JP2023014489A - Low temperature liquid storage tank and method for producing the same - Google Patents

Abstract

To facilitate the coating work of an outer tank of a low temperature liquid storage tank.SOLUTION: A low temperature liquid storage tank 100 disclosed herein has an outer tank 30, on the inner surface of which a downward blow layer 12, a foamed resin layer 13, and a reinforcement layer 14 are laminated. The reinforcement layer 14 contains reinforcement fibers 16, with the reinforcement fibers 16 overlapping each other in vertical and horizontal directions on a random basis. The content of the reinforcement fibers 16 is higher at the foamed resin layer 13 side of the reinforcement layer 14 than at the inner tank 20 side.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a low-temperature liquid storage tank in which low-temperature liquid of 0° C. or lower is stored, and a manufacturing method thereof.

As a conventional low-temperature liquid storage tank, there is known a tank that includes an inner tank that stores the low-temperature liquid inside and an outer tank that covers the inner tank from the outside, and the inner surface of the outer tank is coated with a foamed resin layer. (See Patent Document 1, for example).

Patent No. 3044605 (paragraph [0002], Fig. 4)

The conventional cryogenic liquid storage tank described above has a configuration in which a reinforcing sheet is provided on the surface of the foamed resin layer via an adhesive layer. In this configuration, a step of cutting and flattening the surface of the foamed resin layer was required before applying the adhesive so that the reinforcing sheet would not be lifted and peeled off. In view of this, there is a demand for facilitating the coating operation of the outer tank of the cryogenic liquid storage tank.

The first aspect of the present invention, which has been made to solve the above problems, is an inner tank in which a low-temperature liquid of 0 ° C. or less is stored, an outer tank covering the outside thereof, and a foamed liquid coated on the inner surface of the outer tank. and a resin layer, the low-temperature liquid storage tank having a resin reinforcing layer containing chopped strands on the inner surface of the foamed resin layer.

According to the first aspect of the invention, the foamed resin layer is reinforced by the chopped strands instead of the reinforcing sheet. The coating work of the outer tank can be facilitated without the need for the step of

1 is a cutaway front view of a cryogenic liquid storage tank according to an embodiment of the present disclosure; FIG. Enlarged sectional view of the tank Cross section of relief layer Schematic diagram showing the flow of liquefied natural gas entering the diffusion layer made of low-density rigid urethane foam. A diagram showing the state of construction of the relaxation layer on the inner surface of the outer tank Diagram showing the flow of construction method of relaxation layer Diagram for explaining the second step

The cryogenic liquid reservoir 100 of the present disclosure will now be described with reference to FIGS. 1-4. As shown in FIG. 1, the cryogenic liquid storage tank 100 of this embodiment includes a hollow cylindrical tank portion 40 having an inner tank 20 and an outer tank 30, and a cylindrical liquid barrier surrounding the tank portion 40. 50. The tank part 40 stores the liquefied natural gas L inside the inner tank 20 . The capacity of the low-temperature liquid storage tank 100 is generally 140,000 to 230,000 kL, which is called a large one. The height is about 40m.

The inner tub 20 and the outer tub 30 are provided with ceiling portions 21 and 31, respectively, and have a structure in which the inside thereof is shut off from the outside. The ceiling portions 21 and 31 have a dome shape with a swollen central portion, and form a space filled with vaporized liquefied natural gas L. Both the inner tank 20 and the outer tank 30 are made of metal. For example, from the viewpoint of low temperature toughness, iron or steel is preferable. In particular, since the inner tank 20 is always exposed to extremely low temperatures, an alloy such as nickel having iron as a main component and having excellent low-temperature toughness is preferable.

The dike 50 is installed to prevent the diffusion of the liquefied natural gas L in the event of an accidental leakage of the liquefied natural gas L. In this embodiment, the inner surface of the dike 50 is superimposed on The dike 50 is made of prestressed concrete that is hard to crack.

In the tank part 40, the space formed between the inner tank 20 and the outer tank 30 is provided with a cold insulation layer 60 for keeping the liquefied natural gas L at about -160°C and reducing the vaporization of the liquefied natural gas L. It is The cold insulation layer 60 is composed of a ceiling cold insulation layer 61 , a side cold insulation layer 62 and a bottom cold insulation layer 63 .

Specifically, in the inner tank 20 and the outer tank 30, the space formed in the ceiling parts 21 and 31 and the space formed in the side parts 22 and 32 include the ceiling cold insulation layer 61 and the side cold insulation layer 61. The layer 62 is filled with granular perlite or the like having heat insulation performance. In addition, in the space formed in the bottoms 23 and 33 of the inner tank 20 and the outer tank 30, perlite concrete, lightweight cellular concrete, or the like having load-bearing performance and heat insulation performance is disposed as the bottom cold insulation layer 63. there is

In the cryogenic liquid storage tank 100, the inner surface 30S of the outer tank 30 is coated with the relaxation layer 10. As shown in FIG. The relaxation layer 10 is formed to prevent the thermal shock of the leaked liquefied natural gas L from being rapidly transmitted to the liquid barrier 50 .

As shown in FIG. 2, the relieving layer 10 includes a side relieving layer 10S that covers the entire inner surface 30S of the outer tub 30, and an annular bottom surface that covers the entire periphery of the inner bottom surface 30T of the outer tub 30. and a relaxation layer 10T. The bottom relaxation layer 10T also covers the peripheral edge of the bottom cold insulation layer 63 .

FIG. 3 shows the cross-sectional structure of the relaxation layer 10 of this embodiment. The relaxation layer 10 is formed by laminating an under-blown layer 12, foamed resin layers 13 (13A, 13B), and a reinforcing layer 14 on the inner surface (inner surface 30S and inner bottom surface 30T) of the outer tub 30. As shown in FIG.

The under-blown layer 12 and the foamed resin layer 13 are composed of rigid urethane foam formed by foaming and curing a urethane foam raw material. Rigid urethane foam has a relatively thin thickness and excellent heat insulation performance. Therefore, a rapid temperature change (thermal shock) caused by the cold heat of the liquefied natural gas L can be mitigated, and the liquid barrier 50 can be prevented from being subjected to the thermal shock.

The underblown layer 12 is a layer directly laminated on the inner surface of the outer tank 30 and serves as a primer for ensuring the adhesiveness of the foamed resin layer 13 . The thickness is preferably 0.1-5 mm.

The foamed resin layer 13 is laminated on the underblown layer 12 and protects the dike 50 by suppressing and alleviating the rapid transmission of cold heat from the liquefied natural gas L. Therefore, it is preferable that the foamed resin layer 13 has excellent heat insulating performance and compressive strength, and has a small thickness from the viewpoint of efficient use of space. Specifically, it preferably has a density of 40 to 80 kg/m ³ , a thermal conductivity of 0.040 W/mK or less, and a compressive strength of 360 kPa or more. Moreover, the thickness of the foamed resin layer 13 is preferably 40 mm or more and 60 mm or less. With this thickness, it is possible to suppress a local temperature drop in the outer tub 30 . Although the foamed resin layer 13 is composed of two layers (13A, 13B) in the present embodiment, it may be composed of one layer, or may be composed of three or more layers. The skin layer of the foamed resin layer 13 is a high-density urethane layer, and since the ratio of urethane resin increases compared to the core portion, the thermal conductivity increases and the heat insulation performance decreases. For this reason, it is preferable that the number of layers constituting the foamed resin layer 13 is small, and it is more preferable to constitute the foamed resin layer 13 with one or two layers.

The compressive strength required for the foamed resin layer 13 is determined by setting the height of the embankment to 40 m (23 10,000 kL low-temperature liquid storage tank), and calculated with a safety factor of 2.0 from "8.4.4 Thermal resistance relaxation material", it is about 360 KPa. Therefore, the compressive strength required for the foamed resin layer 13 is 360 KPa or more.

The foamed resin layer 13 of this embodiment has a density of 65 kg/m ³ , a thermal conductivity of 0.022 W/mK, a compressive strength of 520 KPa, and a thickness of 50 mm (two layers of 25 mm).

A reinforcing layer 14 is laminated on the surface of the foamed resin layer 13 . The reinforcing layer 14 is made of hard urethane foam and has a thickness of 5 to 20 mm.

As shown in FIG. 4, the reinforcing layer 14 contains reinforcing fibers 16 . The reinforcing fibers 16 are chopped strands of glass fibers of 10 to 50 mm (preferably 38 mm or more), and most of them are arranged inside the reinforcing layer 14 . The reinforcing fibers 16 may be carbon fibers, aramid fibers, or the like.

The reinforcing fibers 16 are randomly overlapped vertically and horizontally. A part of the reinforcing fibers 16 extends substantially parallel to the inner surface of the foamed resin layer 13, and the rest of the reinforcing fibers 16 is inclined with respect to the inner surface of the foamed resin layer 13. The average inclination angle with respect to the inner surface is 25° or less. In addition, the content of the reinforcing fibers 16 is higher on the foamed resin layer 13 side of the reinforcing layer 14 than on the inner tank 20 side.

Further, in this embodiment, the rigid urethane foam of the reinforcing layer 14 is composed of two layers (14A, 14B). The first reinforcing layer 14A on the foamed resin layer 13 side is thicker than the second reinforcing layer 14B on the inner tank 20 side, and the content of the reinforcing fibers 16 is higher in the first reinforcing layer 14A than in the second reinforcing layer 14A. It is higher than 14B. Most of the reinforcing fibers 16 contained in the second reinforcing layer 14B extend from the inside or surface of the first reinforcing layer 14A to the second reinforcing layer 14B. rare.

The expansion ratio of the hard urethane foam of the second reinforcing layer 14B is the same as that of the hard urethane foam of the resin foam layer 13, while the expansion ratio of the hard urethane foam of the first reinforcing layer 14A is the same as that of the hard urethane foam of the resin foam layer 13. It is smaller than the expansion ratio of the foam. This is because if the expansion ratio of the rigid urethane foam of the first reinforcing layer 14A containing the reinforcing fibers 16 is too large, the holding force of the reinforcing fibers 16 will not be sufficient. The hard urethane foam of the first reinforcing layer 14A has an expansion ratio of 1 to 10 times, a free expansion density of 120 to 1200 kg/m ³ , and a basis weight of 1.2 kg/m ² (=1200 kg/m ³ ×0.001 m). Above is preferable.

Next, a method for constructing the relaxation layer 10 will be described with reference to FIGS. The relaxation layer 10 is constructed in a state where the inner tank 20, the outer tank 30, and the dike 50 are almost completed, and before the granular perlite is filled between the side portions 22, 32 of the inner tank 20 and the outer tank 30. is performed on Therefore, as shown in FIG. 6, workers M, N, O, and P enter the narrow space between the side portion 22 of the inner tank 20 and the side portion 32 of the outer tank 30 to carry out construction. At this time, since the bottom cold insulation layer 63 is arranged on the outer tank 30 and the inner tank 20 is arranged thereon, the entrance is normally provided in the ceiling (not shown). The width of the side portion 22 of the inner bath 20 and the side portion 32 of the outer bath 30 is 1000 mm to 2000 mm, and the height is about 45 m.

Among the relief layers 10, the side relief layers 10S provided on the inner side surface 30S of the outer tank 30 are constructed, as shown in FIG. by person M, N or O. The gondola 70 is suspended along the inner side surface 30S of the outer tank 30 in the space K so as to be vertically movable and horizontally movable.

Construction of the relaxation layer 10 is performed for each of a plurality of construction areas W obtained by dividing the inner surface 30S and the inner bottom surface 30T of the outer tank 30 at predetermined intervals in the vertical direction. In constructing the side relief layer 10S, the workers M, N, or O who got into the gondola 70 sequentially construct the construction area W from the upper end portion or the lower end portion. When the construction of a certain construction area W is completed, it moves horizontally to the adjacent construction area W, and similarly construction is repeatedly performed from the upper end or the lower end. When the construction area W is constructed in order from the upper end or the lower end, an area that cannot be constructed from the gondola 70 is moved horizontally to the next construction area W without performing construction. Regarding the area of the side relief layer 10S that cannot be constructed from the gondola 70 and the bottom relief layer 10T, as shown in FIG. Worker P does. Alternatively, M, N, or O may get off the gondola 70 each time and work continuously.

FIG. 6 shows the construction flow of the relaxation layer 10 . As shown in the figure, in the construction of the relaxation layer 10, a first step S1 is first performed by an operator M. As shown in FIG. After that, the second step S2 is performed by the worker N so as to follow the worker M. Furthermore, after that, the third step S3 is performed by the worker O so as to follow the worker N.

In the first step S<b>1 , a urethane foam raw material is sprayed onto the inner surface of the outer tank 30 by a spray method, and foamed and cured to form the foamed resin layer 13 . At this time, before forming the foamed resin layer 13, the under-blown layer 12 is formed by the same spray method.

Specifically, in the first step S1, the worker M sprays the urethane foam raw material toward the inner surface of the outer tank 30 with the spray gun 90 that he carries to form the under-blown layer 12, and then sprays it again, A foamed resin layer 13 is formed to have a predetermined thickness. In the present embodiment, the two foamed resin layers 13A and 13B are formed by performing the spraying in two steps. This is because even if you try to form a predetermined thickness with a single spray, the sprayed urethane foam raw material will harden to some extent, and it will drip before it exhibits its shape-retaining power, resulting in a uniform thickness. This is because it becomes difficult to secure. In this case, after the first spraying is completed, the second spraying is carried out after the hardening progresses and the tackiness (stickiness) of the surface disappears. The outer foamed resin layer 13A and the inner foamed resin layer 13B are formed to have substantially the same thickness.

In this embodiment, the underblown layer 12 is formed by applying the same urethane foam raw material as the foamed resin layer 13 . Due to the presence of the underblown layer 12, the adhesion of the outer foamed resin layer 13A to the inner surface 30S of the outer tank 30 can be improved. In this case as well, after the under-blown layer 12 has been sprayed, it is sprayed after the hardening progresses and the tackiness of the surface disappears. When the foamed resin layer 13 is formed directly on the inner surface of the outer tank 30 without providing the under-blown layer 12, heat is taken away from the portion adhering to the inner surface of the outer tank 30 which is made of metal and has high thermal conductivity. In addition, there is a possibility that the foamed resin layer 13 may be peeled off from the outer tub 30 due to an insufficient degree of foaming or a decrease in adhesive strength between the outer tub 30 and the foamed resin layer 13 .

In the second step S2, the worker N sprays the urethane foam raw material and the reinforcing fibers onto the foamed resin layer 13 using a chopper-equipped spray gun 91 carried by the operator, thereby forming the first reinforcing layer of the reinforcing layer 14. 14A. As shown in FIG. 7, the chopper-equipped spray gun 91 of the second step S2 has a chopper 91B for supplying the reinforcing fibers 16 on the spray gun main body 91A for spraying the urethane foam raw material. The chopper 91B cuts a glass fiber wire to a predetermined length to form reinforcing fibers 16, and adds them to the misty urethane foam raw material sprayed from the spray gun main body 91A.

Thereby, the first reinforcing layer 14A containing the reinforcing fibers 16 is formed. Some of the reinforcing fibers 16 are arranged inside the first reinforcing layer 14A, some are arranged on the surface of the first reinforcing layer 14A, and some are arranged on the surface of the first reinforcing layer 14A. becomes protruding from

If the fiber length of the reinforcing fiber 16 is too long, the trajectory of the fiber ejected from the chopper 91B will not be stable, and there will be a portion where the urethane foam raw material does not adhere, and there is a risk that the fixation will be insufficient. If the length is too short, the overlap between the reinforcing fibers 16 becomes small, resulting in an insufficient reinforcing effect. Although it is conceivable to increase the spray amount of the short reinforcing fibers 16, it is conceivable that voids are likely to occur. For example, it is preferable to contain 75 to 250 g/m ² for 50 mm glass fiber, and 200 to 450 g/m ² for 10 mm glass fiber.

Moreover, the water content in the polyol mixture in the urethane foam raw material for the first reinforcing layer 14A is preferably 0.03 to 1.0 wt %. To improve liquid penetration, a foaming catalyst is added to the polyol mixture that promotes the reaction of water with isocyanate groups rather than the reaction of carbon-bonded hydroxyl groups with isocyanate groups. A low-viscosity liquid (foaming agent, plasticizer, flame retardant, etc.) may be added to the polyol mixture to lower the viscosity.

Moreover, the urethane foam raw material to be sprayed in the second step S2 is one that does not drip 60 seconds after it adheres to the inner surface of the foamed resin layer 13 . As a result, it is possible to prevent the reinforcing fibers 16 from running down due to dripping of the raw material of the urethane foam, thereby preventing occurrence of locations where the reinforcing fibers 16 do not exist.

In the third step S3, the worker O sprays a urethane foam raw material with a spray gun 90 carried by the worker O onto the first reinforcing layer 14A containing the reinforcing fibers 16 to form the second reinforcing layer 14B. In the third step S3, the reinforcing fibers 16 are not added to the urethane foam raw material. As a result, the reinforcing fibers 16 arranged on the surface of the first reinforcing layer 14A are covered with the second reinforcing layer 14B, and the second reinforcing layer 14B is formed between the reinforcing fibers 16 projecting from the surface of the first reinforcing layer 14A. of hard urethane foam enters.

The configuration of the relaxation layer 10 of the present embodiment and the construction method thereof have been described above. Next, the effects of the relaxation layer 10 and its construction method will be described.

When the liquefied natural gas L leaks from the inner tank 20 , thermal shock of the liquefied natural gas L is transmitted to the foamed resin layer 13 through the reinforcing layer 14 . At this time, since the reinforcing fibers 16 are overlapped with each other in the reinforcing layer 14 laminated on the foamed resin layer 13, the foamed resin layer 13 locally shrinks due to the thermal shock of the liquefied natural gas L, The occurrence of cracks is suppressed. Moreover, cracks in the reinforcement layer 14 itself are also prevented.

Further, the reinforcing layer 14 is formed by laminating the first reinforcing layer 14A by adding the reinforcing fiber 16 in the second step S2, and then laminating the second reinforcing layer 14B without adding the reinforcing fiber 16 in the third step S3. Since the first reinforcing layer 14A on the foamed resin layer 13 side has a higher content of the reinforcing fibers 16 than the second reinforcing layer 14B on the inner tank 20 side, cracks in the foamed resin layer 13 do not occur. more protected. Moreover, since the amount of the reinforcing fibers 16 exposed from the inner surface of the reinforcing layer 14 is reduced, the dropping of the reinforcing fibers 16 is prevented.

Further, when air enters between the reinforcing fibers 16 and voids are present in the reinforcing layer 14, the liquefied natural gas L enters the inside thereof and gives a thermal shock to the foamed resin layer 13. It is conceivable that L boils and the reinforcing layer 14 blows off, but after laminating the first reinforcing layer 14A, the urethane foam raw material to which the reinforcing fiber 16 is not added is sprayed in the third step S3. Therefore, it is possible to prevent the hard urethane foam from entering between the reinforcing fibers 16 and to prevent voids from entering the reinforcing layer 14.例文帳に追加

Moreover, according to the structure of this embodiment, workability|operativity can be improved rather than the structure which laminates|stacks a reinforcement sheet on the surface of the conventional foamed resin layer 13. FIG. Specifically, in the configuration in which the reinforcing sheet is laminated on the surface of the foamed resin layer 13, the reinforcing sheet is attached to the surface of the foamed resin layer 13 with an adhesive or the like after the first step S1. At this time, the reinforcing sheet may float or come off from the surface of the foamed resin layer 13 due to its rigidity. Therefore, a step of cutting and flattening the surface of the foamed resin layer 13 is required. This process must be performed manually for all the construction areas W, and requires a huge amount of man-hours and costs. Moreover, man-hours and costs for removing the dust are required. Furthermore, dust from cutting chips generated during cutting not only worsens the work environment, but also poses the risk of dust explosion. On the other hand, in the present embodiment, even if the foamed resin layer 13 has unevenness, the reinforcing fibers 16 are arranged according to the unevenness. can.

Further, since the purpose of the cutting process is to flatten the surface, it is necessary to perform the cutting process after the foam hardening of the foamed resin layer 13 progresses and sufficient strength is exhibited. If processing such as cutting or grounding is performed before sufficient strength is developed, there is a risk that the material may not be cut flat or may tear. As a guideline, it takes about 24 hours (1 day) until sufficient strength is developed, which requires an extra number of days, resulting in an increase in cost. On the other hand, in the present embodiment, the second step S2 can be performed after the hardening in the first step S1 has progressed and the tack on the surface has disappeared. This eliminates the need to wait for the foaming and curing of the foamed resin layer 13 in the first step S1. Therefore, the above problem does not occur, and workability can be improved.

Furthermore, when the reinforcing sheet is attached with an adhesive or the like, it is necessary to be careful not to twist or lift the reinforcing sheet. is performed by spraying, the work can be simplified and workability can be improved. Also, if the reinforcing fibers 16 are mixed in the urethane foam raw material in advance, there is a risk that the reinforcing fibers 16 will clog the spray port of the spray gun and prevent ejection. Since the reinforcing fiber 16 is added onto the atomized urethane foam raw material sprayed from the spray gun main body 91A, the spray gun is less likely to clog. In addition, since the reinforcing fibers 16 are discharged from the chopper 91B and added in a state of being lined up in the same posture, the reinforcing fibers 16 are added to the foamed resin layer 13 rather than the structure in which the reinforcing fibers 16 are mixed in the urethane foam raw material in advance. The orientation along the inner surface of the foamed resin layer 13 makes it easier to overlap (easily approach so-called two-dimensional randomness), and the occurrence of cracks in the foamed resin layer 13 is further prevented.

Further, since the first to third steps S1 to S3 are all performed by spraying, the process of forming the relaxation layer 10 can be easily automated.

[Other embodiments]
(1) In the above embodiment, the low-temperature liquid storage tank 100 stores liquefied natural gas L, but other low-temperature liquid such as liquefied propane gas may be used.

(2) In the above embodiment, the tank part 40 has the ceiling parts 21 and 31, but it may have a structure in which a lid is provided and the top is open.

(3) The reinforcing layer 14 may be made of a non-foaming thermosetting resin (for example, urethane resin or epoxy resin).

(4) The reinforcing fibers 16 may be mixed in advance with the resin liquid (urethane foam raw material in the above embodiment).

(5) After applying the resin liquid, the reinforcing fibers 16 may be adhered before the resin liquid is completely cured.

(6) The resin liquid may be applied with a brush or the like instead of being sprayed.

(7) After forming the reinforcing layer 14 containing the reinforcing fibers 16, instead of applying the resin liquid not containing the reinforcing fibers 16, before the reinforcing layer 14 is completely hardened, a roller (not shown) or the like is applied. The surface of the reinforcing layer 14 may be pressed by the . In this case, the reinforcing fibers 16 can be brought closer to a posture parallel to the inner surface of the foamed resin layer 13, the arrangement of the reinforcing fibers 16 becomes closer to two-dimensional random, and the extending direction of the reinforcing layer 14 (inside the foamed resin layer 13) direction parallel to the side) is increased. In addition, the air trapped between the reinforcing fibers 16 can be removed, thereby preventing voids from entering the reinforcing layer 14.例文帳に追加

<Appendix>
Hereinafter, the features of the group of inventions extracted from the above-described embodiments will be described while showing effects and the like as necessary. In the following description, for ease of understanding, configurations corresponding to the above-described embodiments are appropriately shown in parentheses or the like, but are not limited to the specific configurations shown in parentheses or the like.

[Feature A1]
A low-temperature liquid storage tank comprising an inner tank for storing a low-temperature liquid of 0° C. or less, an outer tank covering the outside thereof, and a foamed resin layer coated on the inner surface of the outer tank,
A low-temperature liquid storage tank having a resin reinforcement layer containing chopped strands on the inner surface of the foamed resin layer.

According to feature A1, since the foamed resin layer is reinforced by the chopped strands instead of the reinforcing sheet, even if the foamed resin layer has unevenness, the chopped strands are arranged according to the unevenness. It is not necessary, and the coating work of the outer tank can be facilitated.

[Feature A2]
The cryogenic liquid reservoir of feature A1, wherein the reinforcing layer comprises a foamed resin.

[Feature A3]
3. The low-temperature liquid storage tank according to feature A1 or 2, wherein the reinforcing layer on the foamed resin layer side has a higher content of the chopped strands than on the inner tank side.

According to feature A3, since the content of chopped strands is higher in the reinforcing layer on the foamed resin layer side, the foamed resin layer is effectively reinforced and is less likely to break. In addition, since the content of chopped strands on the inner tank side of the reinforcing layer is low, the chopped strands are less likely to fall off when the inner surface of the reinforcing layer is exposed.

[Feature A4]
The cryogenic liquid storage tank according to any one of features A1 to 3, wherein the foamed resin layer and the reinforcing layer contain urethane foam.

According to the feature A4, by including urethane foam in both the foamed resin layer and the reinforcing layer, the compatibility is improved, and the reinforcing layer is less likely to peel off from the foamed resin layer.

[Feature A5]
5. The low-temperature liquid storage tank according to any one of Features A1 to 4, wherein at least the resin on the foamed resin layer side of the reinforcing layer has a foaming ratio smaller than that of the foamed resin layer.

According to feature A5, the resin easily adheres to the chopped strands, and the strength of holding the chopped strands of the reinforcing layer increases.

[Feature A6]
The cryogenic liquid reservoir according to any one of features A1 to 5, wherein the reinforcing layer has a thickness of 5 to 20 mm.

[Feature A7]
Cryogenic liquid reservoir according to any one of features A1 to 6, wherein the chopped strands have a length of 10 to 50 mm.

[Feature A8]
8. The cryogenic liquid storage tank according to any one of features A1 to 7, wherein the average inclination angle of the chopped strands in the reinforcing layer with respect to the inner surface of the foamed resin layer is 25° or less.

According to feature A8, the chopped strands in the reinforcing layer are closer to two-dimensional random than three-dimensional random, and the strength in the extending direction of the reinforcing layer increases.

[Feature A9]
An inner tank in which a low-temperature liquid of 0°C or less is stored, an outer tank that covers the outside of the outer tank, and a foamed resin layer that is coated on the inner surface of the outer tank to suppress leakage of the low-temperature liquid and mitigate thermal shock. and a method for manufacturing a cryogenic liquid storage tank,
a first step of applying a raw material to the inner surface of the outer tank and foaming and curing to form the foamed resin layer;
and a second step of applying a resin liquid together with chopped strands to the inner surface of the foamed resin layer and curing the resin liquid to form a reinforcing layer.

[Feature A10]
In the second step, the resin liquid is sprayed toward the inner surface of the foamed resin layer, and the chopped strands are mixed in the droplets of the resin liquid that are sprayed and adhere to the inner surface of the foamed resin layer. A method of manufacturing a cryogenic liquid storage tank according to Feature A9.

According to the feature A9 and the feature A10, the work of the first step and the second step is made common, which facilitates automation.

[Feature A11]
11. The method of manufacturing a cryogenic liquid storage tank according to feature A9 or 10, wherein in the second step, as the resin liquid, a liquid that does not drip 60 seconds after adhering to the inner surface of the foamed resin layer is used.

[Feature A12]
The method for manufacturing a low-temperature liquid storage tank according to any one of features A9 to 11, wherein the resin liquid containing the chopped strands is applied and then the resin liquid not containing the chopped strands is applied in an overlapping manner.

According to feature A12, the chopped strands protruding from the reinforcing layer can be reduced, and the chopped strands are more fixed.

[Feature A13]
Manufacture of a cryogenic liquid storage tank according to any one of features A9 to 11, wherein the surface of the reinforcing layer is pressed after applying the resin liquid containing the chopped strands and before curing of the reinforcing layer is completed. Method.

According to feature A13, chopped strands protruding from the reinforcing layer can be reduced. In addition, the chopped strands can be made parallel to the inner surface of the foamed resin layer, and the chopped strands can be arranged two-dimensionally at random, increasing the strength of the reinforcing layer in the extending direction. In addition, when it is close to three-dimensional random, it is considered that the strength of the reinforcing layer in the plate thickness direction increases and becomes strong against the liquid pressure of the low-temperature liquid.

Although specific examples of the technology included in the claims are disclosed in the specification and drawings, the technology described in the claims is not limited to these specific examples. Various modifications and changes of the examples are included, and a part of specific examples is also included.

REFERENCE SIGNS LIST 10 relaxation layer 13 foamed resin layer 14 reinforcement layer 14A first reinforcement layer 14B second reinforcement layer 16 reinforcement fiber (chopped strand)
20 inner tank 30 outer tank 50 liquid barrier 90 spray gun 91 spray gun 91A spray gun main body 91B chopper 100 cryogenic liquid storage tank

Claims (13)

A low-temperature liquid storage tank comprising an inner tank for storing a low-temperature liquid of 0° C. or less, an outer tank covering the outside thereof, and a foamed resin layer coated on the inner surface of the outer tank,
A low-temperature liquid storage tank having a resin reinforcement layer containing chopped strands on the inner surface of the foamed resin layer. 2. The cryogenic liquid storage tank according to claim 1, wherein said reinforcing layer contains foamed resin. 3. The low-temperature liquid storage tank according to claim 1, wherein the reinforcing layer on the foamed resin layer side has a higher content of the chopped strands than on the inner tank side. 4. The low-temperature liquid storage tank according to any one of claims 1 to 3, wherein said foamed resin layer and said reinforcing layer contain urethane foam. 5. The low-temperature liquid storage tank according to any one of claims 1 to 4, wherein at least the resin on the foamed resin layer side of the reinforcing layer has a foaming ratio smaller than that of the foamed resin layer. The cryogenic liquid storage tank according to any one of claims 1 to 5, wherein the reinforcing layer has a thickness of 5 to 20 mm. The cryogenic liquid storage tank according to any one of claims 1 to 6, wherein the chopped strands have a length of 10 to 50 mm. 8. The cryogenic liquid storage tank according to any one of claims 1 to 7, wherein the chopped strands in the reinforcing layer have an average inclination angle of 25° or less with respect to the inner surface of the foamed resin layer. An inner tank in which a low-temperature liquid of 0°C or less is stored, an outer tank that covers the outside of the outer tank, and a foamed resin layer that is coated on the inner surface of the outer tank to suppress leakage of the low-temperature liquid and mitigate thermal shock. and a method for manufacturing a cryogenic liquid storage tank,
a first step of applying a raw material to the inner surface of the outer tank and foaming and curing to form the foamed resin layer;
and a second step of applying a resin liquid together with chopped strands to the inner surface of the foamed resin layer and curing the resin liquid to form a reinforcing layer. In the second step, the resin liquid is sprayed toward the inner surface of the foamed resin layer, and the chopped strands are mixed in the droplets of the resin liquid that are sprayed and adhere to the inner surface of the foamed resin layer. The method for manufacturing a cryogenic liquid storage tank according to claim 9. 11. The method for manufacturing a low-temperature liquid storage tank according to claim 9, wherein in said second step, as said resin liquid, a liquid that does not drip 60 seconds after adhering to the inner surface of said foamed resin layer is used. 12. The method for manufacturing a low-temperature liquid storage tank according to claim 9, wherein the resin liquid containing the chopped strands is applied and then the resin liquid not containing the chopped strands is applied in an overlapping manner. 12. The low-temperature liquid storage tank according to any one of claims 9 to 11, wherein the surface of the reinforcing layer is pressed after applying the resin liquid containing the chopped strands and before curing of the reinforcing layer is completed. manufacturing method.

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