Cryogenic liquid carrier

Abstract

To provide a low temperature liquid transportation vessel with less labor for construction compared to an LPG vessel or an LNG vessel and also improving economical efficiency by adopting a composition of integral with hull type tank method in a low temperature liquid transportation vessel storing liquefied ammonia or low temperature liquid of a substance liquefied at cooling temperature equivalent to liquefied ammonia in a tank.SOLUTION: A tank 3 is composed by one or more tank structures 31 composed by a plurality of partition walls built mainly using flat plate state steel plate for low temperature use inside an inner shell 12 and an upper deck 14. The tank structure 31 is covered by heatproof material 7. A coupling structure 4 coupling the inner shell 12 and the upper deck 14 with the tank structure 31 is composed by using stainless steel plate. One or more re-liquefaction apparatus 8 for liquefying gas generated in one or more tank structures are provided for the tank.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cryogenic liquid carrier in which a cryogenic liquid of liquefied ammonia or a substance liquefied at a cooling temperature equivalent to that of liquefied ammonia is stored in a tank, and a method for manufacturing the same.

Background Art

[0002] A liquefied gas carrier (cryogenic liquid carrier) is a ship that transports liquefied LNG, etc., which is a gas at normal temperature. There are ships that liquefy and transport it by applying a large pressure to make it liquid at normal temperature, or ships that use cryogenic cold insulation at a relatively high pressure to make it liquid and transport it (Type C independent tank ship), and ships that cool it to cryogenic temperature and keep it cold to make it liquid at normal pressure and transport it (Type A·B independent tank ship, membrane ship, integral tank ship), etc. The tank of a Type C independent tank ship is a high-pressure tank (pressure vessel). When it is enlarged, the shell (outer skin or outer shell) of the tank becomes extremely thick and it is not economically viable, so small tanks are mainly used. In order to economically increase the size and transport large quantities, a type that keeps it cold at cryogenic temperature and liquefies it at normal pressure is suitable. The temperature required for liquefaction in this case is -163°C for LNG, -50°C for LPG, -30°C for ammonia, etc.

[0003] Therefore, conventionally, LPG carriers for transporting liquefied petroleum gas (LPG) have been used for ammonia as well. This is because LPG carriers (independent tank type) transport LPG at -50°C, so it is relatively easy to use them for transporting liquefied ammonia at -30°C.

[0004] Japanese Utility Model Publication No. 10354 / 1971 (Patent Document 1) discloses a structure for a cryogenic liquefied gas (LNG) carrier in which a tank is supported by the hull using a sliding support material that has the dual functions of sliding support and insulation. This sliding support material does not fasten the tank to the hull, but is sandwiched between the shrinking tank and the unshrinking hull, allowing sliding when the tank thermally contracts due to the cryogenic liquid inside. In other words, the hull is not pulled by the tank, meaning that stress caused by tank contraction is not generated in the hull. The insulating material is a material with extremely low thermal conductivity (less than 1 / 100th that of steel), which suppresses heat inflow and prevents the liquefied gas in the tank from heating up and becoming a gas, enabling transportation in liquid form. This structure is a requirement for the independent tank system common to current LPG carriers, and sandwiching a support material that acts as both a sliding support and an insulating material without fastening the tank to the hull is a common and essential requirement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Jikko No. 10354-1971 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, currently, large amounts of liquefied ammonia (tens of thousands of m3 in liquefied form) are 3 The mainstream vessels used to transport ammonia to these temperatures (above) are LPG carriers operated as dual-purpose ammonia carriers. However, the temperature of liquefied ammonia is -30°C, which is higher than that of LNG (-163°C) or LPG (-50°C), and the impact of thermal stress on surrounding structures is relatively minor. Therefore, rather than using expensive vessels that require a great deal of effort to build due to the use of sliding support materials like LNG and LPG carriers, it is more economical to use cheaper vessels with simpler structures that can withstand higher temperatures.

[0007] An object of the present invention is to provide a cryogenic liquid carrier in which a cryogenic liquid of liquefied ammonia or a substance liquefied at a cooling temperature equivalent to that of liquefied ammonia is stored in a tank, and which adopts a tank system configuration integrated with the hull, so that it requires less construction effort compared to LPG carriers and LNG carriers and can improve economic efficiency, and a manufacturing method thereof.

Means for Solving the Problems

[0008] The present invention is directed to a cryogenic liquid carrier comprising a double hull having an outer hull and an inner hull, an upper deck, and a tank disposed inside the double hull and the upper deck, in which a cryogenic liquid of liquefied ammonia or a substance liquefied at a cooling temperature equivalent to that of liquefied ammonia is stored. In the present invention, the tank is constituted by one or more tank structures formed by a plurality of partition walls mainly constructed using flat cryogenic steel plates inside the inner hull and the upper deck. The one or more tank structures are covered with a heat insulating material. A connecting structure for connecting the inner hull, the upper deck, and the tank structure is constituted using a stainless steel plate. And one or more reliquefaction devices for liquefying the gas generated in the one or more tank structures with respect to the tank are provided.

[0009] In the case of a tank structure configured by a plurality of bulkheads mainly made of flat low-temperature steel plates inside the inner hull and the upper deck as in the present invention, in the process of manufacturing the hull, the tank structure can be manufactured together with the manufacturing of the double hull and the upper deck. Therefore, the manufacturing of the hull and the tank is easy, and the structure is extremely simple with a flat-plate main body, so the construction labor is greatly reduced. As a result, not only can the prices of the hull and the tank be lowered, but also the hull and the tank can be manufactured in a short period of time. In the case of an LPG ship, the direct heat intrusion path is only the heat-insulating resin that is the tank support material, and an extremely low temperature can be maintained. However, when the double hull, the upper deck, and the tank structure are connected via a connecting structure as in the present invention, the tank and the hull are directly connected by a metal connecting structure. Therefore, there arises a problem that the heat inflow from the outside increases. However, in the present invention, after covering the tank structure with a heat-insulating material, heat intrusion is suppressed by using a stainless steel plate with a low thermal conductivity for the main part or all of the connecting structure that connects the inner hull, the upper deck, and the tank structure. As a result of performing a heat conduction analysis on the integrated tank ship configured in this way, it was confirmed that even during navigation under high-temperature conditions, the heat balance can be maintained (liquefied ammonia can be transported in a liquid state) by using a reliquefaction device in combination. Also, in the stress analysis of the trial-designed hull, it was confirmed that the structural strength against the generated thermal stress is sufficient.

[0010] As a result, according to the present invention, a cryogenic liquid carrier in which a cryogenic liquid of liquefied ammonia or a substance that liquefies at a cooling temperature equivalent to that of liquefied ammonia is stored in a tank adopts a tank-type configuration integrated with the hull, so that it is possible to provide a cryogenic liquid carrier that requires less construction labor and can improve economic efficiency compared to LPG ships and LNG ships.

[0011] The tank structure includes an upper bulkhead and a lower bulkhead arranged at intervals in the vertical direction, a pair of beam bulkheads arranged at intervals in the longitudinal direction of the ship, and a pair of longitudinal bulkheads arranged at intervals in the beam direction orthogonal to the longitudinal direction of the ship. The tank structure with such a structure is mainly a combination of a simple triple hull structure composed of flat plates. Since the hull and the tank are assembled together, the construction effort is reduced.

[0012] Also, the tank structure includes an upper bulkhead and a lower bulkhead arranged at intervals in the vertical direction, where the length of the lower bulkhead in the beam direction orthogonal to the longitudinal direction of the ship is shorter than that of the upper bulkhead, a pair of beam bulkheads arranged at intervals in the longitudinal direction of the ship, and a pair of longitudinal bulkheads arranged at intervals in the beam direction orthogonal to the longitudinal direction of the ship. The pair of longitudinal bulkheads may include a first bulkhead portion extending in the vertical direction and a second bulkhead portion inclined to connect the first bulkhead portion and the lower bulkhead. The tank structure with such a structure is mainly a combination of a simple triple hull structure composed of flat plates. However, by including the second bulkhead portion inclined in the pair of longitudinal bulkheads, the strength is increased. Of course, the pair of longitudinal bulkheads may be composed only of the first bulkhead portion without including the inclined second bulkhead portion.

[0013] The upper bulkhead, the lower bulkhead, the pair of beam bulkheads, and the pair of longitudinal bulkheads may each be formed of grade E steel. If it is grade E steel, the required toughness can be ensured.

[0014] The connecting structure preferably has a structure including a plurality of transverses and a plurality of girders. The plurality of transverses have a plate-shaped portion extending in the ship width direction connecting the upper bulkhead and the upper deck, a plate-shaped portion extending in the ship width direction connecting the lower bulkhead and the inner shell, and a pair of plate-shaped portions extending in the vertical direction connecting a pair of longitudinal bulkheads and the inner shell, and are configured to surround the periphery of the tank when viewed from the longitudinal direction and are arranged at intervals in the longitudinal direction. The plurality of girders include one or more first girders extending in the longitudinal direction and connecting the upper bulkhead and the upper deck, one or more second girders extending in the longitudinal direction and connecting the lower bulkhead and the inner shell, and a pair of one or more third girders extending in the longitudinal direction and connecting a pair of longitudinal bulkheads and the inner shell. The one or more first girders, the one or more second girders, and the pair of one or more third girders are arranged at intervals in the circumferential direction of the tank when viewed from the longitudinal direction and have a structure orthogonal to the plurality of transverses. When the connecting structure is configured in this way, the thermal conductivity of the connecting structure can be reduced as much as possible, and the tank can be fixed.

[0015] Preferably, traffic through-holes for workers to pass through are formed in at least a part of the plurality of transverses and the first to third girders. By forming such traffic through-holes, the moving distance of the workers during the construction of the heat insulation material can be shortened, and the work efficiency can be improved.

[0016] Preferably, a reinforcing partition wall is provided at the central part inside the tank structure, which is connected to at least the upper bulkhead and the lower bulkhead and extends in the longitudinal direction to partition the inside of the tank. By providing the reinforcing partition wall, even when the tank structure is enlarged, the mechanical strength of the tank structure can be maintained.

[0017] A plurality of anti-flexure members extending in the longitudinal direction and / or a plurality of anti-flexure members extending in the ship width direction and the vertical direction may be welded to at least the outer surface portions of the upper bulkhead and the lower bulkhead of the tank structure, a pair of longitudinal bulkheads, and a pair of ship width direction bulkheads. By providing the anti-flexure members, the mechanical strength of each wall constituting the tank structure portion can be increased.

[0018] When the tank is composed of a plurality of tank structures arranged at intervals in the ship length direction, if the space between two adjacent tank structures is sized so that an operator can enter, the construction work and maintenance inspection work will be facilitated.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0020] The embodiments of the present invention will be described in detail with reference to the following drawings. FIGS. 1(A) and (B) are a schematic plan view and a schematic side view conceptually showing the configuration of the cryogenic liquid carrier 1 according to the embodiment of the present invention. As shown in FIGS. 1(A) and (B), the cryogenic liquid carrier 1 of the present embodiment includes a double hull 13 having an outer hull 11 and an inner hull 12, an upper deck 14, and four tank structures 31 that constitute a tank 3 disposed inside the double hull 13 and the upper deck 14. FIG. 2 is a schematic cross-sectional view of a portion including the tank 3 of an example of the cryogenic liquid carrier according to the embodiment of the cryogenic liquid carrier of the present invention as viewed from one side in the ship length direction L. FIG. 3 is a schematic perspective view used to explain the configuration of one tank structure 31 in the region III shown in FIG. 1(A). In FIG. 3, the ship width direction partition wall on the stern side is not shown. FIG. 4 is a schematic perspective view used to explain the configuration of a portion of two tank structures 31 in the region IV shown in FIG. 1(A).

[0021] The cryogenic liquid carrier of the present embodiment includes a double hull 13 having an outer hull 11 and an inner hull 12, an upper deck 14, and a tank 3 disposed inside the double hull 13 and the upper deck 14. A cryogenic liquid of liquefied ammonia or a substance that liquefies at a cooling temperature equivalent to that of liquefied ammonia is stored in the tank 3 composed of four tank structures 31. In FIG. 3, for ease of understanding, the outer hull 11, the inner hull 12, and the upper deck 14 are drawn as transparent. Also, the filling port used when filling the cryogenic liquid into the tank 3 is not shown.

[0022] As shown in FIGS. 1(A) and (B), the four tank structures 31 that constitute the tank 3 are arranged in four in the ship length direction L. The ship length direction length of one tank structure 31 is several tens of meters. The four tank structures 31 that constitute the tank 3 are each constituted by a plurality of partition walls mainly made of flat cryogenic steel plates inside the inner hull 12 and the upper deck 14 of the hull. In FIG. 4, the two opposing ship width direction partition walls 34 of the two tank structures 31 are drawn as transparent.

[0023] The tank structure 31 used in this embodiment includes an upper partition wall 32 arranged at an interval in the vertical direction, a lower partition wall 33 whose length in the ship width direction W orthogonal to the ship length direction L is shorter than that of the upper partition wall 32, a pair of ship width direction partition walls 34 arranged at an interval in the ship length direction L, and a pair of ship length direction partition walls 35 arranged at an interval in the ship width direction W orthogonal to the ship length direction L. The pair of ship length direction partition walls 35 includes a first partition wall portion 35A extending in the vertical direction and a second partition wall portion 35B inclined to connect the first partition wall portion 35A and the lower partition wall 33. Each partition wall and partition wall portion is joined by welding. The upper partition wall 32, the lower partition wall 33, the pair of ship width direction partition walls 34, and the pair of ship length direction partition walls 35 are each formed of a grade E steel plate, a low-temperature steel plate, or a stainless steel plate. These steel materials can ensure the toughness required for the steel materials even when exposed to low temperatures.

[0024] In this embodiment, the connecting structure 4 that connects the inner shell 12, the upper deck 14, and the tank structure 31 is configured using a stainless steel plate. The connecting structure 4 has a structure including a plurality of transoms 5 and a plurality of girders 61 to 63 (64). Each transom 5 has a plate-like portion 51 extending in the ship width direction that connects the upper bulkhead 32 and the upper deck 14, a plate-like portion 52 extending in the ship width direction that connects the lower bulkhead 33 and the inner shell 12, and a pair of plate-like portions 53 that connect the pair of longitudinal bulkheads 35 and the inner shell 12. And each transom 5 is continuously configured in an annular shape so as to surround the periphery of the tank 3 when viewed from the longitudinal direction L. The transoms 5 are arranged at intervals in the longitudinal direction L. Further, the plurality of girders include one or more first girders 61 extending in the longitudinal direction L that connect the upper bulkhead 32 and the upper deck 14, one or more second girders 62 extending in the longitudinal direction that connect the lower bulkhead 33 and the inner shell 12, and a third girder 63 extending in the longitudinal direction L that connects the pair of longitudinal bulkheads 35 and the inner shell 12. Note that FIG. 4 illustrates a case where a fourth girder 64 extending in the longitudinal direction L and connecting the pair of longitudinal bulkheads 35 and the inner shell 12 is arranged above the third girder 63. In the example shown in FIG. 3, the one or more first girders 61, the one or more second girders 62, and the pair of one or more third girders 63 are arranged at intervals in the circumferential direction of the tank 3 when viewed from the longitudinal direction L, and are orthogonal to the plurality of transoms 5. The transoms 5 and the plurality of girders 61 to 63 (64) are each constituted by a stainless steel plate.

[0025] As shown in FIG. 4, the transverse bulkheads 34 facing each other in the longitudinal direction of two adjacent tank structures 31 are connected to each other by a plate-like portion 55 extending in the transverse direction W. This plate-like portion 55 is provided to maintain the mechanical strength of the transverse bulkhead 34, and a plurality of them may be provided in the height direction H. Of course, in order to further increase the strength of the transverse bulkhead 34, a plate-like portion extending in the height direction H may be provided so as to be orthogonal to the plate-like portion 55. The plate-like portion 55 may be formed of a stainless steel plate, but of course, since it is not directly exposed to heat inflow from the outside, it may be formed of a low-temperature steel plate or a grade E steel plate. The plate-like portion 55 is used as a scaffold for a person to enter the space formed between the two opposing transverse bulkheads 34 of the two tank structures 31 for inspecting the outer surface of the heat insulation material.

[0026] Conventional LPG carriers are built with a double hull at the bottom and a single hull at the sides, and after integrating separately manufactured independent rectangular LPG tanks or dividing the LPG tanks into large numbers of parts, they are loaded into the hull. Therefore, since the tank itself becomes a single hull structure, it is like building another ship inside the ship, which requires double the construction effort. On the other hand, as in this embodiment, when it is a combination of a simple triple hull structure mainly composed of flat plates, the hull and the tank are assembled together, so the construction effort is reduced.

[0027] Also, as in this embodiment, when the connecting structure 4 is composed of a stainless steel plate, the thermal conductivity of the connecting structure 4 can be reduced as much as possible, and the tank 3 can be fixed. At least a part of the plurality of transformers 5 and the first to third girders 61 to 63 (64) may be formed with through holes for traffic for workers to pass through. By forming such through holes for traffic, the moving distance of the workers during the construction of the heat insulation material can be shortened, and the work efficiency can be improved.

[0028] As shown in Fig. 2, in this embodiment, the tank structure 31 is covered with a heat insulating material 7 such as polyurethane foam. In this embodiment, after covering the tank structure 31 with the heat insulating material 7, the main part or all of the connecting structure 4 that connects the inner shell 12 and the upper deck 14 to the tank structure 31 is configured using a stainless steel plate with low thermal conductivity to suppress the intrusion heat. And for the tank 3, at least one or more re-liquefaction devices 8 for liquefying the gas generated in the tank structure 31 are provided.

[0029] As a result of performing a heat conduction analysis on the integrated tank ship configured as described above, it was confirmed that even during navigation under high-temperature conditions, by using the re-liquefaction device 8 in combination, the heat balance can be maintained (liquefied ammonia can be transported in a liquid state).

[0030] When using the tank structure 31 configured by a plurality of partition walls mainly made of flat low-temperature steel plates for the tank 3 inside the inner shell 12 and the upper deck 14 as in this embodiment, in the manufacturing process of the hull, the tank structure 31 can be manufactured together with the manufacturing of the double hull 13 and the upper deck 14. Therefore, the manufacturing of the tank is easy and the structure is extremely simple mainly composed of flat plates, so the construction labor is greatly reduced. As a result, not only can the prices of the hull and the tank 3 be reduced, but also the hull and the tank 3 can be manufactured in a short period.

[0031] Figs. 5 and 6 are detailed views showing a specific configuration including the anti-flexure members 9, 10A, and 10B when actually manufacturing the configuration of Figs. 3 and 4. In Figs. 5 and 6, the same members as those shown in Figs. 1 to 4 are denoted by the same reference numerals and the description thereof is omitted. In Figs. 5 and 6, a plurality of stiffeners welded to the outer surface portions of the upper partition wall 32, the lower partition wall 33, and the longitudinal partition wall 35 and having an L-shaped cross-sectional shape extending in the longitudinal direction are anti-flexure members 9 for preventing the bending of the longitudinal partition wall. Also in Fig. 5, the portion drawn by a dotted line at the center of the plate-like portions 51 to 53 constituting the transformer 5 is an anti-flexure member 10A for preventing the bending of these plate-like portions 51 to 53. Further, a plurality of anti-flexure members 10B are arranged at intervals so as to be orthogonal to the anti-flexure member 10A.

[0032] FIG. 7 is a diagram for explaining the configuration of the second embodiment of the present invention. In FIG. 7, members similar to those used in the configuration of the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals as those of the members shown in FIGS. 1 to 3, and the description thereof is omitted. The first embodiment shown in FIGS. 2 to 6 is configured to strengthen the structure of a large ship by forming a pair of longitudinal bulkheads 35 of the tank structure 31 with a first bulkhead portion 35A extending in the vertical direction and a second bulkhead portion (hopper inclined portion) 35B that is inclined to connect the first bulkhead portion 35A and the lower bulkhead 33. In the second embodiment shown in FIG. 7, for medium-sized ships, the second bulkhead portion (hopper inclined portion) 35B that is inclined from the longitudinal bulkhead 35 is eliminated, and the longitudinal bulkhead 35 is extended straight, which is different from the first embodiment. In the case of small and medium-sized ships, the structural strength can be achieved even without a hopper portion. Therefore, if the structure of the second embodiment shown in FIG. 7 is adopted, the construction man-hours can be reduced with a simpler structure.

[0033] As shown by the dashed line in FIG. 2, a reinforcing bulkhead 15 may be provided at the central portion inside the tank structure 31 and connected to at least the upper bulkhead 32 and the lower bulkhead 33 to partition the inside of the tank. By providing the reinforcing bulkhead 15, the mechanical strength of the tank structure 31 can be maintained even when the tank structure 31 is enlarged.

Industrial Applicability

[0034] According to the present invention, by adopting a tank system configuration integrated with the hull for a cryogenic liquid carrier in which a cryogenic liquid of liquefied ammonia or a substance liquefied at a cooling temperature equivalent to that of liquefied ammonia is stored in a tank, it is possible to provide a cryogenic liquid carrier that requires less construction effort compared to LPG carriers and LNG carriers and can improve economic efficiency.

Explanation of Reference Numerals

[0035] 1 Cryogenic liquid carrier 11 Outer hull 12 Inner hull 13 Double hull 14 Upper deck 3 Tank 31 Tank structure 32 Upper bulkhead 33 Lower bulkhead 34 Transverse bulkhead 35 Longitudinal bulkhead 4 Connecting structure 5 Transformer 61 - 63 Girder 7 Heat insulation material 8 Re - liquefaction device 9, 10A, 10B Anti - deflection material

Claims

1. A cryogenic liquid carrier comprising a double hull having an outer hull and an inner hull, an upper deck, and a tank disposed inside the double hull and the upper deck, wherein a cryogenic liquid of liquefied ammonia or a substance that liquefies at a cooling temperature equivalent to that of liquefied ammonia is stored in the tank, the tank consists of one or more tank structures constructed by a plurality of partition walls made of flat E-class steel plates, cryogenic steel plates, or stainless steel plates inside the inner hull and the upper deck, the tank structure is covered with a heat insulating material, the connecting structure connecting the inner hull, the upper deck, and the tank structure is composed of stainless steel plates, the cryogenic liquid carrier is characterized in that one or more reliquefaction devices for liquefying the gas generated in the tank structure with respect to the tank are provided.

2. The cryogenic liquid carrier according to claim 1, wherein the tank structure includes an upper partition wall and a lower partition wall disposed at intervals in the vertical direction and facing the upper partition wall, a pair of side partition walls disposed at intervals in the longitudinal direction of the ship, and a pair of longitudinal partition walls disposed at intervals in the breadth direction perpendicular to the longitudinal direction of the ship.

3. The tank structure includes an upper partition wall and a lower partition wall disposed at intervals in the vertical direction and having a shorter length in the breadth direction perpendicular to the longitudinal direction of the ship than the upper partition wall, a pair of side partition walls disposed at intervals in the longitudinal direction of the ship, and a pair of longitudinal partition walls disposed at intervals in the breadth direction perpendicular to the longitudinal direction of the ship, the cryogenic liquid carrier according to claim 1, wherein the pair of longitudinal partition walls includes a first partition wall portion extending in the vertical direction and a second partition wall portion inclined to connect the first partition wall portion and the lower partition wall.

4. The connecting structure has a plate-like portion extending in the breadth direction connecting the upper partition wall and the upper deck, a plate-like portion extending in the breadth direction connecting the lower partition wall and the inner hull, and a pair of plate-like portions extending in the vertical direction connecting the pair of longitudinal partition walls and the inner hull, and is configured to surround the periphery of the tank when viewed from the longitudinal direction, and a plurality of transformers disposed at intervals in the longitudinal direction. One or more first girders extending in the longitudinal direction of the ship and connecting the upper bulkhead and the upper deck, one or more second girders extending in the longitudinal direction of the ship and connecting the lower bulkhead and the inner hull, and a pair of one or more third girders extending in the longitudinal direction of the ship and connecting the pair of longitudinal bulkheads and the inner hull, The cryogenic liquid carrier according to claim 2 or 3, wherein the one or more first girders, the one or more second girders, and the pair of one or more third girders are arranged at intervals in the circumferential direction of the tank as viewed from the longitudinal direction of the ship and have a structure perpendicular to the plurality of transformers.

5. The cryogenic liquid carrier according to claim 4, wherein traffic through-holes through which workers can pass are formed in at least a part of the plurality of transformers and the first to third girders.

6. The cryogenic liquid carrier according to claim 2 or 3, wherein a reinforcing bulkhead that is at least connected to the upper bulkhead and the lower bulkhead and extends in the longitudinal direction to partition the inside of the tank is provided at the central part within the tank structure.

7. The cryogenic liquid carrier according to claim 2, wherein a plurality of anti-flexure members extending in the longitudinal direction and / or a plurality of anti-flexure members extending in the breadth direction and the vertical direction are welded to at least the outer surface portions of the upper bulkhead and the lower bulkhead, the pair of longitudinal bulkheads, and the pair of breadthwise bulkheads of the tank structure.

8. The one or more tank structures are composed of a plurality of tank structures arranged at intervals in the longitudinal direction of the ship, The cryogenic liquid carrier according to claim 2 or 3, wherein the space between two adjacent tank structures has a dimension that allows an operator to enter.

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