Waterproof and thermally insulating tank

Abstract

The invention relates to a tank comprising a first wall which comprises, from the outside to the inside of the tank, a secondary insulating barrier (20), a secondary waterproof membrane (11), a primary insulating barrier (30) and a primary waterproof membrane (12), the secondary insulating barrier comprises a secondary corner insulating panel (21) which runs along the edge and which is adjacent to the edge, the secondary corner insulating panel comprises an insulating foam block (23) sandwiched between a bottom plate (24) and cover plates (25) each located opposite the bottom plate, the cover plates being spaced from each other by relaxation slots which develop in a thickness direction (E) of the insulating foam block and in a direction transverse (Y) to the edge, the relaxation slots have a depth of at least half the thickness of the insulating foam block. Figure for abstract: 2

Description

Title of the invention: Sealed and thermally insulating tank Technical field

[0001] The invention relates to the field of sealed and thermally insulating membrane tanks. In particular, the invention relates to the field of sealed and thermally insulating tanks for the storage and / or transport of liquefied gas at low temperature, such as tanks for the transport of Liquefied Natural Gas (LNG) at approximately -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank can be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the floating structure. Technological background

[0002] Known from the prior art is a sealed and thermally insulating tank with membranes integrated into a supporting structure. The tank successively comprises, in a thickness direction of the tank, a secondary insulation barrier, a secondary sealed membrane, a primary insulation barrier and a primary sealed membrane. At a corner of such a tank, the secondary insulation barrier comprises secondary corner insulation panels arranged along the edge.

[0003] Nevertheless, these secondary corner insulating panels, which are panels with small dimensions, are installed individually, one after the other, by one or more operators during assembly. Consequently, such assembly is long to carry out and involves a very large number of operators. In addition, the individual installation of each panel can cause positioning shifts of the secondary thermally insulating panels relative to each other, both in the longitudinal direction of the tank and in its transverse direction. Such shifts are likely to lead to premature damage to the secondary membrane of the tank and to a reduction in the final properties of the tank. Summary of the invention

[0004] The inventors have observed during confidential tests that increasing the dimensions of the secondary corner insulating panels in a tank creates additional thermodynamic problems. Indeed, when the tank is loaded with liquefied gas, that is to say when the tank is cooled, the secondary waterproof membrane and the secondary corner insulating panels contract under the effect of temperature changes. The elements that make up the tank and in particular the secondary waterproof membrane and the secondary insulating panels corner do not have the same coefficient of thermal expansion and therefore do not exhibit the same thermodynamic behavior in response to these temperature changes, which generates significant stresses in the secondary corner insulating panels as well as in the secondary waterproof membrane. Such stresses are likely to prematurely damage the tank. Thus, the inventors have found that the size of the secondary corner insulating panels in relation to the number and position of the secondary membrane anchors carried by the secondary insulating panels is important to minimize mechanical stresses and avoid premature damage to the tank.

[0005] One idea behind the invention is to provide a tank that solves the aforementioned problems.

[0006] One idea underlying the invention is to provide a tank comprising a thermally insulating barrier comprising secondary corner insulating panels allowing rapid and reliable manufacture of the tank.

[0007] An idea underlying the invention is to provide a tank with a thermally insulating barrier comprising secondary corner insulating panels making it possible to obtain a tank particularly suited to significant temperature changes, at the interface between the secondary corner insulating panels and the secondary waterproof membrane.

[0008] According to one embodiment, the invention provides a sealed and thermally insulating tank for the storage and / or transport of liquefied gas, the tank comprising a first tank wall fixed to a first load-bearing wall of a load-bearing structure and a second tank wall fixed to a second load-bearing wall of the load-bearing structure, the second load-bearing wall joining the first load-bearing wall at an edge of the load-bearing structure, in which the first tank wall comprises a multi-layer structure comprising from the outside to the inside of the tank, a secondary thermally insulating barrier anchored against the load-bearing structure, a secondary sealed membrane which is carried by the secondary thermally insulating barrier, a primary thermally insulating barrier and a primary sealed membrane which is carried by the primary thermally insulating barrier and which is intended to be in contact with the liquefied gas contained in the tank,wherein the secondary thermally insulating barrier comprises a secondary corner insulating panel which runs along the edge and is adjacent to the edge, the secondary corner insulating panel comprises an insulating foam block sandwiched between a base plate and cover plates each located opposite the base plate, the cover plates being spaced apart from each other, by relaxation slots which develop along a thickness direction of the insulating foam block and along a direction transverse to the edge, wherein the relaxation slots have a depth of at least half the thickness of the insulating foam block.

[0009] Thanks to these characteristics, the tank has excellent thermodynamic properties. Indeed, such an arrangement, thanks in particular to the presence of the relaxation slots, makes it possible to increase the flexibility of the secondary corner insulating panel. Consequently, the stresses exerted in the corner of the secondary membrane at the level of the secondary corner insulating panel and the secondary membrane are reduced and better distributed. Thus, the elements of the tank located at the interface between the secondary corner insulating panel and the secondary waterproof membrane are better preserved than in a tank not comprising such a secondary corner insulating panel.

[0010] According to embodiments, such a tank may comprise one or more of the following characteristics.

[0011] According to one embodiment, the secondary corner insulating panel comprises at least three cover plates.

[0012] According to one embodiment, the secondary insulating panel comprises exactly three cover plates.

[0013] According to one embodiment, the relaxation slots extend over at least 60% of the thickness of the insulating foam block, for example at least 70%, and preferably over at least 80% of the thickness of the insulating foam block. According to one embodiment, the relaxation slots extend over at least a thickness of 90%, 95% or 99% of the insulating foam block.

[0014] According to one embodiment, the relaxation slots extend over the entire thickness of the insulating foam block, up to the bottom plate.

[0015] According to one embodiment, the relaxation slots extend in a direction transverse to the edge, over the entire foam block.

[0016] According to one embodiment, the relaxation slots separate the foam block into three distinct portions which are spaced from each other by the relaxation slots.

[0017] According to one embodiment, the depth of the relaxation slots is identical.

[0018] According to one embodiment, the relaxation slots have a width between 0.1mm and 30mm. The thickness of a relaxation slot corresponds to the distance between two surfaces of the foam block facing each other which are formed by the relaxation slot. According to a first embodiment variant, the relaxation slots have a width between 0.1mm and 5mm. According to a second embodiment variant, the relaxation slots have a width between 10mm and 30mm, for example 20mm, which allows the placement of material in said slots.

[0019] According to one embodiment, the insulating foam block has n internal faces spaced from each other by the relaxation slots, and in which the secondary corner insulating panel comprises n cover plates each covering one of said internal faces; with n: an integer, preferably between 2 and 10, for example n = 3.

[0020] According to one embodiment, the insulating foam block has internal faces spaced from each other by the relaxation slots, in which the internal faces are each covered by a cover plate.

[0021] According to one embodiment, the secondary corner insulating panel comprises at least one insulating joint which is housed in one of the relaxation slots.

[0022] Thus, the convection phenomena in the relaxation slot are reduced.

[0023] According to one embodiment, the insulating seal fills the entire relaxation gap.

[0024] According to one embodiment, the secondary corner insulating panel comprises an insulating seal in each relaxation slot.

[0025] According to one embodiment, the insulating seal is a flat element.

[0026] According to one embodiment, the insulating seal is made of an elastically compressible.

[0027] According to one embodiment, the insulating joint is made of a material chosen from glass wool, rock wool and polyester wadding, synthetic foams for example polyurethane.

[0028] According to one embodiment, the insulating seal comprises one or more elements chosen from: cardboard, corrugated paper, a hard wood-based fiber board, a board of expanded or non-expanded polyethylene or propylene or polyurethane.

[0029] According to one embodiment, the secondary corner insulating panel comprises a first anchoring well and a second anchoring well which pass through a thickness of the secondary corner insulating panel, the first anchoring well passes through the cover plate which is located at a first end of the secondary corner insulating panel, and the second anchoring well passes through the cover plate which is located at a second end of the secondary corner insulating panel, and comprising first and second wall anchoring devices each comprising an external portion fixed to the supporting structure and an internal portion respectively located in the first and second anchoring wells and fixing the secondary corner insulating panel to the supporting structure.

[0030] The second end of the secondary corner insulation panel is located opposite the first end of the secondary corner insulation panel.

[0031] According to one embodiment, the first anchoring well and the second anchoring well pass through the thickness of the secondary corner insulating panel in the thickness direction of the secondary corner insulating panel.

[0032] According to one embodiment, the secondary corner insulating panel comprises a pair of anchoring wells, per cover plate, each of the anchoring wells of said pair passing through a thickness of the secondary corner insulating panel.

[0033] According to one embodiment, the secondary corner insulating panel comprises thermally insulating lining in each anchor well. According to one embodiment, the thermally insulating lining fills each anchor well. According to one embodiment, the thermally insulating lining is chosen from: glass wool, rock wool, polyester wadding, polystyrene, which may be expanded polystyrene (EPS), polyurethane foam (PU) which may be reinforced and which may comprise fibers.

[0034] According to one embodiment, the secondary corner insulating panel comprises only the first anchoring well which passes through the cover plate which is located at a first end of the secondary corner insulating panel, and the second anchoring well which passes through the cover plate which is located at a second end of the secondary corner insulating panel.

[0035] Thus, there are no additional anchoring wells located between the first anchoring well and the second anchoring well. As a result, thermal bridges are reduced and therefore the corner secondary insulating panel has better thermal insulation than a corner secondary insulating panel comprising a greater number of anchoring wells. In addition, when sealant beads on an external surface of the base plate are necessary, the installation of the sealant beads is facilitated and less restrictive. Indeed, the fewer anchoring wells there are, the less the sealant beads will have to be interrupted at said anchoring wells. Another consequence is that it is faster to install the secondary insulating panel because it has fewer anchors for implementation on the secondary insulating panel than in the case of a multitude of smaller secondary insulating panels.

[0036] According to one embodiment, the secondary corner insulating panel comprises metal plates which are each fixed to the insulating foam block, the metal plates each being located in a recess formed in one of the cover plates, the metal plates being flush with an internal face of the cover plate.

[0037] According to one embodiment, the secondary corner insulating panel comprises metal plates which are each fixed to one of the cover plates. According to one embodiment, the metal plates each comprise a first bore threaded. According to one embodiment, threaded studs anchor primary corner thermally insulating panels of the primary thermally insulating barrier to the secondary corner insulating panel. According to one embodiment, the threaded studs comprise a through portion which comprises a collar and which passes in a sealed manner through the secondary waterproof membrane; a first end which is fixed in the first threaded bore retaining the collar against the secondary waterproof membrane at the level of the metal plate and a second end which is equipped with a support member retaining the primary corner thermally insulating panel to the secondary corner insulating panel. According to one embodiment, the secondary waterproof membrane is welded to said metal plates around the threaded studs.

[0038] Thanks to these characteristics, the thermodynamic constraints are better distributed, in particular the mechanical stresses at the welds of the threaded studs are reduced, which increases the service life of the tank.

[0039] According to one embodiment, at least one of the threaded studs comprises a collar extending radially relative to the longitudinal axis of said stud.

[0040] According to one embodiment, the threaded studs comprise a collar extending radially relative to the longitudinal axis of the stud.

[0041] According to one embodiment, the metal plates each comprise a second tapped bore spaced from the first tapped bore.

[0042] According to one embodiment, threaded studs comprise a first end which is fixed in the second tapped bore, a through portion which passes in a sealed manner through the secondary waterproof membrane and a second end which is equipped with a support member retaining the primary thermally insulating corner panel to the secondary insulating corner panel.

[0043] According to one embodiment, the secondary corner insulating panel comprises a metal plate fixed to each cover plate.

[0044] According to one embodiment, the two anchoring wells of each pair of anchoring wells are arranged on either side of the metal plate.

[0045] According to one embodiment, the metal plates are located in the center of the cover plates.

[0046] Thanks to this arrangement, the movement of the metal plates linked to thermal contraction / expansion phenomena is reduced. Thus, the constraints are reduced in this area.

[0047] According to one embodiment, the secondary waterproof membrane comprises metal strakes comprising a flat portion resting on an upper surface of the secondary insulating barrier, at least one corrugation and two edges, the strakes being juxtaposed with each other and welded together in a watertight manner at the edges, in which the secondary waterproof membrane comprises a metal corner strip comprising a portion welded to an adjacent metal strake and a portion welded to each of the metal plates of the secondary corner insulating panel.

[0048] According to one embodiment, the secondary waterproof membrane comprises metal strakes comprising a flat portion resting on an upper surface of the secondary insulating barrier and two raised edges projecting towards the inside of the tank relative to the central portion, the strakes being juxtaposed and welded together in a sealed manner at the raised edges. According to one embodiment, the secondary waterproof membrane comprises a corner metal strip comprising a portion welded to an adjacent metal strake and a portion welded to each of the metal plates of the corner secondary insulating panel.

[0049] Thanks to these characteristics, the thermodynamic constraints are better distributed, in particular the mechanical stresses at the welds of the threaded studs are reduced, which further increases the service life of the tank.

[0050] Such an arrangement presents a synergy in particular via the relaxation slots, the metal plates, the metal corner strip and the strakes. Indeed, when filling the tank with liquefied gas, a thermal contraction effect is undergone by the secondary corner insulating panel, which modifies the distance between the metal anchor plates which are housed in the cover plates. Such thermal contraction is therefore reflected on and the metal strakes of the secondary waterproof membrane which has the consequence of mechanically stressing the sealing welds of the secondary waterproof membrane at the level of the threaded studs. However, thanks to the aforementioned characteristics, the mechanical stresses on the sealing welds are less, which increases the service life of the tank, particularly that of the secondary waterproof membrane at the level of the welds formed around the threaded studs.

[0051] According to one embodiment, the metal corner strip is welded to the metal strake, over the entire length of the metal corner strip.

[0052] Thus, the advantages of such a tank are increased because the thermal stresses on the corner metal strip at the welds are further reduced in comparison with a tank not comprising such a secondary corner panel.

[0053] According to one embodiment, the relaxation slits develop in a direction orthogonal to the edge.

[0054] According to one embodiment, the primary waterproof membrane is a corrugated metal membrane.

[0055] According to one embodiment, the primary waterproof membrane comprises a first series of undulations having first undulations parallel to each other and a second series of undulations having second undulations parallel to each other and perpendicular to the first undulations.

[0056] According to one embodiment, the primary waterproof membrane comprises a plurality of flat zones which are each defined between two adjacent first corrugations and between two adjacent second corrugations.

[0057] According to one embodiment, the secondary waterproof membrane is made of Invar®, that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.106 and 2.106 K ', or in an alloy of iron with manganese whose coefficient of expansion is typically between 7.106 and 9.106 K1.

[0058] According to one embodiment, the cover plates and the bottom plate are rigid. According to one embodiment, the cover plates and the bottom plate are made of plywood.

[0059] According to one embodiment, the secondary corner insulating panel comprises beads of mastic positioned against an external surface of the bottom plate.

[0060] According to one embodiment, the mastic beads are not positioned at the anchoring wells.

[0061] According to one embodiment, the secondary corner insulating panel has the following dimensions: - A length between 640 and 3400 mm; preferably 660 mm, 1000 mm or 3040 mm, - A width between 280 and 530 mm, for example 300 mm in the Y direction; and - A height between 250 and 400 mm, for example 300 mm. The length of the secondary thermally insulating barrier corner secondary insulation panel extends along the edge direction.

[0062] The dimensions of the secondary corner insulation panel must be considered with a tolerance of ± 20 mm.

[0063] Thus, these are secondary corner insulating panels with larger dimensions than in the prior art. Consequently, a smaller number of secondary corner insulating panels is required. Thus, the construction of the tank is accelerated and facilitated. In addition, when it is necessary to position beads of mastic, installation is facilitated and accelerated because the beads of mastic need to be applied to a smaller number of panel base plates. secondary corner insulators. According to one embodiment, the first tank wall comprises a plurality of aforementioned secondary corner insulating panels.

[0064] According to embodiments, the second tank wall has one, several or all of the characteristics of the first tank wall.

[0065] According to one embodiment, the first and second tank walls have the same aforementioned characteristics.

[0066] According to one embodiment, the secondary waterproof membrane of the second tank wall comprises metal strakes comprising a flat portion resting on an upper surface of the secondary insulating barrier and two raised edges projecting towards the inside of the tank relative to the central portion, the strakes being juxtaposed and welded together in a sealed manner at the raised edges, in which the secondary waterproof membrane of the second tank wall comprises a metal corner strip comprising a portion welded to an adjacent metal strake and a portion welded to each of the metal plates of the secondary corner insulating panel, in which the metal corner strips of the first and second walls meet at an edge and form a metal angle iron.

[0067] According to one embodiment, the metal angle iron forms an angle between 80° and 145°, preferably the angle is 90° or 135°.

[0068] According to one embodiment, the angle formed by the intersection between the first load-bearing wall and the second load-bearing wall is between 80° and 145°, preferably the angle is 90° or 135°.

[0069] In one embodiment, the liquefied gas is LNG, namely a mixture with a high methane content stored at a temperature of approximately -162°C at atmospheric pressure. Other liquefied gases may also be considered, in particular ethane, propane, butane or ethylene. Liquefied gases may also be stored under pressure, for example at a relative pressure of between 2 and 20 bar, and in particular at a relative pressure of around 2 bar. The tank may be produced using different techniques, in particular in the form of an integrated membrane tank or a self-supporting tank.

[0070] Such a tank may be part of a land-based storage facility, for example for storing LNG, or may be installed in a floating, coastal, or deep-water structure, including an LNG carrier, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO), and others. Such a tank may also serve as a fuel tank in any type of vessel.

[0071] According to one embodiment, a ship for transporting a liquefied gas comprises a double hull and a aforementioned tank, the double hull comprising the supporting structure.

[0072] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned ship, insulated pipes arranged to connect the tank installed in the hull of the ship to a floating or land-based storage facility and a pump for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the tank of the ship.

[0073] According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the ship's tank. Brief description of the figures

[0074] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings.

[0075] [Fig.l] represents a cutaway and schematic perspective view of a supporting structure intended to support a sealed and thermally insulating tank for storing a liquefied gas.

[0076] [Fig.2] illustrates a sectional view of a corner of a sealed and thermally insulating tank.

[0077] [Fig.3] illustrates a perspective view of a secondary corner insulating panel according to a first embodiment.

[0078] [Fig.4] illustrates a perspective view of a secondary corner insulating panel according to a second embodiment.

[0079] [Fig.5] is a cutaway schematic representation of a LNG carrier tank and a loading / unloading terminal for this tank.

[0080] [Fig.6] illustrates a device for anchoring primary panels which also provides a function for anchoring the strakes. Description of the embodiments

[0081] 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.

[0082] A supporting structure 1 intended to support a sealed and thermally insulating tank for storing a liquefied gas is shown in [Fig.l]. The structure The load-bearing structure 1 may in particular be formed from self-supporting metal sheets or, more generally, from any type of rigid partition having appropriate mechanical properties. The load-bearing structure 1 is, for example, formed by the double hull of a ship. In [Fig.l], the load-bearing structure 1 has a generally polyhedral shape. It has two front and rear load-bearing walls 2, here octagonal in shape, of which only the rear load-bearing wall 2 is shown. The front and rear walls 2 are, for example, cofferdam walls of the ship which extend transversely to the longitudinal direction of the ship. The load-bearing structure 1 also comprises an upper load-bearing wall 3, a lower load-bearing wall 4 and side load-bearing walls 5, 6, 7, 8, 9, 10.

[0083] Illustrated in [Fig. 2] is an angle of a membrane tank for storing liquefied gas. The tank has a first tank wall fixed to a first load-bearing wall 104 of a load-bearing structure 101 and a second tank wall fixed to a second load-bearing wall 107 of the load-bearing structure 101, the second load-bearing wall 107 joining the first load-bearing wall 104 at an edge of the load-bearing structure 101, forming an angle of approximately 135° in the embodiment shown.

[0084] The first tank wall and the second tank wall each have a multi-layer structure comprising, at the angle, from the outside to the inside of the tank: - a secondary thermally insulating barrier 20 resting against the supporting structure 101, - a secondary waterproof membrane 11 resting against the secondary thermally insulating barrier 20, - a primary thermally insulating barrier 30 which rests against the secondary waterproof membrane 11, and - a primary waterproof membrane 12 intended to be in contact with the liquefied gas contained in the tank.

[0085] The primary sealed membrane 12 defines an internal space of the tank intended to receive the liquefied gas. The liquefied gas intended to be stored in the tank may in particular be a liquefied natural gas (LNG), that is to say a gas mixture comprising mainly methane as well as one or more other hydrocarbons. The liquefied gas may also be ethane or a liquefied petroleum gas (LPG), that is to say a mixture of hydrocarbons resulting from the refining of petroleum comprising essentially propane and butane.

[0086] The secondary thermally insulating barrier 20 comprises secondary corner insulating panels 21 according to a first embodiment, arranged along the edge, adjacent to the edge and resting against the supporting structure 101. The first embodiment of a secondary corner insulating panel 21 is illustrated in more detail in [Fig.3].

[0087] The secondary thermally insulating barrier 20 also comprises insulating elements 22 which are positioned so as to fill a space located between the secondary corner insulating panels 21 of the first wall and the secondary corner insulating panels 21 of the second wall. The insulating elements 22 are for example made of compressible material chosen from glass wool, rock wool and polyester wadding, polystyrene, which may be expanded polystyrene (EPS), polyurethane foam (PU) which may be reinforced and which may comprise fibers.

[0088] The primary thermally insulating barrier 30 comprises primary thermally insulating corner panels 31.

[0089] The primary waterproof membrane 12 is for example a corrugated membrane (not shown) made of stainless steel having two series of undulations in two directions perpendicular to each other. Other details of such a membrane are described in particular in document WO2010040922A1.

[0090] The secondary waterproof membrane 11 is for example made of Invar®: that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.106 and 2.106 K1 or in an alloy of iron and manganese whose coefficient of expansion is typically between 7.106 and 9.106 K1. The secondary waterproof membrane 11 mainly comprises metal strakes (shown in dotted lines in [Fig.2]). Central metal strakes 60 comprise a flat portion 62 resting on an upper surface of the secondary insulating barrier and two raised edges 63, 64 projecting towards the inside of the tank relative to the flat portion 62. The central metal strakes 60 are juxtaposed and welded together in a sealed manner at the raised edges 63, 64.

[0091] The first embodiment of a secondary corner insulating panel 21 is described in more detail below, with Figures 2 and 3.

[0092] The secondary corner insulating panel 21 has the general shape of a rectangular parallelepiped having a length of approximately 1000 mm. The secondary corner insulating panel 21 comprises an insulating foam block 23 sandwiched between a bottom plate 24 and a first cover plate 25a, a second cover plate 25b and a third cover plate 25c located next to each other and facing the bottom plate 24. The insulating foam block 23 is, for example, made of polyurethane reinforced with fibers. The foam block is for example glued to the first bottom plate 24 and glued to the first, second and third cover plates 25a, 25b, 25c. The foam block may comprise three pieces of foam glued to the first bottom plate 24 and to the three cover plates 25a, 25b, 25c.

[0093] The glue is for example chosen from: cyanoacrylates, neoprenes, epoxies and polyurethanes.

[0094] The base plate 24 and the cover plates 25a, 25b, 25c are rigid and made for example from plywood or from a composite comprising resin and fibers.

[0095] The second cover plate 25b is spaced from the first cover plate 25a by a first relaxation slot 50 and the second cover plate 25b is spaced from the third cover plate 25c by a second relaxation slot 51.

[0096] In other words, the first cover plate 25a is spaced from the second cover plate 25b by the first relaxation slot 50 and the third cover plate 25c is spaced from the second cover plate 25b by the second relaxation slot 51.

[0097] The first and second relaxation slots 50, 51 extend in a thickness direction E of the insulating foam block 23 over a depth of approximately 51% of the thickness of the insulating foam block 23. This depth can be adapted and be for example between 55% and 80%, for example 60% or 70% of the thickness of the insulating foam block 23.

[0098] The first and second relaxation slots 50, 51 further extend in a direction orthogonal Y to the edge, over the entire foam block.

[0099] The first and second relaxation slots 50, 51 have, for example, a width L of between 0.1 mm and 5 mm, for example 4 mm. In this case, the relaxation slots are for example made by cutting into the secondary corner insulating panel 21 using for example a saw. According to a variant, in the case where the width L is between 0.1 mm and 1 mm and the relaxation slots extend over the entire foam block, said foam block is made by gluing pieces of foam against the bottom plate 24, in an adjacent manner. In this case, the pieces of foam may already have their cover plates before they are glued to the bottom plate 24.

[0100] The secondary corner insulating panel 21 further comprises a metal anchoring plate 40 which is housed in a recess of each of the first, second and third cover plates 25a, 25b, 25c, at the center of the first, second and third cover plates 25a, 25b, 25c. The secondary corner insulating panel 21 comprises a first anchoring well 170 and a second anchoring well 171.

[0101] The first anchoring well 170 passes through the secondary corner insulating panel 21 at the level of the first cover plate 25a, between the anchoring plate 40 and the end of the first cover plate 25a which is opposite the first relaxation slot 50.

[0102] The second anchoring well 171 passes through the secondary corner insulating panel 21 at the third cover plate 25c, between the anchoring plate 40 and the end of the first cover plate 25a which is opposite the second relaxation slot 51.

[0103] Preferably, the second cover plate 25b does not include an anchoring well as shown in [Fig.3].

[0104] Each corner secondary insulating panel 21 is fixed to one of the load-bearing walls 104, 107 via a first fixing device (not shown) which is housed in the first anchoring well 170 and a second fixing device 80 which is housed in the second anchoring well 171 to fix the secondary insulating panel 21 to the load-bearing wall 104, 107.

[0105] The fixing device 80 comprises in particular a threaded stud 43 which is welded to one of the load-bearing walls 104, 107 and a support plate 81 crossed by the threaded stud 43 and positioned against an internal surface of the bottom plate 24 by means of a bolt 82 screwed onto the threaded stud 43 in order to fix the secondary corner insulating panel 21 to the load-bearing wall 104, 107. Optionally, Belleville washers, not shown, can also be mounted on the threaded stud 43 and interposed between the support plate 81 and the bolt 82. Such wells and fixing devices are, for example, illustrated in [Fig.l] of document FR2724623.

[0106] The cover plates 25 of the secondary corner insulating panels 21 each have a recess 125 in which is housed an anchoring plate 40 which is preferably metallic.

[0107] The recess 125 is, for example, located at the center of a cover plate 25. It has an internal section having a first dimension and an external section having a second dimension greater than the first dimension so as to provide a shoulder. The anchoring plate 40 has a shape complementary to that of the recess 125.

[0108] Thus, the internal face of the anchoring plate 40 is flush with the internal face of the cover plate 25 of the secondary corner insulating panel 21 so as to form a flat surface on which a corner metal strip 13 of the secondary waterproof membrane 11 is welded. In addition, the anchoring plate 40 has an external section having a larger dimension than its internal section so that the external section of said anchoring plate 40 is in abutment against the shoulder of the recess. The anchor plate 40 can further be glued to the secondary corner insulation panel 21.

[0109] The metal anchor plates 40 each have a first threaded bore 41 and a second threaded bore 42 which are spaced apart from each other in a transverse direction Y, orthogonal to the direction of the edge. In the embodiment shown, the metal anchor plates 40 have an oblong shape with a larger dimension which is oriented in a transverse direction Y orthogonal to the direction of the edge. A circular shape could also be suitable for the metal anchor plates 40.

[0110] The metal corner strips 13 of the first and second tank walls meet at a first edge and form a metal corner with an angle corresponding to the angle formed between the first and second load-bearing walls 104, 107, namely approximately 135° in the embodiment shown. The secondary waterproof membrane 11 further comprises corner strakes 65 which each have a first raised edge 66 which is welded to a raised edge 64 of a central strake 60 and a second flat edge 67 which is opposite the first raised edge 66 and which is welded to a metal corner strip 13.

[0111] The primary thermally insulating corner panels 31 comprise an insulating foam 32 sandwiched between a bottom plate 33 and a cover plate 34.

[0112] Furthermore, the bottom plate 33 comprises two orifices 35 spaced from each other by a distance corresponding to the spacing between the first and second tapped bores 41, 42.

[0113] Each primary thermally insulating corner panel 31 is positioned on the corner metal strip 13 of the secondary waterproof membrane 11, straddling two adjacent cover plates 25 belonging to the same secondary insulating corner panel 21 or to two adjacent secondary insulating corner panels 21.

[0114] Each primary corner thermally insulating panel 31 is fixed to the adjacent secondary corner insulating panel 21 or secondary corner insulating panels 21 via two primary fixing devices 83 each comprising two threaded studs 84 which are each fixed to a tapped bore 41, 42 of the anchor plate 40. The two threaded studs pass through the corner metal strip 13 of the secondary waterproof membrane 11 and the bottom plate 33. The corner metal strip 13 is welded to said metal plates 40 all around the threaded studs 84.

[0115] Optionally, Belleville washers, not shown, may also be mounted on the threaded stud 83 and interposed between the support plate 85 and the bolt 86.

[0116] Optionally, the primary fastening devices are as illustrated in [Fig. 6]. A primary fastening device 183 has a dual functionality, that is to say that it ensures both the anchoring of the primary corner insulating panels 31 and also the anchoring of the corner strake 65. The primary fastening device 183 comprises a stud 184 as the primary fastening device 83 comprises a pin 91 which is intended to pass through an orifice provided in the corner strake 65. The pin 91 comprises a threaded end, not illustrated, which is intended to be screwed into a tapped bore of an anchoring plate. Furthermore, the pin 91 comprises a collar 92 extending radially relative to the axis of the pin 91. The collar 92 is intended to press the corner strake 65 when the pin 92 is screwed into the tapped bore of the anchor plate.Furthermore, the collar 92 is welded in a watertight manner to the corner strake 65 all around the orifice, which ensures the watertightness of the passage of the pin 91 through the secondary sealing membrane 11.

[0117] Each primary fixing device 83 further comprises a primary support plate 85 which is crossed by the threaded studs 84 and positioned against an internal surface of the bottom plate 33 by means of a bolt 86 screwed onto the threaded stud 84 in order to fix the first primary thermally insulating corner panel 31 against the metal corner strip 13 of the secondary waterproof membrane 11.

[0118] The cover plates 34 comprise metal inserts (not shown) onto which a metal angle iron of a primary metal waterproof membrane 12 is welded.

[0119] In relation to [Fig.4], a secondary corner panel according to a second embodiment is described below.

[0120] In [Fig.4], the reference numerals relating to elements identical or similar to those of [Fig.3] have the same reference incremented by 100.

[0121] The secondary corner insulating panel 121 differs from the secondary corner insulating panel 21 in that the first slot 150 and the second slot 151 extend along the entire thickness E of the insulating foam block 123 to the bottom plate 124, without passing through the bottom plate 124. In other words, the first and second relaxation slots 150, 151 separate the foam block 123 into three separate pieces of foam, spaced from each other by the first and second relaxation slots 150, 151.

[0122] Such a secondary corner panel 121 has a total length of approximately 1000 mm, i.e. three pieces of foam of approximately 320 mm in length each with the first and second relaxation slots 150, 151 which each have a width L of approximately 20 mm.

[0123] Flat gaskets made of thermally insulating compressible material (not shown) may be housed in the first and second relaxation slots 150, 151.

[0124] Furthermore, the secondary corner insulating panel 121 comprises three pairs of anchoring wells 172, 173, 174, 175, 270, 271. Each of the pairs passes through the thickness E of the insulating panel at a cover plate.

[0125] The first pair of wells comprises a first and a second well 175, 270 which are arranged on either side of the anchoring plate 40 of the first cover plate 125 a.

[0126] The second pair of wells comprises a first and a second well 173, 174 which are arranged on either side of the anchoring plate 40 of the second cover plate 125b.

[0127] The third pair of wells comprises a first and a second well 172, 271 which are arranged on either side of the anchoring plate 140 of the third cover plate 125c.

[0128] With reference to [Fig. 5], a cutaway view of an LNG carrier ship 70 shows a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealed membrane intended to be in contact with the LNG contained in the tank, a secondary sealed membrane arranged between the primary sealed membrane and the double hull 72 of the ship, and two thermally insulating barriers arranged respectively between the primary sealed membrane and the secondary sealed membrane and between the secondary sealed membrane and the double hull 72.

[0129] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer a cargo of LNG from or to the tank 71.

[0130] [Fig. 5] represents an example of a maritime terminal comprising 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 installation comprising a mobile arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The orientable mobile arm 74 adapts to all sizes of LNG carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75.The underwater pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore installation 77 on a . great distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

[0131] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the shore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0132] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0133] The use of the verb “comport” or “comprendre” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0134] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. A sealed and thermally insulating tank for storing and / or transporting liquefied gas, the tank comprising a first tank wall fixed to a first load-bearing wall (104) of a load-bearing structure (101) and a second tank wall fixed to a second load-bearing wall (107) of the load-bearing structure, the second load-bearing wall joining the first load-bearing wall at an edge of the load-bearing structure, wherein the first tank wall comprises a multi-layer structure comprising, from the outside to the inside of the tank, a secondary thermally insulating barrier (20) anchored against the load-bearing structure, a secondary sealed membrane (11) which is carried by the secondary thermally insulating barrier, a primary thermally insulating barrier (30) and a primary sealed membrane (12) which is carried by the primary thermally insulating barrier and which is intended to be in contact with the liquefied gas contained in the tank,wherein the secondary thermally insulating barrier comprises a secondary corner insulating panel (21, 121) which runs along the edge and is adjacent to the edge, the secondary corner insulating panel comprises an insulating foam block (23, 123) sandwiched between a base plate (24, 124) and cover plates (25a, 25b, 25c, 125a, 125b, 125c) each located opposite the base plate, the cover plates being spaced apart from each other by relaxation slots (50, 51, 150, 151) which develop in a thickness direction (E) of the insulating foam block and in a direction transverse (Y) to the edge, wherein the relaxation slots have a depth of at least half the thickness of the insulating foam block.,

2. A tank according to claim 1, wherein the secondary corner insulation panel comprises at least three cover plates (25a, 25b, 25c, 125a, 125b, 125c).

3. Tank according to claim 1 or 2, in which the relaxation slots extend over at least 60% of the thickness of the insulating foam block, preferably over at least 80% of the thickness of the insulating foam block.

4. Tank according to one of claims 1 to 3, in which the relaxation slots (150, 151) extend over the entire thickness of the insulating foam block, up to the bottom plate (124).

5. Tank according to one of claims 1 to 4, in which the depth of the relaxation slots is identical.

6. Tank according to one of claims 1 to 5, in which the insulating foam block has n internal faces spaced from each other by the relaxation slots, and in which the secondary corner insulating panel comprises n cover plates each covering one of said internal faces; with n: an integer.

7. Tank according to one of claims 1 to 6, wherein the secondary corner insulating panel comprises a first anchoring well (170, 175, 270) and a second anchoring well (171, 172, 271) which pass through a thickness of the secondary corner insulating panel, the first anchoring well passes through the cover plate which is located at a first end of the secondary corner insulating panel, and the second anchoring well passes through the cover plate which is located at a second end of the secondary corner insulating panel, and comprising first and second wall anchoring devices (80) each comprising an external portion (43) fixed to the supporting structure and an internal portion respectively located in the first and second anchoring wells and fixing the secondary corner insulating panel to the supporting structure.

8. Tank according to one of claims 1 to 7, in which the secondary corner insulating panel comprises metal plates (40, 140) each fixed to one of the cover plates, in which the metal plates each comprise a first threaded bore (41, 141), in which threaded studs (84) anchor primary thermally insulating corner panels of the primary thermally insulating barrier to the secondary corner insulating panel, the threaded studs comprising a through portion which comprises a collar and which passes in a sealed manner through the secondary waterproof membrane; a first end which is fixed in the first threaded bore retaining the collar against the secondary waterproof membrane at the metal plate and a second end which is equipped with a support member (85, 86) retaining the primary thermally insulating corner panel to the secondary insulating corner panel, in which the secondary waterproof membrane is welded to said metal plates around the threaded studs.

9. A tank according to claim 8, wherein the secondary waterproof membrane comprises metal strakes (60) comprising a flat portion resting on an upper surface of the secondary insulating barrier and two raised edges projecting towards the inside of the tank relative to the central portion, the strakes being juxtaposed and welded together in a sealed manner at the raised edges (63, 64), wherein the secondary waterproof membrane comprises a corner metal strip (13) comprising a portion welded to an adjacent metal strake and a portion welded to each of the metal plates of the corner secondary insulating panel.

10. A tank according to claim 8, wherein the secondary waterproof membrane comprises metal strakes (60) comprising a flat portion resting on an upper surface of the secondary insulating barrier, at least one corrugation and two edges, the strakes being juxtaposed with each other and welded together in a sealed manner at the edges, wherein the secondary waterproof membrane comprises a metal corner strip (13) comprising a portion welded to an adjacent metal strake and a portion welded to each of the metal plates of the secondary corner insulating panel.

11. A ship (70) for transporting a liquefied gas, the ship comprising a double hull (72) and a tank (71) according to one of claims 1 to 10, the double hull comprising the supporting structure.

12. A transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 11, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the vessel to a floating or land-based storage facility (77) and a pump for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank.

13. A method of loading or unloading a ship (70) according to claim 11, wherein a liquefied gas is supplied to through insulated pipelines (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the ship (70).

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