Insulated modular unit for leak-tight insulated tanks

Abstract

The present invention relates to an insulating modular unit (3,7) for the insulation of leaktight tanks for the storage of liquids, characterized in that the insulating modular unit (3,7) comprises an insulating filling, the insulating filling comprising a powdered insulating material containing a main component selected from fumed silica, silica aerogel and mixtures thereof, and at least one anion exchange compound in the form of a powder mixed with the powdered insulating material, the insulating filling being not enclosed in a gas-impermeable envelope.

Description

[Technical Field]

[0001] The present invention relates to the field of leak-tight insulated tanks. In particular, the invention relates to the field of leak-tight insulated tanks comprising a metallic leak-tight membrane and an insulating modular unit. The invention further relates to an insulating modular unit for insulating leak-tight tanks for the storage and / or transportation of liquids. [Background technology]

[0002] WO 2019 / 122757 discloses an insulating barrier for a storage tank for cold liquids, comprising a plurality of juxtaposed insulating boxes. The boxes include compartments and powdered insulating fillers disposed within the compartments. The powdered fillers offer an excellent compromise between low density and sufficient insulating performance, and are not or only slightly susceptible to irreversible settling after immersion in the liquid stored in the tank. The powdered fillers are typically selected from fumed silica, silica aerogel, and mixtures thereof.

[0003] These powdered fills always contain small amounts of chlorine, i.e., above about 10 parts per million (ppm), due to their manufacturing process. Solid-state diffusion of the insulation in the form of dust, which occurs when suspended in air and displaces with the air movement, or when displaced by gravity or any accelerations experienced by the tanker, can cause contact between the chlorine and the metallic leaktight membrane, such as stainless steel or alloys with a low thermal expansion coefficient, especially iron-nickel alloys such as Invar®, which can cause pitting of the leaktight membrane. Moisture can also transport the chlorine present in the powdered fill, and condensation can bring the chlorine into contact with the leaktight membrane, causing pitting of the metal.

[0004] Although these powdered fillers are available without elemental chlorine, they are very expensive.

[0005] Therefore, in general, insulating barriers with a gas-permeable envelope and a powdered filling containing a material selected from fumed silica, silica aerogel, and mixtures thereof, and small amounts of chlorine, tend to exhibit corrosion phenomena of the external metal structure, which therefore weaken the leak-tight membrane and are particularly detrimental to leak-tight insulated tanks for the storage and / or transport of liquids, depending on the technology used.

[0006] Therefore, there is a need to develop a tank that solves this corrosion problem without compromising the insulating performance of the insulating barrier, incorporating a gas-permeable insulating barrier containing insulating fillers based on fumed silica, silica aerogel, and mixtures thereof that will not corrode the external metal structures that are sensitive to low concentrations of chlorine.

[0007] More specifically, there is a need to improve the thermal barrier of liquid storage tanks in order to overcome the corrosion drawbacks observed in metallic leak-tight membranes that are sensitive to low concentrations of chlorine, such as, for example, iron and nickel, more particularly the alloy of iron (64%) and nickel (36%) known as Invar®, as disclosed, for example, in patent application FR 3 075 918.

[0008] Furthermore, the following documents are also known in the field of thermal insulation or protection containing fumed silica:

[0009] WO 2014 / 184393 describes a method for producing a silica aerogel containing 40% to 93% fumed silica or silica aerogel and a specific surface area of ​​100 m2 as determined by BET. 2 The present invention describes a composition comprising 5% to 50% particles having a specific surface area of ​​100 m2 or less, as determined by BET. These particles are selected from a large product list and are chosen according to their role in trapping gas molecules to slow the increase in internal pressure and maintain optimal thermal insulation performance. The size of the fumed silica particles is 5 nm to 50 nm. The size of the silica aerogel particles is 2 nm to 50 nm or 50 nm to 2000 nm, depending on the manufacturing process. The specific surface area of ​​100 m2, as determined by BET, is 100 m2 or less. 2Particles that are less than 50m / g may also be 2 / g or less, or alternatively, 30 m 2 / g or less. This composition is used in the manufacture of Vacuum Insulation Panels (VIPs) used in the construction of new buildings and in the insulation of existing buildings, and as insulation in refrigeration equipment, pipes and / or industrial machinery.

[0010] Korean Patent Publication No. 20130067712 discloses a flame-retardant heat insulating material containing 35% to 99.5% by weight of fumed silica having a microporous structure, 0.3% to 25% by weight of a reinforcing material, and 0.2% to 55% by weight of a heat-resistant filler. The reinforcing material is selected from glass fiber, ceramic fiber, carbon fiber, quartz fiber, and mixtures thereof. The heat-resistant filler may be silicon carbide, zirconium silicate, graphite, metakaolin, titanium dioxide, pyrophyllite, vermiculite, perlite, calcium silicate, etc.

[0011] JP 2013-104491 A relates to the field of processes for manufacturing vacuum insulation materials. For applications in buildings, freezers, and refrigerators, in particular, powder is sealed in a gas-impermeable package under reduced pressure. This powder is called fumed silica, and its primary particles have an average size of 5 to 100 nm and a water content of less than 1% by weight. Furthermore, this powder may contain gas and moisture adsorbents such as synthetic zeolite, activated carbon, activated alumina, silica gel, dawsonite, and hydrotalcite, as well as chemical adsorbent particles such as oxides and hydroxides of alkali metals and alkaline earth metals. Summary of the Invention

[0012] The present invention therefore generally aims to suppress, and even eliminate, the phenomenon of corrosion of metallic leak-tight membranes in leak-tight tanks incorporating a plurality of insulating modular units containing insulating fillers based primarily on fumed silica, silica aerogel, and mixtures thereof.

[0013] More specifically, the present invention aims to suppress or even eliminate the phenomenon of corrosion of the leak-tight membrane of a leak-tight insulated tank comprising a plurality of gas-permeable modular units and configured to store a liquid selected from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon, and liquid hydrogen.

[0014] A first aspect of the present invention relates to an insulated modular unit for insulating a leak-tight tank for storing liquids, the modular unit comprising an insulating filler, the insulating filler comprising a powdered insulating material having a main component selected from fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound capable of capturing chloride anions in exchange for the release of at least one other anion, the anion exchange compound being in the form of a powder mixed with the powdered insulating material, and the insulating filler not being enclosed in a gas-impermeable envelope.

[0015] The insulating filler may further include fibers, such as, for example, glass or carbon fibers. The insulating filler may also include a material that makes it opaque to infrared radiation, such as SiC, TiO2, graphite, or carbon black. The insulating filler may also include a filler, such as perlite, to limit settling of the insulating filler, especially in the event of accidental immersion by liquefied gas.

[0016] The following definitions will enable a better understanding of the scope of the disclosure.

[0017] The term "modular unit" means a self-supporting solid object, such as a box or rigid panel, which can be arranged as needed and in any number desired. The shape may vary, such as cylindrical, parallelepiped, etc.

[0018] The term "powdered insulation" refers to any composition in powder form that prevents heat loss. Such powders may be packaged as a mass, lightly compressed into a rigid container or flexible envelope, or compressed and densified into units or panels that are sufficiently self-supporting to be handled. Such powders may also be packaged within a flexible envelope that is inserted into a rigid container to form a handleable, self-supporting panel. For example, such powders may be packaged in a range of 80 kg / m², depending on the intended application and desired mechanical properties. 3 to 500 kg / m 3 The packaging may be at a density between 0.1 and 1.0.

[0019] The term "anion exchange compound capable of capturing chloride anions" refers to OH - or CO3 2- The term "chloride exchanger" is understood to mean any compound in powder form containing a chlorine group and capable of exchanging the anions contained in its structure for other chloride anions present in the insulating packing. Examples include clays, layered double hydroxide (LDH) compounds, synthetic hydrotalcites, crosslinked ion-exchange polymers, and mixtures thereof. LDH compounds are solid compounds formed from stacks of layers containing metal cations, between which anions and water molecules can be inserted. Their structure is based on that of brucite, Mg(OH)2, in which some of the divalent ions are randomly replaced by trivalent ions, resulting in an excess positive charge on the octahedral faces. To ensure overall electrical neutrality, this excess charge is compensated for by the negative charge of the anions inserted in the interlayer spaces. As used herein, LDH can include hydrated and dehydrated forms. Anion-exchange compounds can also capture other ionic halogens, such as fluorine, whose physical properties are similar to those of chlorine.

[0020] The term "leak-tight membrane" is understood to mean a thin film or layer of material made of metal or metal alloy, making it possible to make the tank leak-tight with respect to the liquid, for example Invar®.

[0021] The term "average apparent size" is understood to mean that the particles have a particle size distribution whose mean value is so defined.

[0022] The term "proportion by weight" is understood to mean the percentage by weight (%w) indicating the proportion by weight of a component in the total mixture.

[0023] The term "volume fraction" is understood to mean the volume of a component divided by the sum of the volumes of all components of the mixture.

[0024] The term "gas-permeable envelope" is understood to mean a rigid, semi-rigid or flexible material that defines a closed space. Examples of these gas-permeable materials are, for example, wood, vibration-damping materials, textile materials, and composite materials such as glass fiber sheets, polymer fiber sheets, plywood, compressed cardboard, etc. Non-limiting examples of envelopes comprising rigid reinforcement can be found in particular in patent applications FR 2 867 831, WO 2013 / 017773 and WO 2014 / 020257.

[0025] In one embodiment, the insulated modular unit includes a gas-permeable envelope defining at least one compartment, with the insulating filler disposed within the compartment.

[0026] In one embodiment, the powdered insulation contains little or no binder, such as an adhesive polymer.

[0027] In one embodiment, the proportion of binder used to prepare the insulating filler is less than 12% by weight of the insulating filler, for example, 0.3 to 12%, as a higher amount will reduce the insulating performance of the modular unit.

[0028] In one embodiment, the anion exchange compound is hydrated and comprises water molecules.

[0029] In one embodiment, the anion exchange compound is selected from the group consisting of clay, layered double hydroxide (LDH) compounds, synthetic hydrotalcite (MgAl(OH) 16 Magnesium aluminum hydroxycarbonate with the formula CO3·4H2O), exchangeable anion OH - and CO3 2- Crosslinked anion exchange polymers, including for example Ion Exchanger III (Merck® product code 104767), and mixtures thereof.

[0030] In one embodiment, the anion exchange compound is a hydroxide ion (OH - ) and carbonate ions (CO3 2- )

[0031] In one embodiment, the LDH compound is II 1-x M III x (OH)2] x+ [A m- x / m nH2O] x- It is expressed by the formula M II and M III are the divalent and trivalent cations of the layer, respectively, and A represents the material of the intermediate layer, which is an anion.

[0032] A can be any anion that can be exchanged for the chloride anions present in the insulating packing. Preferably, A is not a halogen anion or a sulfide anion.

[0033] In one embodiment, the anion A of the LDH compound is a hydroxide ion (OH - ) and carbonate ions (CO3 2- ) is selected from.

[0034] By way of example, various types of LDH minerals suitable for the present invention can be listed below. Formula Mg6Al2(OH) 16 Hydrotalcite of CO3·4H2O (rhombohedral structure) Formula Mg6Al2(OH) 16 Manasite CO3·4H2O (hexagonal structure) Formula Mg6Al2(OH) 18 ·4H2O Makesnelite Formula Mg6Fe2(OH) 16 Pyroaurite of CO3·4H2O (rhombohedral structure) Formula Mg6Fe2(OH) 16 Sjögrenite, CO3·4H2O (hexagonal structure) Formula Mg 10 Fe2(OH) 24 CO3·2H2O collingite Formula Mg6Cr2(OH) 16 Stichtite with CO3·4H2O (rhombohedral structure) Formula Mg6Cr2(OH) 16 Baerbertite of CO3·4H2O (hexagonal structure) FormulaNi6Cr2(OH) 16 Takovite in CO3·4H2O Formula: Ni6Fe2(OH) 16 CO3·4H2O leavensite Formula Mg6Mn2(OH) 16 CO3·4H2O desalination

[0035] In one embodiment, the anion exchange compound is selected from synthetic hydrotalcites (see Example 1), cross-linked polymers (see Example 2), and mixtures thereof.

[0036] According to one embodiment, the anion exchange compound is in the form of particles having an average apparent size of between 1 μm and 50 μm, preferably between 1 μm and 25 μm, and more advantageously between 1 and 10 μm.

[0037] According to one embodiment, the mass proportion of anion exchange compound is between 1% and 30% by weight relative to said adiabatic packing, preferably between 5% and 20% by weight relative to said adiabatic packing.

[0038] According to one embodiment, the volume fraction occupied by the anion exchange compound in the insulating packing is less than 5%, preferably less than 1%.

[0039] According to one embodiment, the envelope comprises a rigid reinforcement including a bottom panel, a cover panel, and spacing elements that hold the bottom panel and the cover panel parallel and spaced apart from each other to absorb pressure, and the spacing elements of the modular units can be configured in various forms.

[0040] In one embodiment, the spacing elements of the modular unit include side walls arranged at the edges of the bottom panel and the cover panel, internal partitions extending between two opposing edges of the bottom panel and between two opposing edges of the cover panel, and / or support columns, in particular support columns of small cross-section distributed on the inner surfaces of the bottom panel and the cover panel.

[0041] A second aspect of the present invention is a leak-tight insulated tank comprising at least one insulating barrier and a metal leak-tight membrane in contact with the insulating barrier, the insulating barrier comprising a plurality of the modular units described above.

[0042] In one embodiment of the second aspect of the present invention, the leak-tight membrane has a low coefficient of thermal expansion, i.e., a linear thermal expansion coefficient (in length) from 20°C to 90°C of 2.0 x 10 -6 K -1 It is made of a nickel-steel alloy, where K stands for Kelvin: Preferably, the leak-tight membrane is Invar®, more precisely an alloy of iron (64%) and nickel (36%).

[0043] In one particular embodiment, the insulating barrier is a secondary insulating barrier, the leak-tight membrane is a secondary leak-tight membrane, and the tank further includes a primary insulating barrier in contact with the secondary leak-tight membrane, and a primary leak-tight membrane in contact with the primary insulating barrier and configured to contact the fluid contained in the tank.

[0044] In another particular embodiment, the insulating barrier is a primary insulating barrier, the leak-tight membrane is a primary leak-tight membrane configured to contact a fluid contained in the tank, and the tank further includes a secondary leak-tight membrane in contact with the primary insulating barrier, and a secondary insulating barrier in contact with the secondary leak-tight membrane.

[0045] In one embodiment, the storage tank is configured to store a liquid selected from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon, and liquid hydrogen.

[0046] Such tanks may form part of an onshore storage facility for storing, for example, LNG, or may be installed on floating structures onshore or at sea, in particular LNG carriers, Floating Storage and Regasification Units (FSRUs), Floating Production Storage and Offloading (FPSOs), etc. In the case of floating structures, the tanks may be intended for the transport of liquefied gas or may be configured to receive liquefied gas to be used, for example, as fuel for propulsion of the floating structure on any type of ship.

[0047] According to one embodiment, a vessel for the transportation of liquids comprises a double hull and a tank as described above installed in said double hull.

[0048] According to one embodiment, the invention also provides a method for loading or unloading such a vessel, characterized in that the liquid is transported from a floating or onshore storage facility to the tanks of the vessel or from the tanks of the vessel to the floating or onshore storage facility via insulated pipes.

[0049] According to one embodiment, the present invention also provides a liquid transfer system comprising a vessel as described above, an insulated pipe arranged to connect a tank installed in the hull of the vessel to a floating or land-based storage facility, and a pump for driving a flow of liquid through the insulated pipe from the floating or land-based storage facility to the tank of the vessel or from the tank of the vessel to the floating or land-based storage facility.

[0050] The present invention will be better understood with reference to the accompanying drawings, and other objects, details, features and advantages of the present invention will become more clearly apparent in the following description of some particular embodiments of the present invention, given by way of illustration only and not of limitation. [Brief explanation of the drawings]

[0051] [Figure 1] FIG. 1 is a partial cross-sectional view of a leak-tight tank wall comprising an insulated modular unit with a rigid wooden envelope. [Figure 2] FIG. 2 is a schematic perspective view of an insulating modular unit that can be included in the tank wall of FIG. 1 and includes a pillar. [Figure 3] FIG. 1 is a perspective view of a modular formwork element with a number of anchoring studs and a support structure incorporating insulating modular units. [Figure 4] Similar perspective view as in Figure 3, but with the modular formwork elements removed and junction insulators added. [Figure 5] FIG. 1 is a cross-sectional view of a complete assembly including samples corresponding to the corrosion reduction testing of Invar® described in Example 4. [Figure 6] 1 is a cross-sectional schematic view of a tank of an LNG carrier and a terminal for loading / unloading this tank. DETAILED DESCRIPTION OF THE INVENTION

[0052] With reference to Figure 1, there is seen a section of a double hull of a ship, designated by the number 1. The wall of the ship is constituted successively in the thickness direction of the wall by a secondary insulating barrier 2 formed of modular units 3 juxtaposed on the double hull 1 and held by secondary retaining elements 4, then a secondary leaktight membrane 5 carried by the modular units 3, then a primary insulating barrier 6 formed by modular units 7 juxtaposed and held on top of the secondary leaktight membrane 5 by primary retaining elements 8 themselves fixed to the secondary retaining elements 4, and finally a primary leaktight membrane 9 carried by the modular units 7. Further details regarding the construction of the modular units 3 and 7 can be found in French patent application FR 2 867 831.

[0053] The insulating filler (not shown), packaged in a flexible bag or in the form of a compressed unit, fills the interior space of the modular unit 3 and is composed of a powdered insulating material mixture, the powdered insulating material mixture including a main component selected from fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound, the anion exchange compound being an LDH compound and / or an exchangeable anion OH. - or CO3 2- The anion exchange crosslinked polymer comprises an anion exchange crosslinked polymer comprising, for example, Crosslinked Ion Exchange Polymer III (Merck® product code 104767).

[0054] Referring to FIG. 2 , according to another embodiment, the modular unit 53 comprises a bottom panel 54 to which a distribution support plate 55 is fixed. Rows of columns 56 and 60 are respectively placed and fixed on the corresponding distribution support plates 55. In particular, columns 57 of each row of columns 56 or 60 extend along the thickness of the modular unit 53 and thus along a direction perpendicular to the supporting wall 1. The columns 57 have a solid rectangular cross section. Each row of columns 56 or 60 is parallel to the side surfaces 58 of the modular unit 53. The column row supports a reinforced cover panel 59. The columns 57, in particular, allow stress acting on the cover panel 59 to be transmitted to the wall 1 and have a compression resistance function. Further details regarding the structure of the modular unit 53 can be found in WO 2014 / 020257.

[0055] The insulating filler (not shown), packaged in a flexible bag or in the form of a compressed unit, fills the space between the pillars 57 and is comprised of a powdered insulating material mixture, the powdered insulating material mixture including a primary component selected from fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound.

[0056] Referring to FIG. 3 , the integration of insulated modular units into a leak-tight insulated tank wall is described according to one embodiment. Such a leak-tight wall allows the production of containment vessels or tanks for storing and / or transporting cryogenic fluids, e.g., liquefied gases such as methane. Fixing studs 11, also called couplers, are regularly arranged and fixed to an external support structure 12. This support structure 12 can be any type of rigid partition with suitable mechanical properties, in particular a self-supporting metal sheet or, more generally, a concrete wall in land-based structures. Modular formwork elements 13 are arranged between the fixing studs 11 relative to the support structure 12. The modular formwork elements 13 thus have a shape that protrudes inward relative to the plane of the support structure 12. Together with the fixing studs 11 and the support structure 12, the modular formwork elements 13 form multiple compartments. The compartments include open sides on opposite sides of the support structure 12. The modular formwork elements 13 are longitudinal beams arranged at right angles to each other to form compartments with a rectangular shape. The modular formwork elements 13 may be provided with releasable fastenings that allow them to be fixed to the support structure 12 and / or to the fixing studs 11. The compartments are then filled with compressed panels of insulating fill 15 from their open sides to form a plurality of insulating sectors of compressed insulating fill 15. The compartments thus define templates for the production of the insulating sectors 15.

[0057] In one embodiment, short fibers, such as glass fibers, are mixed with the powdered insulation material prior to forming the compressed panel, which in addition to the powdered insulation material, comprises an insulating filler comprising fibers.

[0058] The insulating filler, not shown, fills the compartment and is comprised of a powdered insulating material mixture, the powdered insulating material mixture including a primary component selected from fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound.

[0059] When the modular formwork elements 13 are removed, the insulating sectors of compressed insulating fill 15 are separated by gaps created by the removal of the formwork elements.

[0060] To ensure thermal continuity, the gaps between the insulating sectors of the compressed insulating filler 15 are lined with bonded insulating elements 18, as shown in FIG. 4 . The bonded insulating elements 18 are placed between the insulating sectors of the compressed insulating filler 15 at room temperature under compressive stress. Therefore, when the insulating sectors of the compressed insulating filler 15 shrink under the influence of low temperatures, the bonded insulating elements 18 can relax and fill the gaps between the insulating sectors. According to one embodiment, the bonded insulating elements 18 are strips made of a flexible material, such as glass wool, polyester wadding, polyurethane (PU) foam, melamine foam, polyethylene (PE) foam, polypropylene (PP) foam, or silicone foam. The width of these strips is determined so that they are subjected to compressive stress between the insulating sectors of the compressed insulating filler 15 at room temperature.

[0061] The compositions and processes for preparing insulating fillers for forming insulating modular units are described below.

[0062] The insulating packing is made from a powdered insulating material including hydrophobic fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound.

[0063] Hydrophobic fumed silica is available, for example, under the tradename Aerosil R974 or Aerosil R812S, manufactured by Evonik.

[0064] Silica aerogel is available, for example, under the trade name P100 manufactured by Cabot Corporation and is ground to a particle size of less than 100 μm.

[0065] Additionally, the insulating filler may contain particulate fillers such as small expanded perlite available under the trade name CR615 manufactured by KD One Co., or glass microspheres available under the trade name Glass Bubble K1 manufactured by 3M, or liquid nitrogen compatible granular silica aerogel known under the trade name P400 manufactured by Cabot Corporation.

[0066] Example 1: Preparation of hydrotalcite-type anion exchange compound The anion exchange compound is obtained from Sigma Aldrich®. It is a synthetic hydrotalcite white powder with product code 652288 and a molecular weight of 603.98 g / mol. Its density is 2.06 and its particle size is 1-5 μm.

[0067] Example 2: Preparation of polymeric anion exchange compounds The anion exchange compound was an ion exchange resin available from Sigma Aldrich® under product code 104767, Analytical Ion Exchanger (Echangeur d'ions) III (Strongly Basic Anion Exchanger, OH - This is called the "type" (density 650-700 kg / m 3 It is a powder of cross-linked polymer. Its particle size is 496 to 674 μm.

[0068] The polymer was placed in a 70ZPS type impact mill operating at 16,000 revolutions per minute, with the selector set to 8,000 revolutions per minute and the air circulation speed at 80 m / s. 3 Set it to / h.

[0069] The following table shows the results of the particle size of the powder before and after milling, as measured by a Malvern brand "Mastersizer 3000" instrument.

[0070] [Table 1]

[0071] "DXX(v)=A" means that XX% of the volume fraction of the distribution of particles has a diameter less than A μm.

[0072] A powder containing particle sizes between 1 and 50 μm is obtained, with only 10% of the particles containing diameters larger than 19.6 μm.

[0073] Example 3: Preparation of anticorrosive pyrogenic packing using chloride anion exchanger There are two types of hydrophobic fumed silica used: Silica with a particle size of less than 200 μm available as Aerosil® R974 from Evonik Resource Efficiency GmbH Silica with a particle size of less than 200 μm, available as HDK® H30 from Wacker Chemie AG

[0074] The hydrophobic fumed silica is mixed with hydrotalcite or ground ion exchange resin as shown in Table 2.

[0075] Example 4: Corrosion inhibition test of Invar® by fumed silica with the addition of an anion exchanger Invar® alloy is obtained from Aperam Imphy in the form of hot rolled strip with a thickness of 0.7 mm.

[0076] Test pieces 65 mm long and 31.5 mm wide are taken from the strip. The test pieces are free of surface defects. To clean them, they are immersed in 95% ethanol for 15 minutes under ultrasonic irradiation. The blades are then dried under filtered, dry compressed air.

[0077] Various experiments are carried out, as shown in Table 2 below.

[0078] [Table 2]

[0079] The following accelerated aging protocol was applied: The accelerated aging conditions consisted of a temperature of 55°C and room humidity of 95% RH. As shown in Figure 5, the sample holder included a bottle 63, a perforated stopper 64 with a stopper lip 65, a filter 66, an Invar® test strip 67, and powder 68.

[0080] The sampling deadlines for each powder reference tested were 100 hours, 250 hours, 500 hours, and 1000 hours.

[0081] For one reference, four Invar® are tested (one for each period).

[0082] For each sampling, the Invar® blade is removed from the sample holder, cleaned of any remaining traces of powder with a jet of compressed air, and held under vacuum to stop corrosion.

[0083] For each operation, a series of "reference" specimens are added, consisting of Invar® blades placed in powder-free sample holders.

[0084] Immersion of an Invar® blade in the mixtures shown in Table 2 above resulted in the quantified surface corrosion rates shown in Tables 3 and 4.

[0085] Testing of Hydrotalcite [Table 3]

[0086] Polymer-type basic ground anion exchanger test [Table 4]

[0087] In conclusion, this study - The inhibition of corrosivity by fumed silica was demonstrated on Invar® coupons by adding a preloaded ion exchanger to the mixture.

[0088] The insulation units described above can be used in different types of tanks, for example to constitute the primary or secondary insulation barrier in floating structures such as LNG tanks in land-based installations or LNG carriers. In a preferred embodiment, the insulation barrier in which the modular insulation units are used is maintained under vacuum during operation of the tank, i.e. a partial vacuum is created in the space located, for example, between the support wall and the secondary membrane or between the secondary membrane and the primary membrane, to further improve the insulation.

[0089] Referring to FIG. 6 , a terminal for loading / unloading tanks of LNG carriers includes a loading and unloading station 75, an underwater pipeline 76, and an onshore facility 77. The loading and unloading station 75 is a fixed offshore facility including a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 that can be connected to a loading and unloading pipe 73. The adjustable movable arm 74 is adaptable to LNG carriers of all sizes. A connecting pipe (not shown) extends inside the tower 78. The loading and unloading station 75 allows an LNG carrier 70 to load and unload from or to a shore facility 77. It includes a liquefied gas storage tank 80 and a connecting pipe 81 connected to the loading and unloading station 75 by an underwater pipeline 76. The underwater pipeline 76 allows the transfer of liquefied gas between the loading and unloading station 75 and the onshore facility 77 over long distances, for example 5 km, thereby allowing the LNG carrier 70 to be kept at long distances from shore during loading and unloading operations.

[0090] To generate the pressure required for the transfer of liquefied gas, pumps on board the vessel 70 and / or pumps provided at the onshore facility 77 and / or pumps provided at the loading and unloading station 75 are used.

[0091] Although the present invention has been described with reference to some particular embodiments, it is clear that the invention is in no way limited thereto, but includes all technical equivalents of the means described, as well as combinations thereof, if such combinations fall within the scope of the invention.

[0092] Use of the verb "comprise" ("comporter") or "comprendre") and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

[0093] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0094] Although the present invention has been described with reference to some particular embodiments, it is clear that the invention is in no way limited thereto, but includes all technical equivalents of the means described, as well as combinations thereof, if such combinations fall within the scope of the invention.

[0095] Use of the verb "comprise" ("comporter") or "comprendre") and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

[0096] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A thermal insulating modular unit (3, 7) for the thermal insulation of a leaktight tank for the storage of liquids, comprising: The modular units (3, 7) contain insulating fillers, The insulating filler comprises a powdered insulating material containing a main component selected from fumed silica, silica aerogel, and mixtures thereof, and at least one anion exchange compound capable of capturing chloride anions in exchange for the release of at least one other anion; the anion exchange compound is in the form of a powder mixed with the powdered insulating material; A thermal insulating modular unit (3, 7) characterized in that the thermal insulating filling is not enclosed in a gas-impermeable envelope.

2. The anion exchange compound is OH － and CO ３ ２－ 2. The modular unit of claim 1, comprising a group selected from:

3. The anion exchange compound may be clay, layered double hydroxide compound, synthetic hydrotalcite, or an exchangeable anion OH － and CO ３ ２－ 3. The modular unit according to claim 1, wherein the polymer is selected from the group consisting of cross-linked polymers containing:

4. The layered double hydroxide compound is ＩＩ １－ｘ M ＩＩＩ ｘ (OH) ２ ] ｘ＋ [A ｍ－ ｘ／ｍ ・nH ２ O] ｘ－ It is expressed by the formula: M ＩＩ and M ＩＩＩ 4. The modular unit of claim 3, wherein A represents the intermediate layer material, which is a divalent and trivalent cation of the layer, respectively, and A is an anion.

5. 5. A modular unit according to any one of claims 1 to 4, characterized in that the anion exchange compound is in the form of particles with an average apparent size of between 1 μm and 50 μm.

6. 6. A modular unit according to claim 1, wherein the proportion of the anion exchange compound is between 1% and 30% by weight relative to the adiabatic packing.

7. 7. The modular unit according to claim 1, wherein the volume fraction of the anion exchange compound in the insulating packing is less than 5%.

8. 8. The modular unit of claim 1, wherein the modular unit comprises a gas-permeable envelope defining at least one compartment, the insulating filler being disposed within the compartment.

9. 10. The modular unit of claim 8, wherein the gas-permeable envelope comprises a rigid reinforcement including a bottom panel, a cover panel, and a spacing element that holds the bottom panel and the cover panel parallel and spaced apart from each other to absorb pressure.

10. 10. The modular unit of claim 9, wherein the spacing element comprises an interior divider extending between two opposing edges of the bottom panel and between two opposing edges of the cover panel.

11. 10. A modular unit according to claim 9, characterized in that said spacing elements include support posts (57).

12. A modular unit according to any one of claims 1 to 11, characterized in that the insulating filler comprises fibres.

13. A leak-tight insulated tank comprising at least one insulating barrier (2, 6) and a metal leak-tight membrane (5, 9) in contact with the insulating barrier, A leaktight insulated tank, characterized in that the insulating barrier comprises a plurality of modular units (3, 7) according to any one of claims 1 to 12.

14. The leak-tight membrane (5, 9) has a linear thermal expansion coefficient of 2.0×10 from 20° C. to 90° C. －６ K －１ 14. The tank of claim 13, characterized in that it is made of a nickel steel alloy having:

15. The thermal insulation barrier is a secondary thermal insulation barrier (2), the leak-tight membrane is a secondary leak-tight membrane (5); 15. The leaktight insulated tank according to claim 13 or 14, characterized in that the tank further comprises a primary insulating barrier (6) in contact with the secondary leaktight membrane, and a primary leaktight membrane (9) in contact with the primary insulating barrier and configured to be in contact with the fluid contained in the tank.

16. said insulating barrier being a primary insulating barrier (6); the leaktight membrane is a primary leaktight membrane (9) configured to contact the fluid contained in the tank; 15. The leaktight insulated tank according to claim 13 or 14, characterized in that the tank further comprises a secondary leaktight membrane (5) in contact with the primary insulating barrier, and a secondary insulating barrier (2) in contact with the secondary leaktight membrane.

17. Liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon 17. The leaktight insulated tank according to any one of claims 13 to 16, characterized in that it is configured to store a liquid selected from the group consisting of:

18. A vessel (70) for the transportation of liquids, comprising: The ship (70) comprises a double hull (72) and the tank (71) according to any one of claims 13 to 17, which is installed in the double hull.

19. 1. A liquid transfer system comprising: A vessel (70) according to claim 18; an insulated pipe (73, 79, 76, 81) arranged to connect a tank (71) installed in the hull of the ship to a floating or land-based storage facility (77); a pump for driving the flow of liquid through the insulated pipe from the floating or onshore storage facility to the tank on the vessel or from the tank on the vessel to the floating or onshore storage facility; A transfer system comprising:

20. 20. A method of loading or unloading a vessel (70) according to claim 18, comprising the steps of: The method is characterized in that the liquid is transported from a floating or onshore storage facility (77) to the tank (71) of the vessel or from the tank (71) of the vessel to the floating or onshore storage facility (77) via an insulated pipe (73, 79, 76, 81).

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