Sealed insulated tank and associated vacuum drawing method

Abstract

The present invention relates to a tank having an intermediate space and a method for evacuating the intermediate space in a sealed, insulated tank (1), the intermediate space (30) containing a gas phase, the gas phase being composed of one or more main chemical species and possibly one or more residual chemical species, the main chemical species exhibiting a saturation vapor pressure at any temperature below 126 K lower than the saturation vapor pressure of nitrogen at said temperature below 126 K, the pressure in the intermediate space (30) being lower in absolute value than a pressure threshold, the pressure threshold being lower than the triple point of the main chemical species, and the residual chemical species having a partial pressure lower than 0.1 kPa.

Description

[Technical field]

[0001] The invention relates to the field of sealed, insulated tanks for the storage and / or transportation of liquefied gases at low temperatures, such as tanks for liquid hydrogen, which at atmospheric pressure is about -253°C, but can also be stored at higher pressures. These tanks can be installed at fixed stations or on land or floating vehicles. [Background technology]

[0002] Onshore freestanding tanks are known for the storage and / or transportation of liquefied gases at atmospheric pressure.

[0003] Also known are membrane tanks for storing and / or transporting liquefied natural gas at atmospheric pressure, which successively comprise, for example in the thickness direction from the inside to the outside of the tank, a primary sealing membrane intended to be in contact with the liquefied natural gas, a primary insulating barrier, a secondary sealing membrane, a secondary insulating barrier and a load-bearing structure which defines the general type of the tank.

[0004] The primary and secondary sealing membranes define a primary space therebetween that contains the primary insulating barrier.

[0005] In order to keep the gas in the tank in a liquid state, it is important that the tank has good insulating properties: indeed, such a tank limits as much as possible the heating of the liquefied gas contained in the tank and therefore the transfer of heat to the outside of the tank, which could damage elements sensitive to low temperatures.

[0006] For example, as described in the paper "Glass Bubbles Insulation for Liquid Hydrogen Storage Tanks" by JPSass, WWSt.Cyr, TMBarrett, RGBaumgartner, JWLot, and JEFesmirel, published June 30, 2009, in practice the intermediate space of a self-supporting spherical tank is depressurized to improve the insulating performance of the tank.

[0007] Nevertheless, the evacuation method for evacuating such intermediate spaces by means of a vacuum pump in the tank is a time consuming and energy intensive process.

[0008] In other words, it is difficult to exhaust all of the air that is initially present in the space, and therefore it is difficult to exhaust nitrogen and oxygen, which are the main components of air. Summary of the Invention

[0009] Certain aspects of the invention stem from the observation that when a tank is cooled, chemical species such as oxygen and nitrogen, which are initially in the gas phase, can condense to the liquid phase and, possibly in a second step, solidify to the solid phase if the pressure and temperature are sufficiently reduced. Thus, for example, nitrogen can easily diffuse into the primary space in the liquid phase and subsequently solidify.

[0010] This phenomenon can lead to damage to the tank, in particular causing a reduction in the insulating properties of the tank due to the formation of liquid or ice which spreads in the thickness direction of the primary space, thus forming thermal bridges.

[0011] One idea underlying the present invention is to propose a vacuum method for evacuating the intermediate space in a sealed, insulated tank.

[0012] Another idea underlying the present invention is to propose an improved evacuation method that offers advantages in terms of speed and energy consumption for evacuation of the intermediate space in a closed, insulated tank.

[0013] Another idea underlying the present invention is to propose a vacuum method for evacuating the intermediate space in a closed, insulated tank which is more economical in terms of energy and costs than known vacuum methods.

[0014] Another idea underlying the present invention is to propose a closed, insulated tank containing in its intermediate space a gas phase exhibiting excellent physicochemical properties.

[0015] In particular, the idea behind the invention is to propose a gas phase in an intermediate space under conditions which, in the event of a temperature reduction, allow said gas phase to condense from the gas phase into a solid phase without an intervening liquid phase.

[0016] According to one embodiment, the present invention provides a method for evacuating an intermediate space in a sealed, insulated tank, the tank comprising an outer sealing wall, an inner sealing wall located at a distance from the inside of the outer sealing wall and defining an interior space intended to contain a liquefied gas, preferably liquefied hydrogen, and an intermediate space located between the outer sealing wall and the inner sealing wall, the method comprising the steps of replacing a gas phase present in the intermediate space with a replacement gas phase at a first temperature, the first temperature being higher than 273 K, the replacement gas phase being composed of one or more main chemical species and possibly one or more residual chemical species, the step of replacing the gas phase comprising the steps of injecting the replacement gas phase into the intermediate space at a first pressure, the step of removing the gas phase in the intermediate space from the intermediate space ... the first pressure being less than 500 kPa in absolute value, the main species being in a gaseous state at the first temperature and at a partial pressure less than the first pressure, the main species exhibiting a saturation vapor pressure at any temperature less than 126 K that is less than the saturation vapor pressure of nitrogen at temperatures less than 126 K, the temperature in the inner space being greater than 273 K, followed by a step of reducing the pressure in the intermediate space to a pressure of an absolute value less than a pressure threshold, and a step of cooling the tank by injecting a fluid at a second temperature less than 273 K into the tank, the pressure threshold being less than the triple point of the main species so as to condense the main species into a solid phase upon cooling of the tank, and the residual species being at a partial pressure less than 0.1 kPa.

[0017] The initially present gas phase comprises, for example, air, which is mainly composed of nitrogen and oxygen. It is therefore important to replace this initially present gas phase in order to prepare the evacuation of the intermediate space. The main or each main chemical species is therefore in gaseous state before the cooling of the tank and, when the temperature is reduced, condenses into a solid phase in the form of snow or icicles, without passing through a liquid state. This condensation therefore significantly reduces the volume occupied by the main chemical species and therefore reduces the pressure prevailing in the intermediate space. Furthermore, the risk of the chemical species present in the intermediate space condensing into the liquid phase and spreading into the primary space is significantly reduced. The formation of thermal bridges across the intermediate space is also significantly reduced.

[0018] According to one embodiment, such a vacuum method may include at least one of the following features:

[0019] According to one embodiment, said first pressure has an absolute value of less than 110 kPa, thus exerting only moderate pressure on the sealing wall, allowing a relatively lightweight construction, particularly in the form of a membrane.

[0020] According to one embodiment, said pressure threshold is lower than 1 kPa, preferably lower than 0.1 kPa. Thus, the amount of material that can condense during cooling is relatively small.

[0021] According to one embodiment, the saturated vapor pressure of the main species at any said temperature below 126 K is less than 1 / 10, preferably less than 1 / 1000, more preferably less than 1 / 10000, than the saturated vapor pressure of nitrogen at said temperature below 126 K.

[0022] The residual species are at a partial pressure of less than 10 Pa, preferably less than 1 Pa.

[0023] Therefore, the amount of residual species present in the space that can condense into the liquid phase is very small. These features maintain the insulating capacity of the tank.

[0024] According to one embodiment, the predominant species is selected among carbon dioxide and trans-1,3,3,3-tetrafluoropropene.

[0025] According to one embodiment, the displacement gas phase comprises carbon dioxide as the single predominant species.

[0026] Thus, when the tank is cooled, the carbon dioxide condenses into the solid phase without going through a liquid phase, forming a more or less porous solid phase. Carbon dioxide is the preferred main species that can easily condense into the solid phase during the cooling of the tank. When the carbon dioxide undergoes a phase transition from gas to solid phase, the pressure in the intermediate space is further reduced. This improves the insulation of the tank.

[0027] According to one embodiment, the step of replacing the gas phase present in the intermediate space comprises a step of sucking the gas phase present in the intermediate space outside the outer sealing wall until the absolute air pressure in the intermediate space is lower than a second air pressure threshold, said second air pressure threshold being lower than 20 kPa, preferably lower than 10 kPa, and more preferably lower than 1 kPa, followed by a step of injecting the replacement gas phase into the intermediate space.

[0028] According to one embodiment, the steps of sucking the gas phase present in the intermediate space and injecting the replacement gas phase are performed repeatedly.

[0029] According to one embodiment, the step of replacing the gas phase present in the intermediate space includes simultaneously sucking the gas phase present in the intermediate space to the outside of the outer sealing wall and injecting the replacement gas phase into the intermediate space in order to scavenging the intermediate space with the replacement gas phase.

[0030] According to one embodiment, said first temperature is higher than 330 K, preferably higher than 373.15 K. Thus, water present in the intermediate space at ambient temperature evaporates and can easily be evacuated from said intermediate space.

[0031] According to another embodiment, cooling of the tank is achieved by spraying a fluid into the interior space of the tank.

[0032] According to one embodiment, cooling of the tank is performed by filling said interior space of the tank via a filling line exiting at the bottom of the tank.

[0033] According to one embodiment, the fluid is liquid hydrogen.

[0034] According to one embodiment, the fluid is liquid argon, liquid helium, or liquid dinitrogen.

[0035] According to one embodiment, the insulated sealed tank comprises a secondary sealing membrane located between the outer sealing wall and the inner sealing wall, the intermediate space being formed between the secondary sealing membrane and the inner sealing wall, the inner sealing wall being a primary sealing membrane, and the intermediate space comprising a support element extending in a thickness direction for supporting the primary sealing membrane.

[0036] Such support elements can be made in a variety of forms, for example in the form of blocks of insulation, rigid box sections, pillars, spacer walls, and the like.

[0037] According to one embodiment, the present invention also provides a sealed, insulated tank comprising an outer sealing wall, an inner sealing wall located at a distance from the inside of the outer sealing wall and defining an interior space intended to contain a liquefied gas, preferably liquefied hydrogen, and an intermediate space located between the outer sealing wall and the inner sealing wall, the intermediate space comprising a gas phase, the gas phase being composed of one or more main chemical species and possibly one or more residual chemical species, the main chemical species exhibiting, at any temperature below 126 K, a saturated vapor pressure lower than the saturated vapor pressure of nitrogen at said temperature below 126 K, the gas phase in the intermediate space being at a pressure lower in absolute value than a pressure threshold, the pressure threshold being lower than the triple point of the main chemical species and the residual chemical species being at a partial pressure lower than 0.1 kPa.

[0038] According to one embodiment, the interior space contains a liquefied gas, the liquefied gas having a temperature below 273K.

[0039] According to one embodiment, the interior space contains a liquefied gas, said liquefied gas having a temperature below 173K, preferably below 123K, such as below 50K.

[0040] According to one embodiment, the interior space contains liquid hydrogen.

[0041] According to one embodiment, the predominant species is selected among carbon dioxide and trans-1,3,3,3-tetrafluoropropene.

[0042] According to one embodiment, the carbon dioxide is the single predominant species in the gas phase.

[0043] According to one embodiment, the tank comprises a secondary sealing membrane located between the outer sealing wall and the inner sealing wall, the intermediate space being formed between the secondary sealing membrane and the inner sealing wall, the inner sealing wall being a primary sealing membrane, and the intermediate space comprising a primary insulating barrier supporting the primary sealing membrane.

[0044] Such tanks may form part of an onshore storage facility, for example for storing liquid hydrogen, or may be mounted on floating, coastal or deep-sea structures, in particular ships, floating storage and regasification units (FSRUs), floating production and storage offshore units (FPSOs) and the like.

[0045] According to one embodiment, a vessel used for transporting liquefied gas has a double hull and said tank is arranged within said double hull.

[0046] According to one embodiment, the double hull comprises an inner hull which forms the load-bearing structure of the tank.

[0047] According to one embodiment, the present invention also provides a transportation system for liquefied gas, comprising said vessel and an insulated pipe arranged to connect said tank installed in the hull of said vessel to an onshore or floating storage facility.

[0048] According to one embodiment the invention provides a method of loading or unloading on board a vessel, according to which liquefied gas is transferred through insulated pipes from an onshore or floating storage facility to said tanks of said vessel or from said tanks of said vessel to said onshore or floating storage facility.

[0049] The invention can be better understood in the following detailed description of some specific embodiments of the invention, given by way of non-limiting example with reference to the accompanying drawings, in which further objects, details, features and advantages are more clearly indicated. [Brief description of the drawings]

[0050] [Figure 1] FIG. 1 is a perspective cross-sectional view of a sealed, insulated tank having a membrane according to one embodiment. [Diagram 2] FIG. 2 is a partial schematic cross-sectional view of a portion of the tank in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the intermediate space of the tank in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a free-standing tank according to another embodiment. [Diagram 5] FIG. 5 is a schematic cross-sectional view of a ship's tank and a terminal for loading / unloading this tank. [Figure 6] FIG. 6 shows a log / log scale diagram showing the trends in saturation vapor pressure of several chemical species as a function of temperature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] With reference to FIG. 1 there is seen a sealed, insulated tank 1 intended to receive a liquefied gas, for example liquid hydrogen. The tank 1 rests on a load-bearing structure formed by the inner hull (not shown) of a ship with a double hull (not shown). The tank 1 has a generally polyhedral or prismatic shape. The tank 1 has a first transverse wall 2 and a second transverse wall 3, here octagonal. In FIG. 1 the first transverse wall 2 is partially displayed in order to visualize the interior space of the tank 1. The tank 1 comprises a ceiling wall 4, a bottom wall 5, a bottom chamfered wall 6, a side wall 7 and an upper chamfered wall 8. The ceiling wall 4, the bottom wall 5, the bottom chamfered wall 6, the side wall 7 and the upper chamfered wall 8 run in the longitudinal direction of the ship, linking the first transverse wall 2 and the second transverse wall 3 at a transverse edge 9 and meeting at a longitudinal edge 10.

[0052] With reference to FIG. 2, the sealed, insulated tank 1 comprises, from the outside to the inside of the tank 1, an outer sealing wall 11, a secondary insulating barrier 20 comprising a block of insulating foam and fixed to said outer sealing wall 11, a corrugated secondary sealing membrane 24 supported by said insulating barrier 20, a primary insulating barrier 25 comprising an intermediate space 30 with a gas phase and supporting pillars, and a primary sealing membrane 26 intended to be in contact with the liquefied gas contained in said tank 1 and supported by said primary insulating barrier 25.

[0053] The gas phase in the intermediate space 30 is composed of one or more main chemical species, for example carbon dioxide, and possibly one or more residual chemical species.

[0054] The predominant species exhibits a saturation vapor pressure at any temperature below 126 K that is less than the saturation vapor pressure of nitrogen at any temperature below 126 K. In other words, the species exhibits a saturation vapor pressure of N, as shown in the log / log scale diagram in FIG. 2 On a log / log scale, the saturation vapor pressure curves of the species are roughly similar, but offset with temperature. However, above 126 K, the N 2 The equilibrium curve stops and it is not possible to compare the difference with the saturated vapor pressure of other chemical species.

[0055] The pressure in the intermediate space 30 is a pressure whose absolute value is lower than the triple points of each of the main chemical species mentioned above.

[0056] The residual species are at a partial pressure of less than 0.1 kPa.

[0057] According to another embodiment, the tank 111 is a self-supporting tank and comprises, from the outside to the inside, a load-bearing structure 12, an outer sealing wall 110, an intermediate space 130 containing a gas phase and a thermal insulating barrier 125, an inner sealing wall 126 and an interior space 13 intended to contain a liquefied gas, for example liquid hydrogen. As an alternative to a self-supporting tank, the above-mentioned tank may also be of the type with an inverted membrane, i.e. with a rigid inner wall and a flexible membrane spaced apart from the rigid inner wall.

[0058] As shown in FIG. 4, the gas phase of the intermediate space 130 may be similar to the gas phase of the intermediate space 30 shown in FIGS.

[0059] With reference to FIG. 3, the method of evacuating the interior space in the sealed, insulated tank is described as follows.

[0060] Each element is the same as or similar to that shown in FIG. 2 and is given the same reference numeral.

[0061] The method for evacuating the intermediate space in the sealed insulated tank includes the following.

[0062] The gas phase present in the intermediate space is replaced with a replacement gas phase at a temperature above 273K.

[0063] The replacement of the replacement gas phase is performed via a gas management facility 110 connected to the tank 1 .

[0064] The gas management facility 110 comprises a supply line 40 linked to a gas source 41 and a compressor 50 and emerging into the intermediate space 30. The gas source 41 comprises a gas tank filled with said one main chemical species, for example carbon dioxide, or a gas generator capable of generating said one main chemical species. A suction line 42 is linked to a vacuum pump 43 and emerging into the intermediate space 30.

[0065] The gas management installation 110 may further comprise different elements making it possible to parameterise and monitor the suction and injection of gases. For example, the gas management installation 110 comprises one or more devices selected from the following devices: a gas analyzer 44 for analysing the gas extracted from the secondary space via the suction line 42, a gas input flow meter 46 and / or a gas output flow meter 45, a control unit 47, a pressure sensor 48 located in said intermediate space 30, and a temperature sensor 49 located in said intermediate space 30.

[0066] Thus, while the vacuum pump 43 is active, the gas phase is sucked out of the intermediate space 30 via the suction line 42 and replaced by injecting the main chemical species in gas phase from the gas source 41 into the intermediate space 30.

[0067] Optionally, this replacement procedure can be repeated until the gas phase exhibits the desired parameters.

[0068] In a first example, the gas source is CO 2 In a second example, the gas source is a source of trans-1,3,3,3-tetrafluoropropene.

[0069] The vacuum pump 43 is activated to reduce the pressure to an absolute pressure below the triple point of the main species.

[0070] In the first example, the triple point of carbon dioxide is set to 519 kPa at 217 K. Thus, for carbon dioxide, the pressure is reduced to an absolute pressure less than 519 kPa.

[0071] In the second example, the triple point of trans-1,3,3,3-tetrafluoropropene is set to 0.22 kPa at 168 K. Thus, for trans-1,3,3,3-tetrafluoropropene, the pressure is reduced to an absolute pressure less than 0.22 kPa.

[0072] The internal space 51 of the tank 1 is then filled with a liquefied gas, for example liquid hydrogen. The temperature in the intermediate space is therefore reduced by heat conduction. The temperature of the main species in the gas phase is reduced and they condense directly into the solid phase without passing through the liquid state. This phenomenon makes it possible to further reduce the pressure in the intermediate space.

[0073] The method described above can be equally applied to the free-standing tank 111 shown in FIG. 4, and to other tanks having an intermediate space and intended to contain liquefied gas.

[0074] Dinitrogen (N 2 ), carbon dioxide (CO 2 A table comparing each of the major species, including fluoropropene (R1234ze(E)), and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)), is shown below: [Table 1]

[0075] The second column corresponds to the temperature in Kelvin (K) of the triple point of the main chemical species specified in the left hand column.

[0076] The third column corresponds to the pressure in kilopascals (kPa) of the triple point of the main species specified in the left hand column.

[0077] The fourth and fifth columns correspond to the saturation pressure (Psat) at 126K and 303K, respectively, for the major species identified in the first column on the left.

[0078] The sixth column corresponds to the ratio of the saturation pressure of dinitrogen to the saturation pressure at 126 K of the major species specified in the left hand column.

[0079] Therefore, the saturation vapor pressure of the main species at any temperature below 126 K is CO 2 The ratio is 242857 for R1234ze(E) and 15455 for R1234ze(E), both of which are lower than the saturated vapor pressure of dinitrogen at any temperature lower than 126 K.

[0080] 5, a cross-sectional view of a ship 70, for example a hydrogen tanker intended to transport liquefied hydrogen, shows a sealed, insulated tank 71, generally formed in a prismatic shape, mounted inside the vessel's double hull 72. The wall of the tank 71 comprises a primary sealed, insulated barrier intended to be in contact with the liquefied gas contained in the tank, preferably liquefied hydrogen, a secondary sealed barrier arranged between the primary sealed, insulated barrier and the vessel's double hull 72, and two insulating barriers arranged respectively between the primary and secondary sealed barriers and between the secondary sealed barrier and the double hull 72.

[0081] As is known per se, a loading / unloading pipeline 73 installed on the top deck of the vessel is capable of transferring a cargo of liquefied gas from or to the tanks 71 by means of suitable connectors to an offshore or port terminal.

[0082] FIG. 5 shows an example of a marine terminal including a loading / unloading station 75, an undersea line 76, and an onshore facility 77. The loading / unloading station 75 is a fixed offshore facility with a movable arm 74 and a riser 78 supporting the movable arm 74. The movable arm 74 supports a bundle of insulated flexible pipes 79 that can be connected to a loading / unloading pipeline 73. The orientable movable arm 74 fits any vessel template. A link line, not shown, runs inside the riser 78. The loading / unloading station 75 allows loading / unloading the vessel 70 from the onshore facility 77 or unloading the vessel 70 from the onshore facility 77. The onshore facility 77 includes a liquefied gas storage tank 80 and a link line 81 linked to the loading / unloading station 75 by an undersea line 76. The subsea line 76 allows the liquefied gas to be transported between the loading / unloading station 75 and the onshore facility 77 over long distances, for example more than 5 km, thereby enabling the vessel 70 to remain a sufficient distance from shore during loading and unloading operations.

[0083] To generate the pressure required to transport the liquefied gas, pumps on board the vessel 70 and / or pumps installed at the loading / unloading station 75 and / or pumps installed at the onshore facility 77 can be used, or the pressure increase in the internal space of the tank caused by evaporation of the liquefied gas stored in the tank can be allowed to occur.

[0084] Although the present invention has been described with reference to some specific embodiments, it is clear that the invention is in no way limited thereto, and that all technical equivalents of the described means and combinations thereof, provided that the conditions are met, are encompassed within the scope of the present invention.

[0085] Use of the terms "comprise" or "include" and their conjugations does not exclude the presence of other elements or steps in addition to those stated in a claim.

[0086] In the claims, any reference signs placed between parentheses shall not be construed as construing as limiting the claim.

Claims

1. A vacuuming method for vacuuming an intermediate space inside a sealed insulated tank (1,111), wherein the sealed insulated tank (1,111) comprises an outer sealed wall (11,110), an inner sealed wall (26,126) located at a distance from the inside of the outer sealed wall (11,110) and partitioning an internal space (13) intended for containing liquefied gas, and an intermediate space (30,130) located between the outer sealed wall (11,110) and the inner sealed wall (26,126). The aforementioned vacuuming method is, A step of replacing the gas phase present in the intermediate space (30, 130) with a replacement gas phase at a first temperature, wherein the first temperature is higher than 273 K, the replacement gas phase is composed of one or more main chemical species and one or more possible residual chemical species, the step of replacing the gas phase includes injecting the replacement gas phase into the intermediate space (30, 130) at a first pressure, the first pressure in the intermediate space is less than 500 kPa in absolute value, the main chemical species are in a gaseous state at a partial pressure lower than the first temperature and the first pressure, the main chemical species exhibit a saturated vapor pressure lower than the saturated vapor pressure of nitrogen at any temperature below 126 K, and the temperature in the internal space (13) is higher than 273 K. Next, the pressure in the intermediate space (30, 130) is reduced to a pressure with an absolute value lower than the pressure threshold. The steps include: cooling the sealed insulated tank (1,111) by injecting a fluid at a second temperature lower than 273K into the internal space (13) of the sealed insulated tank (1,111); Equipped with, The pressure threshold is set lower than the triple point of the main chemical species so that the main chemical species condenses into a solid phase when the sealed insulated tank (1,111) is cooled. The residual chemical species have a partial pressure lower than 0.1 kPa. Vacuuming method.

2. The vacuuming method according to claim 1, wherein the first pressure is less than 110 kPa in absolute value.

3. The vacuuming method according to claim 1 or claim 2, wherein the pressure threshold is lower than 1 kPa, preferably lower than 0.1 kPa.

4. The vacuuming method according to claim 1 or claim 2, wherein the saturated vapor pressure of the main chemical species at any temperature below 126 K is lower than the saturated vapor pressure of nitrogen at a temperature below 126 K by a ratio of less than 1 / 10, preferably less than 1 / 1000, and more preferably less than 1 / 10000.

5. The vacuuming method according to claim 1 or claim 2, wherein the residual chemical species are at a partial pressure of less than 10 Pa, preferably less than 1 Pa.

6. The vacuuming method according to claim 1 or claim 2, wherein the main chemical species is selected from carbon dioxide and trans-1,3,3,3-tetrafluoropropene.

7. The vacuuming method according to claim 6, wherein the substituted gas phase contains carbon dioxide as a single main chemical species.

8. The step of replacing the gas phase present in the intermediate space (30, 130) is: A step of drawing the gas phase present in the intermediate space (30, 130) to the outside of the outer sealing wall (11, 110) until the absolute pressure in the intermediate space (30, 130) falls below a second atmospheric pressure threshold, wherein the second atmospheric pressure threshold is lower than 20 kPa, preferably lower than 10 kPa, and more preferably lower than 1 kPa. Next, the step of injecting the displacement gas phase into the intermediate space (30, 130) A vacuuming method according to claim 1 or claim 2, including the method described in claim 1 or 2.

9. The vacuuming method according to claim 8, wherein the steps of aspirating the gas phase present in the intermediate space (30, 130) and injecting the replacement gas phase are repeated.

10. The vacuuming method according to claim 1 or claim 2, wherein the step of replacing the gas phase present in the intermediate space (30, 130) includes simultaneously sucking the gas phase present in the intermediate space (30, 130) to the outside of the outer sealed wall (11, 110) and injecting the replacement gas phase into the intermediate space (30, 130) in order to ventilate the intermediate space (30, 130) using the replacement gas phase.

11. The vacuuming method according to claim 1 or claim 2, wherein the first temperature is higher than 330K, preferably higher than 373.15K.

12. The vacuuming method according to claim 1 or claim 2, wherein the step of cooling the sealed insulated tank (1,111) is performed by spraying a fluid into the sealed insulated tank (1,111).

13. The vacuuming method according to claim 1 or claim 2, wherein the step of cooling the sealed insulated tank (1,111) is performed by filling the internal space (13) of the sealed insulated tank (1,111) through a filling line appearing at the bottom of the sealed insulated tank (1,111).

14. The vacuuming method according to claim 1 or claim 2, wherein the fluid is liquid hydrogen.

15. The sealed insulated tank (1) includes a secondary sealing membrane located between the outer sealing wall and the inner sealing wall. The intermediate space is formed between the secondary sealing membrane and the inner sealing wall, The aforementioned inner sealing wall is a primary sealing membrane. The vacuuming method according to claim 1 or 2, wherein the intermediate space comprises a primary insulating barrier supporting the primary sealing membrane.

16. The outer sealed wall, An inner sealed wall (26, 126) is located at a distance from the inside of the outer sealed wall (11, 110) and partitions an internal space (13) intended to contain liquefied gas, An intermediate space (30, 130) located between the outer sealing wall (11, 110) and the inner sealing wall (26, 126), Equipped with, The aforementioned intermediate space (30, 130) includes a gas phase. The gas phase is composed of one or more main chemical species and one or more possible residual chemical species. The main chemical species exhibits a saturated vapor pressure lower than the saturated vapor pressure of nitrogen at any temperature below 126 K. The gas phase in the intermediate space (30, 130) has a pressure with an absolute value lower than the pressure threshold. The pressure threshold is lower than the triple point of the main chemical species. The residual chemical species have a partial pressure lower than 0.1 kPa. A sealed, insulated tank.

17. The internal space (13) contains liquefied gas, The sealed insulated tank according to claim 16, wherein the liquefied gas has a temperature lower than 273 K.

18. The sealed, insulated tank according to claim 17, wherein the internal space (13) contains liquid hydrogen.

19. The sealed, insulated tank according to any one of claims 16 to 18, wherein the main chemical species is selected from carbon dioxide and trans-1,3,3,3-tetrafluoropropene.

20. The sealed insulated tank according to any one of claims 16 to 18, wherein the carbon dioxide is the single main chemical species of the gas phase.

21. The sealed insulated tank (1) includes a secondary sealing membrane (24) located between the outer sealing wall (11) and the inner sealing wall (26). The intermediate space (30) is formed between the secondary sealing membrane (24) and the inner sealing wall (26), The inner sealing wall (26) is a primary sealing membrane. The sealed insulated tank according to any one of claims 16 to 18, wherein the intermediate space (30) comprises a primary insulated barrier (25) supporting the primary sealing membrane (26).

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