JP7159301B2 - Floating structures with tanks suitable for containing liquefied combustible gases - Google Patents

Description

The present invention relates to a tank system for liquefied gas on board a ship or other floating structure.

Liquefied natural gas (LNG) primarily contains methane. The invention also relates to liquefied petroleum gas and any liquefied combustible gas.

Liquefied natural gas can be carried on board ships for transport, and such ships are called liquefied natural gas carriers. Alternatively, liquefied natural gas may be carried as fuel or at least one of fuels to power any type of vessel, such as container ships. Such ships are called LNG fueled ships, or LFS. The invention applies in particular to this second category of floating structures.

Because liquefied natural gas provides complete combustion, it is much less polluting than conventional fuels such as gasoline and diesel. Liquefied natural gas has high specific energy and high energy density because liquefaction provides high compression. Moreover, liquefied natural gas will soon become an advantageous alternative for powering ships.

However, gases have some safety constraints related to hazards related to containment and leakage risks, mainly as a result of liquefaction. These constraints provide precautions such as those recommended by the international "IGF Code" regulations issued by the International Maritime Organization, London.

As shown in FIG. 4, in a known manner the ship 10 has a first deck 11 or upper deck which is used in particular for carrying payloads C and/or cabins and living spaces for passengers. .

It is also known to arrange tanks 1 containing liquefied natural gas below the first deck 11 . As shown schematically in Figure 1, a tank 1 designed to contain a liquefied combustible gas has at least one input pipe 2 (loading or filling) and at least one output pipe 3 (withdrawal or discharge). have. These pipes 2, 3 typically link the tank 1 to a management device 7 that provides an interface with both gas suppliers and consumers/users. A typical consumer is the propulsion engine 45 of a ship. An example of a management device 7 is described in publication FR-A-3004513.

In order to isolate said tank 1, it is desirable to attach a shut-off valve 4 to each of these input pipes 2 or output pipes 3, advantageously located as close as possible to the tank 1, so that the pipes are leak free. The pipe can be closed as close as possible to the tank 1 when

The "IGF Code" regulations recommend that these isolation valves 4 be placed in a closed enclosure called the tank connection space 5 (TCS).

The "IGF Code" regulation also recommends providing a waterproof cofferdam of at least 900 mm between the tank 1 and the control device 7 . A waterproof enclosure is a substantially empty confined space that provides physical separation between zones presenting a fire hazard, such as the control device 7, and protected zones, such as the tank 1. be.

One essential idea of the present invention is to propose a structure that addresses these different regulations while facilitating installation.

To this end, a floating structure comprising a hull, at least one first deck, and an intermediate load-bearing wall located below said first deck, said floating structure containing a liquefied combustible gas. a tank designed to and arranged under said intermediate bearing wall, said tank arranged to a management device and to one or more pipes, in particular at least one filling pipe and at least one discharge pipe; at least one pipe connected to, in particular a shut-off valve arranged in each of said pipes, and said at least one said shut-off valve is encased in a sealing manner. a housing, wherein the tank is a membrane tank incorporated into the hull, the walls of the tank continuously extending from the outside to the inside of the tank, the inner surface of the hull and the intermediate load-bearing wall; and at least one sealing membrane arranged on the inner surface of said insulating layer, said tank connecting space being at least partially above said intermediate load-bearing wall. The invention proposes a floating structure, characterized in that it is arranged below the first deck at .

Such membrane tanks, unlike self-supporting tanks, feature a multi-layer structure built directly into the bearing walls provided by the ship's structure, which helps optimize the usable volume.

Depending on the embodiment, such floating structures can have one or more of the following features.

According to one embodiment, the space between the first deck and the intermediate load-bearing wall is preferably made into a waterproof enclosure around the tank connection space.

According to one embodiment, the tank connection space is supported above the intermediate load-bearing wall by one or each pipe, in particular by the filling pipe and/or the discharging pipe.

According to one embodiment, the tank connection space is supported by an intermediate load-bearing wall.

According to one embodiment, the or each pipe has a primary tube, one end of which is immersed in the tank, a secondary tube, one end of which is connected to said shut-off valve, and the other of said primary tube. The end is assembled with the other end of said secondary tube.

According to other embodiments, the primary and secondary tubes may be assembled using assembly means including flanges or sleeves or by welding the two tubes end to end.

The assembly means can be arranged inside or outside the closed enclosure. For example, the assembly means may be encased in an independent sealed housing separate from the sealed housing containing the shut-off valve. The advantage of this second sealed enclosure is to improve the protection of the ship against the risk of fire in the event of leaks from assembly means or tubes.

According to one embodiment, the ceiling wall and the intermediate load-bearing wall of the tank have wall bushings through which said at least one tube, e.g. a primary tube, passes in a sealing manner.

According to one embodiment, the wall bushing is formed in part of the intermediate load-bearing wall made of a material resistant to liquefied natural gas, preferably stainless steel.

According to another feature, the length of pipe between the wall bushing and the isolation valve is as short as possible. Preferably, the shut-off valve is positioned immediately above the intermediate load-bearing wall.

According to one embodiment, the tank connection space is arranged in a hopper formed on the first deck and, opposite the hopper, comprises sealing fixing means to the circumference of the hopper, these being the housing and the hopper. It is preferably designed to compensate for play between the ends.

According to one embodiment, said at least one fill pipe comprises a vapor phase fill pipe and a liquid phase fill pipe, and said at least one discharge pipe comprises a vapor phase discharge pipe and a liquid phase discharge pipe. , one or each gas phase pipe opens at the top of the tank and one or each liquid phase pipe opens at the bottom of the tank.

According to one embodiment, said housing is made of a material resistant to liquefied natural gas, preferably stainless steel.

According to one embodiment, the housing has an inspection hatch.

According to one embodiment, the walls of the tank are designed to contact the product contained in the tank, in order from the outside to the inside of the tank: the secondary insulation layer, the secondary sealing membrane, the primary insulation layer and the product contained in the tank. A primary sealing membrane is included.

According to one embodiment, a metal reinforcing member is fixed to the upper surface of said intermediate load-bearing wall opposite said wall of said tank. Thus, the intermediate load-bearing wall can increase stiffness and provide a normal lower surface for supporting the tank roof wall. Similarly, a metal reinforcing member can be secured to the underside of the first deck.

The metal membrane may for example have a thickness between 0.5 mm and 3 mm, preferably between 0.7 and 1.5 mm. Examples of such metal films are known, for example, from the applicant's NO96® and MarkIII® technologies.

The space between the first deck and the intermediate bearing wall can be designed somewhat compact to maximize the usable volume of the tank. For example, this space has a height of less than 1.80m, preferably less than 1.60m or less than 1.30m. Preferably, the intermediate load-bearing wall is located immediately below the first deck without being separated therefrom by another horizontal metal partition or another deck.

According to one embodiment, the intermediate load-bearing wall has a recess offset downwards with respect to the rest of the intermediate load-bearing wall, and the tank connection space is arranged flush with said recess.

These features mean that the tank connecting space, which is located flush with said recess, is in a zone where the distance between the first deck and the intermediate bearing wall is greater than the rest. The height of the space between the first deck and the intermediate bearing wall can therefore be lower, in particular less than 1 m, for example close to 0.9 m.

According to one embodiment, the invention also relates to a method of filling a ship's tank or other floating structure, as described above, wherein fluid is transferred from a land-based or floating storage facility to a ship's tank or other floating structure. Carried through insulated pipes to floating structures.

According to one embodiment, the invention also relates to a system comprising a ship or other floating structure, as described above, for transporting a ship ashore or onshore with the insulating pipes installed in the ship's hull or other floating structure. Arranged for connection to a floating storage facility, a pump drives the flow of fluid through an insulated pipe from the shore or floating storage facility to the ship's tanks or other floating structure. The hull may be a double hull including an inner hull and an outer hull.

Other desirable features of a sealed enclosure are:
- all connections of the tank and the corresponding shut-off valve are inside a sealed enclosure,
- The enclosure is airtight and reliably confines leaks from the pipes connected to the tank, in particular the sealed enclosure contains pipe connectors such as flanges,
- can provide ventilation of the enclosed enclosure to the ship's riser mast, controlled by a pressure relief valve;
- The enclosure is designed to reliably withstand the most extreme temperature conditions to which the enclosure may be exposed during operation,
- the enclosure is equipped with forced-extraction ventilation, for example with a flow rate greater than 30 times the internal volume per hour,
- the enclosure may contain a vaporization unit connected to a pipe, in particular a discharge pipe, which unit is designed to vaporize the liquefied gas stream pumped from the tank and send it to the gas consuming member; ,
- A gas compressor can be installed in the management device, preferably outside the closed enclosure, to deliver the gas to the consumer.

Other features, details and advantages of the invention are more clearly shown in the detailed description given below by way of example and in connection with the drawings.

Figure 1, already described, shows a general arrangement of various pieces of equipment of a ship in which the invention can be implemented. 1 is a schematic sectional view showing a zone of a ship above a tank in a first embodiment of the invention; FIG. FIG. 4 is a schematic cross-sectional view showing the zone of the ship above the tank in the second embodiment of the invention; 1 shows a vessel equipped with a gas storage tank and an energy generating device that propels the vessel powered by natural gas. FIG. 3 is a view similar to FIG. 2 in a modification of the first embodiment; FIG. 4 is a view similar to that of FIG. 3 in a variant of the second embodiment; FIG. 10 is a schematic perspective view of an intermediate load-bearing wall surmounted by an enclosed enclosure, according to one embodiment.

The present invention takes advantage of the presence of at least a first deck 11 or upper deck and an intermediate bearing wall 12 . By careful use of the upper deck 11 and the bearing walls 12 and primarily the space formed between them, the necessary watertight enclosure can be advantageously created.

The bearing wall 12 is preferably a steel wall provided with a reinforcing member 47 on the upper side facing the waterproof enclosure. The presence of the reinforcing member 47 on top of the bearing wall 12 allows the lower surface to be substantially flat and free of obstructions, thereby forming a closed and insulated tank wall in a multi-layer construction. can be covered.

In addition, the first deck 11 can be provided with reinforcing members 46 on the underside facing the waterproof enclosure. The presence of the reinforcing member 46 below the first deck 11 allows the upper surface to remain substantially flat and free of obstructions for movement or storage of merchandise.

Thus, a tank 1 designed to contain liquefied natural gas is arranged on a ship 10, as shown in FIGS. This tank 1 is connected to a management device 7 by at least one filling pipe 2 and at least one discharge pipe 3 . A tank connection space 5 is arranged between the tank 1 and the control device 7 . This tank connection space 5 has a shut-off valve 4 on each pipe 2,3. The tank connection space 5 also has a housing 6 sealingly enclosing said shut-off valve 4 .

The tank 1 is a membrane tank built into the hull 10 . The walls of the tank, of which only the ceiling wall 50 is shown, are, from the outside towards the inside of the tank, a secondary insulation layer 41 fixed to the inner surface of the hull 10 or intermediate bearing wall 12 and a secondary insulation layer 41 fixed to the secondary insulation layer 41. a secondary sealing membrane 42, a primary insulating layer 43 fixed to the secondary sealing membrane 42, and a primary sealing membrane 44 fixed to the primary insulating layer 43 in succession.

The tank 1 is thus arranged below the intermediate bearing wall 12 and the tank connecting space 5 is arranged above the intermediate bearing wall 12 and at least partially below the first deck 11 .

Thus, according to the embodiment shown in Figure 2, the tank connection space 5 is arranged completely below the first deck. Such a layout is one in which the management device 7 is below the first deck 11 as typically the engine 14 is also below the first deck 11 .

In a second alternative embodiment shown in FIG. 3 , the tank connection space 5 is arranged in the first deck 11 , for example in a hopper 13 formed in the first deck 11 . Such a layout makes it possible to arrange the management device 7 at least partially above the first deck 11 .

As a result, the inter-deck space between the first deck 11 and the intermediate load-bearing wall 12 forms a volume separating the tank 1 from the control device 7, which is recommended in the regulations of the "IGF Code". In addition, it is advantageously sealed to form a waterproof enclosure.

This inter-deck space may be likewise sealed, if desired, advantageously by a watertight enclosure, for example using sealed partition means. According to a preferred embodiment, a cofferdam is formed around the tank connection space 5 to secure the tank connection space 5 .

According to an advantageous feature, in order to facilitate the provision and integration of the tank system into the ship 10, each The pipes 2,3 are divided into primary tubes 21,31 and secondary tubes 22,32. The primary tubes 21,31 terminate in primary assembly means 23,33 at ends opposite ends 25,35. Similarly, secondary tubes 22 , 32 terminate in secondary assembly means 24 , 34 at ends opposite the ends connected to isolation valve 4 . The secondary assembly means 24,34 are matched for assembly with the primary assembly means 23,33. For each of the pipes 2,3, the primary assembly means 23,33 are placed together in substantial contact facing each other with the corresponding secondary assembly means 24,34.

The assembly means 23, 24, 33, 34 are any means that allow the two tubes to be assembled, usually end-to-end. Assembly means 23, 24, 33, 34 are therefore flanges or sleeves designed to be assembled in pairs, by screws, flanges or even by welding, or two tubes 21, 22, 31 , 32 to allow the pipes 2, 3 to be formed.

This feature is particularly advantageous in that it allows the tank connecting space 5 and its secondary tubes 22, 32 to be assembled with the primary tubes 21, 31 coming from the tank 1, thereby making the tank connecting space 5 Carrying out the modular assembly of the tank 1 equipped.

Assembly can be done in the following way. The tank connection space 5 is arranged near the tank 1 so that each secondary assembly means 24, 34 can face and contact the primary corresponding assembly means 23, 33. Each pipe 2, 3 is then assembled by screwing, flanging or welding. Thus, during assembly the tank connection space 5 is advantageously arranged and the secondary assembly means 24 , 34 rest on the primary assembly means 23 , 33 of the primary tubes 21 , 31 and thus on the tank 1 . This facilitates installation of the tank connection space 5 and helps reduce play between the assembly means 23, 24, 33, 34, thereby ensuring an optimal fit which is secured by subsequent assembly. .

In the assembled state the tank connection space 5 is thus supported by the secondary tubes 22,32.

Alternatively, the tank connection space 5 can be supported in a different way. For example, the tank connection space 5, more particularly its housing 6, extends into the reinforcing member 46 or 47 or into the space between the first deck 11 and the intermediate load-bearing wall 12, as indicated by the dashed lines in FIG. It can be fixed to the wall 36 . The connection between the wall 36 and the housing 6 can have one or more fixing parts 37, eg fixing lugs, as indicated using dashed lines in FIG.

The ceiling wall 50 and the intermediate bearing wall 12 of the tank 1 advantageously have wall bushings 8 to ensure that the primary tubes 21 , 31 allow the pipes 2 , 3 to connect the inside and the outside of the tank 1 . This bushing 8 allows a sealed passage of the primary tubes 21,31. An embodiment of such a bushing is described in French Patent Application No. 1653076 filed on April 7, 2016 and published under the number FR-A-3050009.

As shown, the ceiling wall 50 of the tank 1 is directly supported by the underside of the intermediate bearing wall 12 . The bushing 8 is therefore also made through the intermediate load-bearing wall 12 . According to a preferred embodiment, bushings are made in wall portions 18 blocking corresponding hoppers formed in the intermediate load-bearing wall 12 . The wall portion 18 can advantageously be pre-manufactured and/or integrated into the tank 1 during manufacture.

Wall portion 18 may come into contact with gas, especially in the case of leaks. The wall portion 18 is also preferably made of a material that is resistant to liquefied natural gas, in particular to the low temperatures that said gas can cause. According to a preferred embodiment, wall portion 18 is made of stainless steel.

The wall bushing 8 is preferably made of flat walls, as shown, which avoids the use of more cumbersome structures such as the protruding liquid domes commonly used on liquefied natural gas carriers.

The main function of the shut-off valve 4 is to make it possible to close the circuit between the leak and the tank 1 in the event of a leak in the pipes 2,3. This ensures that the length of the pipes 2, 3 between the wall portion 18 and the shut-off valve 4 is as short as possible with respect to the tube length.

With reference to the layout of FIG. 3, everything is substantially the same, except for the assembly feature of the tank connecting space in the thickness of the first deck 11 . This assembly is performed, for example, using a hopper 13 drilled into the first deck 11 substantially in the contour of the enclosure 6 of the tank connection space 5 .

As in the previous layout, preference is given to the assembly of the pipes 2,3 using the primary assembly means 23,33 and the secondary assembly means 24,34. This assembly is performed first to obtain the advantages in terms of quality and play reduction mentioned above. This assembly positions the tank connection space 5 precisely with respect to the tank 1 and thus substantially with respect to the first deck 11 . By subsequently closing the hopper 13 around the tank connection space 5 , the first deck 11 is sealed and it is possible to check the fixation of the tank connection space 5 .

Considering the aforementioned considerations, a significant relative play is advantageously provided between the hopper 13 and the tank connecting space 5 . Fixing and supporting means 51 are advantageously used. These fixing means 51 comprise, for example, a peripheral frame fixed to the tank connection space 5 facing and/or against the contour of the hopper 13 . A hermetic closure is then effected between the fixing means 51 and the first deck 11 .

Since the position of the tank connection space 5 relative to the first deck 11 is determined by the assembly of the primary tubes 21, 31 and the secondary tubes 22, 32, the fixing means 51 are advantageously designed to allow play compensation. be. This can be done using a deformable component such as a boot. This can also be done by welding, the fixing means 51 being shaped so that different volumes of weld seams can be applied as required.

According to the preferred embodiment shown in Figures 2 and 3, said at least one filling pipe, indicated generally with reference numeral 2, comprises a gas phase filling pipe 2G and a liquid phase filling pipe 2L. Similarly, said at least one discharge pipe, indicated generically with reference numeral 3, comprises a vapor phase discharge pipe 3G and a liquid phase discharge pipe 3L. The gas phase pipes 2G, 3G are advantageously open at the top of the tank 1. The liquid phase pipes 2L, 3L are advantageously open at the bottom of the tank 1.

As mentioned above, shut-off valve 4 is enclosed by housing 6 . Said housing is designed to contain the gas resulting from leakage of the shut-off valve 4 . Moreover, this housing 6 is preferably made of a material resistant to liquefied natural gas, for example stainless steel.

It must be possible to access the shut-off valve 4, operate said valve and carry out any necessary inspection or maintenance work. The enclosure 6 also advantageously includes an inspection hatch.

In an embodiment not shown, the rear wall of housing 6 is part of intermediate load-bearing wall 12 .

In the embodiment shown in FIG. 7, the rear wall of housing 6 is wall portion 18 . The reinforcing members 47 are in this case mutually perpendicular walls arranged to form a grid with a substantially square mesh projecting from the intermediate bearing wall 12 . These reinforcing members 47 are interrupted by wall sections 18 traversed by the pipes 2, 3, which wall sections are rectangular in this case. The housing 6 is in this case a cuboid whose length and width are substantially equal to the length and width of the wall portion 18, which forms the rear wall of this parallelepiped housing. The wall portion 18 can be traversed by a greater or lesser number of pipes.

5 and 6 show two embodiments in which the intermediate load-bearing wall 12 is not flat, but rather has a recess 16 that is offset downwardly with respect to the rest of the intermediate load-bearing wall 12. FIG. Elements similar or identical to those of FIGS. 2 and 3 are indicated using the same reference numerals as in FIGS.

A wall bushing 8 is formed in the recess 16 , for example in the form of a wall portion 18 . The tank connection space 5 is arranged flush with the recess 16 so that it sits in a zone 17 where the height of the space between the first deck 11 and the intermediate load-bearing wall 12 is higher than elsewhere. The zones 17 are delimited by connecting portions 15 of the intermediate load-bearing walls 12 extending on each side of the recess 16 either perpendicularly or obliquely to said wall portion as shown.

The tank connection space 5 can be fixed in various different ways, as described above. FIG. 5 shows the tank connection space 5 lying directly on the intermediate load-bearing wall 12 flush with the recess 16 . FIG. 6 shows a fixed part, eg a welded part, supporting the tank connection space 5 above the intermediate load-bearing wall 12 level with the recess 16 .

Loading/unloading pipes can be connected to sea or port terminals to transfer LNG cargo to and from tanks 1, using suitable connectors, in a known manner as shown in FIG.

FIG. 4 shows an exemplary offshore terminal with a liquefied natural gas delivery point 82, a subsea line 83 and an onshore facility 81. FIG. The liquefied natural gas delivery point 82 is a static offshore installation with a movable arm 84 and a column 85 supporting the movable arm 84 . A movable arm 84 supports an insulating hose 80 that can be connected to a load pipe. The orientable movable arm 84 can be adapted to any size vessel. A connecting line (not shown) extends inside the column 85 . Liquefied natural gas supply points 82 allow tanks of ship 10 to be filled from onshore facility 81 . The facility has a liquefied gas storage tank 86 and a connecting line 87 connected to a liquefied natural gas delivery point 82 by a subsea line 83 . Subsea line 83 allows liquefied gas to be transferred between liquefied natural gas delivery point 82 and onshore facility 81 .

Pumps onboard ship 10 and/or pumps installed at land facility 81 and/or pumps installed at loading/unloading site 82 are used to generate the pressure required to transfer the liquefied gas. .

Ports or marine terminals can also be replaced with supply vessels with LNG storage tanks to load the tanks of ship 10 .

Although the present invention has been described in connection with some particular embodiments, it is clearly in no way limited thereto and all technical equivalents of the described means and such are included within the scope of the invention. Contains a combination.

Use of the verb "comprise" or "comprise" does not exclude the presence of other elements or steps in addition to those recited in a claim, even if so used.

In the claims, any reference signs between parentheses shall not be construed as constituting a limitation on the claim.

Claims (17)

A floating structure comprising a hull (10), at least one first deck (11) and an intermediate bearing wall (12) located below said first deck (11), comprising:
The floating structure is
a tank (1) designed to contain a liquefied combustible gas and positioned below said intermediate bearing wall (12);
connecting said tank (1) to a management device (7) and a tank connection space (5) comprising at least one shut-off valve (4) arranged in one or more pipes (2, 3) at least one pipe (2, 3);
a housing (6) sealingly enclosing said at least one isolation valve (4);
The tank (1) is a membrane tank incorporated in the hull (10),
The walls of said tank are:
Continuously from the outside to the inside of the tank,
at least one thermal insulation layer supported by the inner surface of the hull and the lower surface of the intermediate bearing wall (12);
at least one sealing membrane disposed on the inner surface of the insulating layer;
said tank connection space (5) is arranged above said intermediate bearing wall (12) and at least partially below the first deck (11);
Floating structure, characterized in that the space comprising all or part of said tank connection space (5) between said first deck (11) and an intermediate bearing wall (12) is a waterproof enclosure. Floating structure according to claim 1, characterized in that said tank connection space (5) is supported above said intermediate bearing wall (12) by said at least one pipe (2, 3). Floating structure according to claim 1, characterized in that said tank connection space (5) is supported by said intermediate bearing wall (12). Floating structure according to claim 2, characterized in that the rear wall of the enclosure (6) is part (18) of the intermediate load-bearing wall (12). said at least one pipe (2, 3) comprising:
a primary tube (21, 31) with one end (25, 35) immersed in the tank (1);
a secondary tube (22, 32) one end of which is connected to the isolation valve (4);
5. A floating structure according to any preceding claim, wherein the other end of the primary tube is assembled with the other end of the secondary tube. Floating structure according to claim 5, characterized in that said primary tube is assembled with said secondary tube using assembly means (23, 24, 33, 34) comprising a flange or sleeve. Claim characterized in that the ceiling wall (50) and the intermediate load-bearing wall (12) of the tank (1) have wall bushings (8) through which the at least one pipe (2, 3) passes sealingly. Item 7. A floating structure according to any one of Items 1 to 6. Floating structure according to claim 7, characterized in that said wall bushing (8) is formed in a part (18) of said intermediate bearing wall (12) made of stainless steel. A float according to any one of the preceding claims, characterized in that a metal reinforcing member (47) is fixed to the upper surface of the intermediate load-bearing wall (12) opposite the wall of the tank. Structure. Said tank connection space (5) is located in a hopper (13) formed in said first deck (11), facing said hopper (13) and sealingly fixed around said hopper (13). Floating structure according to any one of the preceding claims, characterized in that it comprises fixing means (51) for securing. Floating structure according to claim 10, characterized in that said fixing means (51) are designed to compensate for play between said housing (6) and the end of said hopper (13). thing. said intermediate load-bearing wall (12) having a recess (16) downwardly offset with respect to the remainder of said intermediate load-bearing wall (12);
Floating structure according to any one of the preceding claims, characterized in that the tank connection space (5) is arranged at the same height as the recess (16). said at least one pipe comprises a gas phase fill pipe (2G), a liquid phase fill pipe (2L), a gas phase discharge pipe (3G) and a liquid phase discharge pipe (3L);
One or each of said gas phase filling pipe (2G) and said gas phase discharge pipe (3G) opens at the top of said tank (1), said liquid phase filling pipe (2L) and said liquid phase discharge pipe (3L) 13. Floating structure according to any one of the preceding claims, characterized in that one or each opens at the bottom of the tank (1). Floating structure according to any one of the preceding claims, characterized in that the enclosure (6) is made of a material resistant to liquefied natural gas, preferably stainless steel. 15. Floating structure according to any one of the preceding claims, characterized in that the enclosure (6) has an inspection hatch. A fluid transfer system comprising:
A floating structure according to any one of claims 1 to 15;
an insulated pipe (80) arranged to connect said tank (1) of said floating structure to a land or floating storage facility (81);
a pump for driving fluid from said land or floating storage facility to said tank (1) of said floating structure through said insulated pipe. 16. A method of filling the tank of a floating structure according to any one of claims 1 to 15, comprising:
A method, characterized in that fluid is directed from a land or floating storage facility (81) to said tank (1) of said floating structure through an insulated pipe (80).

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