Facility for storing liquefied gas including dome structure

Abstract

To provide a dome structure penetrating through a ceiling wall of a liquefied natural gas storage tank in which gas present in a secondary heat insulation barrier is circulated in a secondary space of the dome structure.SOLUTION: A liquefied gas storage facility includes a load bearing structure, a closed heat insulation tank and a dome structure. In the liquefied gas storage facility, the dome structure includes: an inner drum passing through an opening (27) formed in the load bearing structure; an outer drum (26) disposed around the inner drum and fixed to the load bearing structure around an annular part (34) of the load bearing structure; and a secondary discharge duct that appears in a secondary space. The annular part (34) of the load bearing structure includes a plurality of through holes (38) distributed around an annular passage part and allowing circulation of gas from a secondary heat insulation barrier to the secondary space.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to the field of installations for the storage and / or transportation of liquefied gases, such as installations for transporting liquefied petroleum gas (also called LPG) having a temperature lying in the range between -50°C and 0°C, or liquefied natural gas (LNG) at atmospheric pressure, which has a temperature of about -162°C.

[0002] These installations may be located on land or on floating structures, in which case they may be intended for the transport of liquefied gas or for the reception of liquefied gas to serve as fuel for the propulsion of the floating structure.

[0003] The invention relates more particularly to an installation of the above-mentioned type comprising a tank and a dome structure passing through the ceiling wall of said tank. [Background technology]

[0004] WO 2019 / 030447 discloses a dome structure penetrating the ceiling wall of a liquefied natural gas storage tank. The dome structure defines a passage between the interior space of the tank and a vapor collector arranged outside the tank. The dome structure includes an inner drum penetrating the double hull and the ceiling wall of the tank and firmly welded to the primary sealing membrane of the ceiling wall. An outer drum arranged around the inner drum is fixed to the inner shell of the double hull. The dome structure also includes a sheath arranged radially between the outer drum and the inner drum and firmly connected to the secondary sealing membrane. A primary space is formed between the sheath and the inner drum, which communicates with the primary insulating barrier. A primary exhaust device is connected to the primary space and can vent gas from the primary insulating barrier of the tank and can protect the primary sealing membrane from overpressure. The dome structure also includes a primary inerting duct emerging in the primary space. A thermal insulating packing made of polymer foam is housed in the primary space around the entire circumference of the sheath. The insulating packing has a through passageway to allow connection between the duct of the primary exhaust system and the primary insulating barrier.

[0005] The inner shell has an annular passage around the sheath for circulating gas present in the secondary insulating barrier to a secondary space of a dome structure formed radially inside the outer drum. A secondary exhaust is coupled to the secondary space and can vent gas from the secondary insulating barrier and protect the secondary sealing membrane from overpressure. The dome structure also includes a secondary inert duct emerging into the secondary space. Facing the annular passage, the secondary insulating barrier includes glass wool around the entire circumference of the sheath.

[0006] Such a dome structure is not entirely satisfactory. In fact, the inventors have discovered that when an inert gas containing a small amount of moisture penetrates the secondary insulation barrier, the moisture contained therein is likely to be absorbed by the glass wool arranged around the entire exterior and solidify in the form of ice. In such a situation, the ice will impede the circulation of the gas through the glass wool, thereby affecting the evacuation of the gas from the secondary insulation barrier.

[0007] In addition, when the tank is cooled, the polymer foam insulating packing arranged in the primary space shrinks and creates gaps, which affects the insulating performance of the primary space. Summary of the Invention

[0008] One idea underlying the present invention is to propose an installation for the storage of liquefied gas comprising a dome structure of the above-mentioned type, equipped with a secondary exhaust device making it possible to reliably evacuate the gas from the secondary insulating barrier.

[0009] According to one aspect, the present invention provides a liquefied gas storage facility, comprising a load-bearing structure, a sealed insulated tank for storing liquefied gas, the tank including a load-bearing structure, a top wall having a secondary insulating barrier that is continuous in the thickness direction and that rests against the load-bearing structure, and a secondary sealing membrane that rests against the secondary insulating barrier, and a dome structure that passes through an opening formed in the load-bearing structure and through the top wall of the tank, and an outer drum that is arranged around the inner drum and that forms a secondary space between the inner drum and the outer drum in the radial direction. The secondary space is connected to the secondary insulation barrier by an annular passage formed in the opening and located radially outside of the inner drum, the outer drum including an outer drum fixed to the load-bearing structure around an annular portion of the load-bearing structure that defines the boundary of the annular passage, and a secondary exhaust device having a secondary exhaust duct emerging in the secondary space and for exhausting fluid from the secondary insulation barrier, the annular portion of the load-bearing structure having a plurality of through openings distributed around the annular passage and allowing circulation of gas from the secondary insulation barrier to the secondary space.

[0010] Such through openings therefore provide an additional path for gas to circulate from the secondary insulating barrier to the secondary space, so that even if ice forms on the porous material facing the annular passage and blocks gas flow through the annular passage of the opening, sufficient gas circulation is still possible from the secondary insulating barrier to the secondary space.

[0011] According to a second aspect, which may be implemented independently from the first aspect described above, the present invention also provides a liquefied gas storage facility, comprising a load-bearing structure, a top wall having a thickness direction and at least a secondary insulating barrier resting against the load-bearing structure, a secondary sealing membrane resting against the secondary insulating barrier, a primary insulating barrier resting against the secondary sealing membrane, and a primary sealing membrane resting against the primary insulating barrier, a sealed insulated tank for storing liquefied gas, and a dome structure passing through an opening formed in the load-bearing structure, passing through the top wall of the tank and securely welded to the primary sealing membrane, and a dome structure arranged around the inner drum and extending around the opening formed in the load-bearing structure. the sheath being fixed to the load-bearing structure by a secondary sealing membrane; a sheath disposed around the inner drum and having a lower end firmly connected to the secondary sealing membrane, the sheath being firmly connected to the inner drum so as to form a primary space between the sheath and the inner drum, the primary space being connected to the primary insulation barrier; a primary exhaust duct and a primary inert duct emerging in the primary space; and a thermal insulation packing housed within the sheath and having an annular shape, the packing comprising at least two segments made of polymer foam, each having a through hole connected to the primary exhaust duct and the primary inert duct, and at least one segment made of a porous material pressed into a space between each of the two adjacent segments made of polymer foam.

[0012] According to several embodiments, in relation to the first or second aspect, such a liquefied gas storage facility may comprise one or more of the following features:

[0013] According to one embodiment, the secondary exhaust duct passes through the outer drum.

[0014] According to one embodiment, the secondary exhaust duct is connected to a valve that is closed by default and opens when the pressure in the primary insulating barrier exceeds a predetermined threshold pressure.

[0015] According to one embodiment, the dome structure comprises a secondary inert duct emerging into the secondary space.

[0016] According to one embodiment, the secondary inert duct passes through the outer drum.

[0017] According to one embodiment, the secondary inert duct is connected to a reservoir and / or generator of an inert gas, such as nitrogen, by a compressor.

[0018] According to one embodiment, the secondary insulation barrier comprises a secondary insulation panel that abuts against the load-bearing structure via a plurality of mastic beads that define a gap between the secondary insulation panel and the load-bearing structure, which further facilitates the escape of gases through the through opening.

[0019] According to one embodiment, the secondary insulating barrier comprises one or more elements made of a porous material arranged on the outside of the inner drum and facing the annular passage portion, which promotes the circulation of gas from the secondary insulating barrier to the secondary space and prevents ice formation in the elements made of the porous material.

[0020] According to one embodiment, the outer drum and the inner drum are fixed to each other by an upper fixture and a lower fixture, the exhaust duct emerges in a secondary space between the upper fixture and the lower fixture, the lower fixture being provided with a passage allowing the circulation of gas through said bottom fixture.

[0021] According to one embodiment, the bottom fixing device comprises a tapered support element extending downwards and fixed to the inner drum, a radially outwardly projecting support collar fixed to the tapered support element, and a radially outwardly projecting annular flange fixed to the outer drum, the inner side of which the support collar is supported by the annular flange.

[0022] According to one embodiment, the tapered support element has a hole.

[0023] According to one embodiment, at least two holes formed in the tapered support element are passed by a primary exhaust duct and a primary inert duct, respectively, emerging in the primary space connecting with the primary insulating barrier.

[0024] According to one embodiment, a filler block is inserted between the support collar and the annular flange.

[0025] According to one embodiment, the filler block has slits to allow for circulation of gas through the bottom fixture.

[0026] According to another embodiment, the filler block interposed between the support collar and the annular flange is made of multiple pieces having gaps therebetween to allow for the circulation of gas through the bottom fastener.

[0027] According to one embodiment, the upper wall has a primary insulating barrier abutting a secondary sealing membrane and a primary sealing membrane abutting the primary insulating barrier and intended to be in contact with the liquefied gas stored in the tank.

[0028] According to one embodiment, the inner drum is securely welded to the primary sealing membrane.

[0029] According to one embodiment, the liquefied gas storage facility comprises a sheath disposed around the inner drum, the sheath having a lower end that is firmly connected to a secondary sealing membrane, the sheath being firmly connected to the inner drum to form a primary space between the sheath and the inner drum, the primary space connecting with a primary insulating barrier, and a primary exhaust duct and a primary inert duct emerging within the primary space.

[0030] According to one embodiment, the primary exhaust duct is connected to a valve that is closed by default and opens when the pressure within the primary insulating barrier exceeds a predetermined threshold pressure.

[0031] According to one embodiment, the primary inert duct is connected to a reservoir and / or generator of an inert gas, such as nitrogen, by a compressor.

[0032] According to one embodiment, the insulating packing is housed in the sheath, said insulating packing having an annular shape and at least two segments made of polymer foam, each segment having a through orifice connected to the primary exhaust duct and the primary inert duct, and at least one segment made of a porous material is pressed into each space formed between two adjacent segments made of polymer foam.

[0033] Such a structure is advantageous in that the orifices formed in the two segments made of polymer foam are not easily blocked by ice as are the pores in the porous material, so that gas can circulate reliably between the primary insulation barrier and the primary inert and exhaust ducts. Furthermore, by mounting the corner segments made of porous material in a compressed state, the thermal contraction of the corner segments made of polymer foam can be compensated for, resulting in excellent insulation performance.

[0034] According to one embodiment, the polymer foam segments are made from polyurethane foam.

[0035] According to one embodiment, the segment made of porous material is manufactured from a material selected from the group consisting of glass wool, rock wool and polyester cotton.

[0036] Such installations may form part of an onshore storage facility, for example for storing LNG, or may be installed on floating, coastal or deep-sea structures, in particular methane tanker vessels, Floating Storage and Regasification Units (FSRUs), Remote Floating Production Storage Units (FPSOs), etc. Such tanks also serve as fuel storage for ships of all kinds.

[0037] According to one embodiment, a vessel for transporting liquefied gas comprises a liquefied gas storage facility of the type described above.

[0038] According to one embodiment, the present invention also provides a liquefied gas transfer system comprising a vessel as described above, an insulated pipeline arranged to connect the tanks of the liquefied gas storage facility of the vessel to a floating or on-shore storage facility, and a pump for driving a flow of liquefied gas through the insulated pipeline from the floating or on-shore storage facility to the tanks of the liquefied gas storage facility of the vessel or from the tanks of the liquefied gas storage facility of the vessel to the floating or on-shore storage facility.

[0039] According to one embodiment, the invention also provides a method for loading or unloading such a vessel, in which liquefied gas is transported through an insulated pipeline from a floating or on-shore storage facility to the tanks of the liquefied gas storage facility of the vessel, or from the tanks of the liquefied gas storage facility of the vessel to the floating or on-shore storage facility.

[0040] The present invention, as well as other objects, details, features and advantages thereof, will become more apparent in the following description of specific embodiments of the invention, taken in conjunction with the following non-limiting drawings and the accompanying figures, in which: [Brief description of the drawings]

[0041] [Figure 1] FIG. 1 is a schematic perspective view of a support structure intended to support a sealed, insulated tank for storing liquefied gas, where the dome structure is not shown. [Diagram 2] FIG. 2 is a schematic diagram of the multi-layer structure of the tank wall. [Diagram 3] FIG. 3 is a cross-sectional view of a dome structure passing through the ceiling wall of a sealed, insulated tank, according to one embodiment. [Figure 4] FIG. 4 is a detailed view of the ceiling wall and dome structure of the tank in FIG. [Diagram 5] FIG. 5 is a perspective view of an insulating packing according to an advantageous embodiment, intended to be placed inside the sheath of the dome structure shown in FIGS. [Figure 6] FIG. 6 is a top view of a bottom fastening device that allows the inner drum to be fastened to the outer drum in the dome structure shown in FIGS. [Figure 7] FIG. 7 is a schematic cross-sectional view of a ship equipped with liquefied natural gas storage tanks and a terminal for loading and unloading of said tanks. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] With reference to FIG. 1, a load-bearing structure 1 is described, to which a sealed insulated tank for storing liquefied gas is fixed. The load-bearing structure 1 is formed, for example, by a 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 load-bearing structure 1 has an approximately polyhedral shape. It has two walls, front and rear, which are here octagonal, of which only the rear load-bearing wall 2 is shown in FIG. 1. The front and rear walls 2 are, for example, ship closing walls and extend transversely to the longitudinal direction of the ship. The load-bearing structure 1 also comprises an upper load-bearing wall 3, a bottom load-bearing wall 4 and lateral load-bearing walls 5, 6, 7, 8, 9, 10. The sealed, insulated tank for storing liquefied gas comprises a number of tank walls each fixed to one of the load-bearing walls 2, 3, 5, 6, 7, 8, 9, 10 of the load-bearing structure 1, thus defining an interior space for containing the liquefied gas.

[0043] As shown in Figure 2, each wall of the tank comprises, successively from the outside to the inside in the thickness direction of the wall, a secondary insulating barrier 12 comprising an insulating element 13 fixed to the load-bearing structure 1, a secondary sealing membrane 14 fixed to the insulating element 13 of the secondary insulating barrier 12, a primary insulating barrier 15 comprising an insulating element 16 fixed to the insulating element 13 of the secondary insulating barrier 12 or to the load-bearing structure 1 and leaning against the secondary sealing membrane 14, and a primary sealing membrane 17 fixed to the insulating element 16 of the primary insulating barrier 15 and intended to be in contact with the liquefied gas contained in the tank.

[0044] The liquefied gas intended to be stored in the tanks may in particular be ethane, liquefied natural gas (LNG), i.e. a gaseous mixture containing mainly methane and one or more other hydrocarbons, or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons obtained from the refining of petroleum, including essentially propane and butane.

[0045] In the embodiment shown in Figures 3 and 4, the insulating element of the secondary insulating barrier 12 is a secondary insulating panel 20 comprising a layer of insulating polymer foam 21, e.g. made of polyurethane, sandwiched between a cover plate 22 and a base plate 23 which is rigid and made, e.g., of plywood.

[0046] The secondary sealing membrane 14 is formed by continuous sheet strakes with raised edges. Each strake has a flat central part resting on the cover plate of the secondary insulation panel 20 and two raised edges projecting towards the interior of the tank. The strakes are welded by their raised ends onto weld supports fixed in grooves formed on the cover plate 22 of the secondary insulation panel 20. The strakes are made, for example, of Invar®, an alloy of iron and nickel, the coefficient of expansion of which is typically 1.2×10 -6 K -1 From 2.0×10 -6 K -1 It is also possible to use alloys of iron and manganese, whose expansion coefficients are typically between 7×10 -6 K -1 From 10×10 -6 K -1 That is the extent of it.

[0047] The insulating element of the primary insulating barrier 15 is a primary insulating panel 24 comprising a layer of insulating polymer foam, for example made of polyurethane, sandwiched between rigid cover and base plates, for example made of plywood.

[0048] The primary sealing membrane 17 is obtained by assembling several corrugated metal sheets by lap welding along their edges. The corrugations protrude towards the interior of the tank. The corrugated metal sheets are fixed on anchor strips fixed in countersunk holes formed in the cover plate of the primary insulation panel 24. The corrugated metal sheets are made, for example, of stainless steel or aluminium.

[0049] Alternatively, the tank walls may be manufactured according to the techniques described in WO 14 / 057221, FR 2 691 520 and FR 2 877 638, which respectively cover products such as Mark V, Mark III® and NO96® developed by the Applicant.

[0050] With reference to Figures 3 and 4, the dome structure 25 according to one embodiment will be described as follows. The dome structure 25 comprises a cylindrical outer drum 26 extending in the thickness direction of the tank's roof wall. The outer drum 26 passes through an opening formed in the outer shell 19. The lower end of the outer drum 26 is firmly welded to the inner shell 18 around an opening 27 formed in the inner shell 18. The inner shell 18 thus comprises an annular portion 34 adjacent to the opening 27 and disposed radially inward of the outer drum 26.

[0051] The upper structure of the outer drum 26 is tightly closed by a removable cover 28 .

[0052] The dome structure 25 also comprises an inner drum 29 disposed inside the outer drum 26. The inner drum 29 is concentric with the outer drum 26 and passes through an opening 27 formed in the inner shell 18. The inner drum 29 also passes through the upper wall of the tank. The inner drum 29 comprises a bottom end which is firmly welded to the primary sealing membrane 17 to ensure the sealing of the primary insulating barrier 15 to the interior space of the tank. The inner drum 29 is open at both ends thereof. The outer drum 26 and the inner drum 29 are fixed to each other by an upper fixing device 31 and a lower fixing device 32.

[0053] The upper fastening device 31 comprises a support collar 50 fixed to the inner drum 29 and projecting radially outward around the inner drum 29, and an annular flange 51 welded to the outer drum 26 and projecting radially towards the inside thereof. The support collar 50 rests against the annular flange 51. The support collar 50 and the annular flange 51 are firmly welded to one another. A secondary space 52 is thus formed below said support collar 50 and the annular flange 51 between the outer drum 26 and the inner drum 29. Below the upper fastening device 31, a layer of thermal insulation 65 is distributed evenly over the outer extent of the inner drum 29.

[0054] In the embodiment shown, the inner drum 29 is fixed to the support collar 50 via a compensation device, visible in Figure 3, which allows the inner drum 29 to contract or expand. The compensation device here comprises a metal tube having a number of bellows fixed to the inner drum 29 on the one hand and to the support collar 50 on the other hand.

[0055] The bottom fastening device 32 comprises a tapered support element 53 which extends downwards and is welded to the inner drum 29 around the latter. The bottom fastening device 32 also comprises a support ring which is welded to the radially outer edge of the tapered support element 53 and which comprises a support collar 54 which projects radially outwards. The bottom fastening device 32 also comprises an annular flange 55 which is welded to the outer drum 26 and which projects radially towards its inside. The support collar 54 rests on the annular flange 55 directly or indirectly, as shown in the illustrated embodiment, via a filler block 56 which is interposed between said support collar 54 and said annular flange 55. The filler block 56 is, for example, made of wood. It is fixed relative to the support collar 54 and the annular flange 55, for example by bolting and / or gluing by means of resin or glue. Advantageously, the thickness of the filler block 56 is determined so as to accommodate the manufacturing and / or positioning tolerances of the inner drum 29 relative to the outer drum 26 in the thickness direction of the tank's roof wall.

[0056] The dome structure 25 also comprises a duct 33, concentric with and penetrating the inner drum 29. This duct 33 in particular makes it possible to direct the vapor phase of the liquefied gas stored in the tank from the tank's interior space to a collection zone 35 located at the upper end of the dome structure 25. The dome structure 25 also comprises at least one vapor collection duct 63, which passes tightly through the wall of the outer drum 26 and emerges in the collection zone 35. The vapor collection duct or ducts 63 can thus direct vapor between the collection zone 35 and a vapor collector, not shown, which is arranged outside the dome structure 25.

[0057] The dome structure 25 also comprises a sheath 57, seen in Figures 3 and 4, which is concentric with the outer drum 26 and is disposed radially between the outer drum 26 and the inner drum 29. The sheath 57 also passes through the opening 27 formed in the inner shell 18. The upper end of the sheath 57 is securely welded to the upper annular plate 30, which is also securely welded to the inner drum 29. The lower end of the sheath 57 is securely welded to the secondary sealing membrane 14. Thus, a primary space 58 is formed between the sheath 57 and the inner drum 29. An annular passage is formed between the inner drum 29 and the sheath 57, which allows the fluid present in the primary insulating barrier 15 to pass and circulate towards the primary space 58, or vice versa.

[0058] The dome structure 25 comprises an exhaust duct 59 emerging in the primary space 58. The exhaust duct 59 is by default closed and is connected to a valve, not shown, which opens when the pressure in the primary insulating barrier 15 exceeds a given threshold value. The exhaust duct 59 is thus intended to protect the primary sealing membrane 17 from overpressure that may emerge in the primary insulating barrier 15. Advantageously, the exhaust duct 59 comprises a spiral zone that wraps around the inner drum 29, thus allowing thermal contraction and expansion of said exhaust duct 59.

[0059] The dome structure 25 also comprises an inert duct 60 which also appears inside the primary space 58. The inert duct 60 is connected by a compressor to a reservoir and / or generator of an inert gas, such as nitrogen, and allows for the circulation of the inert gas within the primary insulating barrier 15.

[0060] Furthermore, since the sheath 57 is not welded to the inner shell 18 of the double hull, the opening 27 has an annular passage between said sheath 57 and the inner shell 18, allowing the fluid present in the secondary insulating barrier 12 to circulate towards the secondary space 52. The secondary exhaust duct 61 and the inert duct 62 pass tightly through the outer drum 26 and emerge into the secondary space 52. The secondary exhaust duct 61 is closed by default and is connected to a valve that opens when the pressure in the secondary insulating barrier 12 exceeds a certain threshold value. It is thus possible to protect the secondary sealing membrane 14 from overpressure that may appear in the secondary insulating barrier 12. The inert duct 62 is connected by a compressor to a reservoir and / or generator of an inert gas, such as nitrogen, and allows the inert gas to circulate in the secondary insulating barrier 12.

[0061] In this embodiment, the secondary insulating barrier 12 comprises one or more elements of porous material 36 arranged around the entire circumference of the sheath 57 facing the annular passage formed between the sheath 57 and the inner shell 18. The elements made of porous material 36 are made of one material selected from glass wool, rock wool and polyester padding, preferably made of glass wool. The purpose of the presence of such elements of porous material 36 facing the annular passage formed between the sheath 57 and the inner shell 18 is to facilitate the circulation of gas from the secondary insulating barrier 12 to the secondary space 52. On the other hand, such materials have the disadvantage of absorbing moisture, which can lead to the formation of ice and thus impede the circulation of said gas.

[0062] Also, as shown in FIG. 4, the annular portion 34 of the inner shell 18 adjacent to the opening 27 comprises a number of openings 38 distributed around the opening 27. The openings 38 are through openings, i.e. they pass through the inner shell 18 and thus allow the gas present in the secondary insulating barrier 12 to circulate towards the secondary space 52 of the dome structure 25. The secondary insulating panel 20 of the secondary insulating barrier 12 rests against the inner shell 18 via a number of mastic beads 39. In particular, these mastic beads 39 make it possible to neutralize the flatness defects of the inner shell 18. They also have the effect of forming gaps between the secondary insulating panel 20 and the inner shell 18 that facilitate the passage of gas.

[0063] According to one advantageous embodiment, as shown in particular in Fig. 6, the filler block 56 interposed between said support collar 54 and said annular flange 55 also has slits 49. Such slits 49 therefore facilitate the passage of gas through the bottom fastener 32. Alternatively, the filler block 56 is made up of several parts with a spacing that allows the passage of gas through the bottom fastener 32. Also in Fig. 6, the tapered support element 53 has holes 47, 48 that allow the circulation of gas through the bottom fastener 32 and through which an exhaust duct 59 and an inert duct 60 pass, respectively.

[0064] With reference to FIG. 5, the structure of the insulating packing 40 housed in the sheath 57 according to an advantageous embodiment is described below. In this embodiment, the insulating packing 40 is annular. It comprises two segments 41, 42 made of polymer foam and two segments 43, 44 made of porous material. The two segments 41, 42 made of polymer foam each comprise a through orifice 45, 46 passing through the segments 41, 42 made of polymer foam in the thickness direction 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 inert duct 60. Thus, gas circulates between the primary insulating barrier 15 and the exhaust duct 59 or the inert duct 60 through the through orifices 45, 46, thereby avoiding the gas circulation being blocked by ice, as it would be through a porous material.

[0065] Moreover, the two segments 43, 44 made of the porous material are disposed in one and the other of two spaces formed between the two segments 41, 42 made of the polymer foam, respectively. When they are housed in the sheath 57, the two segments 43, 44 made of the porous material are press-fitted between the two segments 41, 42 made of the polymer foam, respectively. In other words, they are disposed in a compressed state in which they can expand to compensate for the thermal contraction of the segments made of the polymer foam 41, 42.

[0066] The porous material segments 43, 44 are made of one material selected from glass wool, rock wool, and polyester cotton, with the preferred material being glass wool.

[0067] In the embodiment shown, the primary insulating barrier 15 comprises one or more elements made of porous material 37 arranged around the entire circumference of the inner drum 29 facing the annular passage formed between the inner drum 29 and the sheath 57.

[0068] Referring to Figure 7, a cross-section of a methane tanker vessel 70 shows a generally prismatic sealed insulated tank 71 mounted on the vessel's double hull 72. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the LNG contained within the tank, a secondary sealing membrane arranged between the primary sealing membrane and the vessel's double hull 72, and two insulating barriers arranged respectively between the primary and secondary sealing membranes and between the secondary sealing membrane and the double hull 72.

[0069] As is known per se, a loading / unloading pipeline 73 located on the top deck of the vessel can be coupled by suitable connectors to an offshore or port terminal to transfer a cargo of LNG to and from the tanks 71.

[0070] FIG. 7 shows an example of a marine terminal including a loading and unloading station 75, an underwater duct 76 and an onshore facility 77. The loading and unloading station 75 is a fixed offshore installation including a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 carries a bundle of insulated flexible tubes 79 that can be connected to a loading / unloading pipe 73. The steerable movable arm 74 fits any methane tanker style. A connecting duct, not shown, extends into the tower 78. The loading and unloading station 75 allows both unloading of methane tankers 70 to the onshore facility 77 and loading of methane tankers 70 from the onshore facility 77. The onshore facility 77 has a liquefied gas storage tank 80 and a connecting duct 81 connected to the loading and unloading station 75 via the underwater duct 76. The underwater ducts 76 allow liquefied gas to be transported over long distances, e.g. 5 km, between the loading and unloading station 75 and the onshore facility 77, thereby allowing the methane tanker vessel 70 to remain far from shore during loading and unloading.

[0071] Pumps on board the vessel 70 and / or pumps mounted on the land facility 77 and / or pumps installed at the offloading station 75 are used to generate the necessary pressure to transfer the liquefied gas.

[0072] Although the present invention has been described with reference to some specific embodiments, it is clear that the invention is in no way limited thereto, and that all technical equivalents of the described means and combinations thereof, provided that the conditions are met, are encompassed within the scope of the present invention.

[0073] Use of the terms "comprise" or "include" and their conjugations does not exclude the presence of other elements or steps in addition to those stated in a claim.

[0074] In the claims, any reference signs placed between parentheses shall not be construed as construing as limiting the claim.

Claims

1. A load-bearing structure (1); a sealed insulated tank for storing liquefied gas, comprising a top wall having a thickness-wise continuity and at least a secondary insulating barrier (12) resting against said load-bearing structure (1) and a secondary sealing membrane (14) resting against said secondary insulating barrier (12); A dome structure (25); Equipped with The dome structure (25) is an inner drum (29) passing through an opening (27) formed in the load-bearing structure (1) and passing through the top wall of the tank; an outer drum (26) arranged around the inner drum (29) and radially defining a secondary space (52) between it and the inner drum (29), the secondary space (52) being connected to the secondary thermal barrier (12) by an annular passage formed in the opening (27) and located radially outside the inner drum (29), the outer drum (26) being fixed to the load-bearing structure (1) around an annular portion (34) of the load-bearing structure (1) defining the boundary of the annular passage; a secondary exhaust device for exhausting fluid from the secondary insulating barrier (12), the secondary exhaust duct (61) emerging into the secondary space (52); Including, The annular portion (34) of the load-bearing structure (1) has a plurality of through openings (38) distributed around the annular passage portion and allowing circulation of gas from the secondary insulating barrier (12) to the secondary space (52).

2. 2. The liquefied gas storage facility of claim 1, wherein the secondary insulating barrier (12) faces the annular passage portion, is arranged outside the inner drum (29), and includes at least one porous material element (36).

3. The outer drum (26) and the inner drum (29) are fixed to each other by an upper fixing device (31) and a lower fixing device (32), The secondary exhaust duct (61) emerges in the secondary space (52) between the upper fixing device (31) and the lower fixing device (32), 3. A liquefied gas storage facility as claimed in claim 1 or 2, wherein the lower fixed device (32) is equipped with passages (47, 48, 49) allowing the circulation of gas through the lower fixed device (32).

4. The lower fixing device (32) has a tapered support element (53) which extends downward and is fixed to the inner drum (29), a support collar (54) which is fixed to the tapered support element (53) and projects radially outward, and an annular flange (55) which is fixed to the outer drum (26) and projects radially toward the inside of the outer drum (26), The liquefied gas storage facility according to claim 3, wherein the support collar (54) is supported by the annular flange (55).

5. 5. A liquefied gas storage facility as claimed in claim 4, wherein the tapered support element (53) has holes (47, 48).

6. A filler block (56) is disposed between the support collar (54) and the annular flange (56); 6. The liquefied gas storage facility according to claim 4 or 5, wherein the filler block (56) has slits (49) to allow circulation of the gas through the lower fixing device (32).

7. A filler block (56) is disposed between the support collar (54) and the annular flange (56); 6. The liquefied gas storage facility according to claim 4 or 5, wherein the filler block (56) is made up of a plurality of spaced apart components that allow circulation of the gas through the lower fixing device (32).

8. the upper wall comprises a primary insulating barrier (15) resting against the secondary sealing membrane (14) and a primary sealing membrane (17) resting against the primary insulating barrier (15) and intended to be in contact with the liquefied gas in the tank; 8. A liquefied gas storage facility as claimed in any one of claims 1 to 7, wherein the inner drum (29) is securely welded to the primary sealing membrane (17).

9. a sheath (57) disposed around the inner drum (29) and having a lower end firmly connected to the secondary sealing membrane (14), the sheath (57) being firmly connected to the inner drum (29) so as to define a primary space (58) between the sheath (57) and the inner drum (29) that connects to the primary insulating barrier (15); 9. The liquefied gas storage facility of claim 8, further comprising a primary exhaust duct (59) and a primary inert duct (60) emerging in the primary space (58).

10. A heat insulating packing (40) is housed within the sheath (57), The packing (40) has an annular shape, The packing (40) is at least two segments (41, 42) made of polymer foam, each having a through-hole connected to said primary exhaust duct (59) and said primary inert duct (60); At least one segment (43, 44) made of a porous material is pressed into the space between each of the two adjacent segments (41, 42) made of polymer foam; The liquefied gas storage facility of claim 9, comprising:

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

12. The liquefied gas storage facility according to claim 10 or 11, wherein the porous material segments (43, 44) are made of one material selected from the group consisting of glass wool, rock wool and polyester padding.

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

14. 1. A transport system for liquefied gas, comprising: The transportation system includes: A vessel (70) according to claim 13; - insulated pipes (73, 79, 76, 81) arranged to connect the tanks (71) of the liquefied gas storage facility of the ship to a floating or land-based storage facility (77); a pump for driving a flow of liquefied gas through the insulated pipe from the tanks of the liquefied gas storage facility of the vessel to the floating or onshore storage facility or from the floating or onshore storage facility to the tanks of the liquefied gas storage facility of the vessel; A transportation system comprising:

15. 14. A method of loading or unloading a ship (70) as claimed in claim 13, wherein liquefied gas is transported from the tanks (71) of the liquefied gas storage facility of the ship to a floating or land-based storage facility (77) or from the floating or land-based storage facility (77) to the tanks (71) of the liquefied gas storage facility of the ship through insulated pipes (73, 79, 76, 81).

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