as being flat on the side of the internal face and on the side of the external face.
[0136] Tank walls according to several embodiments will be described in more detail below.
[0137] In Figures 2 to 7, the elements identical or similar to those in [Fig. 1] bear the same reference numerals incremented by 100.
[0138] In relation to figures 2 to 7, a first variant of a sealed tank wall 101 for the storage of liquefied gas such as ammonia is described below.
[0139] The tank wall 101 comprises an external watertight membrane 104 having a series of small parallel corrugations 118 and further comprising a series of large corrugations 114 perpendicular to the small corrugations 118. The large corrugations 114 and the small corrugations 118 project towards the interior of the tank. The large corrugations 114 have a height greater than the height of the small corrugations 118.
[0140] Flat areas 115 of the external waterproof membrane 104 are defined between the small corrugations 118 and between the large corrugations 114.
[0141] Similar to the external sealing membrane, the internal sealing membrane 106 comprises a series of small parallel corrugations 119 and further comprises a series of large corrugations 116 perpendicular to the small corrugations 119. The large corrugations 116 and the small corrugations 119 project towards the interior of the tank. The large corrugations 116 have a height greater than the height of the small corrugations 119.
[0142] Figure 2 illustrates two adjacent spacer blocks 105 positioned on two adjacent flat areas 115. The two spacer blocks have the same characteristics, so the same reference numbers were used.
[0143] Each of the spacer blocks 105 is located on a flat area 115 of the external sealing membrane 104, as can be seen for example in figures 2 to 4.
[0144] The thickness of the spacer block 105 is here between the height of the small undulations 118 and the height of the large undulations 114.
[0145] The spacer block 105 has an external end 130 positioned against the flat area 115, a flat internal face 131 parallel to the external end 130 positioned against the flat area 117 of the internal sealing membrane 106 and four lateral ends connecting the external end 130 to the internal face 131.
[0146] The contour of the outer end 130 corresponds substantially to the contour of the flat area 115 and does not touch the toes of the small corrugations 118 and the large corrugations 114. A toe of a corrugation can be defined as the area in which the sealing membrane deflects towards the internal space of the tank. This deflection area is located between the corrugation and the flat area of the sealing membrane.
[0147] The four lateral ends develop between the outer end 130 and the inner face 131 of the spacer block 105 and comprise: two first lateral ends 132 facing each other and extending parallel to the small undulations 118, i.e. in the longitudinal direction of the small undulations 118, and two second lateral ends 133 facing each other and extending parallel to the large undulations 114, i.e. in the longitudinal direction of the large undulations 114. The lateral ends do not touch said undulations.
[0148] In the illustrated embodiment, the first two lateral ends 132 are turned respectively towards two small corrugations 118 without touching the two small corrugations 118. The first two lateral ends 132 extend outwards from the spacer block 105 such that the inner face 131 has a larger dimension than the outer end 130 in a direction transverse to the small corrugations 118, i.e. in a direction parallel to the large corrugations 114, so that two opposite end portions of the inner face 131 each partially overhang the adjacent small corrugation 118 and support a foot of a corrugation 119 of the internal sealing membrane 106. The first two lateral ends 132 have a concave shape which remotely follows the shape of a portion of the small corrugation 118.Similar to the first two lateral ends 132, the second two lateral ends 133 are turned respectively towards two large undulations 114 without touching the two large undulations 114. The two second lateral ends 133 develop. towards the outside of the spacer block 105 so that the inner face 131 has a larger dimension than the outer end 130 in a direction transverse to the large corrugations 114, i.e. in a direction parallel to the small corrugations 118, so that two portions of opposite ends of the inner face 131 each partially overhang the adjacent large corrugation 114 and support a foot of a corrugation 116 of the inner sealing membrane 106. The two second lateral ends 133 have a concave shape which remotely follows the shape of a portion of the large corrugation 114.
[0149] According to an alternative embodiment (not illustrated) of figures 2 to 7, the lateral ends do not overhang the large undulations 114 or the small undulations 118. In this case, the spacer block has a general shape of a rectangular parallelepiped.
[0150] The spacer block 105 further comprises a plurality of support ribs 134 which form hollow cells 135, a retaining housing 136 and a retaining surface 137.
[0151] The hollow cells 135 have the shape of a plurality of compartments. The plurality of supporting ribs 134 enables the spacer block 105 to support the internal waterproof membrane 106 and to resist the hydrostatic pressure forces exerted against the spacer block 105.
[0152] The retaining surface 137 is located between the retaining housing 136 and the flat area 115. The spacer block 105 is fixed against said flat area 115 via the retaining surface 137 and a screw-nut system, visible for example in [Fig. 8] and which is described below, with [Fig. 8]. Other fastening systems may also be used.
[0153] The retaining housing 136 is located above the retaining surface 137 and is delimited by a portion of two parallel grooves 134 spaced apart, a portion of the flat inner face 131 and a groove 134 located opposite the flat inner face 131.
[0154] The retaining housing 136 further includes a retaining groove 138 in which is housed a locking piece on the spacer side 109 having a locking bar 191.
[0155] The locking bar 191 is an elongated part extending along a direction X perpendicular to the thickness direction E of the tank wall. As illustrated in [Fig. 2], the same locking bar 191 passes through several retaining recesses 136 of several aligned spacer blocks 105 by passing over the small corrugations 118.
[0156] Indeed, the height of the retaining housing 136 and the height of the groove 138 are located above the small undulations 118, allowing the passage of the bar locking 191 over the small undulations 118, without touching the small undulations 118.
[0157] A flat area 117 of the internal sealing membrane 106 rests against the flat inner face 131 and is fixed to the spacer block 105 by locking a membrane-side locking piece 110 to the spacer-side locking piece 109. In this embodiment, there are as many membrane-side locking pieces 110 as there are spacer blocks 105. For example, [Fig. 2] illustrates two spacer blocks 105, and each of them has a membrane-side locking piece 110 located opposite one of the two spacer blocks 105.
[0158] The membrane-side locking piece 110 has a cylindrical rod 111 projecting from the flat area 117 of the internal sealing membrane 106. The cylindrical rod 111 has a circumference narrowing area 112 and a conical fixing head 113 located at one end of the rod.
[0159] In order to allow the fixing of the internal sealing membrane 106 to the spacer blocks 105, the internal face 131 of the spacer block 105 has a through hole 140 opening into the retaining housing 136 and the locking bar 191 has a through hole with two zones, a first zone 192 and a second zone 193 of smaller width, in particular visible in figures 5 to 7. The through hole 140 and the through hole with two zones being located opposite each other.
[0160] The internal sealing membrane 106 is attached to the spacer blocks 105 by attaching the membrane-side locking piece 110 to the spacer-side locking piece 109. To do this, the rod 111 is inserted both into the through-hole 140 and into the first zone 192 of the through-hole of the locking bar. The fastening head 113 is located below the locking bar 191. At this stage, the membrane-side locking piece 110 is not yet locked to the spacer-side locking piece 109, as can be seen in particular in [Fig. 6].
[0161] In order to lock the membrane-side locking piece 110 to the spacer-side locking piece 109, a rectilinear translational movement of the locking bar 191 is carried out relative to the membrane-side locking piece 110, along the direction X perpendicular to the thickness direction E of the wall and in the direction of the second zone 193. This movement places the fixing head 113 under the second zone 193 of the through orifice and moves the circumferential narrowing zone 112 which receives the thickness of the locking bar 191, to the level of the second zone 193, as particularly visible in [Fig.7].
[0162] The fastening head 113 has a diameter greater than the width of the second zone 193. Thus, in a locked position, the membrane-side locking piece 110 is locked to the spacer-side locking piece 109, plus Specifically, the junction between the circumference narrowing zone 112 and the fixing head forms a stop portion which is in contact with a stop portion of the locking bar 191. Therefore, the internal sealing membrane 106 is pressed and locked against the spacer block 105.
[0163] In the present embodiment, the head is conical in shape to facilitate insertion into the first zone 192 of the orifice.
[0164] Fig. 8 illustrates a second embodiment of the tank wall.
[0165] In [Fig.8], the elements identical or similar to those in Figures 2 to 7 bear the same reference numerals incremented by 100.
[0166] As previously stated, the spacer block 205 is fixed against the flat area 215 via the retaining surface 237 and a screw-nut system in which the spacer block 205 is fixed against the external sealing membrane 204. To do this, a threaded rod 220 is fixed to the flat area 215 of the external sealing membrane 204 such that the threaded rod 220 protrudes upwards, i.e., protrudes towards the inside of the tank. The spacer block 205 is then positioned on the flat area 215. The spacer block 205 is then fixed via a retaining surface 237 cooperating with a nut 222 and optionally a washer 223 interposed between the nut and the retaining surface.
[0167] The tank wall 201 differs from the tank wall 101 illustrated with figures 2 to 7 in that it does not have a locking bar and in that the locking piece 210 on the membrane side has an elastically deformable attachment 281 projecting from the internal sealing membrane 206 around a rod 228 also projecting from the internal sealing membrane 206.
[0168] The locking piece on the spacer side 209 of the tank wall 201 has a rotational symmetry and includes a hook piece 291 projecting into the interior of the tank from a bottom wall 239 of the retaining housing 236.
[0169] The elastically deformable fastener 281 and the hook piece 291 each have a return 221, 294. The return 221 and the return 294 are configured to match each other to allow snap-fit fastening.
[0170] In order to lock the membrane-side locking piece 210 to the spacer-side locking piece 209, a rectilinear translational movement of the elastically deformable fastener 281 is performed relative to the hook piece 291, along the thickness direction E of the wall. This rectilinear movement deforms the elastically deformable fastener 281 by compressing it towards the stem in order to house the return 221 in the hook piece 291 at the return 294. Once housed in the hook piece 291, the elastically deformable fastener 281 returns to its initial shape, thus exerting pressure towards its lateral ends against the inner wall of the hook piece 291, thereby ensuring a lock between the two locking parts to press the internal sealing membrane 206 against the spacer 205.
[0171] Fig. 9 illustrates a third embodiment of the tank wall.
[0172] In [Fig.9], elements identical or similar to those in [Fig.8] bear the same reference numbers incremented by 100.
[0173] The tank wall 301 differs from the tank wall 201 illustrated with [Fig.8] in that the threaded rod 320 used for fixing the spacer block to the external sealing membrane extends into the retaining housing 336 by passing through the retaining surface 337 and the bottom wall 339 of the retaining housing.
[0174] The locking piece on the spacer side 309 has a protrusion 391 having a rotational symmetry formed on the portion of the threaded rod located in the retaining housing 336.
[0175] The locking piece 310 on the membrane side has an elastically deformable fastener 381 projecting from the internal sealing membrane 306. The return 321 of the elastically deformable fastener 391 projects inwards from the elastically deformable fastener 381, in the direction of the protrusion 391.
[0176] In order to lock the membrane-side locking piece 310 to the spacer-side locking piece 309, a rectilinear translational movement of the elastically deformable fastener 381 is performed, along the thickness direction E of the tank wall 301, to insert the elastically deformable fastener 381 around the threaded rod 320 up to the protrusion 391. This rectilinear movement deforms the elastically deformable fastener 381 by moving it away in the opposite direction to the threaded rod 320 in order to open it sufficiently to allow the return 321 to pass under the protrusion 391. Then, the elastically deformable fastener 381 returns to its initial shape under the protrusion 391, allowing the elastically deformable fastener 381 to be fixed to the threaded rod by snapping the return 321 onto the protrusion. 391.Due to the effect of elasticity, the elastically deformable fastener 381 exerts pressure towards the threaded rod 320, allowing the return 321 to be pressed against the wall of the protrusion 391, thus ensuring a lock between the two locking pieces, allowing the internal sealing membrane 306 to be pressed against the spacer 305.
[0177] The return assembly 321 - protuberance 391 in the locking position prevents the locking piece on the membrane side 310 from being released to the locking piece on the spacer side 309 along the thickness direction E of the tank wall.
[0178] Fig. 10 illustrates a fourth embodiment of the tank wall.
[0179] In [Fig.10], the elements identical or similar to those in [Fig.8] bear the same reference figures incremented by 200.
[0180] The tank wall 401 differs from the tank wall 201 illustrated with [Fig.8] in that the locking piece on the spacer side 409 includes the elastically deformable attachment 491.
[0181] The elastically deformable attachment 491 projects into the interior of the tank from a bottom wall 439 of the retaining housing 436 and includes a return 494.
[0182] The locking piece on the spacer side 410 comprises, similarly to the first embodiment illustrated with figures 2 to 7, a cylindrical rod 411 projecting from the flat area 417 of the internal sealing membrane 406. The cylindrical rod 411 comprises a circumference narrowing area 412 and a fixing head 413 located at one end of the rod 411, the fixing head 413 having a conical shape.
[0183] In order to lock the membrane-side locking piece 410 to the spacer-side locking piece 409, a rectilinear translational movement of the rod 411 is performed, along the thickness direction E of the tank wall 401, to insert the fastening head 413 into the elastically deformable fastener 491. This rectilinear movement deforms the elastically deformable fastener 491, and in particular the return 494, by moving it away in the opposite direction to the direction of the rod 411 in order to open it sufficiently to allow the passage of the fastening head 413 and to allow the return 491 to be positioned in the circumferential narrowing zone 412 by snapping it into place. Indeed, the return 494 of the elastically deformable fastener 491 is configured to be housed and locked in the circumferential narrowing zone 412, as illustrated in [Fig. 10].
[0184] Fig. 12 illustrates an alternative embodiment of a wall of the tank 501, in which the fixing wall is a concrete wall 508 forming the load-bearing structure of the tank.
[0185] In [Fig.12], elements identical or similar to those in [Fig.3] bear the same reference numbers incremented by 400.
[0186] The concrete wall 508 has a plurality of retaining housings 536 opening at the level of the internal surface of the concrete wall 508.
[0187] The retaining housings 536 are located at a distance from an overlap zone 560 formed by welding between a portion of the edge of a first metal sheet and a portion of the edge of a second metal sheet. The portion of the edge of the second metal sheet includes a raised edge 561 overlapping the portion of the edge of the first metal sheet and welded to the portion of the edge of the first metal sheet.
[0188] Each retainer housing 536 comprising a locking piece 509 configured to cooperate with an inverted "L" shaped locking piece 510 projecting from a flat area 515 of the internal sealing membrane 506.
[0189] In order to lock the internal waterproof membrane 506 to the concrete wall 508, the locking pieces 510 are inserted through the opening of the retaining piece 536 and then slid towards the locking piece 509 on the concrete wall 508 side, i.e. in the direction X perpendicular to the thickness direction E of the wall.
[0190] Figures 13 and 14 illustrate an alternative embodiment of a tank wall 601 in which the fixing wall is a concrete wall 608 forming the load-bearing structure of the tank.
[0191] In Figures 13 and 14, the elements identical or similar to those in [Fig.3] bear the same reference numbers incremented by 500.
[0192] This variant also differs from the embodiment of [Fig.3] in particular in that the concrete wall 605 has a groove 655 opening at the level of the internal surface of the concrete wall 605.
[0193] The groove 655 includes a retaining element 656 conforming to the shape of the groove 655. The retaining element 656 has an internal space and has two protrusions 684 located opposite each other in the direction of the internal space in order to form a rail receiving an elongated part 657 having the retaining housing 636 into which a locking bar 691 is inserted.
[0194] The elongated part 657 has an opening 658 leading into the retaining housing 636 to allow the insertion and fixing of the locking part 610 membrane side to the locking bar 691.
[0195] The inner face of the concrete wall 605, the inner face of the retaining element 656 and the inner face of the elongated piece 657 form a flat surface to receive the internal waterproof membrane 606.
[0196] With reference to [Fig. 11], a cutaway view of a vessel 70 shows a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the vessel. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the liquefied gas contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the vessel, and two thermally insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72. The tank wall may be one of the aforementioned tank walls, for example, tank wall 1, 101, 201, 301, 501, 601.
[0197] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a marine or port terminal to transfer a cargo of liquefied gas from or to the tank 71.
[0198] Fig. 11 represents an example of a marine terminal comprising a loading and unloading berth 75, a subsea pipeline 76 and an onshore facility 77. The loading and unloading berth 75 is a fixed offshore facility comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 adapts to all ship sizes. An unshown connecting pipeline extends inside tower 78. The loading and unloading station 75 allows the ship 70 to be loaded and unloaded from or to the onshore facility 77. This facility includes liquefied gas storage tanks 80 and connecting pipelines 81 linked by the subsea pipeline 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore installation 77 over a long distance, for example 5 km, which allows the ship 70 to be kept a long distance from the coast during loading and unloading operations.
[0199] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 are used.
[0200] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.
[0201] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.
[0202] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.
Claims
Demands
1. Leak-proof tank (71) for the storage of a liquefied gas, the leak-proof tank comprising a tank wall (1, 101, 201, 301, 401, 501, 601), the tank wall comprising along a thickness direction (E) of the tank wall: - a fixing wall having an internal end; - and a metallic waterproof membrane (6, 106, 206, 306, 406, 506, 606) comprising metal sheets welded together at overlapping areas, an overlapping area comprising an edge portion of a first metal sheet covered with an edge portion of a second metal sheet adjacent to the first metal sheet, in which the waterproof membrane comprises at least one external face, at least a portion of which is fixed against the internal end of the fixing wall by an anchoring device, in which the fixing wall comprises a retaining housing (136, 236, 336, 436, 536, 636),in which the anchoring element comprises a wall-side locking piece (109, 209, 309, 409, 509) located in the retaining housing and a membrane-side locking piece (110, 210, 310, 410, 510, 610) welded against at least one portion of the outer face of the sealing membrane and projecting from at least one portion of the outer face of the sealing membrane in the thickness direction (E) of the tank wall at a distance from the overlap zone, the wall-side locking piece and the membrane-side locking piece being fixed by interlocking.
2. Tank according to claim 1, wherein each metal sheet of the sealing membrane has corrugations (16, 116, 216) spaced from each other by flat areas (17, 117, 217, 317, 417), wherein at least a portion of the outer face of the sealing membrane is a portion of the outer face of said first flat area.
3. A tank according to claim 1 or 2, wherein the metallic sealing membrane is an internal sealing membrane intended to be in contact with the liquefied gas contained in the tank, the fixing wall comprising an external metallic sealing membrane and a modular block, the external metallic sealing membrane being located opposite the internal sealing membrane, the modular block having an external end (130, 230, 330), an internal face (131, 231, 331, 431) flat parallel to the external end, the modular block having the retaining housing (136, 236, 336, 436, 536, 636) located between the internal face and the external end of the modular block, the external end of the modular block being positioned against the external sealing membrane, the internal sealing membrane is spaced from the external sealing membrane by the modular block and includes at least one external face of which at least a portion is fixed against the internal face of the modular block by the anchoring member, the internal end of the fixing wall including the internal face of the modular block.
4. Tank according to any one of claims 1 to 3, wherein the locking is effected by a rectilinear translational movement of one between the locking piece on the fixing wall side and the locking piece on the membrane side relative to the other between the locking piece on the fixing wall side and the locking piece on the membrane side.
5. Tank according to claim 4, wherein the rectilinear translation movement is carried out by the wall-side locking piece in a second direction (X) perpendicular to the thickness direction of the tank wall, between an unlocked position in which the membrane-side locking piece can be inserted and removed from the retaining housing in the thickness direction of the tank wall, and a locked position in which the membrane-side locking piece is locked to the wall-side locking piece.
6. Tank according to claim 5, wherein, in the locked position, a portion of the stop of the locking piece on the fixing wall side is abutted against a portion of the stop of the locking piece on the membrane side along the thickness direction of the tank wall.
7. Tank according to claim 5 or 6, wherein the locking piece on the wall side of the fixing has a through-hole along the thickness direction of the tank wall, the through-hole having a first zone (192) and a second zone (193) of smaller width than the first zone and spaced from the first zone in said second direction, and in which the membrane-side locking piece passes through the first zone in the unlocked position and the second zone in the locked position.
8. Tank according to any one of claims 5 to 7, wherein the wall-side locking piece has a locking bar (191) extending in said second direction and passing through the modular block retaining housing in said second direction.
9. Tank according to claim 8 taken in combination with claim 3, wherein the membrane-side locking piece is a first membrane-side locking piece and the modular block is a first modular block, and wherein a second modular block is disposed on the external sealing membrane and fixed against the external sealing membrane at a position adjacent to the first modular block, the second modular block having an external end, a flat inner face parallel to the external end, the external end being positioned against the external sealing membrane, wherein the second modular block has a retaining housing located between the inner face and the external end of the second modular block, wherein the portion of the external face of the internal sealing membrane is a first portion,in which the internal sealing membrane is separated from the external sealing membrane by the second modular block and comprises at least a second portion of the external face of said second flat zone which is fixed against the internal face of the second modular block by the anchoring member, in which the locking bar passes through the retaining housing of the second modular block in said direction perpendicular to the thickness direction of the tank wall, the anchoring member comprising a second locking piece on the membrane side welded against said second flat zone and projecting from at least a second portion of the external face of the internal sealing membrane in the thickness direction of the tank wall, the second locking piece on the membrane side being fixed to the locking bar by interlocking.
10. Tank according to claim 9, wherein the external sealing membrane has parallel corrugations (118, 218) spaced apart from each other by flat areas, a first flat area of the external sealing membrane and a second flat area of the external sealing membrane being separated from each other by a corrugation, the first modular block and the second modular block having a height greater than the height of the corrugation, the locking piece passing over said corrugation.
11. Tank according to any one of claims 1 to 4, wherein one of the membrane-side locking piece and the wall-side locking piece is elastically deformable and able to be locked by snapping to the other of the membrane-side locking piece and the wall-side locking piece.
12. Tank according to claim 11, wherein the snap-in is effected by a rectilinear translational movement of the membrane-side locking piece, along the wall thickness direction.
13. Tank according to any one of claims 11 to 12, wherein said one of the fixing wall-side locking piece and the membrane-side locking piece which is elastically deformable clamps the other of the fixing wall-side locking piece and the membrane-side locking piece.
14. Tank according to any one of claims 11 to 13, wherein the wall-side locking piece has a rod (320) projecting from the wall-side fixing, the membrane-side locking piece being snapped onto the rod.
15. Tank according to any one of claims 3 to 13, wherein the outer sealing membrane has parallel corrugations spaced apart and wherein the modular block has lateral ends (132, 133, 232) connecting the outer end to the inner face, the lateral ends (132, 232) of the modular block having a first lateral end extending parallel to one of said corrugations of the outer sealing membrane and turned towards said corrugation, the inner face having a first end portion partially overhanging said corrugation.
16. Tank according to any one of claims 2 to 14, wherein the fixing wall further comprises an auxiliary barrier (2) on which the external sealing membrane is positioned, wherein the auxiliary barrier comprises, from the outside to the inside of the tank: a secondary thermally insulating layer intended to be fixed to a load-bearing structure, an auxiliary sealing membrane resting against the secondary thermally insulating layer and an intermediate thermally insulating layer situated against the secondary sealing membrane, the external sealing membrane being positioned against the intermediate thermally insulating layer.
17. Vessel (70) for the transport of a liquefied gas, the vessel comprising a double hull (72) and a tank (71) according to any one of claims 1 to 16 disposed in the double hull.
18. Transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 17, insulated pipelines (73, 79, 76, 81) arranged to connect the vessel's tank (71) to a floating or land-based storage facility (77) and a pump to drive a flow of liquefied gas through the insulated pipelines from or to the floating or land-based storage facility to or from the vessel's tank.
19. A method of loading or unloading a ship (70) according to claim 17, wherein a liquefied gas is conveyed through insulated pipelines (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the ship (70).