RU2770535C2 - Insulating section for sealed and heat-insulating tank and method for manufacturing such a section - Google Patents

Abstract

FIELD: storage.SUBSTANCE: group of inventions relates to an insulating section for a sealed and heat-insulating tank designed to store wetting liquid. The insulating section contains one compartment and a powder-like insulating filler placed in the mentioned compartment. The insulating filler contains a mixture of x% by weight of powder-like insulating material selected from pyrogenic silica, silica aerogels and mixtures thereof, y% by weight of a granular filler selected from perlites, hollow glass spheres, granules of foamed polymer material and mixtures thereof, wherein x+y ≥ 90%, x ≥ 25% and y ≥ 1%.EFFECT: improvement of heat characteristics of insulating sections for a sealed tank.23 cl, 10 dwg

Description

The field of technology to which the invention belongs

The present invention relates to the field of sealed and thermally insulated tanks for storing and/or transporting fluid.

In particular, the present invention relates to an insulating section for such a sealed and thermally insulating tank and to a method for manufacturing such a box.

BACKGROUND OF THE INVENTION

Document FR 2 877 639 discloses a sealed and thermally insulating tank containing two thermally insulating barriers and two sealed membranes, each of which rests on one of the thermally insulating barriers. Each of the heat-insulating barriers contains a plurality of insulating sections, each of which contains a plurality of compartments filled with an insulating filler selected from polyurethane foam, polyethylene foam and polyvinyl chloride foam and nanoporous materials, for example, airgel, perlite, glass wool or other material. Insulating sections do not quite meet the requirements. In fact, either the prior art insulating cores have a high thermal conductivity, which impairs the thermal insulation performance of the tank and/or requires the provision of thick thermal barriers, or the insulating core has a high density, which also does not satisfy the requirements, in particular due to the need to manipulate the insulating sections. during the manufacture of the tank.

In particular, it is also known from FR 2360536 and WO 2010/068254 or US 3625896 to use pyrogenic silicas or silica aerogels as insulating filler. These materials have excellent thermal insulation characteristics.

However, the Applicant has found that when using fumed silicas and silica aerogels in powder form rather than in compact panels, these materials are unstable and tend to compact upon immersion in a wetting liquid, such as liquefied natural gas (LNG). However, this compaction leads to the formation of thermal bridges. Thus, assuming that the insulating fillers composed of the aforementioned materials in powder form will be immersed in the liquefied natural gas contained in the tank, for example, in the event of a leakage of the sealed membrane of the tank, said insulating fillers will be compacted due to immersion in liquefied natural gas , and hence the thermal performance of the insulation will be irreversibly degraded.

SUMMARY OF THE INVENTION

The idea behind the invention is to provide an insulating section for a sealed and thermally insulated liquid storage tank comprising at least one compartment and a powdered insulating filler placed in said compartment, in which the powdered filler provides an excellent compromise between low density and satisfactory thermal insulation properties. characteristics and less susceptible or not susceptible to the phenomenon of irreversible compaction after immersion in the liquid stored in the tank. The invention also relates to a method for manufacturing such a box section.

In accordance with one embodiment, the invention provides a method for manufacturing an insulating section for a sealed and heat-insulating tank for storing a wetting liquid, the insulating section comprising at least one compartment, the method including the steps of:

preparing a powdered insulating material selected from fumed silicas, silica aerogels and mixtures thereof, said powdered insulating material having:

characteristic size g _x of particles;

a stable true density ϕ _vx for the wetting liquid, which corresponds to the true density of said powdered insulating material having said characteristic particle size g _x after immersion in the wetting liquid; and

a stable apparent density ϕ _ax for the wetting liquid, which corresponds to a threshold apparent density of said powdered insulating material, beyond which the powdered insulating material having a characteristic particle size g _x does not experience compaction after immersion in the wetting liquid; and

a stable apparent density ϕ _ex after compaction, which corresponds to the state of maximum compaction of said powdered insulating material having said characteristic particle size g _x ;

prepare a granular filler selected from perlites, hollow spheres, granules of a foamed polymer material, granular aerogels having an internal degree of porosity that does not decrease after immersion in a wetting liquid, and mixtures thereof, moreover, the granular filler has a characteristic particle size g _y , a stable apparent density ϕ _ay after compaction, which corresponds to the state of maximum compaction of said granular filler having said characteristic particle size g _y and true density ϕ _vy ;

mixing at least a powdered insulating material and a granular filler; moreover, powdered insulating material is present in the mass fraction x, and granular filler is present in the mass fraction y, and: x + y ≥ 90%, x ≥ 25% and y ≥ 1%;

place the mixture in the compartment of the insulating section in a state of compaction, so that:

the true density of the powdered insulating material in the mixture between the grains of the granular filler is less than the aforementioned stable true density ϕ _vx ,

the apparent density of the granular filler in the mixture is less than the stable apparent density ϕ _ay after compaction, and

the apparent density MV _mel of the mixture is greater than or equal to

ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 - y) * ϕ _ay ) and ϕ _ex /[1 - y * (1 - ϕ _ex /ϕ _vy )].

Due to this method of manufacture, the powdered insulating filler provides an excellent compromise between low density and satisfactory thermal insulation performance and is less susceptible or not susceptible to the phenomenon of irreversible compaction after immersion in the liquid stored in the tank.

Due to the presence of the granular filler, the sticking phenomenon of the powdered insulating material after immersion in the wetting liquid is limited, which means that the mixture of the powdered insulating material and the granular filler can remain in powder form without a significant decrease in the volume of the mixture after immersion. In fact, the granular filler helps separate the particles of the powdered insulating material, preventing it from sticking together.

According to one embodiment, the invention also provides an insulating section for a sealed and insulated reservoir for storing a wetting liquid, the insulating section comprising at least one compartment; and

a powdered insulating filler placed in said compartment, wherein the insulating filler contains a mixture of at least:

x% by weight of a powdered insulating material selected from fumed silicas, silica aerogels and mixtures thereof, said powdered insulating material having:

characteristic size g _x of particles;

a stable true density ϕ _vx for the wetting liquid, which corresponds to the true density of said powdered insulating material having said characteristic particle size g _x after immersion in the wetting liquid;

a stable apparent density ϕ _ax for the wetting fluid, which corresponds to a threshold apparent density of said powdered insulating material, beyond which the powdered insulating material having said characteristic particle size g _x does not experience compaction after being immersed in the wetting fluid; and

a stable apparent density ϕ _ex after compaction, which corresponds to the state of maximum compaction of said powdered insulating material having said characteristic particle size g _x ; and

y% by weight of a granular filler selected from perlites, hollow glass spheres, foamed polymer material granules, granular aerogels having an internal degree of porosity that does not decrease after immersion in a wetting liquid, and mixtures thereof, the granular filler having a characteristic particle size g _y , stable apparent density ϕ _ay after compaction, which corresponds to the state of maximum compaction of said granular filler having said characteristic particle size g _y , and true density ϕ _vy ; while x + y ≥ 90%, x ≥ 25% and y ≥ 1%;

moreover, the true density of the powdered insulating material in the mixture is less than the stable true density ϕ _vx ;

the apparent density of the granular filler in the mixture is less than the stable apparent density ϕ _ay after compaction; and

the apparent density MV _mel of the mixture is greater than or equal to

ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 - y) * ϕ _ay ) and ϕ _ex / [1 - y * (1 - ϕ _ex / ϕ _vy )].

In accordance with some embodiments, such a method of manufacturing an insulating section or such an insulating section may contain one or more of the following characteristics:

In accordance with one embodiment, the powdered insulating material and the granular filler are homogeneously mixed by mechanical agitation.

According to one embodiment, the powdered insulating material and the granular filler are compacted until an apparent density MV _mel of the mixture is reached which satisfies the criteria mentioned above.

According to one embodiment, the apparent density of the mixture is less than 250 kg/m ³ , preferably in the range of 50 to 220 kg/m ³ , and more preferably in the range of 60 to 190 kg/m ³ .

According to one embodiment, the mixture has a thermal conductivity of less than 45 mW/(m∙K) at 20°C and normal atmospheric pressure, preferably in the range of 25 to 35 mW/(m∙K) at 20°C and normal atmospheric pressure. pressure.

According to one embodiment, the granular filler has an average particle size in the range of 10 µm to 5 mm, preferably in the range of 20 µm to 2 mm, and more preferably in the range of 25 µm to 1 mm.

According to one embodiment, the granular filler has grains having a mass to external volume ratio of less than 500 kg/m ³ , preferably less than 250 kg/m ³ , more preferably in the range of 30 to 150 kg/m ³ .

In accordance with one embodiment, the granular filler contains expanded perlite.

In accordance with one embodiment, the granular filler comprises hollow spheres made of glass or a polymeric material.

According to one embodiment, the granular fill comprises airgel grains having an internal porosity that does not decrease after immersion in a wetting liquid.

In accordance with one embodiment, the granular filler itself has a thermal conductivity of less than 100 mW/(m*K) at 20° C. and normal atmospheric pressure.

In accordance with one embodiment, the powdered insulating material contains hydrophobic fumed silica.

According to one embodiment, the powdered insulating material has an average particle size of less than 300 microns, preferably less than 200 microns, and more preferably in the range of 2 to 100 microns.

In accordance with one embodiment, x ≥ 50%.

According to one embodiment, y ≥ 5%, preferably y ≥ 10%, and more preferably y ≥ 15%.

In accordance with one embodiment, the insulating filler contains z% by weight of an infrared absorber (IRI), with z < 10%.

In accordance with one embodiment, the insulating part of the mixture, consisting of a powdered insulating material and an ICI absorber, has:

characteristic particle size g _xz ;

a stable apparent density φ _axz that corresponds to a threshold apparent density of said insulating part of the mixture, beyond which said insulating part of the mixture, having a characteristic particle size g _xz , does not experience compaction after immersion in the wetting liquid; and

stable apparent density ϕ _exz after compaction, which corresponds to the state of maximum compaction of the insulating part of the mixture, consisting of powdered insulating material and powdered IKI absorber having the mentioned characteristic particle size g _xz ;

moreover, the apparent density MV _mel of the mixture is also greater than or equal to

ϕ _ay * ϕ _axz / (y * ϕ _axz + (1 - y) * ϕ _ay ) and ϕ _exz / [1 - y * (1 - ϕ _exz / ϕ _vy )].

According to one embodiment, the ICI absorber is an ICI absorbent selected from among others carbon black, graphite, silicon carbide, titanium oxides and mixtures thereof, or any other compound having similar absorbing properties.

In accordance with one embodiment, the average particle size of the ICI absorber is less than 25 microns, and preferably in the range of 3 microns to 20 microns.

In accordance with one embodiment, the apparent density ϕ _ex after compaction is measured in accordance with ISO 787-11:1981.

In accordance with one embodiment, the powdered insulating material has a stable true density ϕ _vx , which is determined in the following way:

immersing a sample of the powdered insulating material in the wetting liquid;

evaporating the wetting liquid from the sample of insulating material;

determining whether the particle size of the powdered insulating material has increased after immersion and evaporation of the wetting liquid; and

if the particle size of the insulating material has increased, measure with a pycnometer the true density of the sample of powdered insulating material after immersion and evaporation of the wetting liquid, and the stable true density ϕ _vx corresponds to the measured true density; a

if an increase in the particle size of the insulating material is not observed, determine the stable true density ϕ _vx of the powdered insulating material sample by measuring the stable apparent density ϕ _ax of the sample, and the stable true density ϕ _vx of the insulating material is equal to the stable apparent density ϕ _ax of the sample.

According to one embodiment, said pulverulent insulating material has a stable apparent density ϕ _ax , which is determined in the following way:

placing a sample of the powdered insulating material into the cavity of the container;

measuring the height of the sample of powdered insulating material in the cavity;

immersing the container in the wetting liquid so that the sample of powdered insulating material is completely saturated with the wetting liquid;

evaporating the wetting liquid;

measuring the height of the sample of powdered insulating material in the cavity after immersion and evaporation of the wetting liquid;

determine the height change of the sample of powdered insulating material in the cavity before and after immersion;

determine the apparent density of the powdered insulating material after immersion and evaporation of the wetting liquid, if the change in the height of the volume of the powdered insulating material in the cavity before and after immersion is less than or equal to 2% of the initial height; moreover, the stable apparent density ϕ _ax corresponds to the measured apparent density.

In accordance with one embodiment, the granular filler has a stable apparent density ϕ _ay after compaction, which is determined in the following way:

compacting the granular filler by shaking until it reaches a state of maximum compaction;

determine the apparent density of the granular filler after compaction, and the stable apparent density ϕ _ay after compaction corresponds to the measured apparent density.

According to one embodiment, the stable apparent density ϕ _ex after compaction of the powdered insulating material is determined by the following method:

compacting the powdered insulating material by shaking until it reaches a state of maximum compaction;

determine the apparent density of the granular filler after compaction, and the stable apparent density ϕ _ex after compaction corresponds to the measured apparent density.

In accordance with one embodiment, the apparent density of the powdered insulating material in the mixture between the grains of the granular filler is less than the stable apparent density ϕ _ax of the powdered insulating material. This means that the density of the powdered insulating material can be limited, making the section easier to handle.

According to one embodiment, the insulating section comprises a bottom panel, a cover panel, and walls extending between the bottom panel and the cover panel and forming at least one compartment.

According to one embodiment, the wetting liquid is a cryogenic liquid.

In accordance with one embodiment, the wetting fluid is selected from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid nitrogen, liquid air, liquid argon, liquid xenon, liquid neon, and liquid hydrogen.

In accordance with one embodiment, the invention also provides a sealed and thermally insulating reservoir, containing at least one thermal barrier and a sealing membrane intended for contact with the fluid contained in the reservoir adjacent to said thermal barrier, in which the thermal barrier contains a plurality of insulating sections described above.

Such a reservoir may form part of an onshore storage facility, for example for LNG storage, or may be installed on a floating structure, onshore or deep water, such as a methane tanker, a floating gas regasification and storage unit (FSRU), a floating production unit, oil storage and offloading (FPSO) and other structures.

In accordance with one embodiment, the fluid tanker comprises a double hull and a reservoir as described above located in the double hull, the double hull comprising an inner shell forming the supporting structure of the reservoir.

In accordance with one embodiment, the invention also provides a method for loading or unloading such a tanker, in which fluid is supplied through insulated pipelines from floating or shore storage to the tanker tank or vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become better understood and other objects, details, characteristics and advantages will become more apparent from the following description of several specific embodiments of the invention, given solely by way of non-limiting illustration and with reference to the accompanying drawings, in which:

Fig. 1 is a simplified perspective view of a tank wall in accordance with one embodiment.

Fig. 2 is a schematic view of equipment for determining the stable true density ϕ _vx of a powdered insulating material for a given wetting liquid.

Fig. 3 is a schematic view of equipment for determining the stable apparent density ϕ _ax of a powdered insulating material for a given wetting liquid.

Fig. 4 is a graph illustrating the stability range when immersed in liquid nitrogen of a mixture of expanded perlite from the first batch and hydrophobic fumed silica.

Fig. 5 is a graph illustrating the range of stability when immersed in liquid nitrogen of a mixture of glass microspheres and hydrophobic fumed silica.

Fig. 6 is a graph illustrating the range of stability when immersed in liquefied natural gas for a mixture of expanded perlite from the first batch and hydrophobic fumed silica.

Fig. 7 is a graph illustrating the range of stability when immersed in liquefied natural gas for a mixture of second batch expanded perlite and hydrophobic fumed silica.

Fig. 8 is a graph illustrating the range of stability when immersed in liquid nitrogen of a mixture of granular airgel and hydrophobic fumed silica.

Fig. 9 is a simplified schematic view of a methane tanker tank and a tank loading/unloading terminal.

Fig. 10 is a graph illustrating the stability range when immersed in liquefied natural gas of a mixture of expanded perlites from the first batch with a powder consisting of a mixture of another crushed granular airgel and hydrophobic fumed silica.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 illustrates the wall of a sealed and thermally insulated tank. The sealed and thermally insulated tank is designed to store a wetting liquid, which, for example, is selected from liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquid methane, liquid ethane, liquid propane, liquid nitrogen, liquid air, liquid argon, liquid xenon , liquid neon and liquid hydrogen.

In the direction from the outer side to the inner side of the tank, the tank wall contains a supporting structure 1, an auxiliary heat-insulating barrier 2, which is formed by adjacent insulating sections 3 on the supporting structure 1 and attached to it by auxiliary retaining means 4, an auxiliary sealing membrane 5 supported by insulating sections 3, a main thermal barrier 6 formed by adjacent insulating sections 7 and attached to the secondary sealing membrane 5 by main retaining means 8, and a main sealing membrane 9 supported by insulating sections 7 and designed to come into contact with the liquid contained in the tank.

The supporting structure 1 may in particular be a self-supporting metal sheet, or more generally, it may be any type of rigid partition having suitable mechanical properties. The supporting structure may in particular be formed by the hull or double hull of the tanker. The supporting structure contains a plurality of walls that define the overall shape of the tank.

The main 9 and auxiliary 5 sealing membranes, for example, are formed by a continuous sheet of metal strips with protruding edges, and said strips are welded with their protruding edges to parallel welded supports held on insulating sections 3, 7.

Each insulating section 3, 7 has the shape of a substantially rectangular parallelepiped. Each insulating section 3, 7 includes a bottom panel and a cover panel that are parallel to each other. Between the bottom panel and the cover panel there are several bearing partitions perpendicular to them. The load-bearing partitions are arranged parallel to each other and form compartments between them to accommodate the powdered insulating filler. Each insulating section 3, 7 additionally comprises two closing side walls located perpendicular to the load-bearing partitions on both sides of the row of load-bearing partitions so as to close the compartments in which the powdered insulating filler is placed.

Below will be described the composition, as well as the method of manufacturing a powdered insulating filler, which is intended for placement in the compartments of the insulating sections 3, 7.

Powdered insulating filler consists of a mixture containing:

mass fraction x% of powdered insulating material selected from fumed silicas, silica aerogels and mixtures thereof;

mass fraction y% of granular filler selected from perlites, hollow glass or polymeric spheres, granules of foamed polymer material, granular aerogels and mixtures thereof; and

additionally, if necessary, the mass fraction z% of the ICI absorber and/or other possible additive(s);

and:

x + y ≥ 90%,

x ≥ 25%; and preferably ≥ 50%; and

y ≥ 1%, preferably ≥ 5%, more preferably ≥ 10% and even more preferably ≥ 15%.

The powdered insulating material and granular filler are chosen to be chemically resistant to the wetting liquid stored in the tank. In other words, the wetting liquid intended to be stored in the tank cannot chemically degrade the powdered insulating material, the granular filler, and in general any other component of the powdered insulating filler.

The physical properties of the powdered insulating material and granular filler, as well as the density of the mixture, are carefully determined to obtain an insulating filler that has:

a thermal conductivity of less than 45 mW/(m∙K) at 20°C and normal atmospheric pressure, and preferably in the range of 25 to 35 mW/(m∙K);

an apparent density of the mixture of less than 220 kg/m ³ , preferably in the range of 50 to 215 kg/m ³ and more preferably in the range of 60 to 190 kg/m ³ ; and

which is not susceptible or only marginally susceptible to the phenomenon of irreversible compaction after immersion in a wetting liquid stored in a tank.

The powdered insulating material consists of oxides having fractal microstructures, such as fumed silicas, silica aerogels and mixtures thereof.

According to a preferred embodiment, the particulate insulating material is hydrophobic. This is particularly advantageous when the insulating material may be exposed to water, such as when the tank is intended to be placed on board a tanker.

The powdered insulating material has a certain characteristic particle size g _x . In particular, the average particle diameter of the powdered insulating material is less than 300 µm, preferably less than 200 µm, and more preferably in the range from 2 to 100 µm, for example, about 40 µm.

Furthermore, for said characteristic particle size g _x , the powdered insulating material has a certain stable true density ϕ _vx , a certain stable apparent density ϕ _ax and a certain stable apparent density ϕ _ex after compaction. These characteristics of the powdered insulating material make it possible to determine the state of compaction in which the powdered insulating filler should be placed in the compartment of the insulating section 3, 7.

The stable true density ϕ _vx of a powdered insulating material for a given wetting liquid corresponds to the true density of a powdered insulating material having said particle size after said powdered insulating material is completely immersed in the wetting liquid in question and the liquid has evaporated.

The true volume of the powdered insulating material (in m ³ ) can be defined as the sum of the elementary volumes of the particles, including the volume of open and closed pores of the particles. The true density of the powdered insulating material (in kg/m ³ ) can be defined as the mass of the powdered insulating material corresponding to a unit of true volume of the powdered insulating material.

Below with reference to FIG. 2 describes the equipment and method for determining the stable true density ϕ _vx of a powdered insulating material for a given wetting liquid.

First, a sample of the powdered insulating material 10 whose stable true density ϕ _vx is to be determined is completely impregnated with the wetting liquid, and then the wetting liquid is evaporated. Immersion may have the effect of changing the particle size of the sample of powdered insulating material 10, since the particles may stick together due to immersion in the wetting liquid. Thus, due to the adhesion of particles, the volume of open pores will decrease so that the true density of the powdered insulating material will increase.

If the phenomenon of particle size change due to sticking occurs, the stable true density ϕ _vx is determined as follows.

A sample of powdered insulating material 10 having a certain mass m _x is placed in a pycnometer 11 having a known volume V _p and an empty mass M _v . Next, the pycnometer 11 is connected through a tight connection 12 to a three-way valve 13, which is able to selectively connect two of the three lines leading respectively to the pycnometer 11, to a reservoir 14 for a liquid that is non-wetting with respect to the powdered insulating material under test, and to a vacuum pump 15 A liquid which is non-wetting with respect to the insulating powder under test has a specific density ϕ _L and is, for example, mercury or water if the insulating powder under test is hydrophobic.

Then the channels 17, 18 leading respectively to the tank 14 and the vacuum pump 15 are connected to each other to fill the channel 17 connecting the tank 14 with the three-way valve 13 with a non-wetting liquid. Next, the line leading to the vacuum pump 15 is connected to the pycnometer 11 for evacuation of the pycnometer 11, as well as the pipeline 16 connecting the pycnometer 11 to the three-way valve 13. Then the pipeline 17 leading to the reservoir 14 and the pipeline 16 leading to the pycnometer 11 are connected with each other until the pycnometer 11 is completely filled with non-wetting liquid. After that, the tight connection 12 can be disconnected.

By measuring the total mass M _t of the pycnometer 11 in the fully filled state, the stable true density ϕ _vx can be determined using the following formula:

where:

m _x : mass of the sample of powdered insulating material placed in the pycnometer;

V _p : pycnometer volume;

M _t : total mass of the pycnometer when fully filled;

M _v : empty mass of the pycnometer; and

ϕ _L : density of the non-wetting liquid.

In addition, the stable apparent density ϕ _ax of the powdered insulating material for a given wetting liquid corresponds to the threshold apparent density of the powdered insulating material, beyond which the powdered insulating material having said characteristic particle size does not experience compaction after complete immersion of said powdered insulating material in the wetting liquid in question. and liquid evaporation.

If the particle size change phenomenon due to sticking after immersion in the wetting liquid does not occur, the stable true density ϕ _vx does not differ from the stable apparent density ϕ _ax measured using the method described below. In other words, if the phenomenon of change due to sticking after immersion in the wetting liquid does not occur, it can be considered that there is little or no interstices between the particles of the granular filler.

In fact, if the particle size of the powdered insulating material is not increased, the measurement of true density by means of a pycnometer may change the sticking state of the particles and thereby cause an error in the measurement of true density ϕ _vx . In other words, in the case of an increase in particle size, two levels of porosity are taken into account, namely, interparticle porosity and intraparticle porosity; whereas, in the absence of an increase in particle size, the porosity is considered to be completely uniform and can be considered as intraparticle porosity. The apparent volume (in m ³ ) of the powdered insulating material can be defined as the volume occupied by said powdered insulating material and combining the volume of particle material, open porosity volumes, closed porosity volumes, as well as interstices between particles. The apparent density of the powdered insulating material (in kg/m ³ ) can be defined as the mass of the powdered insulating material corresponding to a unit of apparent volume of the powdered insulating material.

Below with reference to FIG. 3 describes the equipment and method for determining the stable apparent density ϕ _ax of a powdered insulating material for a given wetting liquid.

The equipment includes a container 18 designed to be immersed in the wetting liquid in question and forming an internal cavity designed to receive a sample 19 of powdered insulating material. The container 18 is preferably made of a material having a coefficient of thermal expansion less than or equal to 10×10 ^-6 K ^-1 . The material used is, for example, birch plywood.

The cavity formed by the container 18 has the shape of a rectangular parallelepiped, the dimensions of which are determined. The width, length and height of the cavity are at least 150 mm, 150 mm and 300 mm, respectively. Each of the six walls of the container 18 has a plurality of holes 20 which allow the wetting fluid to pass through said walls. The inner surface of the walls of the container 18 is covered with a liquid-permeable fabric. The fabric 21 has a mesh size smaller than the particle size of the insulating powder, so that the insulating powder cannot pass through said fabric 21.

The container 18 includes a removable lid 22 to allow a sample 19 of powdered insulating material to be placed inside the container 18.

A sample 19 of powdered insulating material having a certain mass m _x , whose stable apparent density ϕ _ax is to be determined, is placed inside the container. The original powdered insulating material is in a state of compaction, so that its apparent density is less than the stable apparent density ϕ _ax . The minimum height of the sample 19 of powdered insulating material inside the container is greater than or equal to 15 cm.

The empty space between the test sample 19 of the powdered insulating material and the removable cover 22 is filled with a foam block 23 which is permeable to the wetting liquid but does not allow the passage of the powdered insulating material. The foam block 23 is made of, for example, melamine resin, such as Basotect G® foam. The foam block 23 is positioned so that it does not collapse between the lid 22 and the powdered insulation material 19 when the container 18 is closed.

Next, the container 18 containing the sample 19 of the powdered insulating material is immersed in the wetting liquid for a period of time sufficient to allow the powdered insulating material to be completely saturated with the wetting liquid.

In accordance with one embodiment, a temperature sensor 24 is placed at a distance of approximately 1 cm from the top of the sample 19 of the powdered insulating material, and the immersion period is determined depending on the temperature measurement provided by the temperature sensor 24. In accordance with one possible embodiment, during immersion, the level of the wetting liquid is maintained at the level of the upper boundary of the sample 19 of powdered insulating material. Thus, when the temperature provided by the temperature sensor 24 is equal to the temperature of the wetting liquid, it confirms that the entire portion of the insulating material sample 19 located below the temperature sensor 24 has been impregnated. To ensure proper impregnation of the entire sample 19 of powdered insulating material, the level of the wetting liquid is raised beyond the upper limit, and the assembly is left immersed for an additional period equal to at least 50% of the time necessary to equalize the temperature provided by the temperature sensor 24 and the temperature of the wetting liquid , counting from the start of the dive. As an example, the total operation time for testing on fumed silicas impregnated with liquid nitrogen is on the order of 3 hours.

In accordance with one embodiment, the impregnation of the sample 19 with powdered insulating material is not monitored by the temperature sensor 24, and the container 18 is immersed in the wetting liquid for a sufficient period of time, determined during the experiment. As an example, container 18 may remain immersed in liquefied natural gas for two weeks.

After immersion, container 18 is placed in an environment that allows complete evaporation of the wetting liquid without causing container 18 to decompose.

The above steps are repeated until the change in the height of the test sample 19 of the powdered insulating material before and after impregnation and subsequent evaporation of the wetting liquid becomes less than or equal to 2% of the initial height. If the change in height is less than the above value, the sample 19 of the powdered insulating material has reached a stable apparent density ϕ _ax . The stable apparent density ϕ _ax corresponds to the mass of the sample 19 of the powdered insulating material placed in the container 18 divided by the volume of the container 18 occupied by said sample 19 of the powdered insulating material.

The measurement of apparent density inside the container is carried out in accordance with the protocol described in ISO 787-11:1981 "General methods of test for pigments and extenders - Part 11: Determination of apparent density and stable apparent density after tamping [compaction]", and graduated the 250 ml measuring cylinder mentioned in the said standard is replaced with a container, and the measurement of the height of the powdered insulating material is performed at a plurality of points with a ruler.

A powdered insulating material having said characteristic particle size g _x also has an apparent density ϕ _ex after compaction, which is measured in accordance with ISO 787-11:1981 "General methods of test for pigments and extenders - Part 11: Determination of apparent density and stable apparent density after tamping [compaction]".

The granular filler is selected from perlites, hollow spheres, polymeric foam granules, granular aerogels and mixtures thereof.

If the granular fill contains granular aerogels, they are chosen so that their internal porosity does not decrease after immersion in the wetting liquid.

According to one preferred embodiment, the granular filler consists of expanded perlite.

The granular filler has a certain characteristic particle size g _y . In particular, the average particle diameter of the granular filler is in the range of 10 µm to 5 mm, preferably in the range of 20 µm to 2 mm, and more preferably in the range of 25 µm to 1 mm, for example about 300 µm.

Preferably, the granular filler has grains having a mass to external volume ratio of less than 500 kg/m ³ , preferably less than 200 kg/m ³ , more preferably in the range of 50 to 150 kg/m ³ .

More preferably, the granular filler itself has a thermal conductivity of less than 100 mW/(m∙K) at 20°C and normal atmospheric pressure.

The granular filler has a stable apparent density ϕ _ay after compaction, corresponding to the state of maximum compaction that a granular filler having said characteristic particle size g _y can achieve. In other words, the stable apparent density ϕ _ay after compaction of the granular filler corresponds to the maximum apparent density that the granular filler can achieve without changing the particle size of said granular filler, in particular by grinding. The apparent volume (in m ³ ) of the granular filler can be defined as the volume occupied by the granular filler and combining the particle material volume, the open porosity volumes, the closed porosity volumes, and the spaces between the particles. Thus, the apparent density of the powdered insulating material (in kg/m ³ ) can be defined as the mass of the powdered insulating material corresponding to a unit of the apparent volume of the powdered insulating material.

The stable apparent density ϕ _ay after compaction of the granular filler is determined, for example, according to the protocol described in ISO 787-11:1981 "General methods of test for pigments and extenders - Part 11: Determination of apparent density and stable apparent density after tamping [compaction]", after bringing the granular filler to a state of maximum compaction during compaction operations by shaking.

In addition, the granular filler has a true density ϕ _vy . To determine the true density ϕ _vy use the following method. The method is particularly suitable for open porosity aggregates and is specifically mentioned in paragraph 3.2.3.3 of article C2210V2 "Formulation des bétons" [Formulation of concretes], published May 10, 2004 in the Techniques de l'Ingénieur [Engineering Techniques].

First, the theoretical density of the test lot is determined. To do this, first determine the particle size distribution of the test batch by sieving. The theoretical density C _m for n particle size classes can be determined using the following relationships:

where:

and:

n: particle size classes and 1 ≤ i ≤ n;

C _i : density class i;

y _i : volume fraction of class i;

_aij :

b _ij :

d _i : diameter of class i grains.

Next, determine the true density ϕ _vy using the following relationship:

In the case of a closed-cell filler, such as hollow glass spheres, it is preferable to use the method described in ISO 12154:2014 April 2014 "Determination of density by volumetric displacement - skeleton density by gas pycnometry". In this method, the true density φ _vy of the granular filler is measured with a gas pycnometer using, for example, nitrogen as the gas introduced into the pycnometer.

The Applicant has found that the powdered insulating filler has a low density and yet is not susceptible to the phenomenon of irreversible compaction after immersion in the wetting liquid in question, when the mixture is placed in the compartment of the insulating section in a state of compaction, so that:

the true density of the powdered insulating material in the mixture is less than the said stable true density ϕ _vx ,

the apparent density of the granular filler in the mixture is less than the stable apparent density ϕ _ay after compaction, and

the apparent density MV _mel of the mixture is greater than or equal to ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 - y) * ϕ _ay ) and ϕ _ex /[1 - y * (1 - ϕ _ex /ϕ _vy )].

In addition, preferably, in order to limit the density of the powdered insulating material, the apparent density of the powdered insulating material in the mixture between the grains of the granular filler is less than the stable apparent density ϕ _ax of the powdered insulating material.

In order to obtain a homogeneous mixture having an apparent density MV _mel that satisfies the criteria mentioned above, the powdered insulating material and granular filler are mixed by mechanical mixing, then placed in the compartments of the insulating section, after which the mixture is mechanically compacted in the compartments of the insulating section until the mixture will not be flush with the top end of the compartments of the insulating section and will not reach the target apparent density MV _mel meeting the criteria mentioned above.

EXAMPLES

Several examples of powdered insulating fillers, consisting of a mixture of one of the above powdered insulating materials and one of the above granular fillers, were subjected to compaction tests after immersion in liquefied natural gas (LNG) or liquid nitrogen (LN ₂ ) and thermal conductivity measurements.

Powdered insulating fillers were made from a powdered insulating material consisting of hydrophobic fumed silicas available either under the trade name AEROSIL R974 or under the trade name AEROSIL R812S manufactured by Evonik and/or silica airgel known under the trade name P100 manufactured by Cabot. Corporation and ground to a particle size of less than 100 microns, and granular filler consisting of expanded perlite available under the trade name CR615 manufactured by KD One Co. or consisting of glass microspheres available under the trade name Glass Bubble K1 manufactured by 3M , or from liquid nitrogen compatible granular silica airgel known under the trade name P400, manufactured by Cabot Corporation.

The characteristics of powdered insulating materials were as follows:

Nature Name Particle size (µm) Stable apparent density ϕ _ex after compaction (kg/m ³ ) Stable apparent density ϕ _ax for LN ₂ (kg/m ³ ) Stable apparent density ϕ _ax for LNG (kg/m ³ ) Stable true density ϕ _vx for LN ₂ (kg/m ³ ) Stable true density ϕ _vx for LNG (kg/m ³ ) Hydrophobic fumed silica Aerosil R974 51 112 180 172 215 Hydrophobic fumed silica Aerosil R812S <200 59.9 173 230 Hydrophobic fumed silica as a mixture with crushed airgel Composition A, consisting of AEROSIL R974 (25% by weight) and milled AEROGEL P100 (25% by weight) <200 55 175 234

The characteristics of the granular fillers were as follows:

Particle size (µm) Stable apparent density ϕ _ay after compaction (kg/m ³ ) Nature Name Stable true density (kg/m ³ ) <1000 57.5 expanded perlite CR615 batch 1 73.1 <1000 65.6 expanded perlite CR615 batch 2 82.2 <120 77 Glass microspheres Glass Bubble K1 129.7 <3000 91.9 Granular silica airgel compatible with liquid nitrogen P400 143

The particle size distribution of CR615 perlite batches, by weight, was as follows:

Particle size >800 µm 500-800 µm 250-500 µm 160-250 µm 63-160 µm <63 µm Distribution CR615 batch 1 8.4% 29.6% 31.3% 8.7% 12.8% 9.2% Distribution CR615 batch 2 7.0% 16.8% 20.1% 7.8% 30.7% 17.6%

The particle size distribution of P400 granular airgel, by weight, was as follows:

Particle size >2 mm 1.7-2mm 1.4-1.7mm 1-1.4mm 710 µm-1 mm 425-710 µm 425-160 µm 63-160 µm <63 µm Distribution 3.6% 6.0% 12.8% 28.6% 19.2% 18.1% 10.1% 1.4% 0.2%

The particle size distribution of glass microspheres, by volume, available under the trade name Glass Bubble K1 manufactured and provided by 3M was as follows:

Particle size >115 µm 65-115 µm 30-65 µm <30 µm Distribution ten% 40% 40% ten%

Example 1

Prepared six mixtures of expanded perlite CR615, batch 1, and hydrophobic fumed silica AEROSIL R974, having different weight fractions and/or apparent density MV _mel . The six mixtures were then completely immersed in liquid nitrogen, followed by a liquid nitrogen evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained.

Mixture CR615 Batch 1 (y% by weight) AEROSIL R974 (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion Altitude change
%* Apparent density MV _mel of the mixture (kg/m ³ ) after immersion ϕ _ay * ϕ _ax /(y * ϕ _ax + *(1 - y) * ϕ _ay ) in (kg/m ³ ) one 5 95 200.6 105.0 202.3 +0.8 104.1 106.9 2 ten 90 200.1 98.1 200.2 +0.0 98.1 102.3 3 25 75 168.4 80.7 156.4 -7.1 86.9 90.5 4 25 75 190.7 90.2 190.3 -0.2 90.4 90.5 5 fifty fifty 163.8 83.7 177.9 +8.6 77.1 76 6 fifty fifty 204.3 77.6 205.4 +0.5 77.2 76

*: Conventionally, the increase in height is indicated by positive values, and the decrease in height - by negative values.

Tests have shown that, within measurement accuracy, the lower limit of the apparent density MV _mel of the stable mixture after immersion was along the curve defined by the above mentioned function ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 - y) * ϕ _ay ), and always higher than the function ϕ _ex /[1 - y * (1 - ϕ _ex /ϕ _vy )].

The stability range as well as the test results are shown in FIG. 4, in which the weight fraction of AEROSIL R974 is shown on the abscissa. For each of these examples, the apparent density MV _mel of the mixture (kg/m ³ ) before immersion is indicated by a triangle, while the apparent density MV _mel of the mixture (kg/m ³ ) after immersion is indicated by a circle. The stability range of the mixture when immersed in liquid nitrogen is shaded.

Example 2

In addition, a thermal conductivity test was performed on a mixture containing 25% by weight of expanded perlites CR615 batch 1 and 75% by weight of hydrophobic fumed silicas AEROSIL R974 and having an apparent density MV _mel of 91 kg/m ³ before and after immersion.

The thermal conductivity of the mixture was measured as a function of pressure and temperature before and after immersion in liquid nitrogen. The table below shows the thermal conductivity (in mW/(m∙K)) of the mixture. Obviously, such a mixture has a low thermal conductivity.

Absolute pressure (mbar) T (°C) one ten 100 980 Before the dive 20 6 nine 17 29 -80 21 -160 2 5 ten fourteen After the dive 20 7 12 eighteen thirty -80 21 -160 3 6 ten fourteen

Example 3

Prepared four mixtures of glass microspheres Glass Bubble K1 and hydrophobic pyrogenic silica AEROSIL R974, having different mass fractions and/or apparent density MV _mel . The mixtures were then completely immersed in liquid nitrogen, followed by a liquid nitrogen evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained.

Mixture Glass Bubble K1 (y% by mass) AEROSIL R974 (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Altitude change
in % Apparent density MV _mel of the mixture (kg/m ³ ) after immersion ϕ _ay * ϕ _ax / (y * ϕ _ax + (1 -y) * ϕ _ay ) in
(kg/m ³ ) one 25 75 201.1 87.7 192.4 -4.3 91.7 100.6 2 25 75 200.4 99.5 202.4 +1.2 98.5 100.6 3 fifty fifty 205.3 89.0 200.8 -2.2 91 91.3 4 fifty fifty 195.4 97.6 200.7 +2.7 95 91.3

The stability range as well as the test results are shown in Figure 5, in which the weight fraction of AEROSIL R974 is shown on the abscissa. For each of these examples, the apparent density MV _mel of the mixture (kg/m ³ ) before immersion is indicated by a triangle, while the apparent density MV _mel of the mixture (kg/m ³ ) after immersion is indicated by a circle. The stability range of the mixture when immersed in liquid nitrogen is shaded.

Example 4

Prepared five mixtures of expanded perlites CR615, lot 1, and hydrophobic fumed silicas AEROSIL R974, having different weight fractions and/or apparent densities MV _mel . The four blends were then completely immersed in liquefied natural gas, followed by an liquefied natural gas evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained.

Mixture CR615 Batch 1 (y% by weight) AEROSIL R974 (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Height change in % Apparent density MV _mel of the mixture (kg/m ³ ) after immersion ϕ _ay * ϕ _ax / (y * ϕ _ax + (1-- y) * ϕ _ay ) in (kg/m ³ ) one ten 90 194.7 145.0 195.0 +0.2% 144.7 142.2 2 25 75 199.1 117.96 201.4 +1.2% 116.6 114.2 3 25 75 202.7 103.1 183.0 -9.7% 114.2 114.2 4 fifty fifty 294.8 82.2 292.8 -0.7% 82.8 85.9 5 5 95 165.9 158.4 169.4 +2.1 155.1 154.9

The tests allowed to confirm, within the limits of measurement accuracy, the lower limit of the apparent density MV _mel of a stable mixture after immersion in liquefied natural gas.

The stability range as well as the test results are shown in FIG. 6, in which the weight fraction of AEROSIL R974 is shown on the abscissa. For each of these examples, the apparent density MV _mel of the mixture (kg/m ³ ) before immersion is indicated by a triangle, while the apparent density MV _mel of the mixture (kg/m ³ ) after immersion is indicated by a square. The range of mixture stability when immersed in liquefied natural gas is shaded.

Example 5

Four mixtures were prepared from expanded perlites CR615, lot 2, and hydrophobic fumed silicas AEROSIL R812S, having different weight fractions and/or apparent densities MV _mel . The four blends were then completely immersed in liquefied natural gas, followed by an liquefied natural gas evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained:

Mixture CR615 Batch 2 (y% by weight) AEROSIL R812S (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Height change in % Apparent density MV _mel of the mixture (kg/m ³ ) after immersion ϕ _ay * ϕ _ax / (y * ϕ _ax + (1 - y) * ϕ _ay ) in (kg/m ³ ) one 25 75 168.4 115.4 160.6 -4.6 121.0 122.8 2 25 75 157.6 126.0 159.0 +0.9 124.9 122.8 3 fifty fifty 204.0 91.0 192.3 -5.7 96.5 95.1 4 fifty fifty 183.9 101.4 187.0 +1.7 99.7 95.1

The tests allowed to confirm, within the limits of measurement accuracy, the lower limit of the apparent density MV _mel of a stable mixture after immersion in liquefied natural gas.

The stability range as well as the test results are shown in FIG. 7, in which the mass fraction of AEROSIL R812S is shown on the abscissa. For each of these examples, the apparent density MV _mel of the mixture (kg/m ³ ) before immersion is indicated by a triangle, while the apparent density MV _mel of the mixture (kg/m ³ ) after immersion is indicated by a square. The range of mixture stability when immersed in liquefied natural gas is shaded.

Example 6

In addition, thermal conductivity tests were also carried out on a mixture containing 50% by weight of expanded pearlites CR615 and 50% by weight of hydrophobic fumed silicas AEROSIL R974 and having an apparent density MV _mel of 85 kg/m ³ .

The thermal conductivity of the mixture was measured as a function of pressure and temperature before and after immersion in liquefied natural gas. The table below shows the thermal conductivity (in mW/(m∙K)) of the mixture.

T (°C) one ten 100 980 Before the dive 20 7 fourteen 24 34 -80 24 -160 4 eight 12 fourteen After the dive 20 eleven 22 29 36 -80 25 -160 7 eleven fourteen sixteen

In addition, in accordance with one embodiment, the powdered insulating material additionally contained a weight fraction z% of the ICI absorber and/or other possible additive(s), with z < 10% by weight of the mixture.

The IKI absorber was an IKI absorber selected from carbon black, graphite, silicon carbide, titanium oxides, and mixtures thereof.

In accordance with one embodiment, the average particle size of the ICI absorber was less than 25 microns, and preferably in the range from 3 microns to 20 microns.

When using the IKI absorber in an insulating filler, it is useful to determine the stable apparent density ϕ _axz of the part of the mixture consisting of the powdered insulating material and the IKI absorber. In particular, the stable apparent density ϕ _axz can be determined using the method described above for determining the stable apparent density ϕ _ax of a single insulating material.

Similarly, it is also useful to determine the stable apparent density ϕ _exz after densification of a portion of the mixture consisting of powdered insulating material and absorber. In particular, the stable apparent density ϕ _exz after compaction can be determined using the method described above for determining the stable apparent density ϕ _exz after compaction of one insulating material.

In addition, the apparent density MV _mel of the mixture must be greater than or equal to ϕ _ay * ϕ _axz /(y * ϕ _axz + (1 - y) * ϕ _ay ) and ϕ _exz /[1 - y * (1 - ϕ _exz / ϕ _vy )] to achieve a slight compaction of the insulating filler after immersion in the wetting liquid or its absence.

Example 7

A mixture of hydrophobic hydrogenated silica was prepared with an IKI absorber consisting of graphite.

The table below shows the characteristics of the resulting mixture.

Nature Name Particle size (µm) Stable apparent density ϕ _ex after compaction (kg/m ³ ) Stable apparent density ϕ _ax for LN ₂ (kg/m ³ ) Stable true density ϕ _vx for LN ₂ (kg/m ³ ) Hydrophobic fumed silica, with scavenger AEROSIL R974 (95% by weight) and graphite (5% by weight) <300 55 121 183

The table below shows the results obtained for a powdered insulating filler containing 25% by weight of perlite CR615 and 75% by weight of the mixture described above.

CR615 (y% by mass) AEROSIL R974 - graphite (95/5% by weight) (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Height change in %* Apparent density MV _mel of the mixture (kg/m ³ ) after immersion φ _ay * φ _ax / (y * φ _ax + (1 - y) * φ _ay ) in (kg / m ³ ) 25 75 201.7 95.17 198 -1.8 96.9 94.7

Example 8

Prepared two mixtures of granular airgel P400 and hydrophobic pyrogenic silica AEROSIL R974, having different mass fractions and/or apparent density MV _mel . The two mixtures were then completely immersed in liquid nitrogen, followed by a liquid nitrogen evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained.

Mixture Airgel P400 (y% by mass) AEROSIL R974 (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Height change in % Apparent density MV _mel of the mixture (kg/m ³ ) after immersion φ _ay * φ _ax / (y * φ _ax + (1 - y) * φ _ay ) in (kg / m ³ ) one 25 75 201.8 96.3 193.9 -3.9 100.2 105.9 2 25 75 198 106.7 201.1 +1.6 201.1 105.9

The tests made it possible to confirm, within the measurement accuracy, the lower limit of the apparent density MV _mel of a stable mixture after immersion in liquid nitrogen.

The stability range as well as the test results are shown in FIG. 8, in which the weight fraction of AEROSIL R974 is shown on the abscissa. For each of these examples, the apparent density MV _mel of the mixture (kg/m ³ ) before immersion is indicated by a triangle, while the apparent density MV _mel of the mixture (kg/m ³ ) after immersion is indicated by a square. The stability range of the mixture when immersed in liquid nitrogen is shaded.

Example 9

Two mixtures were prepared from expanded perlites CR615 and composition A, consisting of 75% by weight of hydrophobic fumed silica AEROSIL R974 and 25% by weight of silica airgel P100, crushed to a particle size of less than 100 μm and having different mass fractions and/or apparent densities of MV _mel .

The two mixtures were then completely immersed in liquefied natural gas, followed by an liquefied natural gas evaporation step. Height changes were measured, corresponding to a possible compaction effect, as well as the apparent density MV _mel of the mixture before and after immersion.

The table below shows the results obtained.

Mixture Perlite CR615 (y% by mass) Composition A (x% by weight) Mix height (before immersion) Apparent density MV _mel of the mixture (kg/m ³ ) before immersion Mix height (after immersion) Height change in % Apparent density MV _mel of the mixture (kg/m ³ ) after immersion φ _ay * φ _ax / (y * φ _ax + 1 - y) * φ _ay ) in (kg / m ³ ) one 25 75 196.3 101.1 181.9 -7.3 109.1 115.8 2 25 75 194.5 117.4 194.1 -0.3 117.7 115.8

The tests allowed to confirm, within the limits of measurement accuracy, the lower limit of the apparent density MV _mel of a stable mixture after immersion in liquefied natural gas.

The stability range as well as the test results are shown in FIG. 10, in which the weight fraction of composition A is shown on the abscissa. The range of mixture stability when immersed in liquefied natural gas is shaded.

The pressurized and insulated tank technologies described above can be applied to various types of tanks, such as an LNG storage tank in an onshore facility or floating structures such as a methane tanker or the like.

Let us turn to Fig. 9, a simplified view of a methane tanker 70 illustrates a sealed and insulated tank 71 in a generally prismatic shape mounted in a double hull 72 of the tanker. The tank wall 71 includes a main pressure barrier for contact with the LNG contained in the tank, an auxiliary pressure barrier located between the main pressure barrier and the double tanker hull 72, and two heat-insulating barriers located respectively between the main pressure barrier and the auxiliary pressure barrier and between auxiliary pressure barrier and double housing 72.

As is known, loading/unloading lines 73 located on the upper deck of a tanker can be connected via appropriate connectors to a sea or port terminal for transferring LNG to or from tank 71.

Fig. 9 illustrates an example of an offshore terminal comprising a loading and unloading station 75, a subsea pipeline 76, and an onshore facility 77. The loading and unloading station 75 is a fixed offshore facility comprising a movable boom 74 and a tower 78 that supports the movable boom 74. The movable boom 74 holds a bunch of flexible insulated pipes 79, which can be connected to the pipelines 73 loading/unloading. The movable boom 74, which can be adjusted, can be adapted to methane tankers of all sizes. Inside the tower 78 is a connecting pipeline, which is not shown. Station 75 loading and unloading allows loading and unloading of the methane tanker 70 from the onshore facilities 77 or on it. The latter contains tanks 80 for storing liquefied gas and connecting pipelines 81 connected by an underwater pipeline 76 to the loading and unloading station 75. The subsea pipeline 76 can be used to transfer liquefied gas between the loading and unloading station 75 and the onshore facility 77 over a long distance, such as 5 km, which allows the methane tanker 70 to be stopped well offshore during loading and unloading operations.

Pumps installed on board the tanker 70 and/or pumps installed in the shore facility 77 and/or pumps installed at the loading and unloading station 75 can be used to create the pressure necessary for the transfer of liquefied gas.

Although the invention has been described with reference to several specific embodiments, it is obvious that it is not limited to them in any way and that it covers all technical equivalents of the described means, as well as combinations thereof, if they are within the scope of the invention.

The use of the verb "consist", "comprise" or "include" and derivative forms does not exclude the presence of elements or steps other than those specified in the claim.

In the claims, the reference numerals in parentheses should not be interpreted as limiting the claim.

Claims (52)

1. A method of manufacturing an insulating section for a sealed and thermally insulated reservoir for storing a wetting liquid, wherein the wetting liquid is selected from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid nitrogen, liquid air, liquid argon, liquid xenon, liquid neon and liquid hydrogen, and the insulating section contains at least one compartment, and said method comprises the steps of: preparing a powdered insulating material selected from fumed silicas, silica aerogels and mixtures thereof, wherein said powdered insulating material has: characteristic size g _x of particles; a stable true density ϕ _vx for the wetting liquid, which corresponds to the true density of said powdered insulating material having said characteristic particle size g _x after immersion in the wetting liquid; and a stable apparent density ϕ _ax for the wetting liquid, which corresponds to a threshold apparent density of said powdered insulating material, beyond which the powdered insulating material having a characteristic particle size g _x does not experience compaction after immersion in the wetting liquid; and a stable apparent density ϕ _ex after densification, which corresponds to the state of maximum densification of said powdered insulating material having said characteristic particle size g _x ; prepare a granular filler selected from perlites, hollow spheres, granules of a foamed polymer material, granular aerogels having an internal degree of porosity that does not decrease after immersion in a wetting liquid, and mixtures thereof, moreover, the granular filler has a characteristic size g _y of particles, a stable apparent density ϕ _ay after compaction, which corresponds to the state of maximum compaction of said granular filler having said characteristic particle size g _y and true density ϕ _vy ; at least powdered insulating material and granular filler are mixed, moreover, powdered insulating material is present in the mass fraction x, and granular filler is present in the mass fraction y, while x + y ≥ 90%, x ≥ 25% and y ≥ 5%; place the mixture in the compartment of the insulating section in a state of compaction, so that: the true density of the powdered insulating material in the mixture between the grains of the granular filler is less than the aforementioned stable true density ϕ _vx , the apparent density of the granular filler in the mixture is less than the stable apparent density ϕ _ay after compaction, and the apparent density MV _mel of the mixture is greater than or equal to ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 – y) * ϕ _ay ) and ϕ _ex /[1 – y * (1 – ϕ _ex /ϕ _vy )]. 2. A method for manufacturing an insulating section according to claim 1, wherein the powdered insulating material and the granular filler are homogeneously mixed by mechanical agitation. 3. An insulating section for a sealed and thermally insulated tank for storing a wetting liquid, the wetting liquid being selected from liquefied natural gas, liquefied petroleum gas, liquid methane, liquid ethane, liquid propane, liquid nitrogen, liquid air, liquid argon, liquid xenon , liquid neon and liquid hydrogen, moreover, the insulating section contains at least one compartment, and a powdered insulating filler placed in said compartment, and the insulating filler contains a mixture of at least: x% by weight of a powdered insulating material selected from fumed silicas, silica aerogels and mixtures thereof, wherein said powdered insulating material has: characteristic size g _x of particles, a stable true density ϕ _vx for the wetting liquid, which corresponds to the true density of said powdered insulating material having said characteristic particle size g _x after immersion in the wetting liquid, a stable apparent density ϕ _ax for the wetting liquid, which corresponds to a threshold apparent density of said powdered insulating material, beyond which the powdered insulating material having said characteristic particle size g _x does not experience compaction after immersion in the wetting liquid, and a stable apparent density ϕ _ex after compaction, which corresponds to the state of maximum compaction of said powdered insulating material having said characteristic particle size g _x ; y% by weight of a granular filler selected from perlites, hollow glass spheres, foamed polymer material granules, granular aerogels having an internal degree of porosity that does not decrease after immersion in a wetting liquid, and mixtures thereof, the granular filler having a characteristic particle size g _y , stable apparent density ϕ _ay after compaction, which corresponds to the state of maximum compaction of said granular filler having said characteristic particle size g _y , and true density ϕ _vy ; while x + y ≥ 90%, x ≥ 25% and y ≥ 5%; moreover, the true density of the powdered insulating material in the mixture between the grains of the granular filler is less than the stable true density ϕ _vx ; the apparent density of the granular filler in the mixture is less than the stable apparent density ϕ _ay after compaction, and the apparent density MV _mel of the mixture is greater than or equal to ϕ _ay * ϕ _ax /(y * ϕ _ax + (1 – y) * ϕ _ay ) and ϕ _ex /[1 – y * (1 – ϕ _ex /ϕ _vy )]. 4. Insulating section according to claim 3, wherein the apparent density of the mixture is less than 250 kg/m ³ , preferably in the range of 50 to 220 kg/m ³ , and more preferably in the range of 60 to 190 kg/m ³ . 5. Insulating section according to claim 3 or 4, in which the mixture has a thermal conductivity of less than 45 mW/(m∙K) at a temperature of 20°C and normal atmospheric pressure, preferably in the range from 25 to 35 mW/(m∙K) at temperature 20°C and normal atmospheric pressure. 6. Insulating section according to any one of paragraphs. 3-5, wherein the granular filler has an average particle size in the range of 10 µm to 5 mm, preferably in the range of 20 µm to 2 mm, and more preferably in the range of 25 µm to 1 mm. 7. Insulating section according to any one of paragraphs. 3-6, in which the granular filler has grains, the ratio of mass to external volume of which is less than 500 kg/m ³ , preferably less than 200 kg/m ³ , more preferably in the range from 30 to 150 kg/m ³ . 8. Insulating section according to any one of paragraphs. 3-7, in which the granular filler contains expanded perlite. 9. Insulating section according to any one of paragraphs. 3-7, in which the granular filler contains hollow spheres made of glass or polymeric material. 10. Insulating section according to any one of paragraphs. 3-9, in which the granular filler itself has a thermal conductivity of less than 100 mW/(m∙K) at a temperature of 20°C and normal atmospheric pressure. 11. Insulating section according to any one of paragraphs. 3-10, in which the powdered insulating material contains hydrophobic fumed silica. 12. Insulating section according to any one of paragraphs. 3-11, wherein the powdered insulating material has an average particle size of less than 300 µm, preferably less than 200 µm, and more preferably in the range of 2 to 100 µm. 13 Insulating section according to any one of paragraphs. 3-12, in which x ≥ 50%. 14. Insulating section according to any one of paragraphs. 3-13, in which y ≥ 5%, preferably y ≥ 10%, and more preferably y ≥ 15%. 15. Insulating section according to any one of paragraphs. 3-14, in which the insulating filler contains z% by weight of an infrared absorber, with z < 10%. 16. The insulating section according to claim 15, in which the insulating part of the mixture, consisting of a powdered insulating material and an infrared absorber, has: characteristic particle size g _xz ; a stable apparent density ϕ _axz , which corresponds to the threshold apparent density of said insulating part of the mixture, beyond which the said insulating part of the mixture, having a characteristic particle size g _xz , does not experience compaction after immersion in the wetting liquid, and a stable apparent density ϕ _exz after compaction, which corresponds to the state of maximum compaction of the insulating part of the mixture, consisting of powdered insulating material and powdered infrared absorber, having the mentioned characteristic particle size g _xz ; in which the apparent density MV _mel of the mixture is also greater than or equal to ϕ _ay * ϕ _axz /(y * ϕ _axz + (1 – y) * ϕ _ay ) and ϕ _exz /[1 – y * (1 – ϕ _exz / ϕ _vy )]. 17. Insulating section according to claim 15 or 16, wherein the infrared absorber is selected from carbon black, graphite, silicon carbide, titanium oxides and mixtures thereof. 18. Insulating section according to any one of paragraphs. 3-17, comprising a bottom panel, a cover panel, and walls extending between the bottom panel and the cover cladding panel and forming at least one compartment. 19. Insulating section according to any one of paragraphs. 3-18, in which the apparent density of the powdered insulating material in the mixture between the grains of the granular filler is less than the stable apparent density φ _ax of the powdered insulating material. 20. A sealed and heat-insulating tank containing at least one heat-insulating barrier and a sealing membrane designed for contact with the fluid contained in the tank, adjacent to the said heat-insulating barrier, in which the heat-insulating barrier contains a plurality of insulating sections according to any one of paragraphs. 3-19. 21. Tanker (70) for transporting a wetting liquid, containing a double hull (72) and a tank (71) according to claim 20, located in a double hull. 22. The method of loading or unloading a tanker (70) according to claim 21, in which the fluid is supplied through insulated pipelines (73, 79, 76, 81) from a floating or shore storage (77) to a tanker tank (71) or vice versa. 23. A wetting fluid transfer system comprising a tanker (70) according to claim 21, insulated pipelines (73, 79, 76, 81) arranged so as to connect a tank (71) installed in the tanker hull with floating or shore storage (77), and a pump for supplying a flow of wetting fluid through insulated pipelines from the floating or shore storage to the tanker tank or vice versa.

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