Liquefied gas storage facility with a dome structure

Abstract

The invention relates to a liquefied gas storage facility comprising: a supporting structure (1); a sealed and thermally insulating tank; and a dome structure (25) comprising: - an inner barrel (29) passing through an opening (27) provided in the supporting structure (1); - an outer barrel (26) arranged around the barrel (29), the outer barrel (26) being fixed to the supporting structure (1) around an annular portion (34) of the supporting structure (1); and - a secondary exhaust duct (61) opening into the secondary space (52); in which the annular portion (34) of the supporting structure (1) comprises a plurality of through-holes (38) which are distributed around the annular passage portion and allow gas to circulate from the secondary thermally insulating barrier (12) to the secondary space (52). Figure for the abstract: 4

Description

Title of the invention: Liquefied gas storage facility comprising a dome structure Technical field

[0001] The invention relates to the field of installations for the storage and / or transport of a liquefied gas, such as installations for the transport of Liquefied Petroleum Gas (also called LPG) having, for example, a temperature between -50°C and 0°C, or for the transport of Liquefied Natural Gas (LNG) at approximately -162°C at atmospheric pressure.

[0002] These installations can be installed on land or on a floating structure. In the case of a floating structure, the installation can be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the floating structure.

[0003] The invention relates more particularly to an installation of the aforementioned type comprising a tank and a dome structure which passes through a ceiling wall of the tank. Technological background

[0004] Document WO2019030447 discloses a dome structure passing through a wall ceiling of a Liquefied Natural Gas storage tank. The dome structure thus defines a passage between the interior space of the tank and a steam collector arranged outside the tank. The dome structure comprises an inner barrel which passes through the double shell as well as the ceiling wall of the tank and which is welded in a watertight manner to the primary waterproofing membrane of the ceiling wall. An outer barrel arranged around said inner barrel is fixed to the inner shell of the double shell. The dome structure also comprises a sheath which is arranged radially between the outer barrel and the inner barrel and which is connected in a watertight manner to the secondary waterproofing membrane. A primary space communicating with the primary thermally insulating barrier is provided between the sheath and the inner barrel.A primary exhaust device is connected to the primary space and thus allows gas to be evacuated from the primary thermally insulating barrier of the tank, which protects the primary sealing membrane against overpressure. The dome structure also includes a primary inerting duct which opens into the primary space. An insulating gasket made of polymer foam is housed in the primary space all around the sheath. The insulating gasket is provided with a through passage allowing the primary exhaust device duct to communicate with the primary thermally insulating barrier.

[0005] The inner shell has around the sheath an annular passage allowing the gas present in the secondary thermally insulating barrier to flow towards a secondary space of the dome structure which is arranged radially inside the outer barrel. A secondary exhaust device is connected to the secondary space and thus allows gas to be evacuated from the secondary thermally insulating barrier, which makes it possible to protect the secondary sealing membrane against overpressures. The dome structure also comprises a secondary inerting conduit which opens into the secondary space. Opposite the annular passage, the secondary thermally insulating barrier comprises glass wool all around the sheath.

[0006] Such a dome structure is not entirely satisfactory. Indeed, the inventors have found that, when inert gas containing a little moisture has penetrated into the secondary thermally insulating barrier, the water it contains is likely to be absorbed by the glass wool which is arranged all around the sheath and to solidify in the form of ice. In such circumstances, the ice hinders the circulation of gas through the glass wool, and consequently hinders the escape of gas from the secondary thermally insulating barrier.

[0007] Furthermore, when the tank is cooled, the polymer foam insulating lining which is positioned in the primary space contracts and generates gaps which are detrimental to the thermal insulation performance in the primary space. Summary of the invention

[0008] An idea underlying the invention is therefore to propose a liquefied gas storage facility comprising a dome structure of the aforementioned type which is equipped with a secondary exhaust device enabling gas to be reliably evacuated from the secondary thermally insulating barrier.

[0009] According to a first aspect, the invention provides a liquefied gas storage facility comprising: a supporting structure; a sealed and thermally insulating tank, intended to store a liquefied gas, comprising an upper wall having successively in a thickness direction, at least one secondary thermally insulating barrier resting against the supporting structure and a secondary sealing membrane resting against the secondary thermally insulating barrier; and a dome structure comprising: - an inner barrel passing through an opening made in the supporting structure and passing through the upper wall of the tank; - an outer barrel arranged around the inner barrel and providing a secondary space radially between the inner barrel and the outer barrel, said secondary space comprising communicating with the secondary thermally insulating barrier by an annular passage part which is arranged, in the opening, radially outside the inner barrel, the outer barrel being fixed to the supporting structure around an annular portion of the supporting structure which borders said annular passage part; and - a secondary exhaust device intended to evacuate a fluid from the secondary thermally insulating barrier comprising a secondary exhaust duct opening into the secondary space; wherein the annular portion of the supporting structure comprises a plurality of through-holes which are distributed around the annular passage portion and allow gas to circulate from the secondary thermally insulating barrier to the secondary space.

[0010] Thus, such through-lights provide an additional path for the gas to flow from the secondary thermally insulating barrier to the secondary space. Therefore, even if the passage of the gas through the annular passage portion of the opening were to be blocked by the formation of ice in a porous material arranged opposite the annular passage portion, sufficient circulation of gas from the secondary thermally insulating barrier to the secondary space would remain possible.

[0011] According to embodiments, such a liquefied gas storage facility may comprise one or more of the following characteristics.

[0012] According to one embodiment, the secondary exhaust duct passes through the outer barrel.

[0013] According to one embodiment, the secondary exhaust duct is connected to a valve which, by default, is closed and which opens when the pressure in the primary thermally insulating barrier exceeds a predetermined threshold pressure.

[0014] According to one embodiment, the dome structure comprises a secondary inerting conduit which opens into the secondary space.

[0015] According to one embodiment, the secondary inerting conduit passes through the outer barrel.

[0016] According to one embodiment, the secondary inerting conduit is connected to a tank and / or a generator of inert gas, such as nitrogen, by a compressor.

[0017] According to one embodiment, the secondary thermally insulating barrier comprises secondary insulating panels which rest against the supporting structure by means of a plurality of mastic beads, said plurality of mastic beads defining interstices between the secondary insulating panels and the supporting structure. This further facilitates the evacuation of the gas through the through-holes.

[0018] According to one embodiment, the secondary thermally insulating barrier comprises one or more elements made of porous materials, arranged outside the inner barrel and opposite the annular passage part. This facilitates the circulation of gas from the secondary thermally insulating barrier to the secondary space, provided that ice has not formed in said elements made of porous material.

[0019] According to one embodiment, the outer barrel and the inner barrel are anchored to each other by an upper anchoring device and a lower anchoring device, the exhaust duct opening into the secondary space between the upper anchoring device and the lower anchoring device, the lower anchoring device being equipped with passages allowing gas to circulate through said lower anchoring device.

[0020] According to one embodiment, the lower anchoring device comprises a frustoconical support element which flares downwards and is fixed to the inner barrel, a support collar which is fixed to the frustoconical support element and projects radially outwards and an annular flange which is fixed to the outer barrel and projects radially inwards of said outer barrel, the support collar being supported by the annular flange.

[0021] According to one embodiment, the truncated conical support element has holes.

[0022] According to one embodiment, at least two of the holes formed in the element truncated support cones are respectively crossed by a primary exhaust duct and by a primary inerting duct which open into the primary space communicating with the primary thermally insulating barrier.

[0023] According to one embodiment, a shim is interposed between the support collar and the annular flange.

[0024] According to one embodiment, the wedge has slots allowing the circulation of gas through said lower anchoring device.

[0025] According to another embodiment, the wedge interposed between the support collar and the annular flange is composed of several pieces with a spacing between them allowing the circulation of gas through said lower anchoring device.

[0026] According to one embodiment, the upper wall has a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane resting against the primary thermally insulating barrier and intended to be in contact with the liquefied gas stored in the tank.

[0027] According to one embodiment, the inner barrel is welded in a sealed manner to the primary sealing membrane.

[0028] According to one embodiment, the liquefied gas storage facility comprises: - a sheath which is arranged around the inner barrel, said sheath comprising a lower end which is connected in a sealed manner to the secondary sealing membrane; said sheath being connected in a sealed manner to the inner barrel so as to providing a primary space between the sheath and the inner barrel; said primary space communicating with the primary thermally insulating barrier; and - a primary exhaust duct and a primary inerting duct which open into the primary space.

[0029] According to one embodiment, the primary exhaust duct is connected to a valve which, by default, is closed and which opens when the pressure in the primary thermally insulating barrier exceeds a predetermined threshold pressure.

[0030] According to one embodiment, the primary inerting conduit is connected to a tank and / or a generator of inert gas, such as nitrogen, by a compressor.

[0031] According to one embodiment, an insulating lining is housed in the sheath, said insulating lining having an annular shape and comprising: - at least two polymer foam sectors, each comprising a through orifice connected to the primary exhaust duct and to the primary inerting duct; and - at least one sector of porous material force-fitted into each space between two adjacent polymer foam sectors.

[0032] Such a structure is advantageous in that it allows the gas to circulate reliably between the primary thermally insulating barrier and the primary inerting and exhaust ducts because the orifices formed in two polymer foam sectors are not likely to be blocked by ice as are the pores of a porous material. Furthermore, the angular sectors of porous material mounted in a compressed state make it possible to compensate for the thermal contraction of the angular sectors of polymer foam and thus contribute to obtaining excellent thermal insulation performance.

[0033] According to one embodiment, the polymer foam sectors are made of polyurethane foam.

[0034] According to one embodiment, the sectors made of porous material are made of a material chosen from glass wool, rock wool and polyester wadding.

[0035] Such an installation may be part of a land-based storage facility, for example for storing LNG, or may be installed in a floating, coastal, or deep-water structure, including an LNG 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.

[0036] According to one embodiment, a ship for transporting a liquefied gas comprises a storage installation for a liquefied gas of the aforementioned type.

[0037] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned vessel, insulated pipes arranged to connect the vessel's liquefied gas storage facility tank to a floating or land-based storage facility and 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's liquefied gas storage facility tank.

[0038] According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the tank of the liquefied gas storage facility of the ship.

[0039] According to a second aspect capable of being implemented independently of the first aspect, the invention also provides a liquefied gas storage facility comprising: a supporting structure; a sealed and thermally insulating tank, intended to store a liquefied gas, comprising an upper wall having successively in a thickness direction, at least one secondary thermally insulating barrier resting against the supporting structure, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane resting against the primary thermally insulating barrier and intended to be in contact with the liquefied gas stored in the tank; and a dome structure comprising: - an inner barrel passing through an opening made in the supporting structure and passing through the upper wall of the tank, the inner barrel being welded in a watertight manner to the primary waterproofing membrane; - an outer barrel arranged around the inner barrel, the outer barrel being fixed to the supporting structure around the opening made in the supporting structure; and - a sheath which is arranged around the inner barrel, said sheath having a lower end which is connected in a sealed manner to the secondary sealing membrane; said sheath being connected in a sealed manner to the inner barrel so as to provide a primary space between the sheath and the inner barrel; said primary space communicating with the primary thermally insulating barrier; - a primary exhaust duct and a primary inerting duct which open into the primary space; and - an insulating lining which is housed in the sheath, said insulating lining having an annular shape and comprising at least two sectors made of polymer foam each comprising a through orifice connected to the primary exhaust duct and to the primary inerting duct; and at least one sector made of porous material force-fitted into each space between two adjacent polymer foam sectors. Brief description of the figures

[0040] The invention will be better understood, and other aims, 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 appended drawings.

[0041] [Fig.l] is a schematic perspective view of a supporting structure intended to support a sealed and thermally insulating tank for storing liquefied gas, the dome structure not being shown.

[0042] [Fig.2] is a schematic view of the multi-layer structure of the tank walls.

[0043] [Fig. 3] is a sectional view of a dome structure, according to a method of rea lization, passing through a ceiling wall of a sealed and thermally insulating tank.

[0044] [Fig.4] is a detailed view of the tank ceiling wall and dome structure of [Fig.3].

[0045] [Fig. 5] is a perspective view of an insulating gasket according to an advantageous embodiment, intended to be positioned inside the sheath of the dome structure illustrated in Figures 3 and 4.

[0046] [Fig. 6] is a top view of the lower anchoring device for anchoring the inner barrel to the outer barrel in the dome structure illustrated in Figures 3 and 4.

[0047] [Fig. 7] is a cutaway schematic representation of a ship comprising a liquefied natural gas storage tank and a terminal for loading / unloading this tank. Description of the embodiments

[0048] In connection with [Fig.l], a supporting structure 1 is described against which a sealed and thermally insulating tank for storing a liquefied gas is intended to be fixed. The supporting structure 1 is, for example, formed by the double hull of a ship. The double hull comprises an outer hull 19 and an inner hull 18 arranged inside the outer hull 19. The supporting structure 1 has a generally polyhedral shape. It has two front and rear supporting walls, here octagonal in shape, of which only the rear supporting wall 2 is shown in [Fig.l]. 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 supporting wall 3, a lower supporting wall 4 and side supporting walls 5, 6, 7, 8, 9, 10.The sealed and thermally insulating tank for storing liquefied gas comprises a plurality of tank walls which are each anchored against one of the load-bearing walls 2, 3, 5, 6, 7, 8, 9, 10 of. the supporting structure 1 and which thus define an internal space intended to contain the liquefied gas.

[0049] As shown in [Fig.2], each wall of the tank successively presents, from the outside to the inside, according to the direction of thickness of the wall: - a secondary thermally insulating barrier 12 comprising insulating elements 13 fixed to the supporting structure 1; - a secondary sealing membrane 14 anchored to the insulating elements 13 of the secondary thermally insulating barrier 12; - a primary thermally insulating barrier 15 comprising insulating elements 16 fixed to the insulating elements 13 of the secondary thermally insulating barrier 12 or to the supporting structure 1 and resting against the secondary sealing membrane 14; and - a primary sealing membrane 17 anchored to the insulating elements 16 of the primary thermally insulating barrier 15 and intended to be in contact with the liquefied gas contained in the tank.

[0050] The liquefied gas intended to be stored in the tank may in particular be ethane, liquefied natural gas (LNG), i.e. a gas mixture comprising mainly methane and one or more other hydrocarbons, or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons resulting from the refining of petroleum comprising essentially propane and butane.

[0051] In the embodiment shown in Figures 3 and 4, the insulating elements of the secondary thermally insulating barrier 12 are secondary insulating panels 20 comprising a layer of insulating polymer foam 21, for example polyurethane, sandwiched between a cover plate 22 and a rigid base plate 23, for example plywood.

[0052] The secondary sealing membrane 14 is formed from a continuous sheet of strakes with raised edges. Each strake has a flat central portion resting on the cover plate of the secondary insulating panels 20 and two raised edges projecting towards the inside of the tank. The strakes are welded by their raised edges to welding supports which are fixed in the grooves provided on the cover plates 22 of the secondary insulating panels 20. The strakes 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 x 106 K1 and 2.0 x 106 K1. It is also possible to use alloys of iron and manganese whose coefficient of expansion is typically of the order of 7 x 106 K 1 to 10 x 10 6 K *.

[0053] The insulating elements of the primary thermally insulating barrier 15 are primary insulating panels 24 comprising a layer of insulating polymer foam, for example polyurethane, sandwiched between a cover plate and a rigid bottom plate, for example made of plywood.

[0054] The primary sealing membrane 17 is obtained by assembling a plurality of corrugated metal sheets, welded to each other overlapping along their edges. The corrugations project towards the inside of the tank. The corrugated metal sheets are fixed on anchoring strips which are fixed in counterbores provided in the cover plates of the primary insulating panels 24. The corrugated metal sheets are, for example, made of stainless steel or aluminum.

[0055] Alternatively, the walls of the tank can also be produced according to the technologies described in patent applications WO14057221, FR2691520 and FR2877638 relating respectively to the Mark V, Mark III® and NO96® products developed by the applicant.

[0056] In relation to Figures 3 and 4, a dome structure 25 is described below according to one embodiment. The dome structure 25 comprises an outer barrel 26, of cylindrical shape which extends in the direction of thickness of the ceiling wall of the tank. The outer barrel 26 passes through an opening made in the outer shell 19. The lower end of the outer barrel 26 is welded in a sealed manner to the inner shell 18, around an opening 27 formed in said inner shell 18. The inner shell 18 therefore comprises an annular portion 34 which borders the opening 27 and is arranged radially inside the outer barrel 26.

[0057] The upper end of the outer barrel 26 is sealed by a removable cover 28.

[0058] The dome structure 25 also comprises an inner barrel 29 which is disposed inside the outer barrel 26. The inner barrel 29 is concentric with the outer barrel 26 and passes through the opening 27 formed in the inner shell 18. The inner barrel 29 also passes through the upper wall of the tank. The inner barrel 29 has a lower end which is sealed to the primary sealing membrane 17 so as to seal the primary thermally insulating barrier 15 against the interior space of the tank. The inner barrel 29 is open at each of its two ends. The outer barrel 26 and the inner barrel 29 are anchored to each other by an upper anchoring device 31 and a lower anchoring device 32.

[0059] The upper anchoring device 31 comprises a support collar 50 which is fixed to the inner barrel 29 and projects radially outwards around it, as well as an annular flange 51 which is welded to the outer barrel 26 and projects radially inwards therefrom. The support collar 50 rests against the annular flange 51. The support collar 50 and the annular flange 51 are welded to each other in a sealed manner. Thus, a secondary space 52 is provided between the outer barrel 26 and the inner barrel 29, below said support collar 50 and flange annular 51. Below the upper anchoring device 31, an insulation layer 65 is distributed uniformly over the outer span of the inner barrel 29.

[0060] In the embodiment shown, the inner barrel 29 is fixed to the support collar 50 by means of a compensation device, visible in [Fig. 3], allowing the inner barrel 29 to contract or expand. The compensation device here comprises a metal tube which has a plurality of bellows and which is, on the one hand, fixed to the inner barrel 29 and, on the other hand, fixed to the support collar 50.

[0061] The lower anchoring device 32 comprises a frustoconical support element 53 which flares downwards and which is welded to the inner barrel 29 around it. It also comprises a support ring which is welded to the radially outer edge of the frustoconical support element 53 and which comprises a support collar 54 which projects radially outwards. The lower anchoring device 32 also comprises an annular flange 55 which is welded to the outer barrel 26 and projects radially inwards thereof. The support collar 54 rests on the annular flange 55 directly or indirectly via a shim 56 interposed between said support collar 54 and said annular flange 55 as in the embodiment shown. The shim 56 is, for example, made of wood. It is fixed against the support collar 54 and against the annular flange 55, for example by bolting and / or by gluing using resin or glue.Advantageously, the thickness of the shim 56 is determined in order to compensate for the manufacturing and / or positioning tolerances of the inner barrel 29 relative to the outer barrel 26 in the direction of thickness of the ceiling wall of the tank.

[0062] The dome structure 25 also comprises a conduit 33 which is concentric with the inner barrel 29 and passes through it. This conduit 33 makes it possible in particular to conduct the vapor phase of the liquefied gas stored in the tank, from the internal space of the tank to a collection zone 35 positioned at the upper end of the dome structure 25. The dome structure 25 also comprises at least one vapor collection conduit 63 which passes in a sealed manner through the wall of the outer barrel 26 and opens into the collection zone 35. Thus, the vapor collection conduit(s) 63 are capable of conducting vapor between the collection zone 35 and a vapor collector, not shown, arranged outside the dome structure 25.

[0063] The dome structure 25 further comprises a sheath 57, visible in FIGS. 3 and 4, which is concentric with the outer barrel 26 and which is arranged radially between the outer barrel 26 and the inner barrel 29. The sheath 57 also passes through the opening 27 formed in the inner shell 18. The upper end of the sheath 57 is sealed welded to an upper annular plate 30 which is also sealed welded to the inner barrel 29. The lower end of the sheath 57 is sealed welded to the secondary sealing membrane 14. Thus, a space primary 58 is provided between the sheath 57 and the inner barrel 29. An annular passage is provided between the inner barrel 29 and the sheath 57, which allows a fluid present in the primary thermally insulating barrier 15 to circulate towards the primary space 58 or vice versa.

[0064] The dome structure 25 comprises an exhaust duct 59 which opens into the interior of the primary space 58. The exhaust duct 59 is connected to a valve, not illustrated, which, by default, is closed and which opens when the pressure in the primary thermally insulating barrier 15 exceeds a predetermined threshold pressure. The exhaust duct 59 is thus intended to protect the primary sealing membrane 17 against overpressures likely to occur in the primary thermally insulating barrier 15. Advantageously, the exhaust duct 59 comprises a helical zone winding around the inner barrel 29 and thus allowing thermal contractions and expansions of said exhaust duct 59.

[0065] The dome structure 25 also comprises an inerting conduit 60 which also opens into the interior of the primary space 58. The inerting conduit 60 is connected to a reservoir and / or to a generator of inert gas, such as nitrogen, by a compressor, which makes it possible to circulate inert gas in the primary thermally insulating barrier 15.

[0066] Furthermore, the sheath 57 is not welded to the inner shell 18 of the double shell so that the opening 27 has, between said sheath 57 and the inner shell 18, an annular passage portion allowing the fluid present in the secondary thermally insulating barrier 12 to circulate towards the secondary space 52. A secondary exhaust duct 61 and an inerting duct 62 pass through the outer barrel 26 in a sealed manner to open into the secondary space 52. The secondary exhaust duct 61 is connected to a valve which, by default, is closed and which opens when the pressure inside the secondary thermally insulating barrier 12 exceeds a predetermined threshold. It thus makes it possible to protect the secondary sealing membrane 14 against excess pressures likely to occur in the secondary thermally insulating barrier 12.The inerting conduit 62 is connected to a reservoir and / or a generator of inert gas, such as nitrogen, by a compressor, which makes it possible to circulate the inert gas in the secondary thermally insulating barrier 12.

[0067] In the embodiment, the secondary thermally insulating barrier 12 comprises one or more elements made of porous materials 36, arranged all around the sheath 57, opposite the annular passage part provided between the sheath 57 and the internal shell 18. The element or elements made of porous materials 36 are made of a material chosen from glass wool, rock wool and polyester wadding and are, preferably made of glass wool. The presence of such elements made of porous material 36 opposite the annular passage part provided between the sheath 57 and the internal shell 18 aims to facilitate the circulation of gas from the secondary thermally insulating barrier 12 to the secondary space 52. However, such materials have the disadvantage of absorbing humidity, which can lead to the formation of ice capable of blocking the aforementioned circulation of gas.

[0068] Also, as shown in [Fig. 4], the annular portion 34 of the inner shell 18 which borders the opening 27 comprises a plurality of lights 38 which are distributed around the opening 27. The lights 38 are through-holes, that is to say they pass through the inner shell 18 and thus allow the gas present in the secondary thermally insulating barrier 12 to circulate towards the secondary space 52 of the dome structure 25. The secondary insulating panels 20 of the secondary thermally insulating barrier 12 rest against the inner shell 18 by means of a plurality of mastic beads 39. Such mastic beads 39 make it possible in particular to compensate for the flatness defects of the inner shell 18. They also have the effect of creating interstices between the secondary insulating panels 20 and the inner shell 18 which promote the passage of gas.

[0069] According to an advantageous embodiment, as shown in particular in [Fig. 6], the wedge 56 interposed between said support collar 54 and said annular flange 55 also has slots 49. Such slots 49 thus facilitate the passage of gas through the lower anchoring device 32. Alternatively, the wedge 56 is composed of several pieces with a spacing between them allowing the passage of gas through the lower anchoring device 32. It can also be seen in [Fig. 6] that the frustoconical support element 53 has holes 47, 48 which also allow the circulation of gas through the lower anchoring device 32 and are respectively crossed by the exhaust duct 59 and the inerting duct 60.

[0070] In relation to [Fig. 5], the structure of an insulating lining 40 which is housed in the sheath 57 according to an advantageous embodiment is described below. In this embodiment, the insulating lining 40 is annular in shape. It comprises two sectors of polymer foam 41, 42 and two sectors of porous material 43, 44. The two sectors of polymer foam 41, 42 each comprise a through-orifice 45, 46 which passes through said sector of polymer foam 41, 42 in the direction of thickness of the ceiling wall. As shown in [Fig.4], the through-orifice 45 is connected to the exhaust duct 59 while the through-orifice 46 is connected to the inerting duct 60. Thus, the gas circulates through the through-orifices 45, 46 between the primary thermally insulating barrier 15 and the exhaust duct 59 or the inerting duct 60, which prevents the circulation of gas from either blocked by ice as it can be through a porous material.

[0071] Furthermore, the two porous material sectors 43, 44 are respectively positioned in one and the other of the two spaces provided between the two polymer foam sectors 41, 42. When they are housed inside the sheath 57, the two porous material sectors 43, 44 are each force-fitted between the two polymer foam sectors 41, 42. In other words, they are arranged in a compressed state in which they are able to relax to compensate for the thermal contraction of the polymer foam sectors 41, 42.

[0072] The porous material sectors 43, 44 are made of a material chosen from glass wool, rock wool and polyester wadding, the preferred material being glass wool.

[0073] In the embodiment shown, the primary thermally insulating barrier 15 comprises one or more elements made of porous materials 37, arranged all around the inner barrel 29, opposite the annular passage which is provided between the inner barrel 29 and the sheath 57.

[0074] With reference to [Fig. 7], a cutaway view of an LNG carrier 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 LNG 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.

[0075] 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 LNG from or to the tank 71.

[0076] [Fig. 7] 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 LNG carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 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. loading 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 LNG carrier 70 at a great distance from the coast during loading and unloading operations.

[0077] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the onshore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0078] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0079] 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.

[0080] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. Installation for storing a liquefied gas comprising: a supporting structure (1); a sealed and thermally insulating tank, intended to store a liquefied gas, comprising an upper wall successively having in a thickness direction, at least one secondary thermally insulating barrier (12) resting against the supporting structure (1) and a secondary sealing membrane (14) resting against the secondary thermally insulating barrier (12);and a dome structure (25) comprising: - an inner barrel (29) passing through an opening (27) provided in the supporting structure (1) and passing through the upper wall of the tank - an outer barrel (26) arranged around the barrel (29) and providing a secondary space (52) radially between the inner barrel (29) and the outer barrel (26), said secondary space (52) communicating with the secondary thermally insulating barrier (12) by an annular passage portion which is provided, in the opening (27), radially outside the inner barrel (29), the outer barrel (26) being fixed to the supporting structure (1) around an annular portion (34) of the supporting structure (1) which borders said annular passage portion; and - a secondary exhaust device intended to evacuate a fluid from the secondary thermally insulating barrier (12) comprising a secondary exhaust duct (61) opening into the secondary space (52);said storage installation being characterized in that the annular portion (34) of the supporting structure (1) comprises a plurality of through-holes (38) which are distributed around the annular passage portion and allow circulation of gas from the secondary thermally insulating barrier (12) to the secondary space (52).;

2. A liquefied gas storage facility according to claim 1, wherein the secondary thermally insulating barrier (12) comprises one or more elements made of porous materials (36), arranged outside the inner barrel (29) opposite the annular passage portion.

3. A liquefied gas storage facility according to claim 1 or 2, wherein the outer barrel (26) and the inner barrel (29) are anchored to each other by an upper anchoring device (31) and a device lower anchoring device (32), and in which the secondary exhaust duct (61) opens into the secondary space (52) between the upper anchoring device (31) and the lower anchoring device (32), the lower anchoring device (32) being equipped with passages (47, 48, 49) allowing gas to circulate through said lower anchoring device (32).

4. A liquefied gas storage facility according to claim 3, wherein the lower anchoring device (32) comprises a frustoconical support element (53) which flares downwards and is fixed to the inner barrel (29), a support collar (54) which is fixed to the frustoconical support element (53) and projects radially outwards and an annular flange (55) which is fixed to the outer barrel (26) and projects radially inwards of said outer barrel (26), the support collar being supported by the annular flange.

5. A liquefied gas storage facility according to claim 4, wherein the frustoconical support element (53) has holes (47, 48).

6. A liquefied gas storage facility according to claim 4 or 5, wherein a shim (56) is interposed between the support collar (54) and the annular flange (55), the shim (56) having slots (49) allowing the circulation of gas through said lower anchoring device (32).

7. A liquefied gas storage facility according to claim 4 or 5, wherein a shim (56) is interposed between the support collar (54) and the annular flange (55), the shim (56) consisting of several pieces with a spacing between them allowing the circulation of gas through said lower anchoring device (32).

8. A liquefied gas storage facility according to any one of claims 1 to 7, wherein the upper wall has a primary thermally insulating barrier (15) resting against the secondary sealing membrane (14) and a primary sealing membrane (17) resting against the primary thermally insulating barrier (15) and intended to be in contact with the liquefied gas stored in the tank and in which the inner drum (29) is welded in a sealed manner to the primary sealing membrane (17).

9. Installation for storing a liquefied gas according to claim 8, comprising: - a sheath (57) which is arranged around the inner barrel (29), said sheath (57) comprising a lower end which is connected in a sealed manner to the secondary sealing membrane (14); said sheath (57) being connected in a sealed manner to the inner barrel (29) so as to provide a primary space (58) between the sheath (57) and the inner barrel (29); said primary space (58) communicating with the primary thermally insulating barrier (15); and - a primary exhaust duct (59) and a primary inerting duct (60) which open into the primary space (58).

10. A liquefied gas storage facility according to claim 9, wherein an insulating lining (40) is housed in the sheath (57), said insulating lining (40) having an annular shape and comprising: - at least two polymer foam sectors (41, 42) each comprising a through-orifice connected to the primary exhaust duct (59) and to the primary inerting duct (60); and - at least one porous material sector (43, 44) force-fitted in each space provided between two adjacent polymer foam sectors (41, 42).

11. A liquefied gas storage facility according to claim 10, wherein the polymer foam sectors (41, 42) are made of polyurethane foam.

12. A liquefied gas storage facility according to claim 10 or 11, wherein the porous material sectors (43, 44) are made from a material chosen from glass wool, rock wool and polyester wadding.

13. A vessel (70) for transporting a liquefied gas, the vessel comprising a liquefied gas storage facility according to any one of claims 1 to 12.

14. A transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 13, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) of the liquefied gas storage facility of the vessel to a floating or land-based storage facility (77) and 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 tank of the liquefied gas storage facility of the vessel.

15. A method of loading or unloading a ship (70) according to claim 13, wherein a liquefied gas is conveyed through insulated pipes (73, 79, 76, 81) from or to a loading installation. floating or land-based storage (77) to or from the tank (71) of the ship's liquefied gas storage facility.

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