Liquefied gas tank

Abstract

This liquefied gas tank comprises: an inner tank which houses liquefied gas; an outer tank which surrounds the inner tank; and a tubular pipe tower which includes a barrel portion having the lower end thereof bonded to the bottom wall inside the inner tank, a head portion located above the outer tank, and a connecting portion penetrating through the inner tank and the outer tank and connecting the barrel portion and the head portion in the vertical direction, the pipe tower extending from the bottom wall of the inner tank in the vertical direction. The connecting portion of the pipe tower includes: a tube body that has an inner tank–bonding portion to which the top of the inner tank is bonded and an outer tank–bonding portion to which the top of the outer tank is bonded, and that extends in the vertical direction; and a first deformation-permitting portion that connects the tube body and the upper end of the barrel portion, and that elastically deforms to permit displacement of the barrel portion with respect to the tube body.

Description

[Technical Field]

[0001] The present disclosure relates to a multi-shell liquefied gas tank with a pipe tower. [Background technology]

[0002] Liquefied gas tanks that store low-temperature liquefied gases such as liquefied hydrogen and liquefied natural gas have been known. When such a liquefied gas tank is installed on a ship as a cargo tank, for example, a cylindrical pipe tower extending vertically from the interior of the liquefied gas tank is provided. The lower end of the pipe tower is connected to the bottom of the tank. The upper part of the pipe tower penetrates the tank and protrudes above it, and the upper wall of the pipe tower is connected to the tank. Inside the pipe tower, loading pipes, spray pipes, level gauges, electrical wiring, work ladders, etc. are arranged.

[0003] Liquefied gas tanks are subject to thermal contraction caused by the loading of liquefied gas, deformation due to the weight of the liquefied gas, and deformation (vibration) due to hull vibration. Pipe towers also deform for similar reasons, but there is a difference in the deformation of liquefied gas tanks and pipe towers. Therefore, as shown in Patent Document 1, in conventional liquefied gas tanks, the lower end of the pipe tower is connected to the tank bottom by a lower cylinder with a larger diameter than the pipe tower. The lower end of the side plate of the lower cylinder is connected to the tank bottom, and the upper plate of the lower cylinder is connected to the lower end of the pipe tower. The upper plate of the lower cylinder deforms in the vertical direction, absorbing the difference in deformation between the tank and the pipe tower and preventing high stress from occurring at the joint between the pipe tower and the tank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3938591 Summary of the Invention [Problem to be solved by the invention]

[0005] Some liquefied gas tanks have a multi-shell structure to improve thermal insulation. A multi-shell liquefied gas tank includes an inner tank that contains liquefied gas and an outer tank that surrounds the inner tank, with a thermal insulation layer formed between the inner and outer tanks. A pipe tower is also installed in such a multi-shell liquefied gas tank. However, liquefied gas tanks with a multi-shell structure tend to be larger, and because the pipe tower penetrates the inner and outer tanks and protrudes above the tank, the pipe tower is tall in the vertical direction and the weight of the entire pipe tower is heavy.

[0006] In conventional liquefied gas tanks, when installing a pipe tower, first the lower cylinder is fixed to the bottom wall of the inner tank, then the top plate of the lower cylinder is supported from the inside with a jack and the bottom wall of the inner tank that supports the jack is reinforced, and then the pipe tower is placed on the top plate of the lower cylinder and the lower cylinder is welded to the inner and outer tanks. As a result, the installation work of the liquefied gas tank is complicated in order to prevent the top plate of the lower cylinder from deflecting. Furthermore, in a multi-shell structure, the weight of the pipe tower acting on the lower cylinder is greater than in a single-shell structure, so a greater support force is required to prevent the top plate of the lower cylinder from deflecting.

[0007] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a liquefied gas tank with a multi-shell structure equipped with a pipe tower, which simplifies the installation process of the pipe tower. [Means for solving the problem]

[0008] In order to solve the above problems, a liquefied gas tank according to one aspect of the present disclosure comprises: an inner tank for storing liquefied gas; an outer tank surrounding the inner tank; a cylindrical pipe tower extending in the vertical direction from the bottom wall of the inner tank, the pipe tower having a body portion having a lower end joined to the bottom wall of the inner tank, a head portion positioned above the outer tank, and a connecting portion penetrating the inner tank and the outer tank to connect the body portion and the head portion in the vertical direction, The connection portion of the pipe tower comprises a cylindrical body extending in the vertical direction, having an inner tank joint portion to which the top of the inner tank is joined and an outer tank joint portion to which the top of the outer tank is joined, and a first deformation-permitting portion that connects the cylindrical body to the upper end of the body and allows displacement of the body relative to the cylindrical body by elastically deforming. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a liquefied gas tank having a multi-shell structure and equipped with a pipe tower, which simplifies the installation process of the pipe tower. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view of a liquefied gas tank according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a vertical cross-sectional view of a liquefied gas tank according to an embodiment, showing a modified example of the lower part of the pipe tower. [Figure 3] FIG. 3 is an enlarged vertical cross-sectional view of the upper part of the liquefied gas tank according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the configuration of the assembly. [Figure 5] FIG. 5 is a diagram illustrating the joining of the connecting portions. [Figure 6] FIG. 6 is a diagram illustrating the joining of the connecting portions. [Figure 7] FIG. 7 is a diagram illustrating a method for installing a pipe tower. [Figure 8] FIG. 8 is an enlarged vertical cross-sectional view of the upper part of the liquefied gas tank according to the embodiment, showing the inner tank and the pipe tower in a thermally shrunk state. [Figure 9] FIG. 9 is a vertical cross-sectional view of a liquefied gas tank according to the first modification. [Figure 10] FIG. 10 is a vertical cross-sectional view of a liquefied gas tank according to the first modification. [Figure 11] FIG. 11 is a vertical cross-sectional view of a liquefied gas tank according to the second modification. [Figure 12]FIG. 12 is an enlarged vertical cross-sectional view of the upper part of the liquefied gas tank according to the second modification. [Figure 13] FIG. 13 is an enlarged vertical cross-sectional view of the upper part of the liquefied gas tank according to Modification 2, showing the state in which the inner tank and the pipe tower have been thermally shrunk. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a liquefied gas tank 1 according to one embodiment of the present disclosure. The liquefied gas tank 1 shown in FIG. 1 is a cryogenic container that stores low-temperature liquefied gas such as liquefied hydrogen or liquefied natural gas. The liquefied gas tank 1 is supported on a base via a skirt. The base is, for example, the hull of a liquefied gas carrier. However, the liquefied gas tank 1 to which the present disclosure is applied is not limited to a cargo tank mounted on a ship, and may be any cryogenic container in which a pipe tower is disposed within the tank.

[0012] The liquefied gas tank 1 is a spherical tank. However, the liquefied gas tank 1 is not limited to a spherical tank, and may be a deformed spherical tank having a prolate ellipsoid shape, a stretch tank having upper and lower hemispherical shapes with a cylindrical section in between, or a rectangular tank having a rectangular parallelepiped shape. The liquefied gas tank 1 includes an inner tank 31 that stores liquefied gas, and an outer tank 32 that surrounds the inner tank 31. The walls of the inner tank 31 and the outer tank 32 are spaced apart, and a heat insulating layer 33 is formed between the inner tank 31 and the outer tank 32. The heat insulating layer 33 may be filled with a heat insulating material, or may be a vacuum heat insulating layer.

[0013] A pipe tower 4 extending vertically is provided in approximately the center of the liquefied gas tank 1. Inside this pipe tower 4, there are arranged a loading pipe for loading or discharging liquefied gas into the inner tank 31, and a spray pipe through which liquefied gas passes to be extracted from the inner tank 31 in order to pre-cool the inner tank 31. The loading pipe and spray pipe are suspended from the top of the pipe tower 4, and a loading pump is provided at the lower end of the loading pipe within the pipe tower 4, and a spray pump is provided at the lower end of the spray pipe. The pipe tower 4 is also provided with a liquid level gauge, electrical wiring, etc. Furthermore, inside the pipe tower 4, there is provided a ladder to allow workers to enter the liquefied gas tank 1 from the top of the pipe tower 4.

[0014] The pipe tower 4 has a body 41, a head 42, and a connection 44. The connection 44 is disposed between the body 41 and the head 42 in the vertical direction, and connects the body 41 and the head 42.

[0015] The body 41 is a cylindrical body extending in the vertical direction. The lower end of the body 41 is joined to the bottom wall of the inner tank 31 inside the inner tank 31. The outer diameter of the body 41 is approximately constant in the vertical direction. However, as shown in FIG. 2, the body 41 may have a truncated cone integrally connected to the lower part of the cylindrical body. The lower end of the body 41 is rigidly joined to the inner tank 31, and the lower part of the body 41 does not have a deformation-tolerant part that actively allows deformation, so the lower part of the body 41 can well support the pipe tower 4, which is a heavy object.

[0016] The head 42 is a cylindrical body having a dome-shaped closed top. The head 42 is located above the outer tank 32. The head 42 is provided with through-holes for pulling out the piping and wiring that has passed through the pipe tower 4 to the outside, as well as manholes for work.

[0017] The connecting portion 44 is cylindrical, and the interior of the connecting portion 44 is in communication with the interiors of the body portion 41 and the head portion 42. The connecting portion 44 according to this embodiment is cylindrical with its axial direction extending in the vertical direction, but the connecting portion 44 may also be in the form of a rectangular or elliptical cylinder. FIG. 3 is an enlarged vertical cross-sectional view of the upper portion of the liquefied gas tank 1 according to this embodiment. As shown in FIG. 3, the connecting portion 44 has a cylindrical body 441 and a lower annular plate 442. The cylindrical body 441 is a tube that extends in the vertical direction, and the upper end of the cylindrical body 441 is joined to the lower end of the head portion 42. The cylindrical body 441 and the head portion 42 may be continuous. Alternatively, the cylindrical body 441 and the head portion 42 may be integrally formed.

[0018] The lower end of the cylindrical body 441 is joined to the outer edge of the lower annular plate 442. The lower annular plate 442 is an annular flat plate having a surface substantially perpendicular to the vertical direction. The lower annular plate 442 may be a truncated cone (e.g., a truncated cone whose inner edge is higher than the outer edge) tilted in a direction that cancels out elastic deformation. The shape of the outer edge of the lower annular plate 442 is substantially the same as the outer shape of the cylindrical body 441. An opening is formed in the approximate center of the lower annular plate 442, and the shape of the inner edge of the opening is substantially the same as the outer shape of the body portion 41. The inner edge of the lower annular plate 442 is joined to the upper end of the body portion 41. The lower annular plate 442 is flexible, and elastic deformation of the lower annular plate 442 allows the inner edge of the lower annular plate 442 to be displaced in the vertical direction relative to the outer edge of the lower annular plate 442. As such, the lower annular plate 442 of the connecting portion 44 is a first deformation-permitting portion A1 that actively permits deformation in the vertical direction.

[0019] The cylindrical body 441 of the connection part 44 has an inner tank joint part 48 to which the top of the inner tank 31 is joined, and an outer tank joint part 49 to which the top of the outer tank 32 is joined. The inner tank 31 has a top opening through which the cylindrical body 441 is inserted, and the inner edge of the top opening is airtightly joined to the cylindrical body 441. Similarly, the outer tank 32 has a top opening through which the cylindrical body 441 is inserted, and the inner edge of the top opening is airtightly joined to the cylindrical body 441. The lower annular plate 442 of the connection part 44 and at least a portion of the cylindrical body 441 are located inside the inner tank 31.

[0020] In the pipe tower 4 configured as described above, the outer diameter D2 of the head 42 is substantially the same as or larger than the outer diameter D1 of the trunk 41. Furthermore, the outer diameter D4 of the connecting portion 44 (i.e., the outer diameter of the cylindrical body 441) is larger than the outer diameter D1 of the trunk 41 and is also the same as or larger than the outer diameter D2 of the head 42. Note that "substantially the same" here includes cases where the two values ​​(outer diameters) are exactly the same, and cases where the difference between one of the two values ​​is approximately 10% or less of the other value, and where there is a difference between the two values ​​but the relationship between them does not change significantly even if they are considered to be the same.

[0021] In the liquefied gas tank 1 illustrated in Figure 3, the outer diameter D4 of the connecting portion 44 is larger than the outer diameter D1 of the body portion 41, and the outer diameter D4 of the connecting portion 44 and the outer diameter D2 of the head portion 42 are substantially the same [outer diameter D1 of the body portion 41 < outer diameter D4 of the connecting portion 44 ≒ outer diameter D2 of the head portion 42].

[0022] Here, a method for installing the pipe tower 4 of the liquefied gas tank 1 according to this embodiment will be described with reference to Figures 4 to 7. Figure 4 is a diagram for explaining the configuration of the assembly 40, Figures 5 and 6 are diagrams for explaining the connection of the connection part 44, and Figure 7 is a diagram for explaining the installation method of the pipe tower 4.

[0023] 4, before installing the pipe tower 4 on the inner tank 31 and the outer tank 32, an assembly 40 is fabricated in which the upper portion 411 of the body 41, the head 42, the connecting portion 44, the top opening peripheral portion 311 of the inner tank 31, and the top opening peripheral portion 321 of the outer tank 32 are integrally joined together. The assembly 40 may be fabricated in a factory rather than on site.

[0024] As shown in Fig. 5, the fitting (interface) between the cylindrical body 441 and the lower annular plate 442 of the connecting portion 44 may be such that the upper surface of the lower annular plate 442 is joined to the end surface of the cylindrical body 441. Furthermore, the fitting between the upper portion 411 of the trunk portion 41 and the lower annular plate 442 may be such that the lower surface of the lower annular plate 442 is joined to the end surface of the upper portion 411 of the trunk portion 41. Alternatively, as shown in Fig. 6, the fitting between the cylindrical body 441 and the lower annular plate 442 of the connecting portion 44 may be such that the circumferential surface of the lower annular plate 442 is joined to the inner wall of the cylindrical body 441. Furthermore, the fitting between the upper portion 411 of the trunk portion 41 and the lower annular plate 442 may be such that the end surface of the lower annular plate 442 is joined to the outer wall of the trunk portion 41.

[0025] As shown in Fig. 7, when installing the pipe tower 4 in the inner tank 31 and the outer tank 32, first, the lower portion 412 of the body 41 of the pipe tower 4 is carried into the inner tank 31, and the lower end of the lower portion 412 of the body 41 is rigidly joined to the bottom wall of the inner tank 31. Next, the assembly 40 is carried in and positioned so that the upper portion 411 and the lower portion 412 of the body 41 are butted against each other. Finally, the upper portion 411 and the lower portion 412 of the body 41 are joined, the main body of the inner tank 31 is joined to the top opening peripheral portion 311, and the main body of the outer tank 32 is joined to the top opening peripheral portion 321.

[0026] In the above-described pipe tower 4 installation method, the assembly 40 includes the lower annular plate 442, which is the first deformation-permissive portion A1. The load acting on the lower annular plate 442 in the assembly 40 state is derived from the weight of the connection portion 44, the body portion 41, the top opening periphery 311 of the inner tank 31, and the top opening periphery 321 of the outer tank 32. Therefore, the degree of deformation (deflection) of the lower annular plate 442 due to the assembly 40's own weight is significantly smaller than the degree of deformation of the plate material provided at the bottom of the pipe tower 4 to support the entire load of the pipe tower 4, as in the conventional method. Therefore, when joining the cylindrical body 441 and the head portion 42 to the lower annular plate 442, the process of supporting the lower annular plate 442 with jacks to prevent deflection can be omitted. This pipe tower 4 installation method reduces the number of joining work locations on-site compared to conventional methods and simplifies the work. This is expected to improve the workability of the pipe tower 4 and shorten the installation time.

[0027] FIG. 8 is an enlarged vertical cross-sectional view of the upper portion of the liquefied gas tank 1 according to the embodiment, showing the state in which the inner tank 31 and the pipe tower 4 have thermally shrunk. As shown in FIG. 8, when low-temperature liquefied gas is stored in the inner tank 31 of the liquefied gas tank 1, the inner tank 31 and the pipe tower 4 thermally shrink. Because temperature distribution occurs in the inner tank 31 and the pipe tower 4, the degree of thermal shrinkage is not uniform even if they are made of the same material. When the inner tank 31 and the pipe tower 4 have different amounts of vertical shrinkage, the lower annular plate 442, which is the first deformation-permitting portion A1 of the pipe tower 4, elastically deforms in the vertical direction, allowing the inner tank 31 to be displaced relative to the pipe tower 4 in the vertical direction, thereby preventing high stress from occurring at the joint between the pipe tower 4 and the inner tank 31. In the first deformation-permitting portion A1, the lower annular plate 442 actively deforms, but the cylindrical body 441 also deforms somewhat in response to the deformation of the lower annular plate 442. In the above, we have explained a case where a relative displacement occurs between the inner tank 31 and the pipe tower 4 due to a temperature difference between the inner tank 31 and the pipe tower 4 caused by the cold heat of the liquefied gas contained in the inner tank 31, but a similar relative displacement can also occur due to pressure or the weight of the liquid being applied to the inner tank 31 and the pipe tower 4. In this case, too, the relative displacement can be absorbed by deformation of the first deformable portion A1, as described above.

[0028] Next, a modified example of the above embodiment will be described. In the description of the modified example, the same or similar components as those in the above embodiment will be denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0029] [Variation 1] Fig. 9 is a vertical cross-sectional view of a liquefied gas tank 1A according to Modification 1 of the embodiment. As shown in Fig. 9, the liquefied gas tank 1A according to Modification 1 differs from the liquefied gas tank 1 according to the embodiment in that the outer diameter D4 of the connection portion 44 of the pipe tower 4 is larger than the outer diameter D2 of the head portion 42.

[0030] In the pipe tower 4 of the liquefied gas tank 1A according to the first modification, the outer diameter D1 of the body 41 and the outer diameter D2 of the head 42 are substantially the same, and the outer diameter D4 of the connecting portion 44 is larger than the outer diameter D1 of the body 41 [outer diameter D1 of the body 41 ≈ outer diameter D2 of the head 42 < outer diameter D4 of the connecting portion 44]. In this way, the outer diameter D4 of the connecting portion 44 is not restricted by the outer diameter D2 of the head 42 and may be larger than D2 of the head 42. The larger the outer diameter D4 of the connecting portion 44, the larger and easier it is for the connecting portion 44 to deform in the vertical direction.

[0031] The connection portion 44 of the pipe tower 4 of the liquefied gas tank 1A according to the first modification has a cylindrical body 441, a lower annular plate 442, and an upper annular plate 443. The upper annular plate 443 is an annular flat plate having a surface that is approximately perpendicular to the up-down direction. The shape of the outer edge of the upper annular plate 443 is substantially the same as the outer shape of the cylindrical body 441. An opening is formed in approximately the center of the upper annular plate 443, and the shape of the inner edge of this opening is approximately the same as the outer shape of the lower end of the head 42. The inner edge of the upper annular plate 443 is joined to the lower end of the head 42.

[0032] The inner tank 31 and the outer tank 32 are joined to the cylindrical body 441 of the connecting part 44, but when the outer tank 32 is joined to the upper end of the cylindrical body 441 as shown in Figure 10, the upper annular plate 443 of the connecting part 44 may be formed with a curved surface that smoothly continues with the outer tank 32.

[0033] [Variation 2] Fig. 11 is a vertical cross-sectional view of a liquefied gas tank 1B according to Modification 2 of the embodiment. As shown in Fig. 11, the liquefied gas tank 1B according to Modification 2 differs from the liquefied gas tank 1 according to the embodiment in that the connection portion 44 of the pipe tower 4 also has a deformation-permitting portion (second deformation-permitting portion A2) between the inner tank 31 and the outer tank 32.

[0034] FIG. 12 is an enlarged vertical cross-sectional view of the upper portion of a liquefied gas tank 1B according to Modification 2. As shown in FIG. 12, in the liquefied gas tank 1B according to Modification 2, the cylindrical body 441 of the connection portion 44 of the pipe tower 4 has at least one second deformable portion A2 between the inner tank joint 48 and the outer tank joint 49. The second deformable portion A2 includes an annular plate having a surface substantially perpendicular to the vertical direction. Instead of the annular plate, a truncated cone inclined in a direction that cancels out elastic deformation may be used. In the liquefied gas tank 1B illustrated in FIG. 12, the cylindrical body 441 of the connection portion 44 of the pipe tower 4 has a circumferentially continuous groove 45 between the inner tank joint 48 and the outer tank joint 49. This groove 45 is formed by a pair of annular plates (an upper annular plate 451 and a lower annular plate 452) facing each other in the vertical direction and a short cylindrical body 453. The member forming the groove 45 functions as the second deformable portion A2. The outer diameter of the short cylinder 453 inserted between the inner tank joint 48 and the outer tank joint 49 in the cylinder 441 is smaller than the outer diameter of the cylinder 441 (i.e., the outer diameter of the connection part 44). The outer edge of the upper annular plate 451 is joined to the cylinder 441, and the inner edge of the upper annular plate 451 is joined to the upper end of the short cylinder 453. The outer edge of the lower annular plate 452 is joined to the cylinder 441, and the inner edge of the lower annular plate 452 is Short cylinder 453 It is joined to the bottom end.

[0035] The outer tank 32 has a rising portion 322 that rises upward from the top opening. This rising portion 322 is joined to the connecting portion 44. The rising portion 322 may be joined to the head portion 42 at the connection portion between the connecting portion 44 and the head portion 42. In this way, a second deformation-permitting portion A2 including an upper annular plate 451 and a lower annular plate 452 is provided between the joint portion of the inner tank 31 and the joint portion of the outer tank 32 at the connecting portion 44. The inside of the recessed groove 45 forms a space that is continuous with the space between the inner tank 31 and the outer tank 32, and this space can be used for piping and wiring.

[0036] In the liquefied gas tank 1B according to the second modification, when low-temperature liquefied gas is stored in the inner tank 31, the inner tank 31 and the pipe tower 4 undergo thermal contraction. As shown in Fig. 13, the lower annular plate 442 of the connecting portion 44 of the pipe tower 4 elastically deforms in the vertical direction, thereby allowing the inner tank 31 to be displaced vertically relative to the pipe tower 4, and preventing high stress from occurring at the joint between the pipe tower 4 and the inner tank 31. Furthermore, the second deformable portion A2 including the upper annular plate 451 and the lower annular plate 452 elastically deforms in the vertical direction, thereby allowing the pipe tower 4 to be displaced vertically relative to the outer tank 32 and also allowing the top of the inner tank 31 to be displaced vertically relative to the top of the outer tank 32, and preventing high stress from occurring at the joint between the pipe tower 4 and the inner tank 31 and the outer tank 32. In the second deformation-permitting portion A2, the upper annular plate 451 and the lower annular plate 452 actively deform, but the deformation of the upper annular plate 451 and the lower annular plate 452 also causes some deformation of the short cylinder 453 and the cylinder 441. In the above, a case has been described in which a temperature difference occurs between the inner tank 31 and the pipe tower 4 due to the cold heat of the liquefied gas contained in the inner tank 31, causing relative displacement between the inner tank 31 and the pipe tower 4, and thus causing relative displacement between the outer tank 32 and the pipe tower 4. However, similar relative displacement can also occur when pressure or the weight of the liquid is applied to the inner tank 31 and the pipe tower 4. In this case, the relative displacement can be absorbed by the deformation of the first deformation-permitting portion A1 and the second deformation-permitting portion A2, as described above.

[0037] The liquefied gas tank 1B according to the second modification is a double-shelled tank having an inner tank 31 and an outer tank 32, but the pipe tower 4 and the tanks may be joined in a similar manner in a triple- or more-shelled tank. Specifically, in the case of a multi-shelled tank having at least one intermediate tank between the inner tank 31 and the outer tank 32, a deformation-permitting portion is provided in the pipe tower 4 between the joint of the inner tank 31 and the joint of the intermediate tank immediately outside the inner tank 31, and a deformation-permitting portion is provided in the pipe tower 4 between the joint of the intermediate tank and the joint of the outer tank 32 and / or between the joints of the intermediate layers.

[0038] [Summary] The liquefied gas tanks 1, 1A, and 1B according to the first item of the present disclosure are: an inner tank 31 for containing liquefied gas; an outer tank 32 surrounding the inner tank 31; The pipe tower 4 has a body 41 having a lower end joined to the bottom wall of the inner tank 31, a head 42 positioned above the outer tank 32, and a connecting part 44 connecting the body 41 and the head 42 in the vertical direction, and is cylindrical and extends from the bottom wall of the inner tank 31 through the inner tank 31 and the outer tank 32 in the vertical direction. The connection portion 44 of the pipe tower 4 has a cylindrical body 441 extending in the vertical direction, which has an inner tank joint portion 48 to which the top of the inner tank 31 is joined and an outer tank joint portion 49 to which the top of the outer tank 32 is joined, and a first deformation-permitting portion A1 that connects the cylindrical body 441 to the upper end of the body portion 41 and allows vertical displacement of the upper end of the body portion 41 relative to the cylindrical body 441 by elastically deforming.

[0039] The liquefied gas tank 1, 1A, 1B relating to the second item of the present disclosure is the liquefied gas tank 1, 1A, 1B relating to the first item, wherein the first deformation-permitting portion A1 is an annular plate (lower annular plate 442) having an outer edge joined to the lower end of the cylindrical body 441 and an inner edge joined to the upper end of the trunk portion 41.

[0040] In the liquefied gas tanks 1, 1A, 1B according to the first and second items above, a vertical relative displacement of the pipe tower 4 with respect to the inner tank 31 may occur. Such a relative displacement may occur, for example, due to thermal contraction of the inner tank 31 and the pipe tower 4 when low-temperature liquefied gas is stored in the inner tank 31 of the liquefied gas tank 1. Here, the first deformation-permitting portion A1 (i.e., the lower annular plate 442) of the pipe tower 4 elastically deforms, thereby permitting a vertical relative displacement of the pipe tower 4 with respect to the inner tank 31, and preventing high stress from occurring at the joint between the inner tank 31 and the pipe tower 4.

[0041] Furthermore, since the first deformable portion A1 (i.e., the lower annular plate 442) of the pipe tower 4 does not support the weight of the body 41, the degree of deformation of the first deformable portion A1 due to the weight of the pipe tower 4 is sufficiently small compared to the degree of deformation of a plate material that is conventionally provided at the bottom of the pipe tower 4 and supports the entire load of the pipe tower 4. Therefore, during the installation process of the pipe tower 4, it is possible to omit measures to support the first deformable portion A1 so as not to deform. In this way, according to the present disclosure, it is possible to provide a liquefied gas tank 1, 1A, 1B with a multi-shell structure that is equipped with a pipe tower 4 and that realizes a simplified installation process of the pipe tower 4.

[0042] The liquefied gas tank 1, 1A, 1B relating to the third item of the present disclosure is the liquefied gas tank 1, 1A, 1B relating to the second item, in which the upper surface of the annular plate 442 is joined to the end surface of the cylindrical body 441, and the lower surface of the annular plate 442 is joined to the end surface of the trunk portion 41.

[0043] According to the above-described liquefied gas tanks 1, 1A, and 1B, welding distortion can be reduced and excessive stress can be prevented by selecting an appropriate joint between the annular plate 442 and the barrel portion 41. Furthermore, because welding distortion can be reduced, jigs or the like for preventing welding distortion are not required.

[0044] The liquefied gas tank 1, 1A, 1B relating to the fourth item of the present disclosure is the liquefied gas tank 1, 1A, 1B relating to the second item, in which the peripheral surface of the annular plate 442 is joined to the inner wall of the cylindrical body 441, and the end face of the annular plate 442 is joined to the outer wall of the trunk portion 41.

[0045] According to the above-described liquefied gas tanks 1, 1A, and 1B, welding distortion can be reduced and excessive stress can be prevented by selecting an appropriate joint between the annular plate 442 and the barrel portion 41. Furthermore, because welding distortion can be reduced, jigs or the like for preventing welding distortion are not required.

[0046] The liquefied gas tank 1, 1A, 1B relating to the fifth item of the present disclosure is a liquefied gas tank 1 relating to any of the first to fourth items, in which the outer diameter D4 of the connection portion 44 is larger than the outer diameter D1 of the body portion 41 and is substantially the same as or larger than the outer diameter D2 of the head portion 42.

[0047] In this way, the outer diameter D4 of the connecting portion 44 can be any value that is not restricted by the head portion 42. Therefore, the difference between the outer diameter D4 of the connecting portion 44 and the outer diameter D1 of the body portion 41 can be designed according to the difference in the amount of deformation between the inner tank 31 and the pipe tower 4 to be absorbed.

[0048] A liquefied gas tank 1B according to the sixth item of the present disclosure is a liquefied gas tank 1, 1A, 1B according to any one of the first to fifth items, in which the connection portion 44 of the pipe tower 4 has a second deformation-permitting portion A2 between the inner tank joint 48 and the outer tank joint 49, which elastically deforms to permit vertical displacement of the inner tank joint 48 relative to the outer tank joint 49.

[0049] The liquefied gas tank 1B according to the seventh item of the present disclosure is the liquefied gas tank 1B according to the sixth item, wherein the second deformation-permitting portion A2 has a short cylinder 453 having a smaller diameter than the cylinder 441 inserted between the inner tank joint 48 and the outer tank joint 49 of the cylinder 441, and a pair of annular plates 451, 452 facing each other in the vertical direction, each having an outer edge joined to the cylinder 441 and an inner edge joined to the short cylinder 453.

[0050] In the liquefied gas tank 1B relating to the sixth and seventh items, the second deformation-permitting portion A2 permits the pipe tower 4 to be displaced vertically relative to the top of the outer tank 32 joined to the outer tank joint 49, and also permits the top of the inner tank 31 joined to the inner tank joint 48 to be displaced vertically relative to the top of the outer tank 32, thereby preventing high stress from occurring at the joints between the pipe tower 4 and the inner tank 31 and outer tank 32.

[0051] The liquefied gas tank 1B according to the eighth item of the present disclosure is the liquefied gas tank 1B according to the seventh item, in which a circumferentially continuous groove 45 is formed in the cylindrical body 441 by a short cylindrical body 453 and a pair of annular plates 451, 452, and the inside of the groove 45 is connected to the space between the inner tank 31 and the outer tank 32.

[0052] This allows the piping and wiring that are passed between the inner tank 31 and the outer tank 32 to be drawn out to the vicinity of the head 42 of the pipe tower 4 by using the recessed groove 45.

[0053] The liquefied gas tank 1, 1A, 1B according to the ninth item of the present disclosure is the liquefied gas tank 1, 1A, 1B according to any one of the first to eighth items, in which the lower end of the body 41 of the pipe tower 4 is joined to the inner tank without a member that allows deformation.

[0054] By increasing the rigidity of the lower part of the body 41 of the pipe tower 4 in this way, the entire pipe tower 4, which is a heavy object, can be well supported by the lower part of the body 41.

[0055] The foregoing discussion of the present disclosure has been presented for purposes of illustration and description and is not intended to limit the present disclosure to the form disclosed herein. For example, in the foregoing detailed description, various features of the present disclosure are grouped together in one embodiment and its variants for the purpose of streamlining the disclosure, but some of the multiple features may also be combined. Furthermore, multiple features included in the present disclosure may also be combined into alternative embodiments, configurations, or aspects other than those discussed above.

Claims

1. an inner tank for storing liquefied gas; an outer tank surrounding the inner tank; a cylindrical pipe tower extending in the vertical direction from the bottom wall of the inner tank, the pipe tower having a body portion having a lower end joined to the bottom wall of the inner tank, a head portion positioned above the outer tank, and a connecting portion penetrating the inner tank and the outer tank to connect the body portion and the head portion in the vertical direction, The connection portion of the pipe tower includes a cylindrical body extending in the vertical direction, the cylindrical body having an inner tank joint portion to which the top of the inner tank is joined and an outer tank joint portion to which the top of the outer tank is joined, and a first deformation-allowing portion that connects the cylindrical body to the upper end of the body portion and elastically deforms to allow displacement of the body portion relative to the cylindrical body. Liquefied gas tank.

2. the first deformable portion is an annular plate having an outer edge joined to a lower end of the cylindrical body and an inner edge joined to an upper end of the trunk portion, 2. The liquefied gas tank according to claim 1.

3. an upper surface of the annular plate is joined to an end surface of the cylindrical body, and a lower surface of the annular plate is joined to an end surface of the trunk portion; 3. The liquefied gas tank according to claim 2.

4. a peripheral surface of the annular plate joined to an inner wall of the cylindrical body, and an end surface of the annular plate joined to an outer wall of the trunk portion; 3. The liquefied gas tank according to claim 2.

5. The outer diameter of the connection portion is larger than the outer diameter of the body portion and is equal to or larger than the outer diameter of the head portion.

2. The liquefied gas tank according to claim 1.

6. the connection portion of the pipe tower has a second deformation-allowing portion between the inner tank joint portion and the outer tank joint portion, which elastically deforms to allow displacement of the inner tank joint portion in the up-down direction relative to the outer tank joint portion. The liquefied gas tank according to any one of claims 1 to 5.

7. The second deformation-allowing portion includes a short cylinder having a smaller diameter than the cylinder and inserted between the inner tank joint portion and the outer tank joint portion of the cylinder, and a pair of annular plates having an outer edge joined to the cylinder and an inner edge joined to the short cylinder and facing each other in the vertical direction.

7. The liquefied gas tank according to claim 6.

8. a groove that is continuous in the circumferential direction of the cylinder is formed by the short cylinder and the pair of annular plates, and the inside of the groove communicates with the inner tank and the outer tank; 8. The liquefied gas tank according to claim 7.

9. a lower end of the body portion of the pipe tower is joined to the inner tank without a member that allows deformation; The liquefied gas tank according to any one of claims 1 to 5.

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