Liquefied gas storage facility with a tensioned secondary membrane

Abstract

The invention relates to a liquefied gas storage facility in which the secondary thermally insulating barrier (7) of the ceiling wall (4) comprises a first row (60) of first insulating panels (62) arranged between the rear transverse edge (49) of the loading / unloading opening (14) and the rear cofferdam wall (82); the secondary waterproofing membrane (9) of the ceiling wall (4) comprising, between the rear transverse edge (49) and the rear cofferdam wall (82), a plurality of parallel first strakes (64) extending in the longitudinal direction, interrupted by the rear transverse edge (49), each first strake (64) comprising a flat central portion (65) and two raised edges (66), and in which the first insulating panels (62) are equipped with strake anchoring devices (69, 81), the flat portion (65) of each of the first strakes (64) being welded to one of the strake anchoring devices (69, 81).Figure for abstract: 8.

Description

Title of the invention: Installation for storing liquefied gas with a tensioned secondary membrane Technical field

[0001] The invention relates to the field of liquefied gas storage installations comprising a sealed and thermally insulating tank with a sealed membrane.

[0002] 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 Petroleum Gas (also called LPG) having for example a temperature between -50°C and 0°C, or 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.

[0003] The storage facility may be installed on land or on a floating structure. In the case of a floating structure, the facility may 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

[0004] Document KR20200144697 describes a liquefied gas storage facility comprising a tank integrated into the supporting structure of a ship. The walls of the tank have a multi-layer structure comprising, in the thickness direction from the outside to the inside, a secondary thermally insulating barrier retained to the supporting structure, a secondary sealing membrane attached to the secondary thermally insulating barrier, a primary thermally insulating barrier attached to the secondary thermally insulating barrier through the secondary sealing membrane and a primary sealing membrane which is attached to the primary thermally insulating barrier and which is intended to be in contact with the liquefied gas stored inside the tank. The secondary sealing membrane has a plurality of parallel strakes.Each strake comprises a flat central portion which extends in the longitudinal direction of the tank and two raised edges arranged on either side of the flat central portion and projecting towards the inside of the tank relative to the central portion. Such a secondary waterproofing membrane, commonly referred to as a "tensioned membrane", does not allow the absorption of tensile and compressive forces in the longitudinal direction unlike a corrugated membrane.

[0005] The ceiling wall of the tank is interrupted at a loading / unloading opening which is crossed by pipes intended for loading and / or unloading the liquefied gas. The secondary sealing membrane is stopped and is directly connected to the supporting structure by means of secondary connecting angles in order to take up the tensile and compressive forces resulting in particular from the thermal contraction of the secondary sealing membrane and the deformation of the ship's hull linked to the bending of the ship's beam.In order to relieve the secondary connecting angles, the secondary thermally insulating barrier has, along the front transverse edge of the loading / unloading opening, a particular arrangement comprising in particular a plurality of secondary, metallic fixing supports to which secondary stop beams are fixed against which one of the secondary connecting angles rests.

[0006] The rear transverse edge of the loading / unloading opening is positioned relatively close to the rear cofferdam wall of the tank. Thus, the secondary connecting angle iron which is positioned along the rear transverse edge is subjected to less significant forces than that which is arranged along the front transverse edge. Also, the secondary thermally insulating barrier does not comprise along the rear transverse edge a particular arrangement of the aforementioned type with secondary stop beams and secondary fixing supports. Furthermore, in the area to the rear of the loading / unloading opening, only the ends of the strakes are fixed on the one hand to a mechanically welded structure, along the rear cofferdam wall, and, on the other hand, to the connecting angle iron along the rear transverse edge of the loading / unloading opening.

[0007] Such an arrangement is not entirely satisfactory, in particular in that the failure to fix the strakes between the mechanically welded structure and the secondary connecting angle iron is likely to cause the strakes to tear off, in particular when they are subjected to excess pressure in the secondary insulating thermal barrier. Summary of the invention

[0008] One idea underlying the invention is to provide a liquefied gas storage facility of the aforementioned type that is more resistant in the area between the loading / unloading opening and the rear cofferdam wall.

[0009] According to a first aspect, the invention provides a liquefied gas storage facility comprising a supporting structure and a sealed and thermally insulating tank supported by the supporting structure, the supporting structure comprising an upper supporting wall and the tank comprising a ceiling wall which is fixed to the upper supporting wall, said ceiling wall comprising, in one direction thick, from the outside to the inside of the tank, a secondary thermally insulating barrier fixed to the upper load-bearing wall, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane, and a primary sealing membrane resting against the primary thermally insulating barrier and intended to be in contact with the liquefied gas, said ceiling wall being interrupted locally so as to delimit a loading / unloading opening intended to be crossed by loading / unloading pipes, said loading / unloading opening being defined by a front transverse edge and a rear transverse edge parallel to a transverse direction and a first and a second longitudinal edge parallel to a longitudinal direction perpendicular to the transverse direction; the secondary thermally insulating barrier of the ceiling wall comprising a first row of first insulating panels, said first insulating panels being aligned in the transverse direction, and arranged between the rear transverse edge and the rear cofferdam wall; the secondary waterproofing membrane of the ceiling wall comprising, between the rear transverse edge and the rear cofferdam wall, a plurality of first parallel strakes extending in the longitudinal direction, interrupted by the rear transverse edge, each first strake comprising a flat central portion resting against the first insulating panels and two raised edges projecting towards the inside of the tank relative to the central portion, the first strakes being juxtaposed in the transverse direction in a repeated pattern and welded together in a watertight manner at the raised edges, and wherein the first insulating panels are equipped with strake anchoring devices, the flat portion of each of the first strakes being welded to one of the strake anchoring devices.

[0010] Thus, thanks to the strake anchoring devices, the strakes of the secondary membrane are correctly anchored in the area located between the rear cofferdam wall and the loading / unloading opening, which prevents them from being torn off in the event of overpressure in the secondary thermally insulating barrier.

[0011] According to embodiments, such an installation may comprise one or more of the following characteristics.

[0012] According to one embodiment, each first insulating panel is equipped with a single strake anchoring device. This makes it possible to limit the stresses in the secondary waterproofing membrane, when the first insulating panels contract when the tank is cooled.

[0013] According to one embodiment, each strake anchoring device is arranged at middle of the respective first insulating panel in the transverse direction.

[0014] According to one embodiment, the strake anchoring device is arranged in the middle of the respective first insulating panel in the longitudinal direction.

[0015] According to one embodiment, the strake anchoring device is arranged in the middle of the strakes in the transverse direction.

[0016] According to one embodiment, the first insulating panels have a transverse dimension equal to a transverse dimension of the first strakes and are each aligned with one of the first strakes so that the raised edges of the first strakes are located directly above a gap between two adjacent first insulating panels.

[0017] According to one embodiment, the first insulating panels are devoid of welding supports for fixing the raised edges of the strakes to the first insulating panels. In other words, the raised edges of the first strakes are directly welded to each other in the area of ​​the first insulating panels.

[0018] According to one embodiment, each strake anchoring device comprises: - a plate fixed to one of the first secondary insulating panels, - a pin fixed to said plate and extending in a direction of thickness of the ceiling wall from said plate towards the inside of the tank and passing in a sealed manner through an orifice provided in the flat portion of one of the first strakes; said pin comprising a collar fixed in a sealed manner to the first strake around said orifice. Such a strake anchoring device is advantageous in that it is simple to install and use.

[0019] According to one embodiment, the secondary thermally insulating barrier of the ceiling wall comprises a second row of second insulating panels, said second insulating panels being aligned in the transverse direction, and arranged between the first row of first insulating panels and the rear cofferdam wall.

[0020] According to one embodiment, the second insulating panels are equipped with strake anchoring devices, the flat portion of at least part of the first strakes being welded to one of the strake anchoring devices of the second insulating panels.

[0021] According to one embodiment, said second insulating panels are devoid of a groove each receiving a welding support on which one of the raised edges of two first adjacent strakes is welded.

[0022] According to one embodiment, the first strakes are welded along the rear transverse edge to a secondary connecting angle which is connected to the upper load-bearing wall.

[0023] According to one embodiment, the secondary thermally insulating barrier of the ceiling wall includes: - at least one first and one second secondary fixing bracket positioned along the rear transverse edge; the first and second secondary fixing brackets each comprising a secondary foot which is anchored to the upper load-bearing wall, a secondary cap which is welded to the secondary foot and which extends parallel to the longitudinal direction, in a plane parallel to the upper load-bearing wall and a plate which is fixed to the secondary cap by fixing members; - at least one secondary edge insulating block which is arranged along the first transverse edge, between the first and the second secondary fixing brackets;and - at least one secondary stop beam which extends along the rear transverse edge and rests at least against the secondary cap of each of the first and second secondary fixing brackets and against one of the secondary edge insulating blocks, said secondary stop beam being blocked, in the thickness direction of the ceiling wall, between the plate and the secondary cap of each of the first and second secondary fixing brackets; ; the secondary connecting angle comprising a first flange which rests against the secondary stop beam and a second flange which is connected to the upper load-bearing wall.

[0024] Thus, such an arrangement of the secondary thermally insulating barrier, along the rear edge, makes it possible to relieve the corresponding secondary connecting angle. This makes it possible to move the loading / unloading opening further away from the rear cofferdam wall without risking the secondary connecting angle which is arranged along the rear transverse edge being subjected to excessive forces.

[0025] According to one embodiment, the first and second secondary fixing supports carry a primary anchoring device intended to ensure anchoring of the primary thermally insulating barrier and some of the strake anchoring devices which equip the first insulating panels are aligned in the longitudinal direction L with the primary anchoring device.

[0026] According to one embodiment, the primary thermally insulating barrier of the ceiling wall comprises, in an area positioned between the rear cofferdam wall and the rear transverse edge, primary insulating panels which are arranged astride the secondary stop beam and insulating elements of a corner structure which is arranged at the junction between the ceiling wall and the rear cofferdam wall. This makes it possible to avoid or at least limit walking phenomena in the support surface of the primary waterproofing membrane.

[0027] According to one embodiment, the primary insulating panels of the area positioned between the rear cofferdam wall and the rear transverse edge comprise recesses, receiving the strake anchoring devices.

[0028] According to one embodiment, the first strakes are welded to a mechanically welded structure running along an edge between the ceiling wall and the rear cofferdam wall and fixed to the ceiling wall and to the rear cofferdam wall.

[0029] An installation according to one of the aforementioned embodiments may be a land-based storage installation, for example for storing LNG or may be installed in a floating, coastal or deep-water structure, in particular an ethane or methane carrier, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO) and others. In the case of a floating structure, the tank may be intended to receive liquefied natural gas serving as fuel for the propulsion of the floating structure.

[0030] According to one embodiment, the invention relates to a ship for transporting a fluid which comprises an installation of the aforementioned type.

[0031] According to one embodiment, the ship comprises a double hull which forms the supporting structure.

[0032] According to one embodiment, the invention also provides a transfer system for a fluid, the system comprising the aforementioned vessel, insulated pipes arranged to connect the vessel's tank to a floating or land-based storage facility and a pump for driving a flow of fluid through the insulated pipes from or to the floating or land-based storage facility to or from the vessel's tank.

[0033] According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a fluid is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the ship's tank.

[0034] According to a second aspect capable of being implemented independently of the first aspect, the invention relates to a liquefied gas storage facility comprising a supporting structure and a sealed and thermally insulating tank supported by the supporting structure, the supporting structure comprising an upper supporting wall and the tank comprising a ceiling wall which is fixed to the upper supporting wall, said ceiling wall comprising, in a thickness direction, from the outside to the inside of the tank, a secondary thermally insulating barrier fixed to the upper supporting wall, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane, and a primary sealing membrane resting against the primary thermally insulating barrier and intended to be in contact with the liquefied gas,said ceiling wall being interrupted locally so as to delimit a loading / unloading opening intended to be crossed by loading / unloading pipes, said loading / unloading opening being defined by a front transverse edge and a rear transverse edge parallel to a transverse direction and a first and a second longitudinal edge parallel to a longitudinal direction perpendicular to the transverse direction; the secondary thermally insulating barrier of the ceiling wall comprises: - at least one first and one second secondary fixing bracket positioned along the rear transverse edge; the first and second secondary fixing brackets each comprising a secondary foot which is anchored to the upper load-bearing wall, a secondary cap which is welded to the secondary foot and which extends parallel to the longitudinal direction, in a plane parallel to the upper load-bearing wall and a plate which is fixed to the secondary cap by fixing members; - at least one secondary edge insulating block which is arranged along the first transverse edge, between the first and the second secondary fixing brackets;and - at least one secondary stop beam which extends along the rear transverse edge and rests at least against the secondary cap of each of the first and second secondary fixing brackets and against one of the secondary edge insulating blocks, said secondary stop beam being blocked, in the thickness direction of the ceiling wall, between the plate and the secondary cap of each of the first and second secondary fixing brackets.;

[0035] Thus, such an arrangement of the secondary thermally insulating barrier, along the rear edge, makes it possible to relieve the corresponding secondary connecting angle. This makes it possible to move the loading / unloading opening further away from the rear cofferdam wall without risking the secondary connecting angle, arranged along the rear transverse edge, being subjected to excessive forces. Brief description of the figures

[0036] 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.

[0037] [Fig.l] is a schematic view of a ship having a storage facility.

[0038] [Fig.2] is a partial perspective view from below of a ceiling wall according to a first embodiment, in an area close to a loading / unloading opening interrupting the ceiling wall of the tank, said view corresponding to detail II of [Fig.l].

[0039] [Fig. 3] is a longitudinal sectional view of the ceiling wall, close to the rear cofferdam wall.

[0040] [Fig.4] is a partial perspective view of the secondary thermally insulating barrier, along the rear transverse edge of the loading / unloading opening.

[0041] [Fig.5] is a perspective view of a secondary mounting bracket.

[0042] [Fig.6] is a partial cross-sectional view of the thermally insulating barrier secondary, along the rear transverse edge of the loading / unloading opening.

[0043] [Fig.7] is a perspective view of a beam intended to rest against the secondary fixing supports.

[0044] [Fig.8] is a partial perspective view of the ceiling wall between the rear transverse edge of the loading / unloading opening and the rear cofferdam wall illustrating the arrangement of the secondary thermally insulating barrier and the secondary waterproofing membrane in this area.

[0045] [Fig.9] is a partial perspective view of the secondary thermally insulating barrier of the ceiling wall between the rear transverse edge of the loading / unloading opening and the rear cofferdam wall.

[0046] [Fig. 10] illustrates a device for anchoring strakes according to one embodiment.

[0047] [Fig. 11] illustrates a device for anchoring strakes which also provides a function anchoring of primary panels.

[0048] [Fig. 12] is a schematic cutaway representation of a LNG carrier tank and a loading / unloading terminal for this tank. Description of the embodiments

[0049] 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 exterior and interior of the tank. Furthermore, in the figures, the arrows L and T correspond respectively to the longitudinal and transverse directions of the tank, perpendicular to each other. By extension, in the embodiments shown, the arrows L and T also correspond to the longitudinal and transverse directions of the ship since, in these embodiments, the tanks have the same orientation as the ship.

[0050] [Fig. 1] shows a ship 70, for example a LNG carrier, for the storage and transport of liquefied gas. The ship 70 comprises a storage facility 1 comprising several tanks 71 arranged in the inner hull of the ship. To this end, the inner hull has a plurality of polyhedral-shaped compartments which are defined by a plurality of load-bearing walls and which are each intended to form a load-bearing structure receiving one of the tanks 71 of the ship 1. The inner hull comprises cofferdam load-bearing walls which extend transversely to the longitudinal direction tudinal L of the ship and which delimit cofferdam spaces segmenting the internal hull into several compartments.

[0051] Each tank 71 is polyhedral in shape and comprises a plurality of tank walls assembled together and fixed against the load-bearing walls, and in particular a ceiling wall 4, a rear cofferdam wall 82 and a front cofferdam wall 83. The front 83 and rear 82 cofferdam walls are spaced apart in the longitudinal direction L of the ship 70 and are fixed against one and the other of the two load-bearing cofferdam walls.

[0052] In order to load the liquefied gas into the tank and unload it, a loading / unloading opening, not shown in [Fig.l], is provided in the ceiling wall 4 and through which pipes for loading and / or unloading the liquefied gas pass. The loading / unloading opening is provided in the ceiling wall 4 near the rear cofferdam wall 82 (zone II of [Fig.l]).

[0053] The upper load-bearing wall of the load-bearing structure 2 is also provided with orifices allowing the pipes to pass through the load-bearing structure 2. The loading / unloading opening serves as a penetration point for various liquefied natural gas handling equipment, and in particular one or more of the following equipment: a filling line, an emergency pumping line, unloading lines linked to unloading pumps, a spray line, a feed line linked to a spray pump, etc. According to one embodiment, a loading / unloading tower, not shown, passes through the loading / unloading opening. The loading tower has vertical masts which are fixed to each other by crosspieces. The vertical masts are hollow and thus each define a loading line, a loading line or an emergency shaft allowing the descent of an emergency shaft.

[0054] [Fig. 2] shows a perspective view of a ceiling wall 4 from inside the tank in an area close to the loading / unloading opening 14. The loading / unloading opening 14 has a rectangular shape and is defined by two longitudinal edges 5, parallel to the longitudinal direction L of the tank and two transverse edges, namely a front transverse edge 6 and a rear transverse edge 49, parallel to the transverse direction.

[0055] In relation to [Fig. 3], the multi-layer structure of the ceiling wall 4 is observed. The ceiling wall 4 comprises successively, in the thickness direction, from the outside to the inside of the tank, a secondary thermally insulating barrier 7 retained on the upper load-bearing wall 8, a secondary sealing membrane 9 bearing against the secondary thermally insulating barrier 7, a primary thermally insulating barrier 10 bearing against the secondary sealing membrane 9 and a primary sealing membrane 11 bearing against the primary thermally insulating barrier 10 and intended to be in contact with the liquefied natural gas contained in the tank.

[0056] The secondary thermally insulating barrier 7 comprises a plurality of secondary insulating panels 12 which are anchored to the upper load-bearing wall 8 by means of secondary anchoring devices, not shown in [Fig. 3], or by bonding with mastic. The secondary insulating panels 12 have a generally parallelepiped shape and are, for example, arranged in parallel rows, in the longitudinal direction L and in the transverse direction T.

[0057] The secondary sealing membrane 9 of the ceiling wall 4 comprises a continuous layer of metal strakes, with raised edges. Each strake extends in the longitudinal direction L and comprises a flat central portion resting on the secondary insulating panels 12. Each strake also comprises two raised edges arranged on either side of the flat central portion and projecting towards the inside of the tank relative to the central portion. The strakes are welded by their raised edges to parallel welding supports which are fixed in grooves formed in the internal surface of the secondary insulating panels, that is to say the one which is in contact with the secondary sealing membrane 9, with the exception of the strakes of the ceiling wall 4 which are positioned at the rear of the loading / unloading opening 14 which have a different anchoring method.The strakes are, for example, 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 an alloy of iron and manganese whose coefficient of expansion is typically between 7.106 and 9.106 K1. .

[0058] The primary thermally insulating barrier 10 comprises a plurality of primary insulating panels 13 which are anchored to the secondary insulating panels 12 by means of primary anchoring devices, also not shown in [Fig. 3]. The primary insulating panels 13 have a generally parallelepiped shape. The primary insulating panels 13 may in particular be positioned offset from the secondary insulating panels 12 in the longitudinal direction L, and optionally also in the transverse direction T.

[0059] According to one embodiment, the secondary insulating panels 12 and the primary insulating panels 13 comprise a base plate, a cover plate and one or more layers of insulating polymer foam which are sandwiched between the base plate and the cover plate and are bonded to them. The insulating polymer foam may in particular be a polyurethane-based foam, optionally reinforced with fibers, in particular glass fibers.

[0060] The primary sealing membrane 11 comprises a plurality of metal plates corrugated juxtaposed in the longitudinal direction L and the transverse direction T, and welded to each other along their edges. The primary waterproofing membrane 11 comprises corrugations extending parallel to the longitudinal direction L and corrugations extending parallel to the transverse direction T.

[0061] In order to delimit the loading / unloading opening 14, the ceiling wall 4 is interrupted locally. Thus, the sealing membranes, primary 11 and secondary 9, as well as the thermally insulating barriers, primary 10 and secondary 7, are interrupted all around the loading / unloading opening 14.

[0062] Returning to [Fig. 2], a cover 15 is seen arranged in the loading / unloading opening 14. The cover 15 comprises a metal sealing wall 16 and a thermal insulation structure 17 located between the metal sealing wall 16 and the upper load-bearing wall 8. The cover 15 is fixed to the upper load-bearing wall 8. The metal sealing wall 16 provides continuity of the seal with the primary sealing membrane 11 of the ceiling wall 4 while the thermal insulation structure 17 provides continuity of the insulation.

[0063] The thermal insulation structure 17 may comprise one or more cover insulating blocks, made for example in the form of boxes comprising a base plate, a cover plate and load-bearing spacers extending, in the thickness direction, between the base plate and the cover plate and delimiting a plurality of compartments filled with an insulating filling, such as perlite, glass wool or rock wool. The cover insulating block(s) comprise holes (not shown) allowing the loading / unloading pipes to pass through.

[0064] The metal sealing wall 16 of the cover 14 comprises, for example, a plurality of metal plates welded to each other. The metal sealing wall 16 further comprises a plurality of cover orifices (not shown) intended to be traversed by the loading / unloading pipes. A metal connecting strip 18 makes it possible to connect in a sealed manner the metal sealing wall 16 of the cover 14 and the primary sealing membrane 11 of the ceiling wall 4, as visible in [Fig. 2].

[0065] If at the loading / unloading opening 14, the primary sealing membrane 11 is connected to the metal sealing wall 16 of the cover 14, the secondary sealing membrane 9 is interrupted at the longitudinal 5 and transverse 6, 49 edges of the loading / unloading opening 14 and is directly connected in a sealed manner to the upper load-bearing wall 8. This connection is made using secondary connecting angles 19, notably visible in [Fig. 3]. The secondary connecting angles 19 comprise a first wing 20 and a second wing 21 connected to the first wing 20. The first wing 20 extends in a horizontal plane and is connected to the secondary waterproofing membrane 9 while the second wing 21 extends in a vertical plane and is welded to an anchoring plate 22 of the upper load-bearing wall 8. Thus, some of the strakes of the secondary waterproofing membrane 9 are interrupted by the loading / unloading opening 14 and are connected to the upper load-bearing wall 8.

[0066] At this connection to the upper load-bearing wall 8, the secondary sealing membrane 9 is capable of transmitting to the secondary connection angles 19 tensile forces linked to the work of the secondary sealing membrane 9, in particular when the tank is cooled. Also, in order to relieve the secondary connection angles 19 and its welding with the secondary sealing membrane 9, the secondary thermally insulating barrier 7 has a particular arrangement along the front 6 and rear 49 transverse edges of the loading / unloading opening 14.

[0067] The particular arrangement of the secondary thermally insulating barrier 7, along the transverse edges, here the rear transverse edge 49, is partially shown in [Fig. 4]. The secondary thermally insulating barrier 7 comprises a plurality of secondary fixing supports 23 which are regularly arranged along said rear transverse edge 49 of the loading / unloading opening 14, at a distance from each other in the transverse direction T, and welded to the upper load-bearing wall 8.

[0068] One of said secondary fixing supports 23 is shown in [Fig. 5]. It comprises a secondary cap 24 which extends parallel to the longitudinal direction, in a plane parallel to the ceiling wall 4. The secondary cap 24 is welded to a secondary foot 25 which is anchored to the upper load-bearing wall 8, for example by welding. The secondary foot 25 comprises two branches 26, 27 connected to each other by a central core 28. The two branches 26, 27 are welded to the two ends of the secondary cap 24 and extend, parallel to each other, in planes parallel to the transverse direction and to the thickness direction of the ceiling wall 4. The central core 28 extends in a plane parallel to the longitudinal direction and to the thickness direction of the ceiling wall 4. The central core 28 is welded to the secondary cap 24 and to the two branches 26, 27.In the embodiment shown, the central core 28 has a U shape. The spacing in the longitudinal direction L between the two branches 26, 27 defines a seat length and makes it possible to oppose the tilting and bending of the secondary connecting angle 19 in this direction.

[0069] The secondary fixing support 23 carries a primary anchoring device 29 intended to ensure the anchoring of the primary thermally insulating barrier 10. The primary anchoring device 29 is fixed to a plate 30 which is, itself, fixed to the secondary cap 24 by fixing members 31, such as screws. The longitudinal direction of the plate 30 is parallel to the longitudinal direction of the tank.

[0070] Furthermore, a threaded stud 32 is fixed to said plate 30 and develops in the thickness direction towards the inside of the tank. The threaded stud 32 is intended to pass in a sealed manner through an orifice provided in the secondary sealing membrane 9. The primary anchoring device 29 also comprises a support element 33 which is intended to come into contact with support zones of primary insulating edge blocks 51 of the primary thermally insulating barrier 10, in particular shown in [Fig. 3], which are arranged along the transverse edges 6, 49 of the loading / unloading opening 14. In the embodiment shown, the support zones of the primary insulating edge blocks 51 are, for example, formed by cleats which are fixed to the ends of said primary insulating edge blocks 51.

[0071] Furthermore, the primary anchoring device 25 also comprises a nut 34, notably visible in [Fig. 5], which cooperates with the thread of the threaded stud 32 so as to ensure the fixing of the support element 33 on the threaded stud 32 as well as Belleville washers 35 which are mounted on the threaded stud 32 between the nut 34 and the support element 33. The primary anchoring device 25 further comprises a collar 36 which is positioned around the threaded stud 32 and is intended to be welded in a sealed manner to the secondary sealing membrane 9 all around the orifice crossed by the threaded stud 32.

[0072] Returning to [Fig. 4], it can be seen that the secondary thermally insulating barrier 7 also comprises, along the transverse edges 6, 49, secondary insulating edge blocks 37. Each secondary insulating edge block 37 is interposed between two neighboring secondary fixing supports 23. The secondary insulating edge blocks 37 are advantageously glued to the upper load-bearing wall 8, for example by means of mastic. The secondary insulating edge blocks 37 are, for example, formed by a wooden box inside which is placed an insulating filling, such as perlite, glass wool or rock wool for example.

[0073] The secondary thermally insulating barrier 7 further comprises secondary stop beams 38 against which the first wing 20 of the secondary connecting angle 19 is fixed. The secondary stop beams 38 are, for example, made of wood. The secondary stop beams 38 also participate in retaining the secondary insulating edge blocks 37 against the upper load-bearing wall 8. The secondary stop beams 38 are thus interposed, in the thickness direction, between the secondary insulating edge blocks 37 and the first wing 20 of the secondary connecting angle 19.

[0074] The secondary stop beams 38 are each fixed astride two secondary fixing supports 23. In the embodiment shown, the secondary stop beams 38 also rest, in their middle part, on a secondary fixing support 23. To ensure the fixing of the secondary stop beams 38, the ends of the secondary stop beams 38 are sandwiched between the plate 30 and the secondary cap 24. The fixing members 31 being adjustable, the ends of the secondary stop beams 38 are thus blocked, in the thickness direction of the ceiling wall, between the plate 30 and the secondary cap 24.

[0075] As illustrated in [Fig.7], the secondary stop beams 38 have recesses 39 in which the plates 30 are received so that said plates 30 are substantially flush with the internal surface of the secondary stop beam 38. This ensures the flatness of the support surface against which the first wing 20 of the secondary connecting angle 19 and the secondary sealing membrane 9 are positioned.

[0076] Advantageously, the secondary stop beams 38 also incorporate, in prefabrication, one or more metal reinforcements, making it possible to increase their rigidity. The metal reinforcements are, for example, metal stiffening blades 40 which are oriented parallel to the length of said secondary stop beams 38, that is to say in the transverse direction of the tank. The metal reinforcements 48 can be fixed to the secondary stop beam 38 by any means, and in particular by fixing screws, by gluing or by riveting.

[0077] According to an advantageous embodiment, sausages or strips of mastic, not illustrated, are positioned between, on the one hand, the secondary stop beams 38 and, on the other hand, the secondary edge insulating blocks 37 and / or the secondary caps 24 of the secondary fixing supports 23. This makes it possible to adjust the position of the secondary stop beams 38 according to the thickness direction of the ceiling wall 4.

[0078] As illustrated in [Fig.7], the secondary stop beams 38 also incorporate support angles 41, L-shaped and made of metal, which serve as support for stop devices 42, visible in particular in FIGS. 4 to 6, and described below. The support angles 41 being harder than the secondary stop beam 38, they make it possible to avoid punching of the secondary stop beams 38 in their contact zones with the stop devices 42. The secondary stop beams 38 also have cutouts 43 which make it possible to receive the stop devices 42 when the secondary stop beams 38 are placed against the secondary fixing supports 23. The support angles 41 each have a first tab 44 which is positioned against the external face of the secondary stop beam 38 and a second tab 45 which is positioned against an edge of one of the cutouts 43 mentioned above. The support angles 41 can be fixed to the secondary stop beams 38 by any means and in particular by fixing screws, by gluing or by riveting. Advantageously, the first tab 44 is embedded in a recess provided in the internal surface of the secondary stop beam 38.

[0079] Furthermore, as illustrated in [Fig. 6], each secondary stop beam 38 is locked in translation, in the longitudinal direction L, on the secondary fixing supports 23 with which it cooperates. To do this, each secondary fixing support 23 comprises a stop device 42 which is fixed on the secondary cap 24. The stop device 42 comprises a plate 43 fixed, by welding, perpendicular to the secondary cap 24. In the embodiment shown, in order to reinforce the rigidity of the stop device 42, a reinforcement in the form of a gusset 46 is welded between the plate 43 and the secondary cap 24. The plate 43 comprises two threaded orifices whose axes are oriented parallel to the longitudinal direction L of the tank and which are each crossed by a pressure screw 44.Each pressure screw 44 is intended to come to bear against one of the support angles 41, which has the effect of pressing the corresponding secondary stop beam 38 against one end 45 of a branch 27, which makes it possible to block it in translation in the longitudinal direction L.

[0080] Thus, the secondary stop beams 38 are rigidly supported by the secondary fixing supports 23, both in the longitudinal direction L and in the thickness direction of the ceiling wall 4, which makes it possible to take up the tensile or compressive forces which may be exerted by the secondary waterproofing membrane 9 in operation.

[0081] As illustrated in [Fig.4], the secondary thermally insulating barrier 7 comprises cover plates 47 which are received in counterbores provided in the secondary stop beams 38 and cover the cutouts 43 receiving the stop devices 42. The cover plates 47 ensure the flatness of the support surface of the secondary waterproofing membrane 9.

[0082] In connection with Figures 3, 8 and 9, the secondary thermally insulating barrier 7 and the secondary sealing membrane 9 will now be described in the area of ​​the ceiling wall 4 located between the rear cofferdam wall 82 and the rear transverse edge 49 of the loading / unloading opening 14.

[0083] A corner structure 50 is arranged in the corner at the junction between the ceiling wall 4 and the rear cofferdam wall 82.

[0084] As shown in Figures 2 and 8, the corner structure 50 comprises an X-shaped mechanically welded structure 51 which extends parallel to the edge between the ceiling wall 4 and the rear cofferdam wall 82. The mechanically welded structure comprises two wings 52, 53 which are perpendicular to each other and are each pa connected to one of the ceiling walls 4 and the rear cofferdam 62. Each of the wings 52, 53 is welded to an anchor plate 54, 55 projecting from the upper load-bearing wall 8 or the rear load-bearing wall 56.

[0085] The corner structure 50 of the secondary thermally insulating barrier 7 further comprises insulating elements 57 which are arranged in the zone positioned between the upper load-bearing wall 8, the rear load-bearing wall 56 and the two wings 52, 53 of the mechanically welded structure 5, as well as insulating elements 58, 59 arranged in each zone defined between one of the wings 52, 53 of the mechanically welded structure 51 and one of the upper 8 and rear 56 load-bearing walls.

[0086] As illustrated in [Fig.9], the secondary thermally insulating barrier also comprises, between the corner structure 50 and the arrangement arranged along the rear transverse edge 49 of the loading / unloading opening 14, two rows of insulating panels, aligned in the transverse direction. By convention, the row of insulating panels arranged closest to the rear transverse edge 49 of the loading / unloading opening 14 will be designated as "first row 60" and its insulating panels will be designated as "first insulating panels 62" while that arranged closest to the rear cofferdam wall 82 will be designated as "second row 61" and its insulating panels will be designated as "second insulating panels 63".

[0087] The secondary sealing membrane 9 comprises, in the area arranged between the corner structure 50 and the rear transverse edge 49 of the loading / unloading opening 14, a plurality of strakes 64, visible in [Fig. 8], which extend in the longitudinal direction and are interrupted by the rear transverse edge 49. Each of said strakes 64 is fixed, on the one hand, to one of the wings 53 of the mechanically welded structure 51 and, on the other hand, to the secondary connecting angle iron 19 which runs along the rear transverse edge 49.

[0088] The strakes 64 comprise a central portion 65, flat, resting on the first insulating panels 62 and the second insulating panels 63 and two raised edges 66 arranged on either side of the central portion 65 and projecting towards the inside of the tank relative to the central portion 65.

[0089] The strakes 64 are welded to each other by their raised edges 66. However, in this area, the raised edges 66 of the strakes 64 are not welded to welding supports. In the embodiment illustrated in [Fig.9], the second insulating panels 63 each support three strakes 64: one being arranged in the central part of said second insulating panel 63 while the other two are respectively arranged transversely on either side of said strake 64 and straddling said second insulating panel 63 and one of the adjacent second insulating panels 63.

[0090] The first insulating panels 62 are also devoid of welding supports.

[0091] Thus, in the area between the corner structure 50 and the arrangement arranged along the rear transverse edge 49 of the loading / unloading opening 14, the strakes 64 are not anchored via their raised edges 66 on welding supports. Also, in order to anchor the strakes 64 to these first insulating panels 62 so as to prevent them from being torn off in the event of overpressure in the secondary thermally insulating barrier 7, the first insulating panels 62 are equipped with strake anchoring devices 69, 81 to which each of the central portions 65 of the strakes 64 are welded.This makes it possible to simplify the method of anchoring the strakes 64 in this area and also to simplify the procedure for watertight welding of the strakes 64 together by avoiding the need for a complex weld which could not in any case be carried out by a welding machine, as in the other areas of the membrane, given the excessively short length of the strakes in this area.

[0092] In the embodiment shown, the strake anchoring devices are of two types, one referenced 69 and shown in [Fig. 10] serving only for anchoring the strake while the other referenced 81 and shown in [Fig. 1 1] has a dual functionality since it also serves to ensure the anchoring of the primary insulating panels.

[0093] The strake anchoring device 69 comprises a pin 85 which is intended to pass through an orifice provided in the central portion 65 of one of the strakes 64. The pin 85 comprises a threaded end, not illustrated, which is intended to be screwed into a threaded bore of a metal plate, also not illustrated, which is housed in a recess provided in the internal surface of the first insulating panels 62 and is fixed thereto.

[0094] Furthermore, the pin 85 comprises a collar 86 extending radially relative to the axis of the pin 85. The collar 86 is intended to press the central portion 65 of the strake 64 when the pin 85 is screwed into the threaded bore of the plate fixed to one of the first insulating panels 62. Furthermore, the collar 86 is welded in a sealed manner to the central portion 65 of the strake 64 all around the orifice, which makes it possible to ensure the sealing of the passage of the pin 85 through the secondary sealing membrane 9.

[0095] The strake anchoring device 81, shown in [Fig. 1 1], has a structure similar to that of [Fig. 10] but additionally includes a stud 87 which is intended for fixing the primary insulating panels 13. To do this, the studs 87 project inside a recess provided in the primary insulating panels 13. Furthermore, a support plate, not shown, has a bore threaded onto the stud and a nut, also not shown, which cooperates with a threaded end of the stud so as to ensure the fixing of the support plate to the stud. The plate support plate is supported against a support surface provided in one of the recesses of the primary insulating panel 13 so as to retain it in the direction of the supporting structure. Furthermore, according to an advantageous embodiment, Belleville washers are threaded onto the stud 87, between the nut and the support plate, which makes it possible to ensure elastic anchoring of the primary panels on the secondary thermally insulating barrier.

[0096] Furthermore, returning to Figures 8 and 9, it can be seen that each of the strakes 64 interrupted by the rear transverse edge 49 is anchored to a respective first insulating panel 62. Furthermore, the first insulating panels 62 have a width substantially equal to that of the strakes 64 and the raised edges 66 of said strakes 64 are located substantially in line with the gaps between the adjacent first insulating panels 62.

[0097] It is also observed in Figures 8 and 9 that the second insulating panels 63 are equipped with strake anchoring devices 84, as described above in relation to [Fig. 11], which also provide the function of anchoring the primary insulating panels 13.

[0098] It is also observed in Figures 8 and 9 that the secondary insulating panels 62 of the first row 60 are alternately equipped with strake anchoring devices 69, that is to say those ensuring only the anchoring of the strakes, and with strake anchoring devices 81, those also performing the anchoring function of the primary insulating panels 13. It is also observed that the strake anchoring devices 81 of the first secondary insulating panels 62 as well as those of the second secondary insulating panels 63 are aligned in the longitudinal direction with the primary anchoring devices 29 fixed to the secondary fixing supports 23. Such an alignment is advantageous in that it makes it possible to limit the stresses in the strakes when the tank is cold-pressed.

[0099] It also results from this arrangement that, in the area positioned at the rear of the loading / unloading opening 14, the primary insulating panels are each positioned transversely between two primary anchoring devices 29 fixed to the secondary fixing supports 23.

[0100] Thus, since each first insulating panel 62 is equipped with only a single strake anchoring device 69, the stresses that would be likely to be generated in the secondary sealing membrane 9 by the thermal contraction of the first insulating panels 62 are avoided if several strake anchoring devices 69 were fixed to each first insulating panel 62 and thus moved closer to each other when the tank was cooled.

[0101] Furthermore, as shown in [Fig.2], in the area positioned between the rear cofferdam wall 82 and the rear transverse edge 49, the insulating panels primary 13 are arranged astride a secondary stop beam 38 and insulating elements 58 of the corner structure 50. Such an arrangement is advantageous in that it makes it possible to avoid or at least limit walking phenomena in the support surface of the primary waterproofing membrane 11. In addition, said primary insulating panels 13 have recesses which are provided in their external surface and which each make it possible to house one of the strake anchoring devices 69, described previously.

[0102] With reference to [Fig. 12], a cutaway view of an LNG carrier 70 shows a sealed and insulated 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 barrier intended to be in contact with the LNG contained in the tank, a secondary sealed barrier arranged between the primary sealed barrier and the double hull 72 of the ship, and two insulating barriers arranged respectively between the primary sealed barrier and the secondary sealed barrier and between the secondary sealed barrier and the double hull 72.

[0103] In a manner known per se, loading / unloading pipes 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.

[0104] [Fig. 12] shows 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 88 connected by the underwater pipe 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore installation 77 over a long 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.

[0105] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the onshore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0106] Although the invention has been described in connection with several embodiments by particulars, it is quite 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, as defined by the claims.

[0107] The use of the verb “comprise”, “comprise” or “include” and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

[0108] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. A liquefied gas storage facility comprising a supporting structure (2) and a sealed and thermally insulating tank (71) supported by the supporting structure (2), the supporting structure (2) comprising an upper supporting wall (8) and the tank (71) comprising a ceiling wall (4) which is fixed to the upper supporting wall (8), said ceiling wall (4) comprising, in a thickness direction, from the outside to the inside of the tank, a secondary thermally insulating barrier (7) fixed to the upper supporting wall (8), a secondary sealing membrane (9) resting against the secondary thermally insulating barrier (7), a primary thermally insulating barrier (10) resting against the secondary sealing membrane (9), and a primary sealing membrane (11) resting against the primary thermally insulating barrier (10) and intended to be in contact with the liquefied gas,said ceiling wall (4) being interrupted locally so as to delimit a loading / unloading opening (14) intended to be crossed by loading / unloading pipes, said loading / unloading opening (14) being defined by a front transverse edge (6) and a rear transverse edge (49) parallel to a transverse direction (T) and a first and a second longitudinal edge (5) parallel to a longitudinal direction (L) perpendicular to the transverse direction (T);, the secondary thermally insulating barrier (7) of the ceiling wall (4) comprising a first row (60) of first insulating panels (62), said first insulating panels (62) being aligned in the transverse direction, and arranged between the rear transverse edge (49) and the rear cofferdam wall (82); the secondary sealing membrane (9) of the ceiling wall (4) comprising, between the rear transverse edge (49) and the rear cofferdam wall (82), a plurality of parallel first strakes (64) extending in the longitudinal direction, interrupted by the rear transverse edge (49), each first strake (64) comprising a flat central portion (65) resting against the first insulating panels (62) and two raised edges (66) projecting towards the inside of the tank relative to the central portion (65), the first strakes (64) being juxtaposed in the transverse direction in a repeated pattern and welded together in a sealed manner at the raised edges (66), and wherein the first insulating panels (62) are equipped with strake anchoring devices (69, 81), the flat portion (65) of each of the first strakes (64) being welded to one of the strake anchoring devices (69, 81).

2. A liquefied gas storage facility according to claim 1, wherein each first insulating panel (62) is equipped with a single strake anchoring device (69, 81).

3. A liquefied gas storage facility according to claim 1 or 2, wherein the first insulating panels (62) have a transverse dimension equal to a transverse dimension of the first strakes (64) and are each aligned with one of the first strakes (64) so ​​that the raised edges (66) of the first strakes (64) are located directly above a gap between two adjacent first insulating panels (62).

4. A liquefied gas storage facility according to any one of claims 1 to 3, wherein each strake anchoring device (69, 81) comprises: - a plate fixed to one of the first secondary insulating panels, - a pin (85) fixed to said plate (84) and extending in a thickness direction of the ceiling wall from said plate (84) towards the inside of the tank (71) and passing in a sealed manner through an orifice provided in the flat portion (65) of one of the first strakes (64); said pin (85) comprising a collar (86) fixed in a sealed manner to the first strake (64) around said orifice.

5. A liquefied gas storage facility according to any one of claims 1 to 4, wherein the secondary thermally insulating barrier (7) of the ceiling wall (4) comprises a second row (61) of second insulating panels (63), said second insulating panels (62) being aligned in the transverse direction, and arranged between the first row (60) of first insulating panels (62) and the rear cofferdam wall (82).

6. Storage installation according to claim 5, in which the second insulating panels (62) are equipped with strake anchoring devices (81), the flat portion (65) of at least a part of the first strakes (64) being welded to one of the strake anchoring devices of the second insulating panels (62).

7. A liquefied gas storage facility according to any one of claims 1 to 6, wherein the first strakes (64) are welded along the rear transverse edge (49) to a secondary connecting angle (19) which is connected to the upper load-bearing wall (8).

8. A liquefied gas storage facility according to claim 7, wherein the secondary thermally insulating barrier (7) of the ceiling wall (4) comprises: - at least a first and a second secondary fixing bracket (23) positioned along the rear transverse edge (49); the first and second secondary fixing brackets (23) each comprising a secondary foot (25) which is anchored to the upper load-bearing wall (8), a secondary cap (24) which is welded to the secondary foot (25) and which extends parallel to the longitudinal direction, in a plane parallel to the upper load-bearing wall (8) and a plate (30) which is fixed to the secondary cap (24) by fixing members (31); - at least one secondary edge insulating block (37) which is arranged along the first transverse edge (T), between the first and second secondary fixing brackets (23);and - at least one secondary stop beam (38) which extends along the rear transverse edge (49) and rests at least against the secondary cap (24) of each of the first and second secondary fixing supports (23) and against one of the secondary edge insulating blocks (37), said secondary stop beam (38) being blocked, in the thickness direction of the ceiling wall, between the plate (30) and the secondary cap (24) of each of the first and second secondary fixing supports; the secondary connecting angle (19) comprising a first wing (20) which rests against the secondary stop beam (38) and a second wing (21) which is connected to the upper load-bearing wall (8).;

9. A liquefied gas storage facility according to claim 8, wherein the first and second secondary fixing supports carry a primary anchoring device (29) intended to ensure anchoring of the primary thermally insulating barrier (10) and wherein some of the strake anchoring devices (69, 81) which equip the first insulating panels (62) are aligned in the longitudinal direction L with the primary anchoring device (29).

10. A liquefied gas storage facility according to claim 8 or 9, wherein the primary thermally insulating barrier of the ceiling wall (4) comprises, in an area positioned between the rear cofferdam wall (82) and the rear transverse edge (49), primary insulating panels (13) which are arranged astride the secondary stop beam (38) and insulating elements (58) of a corner structure (50) which is arranged at the junction between the ceiling wall (4) and the rear cofferdam wall (82).

11. A liquefied gas storage facility according to claim 10, wherein the primary insulating panels (13) of the area positioned between the rear cofferdam wall (82) and the rear transverse edge (49) comprise recesses, receiving the strake anchoring devices (69, 81).

12. A liquefied gas storage facility according to any one of claims 1 to 11, wherein the first strakes (64) are welded to a mechanically welded structure (51) which runs along an edge between the ceiling wall (4) and the rear cofferdam wall (82) and which is fixed to the ceiling wall (4) and to the rear cofferdam wall (82).

13. A vessel (70) for transporting a liquefied gas, the vessel comprising a liquefied gas storage facility according to any one of claims 1 to 12.

14. A transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 13 and 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).

15. A method of loading or unloading a ship (70), in which a liquefied gas is conveyed through insulated pipes (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) according to claim 13.

Images