Liquefied gas storage facility

Abstract

The invention relates to a liquefied gas storage facility comprising a through-structure (9) positioned in a passage extending through a load-bearing roof wall and a tank wall, the through-structure comprising: a main envelope (10) sealingly delimiting an internal space (11) at an absolute pressure of less than 10 Pa, said main envelope comprising - a central portion, - an inner portion, - an outer portion; an outer peripheral fastening element connecting the outer portion to the load-bearing roof wall, a closure wall (20) extending around and at a distance from the central portion, the closure wall sealingly connecting the outer peripheral fastening element to the sealed membrane (5), an inner peripheral fastening element, the sealed membrane (7) being sealingly fastened to the inner peripheral fastening element, and a sealed pipe (16).

Description

Liquefied gas storage facility

[0001] The invention relates to the field of liquefied gas storage facilities. In particular, the invention relates to the field of liquefied gas storage facilities comprising a sealed and thermally insulating tank 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, installations are known comprising a sealed and thermally insulating tank for storing liquefied gas such as liquefied natural gas (LNG). Such a tank comprises a multi-layer structure comprising successively, in a thickness direction from the outside of the tank, a secondary thermally insulating barrier, a secondary sealed membrane, a primary thermally insulating barrier and a primary sealed membrane delimiting an internal space of the tank intended to contain a liquefied gas.

[0003] Such an installation comprises a load-bearing ceiling wall. It is known in the state of the art to arrange a through passage in a ceiling wall in order to insert a piping system, which may be called the "liquid dome", opening into the internal space of the tank.

[0004] The inventors noted that the very low temperature of liquid hydrogen and the presence of thermal bridges at the level of such a passage could cause cold spots at the level of the load-bearing wall which could lead to the liquefaction of the air and the alteration of the load-bearing wall, for example constituting part of the hull of the ship.

[0005] Furthermore, the inventors found that the presence of thermal bridges could also cause cold spots at the secondary membrane, causing the liquefaction of the gas present at the secondary thermally insulating barrier. Such liquefaction could cause damage to the secondary barrier and the load-bearing wall.

[0006] Therefore, it is important to avoid cold spots on the hull, in particular to prevent the liquefaction of air and damage to the ship's hull.

[0007] It is therefore also important to avoid cold spots at the secondary membrane to prevent condensation of the gas present at the secondary thermally insulating barrier.

[0008] One idea behind the invention is to solve one or more of the above-mentioned problems.

[0009] An idea underlying the invention is to propose a liquefied gas storage installation comprising a through structure opening into the internal space in order to allow the passage of a fluid, such as liquefied gas, for example liquefied hydrogen or LH2, from the outside of the tank to the inside of the tank or vice versa.

[0010] One idea behind the invention is to propose a liquefied gas storage installation comprising a through structure opening into the internal space of the tank, optimized to limit thermal bridges at the level of the through structure.

[0011] According to one embodiment, the invention provides a liquefied gas storage facility comprising a supporting structure and a sealed and thermally insulating tank installed in the supporting structure, the supporting structure comprising a ceiling load-bearing wall, the sealed and thermally insulating tank comprising a tank wall fixed to the ceiling load-bearing wall, the tank wall successively comprising, in a thickness direction from the outside of the tank, a secondary thermally insulating barrier, a secondary sealed membrane, a primary thermally insulating barrier and a primary sealed membrane delimiting an internal space of the tank intended to contain a liquefied gas, said liquefied gas storage facility comprising a through-structure carried by the ceiling load-bearing wall and positioned in a passage provided through the ceiling load-bearing wall and the tank wall,the through structure comprising:a main envelope sealingly delimiting an interior space, said main envelope comprising:- a central portion extending in the thickness direction between the ceiling load-bearing wall and the primary waterproof membrane,- an internal portion in contact with the internal space,- an external portion projecting towards the outside of the tank from the ceiling load-bearing wall,said interior space containing a gaseous phase at an absolute pressure of less than 10 Pa,an external peripheral fixing element connecting the external portion of the main envelope to the ceiling load-bearing wall all around said passage,a secondary closure wall extending around the central portion of the main envelope at a distance from the central portion,the secondary closure wall sealingly connecting the external peripheral fixing element to the secondary waterproof membrane to close the secondary thermally insulating barrier all around said passage and to form an intermediate space between the secondary closure wall and the central portion of the main envelope, the intermediate space being in communication with the primary thermally insulating barrier, an internal peripheral fixing element which projects outwards from the internal portion, the primary waterproof membrane being sealed to the internal peripheral fixing element all around the main envelope, and a sealed pipe successively passing through the external portion, the internal space and the internal portion of the main envelope and opening into the internal space, an internal portion of the sealed pipe being fixed to the internal portion of the main envelope.,

[0012] Thanks to these characteristics, it is possible to obtain a gas storage installation allowing the passage of a liquid such as liquid hydrogen and / or a gas such as hydrogen between the outside and the inside of the tank while significantly reducing thermal bridges at the passage level. Such an installation makes it possible to preserve the secondary waterproof membrane and the load-bearing ceiling wall from cold spots.

[0013] Indeed, the presence of the intermediate space tends to increase the length of a thermal conduction path from the internal space of the tank to the ceiling load-bearing wall compared to the known through structures used in particular for tanks intended to contain LNG. In addition, the use of a sealed envelope limits convective flows around the sealed pipe. As a result, the ceiling load-bearing wall and the secondary waterproof membrane can be preserved.

[0014] According to embodiments, such a liquefied gas storage facility may comprise one or more of the following features.

[0015] According to an alternative embodiment of the internal peripheral fixing element, the internal peripheral fixing element projects outwardly from the central portion.

[0016] According to one embodiment, the gas phase contained in the interior space of the through-structure is at an absolute pressure less than 1 Pa, preferably less than 10 -3 Pa.

[0017] According to one embodiment, the interior space of the main envelope comprises a thermal insulator chosen from: glass wool, perlite or a material designated by the acronym MLI for “multi-layer insulation” in order to increase the thermal insulation of the interior space of the main envelope.

[0018] According to one embodiment, the external peripheral fixing element comprises an external collar fixed to the load-bearing ceiling wall all around said passage.

[0019] According to one embodiment, the collar is metallic and fixed to the load-bearing ceiling wall by welding.

[0020] According to one embodiment, the external peripheral fixing element comprises an external peripheral envelope connecting the external portion of the main envelope to the external collar.

[0021] According to one embodiment, the outer peripheral envelope extends from the outer portion of the main envelope, around the outer portion of the main envelope and is arranged to close the intermediate space.

[0022] According to one embodiment, the outer peripheral casing comprises a first wall projecting outwardly from the outer portion of the main casing, all around the main casing and a second wall connecting the first wall to the outer collar, all around the outer collar.

[0023] According to one embodiment, the second wall of the external peripheral envelope is located opposite the secondary closing wall relative to the external collar.

[0024] According to one embodiment, the outer collar extends parallel to the ceiling load-bearing wall inside the passage and has a first portion forming part of the main casing and a second portion projecting outside the main casing to connect the main casing to the ceiling load-bearing wall all around said passage, the outer portion of the main casing comprising: - a first wall projecting towards the outside of the tank from the first portion of the outer collar, - a second wall located at a distance from the first wall towards the inside of the passage and arranged to close the intermediate space, the second wall having a broken line shape comprising an outgoing portion projecting towards the outside of the tank from the first portion of the outer collar and a re-entrant portion extending from the outgoing portion towards the inside of the tank in the thickness direction.

[0025] According to one embodiment, the main casing has a shape of revolution, and in which the central portion comprises a side wall having an inner end and an outer end, the inner portion comprises a bottom wall closing the inner end of the side wall and being crossed by the sealed pipe, and the outer portion comprises a cover wall closing the outer end of the side wall and being crossed by the sealed pipe.

[0026] According to one embodiment, the main envelope has a diameter of between 800 mm and 1500 mm, preferably a diameter of between 1000 mm and 1200 mm.

[0027] According to one embodiment, the sectional view perpendicular to the thickness direction of the main envelope has a circular or rectangular shape.

[0028] According to one embodiment, the distance between the inner end and the outer end of the main envelope is at least 80 cm, preferably 100 cm.

[0029] According to one embodiment, an external portion of the sealed pipe is connected in a sealed manner to an external surface of the external portion of the main casing by a compensation bellows, the compensation bellows being intended to take up variations in length resulting from thermal contraction.

[0030] Thus, the bellows allows in particular to take up the vertical thermal contraction on the one hand and the radial thermal contraction in the lower part on the other hand.

[0031] According to one embodiment, the sealed pipeline comprises a double peripheral wall enclosing a peripheral vacuum space, the peripheral vacuum space is preferably at a pressure lower than 10 Pa and even more preferably at a pressure lower than 1 Pa.

[0032] Thus, the vacuum space allows to increase the thermal insulation of the sealed pipeline.

[0033] According to one embodiment, the double peripheral wall of the sealed pipeline extends from the interior space of the main casing to the exterior of the external portion of the main casing.

[0034] According to one embodiment, the sealed pipeline comprises a double peripheral wall, the peripheral space of which is in communication with the interior space of the main casing. In this embodiment, the pressure in the peripheral space is identical to the pressure in the interior space of the main casing.

[0035] According to one embodiment, a thermal insulator is positioned against an exterior surface of the sealed pipeline.

[0036] According to one embodiment, the thermal insulation covers the outer surface of the sealed pipe which is located in the interior space of the main envelope, preferably covering the entirety of said outer surface.

[0037] According to one embodiment, the through structure comprises an internal anchoring cylinder projecting from the internal portion of the main casing towards the internal space of the tank, the sealed pipe being fixed in a sealed manner to said internal anchoring cylinder.

[0038] According to one embodiment, the through-structure comprises a plurality of sealed pipes successively passing through the external portion, the internal space and the internal portion of the main casing and opening into the internal space of the tank.

[0039] According to one embodiment, the plurality of sealed pipes successively passing through the external portion has one or more characteristics mentioned for the sealed pipe.

[0040] The plurality of sealed pipes may include pipes having the same or different characteristics.

[0041] According to one embodiment, the plurality of sealed pipes comprises between 2 and 10 sealed pipes, preferably between 3 and 7, for example 4, 5 or 6 pipes.

[0042] According to one embodiment, a stiffener extends across the interior space of the main envelope between the inner portion and the outer portion, the stiffener being attached to said inner portion and said outer portion of the main envelope.

[0043] Thanks to these characteristics, the deflection of the internal and external portion under the effect of pressure is reduced.

[0044] According to one embodiment, the stiffener comprises a rigid core connecting the internal portion and the external portion. According to one embodiment, the core is made of a composite with low thermal conductivity.

[0045] According to one embodiment, the interior space of the main envelope is lined with thermal insulation, preferably chosen from glass wool, perlite and multi-layer insulation.

[0046] According to one embodiment, the gas phase of the primary thermally insulating barrier is at an absolute pressure of less than 1 Pa, advantageously less than 10 -1 Pa, preferably less than 10 –2 Pa and for example of the order of 10 -3 Pa.

[0047] According to one embodiment, the internal portion of the main envelope has a curved shape.

[0048] According to one embodiment and according to a view from the internal space of the tank, the internal portion of the main casing has a convex shape whose apex is located in the internal space.

[0049] Thanks to these characteristics, the deflection of the internal portion under pressure is reduced.

[0050] According to one embodiment, the liquefied gas is liquid hydrogen (LH2).

[0051] According to one embodiment, the primary waterproof membrane has a flat peripheral portion located around the passage and fixed to the internal collar all around said passage, preferably by welding.

[0052] According to one embodiment, the primary waterproof membrane is welded against an internal face of the internal peripheral fixing element, preferably of the internal collar.

[0053] According to one embodiment, the primary waterproof membrane is welded against an external face of the internal peripheral fixing element, preferably of the internal collar.

[0054] According to one embodiment, the through structure is made entirely or partly of Invar® or stainless steel.

[0055] According to one embodiment, the primary waterproof membrane is corrugated.

[0056] According to one embodiment, the primary waterproof membrane and / or the secondary waterproof membrane comprises a plurality of corrugated metal sheets, each corrugated metal sheet having edges which are each lap welded to an edge of an adjacent corrugated metal sheet.

[0057] Such a liquefied gas storage facility 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.

[0058] According to one embodiment, a ship for transporting liquefied gas comprises a double hull and a liquefied gas storage facility provided in the double hull.

[0059] 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 liquefied gas storage installation installed in the hull of the vessel to a floating or land-based storage installation.

[0060] According to one embodiment, the transfer system also 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 ship's liquefied gas storage facility.

[0061] 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 liquefied gas storage facility of the vessel. Brief description of the figures

[0062] 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.

[0063] This is a partial sectional view along the thickness direction of a liquefied gas storage facility according to a first embodiment.

[0064] This is a partial enlarged perspective view of a through structure according to the first embodiment.

[0065] This is a partial sectional view along the thickness direction of a liquefied gas storage facility according to a second embodiment.

[0066] This is a schematic cutaway representation of a ship's tank and a loading / unloading terminal for this tank.

[0067] 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 liquefied gas storage facility.

[0068] 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.

[0069] Figures 1 and 2 illustrate a first embodiment of the through-structure 9 of the liquefied gas storage installation 1. 1 presents a second embodiment of the through-structure 109 of the liquefied gas storage installation 100.

[0070] On the, the elements identical or similar to those illustrated in figures 1 and 2 bear the same reference number incremented by 100.

[0071] In relation to Figures 1 to 3, the liquefied gas storage facility according to embodiments comprises a supporting structure and a sealed and thermally insulating tank installed in the supporting structure.

[0072] The supporting structure may, in particular, be formed of self-supporting metal sheets or, more generally, of any type of rigid partition with suitable mechanical properties. The supporting structure is, for example, formed by the double hull of a ship.

[0073] For example, in Figures 1 to 3, the liquefied gas storage installation 1, 101 comprises a supporting structure comprising a ceiling supporting wall 2, 102 forming part, for example, of the deck of a ship, and a sealed and thermally insulating tank 3, 103.

[0074] The sealed and thermally insulating tank 3, 103 comprises a plurality of tank walls forming, for example, a tank of generally polyhedral shape (not shown), such as an octagonal shape.

[0075] The tank wall has a multi-layer structure comprising, along the thickness direction E of the tank wall, from the outside to the inside, a secondary thermally insulating barrier 4, 104, a secondary sealed membrane 5, 105, a primary thermally insulating barrier 6, 106 and a primary sealed membrane 7, 107 intended to be in contact with the liquefied gas contained in the tank, the primary sealed membrane 7, 107 delimiting an internal space 8, 108 of the tank 3 intended to contain a liquefied gas, such as liquefied hydrogen. This multi-layer structure can be produced in many ways.

[0076] The secondary waterproof membrane 5, 105 has corrugations and more particularly a first series of corrugations extending parallel to a first direction and a second series of corrugations extending parallel to a second direction. The directions of the series of corrugations are perpendicular to each other. Each of the series of corrugations is parallel to two opposite edges of the corrugated metal sheet. The corrugations here protrude towards the inside of the tank, that is to say towards the internal space 8, 108 of the tank 3, 103. The secondary waterproof membrane 5, 105 comprises between the corrugations, a plurality of flat zones.

[0077] The primary waterproof membrane 7, 107 may have the same characteristics as the secondary waterproof membrane 5, 105.

[0078] The pitch of the corrugations of the secondary waterproof membrane 5, 105 is equal to the pitch of the corrugations of the primary waterproof membrane 7, 107 or to an integer multiple thereof. In addition, each of the corrugations of the secondary waterproof membrane 5, 105 is arranged opposite, in the thickness direction of the wall, a corrugation of the primary waterproof membrane 7, 107. Thus, each flat area of ​​the primary waterproof membrane 7, 107 is located opposite, in the thickness direction of the wall of the tank, a flat area of ​​the secondary waterproof membrane 5, 105. Therefore, the secondary waterproof membrane 5, 105 and the primary waterproof membrane 7, 107 are anchored, by welding, on load-bearing elements at the level of their flat area, for example by spot welds.

[0079] Furthermore, the primary thermally insulating barrier 6, 106 has a gas phase which is under vacuum, i.e. has an absolute pressure lower than atmospheric pressure, in order to give the primary thermally insulating barrier 6, 106 the required thermally insulating properties. The gas phase of the primary thermally insulating barrier 6, 106 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 -3 Pa. To do this, the primary thermally insulating barrier 6, 106 is advantageously connected to a vacuum pump.

[0080] A first embodiment of the through structure 9 of the liquefied gas storage installation 1 illustrated in Figures 1 and 2 will now be described.

[0081] The through structure 9 is positioned in a passage provided through the ceiling load-bearing wall 2 and the tank wall, i.e. passing through the secondary thermally insulating barrier 4, the secondary waterproof membrane 5, the primary thermally insulating barrier 6 and the primary waterproof membrane 7. The through structure 9 fills said passage.

[0082] The through structure 9 comprises a main casing 10 positioned in the passage, the main casing 10 is formed by a plurality of walls and delimits in a sealed manner an interior space 11 under vacuum. The interior space 11 of the main casing 10 contains a gaseous phase at an absolute pressure of less than 10 Pa, for example less than 1 Pa, less than 10 –2 Pa or less than 10 –3 Pa.

[0083] This interior space may also include thermal insulation such as glass wool, perlite or a material designated by the acronym MLI for “multi-layer insulation”, for example the interior space is filled with perlite.

[0084] The through structure 9 is fixed in the passage via an external collar 12 which projects from an external portion, that is to say from a portion projecting towards the outside of the tank 3 from the ceiling load-bearing wall 2 of the through structure 9. The external collar 12 is welded to the ceiling load-bearing wall 2 all around the passage.

[0085] A secondary closure wall 20 extends around the central portion of the main envelope 10 between the ceiling load-bearing wall 2 and the primary waterproof membrane 7 of the main envelope 10 and at a distance from the main envelope 10. The secondary closure wall 20 connects the external collar 12 to the secondary waterproof membrane 5 via a fixing zone 21, for example in the shape of a “U” to close the secondary thermally insulating barrier 4 all around said passage in a sealed manner and to form an intermediate space 40 between the secondary closure wall 20 and the central portion of the main envelope 10. The intermediate space 40 is in communication with the primary thermally insulating barrier 6. Thus, the gas phase of the intermediate space is identical to the gas phase of the primary thermally insulating barrier 6, i.e. an absolute pressure of less than 1 Pa, for example less than 10 –2 Pa.

[0086] The “U”-shaped fixing zone 21 comprises, for example, a metal part onto which the secondary waterproof membrane 5 is welded on a first surface and a portion of the secondary closing wall 20 on a second surface opposite the first surface.

[0087] The sealing at the passage between the internal space 8 of the tank 3 and the primary thermally insulating barrier 6 is ensured by an internal collar 13 which projects from a lower portion of the main casing 10 on which the primary waterproof membrane 7 is welded, all around said internal collar 13. For example, this illustrates a weld of the waterproof membrane 7 against an internal face of the internal collar 13.

[0088] The primary waterproof membrane 7 has a flat fixing zone, that is to say an area of ​​the primary waterproof membrane 7 which does not have any undulation and which is welded to the internal collar 13.

[0089] Sealed pipes 16, for example four in number on the, pass through the main casing 10 from one side to the other in the thickness direction E, passing through the interior space 11.

[0090] The main casing 10 comprises a bottom wall 14 in contact with the internal space 8. The bottom wall 14 projects into the internal space 8 and closes the main casing 10 at an internal end of the main casing 10.

[0091] The bottom wall 14 comprises two internal anchor cylinders 15 located at a distance from each other which project towards the internal space 8 of the tank. The two sealed pipes 16 are respectively fixed in a sealed manner to an internal anchor cylinder 15 all around said internal anchor cylinder 15.

[0092] The two internal anchor cylinders 15 have different dimensions from each other. According to a variant, the two internal anchor cylinders 15 have identical dimensions. The dimensions of an anchor cylinder 15 are chosen so as to be suitable for receiving and fixing a pipe 16 in a sealed manner.

[0093] For the sake of clarity, only two sealed pipes 16 have been illustrated, other pipes such as those shown in the have been omitted in the.

[0094] The sealed pipes 16 each comprise a double peripheral wall 17 extending from the interior space 11 of the main casing 10 to the exterior of the liquefied gas storage facility 9. The double peripheral wall 17 forms a peripheral space which is in communication with the interior space 11 of the main casing. Thus, the peripheral space has a pressure identical to the pressure of the interior space 11 of the main casing 10. The double peripheral wall 17 makes it possible to increase the thermal insulation of the sealed pipes 16.

[0095] According to a variant not shown, the double peripheral wall forms an internal space which is not in communication with the interior space 11. In this case, the pressure of the gas phase in the peripheral space may be identical to or different from the pressure of the gas phase in the interior space 11 of the main casing 10.

[0096] The main casing 10 comprises a ceiling wall 18 located at a distance from the collar 12 towards the outside of the tank and a wall 22 perpendicular to the ceiling wall, connecting the ceiling wall 18 to the collar 12, all around the collar 12.

[0097] The ceiling wall 18 is crossed by the sealed pipes 16. The sealed pipes 16 are each connected to the ceiling wall 18 by a compensation bellows 19 in order to take up variations in length resulting from thermal contraction, for example during the loading and unloading of liquefied gas from the internal space 8 of the tank 3 which generates significant variations in temperature.

[0098] The main casing 10 further comprises a second wall which has the shape of a broken line comprising an outgoing portion 23, a plate 24 and a re-entering portion 25. This second wall is arranged to close the intermediate space at an external portion of the main casing 10.

[0099] The outgoing portion 23 projects towards the outside of the tank from a portion of the external collar 12 located inside the passage and forming a portion of the main casing 10. The outgoing portion 23 is located opposite the secondary closing wall 20 relative to the external collar 12.

[0100] The tray 24 extends from the outgoing portion 23, towards the inside of the passage. The tray 24 is perpendicular to the central portion 23, parallel to the ceiling wall 18 and located at a distance from the ceiling wall 18.

[0101] The re-entrant portion 25 extends perpendicularly from the plate 24, parallel to the outgoing portion 23 and to the closing wall 20, towards the interior of the tank 3 in the thickness direction and extends in the form of a side wall of the main casing 10 until it connects the bottom wall 14.

[0102] According to a second embodiment illustrated with the, the liquefied gas storage installation 101 differs from the first embodiment in that the main casing 110 has a cylindrical shape and that the ceiling wall 118 and the bottom wall 114 have a convex shape seen from the outside of the main casing 110. Thanks to these characteristics, the deflection of the internal portion comprising the bottom wall 114 and of the external portion comprising the ceiling wall of the main casing 110 is reduced.

[0103] Further, the ceiling wall 118 is connected to the outer collar 112 via an outer peripheral casing which extends from the ceiling wall 118 of the main casing 110, around the ceiling wall 118 and is arranged to close the intermediate space 140.

[0104] The outer peripheral casing comprises a first wall 26 projecting outwardly from the ceiling wall 118, all around the main casing 110 and a second wall 27 connecting the first wall 26 to the outer collar 112, all around the outer collar 112.

[0105] With reference to the, a cutaway view of a ship 70 shows a liquefied gas storage installation 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealed membrane intended to be in contact with the liquefied gas, preferably liquid hydrogen, contained in the internal space of the tank, a secondary sealed membrane arranged between the primary sealed membrane and the double hull 72 of the ship, and two thermally insulating barriers arranged respectively between the primary sealed membrane and the secondary sealed membrane and between the secondary sealed membrane and the double hull 72.

[0106] 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 liquefied gas storage facility 71.

[0107] 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 vessel sizes. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the ship 70 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 vessel 70 at a great distance from the coast during loading and unloading operations.

[0108] 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 internal space of the tank under the effect of the evaporation of the liquefied gas stored in the tank.

[0109] 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.

[0110] 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.

[0111] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

[0112] 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 just 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 their wording and the prediction of which is within the reach of those skilled in the art based on their general knowledge.

Claims

Liquefied gas storage installation comprising a supporting structure and a sealed and thermally insulating tank installed in the supporting structure, the supporting structure comprising a ceiling supporting wall (2, 102), the sealed and thermally insulating tank comprising a tank wall fixed to the ceiling supporting wall, the tank wall successively comprising, in a thickness direction from the outside of the tank, a secondary thermally insulating barrier (4, 104), a secondary sealed membrane (5, 105), a primary thermally insulating barrier (6, 106) and a primary sealed membrane (7, 107) delimiting an internal space (8, 108) of the tank intended to contain a liquefied gas, said liquefied gas storage installation (1, 101) comprising a through structure (9, 109) carried by the ceiling supporting wall and positioned in a passage provided through the ceiling supporting wall and the tank wall,the through structure comprising:a main envelope (10, 110) sealingly delimiting an interior space (11, 111), said main envelope comprising:- a central portion extending in the thickness direction between the ceiling load-bearing wall and the primary waterproof membrane,- an internal portion in contact with the internal space,- an external portion projecting towards the outside of the tank from the ceiling load-bearing wall,said interior space (11, 111) containing a gas phase at an absolute pressure of less than 10 Pa,an external peripheral fixing element connecting the external portion of the main envelope to the ceiling load-bearing wall all around said passage,a secondary closing wall (20, 120) extending around the central portion of the main envelope at a distance from the central portion,the secondary closing wall sealingly connecting the external peripheral fixing element to the secondary waterproof membrane (5, 105) to close the secondary thermally insulating barrier all around said passage and to form an intermediate space (40) between the secondary closing wall (20, 120) and the central portion of the main casing (10, 110), the intermediate space being in communication with the primary thermally insulating barrier (6, 106), an internal peripheral fixing element which projects outwards from the internal portion or the central portion, the primary waterproof membrane (7, 107) being sealed to the internal peripheral fixing element all around the main casing, and a sealed pipe (16, 116) successively passing through the external portion, the internal space and the internal portion of the main casing (10, 110) and opening into the internal space,an internal portion of the watertight pipe being fixed to the internal portion of the main casing., Liquefied gas storage facility according to claim 1, wherein the external peripheral fixing element comprises an external collar (12, 112) fixed to the ceiling load-bearing wall all around said passage. Liquefied gas storage facility according to claim 2, wherein the outer peripheral fixing element comprises an outer peripheral casing (26, 27) connecting the outer portion of the main casing to the outer collar (112). A liquefied gas storage facility according to claim 3, wherein the outer peripheral casing (26, 27) extends from the outer portion of the main casing, around the outer portion of the main casing and is arranged to close the intermediate space (40). Liquefied gas storage installation according to claim 2, in which the external collar (12) extends parallel to the ceiling load-bearing wall inside the passage and has a first portion forming part of the main casing and a second portion projecting outside the main casing to connect the main casing to the ceiling load-bearing wall all around said passage, the external portion of the main casing comprising: - a first wall (22) projecting towards the outside of the tank from the first portion of the external collar, - a second wall located at a distance from the first wall towards the inside of the passage and arranged to close the intermediate space,the second wall having a broken line shape comprising an outgoing portion (23) projecting towards the outside of the tank from the first portion of the external collar and a re-entrant portion (25) extending from the outgoing portion towards the inside of the tank in the thickness direction., Liquefied gas storage installation according to one of claims 1 to 5, in which the main casing has a shape of revolution, and in which the central portion comprises a side wall (125) having an inner end and an outer end, the inner portion comprises a bottom wall (114) closing the inner end of the side wall (125) and being crossed by the sealed pipe, and the outer portion comprises a cover wall (118) closing the outer end of the side wall (125) and being crossed by the sealed pipe. Liquefied gas storage installation according to one of claims 1 to 6, in which an external portion of the sealed pipe (16, 116) is connected in a sealed manner to an external surface of the external portion of the main casing by a compensation bellows (19, 119), the compensation bellows being intended to take up variations in length resulting from thermal contraction. Liquefied gas storage installation according to claim 1 to 7, in which the through structure comprises an internal anchoring cylinder (15, 115) projecting from the internal portion of the main casing towards the internal space of the tank, the sealed pipe (16, 116) being fixed in a sealed manner to said internal anchoring cylinder. Liquefied gas storage installation according to claim 1 to 8, in which the sealed pipe (16) comprises a double peripheral wall (17) enclosing a peripheral vacuum space, the peripheral vacuum space preferably being at a pressure lower than 10 Pa, and even more preferably at a pressure lower than 1 Pa. Liquefied gas storage installation according to one of claims 1 to 9, in which the through structure comprises a plurality of sealed pipes successively passing through the external portion, the internal space and the internal portion of the main casing and opening into the internal space of the tank. A liquefied gas storage facility according to any one of claims 1 to 10 wherein a stiffener (50) extends across the interior space of the main casing between the inner portion and the outer portion, the stiffener being secured to said inner portion and to said outer portion of the main casing. Liquefied gas storage installation according to one of claims 1 to 11 in which the interior space (11, 111) of the main envelope is lined with thermal insulation, preferably chosen from glass wool, perlite and multi-layer insulation. Liquefied gas storage installation according to one of claims 1 to 12, in which the gas phase of the primary thermally insulating barrier (6, 106) is at an absolute pressure of less than 1 Pa. A ship (70) for transporting liquefied gas, the ship comprising a double hull (72) and a liquefied gas storage facility (71) according to one of claims 1 to 13 arranged in the double hull. A transfer system for liquefied gas, the system comprising a vessel (70) according to claim 14 and insulated pipelines (73, 79, 76, 81) arranged to connect the liquefied gas storage facility (71) installed in the hull of the vessel to a floating or land-based storage facility (77). A method of loading or unloading a ship (70) according to claim 14, wherein a liquefied gas is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the liquefied gas storage facility (71) of the ship (70).

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