JP2015525860A - Insulating panel manufacturing method - Google Patents

Abstract

The present invention relates to a method for producing a heat insulation unit (1) having a long service life at a cryogenic temperature by a unit comprising a heat insulation board (8) and a liquefied natural gas storage tank (10). The method comprises at least two foils (2, 3) arranged in each layer in the laminating direction and at least one spacer (4). The following steps constitute the manufacturing method of the unit: forming an opening with at least one pocket (6) in the jacket while ultrasonically welding along the boundary (5) of the foils laminated layer by layer And the at least one spacer inserted into at least one of the at least one pocket has at least one outer volume of the at least one spacer smaller than an inner volume of the at least one pocket, After degassing (exhausting) the pocket in which the spacer is inserted, the pocket in which at least one spacer is inserted is sealed by ultrasonic welding.

Description

  The present invention relates to a method for manufacturing a thermal insulation unit (board / panel) having a long service life, and particularly to ultra-low thermal conductance properties for use in applications such as cryogenic transport and storage. ) Insulation boards / panels comprising part of the vacuum insulation units.

  Vacuum insulation is an advanced insulation technique that is significantly superior to common materials. In general, vacuum insulation is 3 to 7 times better than typical polyurethane foam, polystyrene foam and fiberglass matting. A vacuum insulation panel (VIP) is the most common embodiment of vacuum insulation. Usually, these panels are flat, but when a vacuum is maintained, they can be formed into a shaped structure and can be resistant to heat conduction (heat resistance). The pressure levels within these VIPs are often in the range of 25 kPa (ie, 0.25 bar) or less.

  In order to maintain the correct insulation value during the life span of the entire VIP, the panels are kept fluid / vapor tight and these absolute requirements have traditionally been The minimum wall thickness is set (see Patent Document 1). On the other hand, in many applications where thermal insulation is required, it is advantageous to make the thermal insulation thickness as small as possible, for example, to avoid space limitations.

The importance of maintaining low thermal conductance in the field of transporting fluid gases on ships is particularly recognized. In this particular application, companies can achieve significantly lower costs when the average boil-off rates are reduced. For example, it is not uncommon for the boil-off rate in a typical storage tank during transportation of liquefied natural gas (LNG) to be 0.15% (BOR / day). That is, if a tank were stored LNG initial 150,000 ³ is about 4,220M ³ in flight 20 days lost (volatile), the LNG costs were assumed to be 370 US dollars / ^{m 3,} about 1 This will result in an economic loss of .56 million dollars. However, if the BOR (boil-off rate) is reduced by, for example, 0.06%, the economic loss corresponding to the same operation will be about $ 630,000, that is, an economy of over $ 930,000 in one operation Loss can be reduced. If estimated to ship 160 days a year, companies have the potential to save about $ 7.5 million per ship. Even if it is reduced by 0.05%, that is, from 0.15% to 0.1%, it is possible to reduce the amount by about 4.1 million dollars. It is most important for companies to improve insulation, that is, to store and transport liquid gas at cryogenic temperatures.

  High-frequency welding (ultrasonic welding) is a method in which high-frequency ultrasonic acoustic vibrations are locally applied to a work piece that has been brought into close contact with pressure. It is an industrial technology that produces welds in a solid state. The advantage of ultrasonic welding is that it is not necessary to fix the component to the jig for a long time until the joint dries or hardens, and it can be performed at a higher speed than general adhesives and dissolving agents. Welding is easy to automate and can be cleanly and precisely joined; the weld location is clean and does not require much touch-up work. In addition, since the heat influence on the material is low, it is possible to weld many materials at the same time.

  The use of thin film ultrasonic welding is known in the field of manufacturing VIPs. For example, Patent Document 2 particularly discloses a vacuum heat insulating material that is provided with a core so that three sides of two aluminum foils are inserted into an ultrasonically welded pocket, and then sealed with deaeration (exhaust). The manufacturing method is disclosed. However, the manufactured panels are only suitable for the insulation of fluids having a temperature above room temperature. In addition, these VIPs have a somewhat complex configuration with multiple layers.

  In addition, a method of manufacturing a VIP suitable for heat insulation of a refrigerator by using heat welding is known. For example, Patent Document 3 discloses a vacuum heat insulation panel for applying to a refrigerator that deaerates and seals after inserting a core material inside a pocket (inner bag) formed by heat welding three sides. A manufacturing method is disclosed. The disclosed document does not employ ultrasonic welding, and the completed VIP has a somewhat complicated structure with multiple layers. The use of ultrasonic welding has a lower thermal effect on the material than, for example, thermal welding, so that more materials can be joined.

European Patent EP 0 857 833 A1 JP 2006-118638 A European Patent EP1647759A2

  Accordingly, the present invention solves the above-mentioned problems of the method for manufacturing a heat insulation unit, that is, a simple vacuum insulation that is a building block for a heat insulation board having ultra-low thermal conductance characteristics even at a very low temperature. It aims at providing the manufacturing method of a unit.

  The above-mentioned problems are a method of manufacturing a heat insulating unit having a long service life as shown in claim 1, a heat insulating board as shown in claim 10, and a storage of LNG, LPG or LEG as shown in claim 16. This is achieved by a liquefied gas storage tank. Further advantages are defined in the dependent claims.

In particular, the present invention discloses a method for manufacturing a heat insulation unit having a long service life at a cryogenic temperature. The method includes the following steps;
-Placing a second layer of at least one foil on the first layer of at least one foil in a layered relationship, layer by layer;
-Ultrasonically welding and joining the first layer of at least one foil and the second layer of at least one foil to form an opening in the jacket having at least one pocket;
-At least one spacer is inserted into at least one of the at least one pocket, the total outer volume of the at least one spacer being smaller than the inner volume of the at least one pocket;
-Degassing (exhausting) the pocket with at least one spacer inserted;
Sealing the pocket with at least one spacer inserted by ultrasonic welding.

  It is preferable that ultrasonic welding is performed along the boundary (side edge) of the foil laminated | stacked for every layer. In addition, with respect to the distance (L, W) of all the units, the boundary of the heat insulating unit is defined as a region of 20% extending from each end to the end lying on the opposite side. It is preferably up to 10% of the unit distance (L, W).

  It is preferable that at least a part of the ultrasonic welding is performed along at least two parallel or substantially parallel paths, whereby a plurality of weldings can be performed. Such a plurality of weldings can increase the service life of the vacuum heat insulating material and ensure high mechanical stability. At least one of the at least one evacuated pocket is preferably subjected to an internal pressure of 25 kPa (ie 0.25 bar) or less, more preferably 10 kPa (ie 0.1 bar) or less.

  The thermal conductance of the material increases in proportion to the area of the conductive material, so that ultra-low thermal conductivity is ensured in the edge zones where the hot and cold foils are joined. The thickness of the foil should be thin, preferably 1 mm or less, more preferably 500 micrometers or less, for example 100 micrometers. This is particularly important in highly adiabatic insulation systems where excessive heat transfer is allowed to a minimum. Furthermore, the thinner material is easier to join by ultrasonic welding.

  If the spacer composition material is properly selected, the overall thermal conductivity of each unit will be about 1 W / m · K or less, and will be able to withstand a pressure of at least 1 bar. More preferably, the overall thermal conductivity of each unit is, for example, a polyurethane foam, a polystyrene foam or a glass fiber mat, that is, a general thermal conductivity of about 0.02 W / m · K or less. Should be better than insulation. The spacer component can in principle be any material that meets the above requirements, i.e. it has a low thermal conductivity, e.g. capable of withstanding a certain pressure around 1 bar. For example, examples of the spacer material include one or more materials selected from the group of ceramic fiber, cork, polystyrene, fiber glass, pearlite, low density polymer, polyurethane, rice husk, airgel, and wood.

  The present invention also includes a thermal insulation board for placement on a wall of a fluid storage container that stores a fluid having an average fluid temperature different from the ambient temperature outside the fluid storage container, the board disclosed at least above. Obtaining at least one unit by a manufactured method. The board may comprise a plurality of thermal insulation units mounted in at least a two-dimensional matrix shape on the outer and / or inner walls of the fluid storage container. A preferred embodiment of a thermal insulation board composed of two or more two-dimensional thermal insulation unit layers is, for example, in the case of three layers, with one or more adjacent layers in the lateral position of one layer May be shifted. The average fluid temperature may be equal to or lower than the temperature around the tank, for example, between 0K and 200K.

  The heat insulation board described above is a tank or refrigerator for storing a cryogenic liquid such as liquid helium, liquid hydrogen, liquid nitrogen, liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquefied ethylene gas (LEG) or the like. It can be used for any application that requires heat insulation, such as various home appliances such as refrigerators and freezers. Furthermore, the heat insulation board of the present invention can insulate both the stored liquid and direct or indirect contact. An example of liquid hydrogen storage using vacuum insulation boards / panels is the temporary storage or use of energy from the production of surplus electricity for temporary storage or for use in the event of a temporary shortage of energy. There is a reliable source of hydrogen for dependent equipment.

  In the following description, a number of specific descriptions are introduced to provide embodiments of the method and apparatus that can be fully understood. Those skilled in the art will be able to implement these embodiments without one or more specific descriptions or with other components, systems, etc. In other instances, well-known structures or operations are not disclosed or described in detail to avoid obscuring aspects of the embodiments.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The perspective view which shows the two layers which concern on this invention arrange | positioned for every layer at the lamination direction is represented. FIG. 2 represents a top view of the assembled layer of FIG. 1 with the welding pass and the welding direction indicated by lines and arrows, respectively. Fig. 4 represents a perspective view of a partially assembled insulation unit of the present invention with four sides welded in three ways. FIG. 4 represents a perspective view of a thermal insulation unit of the present invention having a spacer partially inserted into the pocket of the unit. Fig. 4 represents a perspective view of a thermal insulation unit of the present invention having a spacer inserted almost completely into the pocket of the unit. FIG. 4 represents a perspective view of a fully assembled thermal insulation unit of the present invention sealed by ultrasonic welding after degassing a pocket with spacers. The top view of the heat insulation boat comprised by the four heat insulation units which concern on this invention is shown. The heat insulation board comprised by the four heat insulation units which concern on this invention, Comprising: The schematic of the heat insulation board of this invention which has arrange | positioned the three layers laminated | stacked by offsetting in the horizontal direction is shown.

1 to 6 show in sequence the different steps of the method for producing the insulation unit 1 according to the invention with ultra-low thermal conductance characteristics.
In the following, ultra-low thermal conductance should be interpreted as a low thermal conductivity of 1 W / m · K or less and generally 0.1 W / m · K or less. In particular, FIG. 1 shows a first layer 2 and a second layer 3, for example showing a very thin aluminum foil having a typical length L and a width W of 50 cm, each side The side portions 5 are arranged in parallel to each other in the stacking direction. However, the material can be selected in principle from any material that enables the formation of a stable joint by high frequency welding. For example, iron, stainless steel, copper, composite material, carbon fiber, carbon fiber reinforced polymer (CFRP) and thermoplastic resin. Further, FIG. 2 shows a state in which ultrasonic welding or high-frequency welding 7, 7a, 7b is performed counterclockwise on the foils 2, 3 laminated for each layer. In order to ensure the maximum heat insulation from each heat insulation unit 1, welding is performed close to the side portions 5 of the foils 2 and 3. In the present embodiment, the foils 2 and 3 are welded by a double weld seem 7, i.e., by means of a welding path where the two do not parallel or intersect, The risk of leakage is reduced. FIG. 3 shows the foils 2 and 3 with pockets 6 which are sealed by a double seam weld 7 on one side and open in a cavity on the other unwelded side. As shown in FIGS. 4 and 5, a spacer 4 of suitable material is inserted into the cavity. The main purpose of the spacer 4 is first to ensure a minimum amount of direct bonding between the two foils 2 and 3, and secondly to ensure high mechanical stability. The spacer material can be freely selected as long as the overall thermal conductivity of the spacer 4 can be maintained at an acceptable level over the intended service life of the unit 1. Table 1 below shows a non-exhaustive list of spacer materials that can be used and a typical bulk thermal conductivity or conductivity range at room temperature and atmospheric pressure.

  However, the spacer 4 is interpreted herein in the broadest sense to meet the above objectives while maintaining low thermal conductivity, with minimal direct bonding between the foils and maintaining high mechanical stability. Should be. Other possible examples may use a spacer 4 with at least partly hollow parts in a wire skeleton having the required shape, or simply a foil material in a preformed cavity. It is also possible to expect that the rigidity can be maintained. In these particular examples, it is the vacuum created in the pocket 6 that contributes mainly to the low thermal conductivity.

  Finally, as shown in FIG. 6, the heat insulating unit 1 is completed when the spacer 4 is completely inserted and then deaeration and the two foils 2 and 3 are sealed by ultrasonic welding.

The schematics of FIGS. 7A and 7B consist of several insulating units 1 encapsulated at least partially with a high-resilient foam 11 such as polyurethane foam (PU), An insulating board / panel 8 having a matrix shape is illustrated. FIG. 7A shows a top view and a side view of an embodiment in which four units 1 covered with PU are arranged in a two-dimensional matrix shape. The general volume when applying heat insulation of liquefied gas such as LNG, LPG or LEG suitable for the heat insulation board 8 is about 1000 × 1000 × 50 mm ³ . However, of course, these dimensions should be adapted according to the specific needs. FIG. 7B shows these six boards 8a-f being arranged in three layers 12 ′, 12 ″, 12 ′ ″ and attached to the outer wall 9 of the liquid storage tank 10. . In order to reduce the thermal conductivity bridge between the tank 10 and the peripheral area (15) outside the tank 10 and the board 8, two adjacent layers 12 ', 12'', 12 The horizontal position of '''is shifted from side to side. Unit 1 is shown with only two upper layers 12 ', 12''. In the particular embodiment shown in FIG. 7B, each unit 1 is fully encapsulated with PU11. However, in another embodiment of the present invention, several units 1 may be stacked directly on top of each other without adding (providing) PU 11 in between. Furthermore, in another embodiment of the present invention, only some of the units 1 may be completely encapsulated and the other may be partially encapsulated. It is also a possible embodiment of the present invention to completely remove a part of the unit 1 or the surrounding encapsulant. In FIG. 7B, connection areas 13 ′, 13 ″ are shown in which different boards 8a-f are interconnected in the lateral direction, ie 8a-8b, 8c-8d, 8e-8f. Has been. The connection regions 13 ′, 13 ″ are preferably filled with a low conductivity material such as PU foam. Furthermore, the lowermost layer 12 ′ ″ shows fastening means 14 such as bolts / pins that can ensure a mechanically stable connection between the insulation board and the tank 10.

  The ultrasonic sealing method can generate fluid tight joints that last for a long time when welded with a super thin metal film with a thickness in the range of 30 μm to 800 μm, for example. According to the steps of the method described above, the ultra-thin thermal insulation unit 1 has ultra-low thermal conductance characteristics even when it is lowered to a cryogenic temperature, for example, a general liquid hydrogen or helium temperature range, across the vacuum and the spacer portion of the unit 1. Is obtained.

  In the foregoing description, various aspects of the apparatus according to the present invention have been described with reference to exemplary embodiments. For purposes of explanation, specific symbols, systems and configurations have been provided so that the apparatus and its operation can be better understood. However, this description should not be construed as limiting. Various modifications and variations of the illustrated embodiments of the apparatus, as well as other embodiments, which will be apparent to those skilled in the art belonging to the disclosed invention, are considered to be within the scope of the invention.

1 Insulation unit 2 First layer (foil)
3 Second layer (foil)
4 Spacer 5 Side (boundary)
6 pockets 7, 7a, 7b, 7c, 7d welding (ultrasonic welding, high frequency welding, seam welding)
8, 8a, 8b, 8c, 8d, 8e, 8f Thermal insulation board / panel (thermal insulation)
9 Wall 10 Tank (container)
11 Polyurethane foam (PU) (encapsulation material) (high resilience foam)
12 ′, 12 ″, 12 ″ ′ Layers 13 ′, 13 ″, 13 ′ ″ Connection region 14 Fastening means 15 Peripheral region (outside)
L, W unit distance

Claims (17)

A method for producing a thermal insulation unit (1) comprising the following steps having a long service life at cryogenic temperature,
-Placing the second layer (3) of at least one foil on the first layer (2) of at least one foil in a layered relationship, layer by layer;
The first layer (2) of the at least one foil and the second layer (3) of the at least one foil are joined by ultrasonic welding (7a, 7b) and at least one pocket (6 An opening having a
-Inserting at least one spacer (4) into the at least one pocket (6), the total outer volume of the at least one spacer (4) being greater than the inner volume of the at least one pocket (6); It ’s getting smaller,
-After degassing (exhausting) the pocket (6) in which said at least one spacer is inserted;
A method for manufacturing a heat insulating unit, characterized in that the pocket (6) into which the at least one spacer is inserted is sealed by ultrasonic welding (7c, 7d).   The ultrasonic welding (7a, 7b, 7c, 7d) is performed along the boundary (5) of the foil (2, 3) layer-by-layer assembled. The manufacturing method of the heat insulation unit of Claim 1.   At least a portion of the ultrasonic welding is performed along at least two parallel or generally parallel paths (7, 7a, 7b) to produce a plurality of seam welds (7). Item 3. A method for producing a heat insulation unit according to Item 1 or 2.   The method for manufacturing a heat insulating unit according to any one of claims 1 to 3, wherein a pressure inside at least one inside the at least one pocket is 25 kPa (that is, 0.25 bar) or less.   5. The method of manufacturing a heat insulating unit according to claim 4, wherein the pressure inside at least one of the at least one evacuation pocket (6) is not more than 10 kPa (0.1 bar).   The heat insulation according to any one of claims 1 to 5, wherein the at least one layer is formed of at least one metal, at least a metal alloy, or a combination of the metal and the metal alloy. Unit manufacturing method.   The thickness of the said foil (2, 3) is 1 mm or less, The manufacturing method of the heat insulation unit of any one of Claim 1 thru | or 6 characterized by the above-mentioned.   The thickness of the said foil (2, 3) is 0.1 mm or less, The manufacturing method of the heat insulation unit of Claim 7 characterized by the above-mentioned.   The composition material of the spacer is such that the overall thermal conductivity of each unit (1) withstands a pressure of 1 W / m · K or less and at least 1 bar, and further has a significant mechanical deformation ( The method for manufacturing a heat insulating unit according to any one of claims 1 to 8, wherein significant mechanical deformation is selected so as not to occur.   The spacer is made of at least one material selected from the group consisting of cork, cotton, ceramic fiber, polystyrene foam, fiber glass, pearlite, low density polymer, polystyrene, rice husk, airgel, and wood. The manufacturing method of the heat insulation unit of any one of Claims 1 thru | or 9.   The insulation board (8) attached to the outer and / or inner wall (9) of the fluid storage container (10) having an average fluid temperature different from the ambient temperature of the outer (15) of the fluid storage container (10). The insulating board comprising at least a unit (1) obtained by the method according to any one of claims 1 to 10.   The heat insulation board (8) includes a plurality of heat insulation units (1) that can be attached to the outer and / or inner wall (9) of the fluid storage container (10) in at least a two-dimensional matrix shape. The heat insulation board according to claim 11, wherein the heat insulation board is provided.   The matrix shape includes two or more layers (12 ′, 12 ″, 12 ′ ″) of heat insulating units, and the horizontal position of one layer (12 ″) is a plurality of adjacent layers (12 The thermal insulation board according to claim 12, characterized in that it is offset with respect to ', 12' '').   The heat insulation board according to claim 12 or 13, wherein the average fluid temperature is equal to or lower than the ambient temperature.   The thermal insulation board according to claim 14, wherein the average fluid temperature is between 0K and 200K.   16. A liquefied gas storage tank (10) comprising at least one thermal insulation board according to any one of claims 11 to 15, mounted on the outside and / or inside of the tank wall (9).   The liquefied gas storage tank according to claim 16, wherein the tank is in indirect contact with the fluid during use of the heat insulating wall (9).

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