Low temperature liquid storage tank and manufacturing method thereof

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

[Technical field]

[0001] The present disclosure relates to a cryogenic liquid storage tank for storing a cryogenic liquid at 0° C. or below, and a manufacturing method thereof. [Background technology]

[0002] As a conventional cryogenic liquid storage tank, the cryogenic liquid is stored inside wall And then wall Covering from the outside wall Equipped with wall In one embodiment, the inner surface of the cushion is coated with a foamed resin layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3044605 (paragraph

[0002] , Figure 4) Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned conventional cryogenic liquid storage tank is configured to have a reinforcing sheet on the surface of a foamed resin layer via an adhesive layer. In this configuration, a process of cutting and flattening the surface of the foamed resin layer before applying the adhesive is required to prevent the reinforcing sheet from floating and peeling off. In view of this, wall There is a demand for facilitating the coating operation of the above-mentioned components. [Means for solving the problem]

[0005] The first aspect of the present invention, which has been made to solve the above problems, is a liquid storage device for storing low-temperature liquid below 0°C. wall And the outer covering wall And the above wall and a foamed resin layer coated on the inner surface of the low-temperature liquid storage tank, wherein the inner surface of the foamed resin layer has a reinforcing layer made of a resin containing chopped strands. Effect of the Invention

[0006] According to the first aspect of the invention, the foamed resin layer is reinforced by chopped strands instead of a reinforcing sheet. Therefore, even if the foamed resin layer has irregularities, the chopped strands are arranged according to the irregularities, so that no cutting process or other process is required and the external appearance can be improved. wall This makes it easier to carry out the coating work. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cutaway front view of a cryogenic liquid tank according to an embodiment of the present disclosure. [Diagram 2] Enlarged cross-sectional view of the tank [Diagram 3] Cross-section of the relaxation layer [Figure 4] Schematic diagram showing the flow of liquefied natural gas entering the inside of a diffusion layer made of low-density rigid polyurethane foam. [Diagram 5] A diagram showing the construction of a relief layer on the inside surface of an exterior wall [Figure 6] A diagram showing the flow of construction method for the relief layer [Figure 7] FIG. 2 is a diagram for explaining the second step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a cryogenic liquid storage tank 100 according to the present disclosure will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, the cryogenic liquid storage tank 100 according to the present embodiment has an internal structure. wall 20 and outside wall The tank portion 40 is made of a hollow cylindrical tank section 40 having a tank 30 and a cylindrical liquid barrier 50 surrounding the tank portion 40. The tank portion 40 is made of a wall Liquefied natural gas L is stored inside the cryogenic liquid storage tank 20. The capacity of the cryogenic liquid storage tank 100, which is called large, is generally 140,000 to 230,000 kL, and in the case of a 230,000 kL cryogenic liquid storage tank 100, the diameter of the liquid retaining dike 50 is about 90 m and its height is about 40 m.

[0009] Inside wall20 and other wall The tanks 30 each have a ceiling portion 21, 31, and the inside of each tank is sealed off from the outside. The ceiling portions 21, 31 are dome-shaped with a bulging center, and form a space filled with vaporized liquefied natural gas L. wall 20 and other wall Both 30 are made of metal, and from the viewpoint of low temperature toughness, for example, iron or steel is preferable. wall Since 20 is constantly exposed to extremely low temperatures, it is preferable to use an alloy such as nickel whose main component is iron and has excellent low-temperature toughness.

[0010] The liquid barrier 50 is installed to prevent the diffusion of the liquefied natural gas L in the event of a leakage accident of the liquefied natural gas L. In this embodiment, the inner surface of the liquid barrier 50 is wall The dike 50 is made of prestressed concrete, which is resistant to cracking.

[0011] In the tank section 40, wall 20 and outside wall In the space formed between the containers 30, a cold insulation layer 60 is provided to keep the liquefied natural gas L at about -160°C and reduce the vaporization of the liquefied natural gas L. 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.

[0012] For details, wall 20 and other wall In the cooling system 30, the space formed in the ceiling portion 21, 31 and the space formed in the side portion 22, 32 are filled with granular perlite or the like having heat insulating properties as a ceiling portion cold insulation layer 61 and a side portion cold insulation layer 62. wall 20 and other wall In the space formed in the bottoms 23 and 33 of the cooling system 30, a bottom cold insulation layer 63 is provided, which is made of perlite concrete, lightweight aerated concrete, or the like having load-bearing and heat-insulating properties.

[0013] Now, in the low-temperature liquid storage tank 100, wallThe inner surface 30S of the dike 50 is coated with a mitigating layer 10. The mitigating layer 10 is formed to prevent the thermal shock of the leaked liquefied natural gas L from being transmitted to the dike 50 suddenly.

[0014] As shown in FIG. 2, the relaxation layer 10 is wall A side relief layer 10S covers the entire inner surface 30S of the inner surface 30, and an outer wall The inner bottom surface 30T of the heat exchanger 30 is covered with an annular bottom surface relaxing layer 10T that covers the entire periphery of the inner bottom surface 30T of the heat exchanger 30. The bottom surface relaxing layer 10T also covers the periphery of the bottom cold insulation layer 63.

[0015] FIG. 3 shows a cross-sectional structure of the relaxation layer 10 of the present embodiment. wall On the inner surface (inner side surface 30S and inner bottom surface 30T) of 30, an under-blowing layer 12, a foamed resin layer 13 (13A, 13B), and a reinforcing layer 14 are laminated.

[0016] The under-blow layer 12 and the foamed resin layer 13 are made of a rigid urethane foam formed by foaming and hardening a urethane foam raw material. The rigid urethane foam has a relatively thin thickness and excellent heat insulating properties. Therefore, it is possible to mitigate the sudden temperature change (thermal shock) caused by the cold heat of the liquefied natural gas L, and prevent the liquid retaining dike 50 from being subjected to the thermal shock.

[0017] The lower blowing layer 12 is wall This layer is laminated directly on the inner surface of the foamed resin layer 30 and serves as a primer to ensure the adhesiveness of the foamed resin layer 13. The thickness of this layer is preferably 0.1 to 5 mm.

[0018] The foamed resin layer 13 is laminated on the down-blowing layer 12, and protects the dike 50 by suppressing and mitigating the sudden transfer of heat and cold of the liquefied natural gas L. For this reason, the foamed resin layer 13 has excellent heat insulating properties and compressive strength, and is preferably thin from the viewpoint of efficient use of space. Specifically, the density is 40 to 80 kg / m 3The foamed resin layer 13 preferably has a thermal conductivity of 0.040 W / mK or less and a compressive strength of 360 kPa or more. The foamed resin layer 13 preferably has a thickness of 40 mm or more and 60 mm or less. wall 30 can be suppressed from localized temperature drops. In this embodiment, the foamed resin layer 13 is composed of two layers (13A, 13B), but it may be composed of one layer or 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 is higher than that of the core portion, the thermal conductivity is higher and the heat insulating performance is reduced. For this reason, it is preferable that the number of layers constituting the foamed resin layer 13 is small, and it is more preferable that the foamed resin layer 13 is composed of one or two layers.

[0019] The compressive strength required for the foamed resin layer 13 is calculated as approximately 360 KPa based on the Japan Gas Association's LNG aboveground storage tank guidelines, assuming a liquid retaining dike height of 40 m (assuming a 230,000 kL low-temperature liquid storage tank) and a safety factor of 2.0 based on the Japan Gas Association's guidelines, "9.5.2.2 Load calculation." Therefore, the compressive strength required for the foamed resin layer 13 is 360 KPa or more.

[0020] The foamed resin layer 13 of this embodiment has a density of 65 kg / m 3 , thermal conductivity: 0.022W / mK, compressive strength: 520KPa, thickness: 50mm (25mm for two layers).

[0021] A reinforcing layer 14 is laminated on the surface of the foamed resin layer 13. The reinforcing layer 14 is made of a hard urethane foam, and has a thickness of 5 to 20 mm.

[0022] 4, the reinforcing layer 14 contains reinforcing fibers 16. The reinforcing fibers 16 are chopped strands of glass fiber having a length of 10 to 50 mm (preferably 38 mm or more), and most of the reinforcing fibers are disposed inside the reinforcing layer 14. The reinforcing fibers 16 may be carbon fibers, aramid fibers, or the like.

[0023] The reinforcing fibers 16 are randomly overlapped in the vertical and horizontal directions. Some of the reinforcing fibers 16 extend substantially parallel to the inner surface of the foamed resin layer 13, while the rest are inclined to the inner surface of the foamed resin layer 13, with the average inclination angle of the reinforcing fibers 16 to the inner surface of the foamed resin layer 13 being 25° or less. The content of the reinforcing fibers 16 is such that the foamed resin layer 13 side of the reinforcing layer 14 is higher than the inner surface of the foamed resin layer 13. wall It is higher than the 20 side.

[0024] 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 wall 20, and the first reinforcing layer 14A has a higher content of reinforcing fibers 16 than the second reinforcing layer 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, and there is almost no reinforcing fiber 16 that is entirely disposed in the second reinforcing layer 14B.

[0025] The expansion ratio of the rigid urethane foam of the second reinforcing layer 14B is the same as that of the foamed resin layer 13, while the expansion ratio of the rigid urethane foam of the first reinforcing layer 14A is smaller than that of the foamed resin layer 13. 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 retention force of the reinforcing fibers 16 becomes insufficient. The rigid urethane foam of the first reinforcing layer 14A has an expansion ratio of 1 to 10 times and a free foam density of 120 to 1200 kg / m 3 , basis weight 1.2kg / m 2 (=1200kg / m 3 × 0.001 m) or more.

[0026] Next, a method for constructing the relaxing layer 10 will be described with reference to FIGS. wall 20, outside wall 30 and dike 50 are almost completed. wall 20 and other wallThis is done before the granular pearlite is filled between the sides 22, 32 of the 30. Therefore, as shown in FIG. wall 20 side 22 and outer wall Workers M, N, O, and P enter the narrow space between the side 32 of the bottom plate 30 and the bottom plate 32 to carry out construction. wall A bottom cold insulation layer 63 is disposed on top of the bottom cold insulation layer 30, and an inner wall 20 is installed, so people usually enter and exit through an entrance in the ceiling (not shown). wall 20 side 22 and outer wall The width of the side 32 of the bridge 30 is 1000mm to 2000mm, and the height is about 45mm.

[0027] Of the 10 mitigation layers, the outer wall The construction of the side mitigation layer 10S provided on the inner surface 30S of the 30 is carried out by a worker M, N or O who gets on a gondola 70 attached to a trolley beam installed on a ceiling (not shown), as shown in FIG. 5. The gondola 70 runs through the space K from the outside wall The support 30 is suspended along an inner surface 30S of the support 30 so as to be movable up and down and horizontally.

[0028] The construction of the relief layer 10 is wall The construction of the side relief layer 10S 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 side relief layer 10S at a predetermined interval in the vertical direction. In the construction of the side relief layer 10S, the worker M, N, or O who gets on the gondola 70 works the construction area W in order from the upper end or the lower end. When the construction of a certain construction area W is completed, the worker moves horizontally to the adjacent construction area W and repeats the construction from the upper end or the lower end in the same manner. When the construction of the construction area W is performed in order from the upper end or the lower end, the worker moves horizontally to the adjacent construction area W without working on the area that cannot be worked from the gondola 70. The above-mentioned areas of the side relief layer 10S that cannot be worked from the gondola 70 and the bottom relief layer 10T are performed by the worker P after the construction of the side relief layer 10S is completed or in parallel with the construction of the side relief layer 10S, as shown in FIG. 5. Alternatively, M, N, or O may get off the gondola 70 each time and work continuously.

[0029] Fig. 6 shows the flow of construction of the relieving layer 10. As shown in the figure, in the construction of the relieving layer 10, the first step S1 is first performed by worker M. Then, the second step S2 is performed by worker N following worker M. Furthermore, after that, the third step S3 is performed by worker O following worker N.

[0030] In the first process S1, the raw material for urethane foam is sprayed onto the outside. wall The resin is sprayed onto the inner surface of the substrate 30 and foamed and cured to form the foamed resin layer 13. Before the foamed resin layer 13 is formed, the under-blow layer 12 is formed by a similar spraying method.

[0031] In detail, in the first step S1, the worker M sprays the urethane foam raw material with a spray gun 90 carried by the worker M. wall 30 to form the under-blow layer 12, and then spray again to form the foamed resin layer 13 to a predetermined thickness. In this embodiment, spraying is performed twice to form two foamed resin layers 13A and 13B. This is because, even if a predetermined thickness is to be formed by one spraying, the foamed and cured urethane foam raw material sprayed will progress to a certain extent and drip before exerting its shape retention, making it difficult to ensure the predetermined thickness uniformly. In this case, after the first spraying is completed, the curing progresses and the tack (stickiness) of the surface disappears, and then the second spraying is performed. The outer foamed resin layer 13A and the inner foamed resin layer 13B are formed to have approximately the same thickness.

[0032] In this embodiment, the under-blowing layer 12 is formed by applying the same urethane foam raw material as the foamed resin layer 13. Due to the presence of the under-blowing layer 12, the outer periphery of the outer foamed resin layer 13A wall In this case, the spraying is performed after the underspray layer 12 is sprayed, the curing progresses, and the tackiness of the surface disappears. wall When the foamed resin layer 13 is formed directly on the inner surface of the heat sink 30, the heat sink 30 is made of metal and has high thermal conductivity. wallHeat is absorbed from the part attached to the inner surface of 30, causing the degree of foaming to be insufficient or wall The adhesive strength between the foamed resin layer 13 and the heat-resistant layer 30 may decrease, and the foamed resin layer 13 may be peeled off. wall There is a risk that it may peel off from 30.

[0033] In the second step S2, worker N sprays urethane foam raw material and reinforcing fibers onto the foamed resin layer 13 using a spray gun with a chopper 91 that he carries with him, forming a first reinforcing layer 14A of the reinforcing layer 14. As shown in Fig. 7, the spray gun with a chopper 91 in the second step S2 is provided with a chopper 91B that supplies reinforcing fibers 16 on top of a spray gun body 91A that sprays the urethane foam raw material. The chopper 91B cuts glass fiber wires to a predetermined length to form reinforcing fibers 16, which are then added to the mist of urethane foam raw material sprayed from the spray gun body 91A.

[0034] This forms the first reinforcing layer 14A containing the reinforcing fibers 16. Some of the reinforcing fibers 16 are disposed inside the first reinforcing layer 14A, another part is disposed on the surface of the first reinforcing layer 14A, and still another part protrudes from the surface of the first reinforcing layer 14A.

[0035] If the fiber length of the reinforcing fibers 16 is too long, the trajectory of the fibers ejected from the chopper 91B will be unstable, resulting in some areas where the urethane foam raw material does not adhere, and there is a risk of insufficient adhesion, whereas if the fiber length is too short, the overlap between the reinforcing fibers 16 will be small, resulting in insufficient reinforcing effect. It is possible to increase the amount of short reinforcing fibers 16 sprayed, but this is likely to cause voids. For example, for glass fibers of 50 mm, the preferred thickness is 75 to 250 g / m. 2 , 10mm glass fiber is 200~450g / m 2 , is preferably contained.

[0036] The moisture 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%. In order to improve the permeability of the liquid, a foaming catalyst that promotes the reaction between water and isocyanate groups rather than the reaction between hydroxyl groups bonded to carbon atoms and isocyanate groups is added to the polyol mixture. Note that the viscosity may be reduced by adding a low-viscosity liquid (foaming agent, plasticizer, flame retardant, etc.) to the polyol mixture.

[0037] The urethane foam raw material sprayed in the second step S2 is one that does not drip 60 seconds after it is attached to the inner surface of the foamed resin layer 13. This prevents the reinforcing fibers 16 from flowing down due to dripping of the urethane foam raw material, which would result in the creation of areas where the reinforcing fibers 16 are not present.

[0038] In the third step S3, the worker O sprays the urethane foam raw material onto the first reinforcing layer 14A containing the reinforcing fibers 16 using a spray gun 90 carried by the worker O 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 rigid urethane foam of the second reinforcing layer 14B enters between the reinforcing fibers 16 protruding from the surface of the first reinforcing layer 14A.

[0039] The configuration of the relaxing layer 10 and the construction method thereof according to the present embodiment have been described above. Next, the effects of the relaxing layer 10 and the construction method thereof will be described.

[0040] Inside wall If the liquefied natural gas L leaks from inside 20, the thermal shock of the liquefied natural gas L is transmitted to the foamed resin layer 13 via the reinforcing layer 14. At this time, since the reinforcing layer 14 laminated on the foamed resin layer 13 contains the reinforcing fibers 16 overlapping each other, the foamed resin layer 13 is prevented from locally shrinking due to the thermal shock of the liquefied natural gas L and causing cracks. In addition, the reinforcing layer 14 itself is prevented from cracking.

[0041] 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. The first reinforcing layer 14A on the foamed resin layer 13 side is formed by laminating the first reinforcing layer 14A by adding the reinforcing fiber 16 in the third step S3. wall Since the content of the reinforcing fibers 16 is higher than that of the second reinforcing layer 14B on the side 20, the occurrence of cracks in the foamed resin layer 13 is more effectively prevented. In addition, since less of the reinforcing fibers 16 are exposed from the inner surface of the reinforcing layer 14, the reinforcing fibers 16 are prevented from falling off.

[0042] Furthermore, if air gets between the reinforcing fibers 16 and voids form in the reinforcing layer 14, it is possible that liquefied natural gas L will get inside and cause a thermal shock to the foamed resin layer 13, or that the liquefied natural gas L will boil and blow away the reinforcing layer 14. However, after laminating the first reinforcing layer 14A, by spraying a urethane foam raw material to which no reinforcing fibers 16 have been added in the third step S3, it is possible to prevent the rigid urethane foam from getting between the reinforcing fibers 16 and causing voids in the reinforcing layer 14.

[0043] In addition, according to the configuration of this embodiment, the workability can be improved compared to the conventional configuration in which a reinforcing sheet is laminated on the surface of the foamed resin layer 13. Specifically, in the configuration in which a reinforcing sheet is laminated on the surface of the foamed resin layer 13, after the first step S1, the reinforcing sheet is attached to the surface of the foamed resin layer 13 with an adhesive or the like. At this time, the reinforcing sheet may float or peel off from the surface of the foamed resin layer 13 due to its rigidity. Therefore, a process of cutting the surface of the foamed resin layer 13 to make it flat is required. This process is performed manually for all the application areas W, which requires a huge amount of labor and cost. Moreover, labor and cost are required to remove this dust. Furthermore, not only does the dust from the cutting chips generated during cutting worsen the working environment, but there is also a risk of a dust explosion. In contrast, in this embodiment, even if the foamed resin layer 13 has unevenness, the reinforcing fibers 16 are arranged according to the unevenness, so that a process such as cutting is not required, and the workability can be improved.

[0044] In addition, since the cutting process is intended to flatten the surface, it is necessary to perform the cutting process after the foamed resin layer 13 has progressed in foaming and curing and has developed sufficient strength. If cutting or grinding is performed before sufficient strength is developed, there is a risk that the surface may not be cut flat or may tear. The estimated time required for sufficient strength to be developed is about 24 hours (one day), which requires additional days and increases costs. In contrast, in this embodiment, the next second process S2 can be performed after the curing of the first process S1 has progressed and the tack of the surface has disappeared. This eliminates the need to wait for the foamed resin layer 13 to foam and cure in the first process S1. Therefore, the above-mentioned problems do not occur, and workability can be improved.

[0045] Furthermore, when attaching the reinforcing sheet with an adhesive or the like, it is necessary to take care that the reinforcing sheet does not become twisted or lifted. In this embodiment, the reinforcing fibers 16 that reinforce the foamed resin layer 13 are fixed by spraying, so that the work is simplified and the workability can be improved. If the reinforcing fibers 16 are mixed in advance into the urethane foam raw material, there is a risk that the reinforcing fibers 16 will clog the spray nozzle of the spray gun and make it impossible to discharge. In this embodiment, however, the spray gun is less likely to be clogged because the reinforcing fibers 16 are added onto the atomized urethane foam raw material sprayed from the spray gun body 91A by the spray gun 91 with chopper. In addition, the reinforcing fibers 16 are discharged from the chopper 91B and added in a lined up state in the same position, so that the reinforcing fibers 16 are more likely to overlap in a position along the inner surface of the foamed resin layer 13 (approaching a so-called two-dimensional random pattern) than in a configuration in which the reinforcing fibers 16 are mixed in advance into the urethane foam raw material, and the occurrence of cracks in the foamed resin layer 13 is more likely to be prevented.

[0046] In addition, since the first to third steps S1 to S3 are all performed by spraying, the process of forming the relieving layer 10 can be easily automated.

[0047] [Other embodiments] (1) In the above embodiment, the cryogenic liquid storage tank 100 stores liquefied natural gas L. However, the cryogenic liquid storage tank 100 may store other cryogenic liquids, such as liquefied propane gas.

[0048] (2) In the above embodiment, the tank portion 40 includes the ceiling portions 21, 31. However, the tank portion 40 may include a lid and have an open top.

[0049] (3) The reinforcing layer 14 may be made of a non-foaming thermosetting resin (for example, a urethane resin or an epoxy resin).

[0050] (4) The reinforcing fibers 16 may be mixed in advance into the resin liquid (the urethane foam raw material in the above embodiment).

[0051] (5) After the resin liquid has been applied, the reinforcing fibers 16 may be attached before the resin liquid has completely hardened.

[0052] (6) The resin liquid may be applied with a brush or the like instead of being sprayed.

[0053] (7) After forming the reinforcing layer 14 containing the reinforcing fibers 16, instead of applying a resin liquid not containing the reinforcing fibers 16, the surface of the reinforcing layer 14 may be pressed with a roller (not shown) or the like before the hardening of the reinforcing layer 14 is completed. In this case, the reinforcing fibers 16 can be brought closer to a parallel posture with the inner surface of the foamed resin layer 13, the arrangement of the reinforcing fibers 16 approaches two-dimensional randomness, and the strength of the reinforcing layer 14 in the extension direction (the direction parallel to the inner surface of the foamed resin layer 13) is increased. In addition, air trapped between the reinforcing fibers 16 can be removed, preventing voids from being formed in the reinforcing layer 14.

[0054] <Additional Notes> The following describes the features of the inventions extracted from the above embodiments, while indicating, as necessary, their effects, etc. In the following, for ease of understanding, the corresponding configurations in the above embodiments are appropriately indicated in parentheses, but the present invention is not limited to the specific configurations indicated in parentheses.

[0055] [Feature A1] When low-temperature liquid below 0℃ is stored, wall And the outer covering wall And the above wall A foamed resin layer is coated on the inner surface of the low-temperature liquid storage tank, A low-temperature liquid storage tank having a reinforcing layer made of a resin containing chopped strands on the inner surface of the foamed resin layer.

[0056] According to the feature A1, the foamed resin layer is reinforced by chopped strands instead of a reinforcing sheet. Therefore, even if the foamed resin layer has irregularities, the chopped strands are arranged according to the irregularities. Therefore, no cutting process or other process is required, and the external wall This makes it easier to carry out the coating work.

[0057] [Feature A2] The cryogenic liquid storage tank according to Feature A1, wherein the reinforcing layer contains a foamed resin.

[0058] [Feature A3] The reinforcing layer is disposed on the side of the foamed resin layer. wall The low temperature liquid storage tank according to feature A1 or A2, wherein the content of the chopped strands is higher on the side than on the side.

[0059] According to the feature A3, the content of chopped strands is higher on the foamed resin layer side of the reinforcing layer, so that the foamed resin layer is effectively reinforced and is less likely to break. wall Since the chopped strand content is low on the side, when the inner surface of the reinforcing layer is exposed, the chopped strands are less likely to fall off.

[0060] [Feature A4] The low-temperature liquid storage tank according to any one of Features A1 to A3, wherein the foamed resin layer and the reinforcing layer contain urethane foam.

[0061] According to feature A4, by including urethane foam in both the foamed resin layer and the reinforcing layer, the affinity between them is improved, and the reinforcing layer is less likely to peel off from the foamed resin layer.

[0062] [Feature A5] A low-temperature liquid storage tank according to any one of Features A1 to A4, wherein at least the resin of the reinforcing layer on the side of the foamed resin layer has a smaller foaming ratio than the foamed resin layer.

[0063] According to the feature A5, the resin is easily attached to the chopped strands, and the holding force of the chopped strands in the reinforcing layer is increased.

[0064] [Feature A6] 6. The cryogenic liquid storage tank according to any one of Features A1 to A5, wherein the reinforcing layer has a thickness of 5 to 20 mm.

[0065] [Feature A7] The cryogenic liquid storage tank according to any one of Features A1 to A6, wherein the chopped strands have a length of 10 to 50 mm.

[0066] [Feature A8] A low-temperature liquid storage tank according to any one of Features A1 to A7, 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.

[0067] According to the feature A8, the chopped strands in the reinforcing layer become closer to two-dimensional randomness than to three-dimensional randomness, and the strength of the reinforcing layer in the extension direction is increased.

[0068] [Feature A9] When low-temperature liquid below 0℃ is stored, wall And the outer covering wall And the above wall and a foamed resin layer coated on the inner surface of the tank to prevent leakage of the cryogenic liquid and to reduce thermal shock, Other wall A first step of applying a raw material to the inner surface of the mold and foaming and curing the raw material to form the foamed resin layer; 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.

[0069] [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 into droplets of the resin liquid that have been sprayed and are adhering to the inner surface of the foamed resin layer.

[0070] According to features A9 and A10, the operations of the first step and the second step are standardized, which facilitates automation.

[0071] [Feature A11] A method for manufacturing a low-temperature liquid storage tank according to Feature A9 or 10, in which the second step uses a resin liquid that does not drip 60 seconds after being attached to the inner surface of the foamed resin layer.

[0072] [Feature A12] A method for manufacturing a low-temperature liquid storage tank according to any one of features A9 to A11, comprising applying the resin liquid containing the chopped strands and then applying the resin liquid not containing the chopped strands on top of the applied resin liquid.

[0073] According to the feature A12, the chopped strands protruding from the reinforcing layer can be reduced, and the chopped strands are more firmly fixed.

[0074] [Feature A13] A method for manufacturing a low-temperature liquid storage tank according to any one of features A9 to A11, in which after applying the resin liquid containing the chopped strands, the surface of the reinforcing layer is pressed before hardening of the reinforcing layer is completed.

[0075] According to feature A13, the chopped strands protruding from the reinforcing layer can be reduced. Furthermore, the chopped strands can be brought closer to being parallel to the inner surface of the foamed resin layer, and the arrangement of the chopped strands can be brought closer to two-dimensional randomness, thereby increasing the strength of the reinforcing layer in the extension direction. Note that when the arrangement is closer to three-dimensional randomness, the strength of the reinforcing layer in the plate thickness direction increases, and it is considered that the reinforcing layer becomes stronger against the liquid pressure of the low-temperature liquid.

[0076] In addition, although this specification and drawings disclose specific examples of the technology included in the scope of the claims, the technology described in the claims is not limited to these specific examples, but includes various modifications and variations of the specific examples, as well as parts of the specific examples taken alone. [Explanation of symbols]

[0077] 10 relaxation layer 13 Foamed resin layer 14 Reinforcement layer 14A First Reinforcement Layer 14B Second reinforcing layer 16 Reinforcing fiber (chopped strand) within 20 wall 30 outside wall 50 Liquid dike 90 Spray Gun 91 Spray Gun 91A Spray Gun Body 91B Chopper 100 Low temperature liquid storage tank

Claims

1. A low-temperature liquid storage tank having a metal double wall, The container is provided with a metal inner wall in which a low-temperature liquid having a temperature of 0° C. or less is stored, a metal outer wall covering the outer wall, and a foamed resin layer coated on the inner surface of the outer wall, A reinforcing layer made of a resin containing chopped strands is provided on an inner surface of the foamed resin layer, A low-temperature liquid storage tank, in which at least the resin of the reinforcing layer on the side of the foamed resin layer has a smaller foaming ratio than that of the foamed resin layer.

2. The cryogenic liquid storage tank according to claim 1 , wherein the reinforcing layer includes a foamed resin.

3. 3. The low-temperature liquid storage tank according to claim 1, wherein the reinforcing layer has a higher content of chopped strands on the side of the foamed resin layer than on the side of the inner wall.

4. 4. The cryogenic liquid storage tank according to claim 1, wherein the foamed resin layer and the reinforcing layer contain urethane foam.

5. A low-temperature liquid storage tank as described in any one of claims 1 to 4, wherein the thickness of the reinforcing layer is 5 to 20 mm.

6. A low-temperature liquid storage tank as described in any one of claims 1 to 5, wherein the length of the chopped strands is 10 to 50 mm.

7. A low-temperature liquid storage tank as described in any one of claims 1 to 6, wherein the average inclination angle of the chopped strands in the reinforcing layer relative to the inner surface of the foamed resin layer is 25° or less.

8. A method for manufacturing a low-temperature liquid storage tank having a metallic double wall including an inner metallic wall in which a low-temperature liquid below 0°C is stored and a metallic outer wall covering the inner wall, and a foamed resin layer coated on the inner surface of the outer wall to prevent leakage of the low-temperature liquid and to mitigate thermal shock, comprising: A first step of applying a raw material to an inner surface of the outer wall, and foaming and curing the raw material to form the foamed resin layer; 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 used is one that does not drip 60 seconds after being attached to the inner surface of the foamed resin layer.

9. A method for manufacturing a low-temperature liquid storage tank as described in claim 8, wherein in the second step, the resin liquid is sprayed toward the inner surface of the foamed resin layer, and the chopped strands are mixed into the droplets of the resin liquid that are sprayed and adhere to the inner surface of the foamed resin layer.

10. A method for manufacturing a low-temperature liquid storage tank as described in claim 8 or 9, comprising applying the resin liquid containing the chopped strands and then applying the resin liquid not containing the chopped strands on top of the applied resin liquid.

11. A method for manufacturing a low-temperature liquid storage tank as described in claim 8 or 9, wherein after applying the resin liquid containing the chopped strands, the surface of the reinforcing layer is pressed before hardening of the reinforcing layer is completed.

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