Liquid dome for liquefied gas storage tank comprising an opening provided with an additional cover

Abstract

The invention relates to a storage installation (1) for liquefied gas and a sealed and thermally insulated tank (71) comprising a loading / unloading opening (10) comprising at least a first access through-hole and a second access through-hole (20, 30) having an inner end and an outer end, the outer end being fitted with a removable outer wall, the installation (1) comprising at least a first fluid-tight shell (41) surrounding the outer end of the first access hole (20), the removable outer wall of the first access hole (20) forming a wall of the first shell (41) and the first shell (41) being filled with a gas called inert gas.

Description

Technical Field

[0001] This invention relates to the field of storage devices for liquefied gases, comprising sealed and thermally insulated membrane tanks. In particular, this invention relates to the field of sealed and thermally insulated tanks for storing and / or transporting liquefied gases at cryogenic temperatures, such as tanks for transporting liquefied petroleum gas (LPG) at temperatures between -50°C and 0°C, or tanks for transporting liquefied natural gas (LNG) at atmospheric pressure at approximately -162°C. These tanks can be installed on shore or on floating structures. In the case of floating structures, the tanks can be used to transport liquefied gases or to receive liquefied gases used as fuel to propel the floating structure. Background Technology

[0002] Document FR2991430 describes a storage device for liquefied gases, comprising a sealed and thermally insulated tank integrated into a load-bearing structure consisting of a double hull of a ship. Each wall of the tank includes a secondary thermal insulation barrier, a secondary sealing membrane, a primary thermal insulation barrier, and a primary sealing membrane.

[0003] In the region located at the top of the tank, the tank has a protruding section in the form of a chimney, referred to as the liquid dome. In this region, the supporting structure is partially interrupted to define a loading / unloading opening designed to allow fluid loading / unloading conduits to pass through it. This loading / unloading opening, also known as the liquid dome, includes an insulating or thermally insulating barrier and elements forming the main sealing membrane.

[0004] However, this loading / unloading opening area lacks a secondary sealing membrane, unlike the rest of the tank which has a primary insulating membrane, followed by a secondary thermal insulation barrier, and finally the walls of the load-bearing structure. Specifically, in this region of the tank, it is assumed that the outer wall of the liquid dome itself forms the secondary sealing membrane, with the free outer surface of the liquid dome opening to the upper wall panel or even to the inner wall panel.

[0005] Following various experiments and tests, the applicant has identified weaknesses in the physical isolation (risk of leakage) and thermal insulation of the tank contents in the area of ​​the loading / unloading opening. These weaknesses could lead to adverse heat exchange conditions (as the tank's vaporization rate needs to be kept to a minimum) or leakage of the fluid contained within the tank.

[0006] The applicant overcomes these observed defects by proposing a solution that is simple, inexpensive, and, in particular, ensures a perfect physical and thermal seal for the extremely cold fluid contained in the tank. Summary of the Invention

[0007] Therefore, the present invention relates to a storage device for liquefied gases, the storage device comprising a support structure and a sealed and thermally insulated tank disposed within the support structure, the sealed and thermally insulated tank comprising a main structure formed by a plurality of tank walls interconnected and fixed to the support structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane and at least one thermally insulating barrier disposed between the sealing membrane and the support structure, the support structure comprising a generally flat upper support wall, the sealing membrane, the thermally insulating barrier, and the upper support wall of the main structure being partially interrupted to define a loading / unloading opening, the loading / unloading opening comprising at least a removable first entry through-hole and a removable second entry through-hole, the removable first entry through-hole and the removable second entry through-hole having inner ends and outer ends, the outer ends being fitted with a removable outer wall.

[0008] The invention is characterized in that the device includes at least a first fluid sealing shell surrounding the outer end of the first inlet through-hole, the removable outer wall of the first inlet through-hole forming the wall of the first shell, and the first shell being filled with a gas called an inert gas.

[0009] Therefore, after numerous tests and analyses, the applicant found that one or more access ports through the loading / unloading opening of the liquid dome were one or more weaknesses in the insulation and / or isolation of the tank or liquefied gas storage equipment. These access ports, which provide entry for people and materials respectively, are referred to by those skilled in the art as “manholes” and “material holes”.

[0010] Based on these analyses, the applicant proposes a simple, effective, and inexpensive system for completely sealing and protecting these specific areas. The shell thus forms a second sealing membrane, with the primary membrane provided by the sidewalls and outer walls of each of the two access holes.

[0011] The term "access through-hole" refers to a hole that (i.e., a manhole and material hole) passes through the inner cover of the loading / unloading opening and is formed by a cylinder, usually made of metal, having a cylindrical, rectangular, or even square cross-section.

[0012] By convention, the terms “external” and “internal” are used to refer to the interior and exterior of a container to define the relative position of one element with respect to another element.

[0013] The term "inert gas" means that it is a non-flammable gas used in the insulated space of the tank, typically molecular nitrogen (N2). This molecular nitrogen (N2) is usually mixed with residual gases from the polymer foam and adhesives used to form the thermal insulation barrier of the tank; these gases are present in small amounts compared to the amount of molecular nitrogen. Of course, all or part of this molecular nitrogen (N2) can be replaced with another non-flammable gas, preferably a gas with satisfactory thermal conductivity. Monitoring the amount of this inert gas in the insulated space of the tank, and therefore in the liquid dome, makes it particularly possible to detect the occurrence of liquefied gas or gaseous gas leaks.

[0014] Preferably, the two inlet holes, typically present in the liquid dome, are equipped with an insulating and / or isolating shell filled with an inert gas. Therefore, preferably, the device includes a second fluid-sealed shell surrounding the outer end of the second inlet hole, the removable outer wall of the second inlet hole forming the wall of the second shell, the second shell being filled with a gas called an inert gas.

[0015] Other advantageous features of the present invention are briefly described below:

[0016] Advantageously, the first shell and / or the second shell are secured by a seal welded to the outer surface of the storage device.

[0017] According to one possibility provided by the invention, the first shell and the second shell are insulated with a thermal insulation device, such as glass wool, polyurethane foam, or some other material that can be contained in the shell and has a very low thermal conductivity coefficient.

[0018] According to a preferred embodiment, the first shell and the second shell each include a removable first chamber wall and a removable second chamber wall, the dimensions of which are substantially larger than the dimensions of the removable first outer wall and the removable second outer wall of the first inlet through hole and the second inlet through hole, respectively.

[0019] According to a preferred embodiment, the removable outer walls of the first and second inlet holes, preferably together with the removable first and second chamber walls, are secured in a sealed manner using a mechanical device, such as a screw or bolt. Of course, to ensure a perfect seal, at least one seal is added to the mechanical device.

[0020] Furthermore, in a possible variation, the removable outer walls of the first and second inlet through-holes may be secured together with the removable first and second chamber walls using welding, even though this solution may prove inconvenient when disassembling these securing elements.

[0021] Therefore, the removable outer walls of the shell are respectively fixed to the corresponding two outer ends of the cylinder that constitutes the access through hole, while the removable chamber walls are respectively fixed to the fixed outer shell of each shell.

[0022] Preferably, the inner and outer walls of the first and second entry through holes are fixed to the periphery of the ends of the first and second entry through holes by mechanical means (e.g., screws or bolts) and by welding, respectively. Therefore, the removable outer walls of the first and second entry through holes are fixed in a sealed manner by mechanical means (possibly by a seal), while the inner walls of the first and second entry through holes are fixed in a sealed manner by welding.

[0023] According to a preferred embodiment, the loading / unloading opening includes a cover forming a main sealing membrane, the first entry through-hole and the second entry through-hole passing through the cover of the loading / unloading opening and being fixed to the cover in a sealing manner, preferably, the first entry through-hole and the second entry through-hole are fixed to the cover in a sealing manner by welding.

[0024] Advantageously, the first shell and / or the second shell has at least one communication channel for communication with the thermal insulation barrier of the main structure. Thus, the inert gas in one of the shells is in direct communication (preferably the same) with the inert gas in the tank's insulating space to form a single insulating space. Preferably, each shell has multiple communication channels for communication with the thermal insulation barrier of the main structure.

[0025] Advantageously, the first shell and / or the second shell are made of steel. Advantageously, this steel is stainless steel, or even...

[0026] Advantageously, the gas known as an inert gas is composed of molecular nitrogen.

[0027] Advantageously, the cover of the loading / unloading opening is directly or indirectly fixed to the main membrane of the main structure.

[0028] According to one embodiment, when the cover is directly fixed to the main membrane of the main body structure, welding is used to achieve the fixation.

[0029] According to another embodiment, when the cover is indirectly fixed to the main membrane, a fastener is used for fixing, the fastener being welded to the sealing membrane of the main structure and the cover in a sealing manner.

[0030] Advantageously, the cover comprises:

[0031] - A plurality of flat metal plates, the flat metal plates being assembled together, the flat metal plates having a coefficient of thermal expansion between 0.5 and 10. -6 By 2.10 -6 K -1 Made of an alloy of iron and nickel, or

[0032] - Multiple corrugated metal sheets, juxtaposed in a repeating pattern and welded together in a sealed manner, the sheets being made of stainless steel. It can be noted that these corrugated metal sheets may also be made of high-manganese steel; the term "stainless steel" includes this alloy.

[0033] The present invention relates to a vessel for transporting cold liquid products, the vessel having a double hull and a storage device as described above, the storage device being arranged within the double hull.

[0034] The present invention also relates to a conveying system for conveying cold liquid products, the system comprising a vessel as described above, insulated pipes, and a pump, the insulated pipes being arranged to connect tanks mounted in the hull of the vessel to a floating or land-based external storage device, and the pump being used to convey a flow of cold liquid products from the floating or land-based external storage device to the tanks of the vessel or from the tanks of the vessel to the floating or land-based external storage device via the insulated pipes.

[0035] Finally, the present invention relates to a method for loading or unloading a vessel as described above, wherein cold liquid products are supplied from a floating or land-based external storage device to the vessel's tanks or from the vessel's tanks to a floating or land-based external storage device via insulated conduits. Attached Figure Description

[0036] The invention will be better understood from the following description of several specific embodiments of the invention, provided only by way of non-limiting illustrations, and with reference to the accompanying drawings, and other objects, details, features, and advantages of the invention will become clearer.

[0037] [ Figure 1 ] Figure 1 A schematic cross-sectional view of a liquid dome according to a first embodiment of the present invention;

[0038] [ Figure 2 ] Figure 2It is a schematic cross-sectional view of a conventional manhole based on existing technology, which is equipped with a liquid dome.

[0039] [ Figure 3 ] Figure 3 The first sequence of installing a manhole in a liquid dome according to the invention is shown in cross-section.

[0040] [ Figure 4 ] Figure 4 The cross-section shows the ratio Figure 3 The sequence shown later includes installing a fluid sealing shell that covers the removable outer wall of the manhole.

[0041] [ Figure 5 ] Figure 5 Is Figure 3 and Figure 4 Following the sequence shown, a cross-sectional view of the manhole and its fluid sealing shell according to the present invention.

[0042] [ Figure 6 ] Figure 6 It is a schematic cross-sectional view of a conventional material orifice according to the prior art, which is equipped with a liquid dome.

[0043] [ Figure 7 ] Figure 7 The first sequence of installing material holes in a liquid dome according to the invention is shown in cross-section.

[0044] [ Figure 8 ] Figure 8 The cross-section shows the ratio Figure 6 The sequence shown later includes a mounting housing that covers the removable outer wall of the material orifice.

[0045] [ Figure 9 ] Figure 9 Is Figure 7 and Figure 8 Following the sequence shown, a cross-sectional view of the material pores and their shells according to the present invention.

[0046] [ Figure 10 ] Figure 10 This is a schematic cross-sectional view of the storage facilities of a methane tanker and the tanker's loading / unloading distribution station. Detailed Implementation

[0047] The term "vertical" refers to extending in the direction of Earth's gravitational field. The term "horizontal" refers to extending in a direction perpendicular to the vertical direction.

[0048] Figure 1A storage device 1 comprising a dual-support structure is schematically shown, the dual-support structure consisting of an inner support structure 2 and an outer support structure 3 surrounding the inner support structure 2. Inside the inner support structure 2, the storage device 1 includes a sealed and thermally insulated tank 71, which will be described below.

[0049] The internal support structure 2 and the external support structure 3 have multiple interconnected walls, specifically the internal upper support wall 4 and the external upper support wall 5 located at the top of the storage device 1, such as... Figure 1 As shown.

[0050] When the storage device 1 is placed on a ship such as a methane tanker, the supporting structures 2 and 3 are formed by the ship's double hull. Therefore, the inner upper supporting wall 4 is referred to as the ship's inner wall 4, while the outer upper supporting wall 5 is referred to as the ship's outer wall 5.

[0051] Tank 71 has a main structure formed by a bottom wall (not shown), a top wall 7, two dike walls 8, two side walls (not shown), and optionally two to four chamfered walls (not shown). The two dike walls connect the bottom wall to the top wall 7 and are located at the front and rear when the storage device 1 is on a ship. The two to four chamfered walls connect the side walls to the bottom wall or the top wall 7. Thus, the walls of tank 71 are interconnected to form a polyhedral structure and define the internal storage space.

[0052] In order to load and unload liquefied gas into and from the tank 71, the storage device 1 has a loading / unloading opening 10 that partially interrupts the outer upper support wall 5, the inner upper support wall 4 and the top wall 7 of the tank 71 so that a loading / unloading conduit (not shown in the figures) can reach the bottom of the tank 71 by passing through the opening 10.

[0053] The storage device 1 also includes a loading / unloading tower (not shown in the figures), which is disposed corresponding to the opening 10 and located inside the tank 71. The loading / unloading tower is formed over the entire height of the tank 71 for loading / unloading pipes (not shown in the figures) and support structures for pumps (not shown in the figures).

[0054] Furthermore, the storage device 1 has a cover 12 disposed in the loading / unloading opening 10 to close the internal storage space at the opening 10. The cover 12 includes an access hole that allows the loading / unloading pipe to pass through the cover 12, and includes two access through holes 20, 30, one of which is referred to as manhole 20 and the other as material hole 30.

[0055] Tank 71 also includes a shaft 15 located on the main structure and at the opening 10, which allows the tank wall to extend continuously from the inner wall panel 4 to the outer wall panel 5, which is interrupted at the loading / unloading opening 10. In the case of a liquefied gas storage tank, this shaft 15, specifically fitted with the cover 12, is referred to as a liquid dome.

[0056] The loading / unloading opening 10 and the shaft 15 have rectangular or square outlines. Therefore, the shaft 15 includes four walls, one of which is a continuation of the rear cofferdam wall 8 (e.g., Figure 1 (as shown), while the other three walls are connected to the top wall 7 at a 90° angle to the top wall.

[0057] Tank 71 is a membrane tank capable of storing liquefied gas. The main structure of tank 71 includes a multi-layer structure, which from the outside to the inside includes a secondary thermal insulation barrier 16 with insulating elements that abuts against the supporting structure, a secondary sealing membrane 17 that abuts against the secondary thermal insulation barrier 16, a main thermal insulation barrier 18 with insulating elements that abuts against the secondary sealing membrane 17, and a main sealing membrane 19 designed to contact the liquefied gas contained in tank 71.

[0058] According to one embodiment, the main structure of tank 71 is based on Mark The technology is manufactured using a technique described in detail in document FR-A-2691520.

[0059] In this main structure, the secondary thermal insulation barrier 16, the primary thermal insulation barrier, and the secondary sealing membrane 17 are essentially composed of panels juxtaposed on a supporting structure, which can be an inner supporting structure 2 or a structure that connects the inner upper supporting wall 4 to the outer upper supporting wall 5 at the opening 10. The secondary sealing membrane 17 is formed of a composite material comprising an aluminum sheet sandwiched between two glass fiber fabric sheets. The primary sealing membrane 19 itself is obtained by assembling multiple metal plates welded together along their edges and including corrugations (not shown in the figures) extending in two mutually perpendicular directions. The metal plates are made, for example, of stainless steel or aluminum sheets, formed by bending or pressing.

[0060] Further details of this corrugated metal film are described in FR-A-2861060.

[0061] Inside the shaft 15, the secondary sealing membrane 17 is fixed to the bearing structure at its end by using a connecting ring 21 protruding from the inner surface of the shaft bearing wall, which is the wall that connects the inner wall panel 4 to the outer wall panel 5 in this area.

[0062] The cover 12 has a multi-layered structure facing upwards, including an upper cover wall 22 and a thermally insulating structure 24. The cover 10 also includes a reinforcement 25 located on the upper cover wall 22.

[0063] The cover wall 22 is fixed to the outer wall panel 5 in a sealed manner around the opening 10, so that the cover wall 22 acts as a secondary sealing membrane 17. The cover wall 22 is made of a metal material, such as stainless steel.

[0064] The cover 12 is welded to the main sealing membrane 19 of the shaft 15 in a sealing manner, using a connector 26 in this example. Alternatively, the cover 12 can be welded directly to the sealing membrane 19 of the shaft 15.

[0065] The thermal insulation structure 24, as well as the upper portion of the shaft 15, the cover 12, and the opening 10, include multiple insulating elements juxtaposed on each other and may have similar or different constructions. These insulating elements may be so-called "structural" insulating elements, which inherently possess better or even superior mechanical integrity characteristics or performance than so-called "non-structural" insulating elements. Structural insulating elements may be constructed from optionally fiber-reinforced high-density polymer foam blocks, or from boxes made of plywood or composite materials filled with insulating fillers such as glass wool, polymer foam, or perlite. Non-structural insulating elements may be low-density polymer foam blocks or glass wool blocks.

[0066] like Figure 1 As shown, the manhole 20 and material hole 30 according to the present invention respectively include a first fluid sealing shell 41 and a second fluid sealing shell 42. The outer ends 46 and 47 of the first entry hole and the second entry holes 20 and 30 respectively open to the outside of the tank 71 at the top, while the inner ends 48 and 49 of the first entry hole and the second entry holes 20 and 30 respectively open to the tank 71 at the bottom.

[0067] The manhole 20 and material hole 30, as well as their respective fluid sealing shells 41 and 42, are described in more detail in the accompanying drawings.

[0068] Figure 2 A manhole according to the prior art is shown. This manhole 20 has an outer end 46 and an inner end 48, the outer end 46 being closed or sealed by a removable fluid-tight outer wall 50. Thermal insulation 52, such as polymer foam or glass wool, is disposed between the outer end 46 and the inner end 48 of the manhole 20.

[0069] like Figure 3 As shown, the manhole 20 is composed of a unit or assembly that can be inserted into a dedicated space in the upper portion of the shaft 15 that forms the liquid dome. Therefore, when an operator needs to enter the tank 71 or when it is advantageous for the operator to enter the tank, the mechanical fasteners are removed from the removable external part 50 of the manhole, and then the unit forming the manhole 20 is removed to allow the operator to enter the tank 71.

[0070] Figure 3A fixed (semi-)circular wall 55 is shown, in addition to the reinforcement 25 conventionally present on the outer surface of the liquid dome. The diameter of this wall is at least a few centimeters, or even tens of centimeters, larger than the diameter of the inlet hole 20. This wall 55 is added to the outer surface of the liquid dome, for example, by welding, to form a portion of the fixed wall for connecting the first fluid sealing shell 41.

[0071] from Figure 4 and Figure 5 As can be clearly seen, the removable chamber wall 56 forming the cover can be arranged on the upper end of the wall 55, or in other words, on the periphery of the wall 55, which may extend through a fixed additional wall 57 of the first shell 41, as... Figure 5 As shown in the diagram, the removable outer wall 56 is secured to the fixed walls 55, 56 in a sealed manner using screws or bolts (preferably with at least one additional seal), which also forms the fluid-sealed shell 20. The diameter of the removable chamber wall 56 is at least 10% larger than the diameter of the removable outer wall 50 of the manhole 20, allowing the operator to access the tank 71 first by removing the removable chamber wall 56 and then by removing or disassembling the fasteners of the removable outer wall 50 to remove the unit forming the manhole 20.

[0072] The fixed wall 55 and the removable exterior wall 56 of the first shell 41 are advantageously made of stainless steel.

[0073] The fluid-sealed housing 41 includes at least one communication channel 58 that allows inert gas present in the housing 41 to communicate with gas present in the insulated space formed by the primary thermal insulation barrier 18 and the secondary thermal insulation barrier 16 of the main structure of the tank 71. The cross-section of the communication channel 58 may be circular, rectangular, or even elliptical.

[0074] Preferably, the inert gas initially present in the shell 41 is the same inert gas that fills the insulated space formed by the primary thermal insulation barrier 18 and the secondary thermal insulation barrier 16 of the tank. In the presence of this or these connecting channels 58, once the storage device 1 has been installed in a structure such as the ship 70, the insulated space formed by the primary thermal insulation barrier 18 and the secondary thermal insulation barrier 16 of the tank 71 is filled with inert gas, such that the shell 41 is filled with inert gas via one or more connecting channels 58.

[0075] According to Figure 2 In a similar way, Figure 6 A conventional material orifice 30 according to the prior art is shown. The material orifice 30 comprises units, or in other words, assembled entities, which can be inserted into a dedicated space in the upper portion of the vertical shaft 15 forming a liquid dome. Therefore, when it is necessary to introduce material into the tank 71 or when it is advantageous to introduce material into the tank, the units forming the material orifice 30 are removed so that material can be introduced into the tank 71.

[0076] The material orifice 30 has a rectangular cross-section and a fluid-tight, removable outer wall 60, which forms a cover for the material orifice 30. The removable outer wall 60 of the material orifice 30 is secured in a sealing manner to a protrusion projecting from the outer surface of the liquid dome using bolts or screws. The cross-sectional shape of the protrusion is identical to that of the removable outer wall 60. When it is necessary to remove the material orifice 30, the fasteners of the fluid-tight, removable outer wall 60 are removed or disassembled, allowing the unit to be removed, such as... Figure 7 As shown.

[0077] Figure 7 Also shown is a retaining wall 61 belonging to the second fluid sealing shell 42, which extends in height beyond the removable outer wall 60 of the material orifice 30. This retaining wall 61, like the retaining wall 55 of the first shell 20, can at least partially retain the reinforcement 25 normally present on the upper or outer surface of the liquid dome. Figure 8 As shown, the wall 61 is used to accommodate a removable chamber wall 65, which is installed using screws or bolts in a sealed manner (possibly with added seals).

[0078] The fixed wall 61 and the removable unloading chamber wall 65 of the second shell 42 are advantageously made of stainless steel.

[0079] The dimensions of the removable chamber wall 65 (in this example, only the width and length are considered) are at least 10% larger than the dimensions of the removable outer wall 60 of the material hole 30, such that material can be easily introduced into the tank 71 by first removing the removable chamber wall 65 and then removing the fasteners of the removable outer wall 60 to remove the unit forming the material hole 30.

[0080] like Figure 8 and Figure 9 As shown, the second fluid sealing shell 42 for the material orifice 30 includes at least two communicating channels 66 that allow the inert gas present in the shell 42 to communicate with the thermal insulation space of the main structure, such that the inert gas in the shell 42 and the inert gas of the main structure are mixed together. This space is formed by the primary thermal insulation barrier 18 and the secondary thermal insulation barrier 16 of the tank 71. The properties of this inert gas in the fluid sealing shell 42 are advantageously the same as those of the inert gas present in the fluid sealing shell 41.

[0081] Figure 10An example of a marine distribution station including a loading and unloading station 75, an underwater pipeline 76, and a land-based facility 77 is shown. The loading and unloading station 75 is a fixed marine facility comprising a boom 74 and a tower 78 supporting the boom 74. The boom 74 carries a bundle of insulated flexible hoses 79, which can be connected to the loading / unloading pipeline 73. The directional boom 74 is adaptable to methane tankers of all sizes. A connecting pipeline (not shown) extends inside the tower 78. The loading and unloading station 75 enables the loading of methane carriers 70 from or unloading methane carriers onto the land-based facility 77. The land-based facility has a liquefied gas storage tank 80 and a connecting pipeline 81 connected to the loading and unloading station 75 via the underwater pipeline 76. The underwater pipeline 76 enables the transport of liquefied gas between the loading and unloading station 75 and the land-based facility 77 over long distances (e.g., 5 km), allowing the methane tanker 70 to remain at a long distance from the coast during loading and unloading operations.

[0082] To generate the pressure required for transporting liquefied gas, pumps carried on the vessel 70 and / or pumps equipped on the land-based equipment 77 and / or pumps equipped on the loading and unloading station 75 are used.

[0083] Although the invention has been described in conjunction with several specific embodiments, it is apparent that the invention is not limited thereto and includes all technical equivalents of the described apparatus and combinations thereof (if these are within the scope of the invention).

[0084] The use of the verbs “comprising,” “showing,” or “including,” and their variations, does not exclude the presence of elements or steps that differ from those described in the claims.

[0085] Any reference numerals in parentheses in the claims should not be construed as limiting the claims.

Claims

1. A storage device (1) for liquefied gas, the storage device comprising a support structure (2, 3) and a sealed and thermally insulated tank (71) disposed inside the support structure (2, 3). The sealed and thermally insulated tank (71) includes a main structure formed by a plurality of tank walls interconnected and fixed to the support structure (2, 3), the main structure defining an internal storage space, the main structure including at least one sealing membrane (17, 19) and at least one thermally insulating barrier (16, 18) disposed between the sealing membrane (17, 19) and the support structure (2, 3); The load-bearing structure (2, 3) includes a flat upper load-bearing wall (4, 5). The sealing membrane (17, 19) and the thermal insulation barrier (16, 18) of the main structure, as well as the upper bearing wall (4, 5), are partially interrupted to define a loading / unloading opening (10), which includes at least a removable first entry through-hole and a removable second entry through-hole (20, 30), the removable first entry through-hole and the removable second entry through-hole having inner ends (48, 49) and outer ends (46, 47), the outer ends (46, 47) being fitted with a removable outer wall (50). Its features are, The device (1) includes at least a first fluid sealing shell (41) surrounding the outer end (46) of the first inlet hole (20), a removable outer wall (50) of the first inlet hole (20) forming the wall of the first fluid sealing shell (41), and the first fluid sealing shell (41) being filled with an inert gas.

2. The storage device (1) according to claim 1, wherein, The device includes a second fluid sealing shell (42) surrounding the outer end (47) of the second inlet hole (30), a removable outer wall (60) of the second inlet hole (30) forming the wall of the second fluid sealing shell (42), and the second fluid sealing shell (42) being filled with an inert gas.

3. The storage device (1) according to claim 2, wherein, The first fluid sealing shell and / or the second fluid sealing shell (41, 42) are secured by a seal that is welded to the outer surface of the storage device (1).

4. The storage device (1) according to claim 2 or 3, wherein, The first fluid sealing shell and the second fluid sealing shell (41, 42) each include a removable first chamber wall and a removable second chamber wall (56, 65), the dimensions of which are larger than the dimensions of the removable outer walls (50, 60) of the first inlet through hole and the second inlet through hole (20, 30).

5. The storage device (1) according to claim 2 or 3, wherein, The removable outer walls (50, 60) of the first and second access holes (20, 30) are fixed in a sealed manner by using a mechanical device.

6. The storage device (1) according to claim 2 or 3, wherein, The loading / unloading opening (10) includes a cover (12) forming a main sealing membrane, through which the first inlet and the second inlet (20, 30) pass and are fixed to the cover (12) in a sealing manner.

7. The storage device (1) according to claim 2 or 3, wherein, The first fluid sealing shell and / or the second fluid sealing shell (41, 42) have at least one communication channel (58, 66) for communicating with the thermal insulation barrier (16, 18) of the main structure.

8. The storage device (1) according to any one of claims 1 to 3, wherein, The inert gas is composed of molecular nitrogen.

9. The storage device (1) according to claim 6, wherein, The cover of the loading / unloading opening (10) is directly or indirectly fixed to the main sealing membrane of the main structure.

10. The storage device (1) according to claim 9, wherein, When the cover is directly fixed to the main sealing membrane of the main structure, welding is used to achieve the fixation.

11. The storage device (1) according to claim 9, wherein, When the cover (12) is indirectly fixed to the main sealing membrane, it is fixed using a connector (26) which is welded to the sealing membrane (19) of the main structure and the cover (12) in a sealing manner.

12. The storage device (1) according to any one of claims 9 to 11, wherein, The cover (12) includes: - A plurality of flat metal plates, assembled together, wherein the flat metal plates have a coefficient of thermal expansion between 0.5 and 10. -6 By 2.10 -6 K -1 Made of an alloy of iron and nickel, or - Multiple corrugated metal sheets, which are arranged in a repeating array and welded together in a sealed manner, the metal sheets being made of stainless steel.

13. The storage device (1) according to claim 5, wherein, The first fluid sealing shell and the second fluid sealing shell (41, 42) respectively include a removable first chamber wall and a removable second chamber wall (56, 65), and the removable outer walls (50, 60) of the first inlet through hole and the second inlet through hole (20, 30) are fixed in a sealed manner together with the removable first chamber wall and the removable second chamber wall (56, 65) by means of a mechanical device.

14. A vessel (70) for transporting cold liquid products, the vessel having a double hull (72) and a storage device (1) according to any one of claims 1 to 13, the storage device being arranged in the double hull.

15. A conveying system for conveying cold liquid products, the system comprising a vessel (70) according to claim 14, insulated conduits (73, 79, 76, 81), and a pump, the insulated conduits being arranged to connect a tank (71) mounted in the double hull to a floating or land-based external storage device (77), the pump being used to convey a flow of cold liquid products from the floating or land-based external storage device to the tank of the vessel or from the tank of the vessel to the floating or land-based external storage device via the insulated conduits.

16. A method for loading or unloading the vessel (70) according to claim 14, wherein, Cold liquid products are supplied from a floating or land-based external storage device (77) to the vessel's tank (71) or from the vessel's tank to a floating or land-based external storage device via insulated conduits (73, 79, 76, 81).

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