Piping equipment for cryogenic fluid

Abstract

This piping equipment for a cryogenic fluid includes: an inner tube to which a cryogenic fluid is supplied; an outer tube that covers a first thermal insulation region of the inner tube and forms a vacuum layer between the outer tube and the inner tube; and a cover member that covers a second thermal insulation region located downstream from the first thermal insulation region in the inner tube and has thermal insulation properties. The second thermal insulation region of the inner tube includes a large-diameter part having an inner diameter larger than the inner diameter of a small-diameter part which is at least a portion of the first thermal insulation region.

Description

Piping equipment for cryogenic fluids

[0001] The present invention relates to a cryogenic fluid piping facility through which a cryogenic fluid flows.

[0002] Cryogenic fluid piping equipment is used when transferring a cryogenic fluid. One example of such cryogenic fluid piping equipment is the piping system described in Patent Document 1. The piping system described in Patent Document 1 includes a first pipe consisting of a vacuum-insulated double pipe and a second pipe covered with a thermally insulating covering member. The piping system further includes a preheating section between the first pipe and the second pipe. The preheating section provides heat to the cryogenic fluid flowing from a first insulating region corresponding to the first pipe to a second insulating region corresponding to the second pipe. In the piping system described in Patent Document 1, the preheating section raises the temperature of the cryogenic fluid from a cryogenic temperature to a low temperature, thereby suppressing the generation of liquefied oxygen around the second pipe.

[0003] JP 2023-89737 A

[0004] The cryogenic fluid expands as it is heated in the preheating section, which increases the flow rate of the fluid. In addition, for example, the cryogenic fluid is heated by heat entering through the covering member as it flows through the second pipe. As a result, the temperature of the cryogenic fluid flowing through the second pipe also rises and expands, just as in the case where a preheating section is provided. This increases the flow rate of the fluid.

[0005] Therefore, an object of the present invention is to provide a piping facility for cryogenic fluid that can suppress an increase in the flow velocity of the fluid flowing through the second insulating region.

[0006] The piping equipment for cryogenic fluid of the present invention comprises an inner pipe through which cryogenic fluid is supplied, an outer pipe covering a first insulating region of the inner pipe and forming a vacuum layer between the inner pipe and the outer pipe, and a covering member having insulating properties that covers a second insulating region of the inner pipe located downstream of the first insulating region, wherein the inner pipe includes a large diameter portion in the second insulating region having an inner diameter larger than the inner diameter of a small diameter portion that is at least a part of the first insulating region.

[0007] According to the present invention, the inner pipe includes a large-diameter portion in the second insulating region that has an inner diameter larger than the inner diameter of the small-diameter portion that is at least a part of the first insulating region. Therefore, a larger flow rate of fluid can be passed through the large-diameter portion than through the small-diameter portion. This prevents an increase in the flow rate of the fluid passing through the second insulating region, even if the cryogenic fluid flowing from the first insulating region to the second insulating region expands due to a decrease in thermal insulation.

[0008] According to the present invention, it is possible to prevent the flow velocity of the fluid flowing through the second heat insulating region from increasing.

[0009] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

[0010] It is a cross-sectional view showing the cryogenic fluid piping facility of the first embodiment. It is a cross-sectional view showing the cryogenic fluid piping facility of the second embodiment. It is a cross-sectional view showing the cryogenic fluid piping facility of the third embodiment.

[0011] Hereinafter, first to third embodiments of cryogenic fluid piping systems (hereinafter referred to as "piping systems") 1, 1A, and 1B according to the present invention will be described with reference to the drawings. Note that the concept of directions used in the following description is used for the convenience of explanation and does not limit the orientation of the configuration of the invention to those directions. Furthermore, the piping systems 1, 1A, and 1B described below are merely one embodiment of the present invention. Therefore, the present invention is not limited to the embodiments, and additions, deletions, and modifications are possible within the scope of the invention.

[0012] <Piping Equipment> The piping equipment 1 shown in Fig. 1 is equipment for transporting cryogenic fluids such as cryogenic boil-off gases generated by evaporation of liquefied gases such as liquefied hydrogen and liquefied helium. In the present invention, "cryogenic temperature" refers to a temperature below the condensation temperature at which air is liquefied. As will be described in detail later, the temperature range of a cryogenic temperature may be below the condensation temperature of oxygen and is not limited to the above-mentioned temperature range. The cryogenic fluid may also be a liquefied gas such as liquefied hydrogen or liquefied helium.

[0013] The piping equipment 1 is provided at a shipping or receiving terminal for liquefied gas, or at a liquefied gas transport device (e.g., a tanker). The piping equipment 1 is connected to, for example, a tank (not shown) that stores liquefied gas. The liquefied gas is supplied from the tank to the piping equipment 1. In this embodiment, liquefied hydrogen is stored in the tank. In the tank, the liquefied gas evaporates, generating cryogenic boil-off gas, which is then supplied from the tank to the piping equipment 1. The cryogenic fluid is not limited to the boil-off gas generated in the tank, but may also be cryogenic boil-off gas generated from the liquefied gas during loading and unloading. The cryogenic fluid may also be a cryogenic gas other than boil-off gas or a fluid in which gas and liquid are mixed at a cryogenic temperature. The piping equipment 1 is connected to downstream equipment (not shown), such as a compression equipment or a gas storage equipment. The piping equipment 1 transports the supplied boil-off gas to the downstream equipment. The piping equipment 1 includes an inner pipe 11, an outer pipe 12, and a covering member 13. More specifically, the piping equipment 1 further includes a heating device 14 , a temperature sensor 15 , a control device 16 , and a stirring mechanism 17 .

[0014] [Inner Pipe] Cryogenic boil-off gas is supplied from a tank into the inner pipe 11. The inner pipe 11 is a cylindrical member made of, for example, stainless steel. The supplied boil-off gas flows through the inner pipe 11. The inner pipe 11 includes a first insulation region 11a and a second insulation region 11b. The two insulation regions 11a and 11b have different insulation structures around them, as described in detail later, to prevent heat input to the boil-off gas flowing through the inner pipe 11. The two insulation regions 11a and 11b are arranged in that order from the upstream side (the tank side in this embodiment) in the inner pipe 11. The two insulation regions 11a and 11b are adjacent to each other in the inner pipe 11. In this embodiment, the first insulation region 11a is a region in the inner pipe 11 upstream of the second insulation region 11b and extending to the tank, and the second insulation region 11b is a region in the inner pipe 11 downstream of the first insulation region 11a.

[0015] The inner pipe 11 also includes a small diameter portion 11c and a large diameter portion 11d. Furthermore, in this embodiment, the inner pipe 11 further includes an expanded diameter portion 11e and an enlarged diameter portion 11f. The small diameter portion 11c is at least a part of the first insulation region 11a. In this embodiment, the first insulation region 11a of the inner pipe 11 includes an expanded diameter portion 11e, as will be described in detail later, and the small diameter portion 11c is a portion of the first insulation region 11a upstream of the expanded diameter portion 11e. The large diameter portion 11d is at least a part of the second insulation region 11b. In this embodiment, the large diameter portion 11d is the entire second insulation region 11b. The large diameter portion 11d has an inner diameter r2 that is larger than the inner diameter r1 of the small diameter portion 11c. The inner diameter r2 of the large diameter portion 11d is, for example, 1.1 to 3.0 times the inner diameter r1 of the small diameter portion 11c. However, the inner diameter r2 of the large diameter portion 11d is not limited to the above-mentioned magnification, and may be any value as long as it is larger than the inner diameter r1 of the small diameter portion 11c.

[0016] The expanded diameter portion 11e is located between the small diameter portion 11c and the large diameter portion 11d. More specifically, the expanded diameter portion 11e is connected to the small diameter portion 11c on the upstream side and to the large diameter portion 11d on the downstream side via an expanded portion 11f (described later). In this embodiment, the expanded diameter portion 11e is located in the first insulating region 11a of the inner pipe 11. More specifically, the expanded diameter portion 11e is located near the upstream end of the second insulating region 11b in the first insulating region 11a. The vicinity of the upstream end of the second insulating region 11b refers to, for example, a region where the distance L from the upstream end of the second insulating region 11b is in the range of 10×r2≦L≦40×r2. The expanded diameter portion 11e increases in diameter as it progresses downstream. More specifically, the expanded diameter portion 11e is tapered. The enlarged diameter portion 11e has an upstream inner diameter equal to the inner diameter r1 of the small diameter portion 11c, and a downstream inner diameter equal to the inner diameter r2 of the large diameter portion 11d. The enlarged diameter portion 11f connects the enlarged diameter portion 11e and the large diameter portion 11d. In this embodiment, the enlarged diameter portion 11f has a diameter equal to the inner diameter r2 of the large diameter portion 11d.

[0017] [Outer Pipe] The outer pipe 12 covers the first insulating region 11a of the inner pipe 11. That is, the first insulating region 11a is the portion covered by the outer pipe 12. More specifically, the outer pipe 12 covers the small-diameter portion 11c and the expanded-diameter portion 11e of the inner pipe 11. In this embodiment, the outer pipe 12 also covers the expanded portion 11f of the inner pipe 11. Furthermore, a vacuum layer 12a is formed between the outer pipe 12 and the inner pipe 11. More specifically, the outer pipe 12 is spaced apart from the inner pipe 11 in the radial direction and is fitted to the inner pipe 11 so as to cover the entire first insulating region 11a. Furthermore, both ends of the outer pipe 12 are closed with end caps. This forms a space between the outer pipe 12 and the inner pipe 11, and the vacuum layer 12a is formed by evacuating this space. As a result, in the first heat insulating region 11 a of the inner pipe 11 , heat input from the outside of the inner pipe 11 to the inside of the inner pipe 11 is blocked.

[0018] [Covering member] The covering member 13 covers the second insulating region 11b of the inner tube 11. In this embodiment, the covering member 13 covers the large diameter portion 11d. The covering member 13 has insulating properties. The covering member 13 is made of, for example, a foamed resin having insulating properties. In this embodiment, the covering member 13 is made of PUF (polyurethane foam). However, the covering member 13 is not limited to being made of PUF, and may be made of any material as long as it has insulating properties. Note that the covering member 13 has lower insulating properties than the vacuum layer 12a. In other words, the covering member 13 inputs more heat into the boil-off gas flowing inside the inner tube 11 than the vacuum layer 12a.

[0019] [Heating Device] The heating device 14 is provided in the inner pipe 11. More specifically, the heating device 14 is provided in the first insulating region 11a of the inner pipe 11. In this embodiment, the heating device 14 is provided downstream of the expanded diameter portion 11e in the first insulating region 11a. The heating device 14 is provided, for example, in the expanded portion 11f of the inner pipe 11. The heating device 14 heats the boil-off gas flowing through the inner pipe 11. In this embodiment, the heating device 14 heats the boil-off gas to a low temperature higher than a cryogenic temperature. The low temperature is, for example, a temperature higher than the condensation temperature of air. In this embodiment, the heating device 14 is a heating gas supply device that supplies heating gas at a temperature higher than a cryogenic temperature to the inner pipe 11. The heating device 14 uses, for example, the same type of gas as the boil-off gas. The heating device 14 also supplies room-temperature heating gas (heating hydrogen gas in this embodiment) to the expanded portion 11f of the inner pipe 11. As a result, the heating device 14 heats the boil-off gas to a temperature higher than the cryogenic temperature. Note that "room temperature" is, for example, between 5°C and 35°C, and is, for example, a temperature similar to atmospheric temperature. However, the temperature of the heating hydrogen gas supplied by the heating device 14 is not limited to room temperature, and may be less than 5°C or more than 35°C, as long as it is a temperature that can heat the cryogenic boil-off gas. More specifically, the heating device 14 includes a supply pipe 21 and a control valve 22.

[0020] The supply pipe 21 is connected to the inner pipe 11. More specifically, the supply pipe 21 is connected to the first insulation region 11a of the inner pipe 11, downstream of the expanded diameter portion 11e. In this embodiment, the supply pipe 21 is connected to the expanded portion 11f of the inner pipe 11. The supply pipe 21 is also connected to a gas supply source (not shown). The gas supply source supplies heating hydrogen gas to the supply pipe 21. In this embodiment, the gas supply source is a gas tank that stores hydrogen gas at or near room temperature. The gas tank is, for example, a boil-off gas tank (abbreviated as BOG tank) that stores boil-off gas heated by the heating device 14. Note that the gas supply source is not limited to the BOG tank described above and may be a hydrogen gas generator or other equipment capable of supplying hydrogen gas. The supply pipe 21 guides the heating hydrogen gas to the first insulation region 11a of the inner pipe 11 and merges it with the boil-off gas flowing through the first insulation region 11a. This heats the boil-off gas flowing through the first insulation region 11 a. The supply pipe 21 may be connected to the second insulation region 11 b of the inner pipe 11. In this case, the boil-off gas flowing through the second insulation region 11 b may be supplied to the supply pipe 21 as heating hydrogen gas.

[0021] The control valve 22 is provided in the supply pipe 21. The control valve 22 adjusts the opening of the supply pipe 21. More specifically, the control valve 22 adjusts the opening based on a control signal from the control device 16, which will be described in detail later. In this way, the control valve 22 controls the flow rate of the heated gas guided from the supply pipe 21 to the first insulating region 11a of the inner pipe 11 to a flow rate according to the control signal.

[0022] [Temperature Sensor] The temperature sensor 15 measures the temperature inside the inner pipe 11. The temperature sensor 15 is provided downstream of the expanded diameter portion 11e in the first insulating region 11a of the inner pipe 11. In this embodiment, the temperature sensor 15 is provided in the expanded diameter portion 11f and measures the temperature of the boil-off gas passing through the expanded diameter portion 11f.

[0023] [Control Device] The control device 16 controls the heating device 14 based on the temperature measured by the temperature sensor 15. The control device 16 acquires the temperature measured by the temperature sensor 15. The control device 16 then outputs a control signal to the heating device 14 based on the acquired temperature. In this embodiment, the control device 16 outputs a control signal to the control valve 22. This causes the control device 16 to control the aperture of the control valve 22. In other words, the control device 16 controls the aperture of the control valve 22 based on the acquired temperature. In this embodiment, the control device 16 controls the aperture of the control valve 22 so that the acquired temperature is equal to or higher than a predetermined temperature. The predetermined temperature is, for example, the condensation temperature of air. However, the predetermined temperature may also be the condensation temperature of oxygen.

[0024] [Stirring Mechanism] The stirring mechanism 17 is provided in the inner pipe 11 and downstream of the heating device 14. In this embodiment, the stirring mechanism 17 is provided in the first insulating region 11a in the inner pipe 11, for example, in the expanded portion 11f. The stirring mechanism 17 stirs the boil-off gas and the heating hydrogen gas in the inner pipe 11. This makes it possible to make the temperature distribution of the boil-off gas flowing downstream of the heating device 14 in the inner pipe 11 uniform. The stirring mechanism 17 is, for example, a static mixer. However, the stirring mechanism 17 is not limited to a static mixer and may be a fin, a filter, or the like, as long as it is capable of stirring the boil-off gas and the heating hydrogen gas.

[0025] [Flow of Boil-Off Gas in the Piping Equipment] As described above, the piping equipment 1 is connected to a tank (not shown) that stores liquefied hydrogen. Cryogenic boil-off gas is generated in the tank and supplied to the piping equipment 1. In the piping equipment 1, the cryogenic boil-off gas is supplied from the tank to the first insulation region 11a of the inner pipe 11. The first insulation region 11a of the inner pipe 11 is vacuum insulated by the vacuum layer 12a. Therefore, in the first insulation region 11a, the temperature of the boil-off gas is maintained at a cryogenic temperature by vacuum insulation. The boil-off gas maintained at a cryogenic temperature is guided to the expansion region 11f through the expansion region 11e. In the first insulation region 11a, the inner diameter of the inner pipe 11 is expanded by the expansion region 11e. Therefore, a large flow rate of boil-off gas can flow in the expansion region 11f and the second insulation region 11b. In the second insulation region 11b, the boil-off gas expands due to the heat entering through the covering member 13. However, since the inner diameter of the inner pipe 11 is expanded, a large flow rate of the boil-off gas can be allowed to flow in the second insulation region 11b. Therefore, an increase in the flow velocity of the boil-off gas in the second insulation region 11b can be suppressed.

[0026] In the inner pipe 11, the boil-off gas is heated by the heating device 14 downstream of the expanded diameter portion 11e (expanded portion 11f in this embodiment). More specifically, the heating device 14 supplies room-temperature hydrogen gas as a heating gas to the cryogenic boil-off gas at the expanded portion 11f to join the two. The stirring mechanism 17 mixes the cryogenic boil-off gas with the room-temperature boil-off gas. Thus, the boil-off gas is heated by joining the room-temperature heating gas. The temperature sensor 15 measures the temperature of the boil-off gas. The control device 16 controls the aperture of the control valve 22 based on the measured temperature measured by the temperature sensor 15. More specifically, the control device 16 controls the aperture of the control valve 22 so that the measured temperature is low, i.e., controls the amount of room-temperature boil-off gas supplied. As a result, the temperature of the boil-off gas rises from an extremely low temperature to a low temperature in the first insulation region 11a (more specifically, the expansion region 11f). The boil-off gas is then transferred from the expansion region 11f to the second insulation region 11b. That is, the boil-off gas is transferred from the first insulation region 11a to the second insulation region 11b. Therefore, the temperature of the boil-off gas flowing through the second insulation region 11b can be lowered. This prevents liquefied air from being generated around the outer circumferential surface of the second insulation region 11b of the inner tube 11.

[0027] On the other hand, boil-off gas expands as its temperature rises from cryogenic to low temperatures. This increases the flow rate of the boil-off gas in the second insulation region 11b. Furthermore, when cryogenic boil-off gas is heated, room-temperature boil-off gas joins with it, increasing the flow rate of the gas flowing through the inner tube 11. This also increases the flow rate of the boil-off gas in the second insulation region 11b. Meanwhile, in the second insulation region 11b of the inner tube 11, the inner diameter of the inner tube 11 is expanded by the expanded diameter portion 11e, resulting in an inner diameter r2 that is larger than the inner diameter r1 of the first insulation region 11a. Therefore, a larger flow rate of boil-off gas can flow in the second insulation region 11b, thereby suppressing the increase in the flow rate of the boil-off gas due to the expansion and increase in the flow rate of the boil-off gas.

[0028] In this embodiment, the heating device 14 is provided in the expanded portion 11f downstream of the expanded diameter portion 11e in the inner pipe 11. Therefore, the flow velocity of the boil-off gas can be reduced before the heating gas is supplied to the boil-off gas by the heating device 14. This makes it possible to prevent the boil-off gas from flowing at a high velocity in the inner pipe 11 after the heating gas is supplied to the boil-off gas by the heating device 14.

[0029] In the piping equipment 1 of this embodiment, the inner pipe 11 includes a large-diameter portion 11d in the second insulation region 11b, which has an inner diameter r2 larger than the inner diameter r1 of the small-diameter portion 11c in the first insulation region 11a. Therefore, a larger flow rate of fluid can flow through the large-diameter portion 11d than through the small-diameter portion 11c. This prevents the flow velocity of the boil-off gas flowing through the second insulation region 11b from increasing even if the cryogenic boil-off gas flowing from the first insulation region 11a to the second insulation region 11b expands due to a decrease in thermal insulation. This prevents, for example, an increase in the pressure loss of the boil-off gas due to an increase in the flow velocity, which in turn prevents a decrease in the flow rate of the boil-off gas. Furthermore, noise and pipe vibrations caused by an increase in the flow velocity can be suppressed.

[0030] In the piping equipment 1 of this embodiment, the inner pipe 11 includes an expanding diameter portion 11e located between the small diameter portion 11c and the large diameter portion 11d, and the expanding diameter portion 11e expands downstream, allowing the cryogenic boil-off gas to flow smoothly from the small diameter portion 11c to the large diameter portion 11d.

[0031] In the piping equipment 1 of this embodiment, the expanded diameter portion 11e is located in the first insulating region 11a of the inner pipe 11. Therefore, the inner diameter r1 of the inner pipe 11 is expanded before the cryogenic boil-off gas is heated by heat input in the second insulating region 11b of the inner pipe 11. This makes it possible to slow down the velocity of the cryogenic boil-off gas before it expands. This makes it possible to prevent the boil-off gas from flowing through the inner pipe 11 at a high velocity.

[0032] The piping equipment 1 of this embodiment further includes a heating device 14 that is provided in the inner pipe 11 and heats the cryogenic boil-off gas flowing in the inner pipe 11. This makes it possible to prevent the cryogenic boil-off gas from flowing in the second insulation region 11b of the inner pipe 11. This makes it possible to prevent liquefied air from being generated around the second insulation region 11b of the inner pipe 11.

[0033] In the piping equipment 1 of this embodiment, the heating device 14 is provided downstream of the expanded diameter portion 11e of the inner pipe 11. Therefore, the inner diameter of the inner pipe 11 is expanded before the cryogenic boil-off gas is heated, so that the velocity of the cryogenic boil-off gas can be reduced before heating. This makes it possible to prevent the boil-off gas from flowing through the inner pipe 11 at a high velocity.

[0034] In the piping equipment 1 of this embodiment, the heating device 14 is a heating gas supply device that supplies heating hydrogen gas having a temperature higher than that of the cryogenic boil-off gas to the inner pipe 11. Therefore, the cryogenic boil-off gas can be heated with a simple configuration.

[0035] Furthermore, in the piping equipment 1 of this embodiment, the control device 16 controls the heating device 14 based on the temperature measured by the temperature sensor 15. Therefore, the temperature of the fluid flowing in the inner pipe 11 can be appropriately controlled.

[0036] Furthermore, in the piping equipment 1 of this embodiment, the heating device 14 includes a supply pipe 21 and a control valve 22, and the control device 16 controls the opening degree of the control valve 22 based on the temperature measured by the temperature sensor 15. Therefore, it is easy to appropriately control the temperature of the fluid flowing in the inner pipe 11.

[0037] Furthermore, in the piping equipment 1 of this embodiment, the temperature sensor 15 is provided in the first insulation region 11a of the inner pipe 11, downstream of the heating device 14. This makes it possible to control the temperature of the boil-off gas flowing through the second insulation region 11b in the inner pipe 11. As a result, for example, by controlling the temperature of the second insulation region 11b of the inner pipe 11, it is possible to suppress the generation of liquefied air around the second insulation region 11b of the inner pipe 11.

[0038] <Second embodiment> The piping equipment 1A of the second embodiment has a similar configuration to the piping equipment 1 of the first embodiment. Therefore, with regard to the configuration of the piping equipment 1A of the second embodiment, differences from the piping equipment 1 of the first embodiment will be mainly described, and the same components will be assigned the same reference numerals and descriptions thereof will be omitted. The same applies to the piping equipment 1B of the third embodiment described later.

[0039] 2 further includes an inner pipe 11A, an outer pipe 12, a covering member 13, a heating device 14, a temperature sensor 15, and a control device 16. The inner pipe 11A further includes a small diameter portion 11Ac, a large diameter portion 11Ad, and an expanded diameter portion 11Ae.

[0040] In this embodiment, the small diameter portion 11Ac constitutes the entire first heat insulating region 11a. The large diameter portion 11Ad constitutes at least a portion of the second heat insulating region 11b, and is located downstream of the expanded diameter portion 11Ae, which will be described in detail later. As in the first embodiment, the large diameter portion 11Ad has an inner diameter r2 that is larger than the inner diameter r1 of the small diameter portion 11Ac.

[0041] The expanded diameter portion 11Ae is located in the second insulating region 11b of the inner pipe 11, between the small diameter portion 11Ac and the large diameter portion 11Ad. The expanded diameter portion 11Ae is also tapered so that its diameter increases downstream. The upstream inner diameter of the expanded diameter portion 11Ae is the same as the inner diameter r1 of the small diameter portion 11Ac, and the downstream inner diameter is the same as the inner diameter r2 of the large diameter portion 11Ad. The inner pipe 11 includes a connecting portion 11g in the second insulating region 11b, which has the same diameter as the small diameter portion 11Ac. That is, the connecting portion 11g is covered with a covering member 13. The expanded diameter portion 11Ae is connected to the small diameter portion 11Ac via the connecting portion 11g.

[0042] The heating device 14 is provided in the first insulation region 11a of the inner pipe 11. The heating device 14 supplies heating gas to the first insulation region 11a (in this embodiment, the small diameter portion 11Ac) of the inner pipe 11. The temperature sensor 15 is provided in the second insulation region 11b downstream of the expanded diameter portion 11Ae. In this embodiment, the temperature sensor 15 is provided in the large diameter portion 11Ad and measures the temperature of the boil-off gas passing through the large diameter portion 11Ad.

[0043] In the piping equipment 1A, the heating device 14 supplies room-temperature boil-off gas to the small-diameter portion 11Ac. Therefore, in the small-diameter portion 11Ac, the flow rate of the boil-off gas increases and the boil-off gas expands. Therefore, the flow velocity of the boil-off gas increases in the small-diameter portion 11Ac downstream of the heating device 14. On the other hand, in the inner pipe 11A, the inner diameter r2 of the large-diameter portion 11Ad is larger than the inner diameter r1 of the small-diameter portion 11Ac, so the flow velocity of the boil-off gas decreases in the large-diameter portion 11Ad. This prevents the flow velocity of the boil-off gas from increasing in the large-diameter portion 11Ad of the second insulating region 11b.

[0044] A temperature sensor 15 is provided in the large-diameter portion 11Ad to measure the temperature of the boil-off gas passing through the large-diameter portion 11Ad. The control device 16 controls the aperture of the control valve 22 based on the measured temperature, thereby raising the temperature of the boil-off gas flowing through the large-diameter portion 11Ad to a low temperature. This prevents liquefied air from being generated around the second insulating region 11b.

[0045] In addition, the piping equipment 1A of the second embodiment has the same effects as the piping equipment 1 of the first embodiment.

[0046] Third Embodiment The piping equipment 1B of the third embodiment shown in FIG. 3 further includes an inner pipe 11B, an outer pipe 12, a covering member 13, a heating device 14B, a temperature sensor 15, and a control device 16. The inner pipe 11B further includes a small-diameter portion 11c, a large-diameter portion 11d, an expanded-diameter portion 11e, and an enlarged portion 11f. In addition to the first and second insulating regions 11a and 11b, the inner pipe 11B also includes a heating region 11h. The heating region 11h is disposed between the first and second insulating regions 11a and 11b. In this embodiment, the inner diameter of the heating region 11h is the same as the inner diameter r2 of the expanded portion 11f and the large-diameter portion 11d, and the heating region 11h is connected to the expanded portion 11f and the large-diameter portion 11d, respectively. The heating region 11h is provided with a heating device 14B, which will be described in detail later. A temperature sensor 15 is also provided in the heating region 11h to measure the temperature of the boil-off gas passing through the heating region 11h.

[0047] The heating device 14B includes a heating wire wound in a coil shape around the heating region 11h. The control device 16 applies current to the heating wire to heat the boil-off gas through the heating region 11h. The control device 16 also controls the current or voltage applied to the heating wire based on the temperature measured by the temperature sensor 15, thereby raising the temperature of the boil-off gas flowing through the second insulation region 11b from an extremely low temperature to a low temperature. This makes it possible to prevent liquefied air from being generated around the second insulation region 11b.

[0048] In addition, the piping equipment 1B of the third embodiment has the same effects as the piping equipment 1 of the first embodiment.

[0049] <Other Embodiments> In the inner pipes 11, 11A, 11B of the piping equipment 1, 1A, 1B of the first to third embodiments, the expanded diameter portion 11e is disposed between the small diameter portion 11c and the large diameter portion 11d. However, a buffer space may be formed instead of the expanded diameter portion 11e. The buffer space has a cross-sectional area larger than that of the large diameter portion 11d, and allows the flow rate of the boil-off gas to be reset once before it flows into the large diameter portion 11d. Furthermore, the inner pipes 11, 11A, 11B of the piping equipment 1, 1A, 1B may have both the expanded diameter portion 11e and the buffer space. Furthermore, the small diameter portion 11c of the first insulation region 11a simply refers to a portion having an inner diameter r1 smaller than that of the large diameter portion 11d of the second insulation region 11b. The same applies to the large diameter portion 11d of the second insulation region 11b.

[0050] The enlarged diameter portions 11e, 11Ae of the piping equipment 1, 1A, and 1B of the first to third embodiments are formed in a single-step tapered shape, but may be formed in a multi-step tapered shape. Furthermore, the enlarged diameter portions 11e, 11Ae are not limited to the linear tapered shape shown in FIGS. 1 to 3 and may be curved tapered shapes. Furthermore, in the piping equipment 1B of the third embodiment, the enlarged diameter portions 11e, 11Ae are located in the insulating regions 11a, 11b, but may also be located in the heating region 11h, for example, as long as they are located between the small diameter portion 11c and the large diameter portion 11d. Furthermore, the heating region 11h may be positioned so as to span the two insulating regions 11a, 11b.

[0051] Furthermore, the heating devices 14, 14B of the piping equipment 1, 1A, 1B of the first to third embodiments are not limited to the devices described above, and may be fins, heat-absorbing materials, or the like, as long as they are configured to heat the boil-off gas flowing inside the inner pipe 11. Furthermore, the heating device 14B is provided directly on the outer circumferential surface of the inner pipe 11, but may also be provided inside or on the outer circumferential surface of the covering member 13.

[0052] Furthermore, in the piping equipment 1, 1A, and 1B of the first to third embodiments, the temperature sensor 15 is provided downstream of the heating device 14, 14B, but it may also be provided upstream of the heating device 14, 14B. In this case, the control device 16 performs feedforward control rather than the feedback control described above. Furthermore, the stirring mechanism 17 may also be applied to the piping equipment 1A and 1B of the second and third embodiments, and is not necessarily required in the piping equipment 1 of the first embodiment.

[0053] Furthermore, in the piping equipment 1, 1A, and 1B of the first to third embodiments, "extremely low temperature" is defined as, for example, a temperature below the condensation temperature of air, and "low temperature" is defined as, for example, a temperature higher than the condensation temperature of air. However, "extremely low temperature" and "low temperature" may be defined by the condensation temperature of oxygen instead of the condensation temperature of air. This allows the piping equipment 1, 1A, and 1B of the first to third embodiments to suppress liquefaction of oxygen around the outer peripheral surface of the second insulating region 11b of the inner pipe 11.

[0054] <Illustrative embodiment> In a first aspect, a piping facility for cryogenic fluid includes an inner pipe through which a cryogenic fluid is supplied, an outer pipe that covers a first insulating region of the inner pipe and forms a vacuum layer between the inner pipe and the outer pipe, and a covering member having insulating properties that covers a second insulating region of the inner pipe that is located downstream of the first insulating region, and the inner pipe includes a large diameter portion in the second insulating region that has an inner diameter larger than the inner diameter of a small diameter portion that is at least a part of the first insulating region.

[0055] According to the above aspect, the inner pipe includes, in the second insulation region, a large-diameter portion having an inner diameter larger than the inner diameter of the small-diameter portion that is at least a part of the first insulation region. Therefore, a larger flow rate of fluid can be made to flow in the large-diameter portion than in the small-diameter portion. This makes it possible to prevent an increase in the flow rate of the fluid flowing through the second insulation region, even if the cryogenic fluid flowing from the first insulation region to the second insulation region expands as the thermal insulation property decreases.

[0056] In a second aspect of the cryogenic fluid piping equipment, in the cryogenic fluid piping equipment of the first aspect, the inner pipe is located between the small diameter portion and the large diameter portion and includes an expanding diameter portion that expands in diameter as it proceeds downstream.

[0057] According to the above aspect, the inner pipe includes a diameter expanding portion located between the small diameter portion and the large diameter portion, the diameter of which expands downstream, thereby allowing the cryogenic fluid to flow smoothly from the small diameter portion to the large diameter portion.

[0058] In a third aspect, in the cryogenic fluid piping facility of the second aspect, the expanded diameter portion is located in the first heat insulating region of the inner pipe.

[0059] According to the above aspect, the expanded diameter portion is located in the first heat insulating region of the inner pipe, and therefore the inner diameter of the inner pipe is expanded before the cryogenic fluid is heated by heat input in the second heat insulating region of the inner pipe, so that the flow velocity of the cryogenic fluid can be reduced in advance before the cryogenic fluid expands.

[0060] In a fourth aspect, the cryogenic fluid piping facility of the second aspect further includes a heating device provided in the inner pipe for heating the fluid flowing through the inner pipe.

[0061] According to the above aspect, the apparatus further includes a heating device provided in the inner pipe for heating the cryogenic fluid flowing through the inner pipe. This makes it possible to prevent the cryogenic fluid from flowing in the second heat insulating region of the inner pipe. This makes it possible to prevent liquefied air from being generated around the second heat insulating region of the inner pipe.

[0062] In a fifth aspect, in the cryogenic fluid piping system of the fourth aspect, the heating device is provided in the inner pipe downstream of the expanded diameter portion.

[0063] According to the above aspect, the heating device is provided downstream of the expanded diameter portion of the inner pipe. Therefore, the inner diameter of the inner pipe is expanded before the cryogenic fluid is heated, so the velocity of the cryogenic fluid can be reduced before heating. This makes it possible to prevent the fluid from flowing at a high velocity through the inner pipe 11.

[0064] In a sixth aspect, in the cryogenic fluid piping facility of the fourth or fifth aspect, the heating device is a heating gas supply device that supplies a heating gas at a temperature higher than the cryogenic temperature to the inner pipe.

[0065] According to the above aspect, the heating device is a heating gas supply device that supplies a heating gas having a temperature higher than that of the cryogenic fluid to the inner tube, and therefore the cryogenic fluid can be heated with a simple configuration.

[0066] In a seventh aspect, the cryogenic fluid piping equipment is the cryogenic fluid piping equipment of any of the fourth to sixth aspects, and further comprises a temperature sensor that measures the temperature inside the inner pipe, and a control device that controls the heating device based on the temperature measured by the temperature sensor.

[0067] According to the above aspect, the control device controls the heating device based on the temperature measured by the temperature sensor, so that the temperature of the fluid flowing through the inner pipe can be appropriately controlled.

[0068] In an eighth aspect of the cryogenic fluid piping equipment, in the cryogenic fluid piping equipment of the seventh aspect, the heating device includes a supply pipe connected to the inner pipe and a control valve provided on the supply pipe, and the control device controls the opening degree of the control valve based on the temperature measured by the temperature sensor.

[0069] According to the above aspect, the heating device includes a supply pipe and a control valve, and the control device controls the opening degree of the control valve based on the temperature measured by the temperature sensor. Therefore, it is easy to appropriately control the temperature of the fluid flowing through the inner pipe.

[0070] In a ninth aspect, in the piping equipment for cryogenic fluid of the seventh or eighth aspect, the temperature sensor is provided in the first insulating region of the inner pipe, downstream of the heating device.

[0071] According to the above aspect, the temperature sensor is provided in the first insulating region of the inner pipe downstream of the heating device. Therefore, the temperature of the fluid flowing in the second insulating region within the inner pipe can be controlled. Thus, for example, by controlling the temperature of the second insulating region of the inner pipe, it is possible to suppress the generation of liquefied air around the second insulating region of the inner pipe.

[0072] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention.

[0073] 1, 1A, 1B Piping equipment 11, 11A, 11B Inner pipe 11a First insulation area 11b Second insulation area 11c, 11Ac Small diameter portion 11d, 11Ad Large diameter portion 11e, 11Ae Expanded diameter portion 12 Outer pipe 12a Vacuum layer 13 Covering member 14, 14B Heating device 15 Temperature sensor 16 Control device 21 Supply pipe 22 Control valve r1 Inner diameter r2 Inner diameter

Claims

1. Piping equipment for cryogenic fluid, comprising: an inner pipe through which a cryogenic fluid is supplied; an outer pipe covering a first insulating region of the inner pipe and forming a vacuum layer between the inner pipe and the outer pipe; and a covering member having insulating properties covering a second insulating region of the inner pipe located downstream of the first insulating region, wherein the inner pipe includes, in the second insulating region, a large diameter portion having an inner diameter larger than the inner diameter of a small diameter portion that is at least a part of the first insulating region.

2. Piping equipment for cryogenic fluids as described in claim 1, wherein the inner pipe is located between the small diameter portion and the large diameter portion and includes an expanding diameter portion that expands in diameter as it proceeds downstream.

3. The cryogenic fluid piping facility according to claim 2, wherein the expanded diameter portion is located in the first insulating region of the inner pipe.

4. The cryogenic fluid piping facility according to claim 2, further comprising a heating device provided in said inner pipe for heating the fluid flowing through said inner pipe.

5. The piping facility for cryogenic fluids according to claim 4, wherein the heating device is provided downstream of the expanded diameter portion in the inner pipe.

6. The piping facility for cryogenic fluids according to claim 4, wherein the heating device is a heating gas supply device that supplies a heating gas having a temperature higher than the cryogenic temperature to the inner pipe.

7. The piping facility for cryogenic fluids according to claim 4, further comprising: a temperature sensor for measuring the temperature inside the inner pipe; and a control device for controlling the heating device based on the temperature measured by the temperature sensor.

8. Piping equipment for cryogenic fluids as described in claim 7, wherein the heating device includes a supply pipe connected to the inner pipe and a control valve provided in the supply pipe, and the control device controls the opening degree of the control valve based on the temperature measured by the temperature sensor.

9. The cryogenic fluid piping installation according to claim 7, wherein the temperature sensor is provided in the first insulating region of the inner pipe downstream of the heating device.

Images