Liquid dome for storage tank of liquefied gas

Abstract

The invention relates to a storage installation (1) for liquefied gas and a sealed and insulated tank (71) having a loading / unloading opening (10), the sealed and insulated tank comprising a lower cover wall (23) having lateral closure strip portions (60, 61), each lateral closure strip portion having a plurality of stiffeners made of the same material as the material of the strip portion.

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 liquefied petroleum gas (also called GPL, Gaz de Pétrole Liquéfié) at a temperature between -50°C and 0°C, or tanks for transporting liquefied natural gas (GNL, Gaz Naturel Liquéfié) at about -162°C at atmospheric pressure. These tanks can also be installed on land or on a floating structure. In the case of a floating structure, the tanks can be intended to transport liquefied gas or to receive liquefied gas used as fuel for propelling the floating structure. BACKGROUND

[0002] Document FR 2 991 430 describes a storage equipment for liquefied gas, comprising a sealed and insulated tank, the insulated tank being integrated in 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, these various elements constituting the main structure of the liquefied gas storage tank.

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

[0004] The liquid dome is generally assembled independently of the tank, the tank having a real tank portion in the shape of a polyhedron and an opening intended to accommodate the liquid dome, the liquid dome generally being located at the rear end of the tank. This opening has a square or rectangular cross-section. As regards the opening intended to receive the liquid dome, the polyhedral tank forms the main structure and is provided with at least one metal sealing membrane and one insulating barrier (as described above). The main structure is manufactured as a storage equipment for liquefied gas of a structure, generally a ship, and the liquid dome is arranged to close the opening in the tank, while in particular enabling the passage of pipes for loading / unloading liquefied gas, as well as other access holes for operators (called "manholes") or for materials (called "material holes").

[0005] Since the liquid dome is assembled as a block essentially having its sealing membrane and its thermal barrier portion, it is necessary to connect the sealing membrane of the liquid dome to the sealing membrane of the body structure in a sealed manner. This connection operation can be achieved by using four side closure strips which are welded in a sealed manner between the sealing membrane of the liquid dome and the body structure. In Figures 2 to 4 The sequence of mounting / assembly of the liquid dome in / on the body structure of the tank of liquefied gas is shown in

[0006] However, after several tests and experiments, the Applicant has found that, once the liquid dome is mounted on the body structure of the storage installation, in particular due to the ballast condition of the ship, and / or when the ship is subjected to very high mechanical stresses due to severe environmental conditions (typically, significant phenomena of longitudinal bending along the axis of the ship), the risk of buckling of these side closure strips can occur, and cause cracks at the welds of the side closure strips, and thus at least partial loss of sealing.

[0007] Based on this analysis, the Applicant aims to remedy the possible weakness that tends to occur in this area by simply and effectively improving the mechanical integrity of these side closure strips, to ensure the sealed connection between the liquid dome and the body structure. SUMMARY

[0008] The present application therefore relates to a storage installation for liquefied gas, comprising a load-bearing structure and a sealed and thermally insulated tank arranged in the load-bearing structure; the sealed and thermally insulated tank has a body structure formed by a plurality of tank walls connected to each other and fastened to the load-bearing structure, the body structure defining an internal storage space, the body structure comprising at least one sealing membrane and at least one thermal barrier portion arranged between the sealing membrane and the load-bearing structure; the load-bearing structure has a substantially planar upper load-bearing wall; the sealing membrane and the thermal barrier portion of the body structure and the upper load-bearing wall are locally interrupted to delimit a loading / unloading opening intended to pass a fluid loading / unloading duct therethrough; wherein the tank has a cover portion arranged in the loading / unloading opening; wherein the cover portion comprises an upper cover wall, a lower cover wall and a thermal insulation structure located between the lower cover wall and the upper cover wall;

[0009] wherein the lower cover wall has a plurality of flat metal sheets joined to each other in a sealed manner, the plurality of flat metal sheets comprising at least one main partition and two side closure strips each intended to seal the lower cover wall to the body structure in a sealed manner and to connect the lower cover wall to the body structure.

[0010] The invention is characterized in that at least one of the side closure strip portions is adjacent to a structural insulation portion and in that said side closure strip portion has a plurality of stiffeners made of the same material as the material of said strip portion.

[0011] Thus, after numerous tests and analyses, the Applicant has observed that, due to the structure or operation of the ship, in particular in particularly harsh environmental conditions (in particular due to external cold, sea conditions and / or weather), these side closure strip portions can be subjected to mechanical constraints, for example the seal of the fastening welds of the side closure strip portions is prone to failure.

[0012] Based on these analyses, the Applicant proposes a simple, effective and low-cost system for completely sealing and protecting these specific areas. First of all, these adjacent side strip portions are arranged adjacent to a structural insulation portion, next these strip portions are mechanically fastened to this structural insulation portion at a plurality of points.

[0013] After numerous tests, the Applicant has been able to verify that this arrangement makes it possible to maintain the seal of the storage equipment for liquefied gas at these side closure strip portions, which are undoubtedly one of the most critical locations for a structure such as a ship in terms of mechanical stresses.

[0014] The expression "made of the same material" in relation to the stiffeners and the side closure strip portions means that both elements are metal and advantageously the same type of metal, for example two steels or alloys based on iron with similar or different grades.

[0015] The term "stiffener" means an element whose function is to stiffen or make rigid the side closure strip portion.

[0016] In the context of the invention, an insulation portion is said to be "structural" when it has mechanical strength and / or integrity properties, while an insulation portion is said to be "non-structural" when it does not have such mechanical properties.

[0017] Thus, in the context of the invention, the structural insulation portion can comprise a plywood box portion or a polymer foam, the density of which is at least equal to ninety (90) kilograms per cubic meter (kg·m -3 One of these two structural insulation portions (in the case where the box portion is made of plywood) is able to receive mechanical fastening means, while the other (in the case where the box portion is made of high-density polymer foam) does not have this capacity, or does not have this capacity in the best or preferred manner. By convention, the structural insulation portion able to receive or accommodate mechanical fastening portions is defined by the expression "mechanically structural insulation portion".

[0018] This is why, according to a particularly advantageous aspect of the application, the side closure strip is mechanically fastened to some or to adjacent mechanically structural insulating portions.

[0019] In the context of the application, the non-structural insulating portion can comprise a polymer foam or glass wool having a density lower than 90 kg.m -3 -4, such a foam being referred to as low-density polymer foam, preferably still a polyurethane foam.

[0020] By convention, the terms "external" and "internal" are used to define the relative position of one element with respect to another, with reference to the inside and outside of the tank.

[0021] Other advantageous features of the application are briefly explained below:

[0022] According to one possible embodiment provided by the application, the insulating structure of the lid portion comprises structural insulating portions and non-structural insulating portions.

[0023] Thus, in particular, it will be understood that the insulating box portion comprises structural portions (i.e. plywood) and non-structural portions (i.e. glass wool or low-density polymer foam contained in the structural portions).

[0024] According to one variant embodiment of the application, the insulating structure of the lid portion consists only of structural insulating portions. In this variant, the insulating structure of the lid portion can participate in maintaining or helping to maintain the seal of the storage installation for liquefied gas at one or more side closure strips according to the application.

[0025] Advantageously, the stiffener is fastened to the side closure strip by welding.

[0026] Preferably, the lower lid wall comprises the main partition and the side closure strip, the lower lid wall 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 , preferably of .

[0027] Preferably, the flat metal sheets of the lower lid wall, comprising at least the main partition and the side closure strip, are fastened to each other by welding.

[0028] Preferably, the side closure strip has a length of between 400 and 550 cm, preferably of between 440 and 510 cm, a width of between 20 and 40 cm, preferably of between 25 and 30 cm, and a thickness of between 1.2 and 1.8 mm.

[0029] In particular as can be seen in Figure 4 It is important to note that there are four side closing bars, which are intended to close and connect the lower wall of the cover in a sealed manner to the main structure, however, because according to the Applicant's analysis, the side closing bars extending along the axis x'x are subjected to the most severe mechanical stresses, in particular due to buckling caused by the compression of the ends of the bars resulting from the elongation of the hull girder, the present invention is intended in particular to be applied to the side closing bars extending along the axis x'x, which is perpendicular to the longitudinal axis of the ship. In the broadest definition of the invention, the present invention will be applied to at least one of the two side closing bars of the present invention extending along the axis x'x, very advantageously to both of them, but the present invention is explained below by considering the present invention applied to both of the side closing bars extending along the axis x'x.

[0030] Of course, it is also conceivable to apply the present invention to all four side closing bars, i.e. to the other two bars extending along the longitudinal axis of the ship.

[0031] According to a first preferred embodiment, the stiffener comprises a linear section welded to the side closing bar.

[0032] In the case of this first embodiment, preferably, the length of the stiffener is at least equal to the width of the side closing bar.

[0033] Still in this case, advantageously, the stiffener extends perpendicularly with respect to the axis x'x of the side bar, or extends along an oblique angle with respect to the axis x'x, the oblique angle being an angle comprised between 30° and 60°, preferably between 40° and 50°.

[0034] According to a second preferred embodiment, the side closing bar comprises a plurality of bar sections, each bar section having at least one edge strip at one end, the stiffener comprising the edge strips.

[0035] In the case of this second embodiment, preferably, the edge strips of two adjacent bar sections are welded to each other in a sealed manner.

[0036] Advantageously, the stiffener extends along a linear axis different from the linear axis of the edge strips of the adjacent sealing membrane of said main structure.

[0037] According to an advantageous embodiment, the thermally insulating structure of the cover and / or the structural thermally insulating part adjacent to the side closing bar comprises a plurality of boxes, preferably made of plywood, which are juxtaposed to each other and filled with a thermally insulating filler.

[0038] According to an advantageous embodiment, the non-structural thermally insulating part of the thermally insulating structure of the cover comprises at least one polymer foam, for example low density (less than or equal to 90 kg.m-3 ) block of polyurethane foam.

[0039] Advantageously, the sealing membrane is a primary sealing membrane, the thermal barrier portion is a primary thermal barrier portion, and wherein the main body structure of the tank comprises, in a thickness direction from the outside to the inside of the tank: a secondary thermal barrier portion, the secondary thermal barrier portion being fastened to the load-bearing structure; a secondary sealing membrane, the secondary sealing membrane being carried by the secondary thermal barrier portion; the primary thermal barrier portion, the primary thermal barrier portion being carried by the secondary sealing membrane; and the primary sealing membrane, the primary sealing membrane being carried by the primary thermal barrier portion, and intended to be in contact with the liquefied gas.

[0040] The invention more particularly relates to a vessel for transporting a cold liquid product, the vessel having a double hull and a storage installation as described above, the storage installation being arranged in the double hull.

[0041] Advantageously, the vessel has an inner wall panel and an outer wall panel, the inner upper load-bearing wall of the load-bearing structure being formed by the inner wall panel and the outer upper load-bearing wall being formed by the outer wall panel.

[0042] The invention also relates to a system for delivering a cold liquid product, the system having a vessel as described above, a thermal pipe arranged to connect a tank installed in the hull of the vessel to an external storage installation floating or on land, and a pump for delivering a flow of cold liquid product through the thermal pipe from the external storage installation floating or on land to the tank of the vessel or from the tank of the vessel to the external storage installation floating or on land.

[0043] Finally, the invention relates to a method for loading or unloading a vessel as described above, wherein a cold liquid product is supplied from an external storage installation floating or on land to a tank of the vessel or from a tank of the vessel to an external storage installation floating or on land through a thermal pipe. BRIEF DESCRIPTION OF DRAWINGS

[0044] The invention will be better understood and other objects, details, characteristics and advantages of the invention will become more clearly apparent from the following description of multiple specific embodiments, given by way of illustration and non-limiting examples, with reference to the attached drawings.

[0045] [ Figure 1 ] Figure 1 Schematic view of a cross section of a liquid dome according to a first or second embodiment of the invention.

[0046] [ Figure 2 ] Figure 2 First step of assembling a liquid dome is schematically shown, in which the cover portion of the liquid dome and the following portion of the main body structure are visible, into which the cover portion of the liquid dome is to be inserted and connected.

[0047] [ Figure 3 ] Figure 3 schematically illustrates a second step of assembling the liquid dome, following the sequence shown in Figure 2 , in which the cover portion of the liquid dome is inserted into the main body structure.

[0048] [ Figure 4 ] Figure 4 schematically illustrates a third step of assembling the liquid dome, following the sequence shown in Figure 2 and Figure 3 , in which four side closure strips are arranged with respect to the cover portion and are prepared to connect the cover portion to the main body structure in a sealed manner.

[0049] [ Figure 5 ] Figure 5 is a top view of a side closure strip according to a first embodiment of the application.

[0050] [ Figure 6 ] Figure 6 is a schematic view of a strip section forming a side closure strip according to a first embodiment of the application.

[0051] [ Figure 7 ] Figure 7 shows a region of a side closure strip according to the first embodiment in cross section.

[0052] [ Figure 8 ] Figure 8 is a top view of a side closure strip according to a second embodiment of the application.

[0053] [ Figure 9 ] Figure 9 shows a region of a side closure strip according to the second embodiment in cross section.

[0054] [ Figure 10 ] Figure 10 is a schematic view of some possible stiffeners according to the second embodiment of the application.

[0055] [ Figure 11 ] Figure 11 is a top view of a cover portion forming a liquid dome according to a variant of the second embodiment of the application, which cover portion has a side closure strip.

[0056] [ Figure 12 ] Figure 12 is a schematic sectional view of a storage installation of a methane tanker and of a distribution station of the tanker for loading / unloading. DETAILED DESCRIPTION

[0057] Herein, the term "vertical" means extending in the direction of the gravitational field of the Earth. Herein, the term "horizontal" means extending in a direction perpendicular to the vertical direction.

[0058] The present application is illustrated below with a ship. In fact, it is precisely in this type of structure, which houses storage plants according to the prior art, that the Applicant has been able to reveal potential defects and therefore to solve them through the present application. However, it is conceivable to apply the features of the present application to structures of different nature, for example structures of the storage type on land or at sea (known as "Global Base Storage, GBS").

[0059] Figure 1 A portion of the storage plant 1 at the liquid dome is schematically shown, which comprises a load-bearing structure 2. Inside the load-bearing structure 2, the storage plant 1 comprises a sealed and insulated tank 71, which will be described hereinafter.

[0060] The load-bearing structure 2 has a plurality of walls connected to each other, in particular an upper load-bearing wall 3, as can be seen in Figure 1 The upper load-bearing wall is located at the top of the storage plant 1.

[0061] When the storage plant 1 is positioned on a ship, such as a methane tanker, the load-bearing structure 2 is formed by the double hull of the ship. Therefore, the upper load-bearing wall 3 is referred to as the inner plating 3 of the ship, while there is also an outer plating, which is not visible in Figure 1

[0062] The tank 71 has a main structure formed by a bottom wall (not shown), a top wall 3 (upper wall or inner plating), two cofferdam walls 4 connecting the bottom wall to the top wall 3 and located at the front and rear of the storage plant 1, 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 3. Therefore, the walls of the tank 71 are connected to each other to form a polyhedral structure and delimit an internal storage space.

[0063] In order to load and unload liquefied gas into / from the tank 71, the storage plant 1 has a loading / unloading opening 10, which partially interrupts the top wall of the tank 71 to allow, in particular, loading / unloading pipes to pass through this opening 10 to reach the bottom of the tank 71, the pipes not being shown in the attached drawings. In particular, the apertures required by these pipes in the liquid dome are visible in Figure 2

[0064] ​​The storage installation 1 also comprises a loading / unloading tower, not shown in the figures, which is provided in correspondence with the opening 10 and which forms a support structure for the loading / unloading pipes (not visible in the figures) and for the pumps (not shown in the figures) over the entire height of the tank 71. It is important to note that this loading / unloading tower is engaged to the lid 12 of the liquid dome once the tank 71 has been arranged.

[0065] The storage installation 1 thus has a lid 12 which is arranged in the loading / unloading opening 10 to close the internal storage space at said opening 10. The lid 12 comprises an access hole which enables the loading / unloading pipes to pass through the lid 12, and two access through-holes having a greater diameter, one of which is called the operator access hole (or “manhole”) and the other of which is called the material access hole (or “material hole”), the access hole and the two access through-holes being visible in Figures 2 to 4 .

[0066] In the context of the present invention, this lid 12 also denotes a “liquid dome”. The loading / unloading opening 10 has a rectangular or square profile.

[0067] The tank 71 is a membrane tank which enables a liquefied gas to be stored. The main structure 6 of the tank 71 comprises a multilayer structure which has, from the outside in: a secondary thermal barrier portion having thermal insulation elements and which rests on the load-bearing structure 2, 3 or 4 in the figures; a secondary sealing membrane 17 which rests on the secondary thermal barrier portion 16; a main thermal barrier portion 18 having thermal insulation elements and which rests on the secondary sealing membrane 17; and a main sealing membrane 19 which is intended to come into contact with the liquefied gas in liquid or gaseous form which is contained in the tank 71.

[0068] According to one embodiment, the main structure of the tank 71 is manufactured according to the technology, which is described in particular in document FR-A-2867831. This document is incorporated by reference herein to describe the arrangement of the main structure 6, in particular the arrangement of the main structure at the elements 16, 17, 18 and 19.

[0069] The lid portion 12 has a multilayer structure with an upper lid wall 22, a lower lid wall 23 and a thermal insulation structure 24 arranged between the two walls 22, 23. The lower lid wall 23 has a plurality of flat metal sheets joined to each other in a sealed manner, including at least one main partition and two pairs of side closure strips 60, 61, which will be described in more detail below. The lower lid wall 23 thus forms the main sealing membrane of the lid portion 12; this is why the lower lid wall has to be connected to the main membrane 19 of the main body structure 6. As will be seen in more detail below, this connection is ensured by the side closure strips 60, 61. The upper lid wall 22 is fastened in a sealed manner to the inner wall sheet 3 that completely surrounds the opening 10, so that the upper lid wall 22 acts as a secondary sealing membrane 17. The upper lid wall 22 is made using a metal material, for example stainless steel.

[0070] The thermal insulation structure 24 comprises a plurality of thermal insulation elements, which are juxtaposed to each other and can have similar or different structures. The plurality of thermal insulation elements can be so-called "structural" thermal insulation elements 40, which intrinsically have better or even much better mechanical integrity features or properties than so-called "non-structural" thermal insulation elements 41. The structural thermal insulation elements 40 can be high-density polymer foam blocks optionally reinforced with fibers, or boxes made of plywood or composite material filled with thermal insulation filler, which is intrinsically a non-structural thermal insulation, for example glass wool, polymer foam or perlite. The non-structural thermal insulation elements 41 can be low-density polymer foam blocks or glass wool blocks. The words "structural thermal insulation element" and "non-structural thermal insulation element" refer to both types of elements 40, 41 having, in addition to their existing thermal insulation properties, the mechanical properties described above.

[0071] Figures 2 to 4 The sequence of installation and assembly of the lid portion 12 in the opening 10 is shown. As can be observed in Figure 2 and Figure 3 The lid portion 12 has approximately the same dimensions as the opening 10. Once the lid portion 12 has been arranged in place in the opening 10, the four side closure strips 60, 61 are positioned to ensure the sealed connection between the lid portion 12 and the main sealing membrane 19 of the main body structure 6, more specifically the lower lid wall 23.

[0072] Advantageously, the main sealing membrane 19 of the main body structure 6, the side closure strips 60, 61 and the lower lid wall 23 are all made of a single material, for example , which has a very low coefficient of thermal expansion. The same metal alloy nature of the three elements 23, 19 and 60, 61 makes it easier to connect them in a sealed manner by welding.

[0073] Two of the four side closing strip portions, i.e. the strip portions 61, extend along the longitudinal axis of the boat, while the other two side closing strip portions 60 extend along an axis x'x perpendicular to the longitudinal axis of the boat. As mentioned above, the Applicant has found that the strip portions 60 are more susceptible to more severe buckling than the strip portions 61, which is why the present application is first intended to be implemented for at least one of these strip portions 60, ideally for both of these strip portions 60. The present application is illustrated below with a single strip portion 60, however it is advantageous and even ideal that the present application is applied to both strip portions 60, or even to the other two strip portions 61, in the case where the present application does not need to be applied to the other two strip portions 61.

[0074] Figures 5 to 7 A first embodiment of the present application is illustrated, in which the closing strip portion 60 is composed of or comprises a plurality of strip portions 65, 65', 65", advantageously each of which does not have the same length and thickness, as a function of the arrangement of the thermal insulation structure 24 fastened to the lower cover wall 23 for one of the strip portions, and of the arrangement of the main body structure 6 fastened to the main sealing membrane 19 for the other strip portion, the respective lengths of the strip portions possibly being equal or different. Thus, each of these strip portions 65, 65', 65" has a fillet 67, 67' or 67" (i.e. a bend forming a substantially L-shaped end portion) at at least one of the longitudinal ends of each of the strip portions, i.e. along the extension axis x'x, the fillet being welded at its base to the contiguous strip portion 65, 65' or 65" without a fillet at the end of the strip portion. However, advantageously, both ends of each of the strip portions 65, 65', 65" have such a fillet 67, 67' or 67", so that the adjacent ends of two contiguous strip portions 65, 65' or 65', 65" are fastened together by the respective fillets 67, 67' or 67" of the strip portions.

[0075] Thus, regardless of whether each of the strip portions 65, 65', 65" has one or two fillets 67, 67' or 67" at the two longitudinal ends of the strip portion, the connection between two strip portions 65, 65', 65" is sealed, and these fillets 67, 67' or 67" also serve as reinforcement of the side closing strip portion 60.

[0076] In Figure 5 and Figure 6 It can be seen that, according to one possible implementation provided by the present application, the side closing strip portion 61 or an end portion of the side closing strip portion 61 comprises a fillet at its end adjacent to the closing strip portion 60, the fillet being fastened to the strip portion 65 in a sealed manner, advantageously by the fillet 67 or 67' of the strip portion forming part of the side closing strip portion 60.

[0077] It is important to note that, in the Figure 7 It can be noted that the edge strips 67, 67' or 67" of the strip portions 65, 65' or 65" are identical in shape and size (thickness and height or degree of protrusion with respect to the strip portion 60 or film 19 from which they originate) to the edge strips of the main structure 6, i.e. originating from the main film 19. It can also be noted that each of these edge strips 67, 67' or 67" extends along a linear axis which is identical to or extends the linear axis of each edge strip of the adjacent main film 19 of the main structure 6. However, in the Figure 7 variant, advantageously, each of these edge strips 67, 67' or 67" can also extend along a linear axis which is different from, i.e. offset from, the linear axis of each edge strip of the adjacent main film 19 of the main structure 6, for example as shown in Figure 8 by the reinforcement 90 in the

[0078] Thus, in this first embodiment, each edge strip 67, 67' or 67" of the side closure strip portion 60 constitutes a means for making a sealed connection between the various strip portions 65, 65', 65" forming the side closure strip portion 60 and a reinforcement having the function of preventing or impeding any buckling of the side closure strip portion 60.

[0079] It is understood here that, in the context of the application, when reference is made to a sealed coupling or a sealed connection, an advantageous embodiment of this coupling / connection comprises welding.

[0080] Figures 8 to 11 A second embodiment of the application is shown, in which the reinforcement is not constituted by an element originating from the side closure strip portion 60 or from the various portions 65, 65', 65" forming the side closure strip portion 60, but is an independent metal element 90 which is advantageously fastened to the side closure strip portion 60 by welding.

[0081] These reinforcements 90 are constituted by a metal part which advantageously extends linearly and can have a variable profile section, as shown in Figure 10 Thus, by way of example, the reinforcement 90 can have a section 90' shaped like an L, a joined double L section 90" or an I section 90'". These reinforcements 90 are welded 100 to the side closure strip portion 60 in a sealed manner at the base 91 of the reinforcement, it being possible of course to arrange on the strip portion 60 reinforcements having a different section profile, in particular for example in Figure 10The stiffeners 90 of the cross sections 90', 90" and 90"') illustrated in

[0082] In Figure 8 It can be seen in that, according to one possible embodiment provided by the application, the stiffeners 90 extend perpendicularly to the axis x'x of the side closure strip portion 60, in other words, these stiffeners 90 extend along the longitudinal axis of the marine vessel, like the stringers present on the adjacent main films 19 of the body structure 6 of the tank 71. It should also be noted that, advantageously, the stiffeners 90 are offset with respect to the linear axis of the stringers of the main films 19 of the body structure and are positioned substantially midway between the two parallel linear axes of two adjacent stringers of the main films 19. This arrangement of the stiffeners is referred to as "staggered" with respect to the stringers of the main films 19 of the body structure 6, this arrangement of the stiffeners 90 making it possible to provide better mechanical integrity of the side closure strip portion 60, in particular to combat the risk of buckling.

[0083] According to another advantageous possible embodiment illustrated in Figure 11 In this arrangement, the stiffeners 90 are advantageously arranged in a quasi- contiguous manner, by alternately reversing the angle of two contiguous stiffeners 90 with respect to the axis x'x. This arrangement also makes it possible to improve the mechanical function of the stiffeners 90 on the side closure strip portion 60.

[0084] In all the embodiments of the application, as the Applicant has discovered, it is necessary to arrange the structural insulation portion 40 adjacent or contiguous to the side strip portion 60, so that this structural insulation portion 40 contributes to the mechanical integrity of the strip portion 60. Of course, the stiffeners 67, 90 provide most of the mechanical strength and integrity of the side closure strip portion 60, in particular against buckling, however this structural insulation portion 40 acts in synergy with the stiffeners 67, 90 to ensure the mechanical integrity of the strip portion 60.

[0085] Figure 12An example of an offshore terminal is shown having a loading and unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and unloading station 75 is a fixed offshore facility having 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 the loading / unloading pipeline 73. The orientable mobile arm 74 is suitable for all sizes of methane tanker. Connection pipelines (not shown) extend within the tower 78. The loading and unloading station 75 enables loading of a methane tanker 70 from the onshore installation 77 or unloading of a methane tanker onto the onshore installation. The onshore installation has liquefied gas storage tanks 80 and connection pipelines 81 which are connected to the loading and unloading station 75 by the underwater pipeline 76. The underwater pipeline 76 enables transport of liquefied gas between the loading and unloading station 75 and the onshore installation 77 over a long distance, for example 5 km, and this enables the methane tanker 70 to remain at a long distance from the coast during the loading and unloading operations.

[0086] To generate the pressure required to transport the liquefied gas, use is made of pumps on board the vessel 70 and / or pumps equipped to the onshore installation 77 and / or pumps equipped to the loading and unloading station 75.

[0087] Although the application has been described in relation to a number of particular embodiments, it will be apparent that the application is not limited to the details described and that the application includes all technical equivalents of the described devices and combinations of technical equivalents.

[0088] The verb "comprise", "comprising" or "comprises" and its conjugations does not exclude the presence of elements or steps other than those stated in the claim.

[0089] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A storage device (1) for liquefied gas, comprising a support structure (2) and a sealed and insulated tank (71) arranged in the support structure (2); The sealed and insulated tank (71) has a main structure (6) formed by a plurality of tank walls connected to each other and fastened to the support structure (2), the main structure (6) defining an internal storage space, the main structure (6) including at least one sealing membrane and at least one heat insulation barrier portion disposed between the sealing membrane and the support structure (2). The load-bearing structure (2) has a generally flat upper load-bearing wall (3); The sealing membrane and the heat insulation barrier portion of the main structure (6) and the upper bearing wall (3) are partially interrupted to define a loading / unloading opening (10) designed to allow fluid loading / unloading pipes to pass through the loading / unloading opening; in, The tank (71) has a cover (12) arranged in the loading / unloading opening (10); The cover (12) includes an upper cover wall (22), a lower cover wall (23), and a heat insulation structure (24), wherein the heat insulation structure is located between the lower cover wall (23) and the upper cover wall (22); The lower cover wall (23) has a plurality of flat metal plates joined together in a sealing manner. The plurality of flat metal plates include at least one main partition and two side sealing strips, each of which is designed to seal the lower cover wall (23) to the main structure (6) and to connect the lower cover wall to the main structure. The feature is that at least one of the side closure strips is adjacent to the structural heat insulation part (40), and the side closure strip has a plurality of reinforcing members made of the same material as the side closure strip.

2. The storage device (1) according to claim 1, wherein, The reinforcing member is fastened to the side closure strip by welding.

3. The storage device (1) according to claim 1 or 2, wherein, The lower cover wall (23), including the main partition and the side sealing strip, is made of material with a thermal expansion coefficient between 0.5 and 10. -6 K -1 Up to 2.10 -6 K -1 It is made of an iron-nickel alloy.

4. The storage device (1) according to claim 1 or 2, wherein, The flat metal plates of the lower cover wall (23), including at least the main partition and the side closure strip, are fastened to each other by welding.

5. The storage device (1) according to claim 1 or 2, wherein, The length of the side closure strip is between 400 cm and 550 cm, the width of the side closure strip is between 20 cm and 40 cm, and the thickness of the side closure strip is between 1.2 mm and 1.8 mm.

6. The storage device (1) according to claim 1 or 2, wherein, The reinforcing member includes a linear section welded to the side closure strip.

7. The storage device (1) according to claim 6, wherein, The length of the reinforcing member is at least equal to the width of the side closure strip.

8. The storage device (1) according to claim 1 or 2, wherein, The reinforcing member extends perpendicularly to the axis x'x of the side closure strip, or extends along an angle of inclination relative to the axis x'x, the angle being between 30° and 60°.

9. The storage device (1) according to claim 1 or 2, wherein, The side closure strip includes a plurality of strip segments (65, 65', 65"), each strip segment (65, 65', 65") having at least one side strip (67, 67', 67") at one end, and the reinforcement includes the side strip (67, 67', 67").

10. The storage device (1) according to claim 9, wherein, The side strips (67, 67', 67") of two adjacent strip segments (65, 65', 65") are welded to each other in a sealed manner.

11. The storage device (1) according to claim 1 or 2, wherein, The reinforcing member extends along a linear axis that is different from the linear axis of the edge strip of the adjacent sealing membrane of the main structure (6).

12. The storage device (1) according to claim 1 or 2, wherein, The heat insulation structure (24) of the cover (12) and / or the structural heat insulation part (40) adjacent to the side sealing strip includes a plurality of box parts, which are arranged side by side and filled with heat insulation filler.

13. The storage device (1) according to claim 1 or 2, wherein, The non-structural insulation portion (41) of the insulation structure (24) of the cover (12) includes at least one polymer foam block.

14. The storage device (1) according to claim 1 or 2, wherein, The sealing membrane is the main sealing membrane, the heat insulation barrier is the main heat insulation barrier, and wherein the main structure (6) of the tank (71) includes, in the thickness direction from the outside to the inside of the tank (71): a secondary heat insulation barrier, the secondary heat insulation barrier being fastened to the supporting structure; a secondary sealing membrane, the secondary sealing membrane being supported by the secondary heat insulation barrier; a main heat insulation barrier, the main heat insulation barrier being supported by the secondary sealing membrane; and a main sealing membrane, the main sealing membrane being supported by the main heat insulation barrier and intended to contact the liquefied gas.

15. The storage device (1) according to claim 3, wherein, The lower cover wall (23) is made of Made.

16. The storage device (1) according to claim 12, wherein, The multiple box sections are made of plywood.

17. 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 16, the storage device being arranged in the double hull.

18. The vessel (70) according to claim 17, wherein, The vessel (70) has an inner wall panel (4) and an outer wall panel (5), the inner upper bearing wall of the bearing structure is formed by the inner wall panel (4), and the outer upper bearing wall is formed by the outer wall panel (5).

19. A system for conveying cold liquid products, the system comprising a vessel (70) according to claim 17 or claim 18, insulated pipes (73, 79, 76, 81), and a pump, the insulated pipes being arranged to connect the tank (71) installed in the hull of the vessel 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 pipes.

20. A method for loading or unloading a vessel (70) according to claim 17 or claim 18, wherein, Cold liquid products are supplied from a floating or land-based external storage unit (77) to the vessel's tank (71) or from the vessel's tank to a floating or land-based external storage unit via insulated pipes (73, 79, 76, 81).

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