WO2021180517A1

WO2021180517A1 - Insulating modular unit for leakproof thermally insulating tank

Info

Publication number: WO2021180517A1
Application number: PCT/EP2021/055198
Authority: WO
Inventors: Benoit Morel; Guillaume De Combarieu
Original assignee: Gaztransport Et Technigaz
Priority date: 2020-03-09
Filing date: 2021-03-02
Publication date: 2021-09-16
Also published as: JP2023516788A; FR3107941B1; CN115280059A; KR20220150312A; FR3107941A1

Abstract

The invention pertains to a thermally insulating modular unit (3, 7) for insulating a leakproof liquid storage tank, the modular unit (3, 7) comprising a heat-insulating filling, the heat-insulating filling comprising a pulverulent insulating material containing a principal component selected from fumed silicas, silica aerogels and mixtures thereof and at least one anion exchange compound in the form of a powder mixed with the pulverulent insulating material, where the heat-insulating filling is not enclosed in a gastight casing.

Description

MODULAR INSULATION BLOCK FOR WATERPROOF AND THERMALLY INSULATED TANK

The invention relates to the field of sealed and thermally insulating tanks. The invention relates more particularly to the field of sealed and thermally insulating tanks comprising a metallic waterproofing membrane and a thermally insulating modular block.
The invention also relates to a thermally insulating modular block for the insulation of a sealed tank for the storage and / or transport of a liquid.

Technological background

Document WO-A-2019122757 discloses a thermally insulating barrier for a cold liquid storage tank comprising a plurality of juxtaposed insulating boxes. A box has a compartment and a pulverulent heat-insulating liner disposed in the compartment. The pulverulent packing presents an excellent compromise between a low density and satisfactory thermal insulation performance and is little or not sensitive to an irreversible settlement phenomenon after having been immersed in the liquid stored in the tank. The pulverulent filling is generally chosen from pyrogenic silicas, silica aerogels and mixtures thereof.

Due to their manufacturing processes, these powder fillings consistently contain a small amount of chlorine, approximately 10 parts per million (ppm) or more of chlorine. The solid diffusion of the insulation in the form of dust, either by suspension in the air and displacement with the movement of the latter, or by displacement induced by gravity or by all the accelerations undergone by the ship, can cause contact between the chlorine and the metallic waterproofing membrane, for example made of stainless steel or an alloy with a low coefficient of thermal expansion, in particular an iron and nickel alloy such as INVAR®, and thus cause corrosion by pitting of the waterproofing membrane. Moisture can also carry the chlorine present in the powdery packing and then contact the chlorine with the waterproofing membrane by condensation and cause corrosion of the metal by pitting.

These powdery fillings devoid of the chlorine element are available but their cost is much higher.

In general therefore, for any thermally insulating barrier comprising a gas permeable envelope and comprising a powdery lining chosen from pyrogenic silicas, silica aerogels and their mixture with a small quantity of chlorine, a phenomenon of corrosion of the external structures metal is likely to be observed. This corrosion phenomenon, which weakens the waterproofing membrane, is therefore very damaging depending on the technology used, in particular for sealed and thermally insulating tanks for the storage and / or transport of a liquid.

It is therefore generally necessary to solve this corrosion problem without adversely affecting the thermal insulation performance of the insulating barrier, and thus to develop tanks incorporating thermal insulation barriers permeable to gas, the heat-insulating lining of which is based on pyrogenic silicas, silica airgels and mixtures thereof, and whose outer metal structures sensitive to low concentrations of chlorine no longer corrode.

More specifically, the thermally insulating barrier of liquid storage tanks should be improved, as for example disclosed in FR3075918, to overcome the drawbacks of corrosion observed on metal sealing membranes sensitive to low concentrations of chlorine, such as, for example, alloys of iron and nickel, more precisely the alloy of iron (64%) and nickel (36%) called INVAR®.

The following documents are also known in the field of protection or thermal insulation materials comprising pyrogenic silicas.

Document WO-A-2014184393 describes a composition comprising 40 to 93% of pyrogenic silica or of silica airgel and 5 to 50% of particles having a specific surface, determined by BET, less than or equal to 100 m ² / g. These particles are selected from a large list of products and are chosen for their role of trapping gas molecules in order to delay the rise in internal pressure and thus maintain optimal insulation performance. The size of the pyrogenic silica particles is between 5 nm and 50 nm. The size of the silica airgel particles is between 2 nm and 50 nm or between 50 nm and 2000 nm depending on the manufacturing process. The particles having a specific surface area, determined by BET, less than or equal to 100 m ² / g, alternately have a specific surface area less than or equal to 50 m ² / g, alternately less than or equal to 30 m ² / g. The composition is used for the manufacture of vacuum insulating panels (VIP) which are used in the construction of new buildings and for the insulation of pre-existing buildings as insulation in refrigeration equipment and for the insulation of pipes and tubes. / or machinery in industry.

Document KR-A-20130067712 discloses a flame retardant insulation material comprising 35% to 99.5% by weight of fumed silica having a microporous structure, 0.3 to 25% by weight of a stiffener and 0.2% to 55%. by weight of a heat resistant filler. The stiffener is chosen from glass fibers, ceramic fibers, carbon fibers, quartz fibers and their mixture. The heat resistant filler can be silicon carbide, zirconium silicate, graphite, metakaolin, titanium dioxide, pyrophillite, vermiculite, perlite, calcium silicate and the like.

Document JP-A-2013104491 relates to the field of manufacturing processes for vacuum insulating material. A powder is sealed in a packaging material impermeable to gases under reduced pressure, especially for buildings or freezers or refrigerators. It is indicated that the powder is fumed silica, the average size of the primary particles of which is between 5 and 100 nm and the water content of which is less than 1% by mass. In addition, the powder may contain a gas and moisture adsorbent component such as synthetic zeolite, activated carbon, activated alumina, silica gel, dawsonite, hydrotalcite, and carbon particles. adsorbs chemicals such as oxides and hydroxides of alkali metals and alkaline earth metals.

Abstract

The present invention therefore generally aims to reduce or even eliminate the phenomenon of corrosion of the metallic sealing membrane of a sealed tank incorporating a plurality of thermally insulating modular blocks and comprising a heat-insulating lining mainly based on pyrogenic silicas, silica aerogels and mixtures thereof.

More particularly, the present invention aims to reduce or even eliminate the phenomenon of corrosion of the waterproofing membrane of a sealed and thermally insulating tank, comprising a plurality of modular blocks permeable to gas, and intended to store a liquid chosen from among the Liquefied Natural Gas, Liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon and liquid hydrogen.

A first object according to the present invention relates to a thermally insulating modular block for the insulation of a sealed tank for storing a liquid, the modular block comprising a heat-insulating lining, the heat-insulating lining comprising a pulverulent insulating material comprising a chosen main component. from fumed silicas, silica aerogels and mixtures thereof and at least one anion exchange compound capable of capturing the chloride anion in exchange for the release of at least one other anion, the exchange compound of anion being in the form of a powder mixed with the pulverulent insulating material, the heat-insulating lining not being enclosed in a gas-tight envelope.

The heat-insulating lining can also include fibers, for example glass fibers or carbon fibers. The heat insulating lining may also contain infrared opacifying agents such as SiC, TiO2, graphite or carbon black. The heat-insulating packing can also contain fillers such as perlite in order to limit the settling of the heat-insulating packing, in particular in the event of accidental immersion by liquefied gas.

The following definitions provide a better understanding of the scope of the disclosure.

By “modular block” is meant a solid self-supporting entity, such as a box or a rigid panel, and which can be arranged according to need and the desired number. The geometry can be diverse, cylindrical, parallelepiped or other.

By “pulverulent insulating material” is meant any composition in powder form and which prevents the loss of heat. Such a powder can be packaged in bulk, lightly pressed in a rigid container or in a flexible envelope, or else pressed and densified in the form of blocks or panels sufficiently self-supporting to be handled. Such a powder can also be packaged within a flexible envelope which is itself inserted into a rigid container forming a self-supporting panel suitable for handling. For example, such a powder can be packaged at a density of between 80 kg / m ³ and 500 kg / m ³ depending on the envisaged application and the desired mechanical properties.

The term “anion exchange compound capable of capturing the chloride anion” is understood to mean any chemical compound in the form of a powder having an OH ^- or CO ₃ ^{2− group} and having the capacity to exchange an anion included in its structure. with another chloride anion present in the heat insulating packing. Mention may be made, for example, of clays, lamellar double hydroxide compounds (HDL), synthetic hydrotalcite, crosslinked ion exchange polymers and mixtures thereof. HDL compounds are solid compounds formed from a stack of sheets containing metal cations between which anionic species 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 substituted with trivalent ions, thus giving the plane of octahedra an excess positive charge. In order to ensure overall electrical neutrality, this excess charge is compensated by the negative charges of anions intercalated in the inter-sheet spaces. HDLs employed herein can include hydrated and dehydrated forms. The anion exchange compound may also be able to capture another ionic halogen, for example fluorine, the physical properties of which are close to those of chlorine.

By "sealing membrane" is meant a thin film or sheet of a material consisting of metals or metal alloys to seal the tank against liquid. We can cite, for example, INVAR®.

By “particles having an average apparent size” is meant that the particles have a particle size distribution, the average value of which is thus defined.

The term “mass proportion” is understood to mean mass percentage (% m) to denote the proportion by mass of the component in the total mixture.

By "volume fraction" is meant the volume of the component divided by the sum of the volumes of all the components of the mixture.

By “gas permeable envelope” is meant rigid or semi-rigid or flexible materials defining a closed space. Examples of these gas permeable materials are, for example, wood, damping materials, textile materials, composite materials such as sheet of fiberglass, sheet of polymer fibers, plywood, compressed cardboard. Non-limiting examples of envelopes comprising a rigid frame can be found in particular in documents FR-A-2867831, WO-A-2013017773 and WO-A-2014020257.

In one embodiment, the thermally insulating modular block comprises a gas permeable envelope defining at least one compartment, the heat insulating lining being disposed in said compartment.

In one embodiment, the powdery insulating material contains little or no binder such as an adhesive polymer.

In one embodiment, the proportion of binder used to condition the heat-insulating lining is less than 12% by mass of the heat-insulating lining. For example from 0.3 to 12%. A greater quantity would result in degradation of the thermal insulation performance of the modular block.

In one embodiment, the anion exchange compound is hydrated and includes water molecules.

In one embodiment, the anion exchange compound is chosen from clays, double lamellar hydroxide compounds (HDL), synthetic hydrotalcite (magnesium-aluminum hydroxycarbonate, of chemical composition Mg ₆ Al ₂ (OH) ₁₆ CO ₃ 4H ₂ O), crosslinked anion exchange polymers containing the exchangeable anion OH- or CO32-, for example ion exchanger III (product code 104767 from MERCK®) and mixtures thereof.

In one embodiment, the anion exchange compound has a group chosen from the hydroxide ion (OH ^- ) and the carbonate ion (CO ₃ ^2- ).

In one embodiment, the HDL compound is of the formula [M ^II _1-x M ^III _x (OH) ₂ ] ^{x +} [A ^m- _{x / m} .nH ₂ O] ^x- , wherein MII and MIII are di- and trivalent cations of the sheet, respectively, and A denotes an interfoliar anionic species.

A can be any anion capable of exchanging with the chloride anion present in the heat insulating packing. Preferably, A will not be a halogen anion or a sulfide anion.

In one embodiment, the anionic species A of the HDL compound is chosen from the hydroxide ion (OH ^- ) and the carbonate ion (CO ₃ ^2- ).

By way of example, there may be mentioned different types of HDL minerals suitable according to the invention:
Hydrotalcite of formula Mg ₆ Al ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (rhombohedral type structure)
Manasseite of formula Mg ₆ Al ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (hexagonal type structure)
Meixnerite of formula Mg ₆ Al ₂ (OH) ₁₈ , 4H ₂ O
Pyroaurite of formula Mg ₆ Fe ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (rhombohedral structure)
Sjogrenite of formula Mg ₆ Fe ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (hexagonal type structure)
Coalingite of formula Mg ₁₀ Fe ₂ (OH) ₂₄ CO ₃ , 2H ₂ O
Stichtite of formula Mg ₆ Cr ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (rhombohedral structure)
Barbertonite of formula Mg ₆ Cr ₂ (OH) ₁₆ CO ₃ , 4H ₂ O (hexagonal type structure)
Takovite of formula Ni ₆ Cr ₂ (OH) ₁₆ CO ₃ , 4H ₂ O
Reevesite of formula Ni ₆ Fe ₂ (OH) ₁₆ CO ₃ , 4H ₂ O
Desautelsite of formula Mg ₆ Mn ₂ (OH) ₁₆ CO ₃ , 4H ₂ O.

In one embodiment, the anion exchange compound will be chosen from synthetic hydrotalcite (see example 1), a crosslinked polymer (see example 2), and mixtures thereof.

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.

According to one embodiment, the proportion by mass of the anion exchange compound represents between 1% and 30% by mass of the heat-insulating lining, preferably between 5% and 20% by mass of the heat-insulating lining.

According to one embodiment, the volume fraction occupied by the anion exchange compound within the heat-insulating lining is less than 5%, preferably less than 1%.

According to one embodiment, the casing comprising a rigid frame including a bottom panel, a cover panel and spacers keeping the bottom panel and the cover panel parallel at a distance from each other for take up a pressure force, the spacing elements of the modular block can be produced in various ways.

In one embodiment, the modular block spacers have side walls disposed on edges of the bottom panel and the cover panel, internal partitions extending between two opposite edges of the bottom panel and between two edges. opposites of the cover panel and / or the load-bearing pillars, in particular small-section load-bearing pillars, distributed over an internal surface of the bottom panel and the cover panel.

A second object according to the invention consists of a sealed and thermally insulating tank comprising at least one thermally insulating barrier and a waterproofing membrane resting against said thermally insulating barrier and in which the thermally insulating barrier comprises a plurality of the aforementioned modular blocks.

In an embodiment of the second object according to the invention, the waterproofing membrane is made of a nickel steel alloy with a low coefficient of thermal expansion, that is to say a coefficient of linear thermal expansion (in length) from 20 ° C to 90 ° C less than or equal to 2.0 × 10 ⁻⁶ K ⁻¹ , with K representing the Kelvin. Preferably, the waterproofing membrane is INVAR®, more precisely an alloy of iron (64%) and nickel (36%).

In a particular embodiment, said thermally insulating barrier is a secondary insulating barrier and said waterproofing membrane is a secondary waterproofing membrane, the vessel further comprising a primary thermally insulating barrier resting against the secondary waterproofing membrane and a primary waterproofing membrane resting against said primary insulating barrier and intended to be in contact with the fluid contained in the tank.

In another particular embodiment, said thermally insulating barrier is a primary insulating barrier and said waterproofing membrane is a primary waterproofing membrane intended to be in contact with the fluid contained in the tank, the tank further comprising a membrane secondary waterproofing against which the primary thermally insulating barrier rests and a secondary insulating barrier against which the secondary waterproofing membrane rests.

In one embodiment, the sealed and thermally insulating tank is intended to store a liquid chosen from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon and l liquid hydrogen.

Such a tank can be part of an onshore storage facility, for example to store LNG or be installed in a floating, coastal or deep water structure, in particular an LNG vessel, a floating storage and regasification unit (FSRU). , a floating production and remote storage unit (FPSO) and others. In the case of a floating structure, the tank may be intended for the transport of liquefied gas or to receive liquefied gas serving as fuel for the propulsion of the floating structure, for example in any type of vessel.

According to one embodiment, a vessel for transporting a liquid product comprises a double hull and a above-mentioned tank arranged in the double hull.

According to one embodiment, the invention also provides a method of loading or unloading such a vessel, in which a liquid product is conveyed through isolated pipes from or to a floating or terrestrial storage installation to or from the tank. of the ship.

According to one embodiment, the invention also provides a transfer system for a liquid product, the system comprising the aforementioned vessel, insulated pipes arranged so as to connect the tank installed in the hull of the vessel to a floating storage installation or terrestrial and a pump for driving a flow of liquid product through the insulated pipes from or towards the floating or terrestrial storage installation towards or from the vessel of the vessel.

Brief description of the figures

The invention will be better understood, and other aims, details, characteristics and advantages thereof will emerge more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and not by way of limitation. , with reference to the accompanying drawings, among which:

is a partial cut-away view of a sealed tank wall comprising heat-insulating modular blocks having a rigid wooden casing.

is a schematic perspective representation of a modular heat-insulating block which can be included in the vessel wall of the and which has pillars.

is a perspective view of a modular formwork elements with a plurality of anchoring studs and a load-bearing structure incorporating heat-insulating modular blocks.

is a similar perspective view, similar to the , in which the modular formwork elements were removed and junction insulators were added.

is a sectional diagram of the complete assembly with sample corresponding to the corrosion reduction test of INVAR® described in example 4.

is a cut-away schematic representation of an LNG vessel tank and a loading / unloading terminal for this tank.

With reference to the , we see an area of the double hull of the ship designated by the number 1. The vessel wall is composed successively in its thickness of a secondary insulating barrier 2 which is formed of modular blocks 3 juxtaposed on the double hull 1 and retained on the latter by secondary retaining members 4; then a secondary waterproof membrane 5 carried by the modular blocks 3; then a primary insulating barrier 6 formed by modular blocks 7 juxtaposed and retained on the secondary waterproof membrane 5 by primary retaining members 8 themselves attached to the secondary retaining members 4 and, finally, by a primary waterproof membrane 9 carried by the modular blocks 7. Further details on the structure of the

modular blocks

3 and 7 can be found in the publication FR-A-2867831.

A heat-insulating lining, not shown, packaged in flexible bags or packaged in the form of compacted blocks, fills the interior space of the modular blocks 3 and consists of a mixture of a pulverulent insulating material comprising a main component chosen from among pyrogenic silicas, silica aerogels and mixtures thereof and of at least one anion exchange compound. The anion exchange compound consists of an HDL compound and / or a crosslinked anion exchange polymer containing the exchangeable anion OH ^- or CO ₃ ^2- , for example the crosslinked ion exchange polymer III (product code 104767 from MERCK ®).

With reference to the , according to another embodiment, the modular block 53 comprises a bottom panel 54 on which are fixed distribution flanges 55. A row of

pillars

56 and 60 is supported and is fixed each time on a distribution flange 55 corresponding. In particular, the pillars 57 of each row of

pillar

56 or 60 extend according to the thickness of the modular block 53 and therefore in a direction perpendicular to the supporting wall 1. The pillars 57 have a solid rectangular section. Each row of

pillars

56 or 60 is parallel with respect to a lateral side 58 of the modular block 53. The rows of pillars carry a reinforced cover panel 59. The pillars 57 allow in particular the transmission of the stresses exerted on the cover panel 59 to the wall 1 and have a compressive strength function. Further details on the structure of modular block 53 can be found in publication WO-A-2014020257.

A heat-insulating lining, not shown, packaged in flexible bags or packaged in the form of compacted blocks, fills the space between the pillars 57 and consists of a mixture of a pulverulent insulating material comprising a main component chosen from silicas. pyrogels, silica aerogels and mixtures thereof and of at least one anion exchange compound.

With reference to the , it is described the integration of a thermally insulating modular block in a sealed and thermally insulating tank wall according to one embodiment. Such sealed walls make it possible to produce a containment chamber or vessel for storing and / or transporting a cryogenic fluid, such as a liquefied gas, for example methane. Anchoring studs 11, also called couplers, are regularly positioned and fixed on an external supporting structure 12. This supporting structure 12 can in particular be a self-supporting metal sheet or more generally any type of rigid partition having suitable mechanical properties, such as a concrete wall in a land-based construction. Modular formwork elements 13 are arranged against the supporting structure 12 between the anchoring studs 11. The modular formwork elements 13 thus have a projecting shape, inwardly, relative to the plane of the supporting structure 12. The Modular formwork elements 13 form, with the anchoring studs 11 and the supporting structure 12, a plurality of compartments. The compartments have an open side opposite the supporting structure 12. The modular formwork elements 13 are longitudinal beams arranged perpendicular to each other so as to form compartments having the shape of quadrilaterals at right angles. The modular formwork elements 13 can be equipped with releasable fasteners allowing them to be fixed to the supporting structure 12 and / or to the anchoring studs 11. The compartments are then filled with compressed panels with a heat-insulating lining 15 to through the open side of the compartments in order to form a plurality of insulating sectors made of compressed heat-insulating lining 15. The compartments therefore define a template for the production of said insulating sectors 15.

In one embodiment, short fibers, such as glass fibers, are mixed with the powdery insulation material before forming the compressed panels. In this embodiment, the compressed panels comprise a heat insulating liner including in addition to the powdery insulating material fibers.

The heat-insulating lining, not shown, fills the compartments and consists of a mixture of a pulverulent insulating material comprising a main component chosen from fumed silicas, silica aerogels and mixtures thereof and at least one anion exchange compound.

When the modular formwork elements 13 are removed, the insulating sectors of compressed heat insulating lining 15 are separated by interstices formed by the withdrawal of the formwork elements.

In order to ensure continuity of thermal insulation, said interstices between the insulating sectors of compressed heat-insulating lining 15 are lined with insulating junction elements 18 shown in FIG. 4. The insulating junction elements 18 are also placed at room temperature. , under compressive stress between the insulating sectors of compressed heat-insulating lining 15. Thus, said insulating junction elements 18 are able to relax and fill the gap between the insulating sectors of compressed heat-insulating lining 15 when they contract under the pressure. effect of low temperatures. According to one embodiment, the insulating junction elements 18 are strips made of a flexible material such as glass wool, polyester wadding, polyurethane (PU), melamine, polyethylene (PE) foams, polypropylene (PP) or silicone. The width of these bands is determined such that, at ambient temperature, they undergo a compressive stress between the insulating sectors of compressed heat-insulating lining 15.

The composition as well as the process for preparing the heat-insulating lining intended to form the thermally insulating modular block will be described below.

The heat insulating liner is made from a powdery insulating material comprising hydrophobic fumed silicas, silica aerogels and mixtures thereof and at least one anion exchange compound.

Hydrophobic fumed silicas are available, for example, either under the trade reference AEROSIL R974 or under the trade reference AEROSIL R812S produced by the company Evonik.

Silica aerogels are available for example under the trade reference P100 produced by Cabot Corporation and are ground to a particle size of less than 100 μm.

The heat-insulating lining may further comprise a granular filler consisting of small expanded perlites available under the trade reference CR615 produced by the company KD One Co. or consisting of glass microspheres available under the trade reference Glass Bubble K1 produced by the company 3M or of a granular silica airgel, compatible with liquid nitrogen, known by the trade name P400 produced by Cabot Corporation.

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

Example 2: Preparation of the polymer type anion exchange compound
The anion exchange compound is an ion exchange resin obtained from Sigma Aldrich® under the product reference 104767 and is named Ion exchanger III (strongly basic anion exchanger, OH ^- form) for analysis . It is a powder of a crosslinked polymer with a density of 650-700kg / m ³ . Its particle size is between 496 and 674 μm.

The polymer is placed in a 70 ZPS type impact mill at 16,000 revolutions per minute, the selector of which is set at 8,000 revolutions per minute for an air circulation rate of 80 m ³ / h.

The following table gives the results of the particle size distribution of the powder before and after grinding, measured by a “Mastersizer3000” device from Malvern.

“DXX (v) = A” means that the XX% volume proportion of the particle distribution has a diameter of less than A µm.

A powder is obtained having a particle size of between 1 and 50 μm, with only 10% of the particles having a diameter greater than 19.6 μm.

Example 3: Preparation of anticorrosive pyrogenic linings with chloride anion exchanger

The hydrophobic fumed silica used is of two types:
- silica obtained under the reference AEROSIL® R974 from Evonik Resource Efficiency GmbH with a particle size of less than 200 μm.
- the silica obtained under the reference HDK®H30 obtained from Wacker Chemie AG, which has a particle size of less than 200 μm.

Hydrophobic fumed silica is mixed with hydrotalcite or ground ion exchange resin as shown in Table 2.

Example 4: Test of the reduction of the corrosion of INVAR® by pyrogenic silicas by adding an anion exchanger

The INVAR® alloy is obtained from APERAM IMPHY in the form of hot-rolled strips 0.7 mm thick.

From a strip, samples of 65 mm length and 31.5 mm width are taken. The specimens are free from surface defects. To clean them, they are immersed in 95% ethanol for 15 minutes with the application of ultrasound. The slides are then dried under filtered dry compressed air.

The various experiments indicated in Table 2 below are carried out.

The following accelerated aging protocol is applied. The accelerated aging conditions consist of a temperature of 55 ° C and an ambient humidity of 95% RH . With reference to the , the sample holder comprises a bottle 63, a pierced stopper 64 comprising a stopper lip 65, a filter 66, a test tube of INVAR® 67 and the powder 68.

The collection deadline for each powder reference tested is 100h, 250h, 500h and 1000h.

Four INVAR® specimens per reference are tested (one for each duration).

For each sample, the invar slide is removed from the sample holder and cleaned of residual powder traces by a compressed air jet, then kept under vacuum to stop corrosion.

For each campaign, a series of "Reference" test tubes is added. They consist of INVAR® slides placed in powder-free sample holders.

The immersion of the INVAR® blades in the mixtures indicated in Table 2 above gave the results of the quantification of the surface corrosion rates presented in Tables 3 and 4.

[Table 3]: Hydrotalcite test

[Table 4]: Test of the ground basic anion exchanger of polymer type

In conclusion, this test demonstrated the elimination of the corrosivity of pyrogenic silicas for an INVAR® test tube by adding an ion exchanger preloaded with OH ^- as a mixture.

The insulating blocks described above can be used in different types of tanks, for example to constitute a primary or secondary insulating barrier of an LNG tank in an onshore installation or in a floating structure such as an LNG vessel or the like. In a preferred embodiment, the thermally insulating barrier in which the modular insulating blocks are used is maintained at negative pressure during operation of the tank, i.e. a partial vacuum is created, for example in space. located between the load-bearing wall and the secondary membrane or between the secondary membrane and the primary membrane to further improve thermal insulation.

With reference to the , the loading / unloading terminal of the tank of an LNG vessel comprises a loading and unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and unloading station 75 is a fixed installation off-shore comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipes 73. The movable arm 74 can be swiveled. to all LNG carrier sizes. A connecting pipe (not shown) extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75. The underwater pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a great distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

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

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 comprises all the technical equivalents of the means described as well as their combinations if these come within the scope of the invention.

The use of the verb "to comprise", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

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

Claims

Thermally insulating modular block (3, 7) for insulating a sealed liquid storage tank, the modular block (3, 7) comprising a heat insulating lining, the heat insulating lining comprising a powder insulating material comprising a main component chosen from pyrogenic silicas, silica aerogels and mixtures thereof and at least one anion exchange compound capable of capturing the chloride anion in exchange for the release of at least one other anion, the exchange compound d the anion being in the form of a powder mixed with the pulverulent insulating material,
the heat-insulating packing not being enclosed in a gas-tight envelope.
Modular block according to Claim 1, characterized in that the anion exchange compound has a group chosen from OH - and CO 3 2- .
Modular block according to Claim 1 or 2, characterized in that the anion exchange compound is chosen from clays, lamellar double hydroxide compounds, synthetic hydrotalcite and crosslinked polymers containing the exchangeable anion OH - or CO 3 2- and their mixtures.
Modular block according to Claim 3, characterized in that the double lamellar hydroxide compound is of the formula [M II 1-x M III x (OH) 2 ] x + [A m- x / m .nH 2 O] x- , in which M II and M III are di- and trivalent cations of the sheet, respectively, and A denotes an interfoliar anionic species.
Modular block according to one of claims 1 to 4, characterized in that the anion exchange compound is in the form of particles having an average apparent size of between 1 µm and 50 µm.
Modular block according to one of claims 1 to 5, characterized in that the mass proportion of the anion exchange compound represents between 1% and 30% by mass of the heat-insulating lining, preferably between 5% and 20% by mass of the heat-insulating lining.
Modular block according to one of claims 1 to 6, characterized in that the volume fraction occupied by the anion exchange compound within the heat-insulating lining is less than 5%.
Modular block according to one of claims 1 to 7, characterized in that the modular block comprises a gas permeable envelope defining at least one compartment, the heat-insulating lining being arranged in said compartment.
The modular block of claim 8, wherein the gas permeable shell comprises a rigid frame including a bottom panel, a cover panel and spacers keeping the bottom panel and the cover panel parallel to each other apart. one of the other to resume a pressure effort.
Modular block according to claim 9, characterized in that the spacers have side walls arranged on edges of the bottom panel and the cover panel.
Modular block according to claim 9, characterized in that the spacers have internal partitions extending between two opposite edges of the bottom panel and between two opposite edges of the cover panel.
Modular block according to claim 9, characterized in that the spacing elements comprise supporting pillars (57).
Modular block according to one of claims 1 to 12, characterized in that the heat-insulating lining comprises fibers.
Tight and thermally insulating tank comprising at least one thermally insulating barrier (2, 6) and a metallic waterproofing membrane (5, 9) resting against said thermally insulating barrier and in which the thermally insulating barrier comprises a plurality of modular blocks (3 , 7) according to any one of claims 1 to 13.
Tank according to claim 14, wherein the sealing membrane (5, 9) is made of a nickel steel alloy having a coefficient of linear thermal expansion of 20 ° C to 90 ° C less than or equal to 2.0 × 10 −6 K −1 .
A sealed and thermally insulating vessel according to claim 14 or 15, wherein said thermally insulating barrier is a secondary insulating barrier (2) and said waterproofing membrane is a secondary waterproofing membrane (5), the vessel further comprising a barrier. thermally insulating primary (6) resting against the secondary waterproofing membrane and a primary waterproofing membrane (9) resting against said primary insulating barrier and intended to be in contact with the fluid contained in the tank.
A sealed and thermally insulating vessel according to claim 14 or 15, wherein said thermally insulating barrier is a primary insulating barrier (6) and said sealing membrane is a primary sealing membrane (9) intended to be in contact with the fluid. contained in the tank, the tank further comprising a secondary waterproofing membrane (5) against which the primary thermally insulating barrier rests and a secondary insulating barrier (2) against which the secondary waterproofing membrane rests.
Tight and thermally insulating tank according to one of claims 14 to 17, intended to store a liquid chosen from Liquefied Natural Gas, Liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid argon and liquid hydrogen.
Vessel (70) for transporting liquid, the vessel comprising a double hull (72) and a tank (71) according to one of claims 14 to 18 installed in the double hull.
A transfer system for a liquid, the system comprising a vessel (70) according to claim 19, insulated pipes (73, 79, 76, 81) arranged to connect the vessel (71) installed in the hull of the vessel to a a floating or terrestrial storage facility (77) and a pump for driving a flow of liquid through insulated pipelines from or to the floating or terrestrial storage facility to or from the vessel's tank.
A method of loading or unloading a ship (70) according to claim 20 wherein a liquid is conveyed through insulated pipelines (73, 79, 76, 81) from or to an onshore floating storage facility (77) to or from the vessel (71).