Piping structure for extremely low temperature liquid and ship provided with the same

Abstract

A piping structure for extremely low-temperature liquid is applied to a ship that stores an extremely low-temperature liquid having a boiling point of -196°C or lower under normal pressure. The piping structure includes a low-temperature pipe (10) that is arranged along a structural member (4) of the ship (1) at a position that is apart upward from the structural member (4) and that allows the extremely low-temperature liquid to flow therethrough, and a storage region dividing member (20) that is provided on the structural member (4) and that divides a storage region (AR) capable of storing an evaporation promoting liquid on the structural member (4), the evaporation promoting liquid receiving a drop of liquefied air formed on a surface of the low-temperature pipe (10) and evaporating the drop.

Description

Technical Field

[0001] This invention relates to a piping structure and a vessel suitable for storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure. Background Technology

[0002] As a type of piping for flowing extremely low-temperature liquids as described above, the piping described in Patent Document 1 is known. Specifically, the piping in Patent Document 1 is a double-structured piping (double pipe) for flowing liquefied hydrogen with a boiling point of -253°C at atmospheric pressure, having an inner pipe and an outer pipe arranged concentrically. A vacuum layer is formed between the inner and outer pipes to isolate heat transfer. Through the insulating effect of this vacuum layer, the liquefied hydrogen inside the inner pipe is maintained at a temperature below its boiling point.

[0003] In the double tube for liquefied hydrogen described in Patent Document 1, when the vacuum level of the aforementioned insulation layer decreases, heat transfer from the inner tube to the outer tube is likely to occur, reducing the temperature difference between the outer and inner tubes. When the temperature of the outer tube drops to a temperature close to that of the liquefied hydrogen inside the inner tube, air condensation may occur on the surface of the outer tube.

[0004] When liquefied air, containing liquefied nitrogen or liquefied oxygen, is formed on the surface of the outer tube, this liquefied air drips down the surface of the outer tube onto structural components of the ship's hull located below the double tube. In this case, the structural components are significantly cooled by the liquefied air. Since these structural components are typically made of ordinary structural soft steel, they are susceptible to cryogenic embrittlement due to the temperature drop when cooled by liquefied air.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2017-20914 Summary of the Invention

[0008] The present invention was made in view of the above circumstances, and its object is to provide a piping structure and a ship for cryogenic liquids that can suppress the embrittlement of structural components of the ship caused by the dripping of liquefied air formed on the surface of the piping as the temperature of the piping flows through the cryogenic liquid.

[0009] One aspect of the present invention relates to a piping structure for cryogenic liquids, suitable for ships storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure, and comprising: cryogenic piping arranged along a structural component at a position upward relative to the structural component of the ship, allowing the cryogenic liquid to flow; and a storage area dividing member disposed on the structural component, dividing a storage area capable of storing an evaporation-promoting liquid on the structural component, wherein the evaporation-promoting liquid, in the event of liquefied air forming on the surface of the cryogenic piping, receives and evaporates the dripping liquefied air.

[0010] Another aspect of the invention relates to a vessel for storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure, and includes: a hull having designated structural components; the aforementioned piping structure for cryogenic liquids; and a supply device capable of supplying the evaporation-promoting liquid to the storage area defined on the structural components by the storage area dividing member. Attached Figure Description

[0011] Figure 1 This is a side view showing a simplified structure of a ship to which a piping structure for cryogenic liquids according to an embodiment of the present invention is applied.

[0012] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0013] Figure 3 This is a cross-sectional perspective view showing the structure of the hydrogen piping.

[0014] Figure 4 This is a side view showing the piping structure for cryogenic liquids.

[0015] Figure 5 It is along Figure 4 A cross-sectional view of the VV line.

[0016] Figure 6 It is a three-dimensional view showing the storage area on the upper side of the can lid, which is divided by the storage area dividing component.

[0017] Figure 7 This is a perspective view showing a modified example of a storage area divided on the upper side of the can lid by a storage area dividing member. Detailed Implementation

[0018] Hereinafter, with reference to the accompanying drawings, we will describe the piping structure for cryogenic liquids and the ship for storing and transporting cryogenic liquids according to embodiments of the present invention.

[0019] Figure 1 and Figure 2This is a simplified side view and cross-sectional view illustrating the structure of a ship with a piping structure for cryogenic liquids according to an embodiment of the present invention. The ship 1 shown in the figure is for storing and transporting liquefied hydrogen L(…). Figure 2 The liquefied hydrogen transport vessel 1 comprises a hull 2 ​​and multiple tanks 3 mounted on the hull 2. The liquefied hydrogen L transported and stored by the vessel 1 is hydrogen in a liquid state cooled to a temperature below its boiling point of -253°C under normal pressure, which is an example of a cryogenic liquid in this invention.

[0020] The hull 2 ​​has multiple upward-opening cargo compartments 5 in the areas corresponding to each tank 3. A partition wall 6 is formed between adjacent cargo compartments 5 to separate the two cargo compartments 5 from each other.

[0021] In addition, the hull 2 ​​has decks 7 around the cargo hold 5. Deck 7 includes: a bow deck 7a located forward of the cargo hold 5; a pair of side decks 7b and 7c located to the left and right of the cargo hold 5; and a stern deck 7d located aft of the cargo hold 5. The hull 2 ​​is made of steel other than low-temperature steel. For example, each deck 7a to 7d is formed of ordinary structural mild steel. There are no particular limitations on the type of structural mild steel; as an example, SS material (ordinary structural rolled steel) as specified in JIS standards can be used.

[0022] Each tank 3 is a cylindrical tank that is longer along the length of the ship 1 and is housed in the cargo hold 5. Each tank 3 has an inner tank 3a for storing liquefied hydrogen L and an outer tank 3b arranged concentrically on the outside of the inner tank 3a. A vacuum layer 3c for heat insulation is formed between the inner tank 3a and the outer tank 3b. The vacuum layer 3c is a sealed space that can communicate with a suction device not shown in the figure.

[0023] Each tank 3 is topped with a tank cover 4. Each tank cover 4 forms part of the hull 2 ​​and, together with the cargo hold 5, forms the receiving space S for the tank 3. Similar to the hull 2, the tank cover 4 is made of steel other than cryogenic steel. For example, the tank cover 4 is formed of ordinary structural mild steel such as the aforementioned SS material. In other words, the tank cover 4 is made of steel that is more prone to cryogenic embrittlement than cryogenic steel, which is embrittlement that occurs under extremely low temperature conditions.

[0024] A hydrogen piping 10 is disposed above the tank cover 4. The hydrogen piping 10 is a conduit used by the vessel 1 to allow the flow of liquefied hydrogen L from the tank 3 during loading and unloading. The hydrogen piping 10 is arranged at a position relative to the upper side of the tank cover 4, bending and extending accordingly along the upper side of the tank cover 4. Furthermore, the hydrogen piping 10 corresponds to an example of "cryogenic piping" in this invention. Furthermore, the tank cover 4 located below the hydrogen piping 10 corresponds to an example of a structural component of the vessel in this invention.

[0025] Figure 3 This is a cross-sectional perspective view showing the structure of the hydrogen piping 10. As shown in the figure, the hydrogen piping 10 is a multi-pipe system comprising an inner pipe 10a, an outer pipe 10b, and a vacuum layer 10c. The inner pipe 10a allows liquefied hydrogen L to flow inside, the outer pipes 10b are concentrically arranged outside the inner pipe 10a, and the vacuum layer 10c is formed between the inner pipe 10a and the outer pipe 10b for heat insulation. The vacuum layer 10c is formed via... Figure 1 , 2 The suction port 11 shown provides a sealed space that can communicate with the suction device 12. Furthermore, as... Figure 1 As shown, a detector 13 for detecting the vacuum level of vacuum layer 10c is connected to the suction device 12. Details will be described later. The vacuum level of vacuum layer 10c detected by detector 13 serves as an indicator of whether liquefied air, formed from nitrogen or oxygen condensation in the air, has formed on the surface of outer tube 10b. Furthermore, detector 13 can also detect the surface temperature of hydrogen piping 10, specifically the surface temperature of outer tube 10b, instead of detecting the vacuum level of vacuum layer 10c. Similar to the vacuum level of vacuum layer 10c, the surface temperature of outer tube 10b serves as an indicator of whether liquefied air has formed on its surface.

[0026] In this embodiment, at least the inner pipe 10a in the hydrogen piping 10 is formed of low-temperature steel that is difficult to become brittle even under extremely low temperature conditions.

[0027] In this embodiment, the outer tube 10b is formed of cryogenic steel. The material of the outer tube 10b does not necessarily have to be cryogenic steel; it can also be various metals or resins.

[0028] Figure 4 and Figure 5 These are side views and cross-sectional views illustrating a piping structure for cryogenic liquids according to an embodiment of the present invention. Furthermore, in Figure 5 In the cross-sectional view, liquefied hydrogen L is omitted (see reference). Figure 3 (Illustration of the interior of inner tube 10a) Figure 6 This is a perspective view showing the storage area AR on the upper side of the tank cover 4, which is divided by the storage area dividing member 20. In the following description, the direction parallel to the axis of the hydrogen piping 10 is called the pipe axis X, and the direction orthogonal to the pipe axis X and the vertical direction (plumb line) is called the pipe axis orthogonal direction Y.

[0029] The piping structure for cryogenic liquids is a piping structure suitable for storing and transporting liquefied hydrogen L, which is a cryogenic liquid, in a ship 1. In addition to the hydrogen piping 10 mentioned above, it also has storage area dividing components 20 and multiple support components 30.

[0030] like Figure 4As shown, the hydrogen piping 10 has a structure formed by joining multiple unit pipes 10A of specified lengths along the pipe axis X. In the hydrogen piping 10, each of the multiple unit pipes 10A is connected via a suction port 11 to a suction device 12 for maintaining the vacuum layer 10c. That is, the vacuuming of the vacuum layer 10c in the hydrogen piping 10 by the suction device 12 is not performed along the entire length of the hydrogen piping 10, but separately for each unit pipe 10A. As a result, the vacuum layer 10e in the hydrogen piping 10 can be rapidly brought to a specified vacuum level, and in the event of a decrease in the vacuum level of the vacuum layer 10c, this phenomenon can be limited to a local area of ​​the hydrogen piping 10. Furthermore, a detector 13 is connected to each suction device 12. That is, the vacuum level of the vacuum layer 10c of each of the multiple unit pipes 10A is detected separately based on each detector 13.

[0031] Multiple supports 30 are arranged side-by-side along the pipe axis X on the upper side of the tank cover 4. Each support 30 supports and contacts the hydrogen piping 10 at a position relative to the tank cover 4 that is upwardly away from it. Each support 30 has a seat 31, a pair of legs 32, and a fixing member 33.

[0032] The seat 31 is a plate-shaped component extending orthogonally to the pipe axis in the Y direction and is positioned directly below the hydrogen pipe 10. The hydrogen pipe 10 is fixed to the upper side of the seat 31 by a fastener 33. In other words, the seat 31 directly supports the hydrogen pipe 10 by contacting its lower side. Specifically, the seat 31 supports the outer pipe 10b by contacting its lower side.

[0033] The fastener 33 is a fastener formed in an inverted U-shape when viewed from the front. In this embodiment, the fastener 33 is a U-bolt. Specifically, the fastener 33 has an upper portion 33a extending along the orthogonal direction Y of the tube axis, and a pair of side portions 33b extending downward from both ends of the upper portion 33a. The pair of side portions 33b are fastened to the seat portion 31 from above at positions on the left and right sides of the hydrogen pipe 10. Thus, the hydrogen pipe 10 is clamped between the upper portion 33a and the seat portion 31, and the hydrogen pipe 10 is fixed to the support member 30. In addition, a lubricating member or a low-friction member may be arranged between the outer tube 10b and the seat portion 31 to allow relative movement between the outer tube 10b and the seat portion 31 due to thermal shrinkage, etc.

[0034] A pair of legs 32 are formed extending downward from the left and right ends of the seat 31, that is, from the ends of the tube in the seat 31 in the orthogonal direction Y. The lower end of each leg 32 is fixed to the upper side of the lid 4.

[0035] The support member 30 is formed of a low-temperature steel that is resistant to embrittlement even at extremely low temperatures. For example, the various parts constituting the support member 30, namely the seat 31, the legs 32, and the fixing member 33, can be formed of austenitic stainless steel, which is a type of low-temperature steel. Low-carbon stainless steels such as SUS304L or SUS316L as specified in JIS standards are particularly preferred as austenitic stainless steel. Of course, other low-temperature steels or aluminum alloys can also be used.

[0036] The storage area dividing member 20 is disposed on the upper side of the can lid 4, protruding upward from the upper side of the can lid 4. The storage area dividing member 20 divides the upper side of the can lid 4 into a storage area AR for storing the evaporation promoting liquid. The storage area AR, which is divided on the upper side of the can lid 4, is located below the hydrogen pipe 10. When the evaporation promoting liquid stored in the storage area AR forms liquefied air on the surface of the outer pipe 10b as the temperature of the outer pipe 10b decreases, it catches the dripping liquefied air and evaporates it. The evaporation promoting liquid can be any substance that does not chemically react with the liquefied air dripping from the hydrogen pipe 10 and is in a liquid state at room temperature. Examples of such evaporation promoting liquids include fresh water, water mixed with unavoidable impurities, and brine. In this embodiment, seawater, which is a brine, is used as the evaporation promoting liquid.

[0037] The storage area dividing member 20 has a structure composed of multiple longitudinal beams 21 and multiple transverse beams 22. The longitudinal beams 21 extend along the pipe axis X, and the transverse beams 22 connect the longitudinal beams 21 in the orthogonal direction Y of the pipe axis. Each longitudinal beam 21 defines the end of the storage area AR in the orthogonal direction Y of the pipe axis on the upper side of the tank cover 4, and each transverse beam 22 defines the end of the storage area AR in the pipe axis X. Each longitudinal beam 21 and each transverse beam 22 has a thickness sufficient to store seawater, which serves as an evaporation-promoting liquid, within the storage area AR; this thickness can be, for example, set to approximately tens to hundreds of millimeters. Each longitudinal beam 21 and each transverse beam 22 can be formed of austenitic stainless steel, a type of low-temperature steel. Alternatively, each longitudinal beam 21 and each transverse beam 22 can be formed of the same ordinary structural mild steel as the tank cover 4. Each longitudinal beam 21 and each transverse beam 22 is fixed to the upper side of the can cover 4 by welding or the like.

[0038] In this embodiment, such as Figure 4 and Figure 6 As shown, the storage area dividing member 20 divides multiple storage areas AR along the pipe axis X of the hydrogen piping 10 on the upper side of the tank cover 4. At this time, the storage area dividing member 20 divides multiple storage areas AR on the upper side of the tank cover 4 in such a way that each storage area AR is located below each unit pipe 10A constituting the hydrogen piping 10.

[0039] like Figure 1 As shown, the vessel 1 also has a supply device 8 for evaporation-promoting liquid and a control device 9.

[0040] An evaporation-promoting liquid supply device 8 is disposed on the hull 2. The evaporation-promoting liquid supply device 8 supplies the evaporation-promoting liquid to the storage areas AR. In this embodiment, the evaporation-promoting liquid supply device 8 is a seawater supply device 8. The seawater supply device 8 is a device that supplies seawater to each storage area AR, which is divided on the upper side of the tank cover 4 by the storage area dividing member 20. The seawater supply device 8 draws seawater from outside the hull 2 ​​and supplies the drawn seawater to each storage area AR. Ideally, the seawater supply device 8 supplies seawater to each storage area AR in such a way that the water level of the seawater stored in each storage area AR is approximately the same level as or slightly less than the thickness of each longitudinal beam 21 and each transverse beam 22.

[0041] Between the seawater supply unit 8 and each storage area AR, a main seawater flow pipe 8a and multiple secondary seawater flow pipes 8b are installed for seawater flow. The main seawater flow pipe 8a extends from the seawater supply unit 8 to the side deck 7b and is installed on the side deck 7b. Each secondary seawater flow pipe 8b branches from the main seawater flow pipe 8a and extends to each storage area AR located below each unit pipe 10A. Each secondary seawater flow pipe 8b is equipped with an on / off valve 8c. By opening and closing each on / off valve 8c, the seawater supply unit 8 can supply seawater to each storage area AR.

[0042] The control device 9 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) storing the control program, and RAM (Random Access Memory) serving as the CPU's working area. The control device 9 controls the seawater supply device 8 and each of the on / off valves 8c by executing the control program stored in the ROM through the CPU. Furthermore, each detector 13 is electrically connected to the control device 9. Thus, information on the vacuum level of the vacuum layer 10c of each of the plurality of unit tubes 10A detected by each detector 13 is input to the control device 9.

[0043] When the vacuum level of the vacuum layer 10c of each unit pipe 10A detected by each detector 13 deviates from a preset allowable range, the control device 9 controls the seawater supply device 8 and each on / off valve 8c to store seawater in each storage area AR. When the vacuum level of the vacuum layer 10c detected by each detector 13 deviates from the specified allowable range, the possibility of liquefied air forming on the surface of the hydrogen piping 10 increases. In such a case, the control device 9 controls the seawater supply device 8 and each on / off valve 8c to supply seawater to each storage area AR divided on the upper side of the tank cover 4.

[0044] As described above, in this embodiment, the storage area AR, which can store seawater as an evaporation-promoting liquid, is divided on the upper side of the tank cover 4 by the storage area dividing member 20, and the hydrogen piping 10 is supported by the support member 30 made of cryogenic steel. Therefore, it has the advantage that the tank cover 4 can be suppressed from the effect of dripping liquefied air formed on the surface of the hydrogen piping 10 as the temperature of the hydrogen piping 10 decreases.

[0045] The hydrogen piping 10 has a dual structure comprising an inner pipe 10a and an outer pipe 10b. Since a vacuum layer 10c is formed between the two pipes 10a and 10b, during periods when the vacuum level of the vacuum layer 10c is sufficient, even if liquefied hydrogen L flows inside the inner pipe 10a, the temperature of the outer pipe 10b will be maintained at a sufficiently high value relative to the temperature of the inner pipe 10a. However, the vacuum level of the vacuum layer 10c may sometimes decrease due to prolonged operation of the ship 1. When such a decrease in vacuum occurs, heat transfer between the inner pipe 10a and the outer pipe 10b is promoted, and the temperature difference between the outer pipe 10b and the inner pipe 10a is reduced. In extreme cases, the temperature of the outer pipe 10b may drop to near the temperature of the liquefied hydrogen inside the inner pipe 10a, i.e., below -253°C.

[0046] Here, as described above, the hydrogen piping 10 has a structure formed by joining multiple unit pipes 10A, and the vacuum level of the vacuum layer 10c is maintained separately for each unit pipe 10A. Therefore, the vacuum level does not decrease uniformly along the entire length of the hydrogen piping 10, but sometimes the degree of decrease varies depending on the unit pipe 10A. Thus, even if the temperature of the outer pipe 10b drops to near the temperature of liquefied hydrogen L, this phenomenon usually occurs only in one or two specific unit pipes 10A, in other words, only in a portion of the hydrogen piping 10. Based on this, the portion of the hydrogen piping 10 whose surface temperature drops to near the temperature of liquefied hydrogen L will be specifically referred to below as the temperature-dropped portion. In the case of a temperature-dropped portion in the hydrogen piping 10, the vacuum level of the vacuum layer 10c detected by a specific detector 13 among the multiple detectors 13 arranged for each unit pipe 10A deviates from the permissible range. This specific detector 13 is arranged in the unit pipe 10A corresponding to the temperature-dropped portion.

[0047] In the event of a temperature drop in the hydrogen piping 10, the crew of vessel 1 may perform repair work on the unit pipe 10A corresponding to the temperature drop section or replace it with a new unit pipe 10A. However, before such work is completed, nitrogen or oxygen in the air may condense on the surface of the outer pipe 10b in the temperature drop section of the hydrogen piping 10, potentially forming liquefied air. If this liquefied air drips down the surface of the outer pipe 10b onto the canister lid 4 located below the temperature drop section, the canister lid 4 will be significantly cooled by the liquefied air. Since the canister lid 4 is typically made of ordinary structural mild steel, it is susceptible to cryogenic embrittlement due to the temperature drop when cooled by liquefied air.

[0048] In view of this problem, in this embodiment, each storage area AR capable of storing seawater is divided on the upper side of the tank cover 4 based on the storage area dividing member 20. The control device 9 controls the seawater supply device 8 and each on / off valve 8c according to the detection results of each detector 13, so that seawater is stored in each storage area AR divided on the tank cover 4. In this state, the seawater stored in each storage area AR can reliably receive liquefied air dripping from the hydrogen pipe 10 and make it evaporate rapidly. Therefore, it is difficult for liquefied air to reach the tank cover 4 and significantly cool the tank cover 4, thus the tank cover 4 can be properly protected from the effects of low-temperature embrittlement.

[0049] Moreover, the seawater, which is a liquid that promotes evaporation of the AR stored in each storage area, is readily supplied to the ship 1 that travels at sea, and the liquefied air that drips off can be rapidly evaporated.

[0050] Furthermore, in this embodiment, the storage area dividing member 20 divides multiple storage areas AR along the pipe axis X of the hydrogen piping 10 on the upper side of the tank cover 4. Specifically, the storage area dividing member 20 divides multiple storage areas AR on the upper side of the tank cover 4 such that each storage area AR is located below each unit pipe 10A constituting the hydrogen piping 10. Here, it is assumed that, for example, a significant temperature drop occurs in a portion of the multiple unit pipes 10A, that is, a significant temperature drop occurs locally in the hydrogen piping 10 along the pipe axis X, and liquefied air forms in the temperature drop portion where the temperature drop occurs. In this case, the vacuum level of the vacuum layer 10c detected by the specific detector 13 disposed on the unit pipe 10A corresponding to the temperature drop portion deviates from the permissible range. The control device 9 controls the seawater supply device 8 by opening the on / off valve 8c disposed on the specific seawater flow auxiliary pipe 8b corresponding to the unit pipe 10A that is the temperature drop portion, and closing the other on / off valves 8c, based on the detection result of the specific detector 13.

[0051] Seawater, drawn by the operation of the seawater supply device 8 controlled by such a control device 9, flows through the main seawater flow pipe 8a and a specific secondary seawater flow pipe 8b. The seawater flowing through the secondary seawater flow pipe 8b flows into and is stored in a storage area AR connected to that secondary pipe 8b. This storage area AR is located below the unit pipe 10A corresponding to the temperature drop section. Thus, by storing the seawater in the specific storage area AR, which is divided on the upper side of the tank cover 4, liquefied air dripping from the local temperature drop section of the hydrogen pipe 10 can be reliably received and evaporated. Therefore, the tank cover 4 can be properly protected from the effects of low-temperature embrittlement.

[0052] Furthermore, in the temperature-dropped section of the hydrogen piping 10, the temperature of the outer pipe 10b drops to near the temperature of the liquefied hydrogen L. Therefore, if a support member 30 is provided in such a temperature-dropped section, the support member 30 will be significantly cooled due to heat conduction from this section. In particular, the seat portion 31 and the fixing member 33 in the support member 30 that contact the hydrogen piping 10 will be significantly cooled. If the material of the support member 30 is ordinary structural mild steel, the same as that of the can lid 4, the support member 30 may become brittle due to low-temperature embrittlement and may not be able to properly support the hydrogen piping 10. In view of this problem, in this embodiment, the material of the support member 30 is set to a low-temperature steel that is difficult to become brittle even under extremely low temperature conditions. Therefore, even if the support member 30 is significantly cooled, low-temperature embrittlement of the support member 30 can be sufficiently suppressed, and the support strength of the support member 30 for the hydrogen piping 10 can be well maintained.

[0053] The above describes the piping structure and ship for cryogenic liquids according to the embodiments of the present invention. However, the present invention is not limited thereto and can be implemented in modified embodiments such as those described below.

[0054] In the above embodiment, the storage area dividing member 20 is described as dividing multiple storage areas AR along the pipe axis X of the hydrogen pipe 10 on the upper side of the tank cover 4. However, this can also be replaced by... Figure 7 Such a storage area is divided by component 20. That is, in this... Figure 7 In a modified example, the storage area dividing member 20 divides the upper side of the tank cover 4 into a storage area AR corresponding to the entire area where the hydrogen piping 10 is laid. Therefore, even if the hydrogen piping 10 is laid out in a manner that is correspondingly curved and extended above the tank cover 4, making the piping layout complex, or even if significant temperature drops occur at multiple locations of the hydrogen piping 10, the seawater stored in the single storage area AR divided on the tank cover 4 can reliably catch and evaporate the liquefied air dripping from each temperature drop.

[0055] Furthermore, if it is known in advance that the vacuum level of the vacuum layer 10c in the hydrogen piping 10 is particularly prone to decrease, the storage area dividing member can be provided in such a way that the storage area AR is defined and divided below such a position.

[0056] In the above embodiment, the storage area dividing member 20 is exemplified as a frame-like structure formed by multiple longitudinal beams 21 and transverse beams 22, but it is not limited to such a structure. For example, the storage area dividing member 20 may also be constructed as a box-shaped container with an open top. Hereinafter, the storage area dividing member 20 constructed from such a container will be referred to as a "storage area dividing container". The storage area dividing container has: a peripheral wall, corresponding to the aforementioned longitudinal beams 21 and transverse beams 22; and a bottom wall connected to the lower end of the peripheral wall. The storage area dividing container is configured such that the bottom wall contacts the upper side of the lid 4, and the area surrounded by the peripheral wall and the bottom wall is divided as the storage area AR. Even if liquefied air drips from the hydrogen pipe 10 before storing seawater, the storage area dividing container can catch the liquefied air through the bottom wall and allow it to evaporate. Thus, it is possible to prevent liquefied air dripping from the hydrogen pipe 10 before storing seawater in the storage area AR from reaching the lid 4, and properly protect the lid 4 from the effects of low-temperature embrittlement.

[0057] Furthermore, it is ideal for the storage area partition container to be made of austenitic stainless steel or other low-temperature steel. This helps to prevent low-temperature embrittlement of the storage area partition container that may occur when liquefied air drips from the hydrogen piping 10 onto the bottom wall of the storage area partition container.

[0058] In the above embodiment, a structure is illustrated for supplying and storing seawater to each storage area AR divided on the upper side of the cover 4, but it is not limited to such a structure. For example, it could also be a structure in which a water tank for accumulating rainwater is provided on the hull 2, and water is supplied from the water tank to each storage area AR and stored.

[0059] In the above embodiment, a structure is illustrated in which the hydrogen piping 10 is installed above the tank cover 4 of the ship 1. However, the hydrogen piping 10 can be installed not only above the tank cover 4, but also above the deck 7 or inside a cargo equipment room or other interior space. Even if the hydrogen piping is installed in a location other than above the tank cover 4, the storage area dividing member 20 can be arranged in a location other than above the tank cover 4, and a support structure based on the same support member 30 as in the above embodiment can be used.

[0060] In the above embodiment, the hydrogen piping 10 is a double pipe having an inner pipe 10a and an outer pipe 10b with a vacuum layer 10c formed between them. However, a non-double structure piping without a vacuum layer can also be used as a cryogenic piping. For example, a main pipe made of cryogenic steel and an insulation layer such as a polyurethane layer formed on its outer surface can be used as the above-mentioned cryogenic piping.

[0061] In the above embodiments, an example of applying the piping structure of the present invention to a ship 1 that stores and transports liquefied hydrogen L with a boiling point of -253°C at atmospheric pressure was described; however, the present invention is not limited thereto. Any ship that can employ the piping structure of the present invention can store extremely low-temperature liquids with a boiling point of -196°C or below at atmospheric pressure. Therefore, the piping structure of the present invention can be applied to various types of ships. For example, the piping structure of the present invention can also be used on ships that store liquefied helium with a boiling point of -269°C at atmospheric pressure or liquefied nitrogen with a boiling point of -196°C at atmospheric pressure.

[0062] The above-described embodiments and variations include the following inventions.

[0063] One aspect of the present invention relates to a piping structure for cryogenic liquids, suitable for ships storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure, and comprising: cryogenic piping arranged along a structural component at a position upward relative to the structural component of the ship, allowing the cryogenic liquid to flow; and a storage area dividing member disposed on the structural component, dividing a storage area capable of storing an evaporation-promoting liquid on the structural component, wherein the evaporation-promoting liquid, in the event of liquefied air forming on the surface of the cryogenic piping, receives and evaporates the dripping liquefied air.

[0064] Cryogenic piping that allows the flow of extremely low-temperature liquids with a boiling point below -196°C at atmospheric pressure can potentially drop to temperatures close to those of the liquids, at least locally. During the significant temperature drop within the piping, nitrogen or oxygen in the air may condense on its surface, forming liquefied air. If this liquefied air drips down the surface of the piping onto structural components of a ship located below it, the components will be significantly cooled. Since ship structural components are typically made of ordinary structural mild steel, they are susceptible to cryogenic embrittlement due to the temperature drop. To address this problem, in this invention, a storage area for storing an evaporation-promoting liquid is defined on the upper side of the structural component by a storage area dividing member. With the evaporation-promoting liquid stored in the storage area on the structural component, the liquid reliably catches and evaporates the liquefied air dripping from the cryogenic piping. This prevents liquefied air from reaching the ship's structural components with a sufficiently high probability, effectively protecting the components from cryogenic embrittlement.

[0065] In the aforementioned piping structure for cryogenic liquids, the evaporation-promoting liquid can be seawater. Seawater is readily available on ships traveling at sea and can rapidly evaporate dripping liquefied air.

[0066] In the above-described piping structure for cryogenic liquids, the storage area dividing member can be configured to divide a plurality of storage areas along the pipe axis of the cryogenic piping on the structural component.

[0067] In this solution, when a significant temperature drop occurs locally in the cryogenic piping along the pipe axis, and liquefied air forms in the temperature-dropped portion, the evaporation-promoting liquid can be stored only in specific storage areas corresponding to the temperature-dropped portion within multiple storage regions designated on the structural components. In this case, the evaporation-promoting liquid stored in these specific storage areas reliably catches and evaporates the liquefied air dripping from the localized temperature-dropped portion of the cryogenic piping. This effectively protects the structural components from cryogenic embrittlement.

[0068] In the above-mentioned piping structure for cryogenic liquids, the storage area dividing member can be configured to divide one storage area on the structural component corresponding to the entire area where the cryogenic piping is laid.

[0069] In this scheme, even if the piping layout becomes complicated by being laid out in a manner that bends and extends accordingly above the structural components, or even if a significant temperature drop occurs at multiple locations in the cryogenic piping, the liquid can reliably catch and evaporate the liquefied air dripping at each temperature drop location by evaporation in a storage area divided on the structural components.

[0070] The aforementioned piping structure for cryogenic liquids may further include: a support member that supports the cryogenic piping at a position that is upwardly away from the structural component and is in contact with the cryogenic piping; wherein the support member is formed of cryogenic steel that is less prone to cryogenic embrittlement compared to the structural component.

[0071] In the event of a significant temperature drop in cryogenic piping, the supports for the piping may be significantly cooled due to heat conduction from the piping. In this situation, if the supports are made of the same material as the structural components of a ship, they may become brittle due to cryogenic embrittlement and may fail to properly support the cryogenic piping. To address this issue, the supports are made of cryogenic steel, which is less prone to cryogenic embrittlement compared to the structural components. Therefore, even if the supports are significantly cooled, cryogenic embrittlement of the supports can be effectively suppressed, and the support strength for the cryogenic piping can be well maintained.

[0072] Another aspect of the invention relates to a vessel for storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure, and includes: a hull having designated structural components; the aforementioned piping structure for cryogenic liquids; and a supply device capable of supplying the evaporation-promoting liquid to the storage area defined on the structural components by the storage area dividing member.

[0073] According to this vessel, when liquefied air forms on the surface of cryogenic piping, an evaporation-promoting liquid can be supplied from a supply device to storage areas designated on structural components. Thus, the evaporation-promoting liquid stored in the storage areas on the structural components can reliably receive and evaporate the liquefied air dripping from the cryogenic piping. Therefore, the structural components constituting the hull can be protected from cryogenic embrittlement.

[0074] The aforementioned vessel may be configured to further include: a detector for detecting an index value of liquefied air forming on the surface of the cryogenic piping; and a control device for controlling the supply device to store the evaporation-promoting liquid in the storage area if the index value detected by the detector deviates from a predetermined allowable range.

[0075] In this scheme, the likelihood of liquefied air forming on the surface of the cryogenic piping increases when the index value detected by the detector deviates from the specified allowable range. In such cases, the control device controls the supply device to supply evaporation-promoting liquid to storage areas designated on the structural components. Thus, the evaporation-promoting liquid stored in the storage areas on the structural components reliably catches and evaporates the liquefied air dripping from the cryogenic piping.

Claims

1. A piping structure for cryogenic liquids, suitable for ships storing cryogenic liquids with a boiling point below -196°C at atmospheric pressure, characterized in that... include: Cryogenic piping is laid along the structural component at a position that is above the structural component of the ship, and allows the cryogenic liquid to flow. as well as, A storage area dividing member is disposed on the structural component, and divides the structural component into a storage area capable of storing an evaporation-promoting liquid, which, in the event of liquefied air forming on the surface of the cryogenic piping, receives and evaporates the dripping liquefied air. The cryogenic piping is a multi-layered system comprising an inner tube, an outer tube, and a vacuum layer. The inner tube allows the cryogenic liquid to flow through, the outer tube is concentrically positioned outside the inner tube, and the vacuum layer is formed between the inner and outer tubes. The storage area dividing member divides the storage area on the structural component in such a way that the storage area is located below the cryogenic piping along its entire length.

2. The piping structure for cryogenic liquids according to claim 1, characterized in that, The evaporation-promoting liquid is seawater.

3. The piping structure for cryogenic liquids according to claim 1 or 2, characterized in that, The storage area dividing member divides the structural component into multiple storage areas along the pipe axis of the cryogenic piping.

4. The piping structure for cryogenic liquids according to claim 1 or 2, characterized in that, The storage area dividing component divides the structural component into one storage area corresponding to the entire area where the low-temperature piping is laid.

5. The piping structure for cryogenic liquids according to claim 1 or 2, characterized in that... Also includes: A support member supports the cryogenic piping at a position relative to the structural component, moving upwards and in contact with the cryogenic piping; wherein, The support member is made of low-temperature steel that is less prone to low-temperature embrittlement compared to the structural components.

6. A ship for storing cryogenic liquids with a boiling point below -196°C at normal pressure, characterized in that... include: The hull has designated structural components; Piping structure for cryogenic liquids as described in any one of claims 1 to 5; as well as, The supply device is capable of supplying the evaporation-promoting liquid to the storage area defined on the structural component by the storage area dividing member.

7. The ship according to claim 6, characterized in that... Also includes: A detector that detects an index value indicating the formation of liquefied air on the surface of the cryogenic piping; as well as, The control device controls the supply device to store the evaporation-promoting liquid in the storage area when the index value detected by the detector deviates from the preset allowable range.

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