JPH0761493A - Panel for heat insulation of extremely low temperature tank - Google Patents

Abstract

PURPOSE:To provide a panel for heat insulation which is superior in various characteristics required for a panel for extremely low temperature heat insulation, and does not crack when it is installed under a restrained condition on a tank, and exposed to a cooling and normal temperature repeatedly by a method wherein a low temperature side heat insulating layer is constituted of a plate shape polystyrene foamed body with a plurality of slits, and the structure of a panel for heat insulation, which is composited, is specified. CONSTITUTION:As a low temperature side heat insulating layer 1 of a composed panel for heat insulation, a plate shape polystyrene foamed body is used. A plurality of slits are provided on one surface of the low temperature layer 12, and it is preferable to carve and arrange the direction of the slits in the same direction as the equator direction of a spheroidal tank. The flexibility is also imparted in the lateral direction. For a normal temperature side heat insulating layer 11, a general heat insulating material with a heat insulating effect can be used, and the normal temperature side heat insulating layer 11 is laminated on the low temperature layer 12 while leaving a joint part for four edges, and a reinforcing mesh 14 is inserted on the lamination interface. Also, a reinforcing mesh 15 is laminated to cover the slits of the low temperature layer 12. Thus, the slits are provided on the low temperature layer 12, and the temperature stress becomes smaller than the resistance force of the material, and the panel does not break even under an extremely low temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic tank heat insulating panel used for a heat insulating wall for keeping cold of a cryogenic tank and a heat insulating structure for a cryogenic tank using the same.

[0002]

2. Description of the Related Art Several proposals have been made for cryogenic tank heat insulation panels used for cryogenic liquid storage tanks such as LPG, LNG, and liquid nitrogen. Regarding a cryogenic tank heat insulation panel in which two heat insulation layers are combined, Japanese Patent Publication No. 60-26003 and Japanese Patent Publication No. 60-54168 are available.
No.

Japanese Patent Publication No. 60-26003 relates to a method for molding a curved heat insulating panel, in which the low temperature side (tank side) is a foamed phenol resin mixed with reinforcing fibers and the low temperature side (tank side). It is described that a compound curved surface heat insulation panel whose outside air side) is foamed polyurethane can be used as a cryogenic tank heat insulation panel. Further, Japanese Patent Publication No. 60-54168 relates to a method for forming a heat insulating panel for forming a heat insulating wall. In that publication, a foamed phenol resin formed by foaming phenol in a state where a low temperature side contains a reinforcing fiber. And the composite heat insulation panel whose normal temperature side is polyurethane foam,
It is described that it can be used as a panel for insulating a cryogenic tank.

Regarding the single layer, Japanese Patent Publication No. 63-30
In 557, closed-cell rigid urethane foam is used as a cryogenic tank insulation panel.

However, the characteristics required for a cryogenic heat insulating panel at −42 to −196 ° C. are low thermal conductivity, change over time in cooling and heating cycles, thermal shock durability, thermal shrinkage coefficient,
In terms of construction, processing, flexibility, flame resistance, etc., all of them must have excellent performance, and until now, there has been no sufficiently satisfactory cryogenic tank insulation panel.

Further, in addition to these characteristics, in the case of a composite heat insulating panel, when the heat insulating panel is installed on a tank in a restrained state and cooled, there is a problem that a layer on the low temperature side is cracked. This may be broken in a short time, or it may be broken by repeating cooling and normal temperature, but once the composite heat insulation panel breaks, cold air convection to the cracked part and a cold spot occurs. It will be. And, when it expands, heat transmission increases, which leads to a performance defect. In other words, when cooled down from room temperature to extremely low temperature with restraint, thermal stress (thermal stress) occurs, and if the resistance of the heat insulation panel is weak, this thermal stress cannot be absorbed and the stress is broken. Will be absorbed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cryogenic tank heat insulation panel which can solve such problems.

[0008]

The inventors of the present invention have conducted extensive studies to achieve this object, and as a result, have adopted a specific material for the heat insulation layer on the low temperature side of the composite heat insulation panel, and The present invention has been completed by finding out that the above-mentioned problems can be solved by making a specific structure of the heat insulating panel that has been realized.

That is, the present invention is as follows. 1. A low temperature side heat insulating layer made of a plate-shaped polystyrene foam having a plurality of slits, a room temperature side heat insulating layer which is smaller than the low temperature side heat insulating layer and is laminated on the low temperature side heat insulating layer leaving four side joints, and the low temperature side A cryogenic tank heat insulation panel, characterized in that a reinforcing mesh is interposed at a laminated interface between the heat insulation layer and the room temperature side heat insulation layer. 2. The cryogenic tank heat insulation panel according to item 1, wherein a reinforcing mesh is laminated so as to cover a plurality of slits of the low temperature side heat insulation layer made of a plate-shaped polystyrene foam. 3. The cryogenic tank heat insulation panel according to the above 1 or 2, wherein a moistureproof layer is provided outside the room temperature side heat insulation layer. 4. The cryogenic tank heat insulation panel according to the above items 1 to 3, which has a concave curved surface structure. 5. A heat insulating structure for a cryogenic tank, characterized in that a plurality of the cryogenic tank heat insulating panels according to the preceding paragraph 1 are mounted on an outer surface of a spherical tank, and a joint material is provided at a portion adjacent to the heat insulating panel.

In the cryogenic tank heat insulating panel of the present invention, it is important to use a plate-like polystyrene foam for the low temperature side (tank side) heat insulating layer (hereinafter referred to as the low temperature layer) of the composite heat insulating panel. is there. The expansion ratio and thickness of this plate-like polystyrene foam are determined by the types of cryogenic substances to be stored or transported, the types of tanks to be applied, that is, LNG transport tankers, underground storage tanks and pipe covers,
Since the size and the cold storage state are different from each other, the combination may be determined each time.

However, the low temperature layer basically has a closed cell structure. The plate-shaped polystyrene foam having this structure is obtained by intermittently or continuously (uniaxially) pressing a bead foam molding or an extrusion foam molding. For example, it can be obtained by the method described in JP-B-60-56095. The plate-like polystyrene foam obtained by pressing in this way has flexibility in the pressing direction. This is cut into a predetermined shape to form one low temperature layer.

The low temperature layer is required to have a plurality of slits on one side thereof. The shape of the plurality of slits is such that the interval is less than or equal to the thickness of the low temperature layer and the width is 0.5.
It is preferable that the thickness is 10 mm and the depth is 1/2 or more of the thickness of the low temperature layer. When the cryogenic tank heat insulation panel of the present invention is applied to, for example, a spherical tank, it is desirable that the slits be arranged in the same direction as the equatorial direction (lateral direction) of the spherical tank. Flexibility is also imparted in this lateral direction.

The provision of such slits is peculiar to the above-mentioned material, and is for preventing cracks (thermal cracks) at extremely low temperatures in both directions. That is, in the low temperature layer itself of the material, the resistance of the material is greater than the thermal stress (δ = E · dΔT) in its direction (flexible direction), and the elongation (%) of the material is also the amount of thermal strain. (Ε = d
Since it is larger than ΔT), it has resistance to withstand thermal stress even when used in a restrained form at cryogenic temperature, but since the other direction (rigid direction) cannot satisfy the above condition, The probability of breaking in this direction is high. Therefore, in order to improve this point, a quasi-constraint form is created from the restraint form by inserting a slit in that direction as the means,
By relaxing the thermal stress and making it smaller than the resistance of the material, it is possible to prevent cracking in both directions at extremely low temperatures.

Since the room temperature side (outside air side) heat insulating layer (hereinafter referred to as the room temperature layer) is not exposed to severe conditions unlike the low temperature layer, a heat insulating material having a heat insulating effect can be generally used. As the heat insulating material, polyurethane, polystyrene, polyethylene foam or the like can be used. The polyurethane foam may be formed by forming a mold on the surface of the low temperature layer, injecting polyurethane into the mold, and foaming to mold the room temperature layer.
The polystyrene foam is a rigid extruded polystyrene foam such as "Styrofoam" (trade name, Dow Chemical Co., Ltd.) or the same material as the low temperature layer, for example "Styroflex" (trade name, Dow Chemical Co., Ltd.). ) Can be used. Further, the room temperature layer may be a multilayer of two or more layers, and the room temperature layer may be reinforced with a glass fiber mesh, a metal plate, a plastic plate or the like for the purpose of reinforcement.

The shape of the room temperature layer must be smaller than that of the low temperature layer, as shown in FIGS. This is because when the low temperature layer is laminated on the normal temperature layer, the joints are left on the four sides of the low temperature layer. An example of the shape of the joint is shown in FIGS. 2 and 4, and according to this, the width (A) of the joint is preferably 20 to 100 mm. Therefore, the size of the room temperature layer is preferably smaller than that of the low temperature layer and about 40 to 200 mm smaller than each of the four sides of the low temperature layer.

A reinforcing mesh is laminated at the interface between the low temperature layer and the high temperature layer. This is because the reinforcing mesh laminated on the interface prevents the cracks from propagating from the low temperature layer to the room temperature layer when the cracks are generated from the slit portion provided in the low temperature layer. In this case, as the reinforcing mesh, a non-woven fabric, a woven fabric, a knitted fabric or other sheet-like material made of inorganic fibers such as glass, metal fibers, organic fibers such as aramid can be used. The reinforcing mesh is bonded with an adhesive or by heat fusion. Since the reinforcing meshes overlap each other in the joined state with the adjacent panels to reinforce each other, the reinforcing mesh is 20 to 10 from the end surface of the low temperature layer.
It is desirable to provide it so as to project by 0 mm.

In the cryogenic tank heat insulation panel of the present invention, a reinforcing mesh can be laminated on the slit side surface of the low temperature layer forming a part thereof so as to cover the slit. This reinforcing mesh is used to prevent cracking of the low temperature layer. This reinforcing mesh has an extremely small amount of shrinkage even in a low temperature state, has the effect of suppressing the shrinkage of the low temperature layer and preventing the local occurrence of cracks from increasing. For this purpose, reinforcing meshes can be made of the same materials as the reinforcing meshes mentioned above, and are likewise glued or heat-sealed.

A moisture-proof layer can be provided on the outside air side of the cryogenic tank heat insulation panel of the present invention. This moisture-proof layer is for protecting the panel of the present invention from moisture due to the invasion of water vapor from the outside into the panel. As the moisture-proof layer, an iron thin plate having a thickness of 50 to 1200 μm, a metal plate such as an aluminum plate or a stainless plate, or a fiber reinforced plastic such as FRP is used.

An embodiment of a cryogenic tank heat insulating panel of the present invention will be described based on its manufacturing method with reference to FIGS. 1 and 2. The order of the steps is as follows.

(1) A plate-shaped polystyrene foam having a thickness of 100 mm, "Styroflex" (trade name, Dow Kako Co., Ltd.) and a polyurethane foam having a thickness of 100 mm were prepared. (2) One side of the plate-shaped polystyrene foam was slit. The slit spacing is 80 mm, the width is 5 mm, and the depth is 70.
It was mm. (3) The plate-shaped polystyrene foam and the polyurethane foam were cut into predetermined dimensions to obtain a low temperature layer (12) and a room temperature layer (11). (4) A urethane adhesive was applied to the low temperature layer (12) and the room temperature layer (11). At this time, glass cloth (1
4) and (15) were added. (5) The adhesive was applied to the moisture-proof layer (13) and the room temperature layer (11) before the adhesive was cured. (6) Put the composite obtained above in a tan buckle,
While curing the adhesive, the curved surface was formed by pressing with a jig having a curved surface, and compounded with the adhesive to obtain a cryogenic tank heat insulation panel of the present invention having a concave curved surface structure.

FIG. 3 shows a state in which the composite cryogenic tank heat insulation panel of the present invention thus obtained is mounted on the entire surface of the tank. FIG. 3 shows the heat insulating structure of the cryogenic tank in an easy-to-understand manner by cutting out a part of the exterior of the cryogenic tank. To attach the cryogenic tank insulation panel to the outer surface of the tank, for example, the tip portion of the stud bolt is welded to the tank surface and the stud bolt is used to press the panel to the tank surface (not shown). It is possible to adopt the means such as

FIG. 4 shows that the combined cryogenic tank heat insulation panel and another adjacent heat insulation panel and joint material (1
8) shows the state immediately before being coupled via (19). In FIG. 4, joint materials (18) and (19)
Are rigid urethane foam and glass fiber insulation, respectively. The joint material (18) has a moisture-proof layer attached so that its ears are exposed, and this is inserted into the joint portion with an adhesive and fixed. Further, in FIG. 4, the length of A is 20 to 100 mm, and the length of B is 0 to 20 mm.

As the joint material, a material similar to that of the room temperature layer or a material having appropriate heat insulation and flexibility such as a glass fiber heat insulating material, a soft urethane foam, and a silicone rubber sealant is used.

[0024]

[Effects of the Invention] All of them are excellent in various properties such as low thermal conductivity, aging characteristics of thermal cycle, thermal shock durability, heat shrinkage coefficient, construction, processing and flexibility required for a cryogenic heat insulating panel. It has high performance, and its insulation panel is installed on the tank in a restrained state, and it does not crack even if it is cooled and kept at normal temperature. In addition, by forming a slit in the low temperature side heat insulating layer, a semi-constraint form is created from the restraint form, and by reducing the thermal stress to less than the resistance of the material, it is possible to prevent cracking in both directions at extremely low temperatures. .

[Brief description of drawings]

FIG. 1 is a sketch of a cryogenic tank insulation panel of the present invention.

FIG. 2 is a side view of a cryogenic tank insulation panel of the present invention.

FIG. 3 is a schematic view of a cryogenic tank showing a heat insulating structure by a panel group for cryogenic tank insulating of the present invention mounted on the outer surface of the cryogenic tank.

FIG. 4 is a cross-sectional view showing a state in which the cryogenic tank heat insulation panel of the present invention is mounted on the surface of the tank, and the panels are immediately connected to each other through the joint material.

[Explanation of symbols]

 11 Room Temperature Side Insulation Layer 12 Low Temperature Side Insulation Layer 13 Moisture Proof Layer 14 Reinforcing Mesh 15 Reinforcing Mesh 16 Slit 17 Cryogenic Tank 18 Joint Material 19 Joint Material

Claims (5)

[Claims] 1. A low temperature side heat insulating layer made of a plate-shaped polystyrene foam having a plurality of slits, a room temperature side heat insulating layer smaller than the low temperature side heat insulating layer and laminated on the low temperature side heat insulating layer leaving four-sided joints. And a reinforcing mesh interposed at a laminated interface between the low temperature side heat insulating layer and the room temperature side heat insulating layer. 2. The cryogenic tank heat insulation panel according to claim 1, wherein a reinforcing mesh is laminated so as to cover a plurality of slits of the low temperature side heat insulation layer made of a plate-shaped polystyrene foam. 3. The cryogenic tank heat insulation panel according to claim 1, wherein a moisture-proof layer is provided outside the room temperature side heat insulation layer. 4. A structure having a concave curved surface on the low temperature side.
The panel for heat insulation of a cryogenic tank according to 3 above. 5. A cryogenic tank according to claim 1, wherein a plurality of the cryogenic tank heat insulating panels are mounted on an outer surface of a spherical tank, and a joint material is provided in a portion adjacent to the heat insulating panel. Heat insulation structure of the tank.