Watertight tank

Abstract

The invention relates to a sealed tank comprising a tank wall (1) including: an external sealed membrane (4) having a first series of parallel corrugations (14) and flat areas (15); a spacer block (5) disposed on a flat area and fixed to the external sealed membrane, the spacer block having an external end, a flat inner face and lateral ends connecting the external end to the inner face, the external end being positioned against said flat area, the lateral ends having a first lateral end extending parallel to the first series of corrugations and turned towards a first corrugation of the first series of corrugations, the inner face having an end portion partially overhanging the first corrugation; an internal sealed membrane (6) spaced from the external sealed membrane by the spacer block and including a flat portion which is fixed against the inner face of the spacer block.Figure for the abridged version: 1.

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 successively includes a primary sealed membrane intended to be in contact with a product contained in the tank, a primary insulating barrier, a secondary sealed membrane and a secondary insulating barrier. Summary of the invention

[0003] The inventors observed that, in the case of liquefied gas storage, if the primary sealed membrane is damaged or has an imperfection that allows liquid gas to pass into the inter-membrane space, known tanks would not always allow the tank to be maintained in safe operation. This is because the components located below the primary membrane of known tanks are made of materials that deteriorate upon contact with certain liquefied gases.

[0004] Furthermore, in the case of an existing tank, for example in the case of a tank suitable for use in storing liquefied natural gas (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 carry out a process for adapting a sealed and thermally insulated tank initially intended for the storage of LNG in order to store another liquefied gas such as ammonia.

[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 intended to be installed in a supporting structure, the tank wall comprising, along a thickness direction of the tank wall: - an external metallic waterproof membrane comprising a first series of parallel corrugations and flat areas; - a spacer block positioned on at least one of the said flat areas of the external waterproof membrane and fixed to the external waterproof membrane, the spacer block having an external end, a flat internal face parallel to the external end and lateral ends connecting the external end to the internal face, the external end being positioned against said at least one flat area, the lateral ends having a first lateral end extending parallel to the first series of undulations and turned towards a first undulation of the first series of undulations, the internal face having a first end portion partially overhanging the first undulation; - and an internal metallic sealing membrane intended to be in contact with the liquefied gas, wherein the internal sealing membrane is separated from the external sealing membrane by the spacer block and includes at least one flat portion which is fixed against the inner face of the spacer block.

[0011] Thanks to these characteristics, the spacer block can be positioned above a corrugation in the external waterproof membrane. Consequently, the transmission of hydrostatic pressure forces to the underlying elements is optimal and the load-bearing capacity of the internal waterproof membrane is satisfactory.

[0012] According to one embodiment, the invention also provides a method for adapting a sealed tank initially intended for the storage of a first liquefied gas, the method comprising: fixing a spacer block on at least one flat area of ​​an external leak-proof membrane, wherein the external leak-proof membrane is a primary membrane belonging to a leak-proof tank wall for the storage of the first liquefied gas, the external leak-proof membrane being metallic and having a first series of parallel corrugations; the spacer block having an external end, a flat inner face parallel to the external end and lateral ends connecting the external end to the internal face, the external end being positioned against said at least one flat area, the lateral ends comprising a first lateral end extending parallel to the first series of undulations and turned towards a first undulation of the first series of undulations, the internal face comprising a first end portion partially overhanging the first undulation; and fix at least one flat area of ​​an internal metallic sealing membrane against the inner face of the spacer block, so that the internal sealing membrane is spaced from the external sealing membrane by the spacer block.

[0013] The use of this method makes it possible in particular to anchor the spacer block directly onto a primary membrane belonging to a sealed and thermally insulating tank wall for LNG storage, without the need to install thermal protections between the flat area of ​​the external sealed membrane and the thermally insulating barrier.

[0014] According to embodiments, such a tank or such a process may include one or more of the following characteristics.

[0015] According to one embodiment, the first lateral end develops between the outer end and the inner face of the spacer block towards the first undulation.

[0016] According to one embodiment, the flat area of ​​the external waterproof membrane is located between two corrugations of the first series of corrugations.

[0017] According to one embodiment, the first lateral end has a concave shape so as to overhang the first undulation.

[0018] Thanks to these characteristics, the first lateral end conforms remotely to the shape of the first corrugation in order to obtain good support of the internal surface of the spacer block without interacting with the corrugation of the external sealing membrane, thus allowing good support of the internal sealing membrane.

[0019] In one embodiment, the first lateral end is not in contact with the first corrugation. Thus, the first corrugation is free to open and close without its movement being hindered by contact of the spacer block against the first corrugation. In another embodiment, the lateral ends are not in contact with the corrugations of the external sealing membrane.

[0020] According to one embodiment, the spacer block is not in contact with the undulations of the external waterproof membrane.

[0021] According to one embodiment, the spacer block has a thickness less than a height of the first series of undulations in the thickness direction of the tank wall.

[0022] According to one embodiment, the spacer block has a thickness greater than a height of the first series of undulations in the thickness direction of the wall of tank.

[0023] According to one embodiment, the thickness of the spacer block is between 20 and 150 mm.

[0024] According to one embodiment, the external waterproof membrane comprises a second series of corrugations perpendicular to the first series of corrugations.

[0025] According to one embodiment, the lateral ends of the spacer block comprise a second lateral end extending parallel to the second series of undulations and turned respectively towards a first undulation of the second series of undulations, the inner face comprising a second end portion partially overhanging the first undulation of the second series of undulations.

[0026] According to one embodiment, the second lateral end develops between the outer end and the inner face of the spacer block towards the first undulation of the second series of undulations.

[0027] According to one embodiment, the flat area is defined between two undulations of the first series of undulations and two undulations of the second series of undulations.

[0028] According to one embodiment, the undulations of the external sealing membrane are salient with respect to the flat areas in the direction of the interior of the tank.

[0029] According to one embodiment, the height of the first series of corrugations is less than the height of the second series of corrugations in the thickness direction of the tank wall. According to another embodiment, the spacer block has a thickness between the height of the second series of corrugations and the height of the first series of corrugations.

[0030] According to one embodiment, the spacer block comprises support ribs located under the inner face between the lateral ends and hollow cells located between the support ribs.

[0031] Thus, the spacer block is reinforced by the support ribs. In addition, the hollow cells allow for the inerting of the internal space of the spacer block, permitting the passage of gas molecules between the hollow cells located inside the spacer block and the inter-membrane space located between the inner and outer airtight membranes.

[0032] According to one embodiment, the support ribs are parallel. According to another embodiment, the support ribs are connected to each other.

[0033] According to one embodiment, the hollow cells have, in cross-sectional view, a rectangular or triangular shape.

[0034] According to one embodiment, the outer end of the spacer block is formed by the edges of the lateral ends and / or the end edges of the support ribs, the hollow cells being open at the outer end of the spacer block.

[0035] Thus, hollow cells make it possible to achieve inerting of the internal space of the spacer block allowing the passage of gas molecules between the hollow cells located inside the spacer block and the inter-membrane space located between the inner airtight membrane and the outer airtight membrane.

[0036] According to one embodiment, a lateral end of the lateral ends is formed by lateral edges of the support ribs. According to another embodiment, the first lateral end is formed by lateral edges of the support ribs. According to another embodiment, the lateral ends are formed by the end edges of the support ribs.

[0037] According to one embodiment, the external end and the lateral ends are formed by end edges of the support ribs.

[0038] According to one embodiment, the external end of the spacer block is formed by a flat external face parallel to the internal face.

[0039] Thanks to these characteristics, the support of the internal waterproof membrane by the spacer block is improved.

[0040] According to one embodiment, at least one lateral end of the lateral ends comprises a lateral wall through which a through passage passes. According to one embodiment, the first lateral end comprises a lateral wall through which a through passage passes.

[0041] According to one embodiment, at least one lateral end of the lateral ends comprises a plurality of through passages.

[0042] According to one embodiment, a lateral end comprises a plurality of support elements spaced from each other by through passages, the support elements preferably being spacers connecting the external end and the internal face of the spacer block.

[0043] According to one embodiment, the tank further comprises a fastening piece attached to the flat area of ​​the outer sealing membrane and projecting towards the inner sealing membrane, the spacer block being attached to the fastening piece. In one embodiment, the fastening piece is selected from a metal cylinder or a metal strip. In a preferred embodiment, the fastening piece is a metal rod, for example, a metal stud.

[0044] According to one embodiment, the fastening piece is attached to the external sealing membrane by welding onto an inner face of the flat area of ​​the external sealing membrane. According to another embodiment, the fastening piece is attached via the capacitor discharge welding process.

[0045] Thus, the fastening element, such as a fixing rod, can be fixed directly onto the outer membrane, without penetrating said outer sealing membrane. This embodiment is particularly advantageous when adapting a sealed and thermally insulated tank initially intended for LNG storage, in order to store Liquid ammonia. Indeed, the capacitor discharge welding process also avoids degrading the underlying insulation with heat, without the need to add additional thermal protection.

[0046] In one embodiment, the spacer block includes a temporary through-hole for the passage and attachment of the fixing rod. In another embodiment, the spacer block includes a metal cover closing the temporary attachment hole.

[0047] According to one embodiment, the spacer block includes a retaining surface cooperating with a nut or a clip mounted on the fixing piece.

[0048] According to one embodiment, the spacer block is made of a material compatible with the liquefied gas which is intended to be contained in the tank.

[0049] According to one embodiment, the spacer block comprises aluminum or a thermoplastic material.

[0050] In one embodiment, the spacer comprises an aluminum alloy, for example, aluminum alloy 6082. In one embodiment, the spacer block comprises more than 50% aluminum by mass of the spacer. In one embodiment, the spacer block consists of aluminum.

[0051] Thanks to these characteristics, the spacer block is compatible with ammonia; that is, the spacer block is not damaged by contact with liquid or gaseous ammonia, meaning that the physical properties of the spacer block, which primarily support the internal membrane, are not altered by contact with ammonia. Consequently, thanks to these characteristics, if the internal airtight 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.

[0052] The spacer 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.

[0053] According to one embodiment, the spacer block comprises aluminum and is obtained by extrusion.

[0054] According to one embodiment, the thermoplastic material is chosen from: high-density polyethylene, polypropylene and high-impact polystyrene.

[0055] According to one embodiment, the thermoplastic spacer block comprises fibers, for example long fibers.

[0056] According to one embodiment, the composite spacer block is obtained by thermoforming or by injection.

[0057] According to one embodiment, the spacer block does not include thermally insulating materials.

[0058] According to one embodiment, the at least one flat area comprises a first flat area, the spacer block has a thickness greater than a height of the first series of corrugations in the thickness direction of the tank wall and the external end of the spacer block is disposed on at least a second flat area of ​​the external sealing membrane, the spacer block extending over at least one other corrugation of the first series of corrugations located between said first flat area and said second flat area.

[0059] According to one embodiment, the spacer block has a thickness greater than a height of the second series of corrugations in the thickness direction of the tank wall and the external end of the spacer block is disposed on at least one other flat area of ​​the external sealing membrane, the spacer block extending over another corrugation of the second series of corrugations located between said first flat area and said other flat area.

[0060] Preferably in this case, the height of the first series of undulations is less than the height of the second series of undulations in the thickness direction of the tank wall.

[0061] According to one embodiment, the outer end of the spacer block is disposed on at least one second flat area of ​​the outer waterproof membrane, the spacer block extending over at least one other corrugation of the first series of corrugations located between said first flat area and said second flat area and the outer end of the spacer block is further disposed on at least one other flat area of ​​the outer waterproof membrane, the spacer block extending over one other corrugation of the second series of corrugations located between said first flat area and said other flat area.

[0062] According to one embodiment, the external end of the spacer block is arranged on n flat areas of the external waterproof membrane, n being a number chosen between 2 and 20, and preferably chosen between 2 and 9.

[0063] According to one embodiment, the spacer block extends over a number between 2 and 9 undulations of the first series of undulations.

[0064] According to one embodiment, the spacer block extends over a number between 2 and 9 undulations of the second series of undulations.

[0065] In one embodiment, the spacer block extends over two undulations of the first series of undulations and over two undulations of the second series of undulations. In another embodiment, the spacer block extends over two undulations of the first series of undulations and over three undulations of the second series of undulations. In another embodiment, the spacer block extends over three undulations of the first series of undulations and over two undulations of the second series of undulations. In another embodiment, the block spacer extends over three undulations of the first set of undulations and over three undulations of the second set of undulations.

[0066] In one embodiment, the outer end of the spacer block comprises a portion having a shape complementary to a corrugation of the first series of corrugations and / or a shape complementary to a corrugation of the second series of corrugations, so as to pass over and at a distance from the corrugation of the first series of corrugations and / or over the second series of corrugations. In one embodiment, the complementary shape is formed by embossing the outer end of the spacer block.

[0067] According to one embodiment, the lateral ends comprise a third lateral end situated opposite the first lateral end extending parallel to the first series of undulations, the inner face comprising a third end portion partially overhanging said second undulation of the first series of undulations.

[0068] According to one embodiment, the third lateral end develops between the outer end and the inner face of the spacer block towards the second undulation of the first series of undulations.

[0069] According to one embodiment, the inner face has a larger dimension than the outer end in a direction transverse to the first series of undulations.

[0070] According to one embodiment, the lateral ends comprise a fourth lateral end situated opposite the second lateral end, the fourth lateral end developing between the outer end and the inner face of the spacer block towards a second undulation of the second series of undulations, so that the inner face comprises a fourth end portion partially overhanging said second undulation.

[0071] According to one embodiment, the internal waterproof membrane comprises a first series of corrugations parallel to the first series of corrugations of the external waterproof membrane and flat areas.

[0072] According to one embodiment, at least one corrugation of the first series of corrugations of the internal sealing membrane is opposite the first corrugation of the first series of corrugations of the external sealing membrane in the thickness direction of the tank wall.

[0073] Thus, this makes it possible in particular to obtain a tank in which the thickness of the spacer block is less than the height of the first undulations of the external membrane.

[0074] According to one embodiment, at least one corrugation of the first series of corrugations of the internal sealing membrane is offset from the first corrugation of the first series of corrugations of the external sealing membrane in the thickness direction of the tank wall.

[0075] According to one embodiment, the two feet of the corrugation of the first series of corrugations are positioned against the inner face of the spacer block.

[0076] According to one embodiment, the pitch of the corrugations of the first series of corrugations of the external sealing membrane is identical to the pitch of the corrugations of the first series of corrugations of the internal sealing membrane.

[0077] According to one embodiment, the pitch of the corrugations of the first series of corrugations of the external sealing membrane is different from the pitch of the corrugations of the first series of corrugations of the internal sealing membrane.

[0078] 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.

[0079] 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.

[0080] According to yet another embodiment, the first series of undulations and the second series of undulations have the same height.

[0081] According to one embodiment, the undulations of the internal sealing membrane are salient with respect to the flat areas in the direction of the interior of the tank.

[0082] According to one embodiment, the internal sealed membrane of the sealed tank is intended to be in contact with a liquefied gas chosen from: ammonia, butane, propane or ethane, and preferably ammonia.

[0083] According to one embodiment, an internal space of the tank delimited by the internal sealed membrane contains a liquefied gas chosen from: ammonia, butane, propane or ethane, and preferably with ammonia.

[0084] According to one embodiment, the tank wall comprises a metal insert that is fixed to the inner face of the spacer block, and the internal sealing membrane is welded to the metal insert. Further details on the geometry or fixing of the metal insert are illustrated in particular in document EP0064886A1, primarily in Figures 7 to 10, in which the insulating barrier is replaced by the spacer block.

[0085] According to one embodiment, the internal sealing membrane and the external sealing membrane are made of stainless steel.

[0086] According to one embodiment, the sealed tank is thermally insulating and the tank wall comprises at least one thermally insulating barrier arranged between the external sealed membrane and the supporting structure. For example, the thermally insulating barrier may comprise insulating elements made of various materials, including materials incompatible with ammonia such as polyurethane foam or glass wool.

[0087] Thus, when the external waterproof membrane is fixed against the thermally insulating barrier, the spacer block allows, in particular, the transmission of hydrostatic pressure forces to said thermally insulating barrier. Furthermore, the spacer block allows for a better distribution of loads on the underlying thermally insulating barrier. Indeed, when the internal waterproof membrane is subjected to a concentrated stress on a surface smaller than the surface of the spacer block, the insulating block will distribute the stress over a larger surface of the underlying thermally insulating barrier.

[0088] Furthermore, thanks to these characteristics, it is possible to achieve inerting of the inter-membrane space located between the inner and outer airtight membranes. Consequently, in the event of a gas leak from the inner airtight membrane into the inter-membrane space, it will be possible to evacuate the unwanted gas from said inter-membrane space without damaging the underlying thermally insulating barrier.

[0089] In one embodiment, the tank wall comprises an additional waterproof membrane arranged between the external waterproof membrane and the supporting structure. In another embodiment, a primary thermally insulating barrier is arranged between the additional waterproof membrane and the external waterproof membrane, and a secondary thermally insulating barrier is arranged between the additional waterproof membrane and the supporting structure. In one embodiment, the primary and / or secondary thermally insulating barrier comprises polyurethane foam or glass wool.

[0090] According to one embodiment, the tank wall comprises a plurality of spacer blocks which are each located on a respective flat area of ​​the plurality of flat areas of the external sealing membrane.

[0091] According to one embodiment, a spacer block is located on each flat area of ​​the external waterproof membrane.

[0092] According to one embodiment, each flat area of ​​the external waterproof membrane is covered by an external end of a spacer block which is disposed on it.

[0093] An external end of the same spacer block may rest on several flat areas and / or an external end of a spacer block may rest on a single flat area.

[0094] According to one embodiment, the internal space of the tank has a storage capacity of more than 70,000 m3.

[0095] According to one embodiment, the aforementioned tank wall is a bottom wall of the tank when the tank is in a position of use.

[0096] According to one embodiment, the aforementioned tank wall is a side wall of the tank when the tank is in a position of use.

[0097] According to one embodiment, the tank comprises a plurality of the aforementioned walls.

[0098] According to one embodiment, the invention also provides a storage installation of a liquefied gas comprising a supporting structure and the aforementioned sealed tank, the sealed tank being positioned and fixed against the supporting structure.

[0099] According to one embodiment of the process, the first liquefied gas is LNG.

[0100] According to one embodiment of the process, the internal waterproof membrane is intended to to be in contact with ammonia, butane, propane or ethane, preferably with ammonia.

[0101] According to one embodiment of the process, the sealed and thermally insulating tank wall for the storage of the first liquefied gas has a multilayer structure which includes successively from the outside of the tank, a secondary insulating barrier, a secondary sealed membrane, a primary insulating barrier and a primary sealed membrane.

[0102] In one embodiment, the spacer block is attached to the flat area of ​​an external waterproof membrane via a fastener welded to an inner face of the flat area of ​​the external waterproof membrane and projecting from the external waterproof membrane. The spacer block is attached to the fastener, and the weld may be performed using the capacitor discharge welding process. In one embodiment, the fastener is a metal cylinder or a metal strip. In a preferred embodiment, the fastener is a metal rod, for example, a metal stud.

[0103] Such a tank may be part of an onshore storage facility or installed in a floating structure, whether coastal or deep-water, including a liquefied gas carrier, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO), and others. Such a tank may also serve as a fuel tank in any type of vessel.

[0104] According to one embodiment, the supporting structure rests on the ground, on a seabed or is part of a ship.

[0105] According to one embodiment, an onshore installation comprises a supporting structure and the aforementioned tank disposed in the supporting structure.

[0106] 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.

[0107] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned vessel and insulated pipelines arranged to connect the vessel's tank to a floating or land-based storage facility.

[0108] According to one embodiment, the transfer system also includes a pump for driving a flow of liquefied gas through insulated pipes from or to the floating or land-based storage installation to or from the ship'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 an enlarged, cross-sectional view of zone I of [Fig. 1], representing a tank wall according to a first embodiment.

[0113] Fig. 3 represents a bottom view of a spacer block according to the first embodiment.

[0114] Fig. 4 represents a partial, exploded perspective view of a tank wall according to the first embodiment.

[0115] Fig. 5 represents a partial, cross-sectional view of a tank wall according to a second embodiment.

[0116] Fig. 6 represents a cross-sectional view of a tank wall according to a third embodiment.

[0117] Fig. 7 represents a top view of a tank wall according to a fourth embodiment.

[0118] Fig. 8 represents a partial, cross-sectional view of a corner area of ​​a tank comprising a spacer block according to a fifth embodiment.

[0119] Figure 9 shows a schematic cutaway representation of a ship's tank and a terminal for loading and unloading that tank. Description of embodiments

[0120] 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.

[0121] In relation to [Fig. 1], a watertight tank wall 1 is described in general terms below according to various embodiments. Such a wall structure can be used to construct substantially all the walls of 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 coincide necessarily with the notion of high in the Earth's gravitational field. Similarly, the terms 'under', 'below', 'lower' and 'bottom' generally refer to a position located towards the outside of the tank and therefore do not necessarily coincide with the notion of low in the Earth's gravitational field.

[0122] The wall 1 has a multilayer structure comprising, along the thickness direction E of the 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, a plurality of spacer blocks 5 and an internal sealing membrane 6 intended to be in contact with the liquefied gas such as liquid ammonia.

[0123] 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 a partition formed by the double hull of a ship.

[0124] 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.

[0125] The auxiliary barrier 2 may further comprise a secondary flexible membrane made of composite material (not shown) bonded against the thermally insulating panels.

[0126] The auxiliary barrier 2 may further comprise a second layer of thermally insulating panels bonded against the secondary flexible membrane.

[0127] The external sealing membrane 4 is metallic, preferably made of 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.

[0128] Similarly, 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.

[0129] 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.

[0130] Tank walls according to several embodiments will be described in more detail below.

[0131] In Figures 2 to 4, the elements identical or similar to those in [Fig. 1] bear the same reference numerals incremented by 100.

[0132] In relation to figures 2 to 4, a first variant of a sealed tank wall 101 for the storage of liquefied gas such as ammonia is described below.

[0133] The tank wall 101 comprises an external watertight membrane 104 having a series of small parallel corrugations 114 and further comprising a series of large corrugations 118 perpendicular to the small corrugations 114. The large corrugations 118 and the small corrugations 114 project towards the interior of the tank. The large corrugations 118 have a height greater than the height of the small corrugations 114.

[0134] Plane areas 115 are defined between the small undulations 114 and between the large undulations 118.

[0135] A spacer block 105 is located on the flat area 115 of the external sealing membrane 104, as can be seen for example in figures 2 and 4. The thickness of the spacer block 105 is here between the height of the small corrugations 114 and the height of the large corrugations 118.

[0136] 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.

[0137] 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 114 and the large corrugations 118. 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.

[0138] The four lateral ends develop between the outer end 130 and the inner face 131 of the spacer block 105 and comprise: two lateral ends 132 facing each other and extending parallel to the small undulations 114, i.e. in the longitudinal direction of the small undulations 114, and two second lateral ends 133 facing each other and extending parallel to the large undulations 118, i.e. in the longitudinal direction of the large undulations 118. The lateral ends do not touch said undulations.

[0139] The two lateral ends 132 are turned respectively towards two small corrugations 114 without touching the two small corrugations 114. 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 114, i.e., in a direction parallel to the large corrugations 118, so that two opposite end portions of the inner face 132 each partially overhang the adjacent small corrugation 114 and support a foot of a corrugation 116 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 undulation 114.

[0140] The spacer block 105 further comprises a plurality of support ribs 134 which form hollow cells 135. The hollow cells 135 have the shape of a plurality of aligned rectangular compartments. The plurality of support 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.

[0141] The spacer block 105 has a temporary orifice 121 which goes through the thickness of the spacer block 105, and in the middle of the spacer block 105, in order to allow the spacer block 105 to be fixed against the flat area 115.

[0142] The spacer block 105 is fixed against said flat area 115 via a screw-nut system, visible in [Fig.4]. Other fixing systems may also be used.

[0143] To secure the spacer block 105, a threaded rod 120 is welded to the flat area 115 of the external sealing membrane 104, for example, using capacitor discharge welding, so that the threaded rod 120 protrudes upwards, i.e., towards the inside of the tank. The spacer block 105 is then positioned on the flat area 115 by inserting the threaded rod 120 into the temporary opening 121. The spacer block 105 is then secured by means of a retaining surface cooperating with a nut 122.

[0144] After fixing the spacer block 105 against the flat area 115, the temporary opening 121 is closed by a metal cover 123 so that the inner face 131 is flat in order to best support the internal sealing membrane 106. The metal cover is for example made of aluminum or stainless steel.

[0145] The flat area 117 of the internal sealing membrane 106 rests against the flat inner face 131 and is fixed to the spacer block 105. The fixing is achieved, for example, by welding onto a metal insert positioned on the inner face 131. The metal insert is, for example, the metal cover 123, which is fixed against a fixing portion 119 on the flat inner face 131. It should be noted that the metal insert can also be positioned in other locations on the inner face 131.

[0146] Figure 5 illustrates an alternative embodiment of the spacer block. In Figure 5, the elements identical or similar to those in Figures 2 to 4 bear the same reference numerals incremented by 100.

[0147] The spacer block 205 differs from the spacer block of Figures 2 to 4 in that the two facing lateral ends 232 have a greater curvature. In addition, the through-hole 221 has a different shape and includes a retaining surface 224 cooperating with a threaded rod 220 and a nut 222 mounted on the threaded rod 220. The spacer block 205 comprises fewer ribs of support 234 and therefore of hollow cells 235.

[0148] The spacer blocks described above cover a single flat area of ​​the external waterproof membrane. However, a spacer block can have larger dimensions, particularly so as to cover several flat areas.

[0149] Figures 6 and 7 illustrate two alternative embodiments of the spacer block covering several planar areas. In Figures 6 and 7, the elements identical or similar to those in Figures 2 to 4 bear the same reference numerals incremented by 200.

[0150] The spacer block 305 of [Fig. 6] differs from the spacer block of Figures 2 to 4 in that the spacer block 305 is positioned on two adjacent flat areas 315 of the outer sealing membrane 304 separated by a small corrugation 314. Each flat area is delimited by two adjacent large corrugations 318 and two adjacent small corrugations 314. The outer end 330 of the spacer block 305 has two flat portions, each positioned on a flat area 315. The outer end 330 of the spacer block 305 further has a connecting portion 340 that links the two flat portions. The connecting portion 340 extends over the small undulation 314. In other words, the connecting portion 340 forms a tunnel through which the small undulation 114 passes, over the entire dimension of the spacer block 305.

[0151] The spacer block 305 of [Fig. 7] has a thickness greater than the height of the large corrugations 118. The outer end 330 of the spacer block 305 has four flat portions, each positioned on a flat area 315. The outer end 330 of the spacer block 305 also has connecting portions that link the four portions of the outer end 330. The connecting portions extend over a small corrugation 314 or a large corrugation 318. In other words, a first connecting portion 340 of the spacer block 305 forms a tunnel through which the large corrugation 118 passes, along the entire length of the spacer block 305. A second connecting portion 341 forms a tunnel through which the small corrugation 314 passes, along the entire width of the spacer block 305. The inner face 331 of the spacer block has a greater dimension that the outer end 330. Each of the four edges of the inner face 331 partially overhangs a corrugation.

[0152] Figure 8 illustrates an alternative embodiment of the spacer block. In Figure 8, the elements identical or similar to those in Figures 2 to 4 bear the same reference numerals incremented by 300.

[0153] The two spacer blocks 405 of [Fig. 8] differ from the spacer block of Figures 2 to 4 in that they are located at a corner of the tank. The flat areas 415 of the external sealing membranes 414 are located between a corrugation 414 and the corner of the tank.

[0154] The spacer blocks 405 are each positioned on a flat area 415, at the corner, and each have a beveled lateral end 432b located on the opposite side. of the lateral end 432. The beveled lateral ends 432b of the spacer blocks 405 are positioned butted against each other. Figure 8 illustrates a 90° tub angle with the beveled lateral ends 432b at 45°, but such an arrangement can be adapted to be positioned at another tub angle, such as a 135° angle, for example. Furthermore, the two beveled lateral ends 432b can have different bevel angles, as long as their union forms an angle corresponding to the tub angle.

[0155] According to one embodiment, the tank wall described above can be obtained from a pre-existing sealed and thermally insulated tank wall for LNG storage, into which the spacer blocks 5, 105, or 205 and the internal sealing membrane 6, 106, 206 have been installed. Numerous prior art designs exist for sealed and thermally insulated tank walls for LNG storage. According to one embodiment, the sealed and thermally insulated tank wall for LNG storage conforms to publications FR2739675 or WO2022200539. Further details regarding the auxiliary barrier 2 and the external sealing membrane 4, 104, 204 can be found in these publications.

[0156] With reference to [Fig. 9], 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.

[0157] 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.

[0158] Figure 9 also shows 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 that supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 that can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 accommodates all ship sizes. A connecting pipeline (not shown) extends inside the tower 78. The loading and unloading berth 75 allows the ship 70 to be loaded and unloaded from or to the onshore facility 77. The latter comprises 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 facility 77 over a large distance, for example 5 km, which allows the ship 70 to be kept a large distance from the coast during loading and unloading operations.

[0159] To generate the pressure necessary for the transfer of the liquefied gas, one can either use pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 or allow a rise in pressure in the internal space of the tank under the effect of the evaporation of the liquefied gas stored in the tank.

[0160] 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.

[0161] The use of the verb "comporter" or "comprendre" and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0162] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. Leak-proof tank for the storage of a liquefied gas, the leak-proof tank comprising a tank wall (1, 101, 201, 301, 401) intended to be installed in a supporting structure (3), the tank wall comprising along a thickness direction (E) of the tank wall: - an external metallic leak-proof membrane (4, 104, 204, 304, 404) comprising a first series of parallel corrugations (14, 114, 214, 314, 414) and flat areas (15, 115, 215, 315, 415);- a spacer block (5, 105, 205, 305, 405) disposed on at least one of said flat areas (15, 115, 215, 315, 415) of the external waterproof membrane and fixed to the external waterproof membrane, the spacer block having an external end (130, 230, 330, 430), a flat internal face (131, 231, 331, 431) parallel to the external end and lateral ends (132, 133, 232, 332, 432) connecting the external end to the internal face, the external end being positioned against said at least one flat area, the lateral ends having a first lateral end (132, 232, 332, 432) extending parallel to the first series of corrugations (14, 114, 214, 314, 414) and turned towards a first undulation of the first series of undulations, the inner face having a first portion of end partially overhanging the first undulation;- and an internal metallic sealing membrane (6, 106, 206, 306) intended to be in contact with the liquefied gas, in which the internal sealing membrane is separated from the external sealing membrane by the spacer block and includes at least one flat portion (17, 117, 317) which is fixed against the inner face of the spacer block.

2. Watertight tank according to claim 1, wherein said first lateral end has a concave shape so as to overhang the first corrugation.

3. Watertight tank according to claim 1 or 2, wherein the first lateral end is not in contact with the first corrugation.

4. A watertight tank according to any one of claims 1 to 3, wherein said at least one flat zone comprises a first flat zone and wherein the spacer block has a thickness greater than a height of the first series of corrugations in the thickness direction of the tank wall and wherein the outer end of the spacer block is disposed on at least a second flat zone (15, 115, 215, 315, 415) of the external waterproof membrane, the spacer block extending over at least one other corrugation (14, 114, 214, 314, 414) of the first series of corrugations located between said first flat zone and said second flat zone.

5. Watertight tank according to any one of claims 1 to 4, wherein the outer watertight membrane comprises a second series of corrugations (118, 218, 318) perpendicular to the first series of corrugations, wherein the lateral ends comprise a second lateral end (133, 333) extending parallel to the second series of corrugations and turned towards a first corrugation of the second series of corrugations, the inner face comprising a second end portion partially overhanging the first corrugation of the second series of corrugations.

6. Watertight tank according to claim 5, wherein a height of the first series of corrugations is less than a height of the second series of corrugations in the thickness direction (E) of the tank wall, wherein the spacer block has a thickness between the height of the second series of corrugations and the height of the first series of corrugations.

7. Watertight tank according to claim 5, wherein the spacer block has a thickness greater than a height of the second series of corrugations in the thickness direction of the tank wall and wherein the outer end of the spacer block is disposed on at least one other flat area (15, 115, 215, 315, 415) of the external watertight membrane, the spacer block extending over another corrugation (118, 218, 318) of the second series of corrugations located between said first flat area and said other flat area.

8. A watertight tank according to any one of claims 1 to 7, wherein the lateral ends comprise a third lateral end (132, 232, 332, 432) situated opposite the first lateral end extending parallel to the first series of corrugations, the inner face comprising a third end portion partially overhanging said second corrugation of the first series of corrugations, the inner face (131, 231) having a larger dimension than the outer end (130, 230) in a direction transverse to the first series of corrugations.

9. A watertight tank according to any one of claims 1 to 8, wherein the spacer block has support ribs (134, 234) located under the inner face between the lateral extremities and hollow cells (135, 235) located between the supporting ribs.

10. A sealed tank according to claim 9, wherein the outer end of the spacer block is formed by edges of the lateral ends and / or end edges of the support ribs, the hollow cells being open at the outer end of the spacer block.

11. Watertight tank according to claim 9 or 10, wherein the first lateral end is formed by lateral edges of the support ribs.

12. Watertight tank according to any one of claims 1 to 11, further comprising a fixing piece (120, 220) fixed to the flat area of ​​the external watertight membrane and projecting towards the internal watertight membrane, the spacer block being fixed to the fixing piece.

13. Watertight tank according to claim 12, in which the spacer block has a retaining surface (224) cooperating with a nut (122, 222) or a clip mounted on the fixing piece (120, 220).

14. A sealed tank according to any one of claims 1 to 13, wherein the spacer block comprises aluminum or a thermoplastic material.

15. Watertight tank according to any one of claims 1 to 14, wherein the internal watertight membrane comprises a first series of corrugations (16, 116, 216, 316) parallel to the first series of corrugations of the external watertight membrane and flat areas (17, 117), at least one corrugation of the first series of corrugations of the internal watertight membrane being opposite the first corrugation of the first series of corrugations of the external watertight membrane in the thickness direction of the tank wall.

16. Method for adapting a sealed tank initially intended for the storage of a first liquefied gas, the method comprising: fixing a spacer block (5, 105, 205, 305, 405) on at least one flat area (15, 115, 215, 315, 415) of an external sealed membrane (4, 104, 204, 304, 404), wherein the external sealed membrane is a primary membrane belonging to a sealed tank wall (1, 101, 201, 301, 401) for the storage of the first liquefied gas, the external sealed membrane being metallic and comprising a first series of parallel corrugations (14, 114, 214, 314, 414); the spacer block having an external end (130, 230, 330, 430), a flat internal face (131, 231, 331, 431) parallel to the external end and lateral ends (132, 133, 232, 332, 432) connecting the external end to the inner face, the outer end being positioned against said at least one flat area, the lateral ends having a first lateral end (132, 232, 332, 432) extending parallel to the first series of corrugations and turned towards a first corrugation of the first series of corrugations, the inner face having a first end portion partially overhanging the first corrugation; and fixing at least one flat area (17, 117, 317) of an internal metallic sealing membrane (6, 106, 206, 306) against the inner face of the spacer block, so that the internal sealing membrane is spaced from the external sealing membrane by the spacer block.

17. Land installation comprising a supporting structure and a tank according to any one of claims 1 to 15 disposed in the supporting structure.

18. 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 15 disposed in the double hull.

19. Transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 18 and insulated pipelines (73, 79, 76, 81) arranged to connect the vessel's tank (71) to a floating or land-based storage facility (77).

20. A method of loading or unloading a ship (70) according to claim 18, 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).

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