Double-hulled tanks and ships

Abstract

To propose a structure which connects an outer tank and an inner tank body to an inner tank protruding part (an inner tank dome) protruding from the inner tank body in a double shell tank.SOLUTION: A double shell tank includes: an inner tank having an inner tank body in which a liquefied gas is stored, an inner tank protruding part protruding in a predetermined protruding direction farther than an inner tank opening provided at the inner tank body, and a connection part which connects an opening edge of the inner tank opening with the inner tank protruding part and in which a space surrounded by the inner tank body, the connection part, and the inner tank protruding part is formed; and an outer tank which houses the inner tank body and is joined to the inner tank protruding part. The connection part has an expansion / contraction structure which may expand in the protruding direction and contract by elastic deformation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a double-shell tank and a ship equipped with the same. [Background technology]

[0002] Liquefied gas carriers equipped with double-hull tanks have been known for some time. For example, Patent Document 1 discloses a liquefied gas carrier in which double-hull tanks mounted on the hull are covered with tank covers.

[0003] In the liquefied gas carrier disclosed in Patent Document 1, a vacuum layer is formed as an insulating layer between the inner and outer shells of a double-hull tank. More specifically, the inner shell includes an inner shell body that stores liquefied gas and an inner shell dome that protrudes upward from the inner shell body, and the outer shell includes an outer shell body that surrounds the inner shell body and an outer shell dome that surrounds the inner shell dome. The inner shell dome is a part that aggregates various pipes such as liquefied gas transfer pipes and electrical pipes, and is penetrated by these pipes.

[0004] Furthermore, in the double-shell tank of Patent Document 1, a bellows is incorporated in the outer dome. This bellows divides the outer dome into an upper movable part and a lower fixed part. When liquefied gas is introduced into the inner tank, the inner tank thermally contracts. The movable part of the outer dome is connected to the inner dome by a connecting member so that it displaces together with the inner dome when the inner tank thermally contracts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-4383 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the outer shell dome is divided into an upper movable part and a lower fixed part, the movable part and the fixed part are connected via a bellows, and the movable part of the outer shell dome and the inner shell dome are connected via a connecting member having an expandable part. In this way, in Patent Document 1, the inner shell and the outer shell are connected at the inner shell dome and the outer shell dome.

[0007] When a double-shell tank has an inner shell dome and an outer shell dome as in Patent Document 1, an access hole is required in each of the outer shell dome and the inner shell dome to form an access path from outside the tank to the inside of the inner shell. Furthermore, the access hole in the inner shell dome cannot be opened until the access hole in the outer shell dome has been opened and gas between the inner and outer shells has been purged. Given these circumstances, there is a demand for a double-shell tank that does not require an outer shell dome. In this case, the outer shell and the inner shell body are connected to the inner shell dome to ensure airtightness between the inner and outer shells. However, the issue here is how to accommodate relative displacement due to differences in the degree of thermal contraction between the outer shell and the inner shell body.

[0008] The present disclosure has been made in consideration of the above circumstances, and its purpose is to propose a structure for a double-shell tank in which an outer tank and an inner tank body are connected to an inner tank protrusion (inner tank dome) protruding from the inner tank body, and which can absorb relative displacement due to differences in the degree of thermal shrinkage between the outer tank and the inner tank body. [Means for solving the problem]

[0009] The double-shell tank according to the present disclosure comprises: The tank has an inner tank body that stores liquefied gas, an inner tank protruding portion that protrudes in a predetermined protruding direction beyond an inner tank opening provided in the inner tank body, and a connecting portion that connects the opening edge of the inner tank opening and the inner tank protruding portion, and the space surrounded by the inner tank body, the connecting portion, and the inner tank protruding portion the space including the interior of the inner tank protruding portion and the interior of the inner tank body, which are communicated through the connecting portion; A tank and an outer tank that houses the inner tank body and is joined to the inner tank protruding portion, The connecting portion has an expandable structure that can expand and contract in the protruding direction by elastic deformation.

[0010] A vessel according to the present disclosure is characterized by comprising a hull and the double-hull tank supported by the hull.

[0011] In the double-shell tank and the ship equipped with the double-shell tank having the above-mentioned configuration, the inner tank protrusion is joined to the outer tank and connected to the inner tank body via a connecting part. The connecting part has an expandable structure that can expand and contract in the protruding direction by elastic deformation, so that both the outer tank and the inner tank body can be structurally connected to the inner tank protrusion so that excessive load is not applied to the components of the double-shell tank even if relative displacement occurs between the inner tank body and the outer tank. [Effects of the Invention]

[0012] According to the present disclosure, a structure can be proposed in a double-shell tank in which the outer tank and the inner tank body are connected to an inner tank protruding portion (inner tank dome) protruding from the inner tank body. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic side view of a ship equipped with a double-shell tank according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of a double-shell tank. [Figure 3] FIG. 3 is an enlarged cross-sectional view of the top of the double-shell tank. [Figure 4] FIG. 4 is a diagram showing the state in which relative displacement occurs between the inner and outer tanks due to thermal contraction. [Figure 5] FIG. 5 is a schematic cross-sectional view of the top of a double-shell tank according to a first modified example. [Figure 6] FIG. 6 is a schematic cross-sectional view of the top of a double-shell tank according to a second modified example. [Figure 7] FIG. 7 is a schematic cross-sectional view of the top of a double-shell tank according to a third modified example. [Figure 8] FIG. 8 is a schematic cross-sectional view of the top of a double-shell tank according to a fourth modified example. [Figure 9] FIG. 9 is a schematic cross-sectional view of the top of a double-shell tank according to a fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification, the term "inside" refers to the side closer to the center of the space inside the inner tank of the double-shelled tank, and the term "outside" refers to the side farther from the center of the space inside the inner tank of the double-shelled tank.

[0015] [General configuration of ship 1] FIG. 1 is a schematic side view of a ship 1 equipped with a double-hull tank 2 according to this embodiment. As shown in FIG. 1, the ship 1 includes at least one double-hull tank 2 and a hull 11 that supports the double-hull tank 2. The ship 1 is a liquefied gas carrier that transports low-temperature liquefied gas. Examples of liquefied gas include LNG, liquefied nitrogen, liquefied hydrogen, and liquefied helium.

[0016] [Outline of double-shell tank 2] Fig. 2 is a schematic cross-sectional view of a double-shell tank 2. As shown in Figs. 1 and 2, the double-shell tank 2 comprises an inner tank 3 and an outer tank 4 that houses the inner tank 3. The outer tank 4 is surrounded by a tank cover 12 that covers the top and a retaining wall 14 that covers the sides and bottom. The top of the outer tank 4 may be covered by a part of the hull 11 instead of the tank cover 12. The retaining wall 14 may be formed by a part of the hull 11, for example.

[0017] Liquefied gas is stored in storage space 51 inside inner tank 3. An airtight space (hereinafter referred to as cold storage space 52) is formed between inner tank 3 and outer tank 4. Heat insulating material is arranged in cold storage space 52. Furthermore, cold storage space 52 is filled with gas whose boiling point is equal to or higher than the boiling point of the liquefied gas stored in storage space 51. In this embodiment, vaporized gas of the liquefied gas in storage space 51 is filled in cold storage space 52. In this way, when the gas filling storage space 51 and cold storage space 52 is the same, cold storage space 52 may be connected to cold storage space 52 inside inner tank 3.

[0018] A substantially sealed space (hereinafter referred to as holding space 53) is formed between the outer tank 4 and the tank cover 12 and the holding wall 14. The holding space 53 is filled with, for example, a non-flammable or flame-retardant gas such as nitrogen gas or inert gas, or dry air. The holding space 53 according to this embodiment is filled with nitrogen gas.

[0019] The inner tank 3 has an inner tank body 31, an inner tank protruding portion 32, and a connecting portion 37 that connects the inner tank body 31 and the inner tank protruding portion 32. A space surrounded by the inner tank body 31, the connecting portion 37, and the inner tank body 31 is formed inside the inner tank 3. The inner tank body 31 is a container for storing liquefied gas. The inner tank protruding portion 32 protrudes into an exposed space above the tank cover 12 so that piping passing through the interior of the inner tank 3 can be led directly to the exposed space without passing through other spaces, and a space communicating with the interior of the inner tank body 31 is formed inside. In this embodiment, the protruding direction X of the inner tank protruding portion 32 from the inner tank body 31 is the vertical direction. The inner tank protruding portion 32 is dome-shaped and includes a cylindrical peripheral wall and a ceiling wall that closes the upper opening of the peripheral wall.

[0020] The inner tank 3 is provided with a tower 20 that extends from the top of the inner tank protruding portion 32 to the bottom of the inner tank body 31. Although not shown, a pump for pumping liquefied gas is installed at the bottom of the tower 20. A liquid feed pipe and an electrical pipe are connected to the pump, and these liquid feed pipe and electrical pipe run through the tower 20, penetrate the exposed portion of the inner tank protruding portion 32, and extend to the outside. However, the pump located at the bottom of the tower 20 may be omitted.

[0021] The tower 20 is also penetrated by a pneumatic tube 91. The pneumatic tube 91 guides boil-off gas generated by the evaporation of liquefied gas in the inner tank 3 from the inner tank 3 through the inner tank protrusion 32 to other equipment outside the double-shell tank 2. Examples of other equipment include a propulsion engine, a power generation engine, a reliquefaction device, and an atmospheric release device. Furthermore, at least one inter-tank piping 92 passes through the cold insulation space 52 between the inner tank 3 and the outer tank 4. The inter-tank piping 92 may be appropriately supported by a structural member disposed in the cold insulation space 52. The inter-tank piping 92 may be any of a liquid supply pipe, an air supply pipe, and an electrical pipe. Specific examples of the inter-tank piping 92 include a purge pipe, a sampling pipe, and an air supply pipe. In the inner tank 3 and the outer tank 4, the portions through which piping such as the pneumatic tube 91 and the inter-tank piping 92 penetrate may be airtight to ensure airtightness between the tanks and the piping, and may be thermally insulated similarly to the tanks.

[0022] [Configuration of the top of the double-shell tank 2] Here, a detailed description will be given of the configuration of the top of the double-shell tank 2. Figure 3 is an enlarged cross-sectional view of the top of the double-shell tank 2.

[0023] As shown in Figure 3, an inner tank opening 35 is provided at the top of the inner tank body 31. The lower end of a connecting part 37 is joined to this inner tank opening 35. The connecting part 37 rises upward from the edge of the inner tank opening 35. The upper end of the connecting part 37 is rigidly joined to the inner wall of the inner tank protruding part 32 at the upper and lower midpoints. In other words, the upper part of the connecting part 37 is covered by the inner tank protruding part 32.

[0024] The inner tank body 31 is covered by the outer tank 4. In this embodiment, both the inner tank body 31 and the outer tank 4 are spherical. In addition to a perfect sphere, spherical shapes include spheres stretched in the vertical or horizontal directions (capsule shapes) and ellipses. However, the inner tank 3 and the outer tank 4 are not necessarily limited to a spherical shape and may be rectangular. An outer tank opening 44 is provided at the top of the outer tank 4, which is approximately concentric with the inner tank opening 35 of the inner tank 3, and this outer tank opening 44 is rigidly joined to the lower end of the peripheral wall of the inner tank protruding portion 32.

[0025] The inner tank protruding portion 32 is provided with a flange portion 39 that protrudes radially from the peripheral wall. The inner tank protruding portion 32 is loosely inserted in the vertical direction into an opening 12a provided in the tank cover 12. The flange portion 39 and the edge of the opening 12a of the tank cover 12 face each other in the vertical direction. They are connected by a bellows 13 that can expand and contract in the vertical direction. In this embodiment, a tubular bellows 13 having a bellows-shaped cross section is used. A rubber expansion joint may be used instead of the bellows 13.

[0026] The connecting portion 37 is composed of a combination of a ring plate member 37a and a cylindrical member 37b. At room temperature, the ring plate member 37a is a ring-shaped plate member whose thickness direction is the protruding direction X, and the cylindrical member 37b is a cylindrical member extending in the protruding direction X. The ring plate member 37a and the cylindrical member 37b may be composed of multiple plates joined together. The ring plate member 37a and the cylindrical member 37b have a plate thickness of, for example, about 10 to 60 mm and are made of the same material as the inner tank body 31. The connecting portion 37 composed of such a ring plate member 37a and cylindrical member 37b is interposed between the inner tank body 31 and the inner tank protruding portion 32 and can transmit loads.

[0027] When the inner peripheral edge and the outer peripheral edge of the ring-shaped ring plate member 37a are pulled apart in the protruding direction X, the ring plate member 37a easily elastically deforms, and the inner peripheral edge and the outer peripheral edge can be relatively displaced in the direction separating them in the protruding direction X. The cylindrical member 37b can also be stretched by elastic deformation when pulled in the protruding direction X, but the ring plate member 37a is more easily elastically deformed than the cylindrical member 37b. It is desirable that the ring plate member 37a be more easily elastically deformed than the inner tank main body 31 and the inner tank protruding portion 32.

[0028] The connecting portion 37 according to this embodiment is composed of a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a first ring plate member 37a whose outer periphery is joined to the upper end of the first cylindrical member 37b, a second cylindrical member 37b whose lower end is joined to the inner periphery of the first ring plate member 37a, and a second ring plate member 37a whose inner periphery is joined to the upper end of the second cylindrical member 37b. The outer periphery of the second ring plate member 37a is joined to the inner tank protrusion 32.

[0029] The upper end of the connecting portion 37 (i.e., the outer peripheral edge of the second annular plate member 37a) is joined to the inner wall of the inner tank protruding portion 32 at a position higher than the tank cover 12 and the flange portion 39. The second cylindrical member 37b has a smaller diameter than the inner tank protruding portion 32, and there is a gap between the second cylindrical member 37b and the inner tank protruding portion 32. In this way, the connecting portion 37 and the inner tank protruding portion 32 form a space inside the inner tank protruding portion 32 that is connected to the space between the outer tank 4 and the inner tank main body 31. This space becomes part of the cold insulation space 52 (i.e., additional cold insulation space 52) and is used for piping and cold insulation.

[0030] The inter-tank piping 92 passes through the cold insulation space 52 between the outer tub 4 and the inner tub body 31. The inter-tank piping 92 passes through the additional cold insulation space 52 between the inner tub protrusion 32 and the connecting portion 37. The portion of the inner tub protrusion 32 through which the inter-tank piping 92 passes is above the tank cover 12 and is exposed. In this way, the inter-tank piping 92 passes only through the cold insulation space 52 and is led directly to the exposed area. In other words, the inter-tank piping 92 is led directly to the exposed area without passing through the storage space 51 and the holding space 53.

[0031] Because the inner tank body 31 contains low-temperature liquefied gas, it thermally shrinks to a greater extent than the outer tank 4, causing relative displacement between the inner tank body 31 and the outer tank 4. Figure 4 shows the relative displacement between the inner tank 3 and the outer tank 4 caused by thermal contraction. In this figure, the deformation of the inner tank 3 due to thermal contraction is exaggerated. As shown in Figure 4, when the inner tank body 31 displaces relative to the outer tank 4 due to thermal contraction, the distance between the inner tank body 31 and the outer tank 4 increases. Because the inner tank protrusion 32, which is joined to the outer tank 4, is restrained by the outer tank 4, the inner tank body 31 displaces relative to the inner tank protrusion 32, and the distance between the inner tank body 31 and the inner tank protrusion 32 in the protrusion direction X also increases. The relative displacement between the inner tank body 31 and the inner tank protrusion 32 is absorbed by the extension of the connecting part 37 in the protrusion direction X. Specifically, when the connecting portion 37 is pulled in the protruding direction X by the inner tank protruding portion 32 and the inner tank body 31, the ring plate member 37a is mainly elastically deformed, and the connecting portion 37 extends in the protruding direction X.

[0032] [Modification of double-shell tank 2] Hereinafter, first to fifth modified examples of the double-shell tank 2 according to the above embodiment will be described. In the description of the modified examples, the same or similar members as those in the above embodiment will be denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0033] <First Modification> Fig. 5 is a schematic cross-sectional view of the top of a double-shell tank 2A according to a first modified example. As shown in Fig. 5, the double-shell tank 2A according to the first modified example differs from the double-shell tank 2 according to the above-described embodiment in the structure of the connecting portion 37. Therefore, the structure of the connecting portion 37 of the double-shell tank 2A according to the first modified example will be described in detail below.

[0034] In the double-shell tank 2A according to the first modification, the connecting portion 37 of the inner tank 3 comprises a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a first ring plate member 37a whose outer periphery is joined to the upper end of the first cylindrical member 37b, a second cylindrical member 37b whose lower end is joined to the inner periphery of the first ring plate member 37a, and a second ring plate member 37a whose inner periphery is joined to the upper end of the second cylindrical member 37b. The outer periphery of the second ring plate member 37a is joined to the lower end of the inner tank protrusion 32. This connecting portion 37 is located within the thickness between the inner tank body 31 and the outer tank 4.

[0035] In the double-shell tank 2A according to the first modification, when the inner tank body 31 is displaced relative to the outer tank 4 due to thermal contraction, the inner tank protruding portion 32 joined to the outer tank 4 is constrained by the outer tank 4, and the inner tank body 31 is displaced relative to the inner tank protruding portion 32. As a result, the distance between the inner tank body 31 and the inner tank protruding portion 32 in the protruding direction X increases, but the connecting portion 37 extends in the protruding direction X, so the connection between the inner tank body 31 and the inner tank protruding portion 32 is maintained without applying excessive load.

[0036] <Second Modification> Fig. 6 is a schematic cross-sectional view of the top of a double-shell tank 2B according to the second modified example. As shown in Fig. 6, the double-shell tank 2B according to the second modified example differs from the double-shell tank 2 according to the above-described embodiment in the structure of the connecting portion 37. Therefore, the structure of the connecting portion 37 of the double-shell tank 2B according to the second modified example will be described in detail below.

[0037] In the double-shell tank 2B according to the second modification, the connecting portion 37 of the inner tank 3 is composed of a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a first annular plate member 37a whose inner periphery is joined to the upper end of the first cylindrical member 37b, and a second cylindrical member 37b whose lower end is joined to the outer periphery of the first annular plate member 37a. The upper end of the second cylindrical member 37b is joined to the inner wall of the outer tank 4. The connecting portion 37 is located within the thickness between the inner tank body 31 and the outer tank 4. In the double-shell tank 2B according to the second modification, the inner tank protruding portion 32 and the connecting portion 37 are not directly joined. However, because the inner tank protruding portion 32 and the outer tank 4 are rigidly joined, the inner tank protruding portion 32 and the connecting portion 37 can be considered to be joined via a part of the outer tank 4.

[0038] In the double-shell tank 2B according to the second modification, when the inner tank body 31 is displaced relative to the outer tank 4 due to thermal contraction, the inner tank protruding portion 32 joined to the outer tank 4 is constrained by the outer tank 4, and the inner tank body 31 is displaced relative to the inner tank protruding portion 32. As a result, the distance between the inner tank body 31 and the inner tank protruding portion 32 in the protruding direction X increases, but the connecting portion 37 extends in the protruding direction X, so the connection between the inner tank body 31 and the inner tank protruding portion 32 is maintained without applying excessive load.

[0039] <Third Modification> Fig. 7 is a schematic cross-sectional view of the top of a double-shell tank 2C according to a third modified example. As shown in Fig. 7, the double-shell tank 2C according to the third modified example differs from the double-shell tank 2 according to the above-described embodiment in the structure of the connecting portion 37. Therefore, the structure of the connecting portion 37 of the double-shell tank 2C according to the third modified example will be described in detail below.

[0040] In the double-shell tank 2C according to the third modification, the connecting portion 37 of the inner tank 3 comprises a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a second cylindrical member 37b joined to the lower end of the inner tank protruding portion 32, and a cylindrical telescopic member 37c connecting the first cylindrical member 37b and the second cylindrical member 37b. The second cylindrical member 37b and the inner tank protruding portion 32 may be integrally formed. The telescopic member 37c is a member that can telescope in the protruding direction X. For example, a bellows pipe, a corrugated pipe, or a membrane may be used as the telescopic member 37c.

[0041] In the double-shell tank 2C according to the third modification, when the inner tank body 31 is displaced relative to the outer tank 4 due to thermal contraction, the inner tank protruding portion 32 joined to the outer tank 4 is constrained by the outer tank 4, and the inner tank body 31 is displaced relative to the inner tank protruding portion 32. As a result, the distance between the inner tank body 31 and the inner tank protruding portion 32 in the protruding direction X increases, but the connection between the inner tank body 31 and the inner tank protruding portion 32 is maintained without applying excessive load to the inner tank 4, as mainly the expandable member 37c of the connecting portion 37 extends in the protruding direction X.

[0042] <Fourth Modification> Fig. 8 is a schematic cross-sectional view of the top of a double-shell tank 2D according to a fourth modified example. As shown in Fig. 8, the double-shell tank 2D according to the fourth modified example differs from the double-shell tank 2 according to the previously described embodiment in that it includes an intermediate tank 6 between the inner tank 3 and the outer tank 4. The double-shell tank 2D can also be considered a triple-shell tank with three tank layers. The intermediate tank 6 is disposed between the inner tank 3 and the outer tank 4, with the inner tank 3 housed in the intermediate tank 6, and the intermediate tank 6 housed in the outer tank 4. The inner tank 3 and the intermediate tank 6 are spaced apart, forming a first cold-insulation space 52a between these tanks. The intermediate tank 6 and the outer tank 4 are also spaced apart, forming a second cold-insulation space 52b between these tanks.

[0043] The inner tank 3 has an inner tank body 31, an inner tank protrusion 32, and a connecting part 37 connecting the inner tank body 31 and the inner tank protrusion 32. The connecting part 37 is composed of a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a first ring plate member 37a whose inner peripheral edge is joined to the upper end of the first cylindrical member 37b, a second cylindrical member 37b whose lower end is joined to the outer peripheral edge of the first ring plate member 37a, a second ring plate member 37a whose outer peripheral edge is joined to the upper end of the second cylindrical member 37b, a third cylindrical member 37b whose lower end is joined to the inner peripheral edge of the second ring plate member 37a, and a third ring plate member 37a whose inner peripheral edge is joined to the upper end of the third cylindrical member 37b. The outer peripheral edge of the third ring plate member 37a is joined to the upper and lower middle parts of the inner wall of the inner tank protrusion 32. An intermediate tank opening 66 is provided at the top of the intermediate tank 6, and the opening edge of the intermediate tank opening 66 is joined to the second cylindrical member 37b. The outer tank opening 44 of the outer tank 4 is joined to the lower end of the inner tank protruding portion 32.

[0044] In the double-shell tank 2D according to the fourth modification, when the inner tank body 31 and the intermediate tank 6 are displaced relative to the outer tank 4 due to thermal contraction, the inner tank protruding portion 32, which is joined to the outer tank 4, is constrained by the outer tank 4, and the inner tank body 31 and the intermediate tank 6 are displaced relative to the inner tank protruding portion 32. As a result, the distance between the intermediate tank 6 and the inner tank protruding portion 32 in the protruding direction X increases, but the connecting portion 37 is extended in the protruding direction X mainly due to deformation of the second and third annular plate members 37a of the connecting portion 37, thereby maintaining the connection between the intermediate tank 6 and the inner tank protruding portion 32 without applying excessive load to the intermediate tank 6. Similarly, the distance between the inner tank body 31 and the inner tank protruding portion 32 in the protruding direction X increases, but the connecting portion 37 is extended in the protruding direction X mainly due to deformation of the first to third annular plate members 37a of the connecting portion 37, thereby maintaining the connection between the inner tank body 31 and the inner tank protruding portion 32 without applying excessive load to the inner tank body 31.

[0045] <Fifth Modification> FIG. 9 is a schematic cross-sectional view of the top of a double-shell tank 2E according to a fifth modified example. As shown in FIG. 9, the double-shell tank 2E according to the fifth modified example differs from the double-shell tank 2 according to the previously described embodiment in that the inner tank protrusion 32 has a flat roof shape rather than a dome shape. The tank cover 12 is not provided above the inner tank protrusion 32, so the inner tank protrusion 32 is exposed. The outer tank opening 44 of the outer tank 4 is rigidly connected to the inner tank protrusion 32. The outer tank 4 may be configured to surround the inner tank 3 independently of the hull 11, or may be configured to surround the inner tank 3 using the hull 11. In other words, the outer tank 4 may be formed by a part of the hull 11, such as the tank cover 12 or the retaining wall 14.

[0046] The inner tank protrusion 32 is connected to the inner tank 3 via a connecting part 37. The connecting part 37 is composed of a first cylindrical member 37b joined to the inner tank opening 35 of the inner tank body 31, a ring plate member 37a whose inner peripheral edge is joined to the upper end of the first cylindrical member 37b, and a second cylindrical member 37b whose lower end is joined to the outer peripheral edge of the ring plate member 37a. The upper end of the second cylindrical member 37b is joined to the inner tank protrusion 32.

[0047] In the double-shell tank 2E according to the fifth modification, when the inner tank body 31 is displaced relative to the outer tank 4 due to thermal contraction, the inner tank protruding portion 32, which is joined to the outer tank 4, is constrained by the outer tank 4, and the inner tank body 31 is displaced relative to the inner tank protruding portion 32. As a result, the distance between the inner tank body 31 and the inner tank protruding portion 32 in the protruding direction X increases, but the connecting portion 37 is extended in the protruding direction X due to deformation of mainly the ring plate member 37a of the connecting portion 37, and therefore the connection between the inner tank body 31 and the inner tank protruding portion 32 is maintained without applying excessive load to the inner tank body 31.

[0048] [Summary] As described above, the double-shell tanks 2, 2A to 2E according to this embodiment and the first to fifth modifications thereof are as follows: an inner tank (3) having an inner tank body (31) for storing liquefied gas, an inner tank protruding portion (32) protruding in a predetermined protruding direction (X) beyond an inner tank opening (35) provided in the inner tank body (31), and a connecting portion (37) connecting the opening edge of the inner tank opening (35) and the inner tank protruding portion (32), and forming an internal space surrounded by the inner tank body (31), the connecting portion (37), and the inner tank protruding portion (32); The container includes an inner tank body (31) and an outer tank (4) joined to an inner tank protrusion (32), The connecting portion 37 is characterized by having an expandable structure (annular plate member 37a or expandable member 37c) that can expand and contract in the protruding direction X by elastic deformation.

[0049] The ship 1 according to this embodiment is characterized by including a hull 11 and double-shell tanks 2, 2A to 2E supported by the hull 11.

[0050] In the double-shell tanks 2, 2A to 2E and the ship 1 equipped therewith having the above-described configuration, the inner tank protrusion 32 is joined to the outer tank 4, and the inner tank protrusion 32 is connected to the inner tank body 31 via the connecting part 37. The connecting part 37 has an expandable structure that can expand and contract in the protrusion direction X by elastic deformation, so that both the outer tank 4 and the inner tank body 31 can be structurally connected to the inner tank protrusion 32 so that even if relative displacement occurs between the inner tank body 31 and the outer tank 4, excessive load is not applied to the components of the double-shell tanks 2, 2A to 2E. More specifically, both the outer tank 4 and the inner tank body 31 can be structurally connected to the inner tank protrusion 32 so that excessive load is not applied to the inner tank 3 and the outer tank 4, the structural members connecting the inner tank 3 and the outer tank 4, and the piping (e.g., the pneumatic pipe 91 and the inter-tank piping 92) that penetrates the inner tank protrusion 32 due to relative displacement between the inner tank body 31 and the outer tank 4.

[0051] In the double-shell tanks 2, 2A, 2B, 2D, and 2E according to this embodiment and its first, second, fourth, and fifth modifications, the extendable structure of the connecting portion 37 includes a ring-shaped annular plate member 37a whose thickness direction is the protruding direction X. In this case, the connecting portion 37 may be configured by a combination of at least one annular plate member 37a and at least one tubular member 37b extending in the protruding direction X.

[0052] In the extendable structure of the connecting part 37 as described above, the inner and outer peripheral edges of the ring plate member 37a are pulled in opposite directions in the protruding direction X, causing the ring plate member 37a to extend in the protruding direction X. This elastic deformation of the ring plate member 37a allows the connecting part 37 to extend or contract in the protruding direction X. In addition, the ring plate member 37a functions as a structural member that transmits load between the inner tank main body 31 and the inner tank protruding part 32, and the connecting part 37 can support the inner tank main body 31 or the inner tank protruding part 32.

[0053] In addition, in the double-shell tank 2 of this embodiment, the connecting portion 37 of the inner tank 3 has a first end (lower end) joined to the opening edge of the inner tank opening 35 and a second end (upper end) joined to the inner wall of the inner tank protruding portion 32, and an additional cold storage space 52 continuous with the cold storage space 52 between the inner tank main body 31 and the outer tank 4 is formed between the inner wall of the inner tank protruding portion 32 and the outer wall of the connecting portion 37.

[0054] The additional cold insulation space 52 can be used for cold insulation within the connecting portion 37. The additional cold insulation space 52 can also be used as a space for passing the inter-tank piping 92 that passes between the inner tank body 31 and the outer tank 4. In this case, it is desirable that the inter-tank piping 92 passes through the cold insulation space 52 and the additional cold insulation space 52, and extends to the outside by penetrating the exposed portion of the inner tank protruding portion 32. In this way, the inter-tank piping 92 passes only through the cold insulation space 52 and is led out to the exposed portion without passing through the storage space 51 or the holding space 53.

[0055] In addition, in the double-shell tank 2D according to the fourth modification, an intermediate tank 6 accommodating the inner tank body 31 is provided between the inner tank body 31 and the outer tank 4, and the intermediate tank 6 has an intermediate tank opening 66 through which the connecting portion 37 passes, and the opening edge of the intermediate tank opening 66 is joined to the connecting portion 37. In this way, the structure of the double-shell tank 2 according to this embodiment can also be applied to a multi-shell tank having three or more tanks.

[0056] In the double-shell tank 2C according to the third modified example, the expandable structure of the connecting portion 37 includes a bellows pipe. In this way, the expandable structure of the connecting portion 37 is not limited to the ring plate member 37a.

[0057] Although the preferred embodiments of the present invention have been described above, the present invention also includes modifications of the specific structure and / or function of the above embodiments without departing from the spirit of the present invention. The above configuration can be modified, for example, as follows.

[0058] For example, the double-shell tanks 2, 2A to 2E according to the above embodiments are spherical (or rectangular) tanks independent of the hull 11, but they may also be membrane-type tanks that utilize the hull 11. In this case, the present invention can be applied to membrane-type tanks by replacing the inner tank 3 in the above embodiments with a membrane and the outer tank 4 with a barrier or hull.

[0059] For example, although the double-shell tanks 2, 2A to 2E in the above embodiments are cargo tanks, the double-shell tanks 2, 2A to 2E do not necessarily have to be installed as cargo tanks on the ship 1, and may be installed as fuel tanks. Furthermore, the number of double-shell tanks 2, 2A to 2E installed on the ship 1 is not specified. [Explanation of symbols]

[0060] 1: Ship 2, 2A-2E: Double-walled tank 3: Inner tank 4: Outer tank 6: Intermediate tank 11: Hull 31: Inner tank body 32: Inner tank protrusion 35: Inner tank opening 37:Connection part 37a: Ring plate member 37b: cylindrical member 52: Cooling space 66: Intermediate tank opening 92: Inter-tank piping X:Protrusion direction

Claims

1. an inner tank having an inner tank body that stores liquefied gas, an inner tank protruding portion that protrudes in a predetermined protruding direction beyond an inner tank opening provided in the inner tank body, and a connecting portion that connects the opening edge of the inner tank opening and the inner tank protruding portion, the inner tank having a space surrounded by the inner tank body, the connecting portion, and the inner tank protruding portion, the space including an interior of the inner tank protruding portion and an interior of the inner tank body that are communicated via the connecting portion; an outer tank that houses the inner tank body and is joined to the inner tank protruding portion, The connecting portion has an expandable structure that can expand and contract in the protruding direction by elastic deformation. Double-shell tank.

2. The expansion and contraction structure includes a ring-shaped annular plate member whose thickness direction is the protruding direction.

2. The double-shell tank according to claim 1.

3. The connecting portion is formed by a combination of at least one of the ring plate members and at least one tubular member extending in the protruding direction.

3. The double-shell tank according to claim 2.

4. the connecting portion has a first end joined to the opening edge of the inner tank opening and a second end joined to the inner wall of the inner tank protruding portion, An additional cold storage space continuous with the cold storage space between the inner tank body and the outer tank is formed between the inner wall of the inner tank protruding portion and the outer wall of the connecting portion. The double-shell tank according to any one of claims 1 to 3.

5. The cooling system further includes an inter-tank piping that passes through the cold storage space and the additional cold storage space, penetrates the exposed portion of the inner tank protruding portion, and extends to the outside.

5. The double-shell tank according to claim 4.

6. an intermediate tank that accommodates the inner tank body is provided between the inner tank body and the outer tank; The intermediate tank has an intermediate tank opening through which the connecting portion passes, and an opening edge of the intermediate tank opening and the connecting portion are joined. The double-shell tank according to any one of claims 1 to 5.

7. The telescopic structure includes a bellows tube.

2. The double-shell tank according to claim 1.

8. The hull and and a double-shell tank according to any one of claims 1 to 7 supported on the hull. ship.

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