JPH04258598A - Vacuum type heat insulating panel for super low temperature cargo storage tank - Google Patents

Abstract

PURPOSE:To obtain higher heat insulation properties by a simple heat insulating construction by constituting an heat insulating panel for a cargo storage tank in a liquefied gas carrying vessel by an airtight container and core materials filling the container, and evacuating the container. CONSTITUTION:With the tank for containing super-low temperature cargoes such as LPG loaded on a liquefied gas carrying vessel, a vacuum type heat insulating panel 5 constituting a vacuum type heat insulating construction of the tank 2 is mounted on its outer peripheral surface. In this case, the vacuum type heat insulating panel 5 consists of an airtight container composed of a low temperature side inner surface material 11 formed along the outer peripheral surface of the tank 2 and an ordinary temperature side surface material 10 arranged spaced apart outwardly from the inner surface material 11, and core materials 12 made of organic foam, etc., filling the container. The inside of the container is evacuated after it is filled with the core materials 12, and then sealed. Further, unevenness and embossments 14 are provided on the surface of the ordinary temperature side surface material 10 for the surface material to have flexibility relative to the contraction of the tank 2 and smoothly follow the contraction of the tank.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum insulation panel for a tank, and more particularly to a vacuum insulation panel suitable for a cryogenic cargo storage tank such as a cargo storage tank of a liquefied gas carrier.

0002

[Prior Art] As shown in FIG. 5, a conventional liquefied gas carrier has a cargo storage container (hereinafter referred to as "tank") 2 attached to its hull 1 through a cylindrical skirt 3. Insulation 2 is performed by attaching a multilayer insulation structure 30 to the outer surface of the tank 2 by processing organic foam insulation materials such as polyurethane foam, postyrene foam, and phenol foam singly or in combination into a panel or rod shape. It is. Note that the reference numeral 4 in FIG. 5 indicates a tank cover.

0003

[Problems to be Solved by the Invention] However, in recent years, due to the desire to save energy, there is a tendency for tanks with even higher thermal insulation properties to be required in order to suppress the evaporation of the liquefied gas cargo as much as possible.

[0004] In response to this requirement, the conventional techniques have the following problems.

That is, an extension of the prior art would be to increase the thickness of the heat insulating material in FIG. However, if the heat insulating material constituting the heat insulating structure is simply made thicker, in order to transport the same amount of cargo, the hull 1 and tank cover 4 will need to be expanded by the thickness of the heat insulating material due to space limitations. Such an enlargement of the hull 1 will lead to a deterioration in the propulsion performance of the ship and an increase in the required power.On the other hand, if the hull shape is kept constant, the cargo loading capacity will have to be reduced.

[0006] As a means of solving this problem, a vacuum insulation structure can be cited as a structure with better insulation properties. Although a structure using a double-shell tank has been known as a vacuum insulation structure, there is no example of this being applied to a large-capacity cargo tank. Furthermore, if one attempts to insulate a ship using a vacuum, a structure can be considered in which a vacuum is created by sucking the entire insulation structure 31 consisting of a heat insulating material and a hold with a pump 32, as shown in Figure 6. However, in this case there are the following problems. (1) It is necessary to equip the hull 1 with a large-capacity vacuum pump. (2) Adjacent tanks and hull compartments must be reinforced to withstand the vacuum. (3) Piping connected to safety valves and holds must be vacuum resistant. (4) Every time the interior of the vessel is inspected, such as when docking or docking, it is necessary to return the vessel to atmospheric pressure or to evacuate it, creating new work for the crew. (5) In terms of reliability in an emergency, if the vacuum is broken for some reason (accident, etc.), the insulation properties will drop all at once, sudden pressure fluctuations will occur, or the insulation properties will suddenly deteriorate, resulting in liquefied gas being a cargo. Problems such as increased evaporation of water occur, and emergency responses to these problems become complicated.

[0007] The present invention aims to solve these problems, and is intended to provide a heat insulating panel for a storage tank for ultra-low temperature cargo such as LNG. An airtight container is formed by the side inner surface material and the normal temperature side surface material disposed outside the inner surface material at a distance, and after filling the container with a breathable heat insulating material, the container is evacuated. The objective is to provide a vacuum-type insulation panel that has excellent insulation properties as a insulation panel for ultra-low temperature cargo storage tanks.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the vacuum insulation panel for a tank for storing ultra-low temperature cargo of the present invention is provided. An airtight housing consisting of a low-temperature inner surface material made of an airtight thin plate that can be attached closely to the outer circumferential surface of the housing, and a room temperature surface material made of an airtight thin plate placed at a distance outside the same inner surface material. The present invention is characterized in that it comprises a container and a core material filled in the container, and that the container is evacuated after being filled with the heat insulating material.

[0009]

[Function] In the vacuum insulation panel of the ultra-low temperature cargo storage tank of the present invention described above, the vacuum insulation panel manufactured at a dedicated factory is attached to the outer surface of the tank, and the joints are filled with polyurethane foam etc. A thermal insulation structure is constructed. The insulation performance of this vacuum insulation panel is approximately 3 times higher than that of conventional insulation materials such as polyurethane foam.
Since it has double the performance, the insulation effect of the entire insulation structure is at least twice as much as that of the conventional one, and the same performance requirements can be met with half the thickness of the insulation material of the conventional insulation method. .

0010

[Embodiment] A vacuum insulation panel for a cryogenic cargo storage tank as an embodiment of the present invention will be explained below with reference to the drawings. Fig. 1 is a side sectional view, Fig. 2 is a front view of main parts, and Fig. 3 is Fig. 2. 4 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a sectional view taken along line BB in FIG. Note that the same reference numerals in FIGS. 1 to 4 as in FIGS. 5 and 6 indicate substantially the same members.

[0011] The vacuum insulation panel for a tank for storing ultra-low temperature cargo in this embodiment is intended for a spherical tank 2, but it goes without saying that it can be applied to rectangular tanks as well as spherical tanks.

In FIG. 1, on a hull 1 of a liquefied gas carrier, a tank 2 for storing cryogenic cargo such as LNG has a cylindrical support usually called a skirt 3 that joins the tank 2 to the hull 1. A vacuum heat insulation panel 5 that constitutes a vacuum heat insulation structure of the tank 2 is attached to the outer peripheral surface of the tank 2.

Next, the vacuum heat insulating panel 5 will be explained with reference to FIGS. 2 to 4.

The vacuum heat insulating panel 5 includes a low-temperature side inner surface material 11 shaped along the outer peripheral surface of the tank 2, and a normal temperature side surface material 10 disposed outside the low-temperature side inner surface material 11 at a distance.
The core material 12 is filled in the airtight container.

Reference numeral 13 indicates that the vacuum insulation panel 5 is connected to the tank 2.
The flange portion 13 is shown for attachment to the vacuum insulation panel 5, and the flange portion 13 also serves as a joint portion of the vacuum insulation panel 5.

The vacuum heat insulating panel 5 is placed between stud bolts 15 arranged in advance in the latitude direction on the surface of the tank 2, and is attached to the outer circumferential surface of the tank 2 via the flange portion 13 with washers 16 and nuts 17. Low temperature side inner material 1
1 are successively attached to the entire outer periphery of the tank 2 while keeping them in close contact with each other. Note that it is preferable to use a self-locking nut as the nut 17 to prevent loosening.

Room temperature side surface material 10 and low temperature side inner surface material 11
For example, stainless steel foil or aluminum foil with a thickness of 0.3 mm or less is suitable, since the cargo is LNG at a low temperature of about -160°C, and when the cargo is LPG, the temperature is -45°C. Since the temperature is as low as 0.degree. C., for example, steel foil, engineered plastic, or a laminate film made of a combination of metal foil and plastic is suitable.

It is desirable that the surface of the room-temperature side surface material 10 be provided with irregularities or embossing 14 so that it has flexibility and can smoothly follow the shrinkage of the tank 2. Further, in the case of materials having a large difference in coefficient of linear expansion between the tank material 2 and the low temperature side inner surface material 11, it is desirable to provide embossing on the surface of the low temperature side inner surface material 11 in order to relieve stress.

The core material 12 is preferably an organic foam from the viewpoint of light weight and high heat insulation properties, but it may also be made of inorganic foam or organic/inorganic powder depending on the required heat insulation performance and weight restrictions. .

On the other hand, the joints between the vacuum heat insulating panels 5 are constructed as follows. That is, on the low-temperature side of the joint between the vacuum-type heat-insulating panels 5, highly elastic heat-insulating material 18 (for example, It is filled with a filler such as glass wool or soft urethane.

[0021] Furthermore, a material having a linear expansion coefficient close to that of the tank 2 (for example, reinforced phenol foam, polyurethane foam, etc.) may be used to prevent stress from occurring.

On the other hand, the room-temperature side of the joint is filled with a foam material 19 formed by in-situ foaming of polyurethane foam, from the viewpoint of improving the insulation properties and the continuity and airtightness between the vacuum insulation panels 5.

Furthermore, from the viewpoint of flexibility to follow the expansion and contraction of the tank 2, the surface material 10 on the room temperature side is used as the surface material 20 at the joint.
A foil that is equal to or thinner than the inner material 11 on the low-temperature side is used, and its four circumferences are attached to the ends of the vacuum heat insulating panel 5 with adhesive tape 21.

As mentioned above, the normal temperature side surface material 10 and the low temperature side inner surface material 11 are usually those with a thickness of 0.3 mm or less, but if these are made thinner, the flange portion 13 may be reinforced. It is necessary to. Further, each core portion 12 is made by sealing the hole by drawing a vacuum from a hole (not shown) in advance.

[0025] Then, in the airtight container as described above,
An independent vacuum insulation panel is created by filling an airtight container with a breathable insulation material and sealing it in a vacuum.In this case, the degree of vacuum is 1To to increase the insulation effect.
It is desirable to set it to rr or less. Further, as the breathable heat insulating material, inorganic or organic powder or granules or inorganic or organic foam can be used as described above, but organic foam is best from the viewpoint of heat insulation and light weight. The thus formed vacuum insulation panels 5 are sequentially fixed to the entire outer circumferential surface of the tank 2 using stud bolts 15 welded to the tank 2 surface in advance, and then expanded and contracted to the low temperature side of the joint between each vacuum insulation panel. Fill the tank with highly flexible glass wool or phenol foam with a coefficient of linear expansion close to that of the tank material, and on the room temperature side, make polyurethane foam by foaming on site to fill the joints.

Thereafter, a surface material (aluminum foil or stainless steel foil) is attached to the joint surface using double-sided tape to form a vacuum insulation structure for the tank 2.

[0027] The vacuum heat insulation panel having the above-mentioned configuration is as follows:
It has better insulation effects than conventional insulation materials. That is, according to the experimental results, the thermal conductivity λ1 of polyurethane foam at room temperature is λ1 = 0.018 to 0.020 kcal/mh°C, whereas the thermal conductivity of the vacuum panel (single unit) of the present invention at room temperature The conductivity λ0 was 0.0050 to 0.0060 kcal/mh°C, and it was found that the vacuum insulation panel of the present invention had a heat insulation effect about three times that of conventional heat insulation materials.

[0028]

[Effects of the Invention] As detailed above, the vacuum insulation panel for an ultra-low temperature cargo storage tank of the present invention provides the following effects and advantages. (1) Independent vacuum insulation panels have higher insulation properties than conventional insulation materials, and by installing them, it is possible to provide high insulation properties for storage tanks, and if the required performance is the same, it is better than conventional insulation materials. Can reduce insulation thickness. (2) It is possible to provide an insulation structure that is more reliable and easier to maintain than the conventional vacuum insulation system. (3) A highly insulated structure can be provided without changing the strength of conventional hulls and tanks, and without changing the operation of related cryogenic equipment.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a vacuum insulation panel for a cryogenic cargo storage tank as an embodiment of the present invention.

FIG. 2 is a front view of the main parts.

FIG. 3 is a sectional view taken along the line AA in FIG. 2;

FIG. 4 is a sectional view taken along the line BB in FIG. 2;

FIG. 5 is a side sectional view showing a heat insulation structure of a conventional ultra-low temperature cargo storage tank.

FIG. 6 is a side cross-sectional view showing a heat insulating structure that has a vacuum structure as a whole.

[Explanation of symbols]

1 Hull of liquefied gas carrier 2 Cargo storage container (tank) 3 Skirt 4 Tank cover 5 Vacuum insulation panel 10　Normal temperature side surface material 11 Low temperature side inner material 12 Core material 13 Flange part 14 Emboss 15 Stud bolt 16 Washer 17 Nut 18 Filling material 19 Foam material 20 Surface material for joints 21 Adhesive tape 30 Multi-layer insulation structure 31　　Insulation structure (due to overall vacuum) 32 Vacuum pump

Claims (1)

[Claims] [Claim 1] A heat insulating panel for a storage tank for ultra-low temperature cargo, the heat insulating panel comprising: an inner material on the low temperature side made of an airtight thin plate that can be attached closely to the outer peripheral surface of the tank; An airtight container configured with room-temperature surface materials made of airtight thin plates arranged at intervals, and a core material filled in the container, and the container is filled with the heat insulating material. A vacuum-type insulation panel for an ultra-low temperature cargo storage tank, which is characterized by being evacuated after being evacuated.