Liquid dome for storage tank of liquefied gas

Abstract

The invention relates to a storage unit (1) for liquefied gas and a sealed and insulated tank (71) comprising a loading / unloading opening (10) having an upper cover wall (23), a lower cover wall (22) and an insulation structure (24) located between the lower cover wall (22) and the upper cover wall (23), the pipe (30) and the upper cover wall (23) being made of different types of iron-based alloys and at least one attachment lug (50) extending from the upper cover wall (23) being attached to the lower cover wall (22) in a sealed manner, directly or indirectly.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of storage equipment for liquefied gas, comprising a sealed and insulated membrane tank. In particular, the present invention relates to the field of sealed and insulated tanks for storing and / or transporting liquefied gas at cryogenic temperature, such as tanks for transporting, for example, liquefied petroleum gas (also known as LPG) at a temperature comprised between -50°C and 0°C, or tanks for transporting liquefied natural gas (LNG) at about -162°C at atmospheric pressure. These tanks can be installed on shore or on floating structures. In the case of floating structures, the tanks can be used to transport or receive liquefied gas used as fuel to propel the floating structure. BACKGROUND

[0002] Document FR 2 991 430 describes a storage equipment for liquefied gas, comprising a sealed and insulated tank, integrated into a load-bearing structure constituted by the double hull of a ship. Each wall of the tank comprises a secondary insulating barrier, a secondary sealing membrane, a primary insulating barrier and a primary sealing membrane.

[0003] In the region located at the top of the tank, the tank has a protruding portion in the form of a chimney cylinder, called a liquid dome. In this region, the load-bearing structure is locally interrupted to delimit a loading / unloading opening through which fluid loading / unloading pipes are intended to pass. This loading / unloading opening, called a liquid dome, comprises an insulating or thermally insulating barrier and elements forming a primary sealing membrane.

[0004] It is desirable to reduce the production costs associated with the production of such a liquid dome, in particular by using less expensive materials, but the properties of these materials are less suitable for the very low temperatures encountered by the tank and such a liquid dome. In addition, the tank is installed in a structure, such as a ship, which is subjected to very large mechanical stresses, which twist and bend according to the environmental conditions of the structure, these mechanical loads being particularly detrimental to the structure of the liquid dome, which extends vertically above the tank filled with liquefied gas in the form of a relatively narrow chimney cylinder.

[0005] After various experiments and tests, the Applicant has found that it is possible to envisage a liquid dome pipe made of a less expensive metal material, provided that a particular structure is created to enable the liquid dome to withstand the huge stresses that it must absorb.

[0006] The Applicant first intended to propose a liquid dome which is less expensive, but which is able to withstand all the stresses to which it is subjected, while providing a perfect sealing, both physically and thermally, of the extremely cold fluid contained in the tank. SUMMARY

[0007] The present application therefore relates to a storage device for liquefied gas, comprising a load-bearing structure and a sealed and insulated tank arranged in the load-bearing structure, the sealed and insulated tank comprising a main structure formed by a plurality of tank walls connected to each other and fixed to the load-bearing structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane and at least one insulating barrier placed between the sealing membrane and the load-bearing structure; the load-bearing structure comprising a substantially planar upper load-bearing wall; the sealing membrane, the insulating barrier of the main structure and the upper load-bearing wall being locally interrupted to delimit a duct forming a load-bearing wall of a cylinder which extends along a vertical axis to an upper end comprising a loading / unloading opening through which a fluid loading / unloading duct is intended to pass, wherein the tank comprises a lid placed in the loading / unloading opening and wherein the lid comprises an upper lid wall, a lower lid wall and an insulating structure located between the lower lid wall and the upper lid wall.

[0008] The present application is characterized in that the duct and the upper lid wall are made of iron-based alloys of different natures and in that at least one fixing tab originating from the upper lid wall is fixed to the lower lid wall in a sealed manner, directly or indirectly.

[0009] The present application therefore relates to a storage device for liquefied gas, comprising a load-bearing structure and a sealed and insulated tank arranged in the load-bearing structure, the sealed and insulated tank comprising a main structure formed by a plurality of tank walls connected to each other and fixed to the load-bearing structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane and at least one insulating barrier placed between the sealing membrane and the load-bearing structure; the load-bearing structure comprising a substantially planar upper load-bearing wall; the sealing membrane, the insulating barrier of the main structure and the upper load-bearing wall being locally interrupted to delimit a duct forming a load-bearing wall of a cylinder which extends along a vertical axis to an upper end comprising a loading / unloading opening through which a fluid loading / unloading duct is intended to pass, wherein the tank comprises a lid placed in the loading / unloading opening and wherein the lid comprises an upper lid wall, a lower lid wall and an insulating structure located between the lower lid wall and the upper lid wall.

[0010] By doing so, the present application makes it possible to achieve significant savings in the production of the liquid dome, while ensuring or maintaining an effective sealing of the liquefied gas and an excellent mechanical resilience of the dome to all stresses to which the region is generally subjected.

[0011] The term "duct" is understood to mean that the duct forms an outer wall of the liquid dome, more particularly a wall of the cylinder opening into the tank containing the liquefied gas.

[0012] By convention, the terms "external" and "internal" are used to define the relative position of an element with respect to another element with reference to the inside and outside of the tank.

[0013] Other advantageous features of the present application are briefly described below:

[0014] Advantageously, the fixing tab has an L-shaped cross-section and comprises a linear proximal portion originating from the upper lid wall, the linear proximal portion being prolonged by a distal portion starting from the proximal portion at an angle of 90° ± 10°.

[0015] Advantageously, the thermal barrier is a secondary thermal barrier, and the sealing film comprises in succession from the inside of the tank towards the pipe a primary sealing film and a secondary sealing film, the primary thermal barrier being placed between the primary sealing film and the secondary sealing film, and the fixing tab is also fixed to the secondary sealing film in a sealed manner.

[0016] Thus, the fixing tab is connected not only to the lower lid wall, which forms the primary film of the opening of the liquid dome, in a sealed manner, but also to the thermal sealing structure, in this example the secondary sealing film. This arrangement makes it possible to firmly and flexibly fix, on the one hand, the main structure of the tank, and on the other hand the lower lid wall, which forms the primary film of the opening of the liquid dome, to the upper lid wall, which like the fixing tab is made of a material that is particularly strong from a mechanical point of view and has a very low coefficient of thermal expansion.

[0017] According to a preferred embodiment, the fixing of the fixing tab to the secondary sealing film is performed at the distal end portion of the fixing tab.

[0018] According to a preferred embodiment of the application, the fixing of the fixing tab to the secondary sealing film is achieved by adhesion.

[0019] According to another embodiment, it is also conceivable to use welding to achieve this fixing, in particular in the case where the secondary sealing film is a metal or a material that can be assembled with a metal material. In this case, the fixing of the fixing tab to the secondary sealing film is achieved using a sealing weld.

[0020] According to one embodiment of the application, when the fixing tab is fixed directly to the lower lid wall, the fixing is achieved by welding at the proximal end portion of the fixing tab.

[0021] In this case, advantageously, the primary sealing film is fixed to the lower lid wall in a sealed manner, preferably by welding.

[0022] According to one embodiment of the application, when the fixing tab is fixed indirectly to the lower lid wall, a connecting piece connects the lower lid wall, the sealing film and the fixing tab in a sealed manner.

[0023] In this case, as a preference, the fixing tab has a flange, which originates from the proximal end portion and extends at an angle of 90° ± 10° with respect to the proximal end portion, the connecting piece being fixed to the flange of the fixing tab.

[0024] Advantageously, the pipe is made of carbon steel. Thus, the pipe is made of an iron-based alloy, and the pipe contains 0% < C < 2.11% by weight. As a preference, the carbon content can be included in the range 0% < C < 0.8%, more particularly in the range 0% < C < 0.5%, depending on the sought weldability properties.

[0025] The composition of the carbon steel can comprise other elements. The sum of these elements is preferably less than or equal to 5% so that the steel is lightly alloyed. Thus, the carbon steel can also contain 0% < Mn < 2%, 0% < Si < 0.5% by weight.

[0026] According to one embodiment, the pipe is made of an iron-based alloy containing 0% < C < 0.21%, 0% < Mn < 1%, 0% < Si < 0.5%, 0% < P < 0.035% and 0% < S < 0.035% by weight, the remainder being iron and unavoidable impurities resulting from the production of iron.

[0027] As a preference, the pipe is made of a steel of grade A, B, D, AH, DH, EH, FH or E according to the IGC Code, the IGC Code being the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, which is well known to the person skilled in the art.

[0028] Advantageously, the upper cover wall and the fixing tabs are made of an iron-based alloy comprising an austenitic steel containing 0 < C < 0.08%, 0% < Mn < 2%, 0% < Si < 0.5%, 0% < P < 0.045%, 0% < S < 0.030%, 8% < Ni < 14%, 16% < Cr < 50%, 0% < N < 0.02%, optionally 0% < Mo < 3% and / or 0% < Ti < 0.7% by weight, the remainder being iron and unavoidable impurities resulting from the production of iron.

[0029] By way of convention, the elements of the periodic table of the elements are considered, namely:

[0030] C: Carbon; Cr: Manganese; Cr: Chromium; Si: Silicon; Ni: Nickel; Co: Cobalt; P: Phosphorus; O: Oxygen; N: Nitrogen; Mo: Molybdenum; S: Sulfur and Ti: Titanium.

[0031] Advantageously, the lower cover wall comprises:

[0032] - a plurality of planar metal sheets assembled to each other, the planar metal sheets being made of an iron-nickel alloy having a coefficient of thermal expansion of between 0.5.10 -6 K -1 and 2.10 -6 K -1 or

[0033] - a plurality of undulating metal sheets juxtaposed in a repeating pattern and welded together in a sealed manner, the metal sheets being made of stainless steel. Here, it can be noted that the undulating metal sheets can be made of high manganese steel, the term "stainless steel" encompassing this alloy.

[0034] Thus, the lower cover wall can have an undulating portion similar to Figure 3 andFigure 4 The corrugations visible on the main film of the central structure, and which are intended to provide mechanical integrity when the metal used to make the sheet expands due to the very cold temperature in the tank, or the lower cover wall can comprise a plate having a very low coefficient of thermal expansion, for example made of Invar® .

[0035] The present invention relates to a ship for transporting a cold liquid product, having a double hull and a storage installation as described above, arranged in the double hull.

[0036] The present invention also relates to a delivery system for delivering a cold liquid product, comprising a ship as described above, an insulated pipe assembly arranged in such a way as to connect a tank installed in the hull of the ship to a floating or onshore external storage installation, and a pump for delivering a flow of cold liquid product from the floating or onshore external storage installation to the tank of the ship, or vice versa, through the insulated pipe assembly.

[0037] Finally, the present invention relates to a method of loading or unloading from a ship as described above, in which a cold liquid product is delivered from a floating or onshore external storage installation to the tank of the ship, or vice versa, through an insulated pipe assembly. BRIEF DESCRIPTION OF DRAWINGS

[0038] The present invention will be better understood from the following description of several specific embodiments thereof, given by way of non-limiting example only, with reference to the accompanying drawings in which:

[0039] [ Figure 1 ] Figure 1 is a cross-sectional view of a liquid dome according to an embodiment of the present invention.

[0040] [ Figure 2 ] Figure 2 is an enlarged view of a corner portion of the liquid dome of Figure 1 .

[0041] [ Figure 3 ] Figure 3 is a schematic view showing a first angular view of the elements of the liquid dome shown in Figure 1 .

[0042] [ Figure 4 ] Figure 4 is a schematic view showing a second angular view of the elements of the liquid dome shown in Figure 1 .

[0043] [ Figure 5 ]Figure 5 is a liquid dome according to a further embodiment of the application and Figure 2 is a cross-sectional view of the same parts of the liquid dome of

[0044] [ Figure 6 ] Figure 6 is a liquid dome according to a further embodiment of the application and Figure 2 is a cross-sectional view of the same parts of the liquid dome of

[0045] [ Figure 7 ] Figure 7 is a schematic cross-sectional view of a storage installation of a methane carrier and of a terminal for loading / unloading from the tank. DETAILED DESCRIPTION

[0046] The term "vertical" means here extending along the direction of the gravitational field of the earth. The term "horizontal" means here extending along a direction perpendicular to the vertical direction.

[0047] When the storage installation 1 is positioned on a ship, such as a methane carrier, a load bearing structure (not shown in the figures) is formed by the double hull of the ship. The outer upper load bearing wall 5 is referred to as the outer deck 5 of the ship.

[0048] The tank 71 has a main structure formed by a bottom wall (not shown), a top wall and two cofferdam walls (not shown in the figures) connecting the bottom wall to the top wall and located at the front and at the rear when the storage installation 1 is located on a ship, two side walls (not shown) and optionally two to four chamfer walls (not shown) connecting the side walls to the bottom wall or to the top wall, which are not shown in the figures. The walls of the tank 71 are thus connected to each other to form a polyhedral structure and to delimit the internal storage space 9.

[0049] For loading and unloading liquefied gas into and from the tank 71, the storage installation 1 has a loading / unloading opening 10 which partially interrupts the outer upper load bearing wall 5, the inner upper load bearing wall and the top wall of the tank 71 so as to enable, in particular, a loading / unloading pipe (not shown in the figures) to pass through this opening 10 to reach the bottom of the tank 71.

[0050] The storage installation 1 also comprises a loading / unloading tower (not shown in the figures) positioned according to the opening 10 and located inside the tank 71, which forms a support structure for the pumps (not shown) and for the loading / unloading pipe over the entire height of the tank 71.

[0051] Furthermore, the storage installation 1 has a cover 12 which is arranged in the loading / unloading opening 10 to close the internal storage space at said opening 10. The cover 12 has an aperture which enables the loading / unloading pipe to pass through the cover 12.

[0052] The tank 71 comprises a cylinder 15 which is seated on the main structure at the opening and which enables the tank wall to extend continuously from the internal deck to the external deck 5, these decks being interrupted by the loading / unloading opening 10. In the case of a liquefied gas storage tank, this cylinder 15 fitted with said cover 12 is called a liquid dome.

[0053] The loading / unloading opening 10 and the cylinder 15 generally have a rectangular profile. Thus, the cylinder 15 comprises four walls, one of which is a continuation of the rear bulkhead wall 8 (as shown) and the other three of which are connected to the top wall so as to be at 90° to the top wall. Figure 1

[0054] In the context of the application, the cover 12 is at the external deck 5, that is to say, such that the cover closes or seals the cylinder 15. The tank 71 is a membrane tank 71 which is able to store liquefied gas. The main structure of the tank 71 comprises a multilayer structure which has, from the outside to the inside: a secondary thermal insulation barrier 16 having insulating elements, which is borne against the load-bearing structure; a secondary sealing membrane 17, which is borne against the secondary thermal insulation barrier 16; a primary thermal insulation barrier 18 having insulating elements, which is borne against the secondary sealing membrane 17; and a primary sealing membrane 19, which is intended to be in contact with the liquefied gas contained in the tank 71.

[0055] According to one embodiment, the main structure of the tank 71 is produced according to the Mark technology, which is described in particular in document FR-A-2 691 520.

[0056] In this main structure, the secondary thermal insulation barrier 16, the primary thermal insulation barrier and the secondary sealing membrane 17 essentially consist of a panel which is juxtaposed on the load-bearing structure, which can be an internal load-bearing structure, or a structure which connects the internal upper load-bearing wall to the external upper load-bearing wall 5 at the opening 10. The secondary sealing membrane 17 is formed from a composite material comprising an aluminium sheet sandwiched between two glass fibre fabric sheets. The primary sealing membrane 19 is obtained, in part, by assembling a plurality of metal sheets which are welded to one another along their edges and which comprise corrugations which extend in two perpendicular directions to one another. The metal sheets are made, for example, from stainless steel sheets or aluminium sheets, shaped by bending or pressing. The primary sealing membrane 19 is shown in particular in documents FR-A-2 691 520 and FR-A-2 691 521. Figure 3 and Figure 4

[0057] ​​Further details of such corrugated metal film are particularly described in FR-A-2861060.

[0058] In the drum 15, the secondary sealing film 17 is fixed at its upper end to a fixing tab 50, more particularly at a distal portion 51 of said tab 50. Advantageously, the connection between the fixing tab 50 and the secondary film 17 is achieved by sealing collage, possibly by welding.

[0059] The lid 12 also comprises a multilayer structure comprising, from the outside to the inside, an upper lid wall 23, a lower lid wall 22 and a thermal insulation structure 24 located between the lower lid wall 22 and the upper lid wall 23. The lid 12 also comprises a reinforcement 25 located on the upper lid wall 23.

[0060] The lid 12 is placed in the loading / unloading opening 10 in such a way that the upper lid wall 23 is positioned in the plane of the outer load-bearing wall 5 or of the outer deck 5. Thus, in this example, the storage installation 1 does not have a dome base and the lid 12 does not protrude above the outer deck 5.

[0061] The upper lid wall 23 is fixed to the outer deck 5 in a sealed manner around the opening 10, so that the upper lid wall 23 plays the role of the secondary sealing film 17 as far as the lid 12 is concerned. The upper lid wall 23 is produced using a metal material, for example stainless steel.

[0062] The lower lid wall 22 is welded to the main sealing film 19 of the main structure, in this example the drum 15, in a sealed manner using a connecting piece 26. According to various embodiments of the application, the connecting piece 26 is described in more detail in Figures 2 to 5 The connecting piece 26 is described in more detail in. The lower lid wall 22 is also welded in particular in a sealed manner to the loading / unloading duct.

[0063] The thermal insulation structure 24 of the lid 12 comprises a plurality of insulating elements which are juxtaposed with each other and which can have similar or different configurations. In a preferred embodiment, the insulating elements positioned according to the lower lid wall 22 and the connecting piece 22 are structural insulating elements, while the insulating elements located at the periphery of the thermal insulation structure 24 are non-structural insulating elements. The structural insulating elements can comprise: high-density polymer foam blocks, optionally reinforced with fibers; or boxes made of plywood or composite, filled with insulating filler such as glass wool or perlite. The non-structural insulating elements can be low-density polymer foam blocks or glass wool blocks.

[0064] The fixing tab 50 originates from the upper cover wall 23 and extends vertically, having a vertical proximal portion 51 and a distal portion 52 which extends horizontally or forms a C-shaped hook. Advantageously, the fixing tab 15 is thus made of the same material as the upper cover wall 23. It is thus made of a metallic material, generally a ferrous alloy, which has better mechanical integrity when the ambient temperature is substantially below 0°C, or even less than or equal to -40°C.

[0065] The upper cover wall 23 and thus the fixing tab 50 can thus be composed of a stainless steel of the 300 series authorized by the IGC specifications. In other words, the fixing tab 50 is composed of an austenitic steel according to the ASTM A240 standard.

[0066] The invention first lies in the fact that, thanks to the presence of the fixing tab 50, the pipe 30 which forms the cylinder 15 of the liquid dome is produced from a steel called carbon steel, in particular comprising a steel according to the ASTM A131 standard of A, B, D, AH, DH, EH, FH or E grades.

[0067] This arrangement thus makes it possible to reduce the amount of expensive stainless steel in the liquid dome and to impart flexibility to the primary anchoring points, that is to say, the anchoring to the lower cover wall 22 which forms the primary membrane at the opening 10 of the liquid dome and to the anchoring to the primary membrane 19, and to the secondary anchoring points, that is to say, the anchoring to the secondary membrane 17.

[0068] The main key aspect of the invention thus lies in the connection and fixing of the lower cover wall 22 to the fixing tab 50. Furthermore, this fixing tab is offset by at least a few centimetres with respect to the pipe 30 of the cylinder 15 of the liquid dome, that is to say, it is placed at a distance of 5 to 35 cm from the pipe 5, preferably at a distance of between 15 and 25 cm. This offset of the fixing tab 50 with respect to the pipe 30 induces a flexible fixing of the lower cover wall 22, making it possible for the assembly to easily absorb significant mechanical stresses, notably when the structure which houses the tank 71 is a ship, the region of the cylinder 15 of the liquid dome being subjected to high mechanical stresses and tensions due to the size of the region of the cylinder which is much smaller or narrower than the tank 71 and due to the vertical position of the region of the cylinder.

[0069] As can be seen in the attached drawings, the offset of the fixing tab 50 with respect to the duct 30 makes it possible to reduce the use of structural insulations 40, which are more expensive and difficult to arrange than other non-structural insulations 41. Thus, in the liquid dome structure according to the application, the amount of structural insulations 40 is slightly reduced compared to a conventional liquid dome without fixing tab 50.

[0070] The second aspect of the application is that the fixing tab can be connected directly or indirectly to the lower cover wall 22. Thus, as Figures 1 to 5 illustrated, when this fixing is indirect, a connecting piece 26 can be used, while when the fixing is direct, an embodiment such as Figure 6 illustrated.

[0071] As can be seen in Figures 1 to 5 , the connecting piece 26 comprises a first flange 27 welded in a sealed manner to the main sealing membrane 19 of the main structure, a second flange 28 connected to the first flange 27 and welded in a sealed manner to the lower cover wall 22 around the lower cover wall 22, and a third flange 29 connected to the flange 53 extending horizontally from the proximal portion 51. The flange 53 is derived from the fixing tab 50 and advantageously made of the same material as these portions 51, 52.

[0072] Figure 3 and Figure 4 show non-essential complementary elements of the liquid dome according to the application. These drawings in particular show undulations 60 present on the main membrane 19 of the main structure of the tank 71. These undulations 60 make it possible for the main membrane 19 to withstand the thermal expansion of this membrane 19 when the tank 71 is filled with liquefied gas at very low temperature, far below 0°C.

[0073] In this example, the distal portion 52 has an inverted C-shaped cross section, such that one part of this distal portion 52 is fixed by welding to the secondary membrane 17, while another part of this distal portion 52 is in contact with the secondary insulating barrier 16 and limits the space of this barrier 16 in the cylinder 15.

[0074] The flange 53 of the fixing tab 50 extends horizontally, that is to say at an angle of 90° ± 10° with respect to the proximal portion 51, to approach the connecting piece 26 or directly the lower cover wall 22, the latter embodiment (where there is no connecting piece 26 but a flange 53 protruding from the proximal portion 51) not being illustrated in the attached drawings but being conceivable within the scope of the application.

[0075] Figure 5An embodiment of the application is depicted in which the essential difference lies in the absence of a flange 53 originating from the proximal portion 51. In this embodiment, the flange 29 of the connection piece 26 extends until the flange comes into abutment with the proximal portion 51 of the fixation tab 50. As in the other embodiments, this flange 29 of the connection piece 26 is fixed to the proximal portion 51 of the fixation tab 50 by means of a seal weld. Thus, in this embodiment, the flange 29 of the connection piece 26 is much longer than in the other embodiments, and the flange 29 here generally has a length of at least fifteen centimetres, preferably of the order of twenty centimetres.

[0076] Figure 6 An embodiment is shown in which there is no connection piece 26, so that the fixing between the fixation tab 50 and the lower cover wall 22 is called a "direct" fixing. Thus, in this embodiment, the flange 53 of the fixation tab 50 extends until this flange encounters and fixes the lower cover wall 22, otherwise, as shown, the lower cover wall 22 extends until the lower cover wall comes into abutment with the fixation tab 50. In either of these embodiments, in the absence of a connection piece 26, the fixation tab 50 and the lower cover wall 22 are fixed together in a sealed manner, preferably using a weld. Figure 6

[0077] In the embodiment of Figure 6 , the main membrane 19 of the main structure has a flat portion 19' at the end of the main membrane, that is to say an L-shaped end portion, which bears on or abuts the lower cover wall 22, so that the welded connection between the lower cover wall 22 and the main membrane 19 is completely sealed. The other features of the application in their variants are not distinguished from the features previously described in the context of the other embodiments.

[0078] Figure 7 An example of a marine terminal is shown, comprising a loading and unloading station 75, an underwater pipeline 76 and onshore facilities 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 supporting the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible hoses 79 which can be connected to a loading / unloading pipeline assembly 73. The orientable mobile arm 74 is suitable for all sizes of methane transport ships. Connection pipelines (not shown) extend within the tower 78. The loading and unloading station 75 enables loading and unloading from the methane transport ship 70 to the onshore facilities 77 or vice versa. The onshore facilities have a liquefied gas storage tank 80 and a connection pipeline 81 which is connected to the loading or unloading station 75 through the underwater pipeline 76. The underwater pipeline 76 enables long distance (e.g. 5 km) transport of liquefied gas between the loading or unloading station 75 and the onshore facilities 77, thus enabling the methane transport ship 70 to remain long distances away from the shore during the loading and unloading operations.

[0079] ​To generate the pressure required to deliver the liquefied gas, use is made of pumps carried on board the vessel 70 and / or of pumps equipped on the shore installation 77, and / or of pumps equipped on the loading and unloading station 75.

[0080] Although the application has been described in connection with a number of specific embodiments, it will be evident that the application is not limited to these and that modifications are possible which will be apparent to those skilled in the art without departing from the scope of the application, and that the application includes all technical equivalents of the devices described and their combinations if these are within the scope of the application.

[0081] The use of the verb "comprise" or "to comprise", or "comprising", or "include", or "including" or "contains" or "containing" and variations thereof, does not exclude the presence of elements or steps other than those stated in the claims.

[0082] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A storage plant (1) for liquefied gas, comprising a load-bearing structure and a sealed and insulated tank (71) arranged in the load-bearing structure, the sealed and insulated tank (71) comprising a main structure formed by a plurality of tank walls connected to each other and fixed to the load-bearing structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane (17, 19) and at least one insulating barrier (16, 18) placed between the sealing membrane (17, 19) and the load-bearing structure; the load-bearing structure comprising an upper load-bearing wall which is substantially planar; Said sealing membranes (17, 19), said thermally insulating barrier (16, 18) of said main structure and said upper load bearing wall are locally interrupted to delimit a duct (30) which forms a load bearing wall of a cylinder (15) which extends along a vertical axis to an upper end which comprises a loading / unloading opening (10) through which a fluid loading / unloading duct is intended to pass, wherein, the sealed and insulated tank (71) comprising a lid (12) placed in the loading / unloading opening (10) and wherein the lid (12) comprises an upper lid wall (23), a lower lid wall (22) and an insulating structure (24) located between the lower lid wall (22) and the upper lid wall (23), characterized in that the pipe (30) and the upper lid wall (23) are made of iron-based alloys of different nature and at least one fixing tab (50) deriving from the upper lid wall (23) is fixed, in a sealed manner, directly or indirectly to the lower lid wall (22).

2. The storage device (1) according to claim 1, wherein the fixing tab (50) has an L-shaped cross section and comprises a linear proximal portion (51) deriving from the upper lid wall (23), which is prolonged by a distal portion (52) starting from the linear proximal portion (51) at an angle of 90° ± 10°.

3. The storage device (1) according to claim 1 or 2, wherein the insulating barrier is a secondary insulating barrier (16) and the sealing membrane (17, 19) comprises, in succession from the inside of the sealed and insulated tank (71) towards the pipe, a primary sealing membrane (19) and a secondary sealing membrane (17), a primary insulating barrier (18) being placed between the primary sealing membrane (19) and the secondary sealing membrane (17) and wherein the fixing tab (50) is also fixed, in a sealed manner, to the secondary sealing membrane (17).

4. The storage device (1) according to claim 2, wherein the insulating barrier is a secondary insulating barrier (16) and the sealing membrane (17, 19) comprises, in succession from the inside of the sealed and insulated tank (71) towards the pipe, a primary sealing membrane (19) and a secondary sealing membrane (17), a primary insulating barrier (18) being placed between the primary sealing membrane (19) and the secondary sealing membrane (17) and wherein the fixing tab (50) is also fixed, in a sealed manner, to the secondary sealing membrane (17), wherein the fixing of the fixing tab (50) to the secondary sealing membrane (17) is performed at the distal portion (52) of the fixing tab (50).

5. The storage device (1) according to claim 3, wherein the fixing of the fixing tab (50) to the secondary sealing membrane (17) is achieved by gluing. the fixing of the fixing tab (50) to the secondary sealing membrane (17) is achieved by gluing.

6. The storage device (1) according to claim 2, wherein When the fixing tab (50) is fixed directly to the lower cover wall (22), the fixing is achieved by welding at the linear proximal portion (51) of the fixing tab (50).

7. The storage device (1) according to claim 3, wherein The main sealing membrane (19) is fixed to the lower cover wall (22) in a sealed manner by welding.

8. The storage device (1) according to claim 1 or 2, wherein When the fixing tab (50) is fixed indirectly to the lower cover wall (22), a connector (26) connects the lower cover wall (22), the sealing membrane (19) and the fixing tab (50) in a sealed manner.

9. The storage device (1) according to claim 2, wherein, When the fixing tab (50) is fixed indirectly to the lower cover wall (22), a connector (26) connects the lower cover wall (22), the sealing membrane (19) and the fixing tab (50) in a sealed manner, wherein the fixing tab (50) comprises a flange (53) originating from the linear proximal portion (51) and extending at an angle of 90° ± 10° with respect to the linear proximal portion (51), the connector (26) being fixed to the flange (53) of the fixing tab (50).

10. The storage device (1) according to claim 1 or 2, wherein The pipe (30) is made of carbon steel and the pipe (30) is made of an iron-based alloy containing 0% < C < 2.11% by weight.

11. A storage device (1) according to claim 10, wherein The pipe (30) is made of a steel according to IGC specification A, B, D, AH, DH, EH, FH or E class.

12. The storage device (1) according to claim 1 or 2, wherein The upper cover wall (23) and the fixing tab (50) are made of an iron-based alloy comprising an austenitic steel containing 0 < C < 0.08%, 0% < Mn < 2%, 0% < Si < 0.5%, 0% < P < 0.045%, 0% < S < 0.030%, 8% < Ni < 14%, 16% < Cr < 50%, 0% < N < 0.02% by weight, the remainder being iron and unavoidable impurities resulting from the production of iron.

13. The storage device (1) according to claim 1 or 2, wherein The lower cover wall (22) comprises: - a plurality of planar metal sheets, assembled to each other, made of iron-nickel alloys with a coefficient of thermal expansion comprised between 0.5.10 -6 K -1 and 2.10 -6 K -1 or - a plurality of corrugated metal sheets juxtaposed in a repeating pattern and welded together in a sealed manner, the corrugated metal sheets being made of stainless steel.

14. A ship (70) for transporting a cold liquid product, the ship having a double hull (72) and a storage installation (1) according to one of claims 1 to 13 arranged in the double hull.

15. A delivery system for delivering a cold liquid product, the delivery system comprising: The ship (70) according to claim 14; an insulated pipe assembly (73, 79, 76, 81) arranged in such a way as to connect the sealed insulated tank (71) installed in the hull of the ship to a floating or onshore external storage installation (77); and a pump for transporting a flow of cold liquid product through the insulated pipe assembly from the floating or onshore external storage installation to the sealed insulated tank of the ship, or from the sealed insulated tank of the ship to the floating or onshore external storage installation.

16. A method for loading or unloading from a vessel (70) according to claim 14, wherein, Cold liquid product is transferred through an insulated pipe assembly (73, 79, 76, 81) from a floating or shore-based external storage facility (77) to the sealed, insulated tank of the vessel (70), or from the sealed, insulated tank of the vessel to a floating or shore-based external storage facility.

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