Wall for a leaktight and thermally insulating vessel

Abstract

The invention relates to a wall (11) for a leaktight and thermally insulating vessel for storing a liquefied gas, said wall (11) comprising, in succession in a thickness direction from the outside to the inside of the vessel, a leaktight outer barrier (13), a thermally insulating barrier (14) and a leaktight inner barrier (15), the thermally insulating barrier (14) having a gas phase at an absolute pressure of less than 1 Pa and comprising: - a radiative multilayer insulation cover (47) which extends at right angles to the thickness direction, said radiative multilayer insulation cover (47) comprising a stack of a plurality of sheets which are made of metal or polymer material coated with a metal and which are separated from one another by a textile layer; and - insulating elements (51) which have an open-celled porous structure and are arranged between the radiative multilayer insulation cover (47) and the leaktight outer barrier (13).

Description

Wall for a waterproof and thermally insulating tank

[0001] The invention relates to the field of sealed and thermally insulating tanks. In particular, the invention relates to the field of sealed and thermally insulating tanks for the storage and / or transport of a liquefied gas, such as liquid hydrogen which is at approximately -253°C at atmospheric pressure. Technological background

[0002] In the state of the art, tanks intended for the storage of liquid hydrogen are known, this liquefied gas having the particularity of having a liquefaction temperature even lower than that of liquefied natural gas. Thus, in order to limit the evaporation rate of liquid hydrogen, these tanks must have even better thermal insulation performance than those of tanks intended for the storage of liquefied natural gas.

[0003] Document CN113739061A discloses a tank for storing liquid hydrogen. The tank comprises an outer tank, an inner tank, and a multi-layer structure that rests against the inner tank and includes, from the outside to the inside, a secondary thermally insulating barrier resting against the inner tank, a secondary sealed membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealed membrane, and a primary sealed membrane resting against the primary thermally insulating barrier.

[0004] In order to further improve the thermal insulation performance of the tank, the space between the outer tank and the inner tank is placed under vacuum, for example at an absolute pressure of around 10 -3Pa. In addition, a composite reflective screen comprising in particular a plurality of aluminum sheets is arranged against the outer face of the inner tank and thus makes it possible to reduce heat transfer by thermal radiation from the outside to the inside of the tank.

[0005] Such a liquid hydrogen storage tank is not entirely satisfactory. Indeed, in the event of a loss of tightness in one of the inner or outer tanks likely to degrade the vacuum level in the space between these two tanks, the thermal insulation performance of the liquid hydrogen storage tank risks being very significantly degraded.

[0006] In addition, the composite reflective screen is positioned in a space which remains subject to high temperatures, and consequently to a significant radiation flux, which limits its effectiveness.

[0007] Finally, the aforementioned storage tank has a complex structure since, in addition to the multi-layer structure comprising two thermally insulating barriers and two sealing membranes, it includes a space placed in depression between the inner tank and the outer tank. Summary

[0008] An idea underlying the invention is to propose a wall for a sealed and thermally insulating tank having improved thermal insulation properties even under degraded conditions, such as a loss of sealing of one of the sealed barriers.

[0009] According to one embodiment, the invention provides a wall for a sealed and thermally insulating tank for storing a liquefied gas, said wall successively comprising, in a thickness direction, from the outside to the inside of the tank, an external sealed barrier, a thermally insulating barrier and an internal sealed barrier, the thermally insulating barrier having a gas phase at an absolute pressure of less than 1 Pa and comprising: - a radiative multilayer insulation blanket which extends orthogonally to the thickness direction, said radiative multilayer insulation blanket comprising a stack of a plurality of sheets of metal or polymer material coated with a metal and separated from each other by a textile layer; and - insulating elements having a porous structure with open cells which are arranged between the radiative multilayer insulation blanket and the external sealed barrier.

[0010] Thus, the structure of the aforementioned thermally insulating barrier gives it excellent thermal insulation properties, even in degraded vacuum conditions. Indeed, the insulating elements make it possible to limit the heat flows through the thermally insulating barrier, in particular when the pressure inside it is higher than the prescribed pressure values. In addition, the insulating elements make it possible to further reduce the temperature of the area of ​​the thermally insulating barrier in which the radiative multilayer insulation blanket is positioned, which increases its efficiency. In addition, the insulating elements also make it possible to limit the heat flows by convection through the thermally insulating barrier.Finally, the depression is produced directly in the gas phase of the thermally insulating barrier and not within a space of an insulating element covered with a sealed envelope, which makes it possible to do without such a sealed envelope which could constitute conductive thermal bridges.

[0011] An "insulating element with a porous open-cell structure" means a thermal insulation material or component comprising empty cavities, also called cells, interconnected with each other and with the exterior.

[0012] According to embodiments, such a wall may comprise one or more of the following characteristics.

[0013] According to one embodiment, the radiative multilayer insulation cover is made of an MLI type material, MLI being the acronym for the term “Multilayer insulation” in English.

[0014] According to one embodiment, the thermally insulating barrier has a gas phase at an absolute pressure of less than 10 -1 Pa, preferably less than 10 –2 Pa and for example of the order of 10 –3 Pa. This further increases the thermal insulation performance of the thermally insulating barrier.

[0015] According to one embodiment, the internal sealed barrier is intended to be in contact with the liquefied gas contained in the tank. This makes it possible to optimize the effectiveness of the radiative multi-layer insulation blanket since it is thus exposed to the coldest temperatures. In other words, since the multi-layer insulation blanket is positioned on the coldest side of the temperature gradient, the emissivity of each of its layers is reduced.

[0016] According to one embodiment, the cumulative volumes of the cells of the insulating element occupy at least 85%, preferably more than 90%, and even more preferably more than 95% of the volume of the insulating element.

[0017] According to one embodiment, the thermal conductivity of the insulating element, when the insulating element is placed under negative air pressure relative to the reference pressure of 1 bar absolute at 20°C, is less than or equal to 10 mW.m - 1 .K -1 , preferably less than or equal to 6 mW.m -1 .K -1 .

[0018] According to one embodiment, the average size of the cells, or empty cavities, of the insulating element is less than or equal to 3 mm, and preferably less than or equal to 1 mm.

[0019] According to one embodiment, the insulating elements are chosen from glass wool, rock wool, polyester wadding, open-cell polymer foams, such as open-cell polyurethane foam, and melamine foam.

[0020] According to one embodiment, the radiative multi-layer insulation blanket is positioned in a plane that is closer to the internal sealed barrier than to the external sealed barrier. This makes it possible to further optimize the effectiveness of the radiative multi-layer insulation blanket since such positioning of the radiative multi-layer insulation blanket ensures that a majority of the elements exposed to temperatures higher than that of the internal sealed barrier do not emit radiative flux directly onto the internal sealed barrier.

[0021] According to one embodiment, the primary thermally insulating barrier comprises several radiative multilayer insulation blankets which each extend orthogonally to the thickness direction, each said radiative multilayer insulation blanket comprising a stack of a plurality of sheets of metal or polymer material coated with a metal and separated from each other by a textile layer.

[0022] According to one embodiment, the primary thermally insulating barrier comprises two radiative multi-layer insulation blankets which are preferably spaced apart by a distance of between 30 and 160 mm.

[0023] According to one embodiment, the textile layer of the radiative multilayer insulation blanket is made with fibers chosen from polymer fibers, such as polyester fibers, and glass fibers.

[0024] According to one embodiment, the metal or metal-coated polymer material sheets are made of a material chosen from aluminum, silver, aluminum-coated polymer materials and silver-coated polymer materials.

[0025] According to one embodiment, the polymer material coated with aluminum or silver is chosen from Polyimide or poly(ethylene terephthalate).

[0026] According to one embodiment, the gas phase of the primary thermally insulating barrier comprises, when the primary thermally insulating barrier is conditioned at ambient temperature, more than 50% by volume, and advantageously more than 75% by volume of an inert gas having a solid condensation temperature higher than the liquefaction temperature of the liquefied gas intended to be stored in the tank. This makes it possible to use the cryopumping phenomenon to contribute to reducing the pressure inside the primary thermally insulating barrier, in particular when the liquefied gas stored in the tank is liquid hydrogen.

[0027] According to one embodiment, the inert gas is carbon dioxide.

[0028] According to one embodiment, the thermally insulating barrier comprises load-bearing elements which rise in the thickness direction between the external sealed barrier and the internal sealed barrier, the radiative multi-layer insulation cover having openings through which the load-bearing elements pass.

[0029] According to one embodiment, the thermally insulating barrier further comprises at least one retention member which is fixed to the load-bearing elements so as to limit the movement of the insulating elements towards the internal sealed barrier.

[0030] According to one embodiment, the at least one retention member comprises a textile retention layer which is fixed to the load-bearing elements and which is arranged between the insulating elements and the radiative multi-layer insulation blanket.

[0031] According to one embodiment, the radiant multi-layer insulation blanket is fixed on the textile retention layer, which allows reliable positioning of said radiant multi-layer insulation blanket in the thermally insulating barrier.

[0032] According to one embodiment, the textile retention layer is made with fibers chosen from polymer fibers, such as polyester fibers, and glass fibers.

[0033] According to one embodiment, the insulating elements have a thickness less than a distance along the thickness direction between the external sealed barrier and the radiative multilayer insulation cover.

[0034] According to one embodiment, the internal waterproof barrier is a primary waterproof membrane intended to be in contact with the liquefied gas contained in the tank, the thermally insulating barrier is a primary thermally insulating barrier and the external waterproof barrier is a secondary waterproof membrane, the wall further comprising a secondary thermally insulating barrier resting against a supporting structure and against which the secondary waterproof membrane rests.

[0035] In an embodiment in which the thermally insulating barrier comprises several radiative multi-layer insulation blankets, the porous structure insulating elements are advantageously arranged between the outermost radiative multi-layer insulation blanket and the secondary sealing membrane.

[0036] According to one embodiment, the primary waterproofing membrane comprises a first series of corrugations having first corrugations parallel to each other and a second series of corrugations having second corrugations parallel to each other and perpendicular to the first corrugations, the primary waterproofing membrane comprising a plurality of flat zones which are each defined between two adjacent first corrugations and between two adjacent second corrugations; the primary thermally insulating barrier comprising at least a first row of load-bearing elements successively comprising, in a direction parallel to the first corrugations, at least a first, a second and a third load-bearing element which are fixed to the secondary thermally insulating barrier and which rise in the thickness direction, the first, the second and the third load-bearing elements being respectively fixed to a first,a second and a third internal tray, the plurality of flat zones successively comprising, in the direction parallel to the first corrugations, a first, a second and a third flat zones which are respectively welded in abutment against the first, the second and the third internal trays. Thanks to these characteristics, the three aforementioned supporting elements form three discrete support structures which are not rigidly connected to each other and which each support a flat zone of the primary waterproofing membrane. This allows a good distribution of the stresses between the corrugations of the primary waterproofing membrane and more particularly between the corrugations arranged on either side of the first, second and third aforementioned flat zones.,

[0037] The adverb "successively" means "one after the other, one following the other". Thus, "a first row of load-bearing elements comprising successively, in a direction parallel to the first undulations, at least a first, a second and a third load-bearing element" means that no other load-bearing element of said first row is interposed between the first and second load-bearing elements and between the second and third load-bearing elements. Similarly, "the plurality of flat areas comprising successively, in the direction parallel to the first undulations, a first, a second and a third flat areas" means that no other flat area is interposed between the first and second flat areas and between the second and third flat areas.

[0038] According to one embodiment, the first flat zone and the second flat zone are separated from each other by a second corrugation which is arranged opposite, in the thickness direction, a free space separating the first and second internal plates, the second and third flat zones being separated by a second corrugation which is arranged opposite, in the thickness direction, a free space separating the second and third external plates.

[0039] According to one embodiment, the first, second and third internal plates are respectively in contact against more than 70%, and advantageously between 90 and 100%, of the surface of the first, second and third flat zones. This makes it possible to distribute the forces due to the hydrostatic and dynamic pressures exerted by the liquefied gas on the primary waterproofing membrane over a larger support surface, thus contributing to a better distribution of the stresses.

[0040] According to one embodiment, the primary waterproofing membrane comprises a plurality of corrugated metal sheets, each corrugated metal sheet having edges that are each lap welded to an edge of an adjacent corrugated metal sheet, the first, second and third planar areas being formed by two edges of two adjacent corrugated metal sheets. In other words, the first, second and third internal trays support and anchor the two adjacent edges of two adjacent corrugated metal sheets.

[0041] According to one embodiment, the first, second and third planar areas are respectively welded by spot welding to the first, second and third internal plates.

[0042] According to one embodiment, the primary thermally insulating barrier comprises at least a second row of load-bearing elements comprising a fourth, a fifth and a sixth load-bearing elements which are fixed to the secondary thermally insulating barrier and which rise in the thickness direction of the wall, the fourth, the fifth and the sixth load-bearing elements being aligned in a direction parallel to the first corrugations and being respectively fixed to a fourth, a fifth and a sixth internal plates, the fourth, the fifth and the sixth load-bearing elements being respectively aligned in a direction parallel to the second corrugations with the first, the second and the third load-bearing elements, the plurality of flat zones comprising a fourth, a fifth and a sixth flat zones which are respectively in abutment against the fourth, the fifth and the sixth internal plates.Thus, the primary thermally insulating barrier comprises both load-bearing elements which are aligned parallel to the first corrugations of the primary waterproofing membrane and load-bearing elements which are aligned parallel to the second corrugations of the primary waterproofing membrane.

[0043] According to one embodiment, the fourth, fifth and sixth flat areas are respectively welded to the fourth, fifth and sixth internal plates.

[0044] According to one embodiment, the fourth, fifth and sixth flat areas are each separated from one of the edges of the corrugated metal sheet to which they belong by at least a first and a second corrugation. In other words, the flat areas of the primary waterproofing membrane are also welded to the internal plates outside the edges of the corrugated metal sheets, which further improves the distribution of stresses on the corrugations of the primary waterproofing membrane.

[0045] According to one embodiment, the fourth, fifth and sixth flat areas are respectively welded transparently to the fourth, fifth and sixth internal plates.

[0046] According to one embodiment, each flat area of ​​the primary waterproofing membrane bears against a respective internal plate, each of said internal plates being fixed to a respective supporting element which is fixed to the secondary thermally insulating barrier and which rises in the thickness direction. This makes it possible to ensure the homogeneity of the distribution of stresses on the corrugations of the entire primary waterproofing membrane.

[0047] According to one embodiment, each of the first, second and third supporting elements is respectively fixed to a first, a second and a third external tray, each of the first, second and third external trays being fixed to the secondary thermally insulating barrier and pressing the secondary sealing membrane against the secondary thermally insulating barrier. Thus, the external trays have a dual functionality. On the one hand, they ensure the anchoring of the supporting elements to the secondary thermally insulating barrier and, on the other hand, they prevent the secondary sealing membrane from tearing off, in particular when the pressure prevailing in the secondary thermally insulating barrier is greater than that prevailing in the primary thermally insulating barrier.

[0048] According to one embodiment, the secondary waterproofing membrane comprises a first series of corrugations having first corrugations parallel to each other and a second series of corrugations having second corrugations parallel to each other and perpendicular to the first corrugations, the secondary waterproofing membrane comprising a plurality of flat areas which are each defined between two adjacent first corrugations and between two adjacent second corrugations of the secondary waterproofing membrane, the first, second and third external plates each being pressed against one of the flat areas of the secondary waterproofing membrane.

[0049] According to one embodiment, the first, second and third external plates are respectively in contact against more than 70%, and advantageously between 90 and 100%, of the surface of the corresponding flat area of ​​the secondary waterproofing membrane. This makes it possible to distribute the forces passing through the load-bearing elements over a larger surface area of ​​the secondary waterproofing membrane, thus contributing to a better distribution of the stresses.

[0050] According to one embodiment, the first series of undulations and the second series of undulations of the secondary waterproofing membrane are respectively opposite, in the thickness direction, the first series of undulations and the second series of undulations of the primary waterproofing membrane.

[0051] According to one embodiment, the first, second and third external plates are respectively fixed to the first, second and third supporting elements by riveting.

[0052] According to one embodiment, each of the first, second and third outer plates is fixed to the secondary thermally insulating barrier by means of a primary anchoring device comprising a stud which is fixed to an insulating panel of the secondary thermally insulating barrier and which passes through an orifice of the secondary sealing membrane and an orifice provided in one of the first, second and third outer plates, the stud having a radially extending collar which is welded to the secondary sealing membrane all around said orifice of the secondary sealing membrane, the primary anchoring device further comprising a nut which is screwed onto the stud and which holds said first, second or third outer plate against the secondary sealing membrane.

[0053] According to one embodiment, the aforementioned supporting elements, in particular the first, second and third aforementioned supporting elements, each comprise an external base, an internal base and a pillar, each of the external and internal bases having a sleeve cooperating by fitting with one of the ends of the pillar and a support collar extending radially from one end of the sleeve.

[0054] According to one embodiment, each end of the pillars is fitted inside one of the sleeves. According to another variant, each sleeve is fitted inside one of the ends of one of the pillars.

[0055] According to another embodiment, the pillar, the external base and the internal base are formed from a single piece.

[0056] According to one embodiment, the support collar of the internal base is supported and fixed against one of the internal plates.

[0057] According to one embodiment, the support collar of the external base is supported and fixed against one of the external plates.

[0058] According to one embodiment, each pillar is fixed, for example by gluing, to the internal base and to the external base.

[0059] According to one embodiment, each pillar is made of a composite material comprising fibers and a matrix, which makes it possible to obtain satisfactory compressive strength for a limited conductive section.

[0060] According to one embodiment, the fibers are chosen from glass fibers, carbon fibers, aramid fibers, flax fibers, basalt fibers and mixtures thereof.

[0061] According to one embodiment, the matrix is ​​selected from polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyoxymethylene, polyetherimide, polyacrylate, copolymers thereof, polyester, vinylester, epoxy and polyurethane.

[0062] According to a preferred embodiment, the pillars are made of an epoxy resin reinforced with glass fibers.

[0063] According to one embodiment, each pillar has a tubular section.

[0064] According to one embodiment, the pillar is at least partially coated with a radiative insulation coating which surrounds said pillar.

[0065] According to one embodiment, the radiative insulation coating extends at least from an inner end of the pillar to a radiative multi-layer insulation blanket extending orthogonally to the thickness direction of the wall.

[0066] According to one embodiment, the radiative insulation coating is chosen from the materials designated by the acronym SLI for "Single Layer Insulation" in English which comprises, for example, a sheet of polymer material, such as Polyimide, or polyethylene, coated with a metal, such as aluminum, the materials designated by the acronym MLI and described previously and a previously deposited layer comprising a binder and aluminum particles.

[0067] According to one embodiment, each pillar has one or more through orifices opening into an internal space of said pillar.

[0068] According to one embodiment, each pillar has an internal space which is filled with an insulating filling made of open-cell porous material, for example chosen from an open-cell insulating polymer foam, such as open-cell polyurethane foam, glass wool, rock wool, polyester wadding, polymer aerogels, such as polyurethane-based aerogel, notably marketed under the brand name Slentite ®, and silica aerogels.

[0069] According to an alternative or complementary embodiment, each pillar has an internal space lined with a multi-layer radiative insulation cover made from a material designated by the acronym MLI for “multi-layer insulation” in English.

[0070] According to one embodiment, the primary waterproofing membrane comprises two layers of corrugated metal sheets superimposed on each other, with spacer elements being interposed between the two layers.

[0071] According to one embodiment, the primary waterproofing membrane has an additional space which is interposed between the two layers of the primary waterproofing membrane.

[0072] According to one embodiment, the additional space is placed in depression.

[0073] According to another embodiment, the additional space is connected to an inerting device comprising an inert gas tank, preferably storing helium.

[0074] According to one embodiment, the secondary thermally insulating barrier comprises insulating panels anchored to the supporting structure.

[0075] According to one embodiment, each insulating panel comprises a layer of insulating polymer foam sandwiched between an internal plate and an external plate, for example made of plywood or made from a polymer matrix reinforced by fibers, such as glass fibers.

[0076] According to one embodiment, the internal plate of the insulating panels is equipped with metal plates intended for anchoring the edges of the corrugated metal sheets of the secondary waterproofing membrane on the insulating panels.

[0077] According to one embodiment, the secondary waterproofing membrane comprises a first series of corrugations having first parallel corrugations and a second series of corrugations having second parallel corrugations.

[0078] According to one embodiment, the first and second corrugations of the secondary waterproofing membrane project outwards, towards the supporting structure, the insulating panels of the secondary thermally insulating barrier having an internal face equipped with two series of grooves perpendicular to each other and in which the first and second corrugations of the secondary waterproofing membrane are respectively housed.

[0079] According to another embodiment, the first and second corrugations of the secondary waterproofing membrane project inwardly, in the direction opposite the supporting structure.

[0080] According to one embodiment, the insulating panels of the secondary thermally insulating barrier have relaxation slots opening onto an internal face of said insulating panels and each arranged opposite one of the first or second corrugations of the secondary sealing membrane.

[0081] According to another embodiment, the external waterproof barrier and the internal waterproof barrier are self-supporting barriers connected to each other by spacer structures.

[0082] According to one embodiment, the invention also relates to a sealed and thermally insulating tank comprising a plurality of walls of the aforementioned type.

[0083] In one embodiment, the liquefied gas is liquid hydrogen.

[0084] The tank can be made using different techniques, notably in the form of an integrated membrane tank.

[0085] Such a tank may be part of a land-based storage facility or installed in a floating, coastal, or deep-water structure, including a liquid hydrogen transport vessel, i.e., a hydrogen 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.

[0086] According to one embodiment, a ship for transporting liquefied gas comprises a double hull and a aforementioned tank arranged in the double hull.

[0087] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned vessel and insulated pipes arranged so as to connect the tank installed in the hull of the vessel to a floating or land-based storage installation.

[0088] According to one embodiment, the transfer system comprises a pump for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank.

[0089] According to one embodiment, the invention also provides a method of loading or unloading such a vessel, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the vessel's tank. Brief description of the figures

[0090] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0091] This is a schematic, cutaway perspective view of a supporting structure designed to support a sealed, thermally insulating tank for storing liquefied gas.

[0092] This is a partial perspective view of a wall of a sealed and thermally insulating tank according to a first embodiment.

[0093] This is a perspective view showing the secondary thermally insulating barrier of the wall of the.

[0094] This is a perspective view showing the secondary thermally insulating barrier and the secondary waterproofing membrane of the wall of the.

[0095] This is a partial sectional view of the secondary thermally insulating barrier of the wall of the, partially illustrating an anchoring device intended to ensure the fixing of a load-bearing element of the primary thermally insulating barrier on the secondary thermally insulating barrier.

[0096] This is a cutaway view illustrating the secondary thermally insulating barrier, the secondary waterproofing membrane and load-bearing elements of the primary thermally insulating barrier of the wall of the.

[0097] This is a partial perspective view of the wall illustrating the secondary thermally insulating barrier, the secondary waterproofing membrane and the load-bearing elements of the primary thermally insulating barrier.

[0098] This is a partial perspective view of the wall illustrating the secondary thermally insulating barrier, the secondary waterproofing membrane, the load-bearing elements of the primary thermally insulating barrier and the radiative multi-layer insulation blanket.

[0099] This is a partial perspective view, similar to that of the and in which internal trays intended to support the primary waterproofing membrane are also shown.

[0100] This is a sectional view of a wall of a sealed and thermally insulating tank according to a second embodiment.

[0101] This is a sectional view of a wall of a sealed and thermally insulating tank according to a third embodiment.

[0102] This is a partial, cross-sectional view of the wall of the, illustrating the insulating elements positioned between the radiative multi-layer insulation blanket and the secondary waterproofing membrane.

[0103] This is a partial sectional view of a wall of a sealed and thermally insulating tank according to another embodiment variant.

[0104] This is a schematic cutaway representation of a ship's tank and a loading / unloading terminal for this tank.

[0105] This is a partial sectional view of a wall of a sealed and thermally insulating tank according to another embodiment variant.

[0106] This is a partial sectional view of a wall of a sealed and thermally insulating tank according to another embodiment variant.

[0107] This is a partial sectional view of a wall of a sealed and thermally insulating tank according to another embodiment variant.

[0108] By convention, the terms "external" and "internal" are used to define the relative position of one element to another, with reference to the inside and outside of the tank.

[0109] The liquefied gas intended to be stored in the tank may in particular be liquid hydrogen, which has the particularity of being stored at approximately -253°C at atmospheric pressure.

[0110] Illustrates a supporting structure 1 against which a sealed and thermally insulating tank for storing liquefied gas is intended to be fixed.

[0111] The supporting structure 1 may in particular be formed of self-supporting metal sheets or, more generally, of any type of rigid partition having appropriate mechanical properties. The supporting structure 1 is, for example, formed by the double hull of a ship. In the, the supporting structure 1 has a generally polyhedral shape. It has two front and rear load-bearing walls 2, here of octagonal shape, of which only the rear load-bearing wall 2 is shown. The front and rear walls 2 are, for example, cofferdam walls of the ship which extend transversely to the longitudinal direction of the ship. The supporting structure 1 also comprises an upper load-bearing wall 3, a lower load-bearing wall 4 and side load-bearing walls 5, 6, 7, 8, 9, 10.

[0112] In relation to Figures 2 to 9 and 12, a wall 11 of a sealed and thermally insulating tank according to a first embodiment is described below. The wall 11 has a multilayer structure comprising, along the thickness direction of the wall 11, from the outside to the inside, a secondary thermally insulating barrier 12, a secondary sealing membrane 13, a primary thermally insulating barrier 14 and a primary sealing membrane 15 intended to be in contact with the liquefied gas contained in the tank.

[0113] The secondary thermally insulating barrier 12 is shown in the. It comprises a plurality of insulating panels 16 anchored to the supporting structure 1. The insulating panels 16 each comprise a layer of insulating polymer foam 17 sandwiched between an inner plate 18 and an outer plate 19. The inner 18 and outer 19 plates are, for example, plywood plates glued to said layer of insulating polymer foam 17. According to a variant, the inner 18 and outer 19 plates are made from a polymer matrix reinforced by fibers, such as glass fibers. The insulating polymer foam may in particular be a polyurethane-based foam. The polymer foam is, advantageously, reinforced by fibers, such as glass fibers, contributing to reducing its thermal contraction.

[0114] The insulating panels 16 are anchored to the supporting structure 1 by means of secondary anchoring devices, not shown. Each insulating panel 16 is, for example, fixed at at least each of its four corners. Each secondary anchoring device comprises a stud welded to the supporting structure 1 as well as a support member which is fixed on the stud and which bears against a support zone of the insulating panels 16. According to one embodiment, the external plate 19 of the insulating panels 16 projects beyond the layer of insulating polymer foam 17, at least at the corners of the insulating panel 16, so as to form the support zones of the insulating panels 16 cooperating with the support members of the secondary anchoring devices.Elastic members, such as Belleville washers, are advantageously threaded onto the stud, between a nut mounted on the stud and the support member, which makes it possible to ensure elastic anchoring of the insulating panels 16 on the supporting structure 1.

[0115] Advantageously, portions of mastic 20 are interposed between the external plate 19 of the insulating panels 16 and the supporting structure 1. The portions of mastic 20 thus contribute to compensating for the surface irregularities of the supporting structure 1. According to an advantageous alternative embodiment, the portions of mastic 20 adhere to the external plate 19 of the insulating panels 16 and to the supporting structure 1. The portions of mastic 20 thus participate in anchoring the insulating panels 16 on the supporting structure 1. In such an alternative embodiment, the secondary anchoring devices are optional.

[0116] The insulating panels 16 have substantially the shape of a rectangular parallelepiped and are juxtaposed in parallel rows and separated from each other by gaps 21 ensuring functional assembly clearance. The gaps 21 are filled with a heat-insulating filling, not shown, such as glass wool, rock wool or flexible open-cell polymer foam, for example. The gaps can also be filled with insulating plugs, as described in applications WO2019155157 or WO2021028624 for example.

[0117] In the embodiment shown, the internal face of the insulating panels 16 has two series of grooves 22 perpendicular to each other and intended to receive corrugations 24, projecting towards the outside of the tank, formed on the corrugated metal sheets 25 of the secondary waterproofing membrane 13. Each of the series of grooves 22 is parallel to two opposite sides of the insulating panels 16. In the embodiment shown, the grooves 22 pass entirely through the thickness of the internal plate 10 as well as an internal portion of the layer of insulating polymer foam 17. Advantageously, the grooves 22 have a shape complementary to those of the corrugations 24 of the secondary waterproofing membrane 13.

[0118] Furthermore, the inner plate 18 of the insulating panels 16 is equipped with metal plates 26 intended for anchoring the edges of the corrugated metal sheets 25 of the secondary waterproofing membrane 13 on the insulating panels 16. The metal plates 26 extend in two perpendicular directions which are each parallel to two opposite sides of the insulating panels 16. The metal plates 26 are fixed to the inner plate 18 of the insulating panels 16, by screws, rivets or staples, for example. The metal plates 26 are placed in recesses provided in the inner plate 18 so that the inner surface of the metal plates 26 is flush with the inner surface of the inner plate 18.

[0119] Furthermore, the insulating panels 16 have relaxation slots 27 which make it possible to reduce their stiffness so that the secondary thermally insulating barrier 12 deforms in the most homogeneous manner possible. This makes it possible to obtain the most uniform deformations possible of the corrugations 24 of the secondary waterproofing membrane 13. Advantageously, the insulating panels 16 have relaxation slots 27 at least opposite each of the corrugations 24 of the secondary waterproofing membrane 13. Thus, as illustrated for example in the, a relaxation slot 27 extends from the bottom of each of the grooves 22 towards the external plate 19 of the insulating panels 16. According to an optional variant, the insulating blocks 16 also comprise relaxation slots which open onto the external face of the insulating panels 16.Such relaxation slots are then not arranged opposite a corrugation 24 of the secondary sealing membrane 13 but halfway between two parallel corrugations 24.

[0120] Furthermore, as shown in the, the secondary waterproofing membrane 13 comprises a plurality of corrugated metal sheets 25 each having a substantially rectangular shape. The corrugated metal sheets 25 are, for example, made of Invar®: that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 -6 and 2.10 -6 K -1 , or in an iron alloy with a high manganese content whose coefficient of expansion is typically of the order of 7.10 -6 K -1 Alternatively, the corrugated metal sheets 25 can also be made of stainless steel or aluminum.

[0121] The corrugated metal sheets 25 are overlap-welded along their edges in order to ensure the sealing of the secondary waterproofing membrane 13. Furthermore, the corrugated metal sheets 25 are arranged in an offset manner relative to the insulating panels 16 of the secondary thermally insulating barrier 12 such that each of said corrugated metal sheets 25 extends jointly over several adjacent insulating panels 16. In order to ensure the anchoring of the secondary waterproofing membrane 13 on the secondary thermally insulating barrier 12, the edges of the corrugated metal sheets 25 are welded to the metal plates 26, for example by spot welding.

[0122] The secondary sealing membrane 13 has corrugations 24 and more particularly a first series of corrugations 24a extending parallel to a first direction and a second series of corrugations 24b extending parallel to a second direction. The directions of the series of corrugations 24a, 24b are perpendicular to each other. Each of the series of corrugations 24a, 24b is parallel to two opposite edges of the corrugated metal sheet 25. The corrugations 24 here project towards the outside of the tank, that is to say in the direction of the supporting structure 1. The secondary sealing membrane 13 comprises between the corrugations 24, a plurality of flat zones 28.

[0123] As shown in Figures 4 and 5, the corrugations 24 of the corrugated metal sheets 25 are housed in the grooves 22 formed in the internal face of the insulating panels 16 and in the gaps 21 formed between the adjacent insulating panels 16.

[0124] Furthermore, the flat areas 28 of the secondary waterproofing membrane 13 are each crossed by a primary anchoring device 29, illustrated in detail in the, and intended to ensure the anchoring of the load-bearing elements 30 of the primary thermally insulating barrier 14 on the insulating panels 16 of the secondary thermally insulating barrier 12. Each primary anchoring device 29 comprises a stud 31 which passes through the secondary waterproofing membrane 13. The stud 31 has an external end which is fixed to one of the insulating panels 16. To do this, in the embodiment shown, the external end of each stud 31 is threaded and is screwed into a threaded sleeve 32 which is fixed inside a bore formed in the internal plate 18 of one of the insulating panels 16. Furthermore, the stud 31 comprises a collar 33 developing radially relative to the axis of stud 31.

[0125] The collar 33 is welded in a sealed manner to the secondary sealing membrane 13 around the orifice of said secondary sealing membrane 13 crossed by the stud 31 in order to maintain the sealed nature of the secondary sealing membrane 13.

[0126] Furthermore, an external plate 34, also illustrated in the, has an orifice crossed by the stud 31. The primary anchoring device 29 comprises a nut 35 which is screwed onto an internal threaded end of the stud 31 and which thus makes it possible to hold the external plate 34 against the flat zone 28 opposite the secondary waterproofing membrane 13. The external plates 34 have a dual function. On the one hand, they make it possible to press the secondary waterproofing membrane 13 against the insulating panels 16 of the secondary thermally insulating barrier 12, in order to prevent it from being torn off due to excess pressure of the secondary thermally insulating barrier 12 relative to the primary thermally insulating barrier 14. On the other hand, they allow the fixing of the load-bearing elements 30 of the primary thermally insulating barrier 14 which will be described in detail below.

[0127] The external plates 34 are advantageously in contact against the corresponding flat zone 28 over more than 70% of the surface of said flat zone 28 and advantageously between 90 and 100% of its surface.

[0128] The external plates 34 are, for example, made of metal, such as stainless steel, but can also be made of a composite material, such as an epoxy resin loaded with glass fibers, for example.

[0129] As shown in the, the primary thermally insulating barrier 14 comprises a plurality of supporting elements 30 which extend in the thickness direction of the wall 11. The supporting elements 30 make it possible to support the primary sealing membrane 15 and, consequently, to take up the forces due to the hydrostatic and dynamic pressures exerted, on the primary sealing membrane 15, by the liquefied gas contained inside the tank. The supporting elements 30 are aligned in rows which are parallel to the direction of the corrugations of the first series of corrugations 24a and in rows parallel to the direction of the corrugations of the second series of corrugations 24b.

[0130] The supporting elements 30 each comprise an external base 36, an internal base 37 and a pillar 38 extending between the external base 36 and the internal base 37. The external base 36 and the internal base 37 each have a sleeve 39 in which one of the ends of the pillar 38 is received by fitting and a support collar 40 which extends radially from one end of the sleeve 39. In an alternative variant, it is the sleeves 39 of the external base 36 and of the internal base 37 which are received by fitting inside the pillars 38.

[0131] The external base 36 and the internal base 37 may be made of metal, such as stainless steel, or of a composite material, such as an epoxy resin filled with glass fibers, for example. The external base 36 and the internal base 37 may be fixed to the pillar 38 by any means and in particular by gluing.

[0132] According to another embodiment, the pillar 38 as well as the external base 36 and the internal base 37 are formed in one piece, by molding for example.

[0133] The pillars 38 have a tubular shape, preferably with a circular cross-section. According to an advantageous embodiment, the pillars 38 are made of a composite material comprising fibers and a matrix. Such pillars 38 make it possible to obtain satisfactory compressive strength for a limited conductive cross-section, which limits the conduction of heat from the outside to the inside of the tank through the pillars 38. The fibers are, for example, chosen from glass fibers, carbon fibers, aramid fibers, flax fibers, basalt fibers and mixtures thereof. The matrix is, for example, chosen from polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyoxymethylene, polyetherimide, polyacrylate, polyaryletherketone, polyetheretherketone, copolymers thereof, polyester, vinylester, epoxy and polyurethane.According to a particular embodiment, the pillars 38 are made of an epoxy resin reinforced with glass fibers.

[0134] The pillars 38 are advantageously provided with through-holes, not shown, which facilitate the depressurization of their internal space when the primary thermally insulating barrier 14 is depressurized, as described below. In addition, the internal space of the pillars 38 is advantageously lined with a gas-permeable insulating lining and more particularly made of a porous open-cell material. The insulating lining is, for example, an open-cell insulating polymer foam, such as open-cell polyurethane foam, glass wool, rock wool, melamine foam, polyester wadding, polymer aerogels, such as polyurethane-based aerogel, notably sold under the brand name Slentite ®, or silica aerogels.

[0135] Alternatively or additionally, the internal space may also include a multi-layer radiative insulation cover made from a material designated by the acronym MLI for "multi-layer insulation" in English, which will be described later, aimed at reducing heat loss by thermal radiation.

[0136] The support collars 40 of the external bases 36 are each fixed to one of the external plates 34. As illustrated in the, each support collar 40 of the external bases 36 is, for example, fixed to the external plate 34 by means of rivets 41 distributed around the axis of the carrier element 30.

[0137] Furthermore, as illustrated in the, the support collars 40 of the internal bases 37 are each supported and fixed against an internal plate 42. The internal plates 42 are, for example, made of a metal, such as stainless steel. The support collars 40 of the internal bases 37 are, for example, fixed to the internal plate 42 by means of rivets 43 distributed around the axis of the carrier element 30.

[0138] The load-bearing elements 30 thus form discrete support structures which are not rigidly connected to each other and which each support a flat area 46 of the primary waterproofing membrane 15, which allows good distribution of the stresses between the corrugations 45 of the primary waterproofing membrane 15.

[0139] Returning to the, we observe the primary waterproofing membrane 15 which is also obtained by assembling a plurality of corrugated metal sheets 44. The corrugated metal sheets 44 each have a substantially rectangular shape. The corrugated metal sheets 44 are, for example, made of Invar®: that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 -6 and 2.10 -6 K -1 , or in an iron alloy with a high manganese content whose coefficient of expansion is typically of the order of 7.10 -6 K -1 Alternatively, the corrugated metal sheets 44 can also be made of stainless steel or aluminum.

[0140] The corrugated metal sheets 44 are overlap welded along their edges in order to ensure the sealing of the primary waterproofing membrane 15. The primary waterproofing membrane 15 comprises corrugations 45. More particularly, it comprises a first series of corrugations 45a extending parallel to a first direction and a second series of corrugations 45b extending parallel to a second direction. The directions of the series of corrugations 45a, 45b are perpendicular and are parallel or perpendicular to the rows of load-bearing elements 30. Each of the series of corrugations 45a, 45b is parallel to two opposite edges of the corrugated metal sheets 44. The corrugations 45 project towards the inside of the tank, i.e. in the opposite direction to the load-bearing structure 1. Each corrugated metal sheet 44 comprises between the corrugations 45, a plurality of flat zones 46.

[0141] The pitch of the corrugations 24 of the secondary waterproofing membrane 13 is equal to the pitch of the corrugations 45 of the primary waterproofing membrane 15 or to an integer multiple thereof. In addition, each of the corrugations 24 of the secondary waterproofing membrane 13 is arranged opposite, in the thickness direction of the wall 11, a corrugation 45 of the primary waterproofing membrane 15. Thus, each flat zone 46 of the primary waterproofing membrane 15 is located opposite, in the thickness direction of the wall 11, a flat zone 28 of the secondary waterproofing membrane 13. Therefore, the axis of each supporting element 30 passes both through the center of a flat zone 46 of the primary waterproofing membrane 15 and through the center of a flat zone 28 of the secondary waterproofing membrane 13.

[0142] Advantageously, the internal plates 42 are each in contact against the corresponding flat zone 46 of the primary sealing membrane 15 over more than 70% of the surface of said flat zone 46 and advantageously between 90 and 100% of its surface.

[0143] The corrugated metal sheets 44 of the primary waterproofing membrane 15 are at least anchored, by welding, along their edges to the internal plates 42. To do this, the edges of the corrugated metal sheets 44 are welded to the internal plates 42, for example by spot welds. According to an advantageous embodiment, the corrugated metal sheets 44 are also anchored to internal plates 42 outside their edge areas. To do this, the corrugated metal sheets 44 can in particular be welded to the internal plates 42 by transparent welds. According to an advantageous embodiment, the corrugated metal sheets 44 are welded to each of the internal plates 42 which support them. Such an embodiment is particularly advantageous in that it makes it possible to distribute the stresses even more uniformly between the corrugations 45 of the primary waterproofing membrane 15.

[0144] Furthermore, the primary thermally insulating barrier 14 has a gas phase which is under vacuum, that is to say has an absolute pressure lower than atmospheric pressure, in order to give the primary thermally insulating barrier 14 the required thermally insulating properties. The gas phase of the primary thermally insulating barrier 14 is, advantageously, placed at an absolute pressure lower than 1 Pa, advantageously lower than 10 -1 Pa, preferably less than 10 –2 Pa and for example of the order of 10 -3Pa. To do this, the primary thermally insulating barrier 14 is advantageously connected to a vacuum pump. According to an advantageous embodiment, a cryopumping phenomenon is used, as an alternative or complement to the aforementioned vacuum pump, to obtain the target vacuum level in the primary thermally insulating barrier 14. Also, prior to its being put under vacuum, the primary thermally insulating barrier 14 is charged with an inert gas having a solid condensation temperature higher than the liquefaction temperature of the liquefied gas stored in the tank. For example, when the liquefied gas stored in the tank is liquid hydrogen, the inert gas may be carbon dioxide.Thus, taking into account the temperature of the hydrogen in the liquid state, the carbon dioxide contained in the primary thermally insulating barrier 14 condenses in the solid state in the primary thermally insulating barrier 14, which contributes to reducing the pressure in the latter.

[0145] In addition to being depressurized, the primary thermally insulating barrier 14 comprises insulating materials to further increase its insulation properties. Also, as shown in the, the primary thermally insulating barrier 14 comprises a radiative multilayer insulation blanket 47 which reduces heat transfer by thermal radiation. The radiative multilayer insulation blanket 47 is typically made of a material designated by the acronym MLI for "multi-layer insulation" in English. Thus, the radiative multilayer insulation blanket 47 has a stack of a plurality of sheets made either of metal, such as aluminum or silver for example, or of a metal-coated polymer material, said sheets being separated from each other by a woven or non-woven textile layer made with polymer fibers, such as polyester fibers, or glass fibers.Polymer material sheets are, for example, made of Polyimide, notably marketed under the brand Kapton ®, or of polyethylene terephthalate, notably marketed under the brand Mylar ®. These thin sheets are coated, on each side, with a metal, such as aluminum or silver.

[0146] As illustrated in the, the radiative multi-layer insulation blanket 47 has openings through which the pillars 38 of the load-bearing elements 30 pass. Advantageously, the radiative multi-layer insulation blanket 47 is positioned in the coldest part of the primary thermally insulating barrier 14. In other words, the radiative multi-layer insulation blanket 47 is positioned in a plane which is parallel to the secondary 13 and primary 15 waterproofing membranes but is closer to the primary waterproofing membrane 15 than to the secondary waterproofing membrane 13. This increases the effectiveness of the radiative multi-layer insulation blanket 47 since it is thus positioned in the coldest area of ​​the primary thermally insulating barrier 14 so that the emissivity of each of its layers is reduced.

[0147] The radiative multilayer insulation blanket 47 is here fixed to the pillars 38 of the supporting elements 30, for example by gluing or by means of pairs of velvet-hook type fixing strips, one of the strips of which is associated with the radiative multilayer insulation blanket 47, for example by sewing or gluing, and the other strip of which is glued to one of the pillars 38.

[0148] As shown in the, the primary thermally insulating barrier 14 further comprises insulating elements 51 which have an open-cell porous structure. The insulating elements 51 are disposed between the radiative multi-layer insulation blanket 47 and the secondary sealing membrane 13.

[0149] Such insulating elements 51 have several functionalities. Firstly, they make it possible to further reduce the temperature of the area of ​​the primary thermally insulating barrier 14 in which the radiative multilayer insulation blanket 47 is positioned, which further increases its effectiveness. Secondly, the insulating elements 51 also make it possible to limit the degradation of the thermal insulation performance when the pressure inside the primary thermally insulating barrier 14 is higher than the pressure values ​​prescribed for the use of the radiative multilayer insulation blanket 47 alone. Indeed, the radiative multilayer insulation blankets 47 of the aforementioned type have excellent thermal insulation performance for low pressure values, typically less than or equal to 10 -3Pa but the more they are subjected to pressures above the aforementioned threshold, the more their performance deteriorates. Such pressure conditions are particularly likely to occur in the event of loss of tightness of the primary sealing membrane 15 or of the secondary sealing membrane 13 degrading the vacuum level inside the primary thermally insulating barrier 14, or when the tank is cooled down as long as the inert gas contained in the primary thermally insulating barrier 14 has not entirely condensed to the solid state or when the filling rate of the tank is low, for example during a return voyage of a ship when the tank only has a heel of liquefied gas. The insulating elements 51 also make it possible to reduce the activation capacities of convective flows inside the primary thermally insulating barrier 14.Thirdly, the insulating elements 51 constitute surfaces for receiving the solids resulting from the solid condensation of the inert gas(es) contained in the primary thermally insulating barrier 14, which makes it possible to limit the mechanical stresses likely to be exerted on the other elements of the wall 11 and in particular on the load-bearing elements 30, the radiative multi-layer insulation cover 47 and the secondary 13 and primary 15 sealing membranes.

[0150] The insulating elements 51 are, for example, chosen from glass wool, rock wool, polyester wadding, open-cell polymer foams, such as open-cell polyurethane foam, and melamine foams. Advantageously, the insulating elements 51 are made of glass wool. The insulating elements 51 are advantageously packaged in the form of panels having a structural strength allowing them to be handled easily.

[0151] In the embodiment shown in the, the insulating elements 51 occupy all the space between the radiative multilayer insulation cover 47 and the secondary sealing membrane 13. The secondary thermally insulating barrier further comprises one or more retention members making it possible to limit the movement of the insulating elements 51 in the direction of the primary sealing membrane 15 and thus prevent them from compressing the radiative multilayer insulation cover 47 and thus degrading its performance.

[0152] The retention member is here a textile retention layer 52, for example made with polymer fibers, such as polyester fibers, or glass fibers. The textile retention layer 52 is fixed to the carrier elements 30. This textile retention layer 52 can be fixed to the carrier elements by any means and in particular by gluing. On the, the textile retention layer 52 is fixed to the carrier elements 30 by means of collars 53 which are, on the one hand, fixed to the carrier elements 30 and, on the other hand, fixed to the textile retention layer 52.

[0153] In such an embodiment, the radiative multilayer insulation blanket 47 can be fixed to the textile retention layer 52, by means of regularly distributed bonding zones, seams or staples. This thus makes it possible to prevent the radiative multilayer insulation blanket 47 from being directly fixed to the load-bearing elements 30 and thus makes it possible to reduce thermal bridges by conduction. This also makes it possible to ensure good positioning of the radiative multilayer insulation blanket 47, by limiting its folds and ensuring its maintenance, in particular when the pressure level in the primary thermally insulating barrier 14 is not homogeneous and there is excess pressure between the radiative multilayer insulation blanket 47 and the secondary sealing membrane 13.

[0154] According to an alternative embodiment shown in the, the retention members are formed by collars 54 fixed to the supporting elements 30 and against which the internal face of the insulating elements 51 abut.

[0155] It is also observed, in the variant embodiment of the, that the insulating elements 51 have a thickness less than the distance, in the direction of thickness of the wall 11, between the secondary sealing membrane 13 and the radiative multilayer insulation cover 47. In other words, an empty space is present between the insulating elements 51 and the radiative multilayer insulation cover 47. This makes it possible to reduce the quantity of insulating elements 51 used and thus contributes to reducing the costs of the tank without significantly degrading the thermal insulation performance of the primary thermally insulating barrier 14, in particular when the pressure inside the primary thermally insulating barrier 14 is higher than the prescribed pressure values.

[0156] Illustrates a wall of a sealed and thermally insulating tank according to a second embodiment, the insulating elements 51 not being shown. This embodiment differs from that described above in relation to Figures 2 to 9 and 12 in that the corrugations 24 of the secondary sealing membrane 13 do not project outwards, that is to say towards the supporting structure 1, but inwards, that is to say in a direction opposite to the supporting structure 1.

[0157] Illustrates a wall of a sealed and thermally insulating tank according to a third embodiment, the insulating elements 51 not being shown. This embodiment differs from that described above in relation to Figures 2 to 9 and 12 in that the primary sealing membrane 15 has two layers 48, 49 of corrugated metal sheets 44 superimposed on each other. This ensures redundancy of the sealing function and thus improves the reliability of the primary sealing membrane 15.

[0158] The two layers 48, 49 of corrugated metal sheets 44 each have a structure similar to that of the primary waterproofing membrane 15 described above in relation to the. The corrugations 45 of the two layers 48, 49 are arranged at identical pitches and are arranged opposite each other in the thickness direction of the wall 11.

[0159] Furthermore, spacer elements, not shown, having a predetermined thickness are interposed between the two layers 48, 49 so that the distance between them is kept substantially constant. Such spacer elements are, for example, positioned in the flat areas 46 of the corrugated metal sheets 44. The spacer elements are, for example, each fixed to an internal plate 42, by an anchoring device, not shown, passing through the layer 48. In addition, the edges of the corrugated metal sheets 44 of the layer 49 are anchored, for example by welding, on anchoring plates, also not shown, fixed to the spacer elements or formed by them. According to one embodiment, the spacer elements are made of thermally conductive materials, such as metal and in particular stainless steel.This makes it possible to limit the temperature difference between the two layers 48, 49 of the primary sealing membrane 15 and consequently to limit the effects of this double layer on the kinetics of the cryopumping phenomenon inside the primary thermally insulating barrier 14.

[0160] According to one embodiment, the gas phase of the additional space 50 which is interposed between the two layers 48, 49 of the primary sealing membrane 15 is placed under vacuum, that is to say at a pressure lower than atmospheric pressure. The gas phase of the additional space 50 is advantageously placed at an absolute pressure lower than 10 -1 Pa, preferably less than 10 –2 Pa, for example of the order of 10 –3 Pa. To do this, the additional space 50 is connected to a vacuum pump.

[0161] According to another embodiment variant, the additional space 50 is swept by an inert gas. The inert gas is, for example, helium which has a liquefaction temperature lower than that of hydrogen, which makes it possible to prevent the inert gas from condensing in the additional space 50. To do this, the installation comprises an inert gas tank associated with an inerting circuit which is connected to the additional space 50 and to a gas analyzer which is configured to detect a presence of the gas stored in the tank, for example hydrogen, among the inert gas circulating in the additional space 50. Such an inert gas sweep thus makes it possible to detect leaks from the layer 49 of the primary sealing membrane 15.

[0162] According to another embodiment not shown, the sealed and thermally insulating tank is not a membrane tank but a tank in which the liquefied gas is stored under pressure. Such tanks are self-supporting. Thus, in the case of a tank embarked on a ship, the tank does not use the double hull of the ship as a supporting structure like the membrane tank described above. In such a naval context, these tanks are designated type C tanks. In a land context, these tanks are designated by the expression "pressure tank", as defined in the CODAP code. The tank comprises two self-supporting sealed barriers, for example cylindrical, which are positioned one inside the other. The two sealed barriers are fixed and maintained at a distance from each other by spacer structures.The thermally insulating barrier formed between the two barriers has characteristics similar to those of the primary thermally insulating barrier 14 described above. In particular, the thermally insulating barrier is placed in depression, comprises a radiative multilayer insulation blanket 47 and insulating elements 51 which are positioned between the radiative multilayer insulation blanket 47 and the external sealed barrier. The relative arrangement of the radiative multilayer insulation blanket 47 and the insulating elements 51 is identical to that described above in relation to FIGS. 12 and 13, that is to say that from the outside to the inside of the tank, the wall comprises an external sealed barrier, the insulating elements 51, the radiative multilayer insulation blanket 47 and the external sealed barrier which is intended to be in contact with the liquefied gas stored in the tank.

[0163] In a tank of the aforementioned type, the radiative multilayer insulation cover 47 may in particular be fixed to the internal watertight barrier, for example by gluing. Alternatively, the radiative multilayer insulation cover 47 may also be fixed to the insulating elements 51, by any suitable means and in particular by gluing, sewing, stapling or other. The insulating elements 51 are anchored to the external watertight barrier, by any suitable means and in particular by gluing or by means of mechanical anchoring devices.

[0164] Furthermore, according to an alternative embodiment in which the radiative multilayer insulation cover 47 is not fixed to the insulating elements 51 so that a free space is present in the direction of thickness of the wall between the radiative multilayer insulation cover 47 and the insulating elements 51, an additional layer can be fixed to the internal face of the insulating elements 51. This additional layer can be made of a woven or non-woven textile, a metal film or a film of polymer material coated with a metal. The aforementioned additional layer can thus contribute to one and / or the other of the following two functions: increasing the pressure drop of the gas flow so as to reduce convection movements, in particular in degraded vacuum conditions and reducing the emissivity of the internal face of the insulating elements 51.

[0165] La illustrates yet another alternative embodiment. This embodiment differs from that described above in relation to la in that it comprises several radiative multilayer insulation blankets 47, 55. In the illustrated alternative embodiment, the primary thermally insulating barrier 14 comprises two radiative multilayer insulation blankets 47, 55 which are spaced apart from each other in the thickness direction of the wall. According to an exemplary embodiment, the two radiative multilayer insulation blankets 47, 55 are spaced apart in the thickness direction of the wall by a distance of between 30 and 160 mm. The presence of several radiative multilayer insulation blankets 47, 55 makes it possible to further reduce heat transfer by thermal radiation.

[0166] In this embodiment, each radiative multilayer insulation blanket 47, 55 consists of several portions which are fixed to each other by fixing means 56, such as hook-and-loop type fixing strips. Furthermore, advantageously, in order to limit thermal bridges, the fixing strips of the two radiative multilayer insulation blankets 47, 55 are offset from each other, that is to say they are not positioned between the same two rows of load-bearing elements 30.

[0167] La illustrates yet another embodiment. As in embodiment 1a, the primary thermally insulating barrier 14 comprises two radiative multilayer insulation blankets 47, 55 which are spaced from each other in the thickness direction of the wall. However, the primary thermally insulating barrier 14 further comprises insulating elements 57 which have an open-cell porous structure and which are disposed between the outermost radiative multilayer insulation blanket 55 and the secondary sealing membrane 13. Such insulating elements 57 have identical functionalities to the insulating elements 51 described above in relation to FIGS. 12 and 13.

[0168] The insulating elements 57 are, for example, chosen from glass wool, rock wool, polyester wadding, open-cell polymer foams, such as open-cell polyurethane foam, and melamine foams. Advantageously, the insulating elements 57 are made of glass wool. The insulating elements 57 are advantageously packaged in the form of panels having a structural strength allowing them to be handled easily.

[0169] La illustrates yet another embodiment. This embodiment differs from the embodiment described above in relation to la in that each of the pillars 38 of the load-bearing elements 30 is at least partially coated with a radiative insulation coating 58 which surrounds said pillar 38. Such a radiative insulation coating 58 limits the absorption by the pillars of the radiation reflected by the radiative multilayer insulation cover 47.

[0170] The radiative insulation coating 58 extends at least from the inner end of the pillar 38 to the radiative multilayer insulation cover 47. Advantageously, the radiative insulation coating 58 extends to the outer end of the pillar 38. The radiative insulation coating 58 may be glued to the pillar or adhered directly to it. Alternatively, it may also be fixed between the inner base 37 and the outer base 36. In embodiments not shown, the radiative insulation coating 58 rests on and / or is fixed to a textile retention layer 52, as shown in the figure or to collars 54, as shown in the figure.The radiative insulation coating 58 is chosen from the materials designated by the acronym SLI for “Single Layer Insulation” in English which comprises, for example, a sheet of polymer material, such as Polyimide, or polyethylene, coated with a metal, such as aluminum, the materials designated by the acronym MLI and described previously and a layer previously deposited on the pillar 37 and comprising a binder and aluminum particles.

[0171] With reference to the, a cutaway view of a ship 70 shows a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the liquefied gas, preferably liquid hydrogen, contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, 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.

[0172] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer a cargo of liquefied gas from or to the tank 71.

[0173] It also represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The orientable mobile arm 74 adapts to all sizes of hydrogen carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the hydrogen carrier 70 to be loaded and unloaded from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 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 makes it possible to keep the hydrogen carrier vessel 70 at a great distance from the coast during loading and unloading operations.

[0174] To generate the pressure necessary for the transfer of the liquefied gas, it is possible either to use pumps on board the ship 70 and / or pumps fitted to the onshore installation 77 and / or pumps fitted to the loading and unloading station 75 or to allow a rise in pressure in the interior space of the tank under the effect of the evaporation of the liquefied gas stored in the tank.

[0175] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto 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.

[0176] The use of the verb "comprise", "comprise" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

[0177] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

[0178] It will more generally appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them. In the following claims, the terms used should not be interpreted as limiting the claims to the embodiments set out in the present description, but should be interpreted to include all equivalents which the claims are intended to cover by virtue of their wording and the prediction of which is within the reach of those skilled in the art based on their general knowledge.

Claims

Wall for a sealed and thermally insulated tank for storing a liquefied gas, said wall (11) comprising successively, along a thickness direction, from the outside to the inside of the tank, an external sealed barrier (13), a thermally insulating barrier (14) and an internal sealed barrier (15), the thermally insulating barrier (14) having a gaseous phase at an absolute pressure of less than 1 Pa and comprising: - a radiative multilayer insulation blanket (47) which extends orthogonally to the thickness direction, said radiative multilayer insulation blanket (47) comprising a stack of a plurality of sheets of metal or of polymer material coated with a metal and separated from each other by a textile layer; and - insulating elements (51) having a porous open-cell structure which are arranged between the radiative multilayer insulation blanket (47) and the external sealed barrier (13). Wall (11) according to claim 1, wherein the internal leak-proof barrier (15) is intended to be in contact with the liquefied gas contained in the tank. Wall (11) according to claim 1 or 2, wherein the insulating elements (51) are selected from glass wool, rock wool, polyester wadding and open-cell polymer foams. Wall (11) according to any one of claims 1 to 3, wherein the radiative multilayer insulation blanket (47) is positioned in a plane that is closer to the internal airtight barrier (15) than to the external airtight barrier (13). Wall (11) according to any one of claims 1 to 4, wherein the textile layer of the radiative multilayer insulation blanket (47) is made with fibers selected from polymer fibers and glass fibers. Wall (11) according to any one of claims 1 to 5, wherein the metal or metal-coated polymer material sheets are made of a material selected from aluminium, silver, aluminium-coated polymer materials and silver-coated polymer materials. Wall (11) according to any one of claims 1 to 6, wherein the gaseous phase of the thermally insulating barrier (14) comprises, when the thermally insulating barrier is conditioned at ambient temperature, more than 50% by volume of an inert gas having a solid condensation temperature higher than the liquefaction temperature of the liquefied gas intended to be stored in the tank. Wall (11) according to claim 7, wherein the inert gas is carbon dioxide. Wall (11) according to any one of claims 1 to 8, wherein the thermally insulating barrier (14) comprises load-bearing elements (30) which rise in the thickness direction between the external airtight barrier (13) and the internal airtight barrier (15), the radiative multilayer insulation blanket (47) having openings through which the load-bearing elements pass. Wall (11) according to claim 9, wherein the load-bearing elements (30) each comprise an external base (36), an internal base (37) and a pillar (38), each of the external (36) and internal (37) bases having a sleeve (39) cooperating by interlocking with one of the ends of the pillar (38) and a support collar (40) extending radially from one end of the sleeve (39). Wall (11) according to claim 10, wherein the pillar (38) is at least partially coated with a radiative insulation coating (58) which surrounds said pillar (38). Wall (11) according to any one of claims 9 to 11, wherein the thermally insulating barrier (14) further comprises at least one retention device (52, 54) which is fixed to the load-bearing elements (30) so as to limit the movement of the insulating elements (51) towards the internal airtight barrier (15). Wall (11) according to claim 12, wherein at least one retention element comprises a textile retention layer (52) which is fixed to the load-bearing elements (30) and which is disposed between the insulating elements (51) and the multilayer radiative insulation cover (47). Wall (11) according to claim 13, wherein the radiative multilayer insulation blanket (47) is fixed on the textile retention layer (52). Wall (11) according to claim 13 or 14, wherein the textile retention layer (52) is made with fibers selected from polymer fibers and glass fibers. Wall (11) according to any one of claims 12 to 15, wherein the thermally insulating barrier (14) comprises several retention members, each of which is formed by a collar (54) fixed to one of the load-bearing elements (30) and against which an internal face of one of the insulating elements (51) abuts. Wall (11) according to any one of claims 1 to 16, wherein the thermally insulating barrier (14) comprises several radiative multilayer insulation blankets (47, 55) each extending orthogonally to the thickness direction, each said radiative multilayer insulation blanket (47, 55) comprising a stack of a plurality of sheets of metal or metal-coated polymer material separated from each other by a textile layer. Wall (11) according to claim 17, in which the thermally insulating barrier (14) comprises two radiative multilayer insulation blankets (47, 55) which are preferably spaced at a distance of between 30 and 160 mm. Wall (11) according to any one of claims 1 to 18, wherein the internal sealing barrier is a primary sealing membrane (15) intended to be in contact with the liquefied gas contained in the tank, the thermally insulating barrier is a primary thermally insulating barrier (14) and the external sealing barrier is a secondary sealing membrane (13), the wall (11) further comprising a secondary thermally insulating barrier (12) resting against a load-bearing structure (1) and against which rests the secondary sealing membrane (13). Wall (11) according to claim 19, wherein the primary sealing membrane (15) comprises a first series of corrugations (45a) having first corrugations parallel to each other and a second series of corrugations (45b) having second corrugations parallel to each other and perpendicular to the first corrugations, the primary sealing membrane (15) comprising a plurality of flat zones (46) which are each defined between two adjacent first corrugations and between two adjacent second corrugations;the primary thermally insulating barrier (14) comprising at least a first row of load-bearing elements comprising successively, in a direction parallel to the first undulations, at least a first, a second and a third load-bearing elements (30) which are fixed to the secondary thermally insulating barrier (12) and which rise in the thickness direction, the first, second and third load-bearing elements (30) being respectively fixed to a first, a second and a third internal plates (42), the plurality of flat zones (46) comprising successively, in the direction parallel to the first undulations, a first, a second and a third flat zones which are respectively welded in support against the first, the second and the third internal plates (42). Wall (11) according to any one of claims 1 to 20, wherein the external watertight barrier and the internal watertight barrier are self-supporting barriers connected to each other by strut structures. A sealed and thermally insulating tank comprising a plurality of walls (11) according to any one of claims 1 to 21. Vessel (70) for the transport of a liquefied gas, the vessel comprising a double hull (72) and a tank (71) according to claim 22 disposed in the double hull. Transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 23 and insulated pipelines (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the vessel to a floating or land-based storage facility (77). Method of loading or unloading a ship (70) according to claim 23, in which 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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