CN113302429A

CN113302429A - Heat insulation structure of tank for low-temperature fluid and construction method thereof

Info

Publication number: CN113302429A
Application number: CN202080009061.8A
Authority: CN
Inventors: 吉村和彦; 平川永晃; 林圣人; 笹野顺司
Original assignee: Nisshinbo Chemical Inc
Current assignee: Nisshinbo Chemical Inc
Priority date: 2019-01-18
Filing date: 2020-01-17
Publication date: 2021-08-24
Also published as: JPWO2020149392A1; WO2020149392A1; KR20210114404A

Abstract

The present invention provides a heat insulating structure for a low-temperature fluid tank, which is formed by a construction method comprising: a step of providing an elastic partition plate 2 on the outer side of the tank to divide the tank outer wall 1 into a plurality of sections X, and a step of filling and injecting foamed polyurethane 4a at least in the sections X.

Description

Heat insulation structure of tank for low-temperature fluid and construction method thereof

Technical Field

The present invention relates to a heat insulating structure formed on an outer wall of a tank for cryogenic fluid such as Liquefied Natural Gas (LNG) or liquid nitrogen, and a method for constructing the same.

Background

In recent years, regulations for exhaust gas of ships have been strictly strengthened from the viewpoint of environmental protection, and accordingly, introduction of ships using LNG as fuel has been advanced. LNG tanks are mounted on an LNG fuel ship and an LNG refueling ship that refuels such a ship.

As described above, the demand for LNG tanks is expected to increase not only for tanks installed on the ground but also for tanks for transportation and fuel in ships.

LNG has a boiling point of about-162 ℃ at normal pressure, and the LNG tank needs to be kept at a low temperature in order to suppress vaporization of LNG in the tank due to the external temperature of the tank. Therefore, the LNG tank is provided with a heat insulating structure on the outer wall.

In addition, it is also desired that a tank for storing a cryogenic fluid such as liquid nitrogen (boiling point at normal pressure: about-196 ℃) or liquid oxygen (boiling point at normal pressure: about-183 ℃) has excellent thermal insulation properties of the outer wall, as in the case of an LNG tank.

The heat insulating structure of the low-temperature fluid tank is generally composed of a heat insulating layer using a heat insulating material, and its application method is roughly classified into a plate application method and a spray application method.

The above-described plate construction method is a construction method in which a plurality of heat insulating plates made of rigid polyurethane foam (rigid PUF) or the like are fixed by attaching studs, nuts, brackets, or the like to a tank, thereby forming a heat insulating layer (for example, see patent document 1).

The above-described spray application method is an application method in which the outer wall of the low-temperature fluid tank is covered with a hard PUF spray (injection) to form a heat insulating layer (see, for example, patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese Utility model laid-open publication No. 61-156797

Patent document 2: japanese patent laid-open publication No. Sho 58-80071

Disclosure of Invention

The thermal insulation material made of a hard PUF has a larger linear expansion coefficient than a metal low-temperature fluid tank. Therefore, the heat insulating layer formed at normal temperature has a larger shrinkage amount than the tank when cooled by the cryogenic fluid, and generates stress in a direction parallel to the outer surface of the tank.

In addition, a metal low-temperature fluid tank has a high thermal conductivity, and starts to rapidly increase in temperature if a low-temperature fluid is discharged, whereas a hard PUF having a lower thermal conductivity starts to increase in temperature more slowly than the tank. Therefore, the thermal expansion of the heat insulating layer is slower than that of the can, and the stress generated in the heat insulating layer is likely to increase.

Further, during the cooling process and during the temperature rise, since the tank internal pressure rises with the evaporation of the gas, the tank expands, increasing the stress generated in the heat insulating layer.

In the above-described panel construction method, a heat insulating layer is formed by arranging a plurality of heat insulating panels so as to be laid, and a cushion material, for example, glass wool or the like, which is deformable in accordance with dimensional change or deformation caused by shrinkage or expansion of the heat insulating panels, is inserted into a joint portion between the heat insulating panels. This buffer material suppresses breakage such as cracking of the heat insulating layer due to stress caused by a difference in linear expansion coefficient or thermal conductivity between the can and the hard PUF.

However, the plate construction method requires a lot of labor and work time in the step of installing the heat insulating plates of a predetermined shape and a predetermined size one by one and the step of inserting the cushioning material into the joint. Further, the hard PUF must be formed into a predetermined shape and a predetermined size in advance in a factory in accordance with the shape of the can, and the cost is also increased.

On the other hand, in the above-described injection construction method, although a seamless heat insulating layer can be formed in a shorter period of time and at a lower cost, the hard PUF integrated by injection is likely to be damaged by cracks or the like due to the above-described stress.

Even if an anti-crack layer such as a glass mesh is provided at a predetermined thickness position of the heat insulating layer, it is difficult to prevent cracks of the heat insulating layer generated from the tank contact surface from reaching the surface.

In patent document 2, when the hard PUF is ejected, the separator made of the hard PUF is stuck to the outer surface of the can, but the separator has no elasticity, and the separator does not divide the outer surface of the can into a plurality of regions but is a reference for forming the layer of the ejected hard PUF into uniform thickness. It is difficult to say that such a separator can alleviate stress generated in the heat insulating layer and sufficiently suppress the occurrence of cracks or the like in the heat insulating layer.

Therefore, when a failure occurs or when maintenance is performed regularly, the heat insulating layer formed by the conventional spray application method must repair a damage such as a crack generated when the cryogenic fluid tank is initially cooled or when the cryogenic fluid is discharged and the tank is heated.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a heat insulation structure for a cryogenic fluid tank, which has excellent heat insulation properties in external heat insulation of the cryogenic fluid tank, can suppress damage such as cracking caused by temperature change, is low in cost, and has excellent ease of construction, and a method of constructing the same.

The heat insulating structure of a low-temperature fluid tank of the present invention can effectively prevent damage such as cracks caused by temperature change by providing a predetermined elastic partition plate when foam-in-place polyurethane is formed on the outer wall of the tank by a spray application method or the like.

That is, the present invention provides the following [1] to [10 ].

[1] A heat insulation structure of a low-temperature fluid tank, comprising: an elastic partition plate which is arranged outside the tank and divides the outer wall of the tank into a plurality of subareas; and a foam-in-place polyurethane disposed at least within the partition.

[2] The heat insulating structure of a cryogenic fluid tank according to [1], wherein the elastic partition plate comprises an elastic material.

[3] The heat insulating structure of a cryogenic fluid tank according to [2], wherein the elastic partition plate is made of a composite material including the elastic material and a material having higher rigidity than the elastic material.

[4] The heat insulating structure of a tank for a low-temperature fluid according to item [3], wherein the material having higher rigidity than the elastic material contains at least a rigid polyurethane foam.

[5] The heat insulating structure of a low-temperature fluid tank according to any one of [2] to [4], wherein the elastic material contains at least one selected from glass wool, melamine foam, phenol foam, and flexible polyurethane foam.

[6] The heat insulating structure of a low-temperature fluid tank according to any one of [1] to [5], wherein the foam-in-place polyurethane is formed by laminating a plurality of layers on an outer surface of the tank, and a mesh-shaped reinforcing layer is provided between at least one of the plurality of layers.

[7] The heat insulation structure for a cryogenic fluid tank according to any one of [1] to [6], wherein the heat insulation structure for a cryogenic fluid tank includes a base layer in contact with an outer surface of the tank.

[8] The heat insulating structure of a low-temperature fluid tank according to any one of [1] to [7], wherein a moisture-proof layer containing at least one selected from a resin coating layer, an aluminum foil moisture-proof sheet, and an aluminum moisture-proof tape is provided on an outermost surface of the foam-in-place polyurethane.

[9] The heat insulating structure of a low-temperature fluid tank according to any one of [1] to [8], wherein the elastic partition plate has a height of 50 to 300mm and a width of 10 to 200 mm.

[10] A method for constructing a heat insulating structure of a low-temperature fluid tank, comprising: a step of arranging an elastic partition plate on the outer side of the tank to divide the outer wall of the tank into a plurality of subareas, and a step of filling and spraying foaming polyurethane at least in the subareas.

The heat insulating structure for a cryogenic fluid tank according to the present invention has excellent heat insulating properties in the external heat insulation of the cryogenic fluid tank, and can suppress damage such as cracking caused by temperature change, thereby reducing the burden of maintenance. Further, the construction is easier than the conventional plate construction method which is a general construction method at low cost.

In addition, according to the construction method of the present invention, the heat insulating structure can be appropriately formed.

Drawings

Fig. 1 is a schematic cross-sectional view of a heat insulating structure in example 1.

FIG. 2 is a schematic perspective view showing an example of a mode of forming partitions by combining elastic separators.

FIG. 3 is a schematic perspective view showing an example of a guide member of the elastic partition plate.

FIG. 4 shows an example of the shape of the elastic partition plate.

FIG. 5 is a schematic perspective view of a partition formed by combining elastic partition plates in a manner different from that of FIG. 2

FIG. 6 is an example of a composite material in an elastic separator.

Detailed Description

Hereinafter, the heat insulating structure of the low-temperature fluid tank and the method of constructing the same according to the present invention will be described in detail.

The heat insulation structure of the low-temperature fluid tank of the invention is provided with an elastic partition board which is arranged outside the tank and divides the outer wall of the tank into a plurality of subareas; and a foam-in-place polyurethane disposed at least within the partition.

By providing a predetermined elastic partition in the heat insulating layer of the foam-in-place polyurethane, stress generated in the heat insulating layer due to a temperature change is relaxed, and occurrence of damage such as cracking is suppressed, so that a good heat insulating performance can be maintained in the low-temperature fluid tank.

[ tank ]

The tank that forms the object of the heat insulating structure of the present invention is a tank for a cryogenic fluid. The tank is a tank for storing a fluid at a temperature lower than normal temperature, and the heat insulating structure of the present invention can exhibit excellent effects particularly in a tank for storing an ultra-low temperature fluid such as LNG, liquid nitrogen, liquid oxygen, or the like at a temperature lower than the freezing point, as described above. The tank is generally made of metal such as stainless steel.

The shape, size, and the like of the tank are not particularly limited, and the tank is generally spherical, square, cylindrical (cylindrical capsule shape), and the like, and may be mounted on a ship or the like or installed on the ground.

[ elastic partition board ]

The resilient partitions are arranged to divide the outer wall of the tank into a plurality of zones. And, foam-in-place polyurethane is provided in the partition.

The foamed-in-place polyurethane as the heat insulating material is partitioned by the elastic partition plate, and the elastic partition plate is elastically deformed in accordance with a dimensional change or deformation of the foamed-in-place polyurethane due to a difference in thermal shrinkage amount and thermal expansion amount from the tank, whereby occurrence of breakage such as cracking in the foamed-in-place polyurethane can be suppressed.

As described above, the elastic partition has elasticity that can deform in accordance with a dimensional change or deformation of the foam-in-place polyurethane, which is different from that of the tank.

When the in-situ foaming polyurethane is brought into contact with the outer surface of the low-temperature fluid tank, a dimensional change of about 5mm at maximum is generally generated at the tank contact surface of the in-situ foaming polyurethane, for example, per 1m length. Therefore, the elastic partition plate preferably has elasticity to return to the original width if the compression is released in the case of compressing 10mm in the width direction thereof. The elastic material in the present invention is a material having such properties.

The shape and size of the partition defined by the elastic partition are appropriately set in accordance with the shape, size, and the like of the tank. For example, at a capacity of about 100m³In the case of the above tank, the area of the partition defined by the elastic partition is preferably 0.1 to 1.5m from the viewpoints of heat insulation, suppression of occurrence of damage such as cracks in the in-place foamed polyurethane, and efficiency of construction²About 0.2 to 1.4m, more preferably²More preferably 0.3 to 1.3m²。

The installation interval of the elastic partition plates, at which the occurrence of breakage such as cracking in the foamed-in-place polyurethane can be suppressed, can be determined by calculation from the linear expansion coefficient of the material of the tank, the linear expansion coefficient, the tensile strength, the tensile elastic modulus, and the like of the foamed-in-place polyurethane. In a simple manner, the shrinkage of the foam-in-place polyurethane at the cooling temperature of the tank can be determined and estimated in consideration of the workability in the field.

For example, the linear expansion coefficient of the polyurethane foamed in situ is 5X 10^-5[/℃]In the case of (2), since it is confirmed that no damage such as cracking occurs until the shrinkage ratio of the in-place foamed polyurethane reaches about 1%, if the temperature difference between the outer surface of the tank and the atmospheric temperature is 200 ℃, the installation interval of the elastic partition plates is preferably 0.5 to 2m, more preferably 0.7 to 1.5m, and still more preferably 0.8 to 1.2 m.

From the viewpoint of ease of construction and the like, it is preferable that a plurality of the elastic partition plates are formed in a flat plate shape in advance, and the outer wall of the tank is partitioned into a plurality of partitions in a lattice shape having substantially the same area, such as a triangle or a quadrangle.

In addition, from the viewpoint of construction efficiency, the elastic diaphragm is preferably provided in a dome or a manhole as a tank opening cover, a boundary portion between a tank attachment such as a nozzle connection portion or a support leg portion and a tank main body, or a portion other than a complicated shape portion having a corner portion or fine irregularities.

The height of the elastic partition plate may be appropriately set according to the height (thickness) of the foam-in-place polyurethane provided outside the tank, but is preferably 50 to 300mm, more preferably 70 to 280mm, and even more preferably 80 to 250mm from the viewpoints of sufficient heat insulation and cost.

In addition, the elastic partition plate needs to have a width of a degree capable of relaxing stress generated in the foam-in-place polyurethane due to a temperature change of the tank. On the other hand, the larger the proportion of the foam-in-place polyurethane on the outside of the tank, the more excellent the heat insulation property, and therefore the width of the elastic partition plate is preferably not excessively large.

The width of the elastic partition plate depends on the area of the partition or the shape of the tank, but is preferably about 10 to 200mm, more preferably 20 to 180mm, and still more preferably 30 to 150 mm.

When the elastic partition has elasticity capable of withstanding the foaming pressure during the in-situ foaming polyurethane construction, the elastic partition may be formed of only an elastic material, but is preferably formed of a composite material including an elastic material and a material having higher rigidity (high rigidity material) than the elastic material.

By forming the elastic partition plate from such a composite material, the self-standing strength that can withstand the foaming pressure of the foam-in-place polyurethane can be easily maintained even if the width of the elastic partition plate is small.

In a preferred embodiment of the above elastic material, for example, the high-rigidity material is preferably a high-rigidity material that does not deform when a load of about 10mm compression is applied in the width direction of the elastic partition plate in a direction in which the material becomes the width direction of the elastic partition plate.

Specific examples of the elastic material include glass wool, melamine foam, phenol foam, flexible polyurethane foam, and the like, from the viewpoint of good adhesion to the in-place foamed polyurethane.

Specific examples of the high-rigidity material include a hard PUF. Preferably, a rigid PUF of the same kind as the foam-in-place polyurethane is used.

The elastic material and the high-rigidity material in the composite material may be used alone or in combination of two or more.

Specific examples of the elastic separator made of the composite material include a parallel structure in which the elastic material and the high-rigidity material are arranged in the width direction of the elastic separator, a sandwich structure in which the high-rigidity material is sandwiched between the elastic material and the elastic separator in the width direction of the elastic separator, and a sandwich structure in which the elastic material is sandwiched between the high-rigidity material and the elastic separator in the width direction of the elastic separator.

[ foam-in-place polyurethane ]

The in-situ foaming polyurethane is a hard PUF obtained by bringing a raw material liquid for a hard PUF and an in-situ foaming machine into a site of a tank to be constructed, and foaming and curing the hard PUF in the site, and is provided by a spray construction method, an injection construction method, or the like.

By constituting the heat insulating material with the polyurethane foam in place, the heat insulating material is more suitable for various tank shapes than the case of using the heat insulating plate, and can be easily constructed at low cost.

From the viewpoint of ease of application, the foam-in-place polyurethane is preferably provided by a spray application method.

In addition, in the above-described tank attachment member such as a dome or a manhole and a portion having a complicated shape having a corner or fine unevenness such as a vicinity thereof, it may be provided by an injection method so that the foamed-in-place polyurethane is uniformly provided to a fine part.

In such a portion having a complicated shape, a molded article provided with a hard PUF fabricated to match the shape may be filled with in-situ foaming polyurethane and integrated with the molded article. The present invention does not prevent the use of such a molded article in combination with a foam-in-place polyurethane.

As the in-situ foaming polyurethane, a hard PUF known as a heat insulating material can be used. The hard PUF may be a one-liquid type or a two-liquid type including a liquid containing polyisocyanate and a liquid containing polyol. As the blowing agent, known blowing agents can be used, and for example, Hydrofluoroolefin (HFO), Hydrochlorofluoroolefin (HCFO), Hydrofluorocarbon (HFC), water and the like are preferably used. These may be used alone or in combination of two or more.

The foam-in-place polyurethane is disposed at least in the zones divided by the elastic partition. The foam-in-place polyurethane may be provided at a height position that is substantially equal to a height position of the elastic bulkhead from the outer surface of the tank in a state where the elastic bulkhead is not completely covered. Alternatively, the elastic partition plate may be provided so as to be thick until it completely covers the outer surface of the tank, and may be provided at a position higher than the elastic partition plate by the height from the outer surface of the tank.

The foam-in-place polyurethane may be formed in a single layer or may be formed by laminating a plurality of layers on the outer surface of the tank in consideration of workability and the like.

[ mesh-like reinforcing layer ]

In the case where the in-place foamed polyurethane has a laminated structure of a plurality of layers as described above, it is preferable to provide a mesh-like reinforcing layer between at least one of the plurality of layers from the viewpoint of further improving the effect of suppressing damage such as cracking.

Examples of the mesh-like reinforcing layer include glass cloth (glass mesh), metal mesh, carbon cloth (carbon mesh), and natural fiber cloth. The mesh-like reinforcing layer may be formed of one kind alone, or two or more kinds may be used in combination.

The mesh-like reinforcing layer may be only 1 layer, or may be formed between a plurality of layers of the in-situ foaming polyurethane and provided with a plurality of layers. The mesh-like reinforcing layer may be formed on a part of the surface of the foam-in-place polyurethane layer, or may be formed on the entire surface.

[ base layer ]

The can outer surface also preferably has a substrate layer attached thereto. The base layer serves to buffer the transmission of expansion and contraction caused by a change in temperature of the outer wall of the tank to the foam-in-place polyurethane.

The base layer is preferably formed of, for example, a release film such as a polyethylene sheet, glass wool, melamine foam, an agricultural mulching film (an open-cell polyethylene film), or the like. The material for forming the base layer may be used alone or in combination of two or more.

The base layer may be formed so as to be in contact with a part of the surface of the outer surface of the tank, or may be formed so as to be in contact with the entire surface.

The elastic separator may be provided on the base layer, or may be provided in direct contact with the outer surface of the tank without interposing the base layer therebetween.

The thickness of the base layer is not particularly limited, and may be appropriately set within a range that does not interfere with the construction work.

[ moisture-proof layer ]

The outermost surface of the foam-in-place polyurethane is preferably provided with a moisture barrier. The moisture-proof layer comprises at least one selected from the group consisting of a resin coating layer, a moisture-proof sheet of aluminum foil, and a moisture-proof tape of aluminum. The moisture-proof layer preferably includes a resin coating layer from the viewpoint of sufficiently covering the surface irregularities of the foamed-in-place polyurethane and preventing a decrease in heat insulating performance due to internal condensation in the foamed-in-place polyurethane and deterioration of the foamed-in-place polyurethane. The moisture barrier may be a separate resin coating.

For the resin coating layer, for example, polyurea resin, epoxy resin, one-pack type acrylic emulsion, and the like are preferably used from the viewpoint of moisture resistance, adhesion to the foam-in-place polyurethane, and the like.

The moisture-proof layer preferably comprises an aluminum foil moisture-proof sheet or an aluminum moisture-proof tape from the viewpoint of moisture-proof effect and construction. The moisture-proof layer may be either an aluminum foil moisture-proof sheet or an aluminum moisture-proof tape, or both, and more preferably further comprises a resin coating.

The moisture barrier is preferably provided at least at the outermost surface of the foam-in-place polyurethane. In the case where the elastic partition is not completely covered with the foamed-in-place polyurethane, it is preferable that the exposed upper portion of the elastic partition and the outermost surface of the foamed-in-place polyurethane in the partition partitioned by the elastic partition are both covered with the moisture barrier.

The thickness of the moisture-proof layer is not particularly limited, and may be set in consideration of a sufficient moisture-proof effect, cost, construction efficiency, and the like. Usually about 0.5 to 10mm, preferably 1 to 8mm, and more preferably 2 to 7 mm.

The thickness of the resin coating is usually 0.5 to 10mm, preferably 1 to 8mm, and more preferably 2 to 7mm from the viewpoints of moisture-proof effect, cost, construction efficiency, and the like.

From the viewpoint of moisture-proof effect, cost, construction efficiency, and the like, the thickness of the aluminum foil in the aluminum foil moisture-proof sheet or the aluminum moisture-proof tape is preferably 0.1 to 0.001mm, and more preferably 0.05 to 0.003 mm. For example, as the aluminum moisture-proof tape, ST moisture-proof tape (thickness of tape: 0.5mm, thickness of aluminum foil: 0.007mm) manufactured by Kashida corporation can be preferably used.

[ working method ]

The method of constructing the heat insulating structure of the low-temperature fluid tank as described above is not particularly limited, but the construction method of the present invention described below can be easily and inexpensively constructed.

The construction method of the present invention comprises a step (1) of providing an elastic partition plate on the outer side of the tank to divide the outer wall of the tank into a plurality of partitions, and a step (2) of filling and spraying foamed polyurethane at least in the partitions.

These steps may be divided into work sections such as the upper part, the lower part, and the side surface part of the tank in consideration of workability in construction according to the shape, size, and the like of the tank, and construction may be performed for each work section.

(step (1))

In the step (1), an elastic partition is provided on the outer side of the tank to divide the outer wall of the tank into a plurality of partitions.

Preferred manners of the resilient partition and thus of the divided sub-areas are as described above.

The elastic partition is preferably provided by being attached to the outer wall of the tank with a double-sided tape or the like, from the viewpoint of ease of application, cost, and the like. For the above-mentioned adhesion, for example, a waterproof double-sided butyl tape or the like is preferably used.

Further, the elastic partition plate may be fixed to the outside of the tank by attaching a stud bolt, a nut, a bracket, or the like to the outer wall of the tank. However, the installation work of the stud bolts or the like is troublesome, and the elastic partition plate is not necessarily firmly provided on the outside of the tank by such a method. When the subsequent step (2) is to perform the spray foaming, the partition filled with the spray foaming polyurethane may be kept outside the tank.

As described above, the elastic partition is preferably provided so as to be partitioned into grid-like partitions. In this case, for example, as shown in fig. 2, the end portions in the longitudinal direction of one elastic partition plate 2 and the end portions in the longitudinal direction of the other elastic partition plate 2 may be combined with each other in a mortise-and-tenon manner in the arrow direction by the slits formed in the respective end portions to form the intersection. In fig. 2, 4 elastic partition plates 2 having the same shape are used and combined into a cross shape.

Alternatively, the partition may be formed easily by providing a guide member having a groove cut in the width of the elastic partition at a position of the intersection constituting the partition, the guide member corresponding to the number of the elastic partitions at the intersection. For example, by providing the guide member 10 cut with a cross groove as shown in fig. 3 at the position of the intersection of the 4 flat elastic partition plates and inserting the 4 elastic partition plates (not shown) into the guide member 10 in the direction of the arrow, it becomes easy to form the partition divided in a grid shape by the 4 elastic partition plates provided in a cross shape. The guide member is preferably made of the same material as the elastic partition plate.

In addition, when the elastic partition plate does not have a suitable strength enough to be self-supporting, the elastic partition plate may be set so as to be surely self-supporting by providing rigidity to the elastic partition plate by, for example, tightening the elastic partition plate with a tape or an adhesive tape or by placing the elastic partition plate in a bag and performing deaeration sealing to form a compressed state. The elastic partition plate is temporarily brought into a state of not having elasticity in such a compressed state, but in the subsequent step (2), after the foamed polyurethane is injected to the height position of the elastic partition plate in the partition, or during the filling, the compressed state is released by cutting the tape or the like, opening the bag, or the like, whereby the partition can be held in a stretchable state.

In addition, when the elasticity of the elastic partition plate is insufficient at the time of installation, the elasticity of the elastic partition plate may be improved by the foaming pressure at the time of the spray foaming in the subsequent step (2).

In the case where the elastic partition is formed of the composite material as described above, the elastic partition may be formed of the composite material in advance before being installed outside the tank, or the elastic material and the high-rigidity material may be combined at the time of installation.

The base layer may be provided in contact with the outer surface of the tank before or after the step (1).

Since the base layer is covered with the spray foaming urethane and fixed on the outer surface of the tank, the base layer can be temporarily fixed to such an extent that it does not fall off at the time of spray foaming in the subsequent step (2). For example, the base layer may be provided by adhering the base layer to the outer surface of the can using a spray adhesive, a double-sided tape, or the like.

(step (2))

In the step (2), the foamed polyurethane is filled and injected at least in the sections partitioned by the elastic partition.

Preferably, when the foam is injected into the partition, the foam is injected from the central portion of the partition so as to compress the elastic partition by the foaming pressure of the rigid PUF, and then the foam is injected around the elastic partition.

When the total thickness of the spray-foamed polyurethane layer is about 50mm or more, it is preferable to spray a plurality of layers until a desired total thickness is reached by making one layer about 30 to 50mm thick. After filling the spray-foamed polyurethane, if necessary, it is preferable to perform appropriate curing in the same manner as curing performed in a general spray method.

In the case of filling the above-mentioned injection-foamed polyurethane, it is preferable to fill the injection-foamed polyurethane so that the remaining portion is filled after performing injection foaming at a pitch of about 1 division from the viewpoint of dispersing and alleviating shrinkage of the hard PUF caused by the foaming heat after injection.

From the viewpoint of reinforcing the heat insulating layer of the spray foamed polyurethane, it is preferable that the height of the elastic partition plate is filled with the spray foamed polyurethane, the spray foamed polyurethane is covered with the mesh-like reinforcing layer, and the mesh-like reinforcing layer is further covered with the spray foamed polyurethane.

In order to prevent moisture of the spray foamed polyurethane, it is preferable that a moisture-proof layer is formed by applying a resin to the outermost surface of the spray foamed polyurethane after the step (2). The specific method for applying the resin is not particularly limited, and may be performed by, for example, brushing, rolling, spraying, or the like.

In order to improve moisture resistance, it is also preferable to form a moisture-proof layer using an aluminum moisture-proof tape or an aluminum foil moisture-proof sheet.

More preferably, an aluminum moisture-proof tape or an aluminum foil moisture-proof sheet is attached to the outermost surface of the spray foamed polyurethane, and a moisture-proof layer is formed by coating a resin on the surface. After the resin is coated on the outermost surface of the spray-foamed polyurethane, an aluminum moisture-proof tape or an aluminum foil moisture-proof sheet may be attached to form a moisture-proof layer, or a resin may be further coated to form a moisture-proof layer composed of at least 3 layers of a resin/aluminum moisture-proof tape or an aluminum foil moisture-proof sheet/resin. As described above, the moisture-proof layer may be a single layer of a resin coating layer, an aluminum moisture-proof tape, or an aluminum foil moisture-proof sheet, or may be a multilayer of two or more kinds, and the order of the multilayer is not particularly limited.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[ construction example of Heat insulating Structure ]

The following materials were used to construct a heat insulating structure as shown in fig. 1.

[ materials used ]

High rigidity material: "SE 40 FO" manufactured by Nisshinbo chemical Co., Ltd.; hard PUF, foaming agent: HFO, core density: about 40kg/m³And the size is as follows: 200mm, 1000mm, 30mm wide

Elastomeric materials: "baseect (registered trademark) G +", manufactured by BASF japan ltd; melamine resin foam

Butyl double-sided tape: thickness of 1.0mm and width of 30mm

Glass wool: 50mm in width and 200mm in height

Agricultural mulching film: perforated polyethylene film

Spray glue

Spray-blown polyurethane: "SH-450", manufactured by Nisshinbo chemical Co., Ltd.; hard PUF, foaming agent: HFO, core density: about 40kg/m³

Glass cloth: thickness of 0.22mm

Resin coating agent: sewyell (registered trademark), a polyurea resin available from Mitsui chemical Co., Ltd

Further, the core density of the hard PUF of the high-rigidity material and the jet foamed polyurethane is in accordance with JIS 7222: 2005 apparent core Density measurement method.

(example 1)

On an SUS steel plate 1 to be regarded as an outer wall of a low-temperature fluid tank, a flat high-rigidity material 2a cut out from a hard PUF block is cut into a slit at an end in a longitudinal direction, 4 pieces of the high-rigidity material are combined in a mortise-tenon shape as shown in fig. 2 to form an intersection, divided into lattice-shaped sections X of about 1m square, and adhered with a butyl double-sided tape.

In the section X, an agricultural mulching film is attached by spraying glue as the base layer 3.

On each side surface of the flat high-rigidity member 2a, glass wool was adhered as an elastic member 2b by using a spray adhesive, and an elastic spacer 2 made of a composite material of the high-rigidity member 2a and the elastic member 2b was formed.

Next, in the divisional area X, the sprayed foamed polyurethane 4a was filled up to the height (total thickness 200mm) of the elastic partition 2 at a height (thickness) of 50mm each time.

After covering the top surface of the outermost layer of the sprayed foam urethane 4a with a glass cloth as a mesh-shaped reinforcing layer 5, the sprayed foam urethane 4b was filled on the top surface of the mesh-shaped reinforcing layer 5 at a height (thickness) of 50mm each time until the total thickness reached 200mm, and the total thickness of the sprayed

foam urethane

4a and 4b was set to 400 mm.

Then, a moisture-proof layer 6 having a thickness of 3mm was formed on the spray-foamed polyurethane 4b using a resin coating agent of a polyurea resin, and a test piece of the heat insulating structure was prepared.

(Cooling test)

In the test piece of the heat insulating structure produced in example 1, a cooling test was performed in which the SUS steel plate 1 side was cooled in liquid nitrogen (about-196 ℃) for 96 hours (4 days). At the positions of points a and B in fig. 1, the change with time of the temperature of the sprayed foamed polyurethane in the vicinity of the mesh-like reinforcing layer 5 was measured with a thermocouple thermometer.

As a result, it was confirmed that the temperature was maintained at a stable state at a low temperature of-80 to-70 ℃ at the point A. The temperature difference from the outside air temperature (room temperature of about 25 ℃) at the point B is within ± 5 ℃. From these results, it was found that the heat insulating structure of the test article had good heat insulating properties.

After the cooling test was completed, the plate was left at room temperature (about 25 ℃ C.) for 48 hours and then sliced in the plane direction of the SUS steel plate 1 at a height position of 50mm from the surface of the SUS steel plate 1. The presence or absence of cracks in the heat insulating layer, i.e., the sprayed foamed polyurethane 4a was visually observed, and as a result, the occurrence of cracks was not confirmed. Further, no so-called cold spot was observed on the outermost surface of the heat insulating structure, in which ice particles were generated due to the occurrence of the crack or the like.

Description of the symbols

1 SUS Steel plate (outer wall of can)

2 elastic partition

2a high rigidity material

2b elastic material

3 base layer

4a, 4b spray foamed polyurethane (foam-in-place polyurethane)

5 mesh reinforcement layer

6 moisture barrier

X partition

10 guide member

20a front view

20b in side view.

Claims

1. A heat insulation structure of a low-temperature fluid tank, comprising: an elastic partition plate which is arranged outside the tank and divides the outer wall of the tank into a plurality of subareas; and a foam-in-place polyurethane disposed at least within the partition.

2. The heat insulating structure of a cryogenic fluid tank according to claim 1, wherein the elastic partition plate comprises an elastic material.

3. The heat insulating structure of a cryogenic fluid tank according to claim 2, wherein the elastic partition plate is made of a composite material including the elastic material and a material having higher rigidity than the elastic material.

4. The heat insulating structure of a tank for a low-temperature fluid according to claim 3, wherein the material having higher rigidity than the elastic material contains at least a rigid polyurethane foam.

5. The heat insulating structure of a low-temperature fluid tank according to any one of claims 2 to 4, wherein the elastic material contains at least one selected from glass wool, melamine foam, phenol foam, and flexible polyurethane foam.

6. The heat insulating structure of a low-temperature fluid tank according to any one of claims 1 to 5, wherein the foam-in-place polyurethane is formed by laminating a plurality of layers on an outer surface of the tank, and a mesh-like reinforcing layer is provided between at least one of the plurality of layers.

7. The heat insulating structure of a cryogenic fluid tank according to any one of claims 1 to 6, wherein the heat insulating structure of the cryogenic fluid tank comprises a base layer that is in contact with the tank outer surface.

8. The heat insulating structure of a cryogenic fluid tank according to any one of claims 1 to 7, wherein a moisture barrier layer comprising at least one selected from a resin coating layer, an aluminum foil moisture barrier sheet and an aluminum moisture barrier tape is provided on the outermost surface of the foam-in-place polyurethane.

9. The heat insulating structure of a low-temperature fluid tank according to any one of claims 1 to 8, wherein the elastic partition plate has a height of 50 to 300mm and a width of 10 to 200 mm.

10. A method for constructing a heat insulating structure of a low-temperature fluid tank, comprising: a step of arranging an elastic partition plate on the outer side of the tank to divide the outer wall of the tank into a plurality of subareas, and a step of filling and spraying foaming polyurethane at least in the subareas.