JP2017516030A - Forced diffusion treatment for insulating parts made from foamed synthetic foam - Google Patents

Abstract

A process for forced diffusion treatment of a thermal insulation part (40) made of foamed synthetic foam, during the release phase, heating the insulation part to a release temperature above ambient temperature, while simultaneously Exposing the insulating component to a gas atmosphere having a low partial pressure for a gas having a diffusion coefficient into the foamed synthetic foam of carbon and nitrogen molecules or higher, and foaming of nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules or higher in the insulating components Ending the release phase when the accumulated partial pressure of the gas having a diffusion coefficient into the synthetic foam is less than a predetermined threshold.

Description

  The present invention relates to the field of use of foamed synthetic foams for the manufacture of thermal insulation components, and more particularly to closed cell thermoplastic or thermoset foams.

  The closed cell porous material consists of a solid matrix in which a large number of bubbles having a size of greater or lesser are trapped. As matrix, various synthetic thermoplastic and thermosetting materials such as polyurethane (PU), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), polyetherimide, polyethylene (PE), polypropylene (PP ) Or polyimide. This list is not comprehensive.

In the synthesis process by foaming, a foaming agent is used. There are two main families of blowing agents: blowing agents obtained from chemical reactions known as chemical agents, and blowing agents obtained from liquid evaporation with increasing temperature or reduced pressure known as physical agents. In particular, it can be used depending on the matrix synthesis process. Some synthetic foams can contain only physical agents (eg pentane foamed polypropylene foam), others can contain only chemical agents (eg PU foam foamed with carbon dioxide (CO ₂ )), and others The foam can use both types of foaming agents (eg, polyurethane foam foamed with several reagents including pentane and foaming gases 141b, 365 and 245fa). In all cases, the blowing agent is a foaming gas or produces a foaming gas that grows the foam cells and occupies the foam cells.

  The foaming gas is generally selected not only according to the processing characteristics and price of the foaming gas, but also according to the thermal conductivity of the foaming gas. The foaming gas is generally selected to exhibit a low diffusion coefficient into the selected matrix while limiting as much as possible the transfer of heat by conduction in the gas phase of the insulating material.

  Once the foamed foam part has been manufactured, these cells contain a starting gas or starting gas mixture. Throughout the lifetime of the foam under consideration, the cell is a diffusion phenomenon site that gradually changes the composition of the gas phase in the cell of the foam, especially the partial pressure of the foaming gas and the surrounding gas. . Thus, chemicals whose partial pressure is weaker in the surrounding medium than the foam tend to escape from the foam, whereas chemicals whose partial pressure is weaker in the foam than the surrounding medium tend to penetrate the foam by diffusion. .

  Thus, under storage conditions in open air, most of the blowing agent tends to leave the foam while air nitrogen and oxygen tend to diffuse inside the insulating material. Thus, if the foaming gas generally exhibits a lower thermal conductivity than the surrounding medium gas, the insulation quality of the foam under consideration tends to degrade over time. These phenomena are described as the aging of the foam.

This point is illustrated in FIG. 1, which shows the exposure time to the ambient atmosphere expressed in days on the abscissa axis for two parts of a polyurethane foam foamed with CO ₂ having a density of 130 kg / m ^3. As a function of, the ordinate axis represents the change in thermal conductivity at 20 ° C. expressed in units of W / mK. Curve 1 and diamond relate to a part having a thickness of 25 mm. Curve 2 and square relate to a part having a thickness of 50 mm.

  One idea underlying the present invention is to prevent and / or overcome the aging phenomenon of the foam described above.

To this end, according to one embodiment, the present invention provides a process for forced diffusion treatment of thermal insulation parts made of foamed synthetic foam comprising:
During the discharge phase, the insulating component is heated to a discharge temperature above ambient temperature and at the same time a low partial pressure for a gas having a diffusion coefficient into the foamed synthetic foam of at least nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules. Exposing insulating components to the gas atmosphere shown,
Ending the release step when the accumulated partial pressure of nitrogen molecules, oxygen molecules, carbon dioxide, and gases having a diffusion coefficient to the foamed synthetic foam of the nitrogen component or higher in the insulating component is less than a predetermined threshold.

  In other words, during the release phase, the insulating components will have these partial pressures in air at a standard pressure of nitrogen molecules, oxygen molecules, carbon dioxide and gases having a diffusion coefficient to the foamed synthetic foam above the nitrogen molecules. It is exposed to a gas atmosphere lower than the partial pressure of the substance.

  In addition, if the accumulated partial pressure of a gas having a diffusion coefficient into the foamed synthetic foam of nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules in the insulating component is less than a predetermined threshold, it is related to this accumulated partial pressure. The discharge phase is terminated when the physical properties of the insulating component reach a predetermined threshold or after a predetermined time.

  Further, the heat insulating component is disposed on the leak-proof heat insulating container wall to form an insulating barrier for the container wall. As a result, all or part of the container wall is heated during the discharge phase.

  Such a release step can release gases that are detrimental to the thermal properties of the foam, particularly nitrogen molecules, oxygen molecules, carbon dioxide, helium, hydrogen molecules, argon and the like.

According to one embodiment, the present invention also provides a process for forced diffusion treatment of thermal insulation parts made of foamed synthetic thermoset polyurethane foam containing at least 80% closed cells, the process comprising: Includes:
During the release phase, the insulation component is heated to a release temperature above ambient temperature, while at the same time the partial pressure for the gas with diffusion coefficient into the foamed synthetic foam of nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules is standard. Subjecting insulating parts to a gas atmosphere lower than their partial pressure in air at pressure, of nitrogen molecules, oxygen molecules, carbon dioxide in the insulating parts and gases having a diffusion coefficient to the foamed synthetic foam above the nitrogen molecules Ending the discharge phase if the accumulated partial pressure is below a predetermined threshold, or if the physical properties of the insulation component associated with this accumulated partial pressure reach a predetermined threshold, or after a predetermined time.

  According to one embodiment, the present invention also provides a leak-proof insulated container intended to contain liquefied fuel gas at a low temperature, the container wall comprising a multilayer structure adapted to the carrier wall, The multilayer structure includes a primary leak-proof membrane that contacts the liquefied fuel gas present in the container, and a secondary leak-proof membrane disposed between the primary leak-proof membrane and the carrier wall. A primary insulating barrier disposed between the secondary leakage barrier film and a secondary insulating barrier disposed between the secondary leakage barrier film and the carrier wall, wherein one or each thermal barrier is Includes thermal insulation parts made from foamed synthetic foam.

According to one embodiment, the container comprises a forced diffusion treatment device comprising:
A heating device capable of heating the primary leak-proof membrane and / or the carrier wall and / or the insulation barrier, for example to increase the temperature of the insulation component, for example by circulation of hot gas,
A pump drive device connected to each insulation barrier or insulation barrier comprising insulation components made from foamed synthetic foam and capable of reducing the total pressure of the gas phase in each insulation barrier or insulation barrier to less than standard pressure, preferably less than 10 mbar;
And control units that can:
Heating the insulation component to a discharge temperature higher than ambient temperature while controlling the heating and pump drive devices to expose the insulation component to a total pressure lower than the standard pressure during the discharge phase, and nitrogen molecules in the insulation component The release phase can be terminated if the accumulated partial pressure of the gas having a diffusion coefficient into the foamed synthetic foam of oxygen molecules, carbon dioxide and nitrogen molecules or more is below a predetermined threshold.

  BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more fully understood and other objects, details, features and advantages of the present invention will become apparent from the following description of some specific embodiments of the present invention given by way of example only and not limitation, with reference to the accompanying drawings, in which: During the explanation, it becomes clearer more clearly.

Figure 6 is a graph of the change in thermal conductivity of a foamed synthetic foam as a function of time exposed to the ambient atmosphere. It is a graph similar to FIG. 1 which shows the influence of the aged temperature of a foam synthetic foam. FIG. 2 is a cross-sectional view of a leak-proof insulating container in which a process according to the present invention can be performed. It is a side view of the insulation panel which can be used for the container of FIG. FIG. 2 is a cut-away view of a liquid natural gas tanker container and a terminal for loading / unloading the container.

  In the specification and claims, the term “standard pressure” is used synonymously with atmospheric pressure.

  We now describe a process for treating insulating parts made of synthetic foam that can prevent or overcome foam aging, and in fact can further improve the insulation quality of the insulating parts.

  To this end, during the first phase, known as the emission phase, the treatment process comprises the steps of heating the insulating component to a higher emission temperature than the ambient temperature and at the same time a gas atmosphere exhibiting a low partial pressure for nitrogen and oxygen molecules, That is, it comprises a step of exposing the insulating components to a gas atmosphere lower than their partial pressure in air at atmospheric pressure.

  This stage can accelerate the diffusion of the gas present in the foam towards the surrounding medium. The foam is placed under high temperature conditions in order to increase the diffusion coefficient of the gas present in the matrix. Furthermore, the foam is placed at least under reduced pressure for the main gas constituting the air in order to accelerate the diffusion of the gas present in the foam, at least nitrogen and oxygen molecules, towards the external gas atmosphere.

  This process is applicable to a wide variety of foamed synthetic foams and blowing agents. Preferably the foamed synthetic foam comprises at least 80% closed cells. The matrix material and blowing agent can be selected from the polymers and reagents described in the introduction. By way of example, the foamed synthetic foam is in particular a thermosetting polyurethane foam containing at least 80% closed cells.

  The release temperature is selected so as not to damage the foamed synthetic foam. For this reason, a release temperature of preferably less than 100 ° C. is selected.

  Temperatures up to 100 ° C. can be acceptable for certain polymers, such as polypropylene or polyethylene. For many synthetic polymers, the release temperature is preferably below 80 ° C. This threshold of 80 ° C. is preferred, for example, for polyurethane foam, PVC foam or polystyrene foam (especially to prevent sublimation of polystyrene). The choice of emission temperature may also take into account the heat resistance of other materials assembled with the insulating component according to the characteristics of the target application.

  An increase in temperature tends to increase the diffusion coefficient of the gas. Judging from the effectiveness, the release temperature preferably corresponds to a substantial increase in temperature. According to one embodiment, the discharge temperature is above 50 ° C and even above 60 ° C.

  The insulating component can be heated by various heating means such as radiation, conduction, eg in contact with hot solids, or conduction / convection, ie in contact with hot fluids.

  According to one embodiment, the gas atmosphere in the discharge phase further exhibits a low partial pressure for the foaming gas used in the production of the foamed synthetic foam. These features also allow the foam gas concentration during the discharge phase to be reduced in order to reduce the thermal conductivity of the foam.

  For the implementation of this release phase, the insulating foam is advantageously foamed with one or more blowing agents that exhibit the highest possible diffusion coefficient.

According to one embodiment, the foaming gas used for the production of foamed synthetic foam essentially comprises carbon dioxide. For example, rigid polyurethane foams can foamed by CO _2. The diffusion coefficient of CO ₂ is greater than the diffusion coefficient of other known blowing agents, particularly the foaming gases 141b, 245fa, 365, or pentane. Foam foamed with CO ₂ further exhibits the dual advantage of not using on the one hand a gas that tends to contribute strongly to global warming or ozone holes, and on the other hand the lowest manufacturing costs. This is because the foam foamed with CO ₂ is foamed by the chemical reaction of water.

For illustration, Table 1 shows the order of diffusion coefficient magnitudes measured at ambient temperature for various polyurethane foams having a density of 120-135 kg / m ³ .

  Table 2 shows the change in diffusion coefficient as a function of temperature, in particular the increase in diffusion coefficient with temperature.

  Several techniques can be used during the release phase to create a partial pressure gradient that allows the desired chemicals, particularly oxygen and nitrogen molecules and carbon dioxide, to be released from the foam.

  The first technique consists in subjecting the insulating component to a reduced total pressure. According to a corresponding embodiment, the gas atmosphere in the discharge phase exhibits a total pressure of less than standard pressure, preferably less than 10 mbar. This depressurization causes the external atmosphere to lose gaseous substances that tend to diffuse extensively into the foam. This reduced pressure can be established and maintained by a vacuum pump or other suction device. Suction allows the gas exiting the foam to be removed from the surrounding medium as it exits the foam. In this vacuum technique, the heating of the insulating parts is advantageously performed by direct conduction or radiation.

  A second technique as an alternative to the first technique consists of immersing the insulating component in an atmosphere that essentially contains one or more gases that are very difficult to diffuse into the foam. According to a corresponding embodiment, the gas atmosphere in the release phase is a gas phase of a gas having large molecules in forced convection, ie a gas phase showing a molar mass of 70 g / mol or more.

  The gas phase of a gas with large molecules also creates a partial pressure gradient that promotes the migration of nitrogen and oxygen molecules towards the outside of the insulating component as long as it exhibits a very low content of nitrogen and oxygen molecules. Further, convective movement allows the gas exiting the foam to be removed from the surrounding medium as the gas exits the foam.

Flushing with this gas, the diffusion coefficient is very low to form gas having a very large molecule, such as cyclopentane _{(C 5 H 10), CF} 4 gas, R-23 gas, R-508B gas, R -134 _(CH 2 FCF ₃₎ gas, 141b gas, 245fa gas can be performed using any other gas having 365 gas or 70 g / mol or more molar mass.

  The molar masses of several gases are shown in the following table, but the following gases exhibit a molar mass of 70 g / mol or higher and tend to be used as a gas atmosphere in which insulating components are immersed during the discharge phase.

  This is because it is observed that the diffusion phenomenon through the foam becomes faster as the molar mass of the gas decreases.

The discharge phase is terminated after the specific gas partial pressure initially present in the cell has reached the target value. The most important and most harmful gases for the conductivity of the foam are molecular nitrogen and molecular oxygen, possibly CO ₂ (for example when used as a blowing agent). Therefore, it is appropriate to end the release step when the accumulated partial pressure of at least nitrogen molecules and oxygen molecules in the insulating component is below a predetermined threshold.

  According to one embodiment, the predetermined threshold is not more than 30 mbar for the partial pressure of gas having a diffusion coefficient into the foamed synthetic foam of nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules or more. This threshold roughly corresponds to a foam containing 3% air.

  Such conditions can be detected by direct or indirect experimental measurements and / or calculations, in particular by numerical modeling. According to an embodiment corresponding to direct measurement, nitrogen and oxygen molecules are assayed in the insulating component during the release phase, and when the concentration of nitrogen and oxygen molecules measured in the insulating component crosses a desired threshold, Stop the release phase.

  According to an embodiment corresponding to indirect measurement, one or more physical properties related to the concentration of nitrogen and oxygen molecules in the insulating component, for example the thermal conductivity of the foam, are measured and the release phase is determined by the measured properties. Is otherwise determined experimentally or stopped when modeling reaches a value corresponding to the desired concentration.

  According to one embodiment, the release phase is a predetermined time determined by calculation, in particular by numerical modeling, taking into account the thermodynamic conditions of the treatment and the physical properties of the foam and the properties of the chemicals present. It will be stopped later.

  This forced diffusion process can be applied to any type of insulating component made from foamed foam. This forced diffusion treatment process can be carried out directly in a dedicated processing plant, for example in a factory for the production of insulating components, or in an environment where insulating components are used.

  According to one embodiment, the insulating component includes protrusions or holes with small dimensions, which increase the replacement surface area of the insulating component in a gas atmosphere. With these features, the foam parts exhibit a high volume / exchange surface area ratio to promote the diffusion phenomenon during the discharge phase. For this reason, the foam part has a carefully distributed groove, for example with a thickness on the order of millimeters, or a small diameter, for example about 2 mm, to promote gas diffusion without the risk of creating a gas convection zone Indicates a dent. These protrusions or holes can be arranged in particular in the width or length of the parallelepiped panel.

  According to one embodiment, the insulating component is placed on a leak-proof and insulated container wall to form an insulating barrier on the container wall. Insulating parts made of foamed foam can in particular form a component of a prefabricated insulating panel installed in the wall thickness of the container, for example in a liquid natural gas tanker. By way of example, it should be noted that an example of such a prefabricated panel is described in publication FR-A-2781557.

  According to a corresponding embodiment, the releasing step comprises heating all or part of the container wall. In the case of a container intended to contain a cooling product, for example a liquefied gas container, this heating of the container wall must be performed with the container empty. Such heating can be obtained by a number of means such as radioactive heating, conductive heating or conductive / convective heating. According to one embodiment, the inner and / or outer surface of the container wall is exposed to a hot gas atmosphere.

  According to a preferred embodiment, the process further comprises one or more diffusion inhibiting effects applied to the insulating component during the operation phase following the release phase, wherein this or each inhibiting effect is within the foam material component. It is effective in delaying the gas diffusion toward it. These features prevent or delay the entry or re-entry of ambient gas into the foam when used later after the release phase.

  Preferably, the diffusion-inhibiting action is an action that continues substantially over time to permanently prevent or retard air or other ambient gas permeation by diffusion into the synthetic foam. For this reason, different inhibitory actions can be used alternatively or in combination. Several inhibitory effects can be used in combination by being used simultaneously in time or by being used in succession in time during successive periods of the operating phase of the insulating component.

  Three embodiments of the inhibitory effect are shown below by way of illustration.

  According to a first embodiment, the inhibiting action consists in exposing the insulating component to a gas atmosphere, the total pressure being maintained below the standard pressure, preferably below 10 mbar. These features keep the foam in space at reduced pressure. Since in this case the ambient gases have a very low partial pressure, their very small diffusion no longer affects the conductivity of the foam.

  According to the second embodiment, the inhibiting action consists of maintaining the insulating component at a temperature below 0 ° C., preferably below −20 ° C. Due to these characteristics, the foam is maintained under cold conditions, where the diffusion coefficient of the ambient gas into the matrix is considerably lower than when it is during the release phase. Because the diffusion phenomenon is very small for this reason, the movement of ambient gas to the cell can be greatly delayed until the reaction rate is reached, and this effect is negligible during the use of insulation.

FIG. 2 shows the effect of low temperature on the change in thermal conductivity over time. The thermal conductivity expressed on the ordinate axis in W / mK is plotted as a function of aging expressed on the abscissa axis in days. The example relates to a PU foam having a density of 40 kg / m ³ . In curves 3 and 4, the thermal conductivity is measured at a positive temperature of + 20 ° C. In curves 5 and 6, the thermal conductivity is measured at a negative temperature of −120 ° C., which results in a considerably lower value.

In curves 3 and 5, foam aging was performed at a positive temperature of + 20 ° C. In curves 4 and 6, foam aging was performed at a negative temperature of -20 ° C. Thus, the cooling effect as a gas diffusion retarder is very significant over a period of at least 60 days. The aging of high density foams is from high initial thermal conductivity ranging from 0.024 W / mK for foams (this foaming gas is HFC and 141b) to 0.027 W / mK for foams foamed with CO _2. A similar observation starting is obtained.

  According to the third embodiment, the inhibitory action consists of exposing the insulating component to a gas atmosphere that essentially contains chemicals with large weak diffusing molecules. With these features, the foam is maintained in a non-diffusing gas environment.

It is preferred to select a gas that exhibits the following properties: very low diffusion coefficient of foam into the matrix, low thermal conductivity, and density and viscosity that greatly limit thermal convection. Gases that can be used for this purpose include CF ₄ , R-23 gas, R-508B gas, R-134 (CH ₂ FCF ₃ ) gas, 141b gas, 245fa gas, 365 gas, or a molar mass of 70 g / mol or more. Have any other gas. The selection from the gases described above can be made as a function of temperature and pressure conditions, particularly in the operating environment. This is because the gas selected is advantageously in the vapor phase under the temperature and pressure conditions of the operating environment. As a result, in order to maintain these materials in the vapor phase, a relatively low pressure is simultaneously maintained in the operating environment of the insulating component, for example, in the primary or secondary insulating barrier of the vessel wall for liquefied natural gas. It may be necessary. By way of example, a gas that is particularly suitable for the operating environment in the primary or secondary insulation barrier of the vessel wall for liquefied natural gas is gas HFCR-508-B, particularly at a temperature of about −100 ° C. to −120 ° C. HFCR-23 and CF ₄ at low temperature.

As an example, the saturated vapor pressure of HFCR23 gas is 60 mbar at −120 ° C. The saturated vapor pressure of CF ₄ gas at −160 ° C. is 30 mbar and 1.15 bar at −120 ° C.

  Embodiments of processes applied to foamed foam blocks that can be used in the manufacture of thermal barriers arranged in the wall thickness of the container for liquefied gas will now be described.

  According to the embodiment represented in FIG. 3, the leak-proof insulation container 10 intended to contain liquefied fuel gas at a low temperature exhibits a prismatic shape and has a carrier structure formed by a double hull of a tanker. Incorporated. The outer and inner walls of the double hull forming the carrier structure are designated by numerals 11 and 12 in FIG. A ballast space 13 is defined between the two walls 11 and 12.

  As illustrated in FIG. 3, the container wall includes a multilayer structure adapted to the carrier wall 12. The multilayer structure includes a primary leak-proof film 15 in contact with the liquefied fuel gas present in the container, a secondary leak-proof film 16 disposed between the primary leak-proof film 15 and the carrier wall 12, and the primary leak-proof film 15 and the second A primary thermal barrier 17 disposed between the secondary leak-proof membrane 16 and a secondary thermal barrier 18 disposed between the secondary leak-proof membrane 16 and the carrier wall 12 are included.

  There are a number of materials that can be used for the thermal barrier. In the embodiment under consideration, one or each thermal barrier 17 and 18 comprises a thermal insulation component made of foamed synthetic foam.

  In one embodiment, the construction form of the insulating block is processed after installation on the ship but in a period prior to cooling the tanker vessel. For this reason, the foam block is heated to a release temperature at which commonly used materials such as plywood, glass wool and triplex are not damaged by the heat, such as foam and any components used in combination with the foam. According to a preferred embodiment, this temperature varies between about 60-80 ° C. Therefore, the diffusion coefficient of the gas present in the foam is increased in order to shorten the duration of the forced diffusion process.

  For this reason, the internal space 20 of the container and possibly the ballast space 13 can be reheated to a desired temperature using the foaming equipment 21, for example, foaming hot air or exhaust gas recovered from the equipment for propelling the tanker. Other heating means can also be used. FIG. 3 illustrates, for this purpose, a foam pipe 22 exiting into the internal space 20 and a foam pipe 23 exiting into the ballast space 13.

  The insulating spaces 17 and 18 or one of them thus reheated are also placed at a reduced pressure, for example 0.1 mbar to 10 mbar, in order to increase the pressure gradient responsible for the diffusion of the gas present in the foam, ie Ensuring that the surrounding medium of the foam exhibits a sufficiently low partial pressure for the gas exiting the foam to substantially empty the cell of gas it contains. For this purpose, a vacuum pump 25 arranged to extract the gas phase from the primary insulation barrier 17 and / or the secondary insulation barrier 18 can be used. FIG. 3 illustrates a suction pipe 26 exiting into the primary space and a suction pipe 27 exiting into the secondary space for this purpose.

  Gas diffusion is forced by temperature and concentration gradients until satisfactory levels are obtained. This discharge phase is an electronic control unit 30 that controls the vacuum pump 25 and the foaming equipment 21 by the use of various feedback parameters 31, for example by physical measurements made in the vessel by pressure, temperature, gas analysis or other sensors. Can be guided automatically by.

  This release phase is preferably followed by a diffusion inhibiting action that can maintain the foam cells in a substantially depleted state of the gas that impairs thermal conductivity.

  One possibility of action is to maintain the gas in the insulating space at a reduced pressure throughout the operation of the tanker to reduce the partial pressure of the material that tends to move into the foam.

  One possibility of action is to cool the container so that the insulating foam is placed under cold conditions. Due to these reductions in temperature, the diffusion coefficient of the surrounding gas into the foam can be greatly reduced even when the insulating spaces 17 and 18 are returned to atmospheric pressure. Thus, each insulating space can be flushed with nitrogen vapor as long as the tanker vessel is under cooling conditions without the risk of compromising the thermal conductivity properties of the foam.

  One possibility of the action when the tanker returns to substantially ambient temperature conditions, i.e. when the container is empty, is not necessarily to heat the container wall at the same time, but by re-creating the vacuum with the vacuum pump 25. is there. This can prevent diffusion of ambient gas into the foam, and in some cases, empty the peripheral layer of the flushing gas foam that would have been able to diffuse in a reduced amount.

  Another possibility of action is to fill the insulating space with a gas that exhibits a diffusion coefficient into the matrix of the lowest possible foam.

  Applying a surface treatment that has a low diffusion coefficient of the gas to the external surface of the foam that is leak-proof to the gas or exposed to the surrounding gas, in order to improve the effect of the above-mentioned inhibition action You can also. Such a surface treatment is put in place before the foam block is installed on the container wall, for example, in a manufacturing plant where the foam block is subjected to forced diffusion treatment in advance. The surface treatment can then remain in place throughout the operational life of the insulating component.

  In particular, according to one embodiment shown in FIG. 4, the insulating component is a flat parallelepiped foam block 40 whose surface is parallel to the length and width direction of the block and the thickness direction of the block. Shows two main surfaces 43, 44 separated from each other and peripheral surfaces 41, 42 which are smaller than the main surfaces and extend along the thickness direction of the block between the two main surfaces. The leak-proof coating 45 now shows the form of a strip that is disposed longitudinally on the peripheral surfaces 41, 42 of the block throughout the block and exhibits a width less than the thickness of the block.

  According to the embodiment of FIG. 4, this leak-proof coating is only placed on the surface of the foam block 40, which is exposed to temperatures in excess of −20 ° C. during operation (ie close to the double hulls 11, 12). portion). For example, the width of the strip 45 is 3-6 cm for a secondary insulation barrier made from high density PU foam, ideally 4.5 cm.

  The hermetic coating can be produced in several ways. For example, the hermetic coating includes a layer of polymer resin and / or paint disposed on the outer surface of the insulating component and / or includes a metal sheet having a thickness of, for example, a few microns adhesively bonded to the outer surface of the insulating component. . Such metal sheets can be made from aluminum or other metals.

  In the embodiment of FIG. 4, the foam block 40 is used in a prefabricated insulating panel 50, this structure is otherwise known and is shown again here.

  Panel 50 has a substantially parallelepiped rectangular shape; it forms a first sheet 51 of plywood or composite material having a thickness of 9 mm, a foam block 40 thereon, and a secondary membrane 16 thereon. A leak-proof composite material layer 52 intended to do so. The second foam block 53 is arranged on the leak-proof layer 52 and this foam block itself holds a second sheet of plywood 54 having a thickness of 12 mm. The subassemblies 53, 54 are intended to constitute elements of the primary insulation barrier 17. When viewed in a plane, it is rectangular in shape and this side is parallel to the subassemblies 51, 40, 52. The two subassemblies have two rectangular shapes with the same center when viewed in plane. A constant width peripheral rim 57 exists throughout the subassemblies 53, 54 and includes the edges of the subassemblies 51, 40, 52. The leak-proof layer 52 is made, for example, from a multilayer composite that includes one or more metal sheets and one or more glass fiber mats impregnated with a polymer resin.

  The techniques described above for preventing the aging of insulating components can be used in different types of tanks, such as LNG tanks, on land facilities or floating structures, such as liquid natural gas tankers.

  A vessel with a forced diffusion treatment device as shown in FIG. 3 can also be manufactured, for example, in the form of a terrestrial storage facility for storing LNG, or in a coastal or deep-sea floating structure, especially a liquid natural gas tanker, floating body It can be installed in a storage regasification unit (FSRU), floating production storage and shipping (FPSO), etc.

  According to one embodiment, a tanker for the transport of a chilled liquid product comprises a double hull and a container as described above arranged in the double hull.

  According to one embodiment, the present invention also provides a process for loading or unloading such tankers, where the cooling liquid product is from a floating or onshore storage facility to a tanker container or tanker container. It is transported through an insulation pipe from to this equipment.

  According to one embodiment, the present invention also provides a mobile system for a chilled liquid product, which system can be used for a tanker, a container installed in a tanker hull as described above, to a floating or onshore storage facility. Insulating pipes arranged for connection and a pump for drawing a stream of cooling liquid product through the insulating pipes from a floating or onshore storage facility to the tanker vessel or from the tanker vessel to the facility.

  Referring to FIG. 5, a cut-away view of a liquid natural gas tanker 70 shows a leak-proof insulating container 71 having a general prismatic shape adapted to a double hull 72 of the tanker. The wall of the vessel 71 has a primary leakage barrier intended to contact the LNG present in the vessel, a secondary leakage barrier arranged between the primary leakage barrier and the tanker double hull 72, and the primary It includes two insulating barriers arranged respectively between the leakage barrier and the secondary leakage barrier and between the secondary leakage barrier and the double hull 72.

  In a manner known per se, the load / unload pipe 73 located on the main deck of the tanker can be connected by a suitable connector to the coastal or hull terminal in order to move the LNG cargo to or from the container 71.

  FIG. 5 represents an example of a coastal terminal that includes a loading and unloading station 75, a groundwater pipeline 76 and a ground facility 77. The loading and unloading station 75 is an offshore facility that includes an adjustable movable arm 74 and a tower 78 that supports the movable arm 74. The movable arm 74 holds a bundle of insulating hoses 79 that can be connected to the load and unload pipe 73. Adjustable movable arm 74 is adjusted to the dimensions of all liquid natural gas tankers. A connecting pipeline (not shown) extends inside the tower 78. The loading and unloading station 75 enables the loading and unloading of the liquid natural gas tanker 70 from or to the ground facility 77. This facility includes a connecting pipeline 81 connected to a loading and unloading station 75 via a liquefied gas storage tank 80 and a groundwater pipeline 76. The groundwater pipeline 76 allows liquefied gas to move between the loading and unloading station 75 and the ground facility 77 over a considerable distance, for example 5 km, which is a significant amount from the coast during loading and unloading operations. The liquid natural gas tanker 70 can be maintained at a short distance.

  In order to generate the pressure required for the movement of the liquefied gas, a pump with a tanker 70 and / or a ground facility 77 and / or a pump with a loading and unloading station 75 is used.

  Although the invention has been described in connection with some specific embodiments, the invention is in no way limited thereto, but includes the technical equivalents of the means described, and all combinations thereof (the latter being It is very clear if it is within the context of the present invention.

  The use of the verb “to comprise” or “to include” and its synonymous forms does not exclude the presence of elements or steps other than those stated in a claim. The use of the indefinite article “a” or “an” for an element or stage does not exclude the presence of a plurality of such elements or stages unless specifically stated otherwise.

  In the claims, any reference signs placed between parentheses shall not be construed as limitations on the claim.

Claims (19)

A process for forced diffusion treatment of a thermal insulation component (40) made of foamed synthetic foam disposed on a leak-proof thermal insulation container wall and forming an insulation barrier of said container wall, comprising:
During the discharge phase, all or part of the container wall is heated to heat the insulating component to a discharge temperature that exceeds ambient temperature, while at the same time the nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules or more Exposing the insulating component to a gas atmosphere exhibiting a low partial pressure for a gas having a diffusion coefficient into the foamed synthetic foam, wherein the low partial pressure is in air at standard pressure for each of these materials A process lower than the partial pressure of
When the accumulated partial pressure of a gas having a diffusion coefficient into the foamed synthetic foam of nitrogen molecules, oxygen molecules, carbon dioxide and nitrogen molecules in the insulating component is less than a predetermined threshold, or the insulation relating to the accumulated partial pressure Ending the release phase when the physical properties of the part reach a predetermined threshold, or after a predetermined time;
Including processes.   The process of claim 1, wherein the foamed synthetic foam comprises at least 80% closed cells.   The process according to claim 1 or 2, wherein the foamed synthetic foam is a polyurethane foam.   The process according to claim 3, wherein the polyurethane foam is a thermosetting foam.   The process according to any one of claims 1 to 4, wherein the discharge temperature is less than 100 ° C, preferably less than 80 ° C.   The process according to any one of claims 1 to 5, wherein the discharge temperature is above 50 ° C.   The process according to any one of the preceding claims, wherein the foaming gas used for the production of the foamed synthetic foam essentially comprises carbon dioxide.   8. Process according to any one of the preceding claims, wherein the gas atmosphere of the discharge stage exhibits a total pressure of less than standard pressure, preferably less than 10 hPa (10 mbar).   The process according to any one of claims 1 to 8, wherein the gas atmosphere of the releasing stage is a gas phase of a gas exhibiting a molar mass of 70 g / mol or more during forced convection.   The predetermined threshold value is 30 hPa or less with respect to an accumulated partial pressure of a gas having a diffusion coefficient of nitrogen molecules, oxygen molecules, carbon dioxide, and nitrogen molecules to the foamed synthetic foam. The process described in   11. A process according to any one of the preceding claims, wherein the insulating component comprises protrusions or holes with small dimensions, which increase the replacement surface area of the insulating component in the gas atmosphere.   The method further comprises a diffusion inhibiting effect applied to the insulating component during an operation phase following the release phase, wherein the inhibition effect is effective to delay gas diffusion toward the interior of the foam material. The process according to any one of 11 to 11.   13. Process according to claim 12, wherein the inhibiting action consists of exposing the insulating component to a gas atmosphere, the total pressure of the gas atmosphere being maintained below a standard pressure, preferably below 10 hPa.   The process according to claim 12 or 13, wherein the inhibitory action comprises exposing the insulating component to a gas atmosphere essentially containing a chemical substance having a molecular weight of 70 g / mol or more.   15. Process according to any one of claims 12 to 14, wherein the inhibitory action consists of maintaining the insulating component at a temperature below 0 ° C, preferably below -20 ° C.   The process according to any one of the preceding claims, wherein the insulating component comprises a hermetic coating (45) disposed on an outer surface of the insulating component.   The process of claim 16, wherein the hermetic coating comprises a layer of polymer resin and / or metal sheet disposed on an outer surface of the insulating component.   The insulating component is a flat parallelepiped foam block (40), and the surface is parallel to the length and width direction of the block and is separated from each other in the thickness direction of the block. A surface (43, 44) and a peripheral surface (41, 42) smaller than the major surface extending along the thickness direction of the block between the two major surfaces, wherein the leak-proof coating is 18. Process according to claim 16 or 17, showing the form of a strip (45) arranged longitudinally on the peripheral surface (41, 42) of the block throughout the block and showing a width less than the thickness of the block. . A leak-insulated insulation container (71) intended to contain liquefied fuel gas at a low temperature,
Here, the wall of the container includes a multilayer structure adapted to the carrier wall (12), the multilayer structure being in contact with the liquefied fuel gas present in the container, the primary leak-proof membrane (15), the primary leak A secondary leak-proof membrane (16) disposed between the stop membrane and the carrier wall, a primary thermal barrier (17) disposed between the primary leak-proof membrane and the secondary leak-proof membrane, and the A secondary insulation barrier (18) disposed between a secondary leak-proof membrane and the carrier wall, wherein one or each insulation barrier comprises an insulation component made from foamed synthetic foam;
The container comprises a forced diffusion treatment device;
The forced diffusion processing device is
A heating device (21, 22, 23) capable of heating the primary leak-proof membrane and / or the carrier wall and / or the thermal barrier to increase the temperature of the thermal insulation component;
Connected to the thermal barrier or each of the thermal barriers including the thermal insulation component made from the foamed synthetic foam, the total pressure of the gas phase in each of the thermal barrier or thermal barrier can be reduced to less than standard pressure, preferably less than 10 hPa. A pump drive device (25, 26, 27);
A control unit (30),
The control unit is
Heating the insulation component to a discharge temperature higher than ambient temperature, and simultaneously controlling the heating device and the pump drive device to expose the insulation component to a total pressure lower than a standard pressure during the discharge phase; and the insulation The release step can be terminated when the accumulated partial pressure of nitrogen molecules, oxygen molecules, carbon dioxide, and gases having a diffusion coefficient in the foamed synthetic foam equal to or higher than nitrogen molecules in the part is less than a predetermined threshold value. A container characterized by.

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