Sealed and thermally insulating structure

Abstract

The invention relates to a structure comprising: a first sealed wall (3) and a second sealed wall (2) situated at a distance from the first sealed wall (3), an intermediate space (4) arranged between the first sealed wall (3) and the second sealed wall (2), wherein the intermediate space (4) comprises: a porous separator (5); an extraction zone (7) situated between the porous separator (5) and the second sealed wall (2), a granular zone (14) situated between the porous separator (5) and the first sealed wall (3), the granular zone (14) being filled with a granular insulating packing, wherein the porous separator has pores of a size smaller than a particle size of the granular insulating packing, wherein the extraction zone has a resistance to the passage of the gaseous molecules lower than a resistance to the passage of the gaseous molecules of the granular zone.

Description

Waterproof and thermally insulating structure

[0001] The invention relates to the field of sealed and thermally insulating structures for the storage and / or transport of low-temperature liquefied gas, such as a tank for the transport of liquid hydrogen, which is at approximately -253°C at atmospheric pressure but which can also be stored under higher pressure. These tanks can be installed in a fixed position or on any land or floating vehicle. Technological background

[0002] Self-supporting tanks and membrane tanks are known for the storage and / or transport of liquefied gas.

[0003] In order to keep the gas in liquid form inside the tank, it is important that the tank has excellent thermal insulation properties, in particular to limit the evaporation of the liquefied gas contained inside the tank.

[0004] For example, a tank has a double wall insulated with a granular insulating lining, such as perlite or glass microspheres. In such a tank, the granular insulating lining fills the entire space between the double wall.

[0005] It is known, for example, in the document "Glassbubblesinsulation forliquidhydrogenstoragetanks, JPSass, WW St. Cyr, TM Barrett, RG Baumgartner, JWLott,and JEFesmirel, June 30, 2009" to reduce the pressure in the intermediate space of the double wall containing the granular insulating lining, here glass microspheres, in order to improve the thermal insulation properties of the tank.

[0006] However, the process of evacuating such an intermediate space using vacuum pumps is a long and energy-consuming process due to the significant pressure losses generated by the granular insulating lining. In other words, it is difficult to extract all the air initially present in the intermediate space. As an illustration, for a type C tank (as defined by the IGC code of the International Maritime Organization) whose intermediate space has a volume of 3500 m 3 filled with perlite, it takes 125 days of pumping to reach a pressure of 6 Pa in this space.

[0007] One idea behind the invention is to solve the above-mentioned problems.

[0008] Another idea behind the invention is to propose a sealed structure comprising an intermediate space comprising a gaseous phase under vacuum in order to obtain excellent thermal insulation properties.

[0009] Another idea behind the invention is to propose a waterproof and thermally insulating structure having an intermediate space which can be evacuated in an accelerated manner.

[0010] An idea underlying the invention is to propose a vacuum method for vacuuming an intermediate space of a sealed and thermally insulating structure, and in particular the vacuuming of which is accelerated compared to currently known vacuum methods.

[0011] According to one embodiment, the invention provides a sealed and thermally insulating structure for storing or transporting a liquefied gas, the structure comprising:a first sealed wall and a second sealed wall located at a distance from the first sealed wall,a thermally insulating intermediate space arranged between the first sealed wall and the second sealed wall, the intermediate space being capable and intended to be placed under vacuum,in which the intermediate space comprises:a first porous separator;a first extraction zone located between the first porous separator and the second sealed wall,a granular zone located between the first porous separator and the first sealed wall, the granular zone being filled with a granular thermally insulating lining,in which the first porous separator has pores having a dimension smaller than a granulometry of the granular insulating lining to retain the granular thermally insulating lining in the granular zone,in which the first extraction zone has a resistance to the passage of gas molecules less than a resistance to the passage of gas molecules of the granular zone.;

[0012] In other words, the first extraction zone has a lower resistance to the flow of gas molecules than the intermediate space would have if it were completely filled with the granular thermally insulating lining and without any extraction zone.

[0013] Thanks to these characteristics, the structure has excellent thermal insulation properties. In addition, thanks to such a first extraction zone, the pressure losses in the intermediate space are reduced, which allows for faster vacuuming. The gas phase of the intermediate space can thus be evacuated and pumped via a vacuum pump which is advantageously connected to the first extraction zone. Such a structure makes it possible to considerably reduce the pumping time required for vacuuming, going from several months in the prior art to a few days with the present invention.

[0014] According to the invention, the term “granulometry” means the average size of the grains of the granular insulating lining, i.e. their average equivalent diameter. Thus, the term “pore dimension less than a granulometry of the granular insulating lining” means that the pores of the porous separator must have dimensions, for example an average equivalent diameter, less than the average equivalent diameter of the particles, which makes it possible to prevent the passage of the granular insulating lining through the porous separator, towards the extraction zone.

[0015] According to embodiments, such a structure may comprise one or more of the following features.

[0016] According to one embodiment, the first extraction zone comprises a first porous insulating layer, and the first porous insulating layer has open and interconnected pores having a dimension greater than the dimension of the open pores of the granular thermally insulating lining and the first porous insulating layer has a porosity greater than a porosity of the granular thermally insulating lining. Thus, the pressure losses in the intermediate space are reduced, which allows for faster vacuuming.

[0017] According to one embodiment, the first extraction zone does not comprise any thermally insulating material. That is to say, the first extraction zone is not filled with material increasing the resistance to the passage of gas molecules except for possible means of fixing the first porous separator.

[0018] According to one embodiment, the thickness of the extraction zone is at least 1 mm, preferably at least 10 mm and even more preferably at least 100 mm, for example between 100 mm and 500 mm.

[0019] According to one embodiment, the extraction zone has an open porosity greater than 96%.

[0020] According to one embodiment, the extraction zone has a Knudsen number (Kn) lower than the Knudsen number of the granular zone.

[0021] According to one embodiment, the extraction zone has a Kn less than or equal to 0.5, preferably less than 0.1, at 296 Kelvin (K), for a gas, at the target pressure. According to one embodiment, the extraction zone has a Kn less than or equal to 0.5, preferably less than 0.1, at 296 Kelvin (K), for nitrogen, at a pressure of between 10 and 200 Pa.

[0022] According to one embodiment, the granular insulating lining has grains whose average equivalent diameter is greater than 110% of the average equivalent diameter of the pores of the porous separator.

[0023] According to one embodiment, the porous separator has a porosity dimension allowing clogging of the porous separator by the granular insulating lining with a cut-off threshold of less than 90%, preferably less than 75%, and even more preferably less than 50%, of the average diameter of the grains of the granular thermally insulating lining.

[0024] According to another embodiment, the porous separator has a cut-off threshold of less than 50µm (micrometers) and preferably less than 15µm.

[0025] According to one embodiment, the intermediate space comprises a second porous separator spaced from the first sealed wall, and a second extraction zone located between the second porous separator and the first sealed wall, the granular zone being located between the first porous separator and the second porous separator, in which the second porous separator has pores having a dimension smaller than the particle size of the granular insulating lining, in which the second extraction zone has a resistance to the passage of gaseous molecules lower than a resistance to the passage of gaseous molecules of the granular zone.

[0026] In one embodiment, the second extraction zone comprises a second porous insulating layer, and the second porous insulating layer has open and interconnected pores having a dimension greater than the dimension of the open pores of the granular thermally insulating liner and the second porous insulating layer has a porosity greater than a porosity of the granular thermally insulating liner.

[0027] According to one embodiment, the second extraction zone does not comprise any thermally insulating material. That is to say, the second extraction zone is not filled with material increasing the resistance to the passage of gas molecules except for possible means of fixing the second porous separator.

[0028] According to one embodiment, the first porous separator comprises a sheet perforated throughout, an expanded metal sheet, a metal mesh, a plate of composite material perforated throughout, or a plate of composite material based on fibers bonded together and with open porosity greater than 30% of its volume.

[0029] According to one embodiment, the second porous separator comprises a sheet perforated throughout, an expanded metal sheet, a metal mesh, a plate of composite material perforated throughout, or a plate of composite material based on fibers bonded together and with open porosity greater than 30% of its volume.

[0030] According to one embodiment, the first porous separator or the second porous separator is fixed to one of the first and second sealed walls via fixing means. According to one embodiment, the fixing means are chosen from bolts and rivets.

[0031] According to one embodiment, the first porous separator comprises a rigid screen attached to one of the first and second sealed walls.

[0032] According to one embodiment, the second porous separator comprises a rigid screen attached to one of the first and second sealed walls.

[0033] According to one embodiment, the sieve is a sheet perforated throughout, an expanded metal sheet, a metal mesh, a composite material plate perforated throughout, or a composite material plate based on fibers bonded together and with open porosity greater than 30% of its volume.

[0034] According to one embodiment, the first porous separator or the second porous separator comprises a plurality of screens.

[0035] According to one embodiment, the screens of the plurality of screens each have a central portion and two lateral portions projecting from each end of the central portion, towards the first wall or the second wall. According to one embodiment, the two lateral portions project perpendicular to the central portion.

[0036] According to one embodiment, the first porous separator comprises a textile covering the screen and fixed to said screen, the textile having pores having a dimension smaller than the particle size of the granular insulating lining.

[0037] According to one embodiment, the second porous separator comprises a textile covering the screen and fixed to said screen, the textile having pores having a dimension smaller than the particle size of the granular insulating lining.

[0038] According to one embodiment, the textile is attached to the screen via fastening means. According to one embodiment, the fastening means are chosen from an adhesive strip, such as a Velcro® type strip, glue, rivets, bolts and sewn threads.

[0039] According to one embodiment, the textile is chosen from:- a fabric based on Polyethylene terephthalate (PET) fibers, mineral fibers such as glass and metal fibers;- paper based on mineral fibers;- a veil or felt made of non-woven fibers based on polymer fibers, such as PET or polypropylene, or based on mineral fibers such as fiberglass.

[0040] According to one embodiment, the textile has a filtration threshold of less than 30µm, and more preferably less than 15µm.

[0041] According to one embodiment, the first insulating layer comprises glass wool.

[0042] According to one embodiment, the second insulating layer comprises glass wool.

[0043] According to one embodiment, the glass wool has a pore size of between 0.5 mm and 2 mm.

[0044] According to one embodiment, the glass wool has a porosity rate of between 98% and 99.5%.

[0045] According to one embodiment, the granular thermally insulating lining is selected from perlite, hollow glass microspheres, fumed silicas, granular aerogels, such as silica aerogels or a mixture of at least two of these materials.

[0046] According to one embodiment, the granular thermally insulating lining has an open porosity rate of less than 97% or less than 75% or less than 45%.

[0047] According to one embodiment, the granular aerogel has an open porosity rate of between 94% and 97%.

[0048] According to one embodiment, the perlite has an open porosity rate of between 75% and 97%.

[0049] According to one embodiment, the pyrogenic silica has an open porosity rate of between 94% and 97%.

[0050] According to one embodiment, the glass microspheres have an open porosity rate of between 30% and 45%.

[0051] According to one embodiment, the granular thermally insulating lining has a particle size of less than 4000 µm, preferably less than 2000 µm.

[0052] According to one embodiment, the perlite has a particle size greater than 50 µm, for example a particle size between 500 and 1500 µm.

[0053] According to one embodiment, the granular aerogel has a particle size greater than 50 µm, for example an average diameter of between 1000 and 2000 µm.

[0054] According to one embodiment, the hollow glass microspheres have a diameter greater than 30 µm and whose average diameter is 65 µm. For example, the reference K1 from the company 3M, 90% of which has a diameter greater than 30 µm and whose average size is 65 µm, can be used.

[0055] According to one embodiment, the pyrogenic silica has agglomerates greater than 200 µm.

[0056] According to one embodiment, the structure comprises a vacuum pump connected to the first extraction zone.

[0057] According to one embodiment, the structure comprises a vacuum pump connected to the second extraction zone.

[0058] According to one embodiment, the intermediate space has a gas phase at an absolute pressure of less than 10 Pa, preferably less than 1 Pa when the structure is filled with liquefied gas.

[0059] The pressure indicated above is the final pressure required once the internal space defined by the first sealed wall is filled with liquefied gas. This pressure is achieved by a combination of the continuous action of the vacuum pump and cryopumping of part of the residual gases onto the cold wall.

[0060] According to one embodiment, the first sealed wall is intended to be in contact with the liquefied gas and the second sealed wall is arranged outside the first sealed wall.

[0061] According to one embodiment, the structure is in the form of a tank intended to store liquefied gas.

[0062] According to one embodiment, the tank is a self-supporting tank.

[0063] According to one embodiment of the self-supporting tank, the second sealed wall and the first sealed wall are self-supporting, the second sealed wall and the first sealed wall being carried by a supporting member, said supporting member passing through the second sealed wall in order to carry the first sealed wall.

[0064] According to another embodiment, the tank is a membrane tank, the second sealed wall being a supporting structure and the first sealed wall is a sealed membrane carried by a plurality of support elements positioned in the intermediate space and extending between the second sealed wall and the first sealed wall.

[0065] According to one embodiment, the plurality of support members comprises load-bearing pillars.

[0066] According to one embodiment, the structure is in the form of a pipeline intended to transport liquefied gas.

[0067] According to an embodiment of the structure in the form of a pipe, the first sealed wall and the second sealed wall extend in a longitudinal direction of the structure, the first sealed wall forming an internal space intended to be in contact with the liquefied gas, said internal space comprising a through hole extending in the longitudinal direction of the structure, from a first longitudinal end of the structure to a second longitudinal end of the structure in order to allow the transport of a liquefied gas.

[0068] According to one embodiment, the gas phase of the intermediate space is at an absolute pressure of less than 300 Pa and preferably 100 Pa before cooling and filling of the internal space with liquefied gas.

[0069] This is the maximum pressure defined at room temperature before the inner tank is cooled and filled with liquid gas. This pressure allows granular insulating pads to see their thermal conductivity drop by -50% to -90% of their initial conductivity when placed in an insulation space atmosphere of 1.10 5 Pa. This drop in conductivity thus makes it possible to initiate cooling and filling with liquefied gas with limited rates of evaporation of this liquefied gas induced by the cooling of the tank.

[0070] According to one embodiment, the liquefied gas is chosen from: liquefied natural gas (LNG), helium, oxygen (LOx), argon and preferably hydrogen (LH2).

[0071] According to one embodiment, the invention also provides a method for placing a sealed and thermally insulating structure under vacuum for storing or transporting a liquefied gas, said method comprising:- providing a sealed and thermally insulating structure for storing or transporting a liquefied gas, the structure comprising: a first sealed wall, the first sealed wall forming an internal space intended to be in contact with the liquefied gas; a second sealed wall located at a distance from the first sealed wall, a thermally insulating intermediate space arranged between the first sealed wall and the second sealed wall, in which the intermediate space has a gas phase and comprises: a first porous separator;a first extraction zone located between the first porous separator and the second sealed wall,a granular zone located between the first porous separator and the first sealed wall, the granular zone being filled with a granular thermally insulating lining,in which the first porous separator has pores having a dimension smaller than a granulometry of the granular insulating lining to retain the granular thermally insulating lining in the granular zone;and in which the first extraction zone has a resistance to the passage of gas molecules less than a resistance to the passage of gas molecules of the granular zone;and- lowering the pressure in the intermediate space by means of a vacuum pump connected to the first extraction zone until the gas phase of the intermediate space has an absolute pressure of less than 200 Pa and preferably 50 Pa and more preferably less than 10 Pa before cooling and filling the internal space with the liquefied gas.;

[0072] According to one embodiment of the method, the structure comprises a second extraction zone as mentioned above and the method further comprises: lowering the pressure in the intermediate space by means of a vacuum pump opening into the second extraction zone until the gas phase of the intermediate space has an absolute pressure of less than 200 Pa, preferably 100 Pa before cooling and filling the internal space with the liquefied gas in order to obtain a structure as mentioned above.

[0073] According to one embodiment of the method, the pressure is lowered in the intermediate space to a pressure lower than 50 Pa and preferably to 10 Pa.

[0074] According to an advantageous embodiment of the method, a cryopumping phenomenon is used, as a complement to the aforementioned vacuum pump, to obtain the target depression level in the intermediate space.

[0075] According to one embodiment of the method, prior to its being placed under vacuum, the intermediate space is charged with an inert gas having a solid condensation temperature higher than the liquefaction temperature of the liquefied gas stored in the structure. For example, when the liquefied gas stored in the tank is liquid hydrogen, the inert gas may be carbon dioxide. Thus, given the temperature of the hydrogen in the liquid state, the carbon dioxide contained in the intermediate space condenses in the solid state in the intermediate space, which contributes to reducing the pressure therein.

[0076] According to one embodiment, the invention also provides a ship for transporting a liquefied gas, the ship comprising a structure as mentioned above.

[0077] According to one embodiment, the invention also provides a transfer system for transferring liquefied gas, the system comprises a aforementioned vessel, insulated pipes arranged to connect the structure installed in the hull of the vessel to a floating or land-based storage facility and a pump for driving liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the structure of the vessel.

[0078] According to one embodiment, the invention also provides a method of loading or unloading a ship as mentioned above, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the structure of the ship.

[0079] According to one embodiment, the transfer system for transferring liquefied gas or the loading or unloading method in which at least one of the insulated pipes is a structure in the form of a pipe as mentioned above. Brief description of the figures

[0080] The invention will be better understood, and other objects, 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 accompanying drawings.

[0081] This is a cutaway view of a self-supporting structure according to one embodiment.

[0082] This is a sectional view of a structure according to another embodiment having the shape of a membrane tank.

[0083] This is a sectional view along an axis perpendicular to the longitudinal direction of a structure according to another embodiment having the shape of a pipeline.

[0084] This is a schematic cutaway representation of a ship structure and a loading / unloading terminal for this structure.

[0085] This is an enlarged, sectional view of zone I illustrated in the, according to one embodiment.

[0086] Illustrates a top view of the embodiment of the.

[0087] This is an enlarged, sectional view of zone I shown in the, according to another embodiment.

[0088] Illustrates a top view of the embodiment of the.

[0089] This is an enlarged, sectional view of zone I shown in the, according to another embodiment.

[0090] A first embodiment is illustrated with the and represents a sealed and thermally insulating structure 1 for the storage of a liquefied gas. The structure has the form of a self-supporting tank.

[0091] The structure 1 comprises a first sealed wall 3, a second sealed wall 2 and a porous separator 5 located between the first sealed wall 3 and the second sealed wall 2. The second sealed wall 2 is located outside the first sealed wall 3

[0092] The first sealed wall 3 is located at a distance from an interior surface 22 of the second sealed wall 2. The first sealed wall 3 has an interior surface 32 defining an internal space 9 intended to store the liquefied gas, such as liquid hydrogen.

[0093] The first sealed wall 3 has an outer surface 31 defining with the inner surface 22 of the outer sealed wall 2 an intermediate space 4 thermally insulating under vacuum.

[0094] The second watertight wall 2 and the first watertight wall 3 are self-supporting, that is to say they are rigid and they compensate their weight by an opposing force to hold themselves. The second watertight wall 2 and the first watertight wall 3 are carried by supporting members 6, for example by beams. The supporting member 6 comprises a spacer 61 passing through the intermediate space 4 in order to carry the first watertight wall 3.

[0095] The intermediate space 4 comprises the porous separator 5 which is spaced from the inner surface 22 of the second sealed wall 2 and fixed to the second sealed wall 2. The method of fixing the porous separator will be detailed later.

[0096] The porous separator comprises, for example, a sieve, a textile or a combination of a sieve and a textile.

[0097] The intermediate space 4 further comprises an extraction zone 7 located between the first porous separator 5 and the inner surface 22 of the second sealed wall 2. The extraction zone 7 is intended to be drawn into a vacuum via a vacuum pump, not illustrated, in order to place the entire intermediate space 4 under vacuum. The extraction zone 7 is for this purpose connected to the vacuum pump by a pipe 17, as shown in the figure.

[0098] The intermediate space 4 comprises a granular zone 14 located between the porous separator 5 and the outer surface 31 of the inner sealed wall 3, the granular zone 14 is filled with a granular thermally insulating lining, for example perlite, hollow glass microspheres, pyrogenic silicas, silica aerogels or a mixture of at least two of these examples.

[0099] The extraction zone 7 comprises a layer of porous thermal insulation, for example a layer of glass wool, arranged between the porous separator 5 and the inner surface 22 of the second sealed wall 3.

[0100] The porous separator 5 has pores of a dimension smaller than the granulometry of the granular insulating lining in order to retain the granular thermally insulating lining in the granular zone 14.

[0101] In a variant not shown similar to the, the intermediate space 14 of the comprises a second porous separator spaced from the outer surface 31 of the first sealed wall 3 and fixed to the first sealed wall 3, and a second extraction zone located between the second porous separator and the outer surface 31 of the first sealed wall 3. The granular zone 14 is located between the porous separator 5 and the second porous separator, the second extraction zone comprises a second porous insulating layer, retained between the second porous separator and the outer surface 31 of the first sealed wall 3. The second porous separator has, in a manner similar to the porous separator 5, a pore size smaller than the grain size of the granular insulating lining while the second porous insulating layer has pores having a size larger than the grain size of the granular insulating lining.

[0102] Advantageously, the thickness of the extraction zones is at least 1 mm, preferably at least 10 mm and even more preferably at least 100 mm.

[0103] According to a variant not shown, the extraction zone does not include thermally insulating material.

[0104] For the other embodiments shown with Figures 2 and 5 to 9, identical or similar elements bear the same reference numbers as those described with, increased by 100. They will only be described to the extent that they differ from those previously described.

[0105] In the embodiment illustrated in the, the structure has the shape of a membrane tank, for example having a polyhedral shape.

[0106] The first watertight wall 103 of the structure 101 is a watertight membrane, for example a corrugated metal membrane or a metal membrane comprising a continuous sheet of strakes. The watertight membrane is carried by a plurality of support elements (not shown), for example load-bearing pillars positioned in the intermediate space 104 and extending between the second watertight wall 102 and the first watertight wall 103.

[0107] The metal membrane is, for example, made of Invar ®, i.e. an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 -6 and 2.10 -6 K -1 .

[0108] According to a variant, the second wall 102 is a sealed membrane. In this case, the first sealed wall 103 is a primary sealed membrane, that is to say intended to be in contact with the liquefied gas contained in the internal space 109, and the second wall is a secondary sealed membrane.

[0109] According to one variant, the structure comprises a plurality of additional walls in order to form a multi-layer structure, such as a membrane tank incorporating one or more embodiments described previously.

[0110] In a variant not shown similar to the, the intermediate space 104 of the comprises a second porous separator spaced from the outer surface 131 of the first sealed wall 103 and fixed to the first sealed wall 103, and a second extraction zone located between the second porous separator and the outer surface 131 of the first sealed wall 103. The granular zone 114 is located between the porous separator 105 and the second porous separator, the second extraction zone comprises a second porous insulating layer, retained between the second porous separator and the outer surface 31 of the first sealed wall 3. The second porous separator having, in a manner similar to the porous separator 105, a pore size smaller than the particle size of the granular insulating lining.

[0111] According to another embodiment, the structure 201 illustrated in the figure has the shape of a cylindrical pipe intended to transport a liquefied gas.

[0112] According to this variant, the first sealed wall 203, the second sealed wall 202 and the internal space 209 extend in a longitudinal direction of the structure 201, the internal space 209 comprising a through hole extending in the longitudinal direction of the structure 201 from a first longitudinal end of the structure 201 to a second longitudinal end of the structure 201. The through hole makes it possible to transport a liquefied gas from the first longitudinal end of the structure 201 to the second longitudinal end of the structure 201 and vice versa.

[0113] The intermediate space 214 of the structure 201 further comprises a second porous separator 215 spaced from the outer surface 231 of the first sealed wall 203 and fixed to the first sealed wall 203. A second extraction zone 207 is located between the second porous separator 215 and the outer surface 231 of the first sealed wall 203.

[0114] The granular zone 214 is located between the first porous separator 205 and the second porous separator 215.

[0115] In a manner similar to that described above, the second extraction zone 207 comprises a second porous insulating layer retained between the second porous separator 215 and the outer surface 231 of the first sealed wall 203 and the size of the pores of the second porous separator 215 is smaller than the particle size of the granular insulating lining.

[0116] In a variant not shown similar to the, the structure 201 comprises a single porous separator, namely the porous separator 205 which is fixed to the second sealed wall 202.

[0117] Different embodiments of the porous separator 5 are described below with figures 5 to 9.

[0118] The porous separator 5 as illustrated in Figures 5 and 6 comprises a rigid screen having a central part 51 located at a distance and parallel to the second sealed wall 2 as well as at least two lateral parts 52 projecting perpendicularly from the central part 51, in the direction of the second sealed wall 2 and having one end resting on the second sealed wall 2. The porous separator 5 is fixed to the second sealed wall 2 via fixing means 53, such as a bolt or a rivet fixed to the second sealed wall 2.

[0119] When a plurality of small sieves are juxtaposed with each other, a single central fixing per sieve is sufficient, as illustrated in the.

[0120] The space between each sieve has a dimension that does not allow the granular thermally insulating lining to pass through.

[0121] According to a variant of the porous separator 5 illustrated with figures 7 and 8, the porous separator 5 does not have lateral parts resting against the second sealed wall 2 as is the case on the. In this embodiment, the porous separator 5 is fixed to the second sealed wall 2 via supporting fixing means 153 located for example at the four corners of each sieve. The fixing means 153 each have for example an anchoring rod anchored on the second sealed wall 2 and two fixing washers sandwiching the porous separator 5 allowing both to fix the sieve and to keep it at a distance from the second sealed wall 2. According to an alternative embodiment presented with the, the porous separator 5 comprises a textile 54 covering the sieve and fixed to said sieve. The textile is fixed to the sieve for example via an adhesive strip located between the sieve and the textile.When several textiles 54 are used, the textiles are fixed together for example by sewing.

[0122] A method for evacuating an intermediate space of a structure according to one embodiment will be described below, in connection with the.

[0123] The management of the gas phase of the intermediate space 104 is carried out via a gas management installation 110.

[0124] The gas management installation 110 comprises a suction line 42 connected to a vacuum pump 43 and opening into the extraction zone 107. Pressure sensors (not shown) are arranged in the extraction zone 107 and in the granular zone 114.

[0125] In order to evacuate the intermediate space 104, the vacuum pump is activated until the gas phase of the intermediate space 104 reaches an absolute pressure of less than 300 Pa and preferably 100 Pa before cooling and filling the internal space with the liquefied gas.

[0126] In order to manage the gaseous phase present in the intermediate space 104, the gas management installation 110 may further comprise a supply line 40 connected to a gas source 41 and to a compressor 50 and opening into the extraction zone 107. Such a gas management installation may be useful for carrying out internal gas monitoring or sweeping of the intermediate space 104.

[0127] The gas management installation 110 may further comprise various elements making it possible to configure and monitor the injection and / or suction of gas as shown in the.

[0128] For example, the gas management installation 110 comprises one or more devices chosen from: - a gas analyzer 44 extracted via the suction line 42, - a gas outlet flow meter 45; a gas inlet flow meter 46, - a control unit 47, - a temperature sensor 49 located in the intermediate space 104.

[0129] In a variant of the method not shown, the gas management installation 110 further comprises a second suction line (not shown) connected to the vacuum pump 43 or another vacuum pump and opening into a second extraction zone as described previously, for example for such a method applied to the second embodiment illustrated in the, the second suction line opens into the second extraction zone 207.

[0130] Such a configuration with suction in the first extraction zone and in the second extraction zone has the advantage of further accelerating the vacuuming of the intermediate space and more precisely of the granular zone 214 which is filled with granular thermally insulating lining and can thus be difficult and time-consuming to vacuumize.

[0131] Similarly, in order to manage the gaseous phase present in the intermediate space 104, the gas management installation 110 may further comprise a supply line 40 connected to a gas source 41 and to a compressor 50 and opening into the second extraction zone, for example the second extraction zone 207 for the embodiment illustrated in the.

[0132] The different variants of this method can be adapted and applied in a manner analogous to the embodiments previously described.

[0133] With reference to the, a cutaway view of a hydrogen vessel 70 shows a tank-shaped, sealed and insulated structure 71 of generally prismatic shape mounted in the double hull 72 of the vessel. The wall of the structure 71 comprises a primary sealed barrier intended to be in contact with the liquid hydrogen (LH2) contained in the structure, a secondary sealed barrier arranged between the primary sealed barrier and the double hull 72 of the vessel, 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.

[0134] 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 hydrogen from or to the structure 71.

[0135] The 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 the hydrogenerator. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the hydrogen carrier 70 to be loaded and unloaded 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 over a long distance, for example 5 km, which makes it possible to keep the hydrogen carrier 70 at a great distance from the coast during loading and unloading operations.

[0136] 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.

[0137] 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 technical equivalents of the means described as well as their combinations if these fall within the scope of the invention. For example, the first sealed wall and the second sealed wall are interchangeable.

[0138] 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.

[0139] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

A sealed and thermally insulating structure for storing or transporting a liquefied gas chosen from: liquefied natural gas, helium, oxygen, argon and hydrogen, the structure (1, 101, 201) comprising: a first sealed wall (3, 103, 203) and a second sealed wall (2, 102, 202) located at a distance from the first sealed wall (3, 103, 203), a thermally insulating intermediate space (4, 104, 204) arranged between the first sealed wall (3, 103, 203) and the second sealed wall (2, 102, 202), the intermediate space (4, 104, 204) being suitable and intended to be placed under vacuum, in which the intermediate space (4, 104, 204) comprises: a first porous separator (5, 105, 205); a first extraction zone (7, 107, 207) located between the first porous separator (5, 105, 205) and the second sealed wall (2, 102, 202), a granular zone (14, 114, 214) located between the first porous separator (5, 105, 205) and the first sealed wall (3, 103,203), the granular zone (14, 114, 214) being filled with a granular thermally insulating lining, wherein the first porous separator (5, 105, 205) has pores having a dimension smaller than a particle size of the granular thermally insulating lining to retain the granular thermally insulating lining in the granular zone (14, 114, 214), wherein the first extraction zone (7, 107, 207) has a resistance to the passage of gas molecules lower than a resistance to the passage of gas molecules of the granular zone (14, 114, 214), wherein the first extraction zone (7, 107, 207) comprises a first porous insulating layer,and wherein the first porous insulating layer has open and interconnected pores having a dimension greater than the dimension of the open pores of the granular thermally insulating liner and the first porous insulating layer has a porosity greater than a porosity of the granular thermally insulating liner, wherein the first porous separator (5, 105, 205) comprises a rigid screen attached to one of the first and second sealed walls., The structure of claim 1, wherein the intermediate space (204) comprises a second porous separator (215) spaced from the first sealed wall (203), and a second extraction zone (207) located between the second porous separator (215) and the first sealed wall (203), the granular zone (214) being located between the first porous separator (205) and the second porous separator (215), wherein the second porous separator (215) has pores having a dimension smaller than the particle size of the granular insulating lining, wherein the second extraction zone (207) has a resistance to the passage of gaseous molecules less than a resistance to the passage of gaseous molecules of the granular zone (14, 114, 214). The structure of claim 2, wherein the second extraction zone comprises a second porous insulating layer, and wherein the second porous insulating layer has open and interconnected pores having a dimension greater than the dimension of the open pores of the granular thermally insulating liner and the second porous insulating layer has a porosity greater than a porosity of the granular thermally insulating liner. The structure of claim 1, wherein the first porous separator (5, 105, 205) comprises a textile covering the screen and attached to said screen, the textile having pores having a dimension smaller than the particle size of the granular insulating lining. Structure according to one of claims 1 to 4, in which the granular thermally insulating lining has a particle size of less than 4000µm and preferably less than 2000µm. Structure according to one of claims 1 to 5, comprising a vacuum pump (43) connected to the first extraction zone (7, 107, 207). Structure according to one of claims 1 to 6, in which the intermediate space has a gas phase at an absolute pressure of less than 300 Pa. Structure according to one of claims 1 to 7, in which the granular insulating filling is chosen from perlite, hollow glass microspheres, fumed silica and silica aerogels. Structure according to one of claims 1 to 8, in which the first porous insulating layer comprises glass wool. Structure according to one of claims 1 to 9, in which the first porous separator (5, 105, 205) is chosen from a sheet perforated throughout, an expanded metal sheet, a metal mesh, a plate of composite material perforated throughout, a plate of composite material based on fibers bonded together and with open porosity greater than 30% of its volume. Structure according to any one of claims 1 to 10, in which the first sealed wall (3, 103, 203) is intended to be in contact with the liquefied gas and the second sealed wall (2, 102, 202) is arranged outside the first sealed wall (3, 103, 203). Structure according to one of claims 1 to 11, the structure being in the form of a tank intended to store liquefied gas. Structure according to one of claims 1 to 12, the structure being in the form of a pipeline intended to transport a liquefied gas. Method for placing a sealed and thermally insulating structure under vacuum for the storage or transport of a liquefied gas, said method comprising:- providing a structure according to one of claims 1 to 13, and- lowering the pressure in the intermediate space (14, 114, 214) by means of a vacuum pump (43) connected to the first extraction zone (7, 107, 207) until the gas phase of the intermediate space (4, 104, 204) has an absolute pressure of less than 200 Pa and preferably 100 Pa before cooling and filling the internal space of the sealed structure with the liquefied gas. A vessel (70) for transporting a liquefied gas, the vessel comprising a structure (71) according to any one of claims 1 to 13. A transfer system for transferring liquefied gas, the system comprising a vessel (70) according to claim 15, insulated pipes (73, 79, 76, 81) arranged to connect the structure (71) installed in the hull of the vessel to a floating or land-based storage facility (77) and a pump for driving liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the structure of the vessel. A method of loading or unloading a ship (70) according to claim 15, wherein 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 structure (71) of the ship (70).

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