WO2023199428A1

WO2023199428A1 - Liquefied gas storage tank

Info

Publication number: WO2023199428A1
Application number: PCT/JP2022/017703
Authority: WO
Inventors: 宏之武田; 崇公三好; 晴彦冨永; 麻子三橋; 宏輔関; まり子高須賀
Original assignee: 川崎重工業株式会社
Priority date: 2022-04-13
Filing date: 2022-04-13
Publication date: 2023-10-19

Abstract

A tank (1) that stores a liquefied gas (LG) comprises: a tank body (3) that is provided with an inner vessel (11) forming, to the inside thereof, a storage space for the liquefied gas (LG), and an outer vessel (13) covering the inner vessel (11) and forming a space between the outer vessel (13) and the inner vessel (11), said space being filled with a gas (BG) that results from vaporization of the liquefied gas (LG); a communication passage (5) that communicates a space (15) in the inner vessel and a space (17) between the inner and outer vessels; a first valve (7) that is provided in the communication passage (5), and is set so as to open when the pressure of the space (17) between the inner and outer vessels has fallen to a prescribed value, or when the difference between said pressure and the pressure of the space (15) in the inner vessel has fallen to a prescribed value; and a second valve (9) that is provided in the communication passage (5) in series with the first valve (7), and is configured so as to be able to open and close the communication passage (5).

Description

liquefied gas storage tank

The present disclosure relates to liquefied gas storage tanks.

Conventionally, it has been proposed to use a double-shell tank that includes an inner tank and an outer tank as a tank for storing liquefied gas, such as cryogenic liquefied hydrogen. In a double-shell tank, high heat insulation can be achieved by providing a space (space between the inner and outer tanks) outside the inner tank in which the liquefied gas is stored. It is common practice to create a vacuum layer between the inner and outer tanks, but if a vacuum layer is used, it is difficult to manage in actual operation, such as maintaining the degree of vacuum when storing liquefied gas for a long period of time, and the space between the outer tank and the outer tank The level of strength required for Therefore, it has been proposed to introduce vaporized gas of liquefied gas into the space between the inner and outer tanks by, for example, making the space within the inner tank communicate with the space between the inner and outer tanks (see, for example, Patent Document 1).

International Publication No. 2020/202578

However, when introducing vaporized gas into the space between the inner and outer tanks, the pressure in the space between the outer and outer tanks increases excessively and becomes higher than the saturated vapor pressure at the temperature of the inner space, causing gas to condense near the inner tank wall. may occur. In order to prevent this, it is necessary to prevent excessive inflow of vaporized gas from the space within the inner tank to the space between the outer and outer tanks.

In order to solve the above-mentioned problems, an object of the present disclosure is to reliably block communication between the internal tank space and the space between the inner and outer tanks as necessary in a liquefied gas storage tank having a double structure. There is a particular thing.

In order to achieve the above object, the liquefied gas storage tank according to the present disclosure includes:
A tank for storing liquefied gas,
A tank body comprising: an inner tank that forms a storage space for the liquefied gas inward; and an outer tank that covers the inner tank and forms a heat insulating layer filled with the liquefied gas between the inner tank and the inner tank; ,
a communication path that communicates the space within the inner tank and the space between the inner and outer tanks;
is provided in the communication passage and is set to open when the pressure in the space between the inner and outer tanks decreases to a predetermined value, or when the difference between the pressure in the inner tank space and the pressure in the inner tank space decreases to a predetermined value. and the first valve,
a second valve provided in the communication passage in series with the first valve and configured to be able to open and close the communication passage;
Equipped with.

Any combination of at least two features disclosed in the claims and/or the specification and/or drawings is included in the present disclosure. In particular, any combination of two or more of each of the following claims is included in the present disclosure.

The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation and should not be used to define the scope of the present disclosure. The scope of the disclosure is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.
FIG. 1 is a schematic diagram showing an example of a liquefied gas storage tank according to an embodiment of the present disclosure. FIG. 2 is an enlarged schematic diagram of a part of the liquefied gas storage tank of FIG. 1 illustrating one mode of use of the tank. FIG. 2 is an enlarged schematic view of a part of the liquefied gas storage tank of FIG. 1 to show another mode of use of the tank.

Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 shows a liquefied gas storage tank (hereinafter simply referred to as "tank") 1 according to an embodiment of the present disclosure. This tank 1 includes a tank body 3 that stores liquefied gas LG, a communication passage 5, a first valve 7, and a second valve 9, which will be described later.

In the illustrated example, the tank 1 is installed on a ship S, such as a liquefied gas storage ship. Note that in this specification, the term "liquefied gas storage ship" refers to a ship that has the function of storing liquefied gas LG. The liquefied gas storage ship in this embodiment is a liquefied gas carrier. In addition to liquefied gas carriers, liquefied gas storage ships include, for example, liquefied gas fuel ships, bunkering ships that supply liquefied gas to other ships, and the like. However, the tank 1 according to the present disclosure may be installed in a liquefied gas storage facility other than a ship, such as a ground liquefied gas storage facility or a plant that uses liquefied gas.

The liquefied gas LG stored in the tank 1 is, for example, liquefied ammonia (LNH ₃ , about -33°C), liquefied petroleum gas (LPG, about -45°C), liquefied ethylene gas (LEG, about -100°C), liquefied These are natural gas (LNG, approximately -160°C), liquefied hydrogen (LH ₂ , approximately -250°C), and liquefied helium (LHe, approximately -270°C). In this embodiment, liquefied hydrogen is stored in the tank 1.

The tank 1 is configured as a double shell tank having an inner tank 11 and an outer tank 13. Specifically, the tank body 3 includes an inner tank 11 that forms a storage space (hereinafter referred to as "inner tank space") 15 for liquefied gas LG inwardly, and an inner tank 11 that covers the inner tank 11. and an outer tank 13 that forms a space (hereinafter referred to as "space between inner and outer tanks") 17 filled with vaporized gas of the liquefied gas LG. The outer peripheral surfaces of the inner tank 11 and the outer tank 13 may each be covered with a heat-insulating layer. This tank 1 is normally operated in a state in which vaporized gas of liquefied gas is sealed in a space 17 between the inner and outer tanks, which is a heat insulating layer.

In the present embodiment, the tank body 3 has a body portion 3a that is a portion that accommodates the liquefied gas LG, and a dome portion 3b that projects upward from the body portion 3a. In this example, the main body portion 3a is covered by a tank cover 23 that is a part of the hull 21 of the ship S. The top wall of the tank cover 23 is formed with an opening through which the dome portion 3b is inserted. Through the opening of the tank cover 23, the dome portion 3b protrudes above the tank cover 23, that is, is exposed.

The dome portion 3b has a cylindrical side wall 25 extending substantially vertically, and a substantially hemispherical lid 27 that closes the upper opening of the side wall 25. Various types of piping such as a plurality of transport pipes 29 for transporting (loading and unloading) the liquefied gas LG to and from the tank 1 are attached to the dome portion 3b. In addition, in the figure, only one transport pipe 29 is shown for simplification. In this embodiment, the transport pipe 29 penetrates the lid 27 of the dome portion 3b in a substantially vertical direction.

The figure shows the above-mentioned transport pipe 29 as an example of a pipe extending to the outside of the tank 1 through the dome part 3b, but such a pipe does not carry vaporized gas. Includes various types of piping such as transportation pipes.

In this embodiment, a communication path 5 is provided that communicates the inner tank space 15 with the inner and outer tank space 17. Via the communication path 5, vaporized gas BG of the liquefied gas LG generated in the inner tank space 15 is introduced into the inner and outer tank space 17 at appropriate timing. Although not shown, the gas introduction path for introducing the vaporized gas BG from an external liquefied gas source into the space 17 between the inner and outer tanks may be connected to the communication path 5 or provided independently from the communication path 5. good.

In this embodiment, when the pressure in the space 17 between the inner and outer tanks decreases to a predetermined value (hereinafter referred to as "first predetermined pressure value") on the communication path 5, or when the pressure in the inner and outer tank section 15 decreases, A first valve 7 is provided that is set to open when the difference decreases to a predetermined value (hereinafter referred to as "first predetermined pressure difference"). Specifically, in the illustrated example, the first valve 7 is a safety valve that is set to automatically open when the first predetermined pressure difference is exceeded. The first valve 7 opens when a first predetermined pressure difference is reached, and then the pressure in the space 17 between the inner and outer tanks reaches a predetermined pressure difference (hereinafter referred to as a "second predetermined pressure difference") with respect to the pressure in the inner tank space 15. It is configured to close when the pressure rises to less than the pressure difference (').

In this embodiment, a second valve 9 separate from the first valve 7 is further provided on the communication path 5 in series with the first valve 7. The second valve 9 is configured as a valve that can open and close the communication passage 5. The second valve 9 is operated to open the first valve 7 even though the pressure in the inner tank space 15 has decreased to a second predetermined pressure difference or less with respect to the pressure in the space 17 between the inner and outer tanks after the first valve 7 is opened. It is provided for the purpose of closing the communicating path 5 when the valve 7 fails to close.

Specifically, in this embodiment, the second valve 9 is configured as a remote control valve. The remote-controlled valve may be any type of valve as long as it is electrically opened and closed by a control signal, such as an electric valve, a solenoid valve, or a diaphragm-operated valve. By using a remote control valve as the second valve 9, the second valve 9 can be closed in a short time after detecting that the first valve 7 cannot be closed when it should be closed. However, the second valve 9 does not have to be a remote control valve. That is, the second valve 9 may be a valve that can be closed by direct operation.

Furthermore, in this example, the second valve 9 is provided on the primary side of the first valve 7. With this configuration, the second valve 9 is closed on the upstream side of the first valve 7, so communication between the inner tank space 15 and the inner and outer tank space 17 can be more reliably blocked. . However, the second valve 9 may be provided on the secondary side of the first valve 7. Further, in the illustrated example, only one second valve 9 is provided, but a plurality of second valves 9 may be provided. In that case, the second valve 9 may be provided on each of the primary side and the secondary side of the first valve 7. Further, a plurality of communication passages 5 and first valves 7 may be provided.

In this embodiment, a gas discharge path 31 is provided to discharge the gas in the space 17 between the inner and outer tanks to the outside of the tank 1. The gas discharge path 31 is provided with a third valve 33 that is set to open at a predetermined pressure or higher. The third valve 33 is configured as a safety valve that automatically opens at a predetermined pressure or higher. By providing the third valve 33 in the gas discharge path 31, it is possible to prevent the pressure in the space 17 between the inner and outer tanks from becoming excessive. However, the third valve 33 may be omitted.

In addition, as shown in FIG. 1, in this embodiment, the tank 1 includes an inner tank space pressure detection device 35 that detects the pressure in the inner tank space 15, and an inner tank space pressure detection device 35 that detects the pressure in the space 17 between the inner tank and the outer tank. It is provided with a space pressure detection device 37, an inner tank space temperature detection device 39 that detects the temperature of the inner tank space 15, and an inner and outer tank space temperature sensor 41 that detects the temperature of the space 17 between the inner and outer tanks. These detection devices consist of a sensor element that detects the physical quantity (pressure, temperature) to be detected, various circuits that perform necessary processing such as signal conversion processing and arithmetic processing on the acquired detected quantity, and information necessary for these processing. The device is equipped with a memory for storing the data, a power source circuit such as a power supply element such as a battery or a power supply circuit for receiving power supply from the outside, a transmission circuit for transmitting the output signal to the outside by wire or wirelessly, and the like. Note that, in addition to these detection devices, the tank 1 may be provided with various detection devices necessary for the operation of the tank 1. Furthermore, it is not essential to provide the

detection devices

35, 37, 39, and 41 exemplified above, and only those necessary for the operation of the tank 1 may be provided.

By providing the second valve 9, after the first valve 7 is opened as shown in FIG. When the pressure of the inner tank increases to a second predetermined pressure difference or less with respect to the pressure of the inner tank space 15 and the inner tank does not close even though it should be closed, or when it cannot close even if you try to close it manually, etc. If the communication passage 5 remains open, the second valve 9 is used to close the communication passage 5 as shown in FIG. 2B, and the pressure in the space 17 between the inner and outer tanks exceeds the predetermined operating pressure. It can be prevented from rising.

When the pressure in the space 17 between the inner and outer tanks increases excessively, the pressure in the space 17 between the outer and outer tanks becomes higher than the saturated vapor pressure at the temperature of the space 15 in the inner tank, and the wall surface of the inner tank 11 in the space 17 between the inner and outer tanks Gas condensation may occur nearby. In that case, phenomena such as a decrease in the heat insulation performance of the space 17 between the inner and outer tanks and condensation of gas around the outer tank 13 due to a decrease in the temperature of the outer tank 13 may occur. Further, in the case where the third valve 33 is provided in the gas exhaust path 31 of the space 17 between the inner and outer tanks as in this embodiment, if the communication path 5 remains open as shown in FIG. 2A, There is a possibility that the pressure in the space 17 between the inner and outer tanks reaches the operating pressure of the third valve 33, and the vaporized gas BG continues to be released to the outside via the third valve 33. By closing the communication path 5 using the second valve 9, such a situation can be avoided, as shown in FIG. 2B.

In this embodiment, the first valve 7 and the second valve 9 are located above the base end 3ba of the dome portion 3b, that is, the boundary between the main body portion 3a and the dome portion 3b. More specifically, in this embodiment, the first valve 7 and the second valve 9 are located on the sides of the dome portion 3b.

Specifically, in this example, a portion of the communication pipe forming the communication path 5 is exposed to the outside of the dome portion 3b from the side wall 25 of the portion of the dome portion 3b that projects upwardly of the tank cover 23. . A first valve 7 and a second valve 9 are provided in the exposed portion of the communication passage 5 located on the side of the dome portion 3b. As described above, the liquefied gas LG transport pipe 29 penetrates upward from the lid 27 of the dome portion 3b. This is to efficiently arrange piping and piping accessories such as various valves in the limited space of the dome part 3b, and to transfer the liquefied gas LG, which is the cargo of the tank 1, within the required cargo handling time. This is because it is preferable to arrange piping having a necessary pipe diameter and to simplify the structure of the piping as much as possible. In this case, by arranging the communication passage 5 and the various valves provided in the communication passage 5 on the sides of the dome portion 3b, the piping above the tank 1 can be efficiently arranged. Although it is not essential to arrange the first valve 7 and the second valve 9 in this way, it is preferable that at least one of the first valve 7 and the second valve 9 is located on the side of the dome portion 3b. .

Note that the positions where the first valve 7 and the second valve 9 are provided are not limited to the example described above. For example, one or both of the first valve 7 and the second valve 9 may be located above the dome portion 3b, or may be located below the base end 3ba of the dome portion 3b.

In this embodiment, the third valve 33 is also located above the base end 3ba of the dome portion 3b of the tank 1, specifically on the side of the dome portion 3b. However, the arrangement of the third valve 33 is not limited to this example either. Note that the arrangement of the transport pipes 29 is not limited to the illustrated example. Further, it is not essential to provide the dome portion 3b in the tank 1.

In the method of operating the tank 1 according to the present embodiment described above, when the first valve 7 is open, the second valve 9 is opened based on the pressure or temperature of at least one of the inner tank space 15 and the space 17 between the inner and outer tanks. Close. Specifically, the fact that the first valve 7 is not closed as set is detected by, for example, one or both of the inner tank space pressure detection device 35 and the inner and outer tank space pressure detection device 37 shown in FIG. The second valve 9 can be closed based on the determined pressure value. Instead of or in addition to pressure detection, the first valve 7 closes based on the temperature value detected by either or both of the inner tank space temperature detection device 39 and the outer and outer tank space temperature detection device 41. The second valve 9 may be closed after determining that the second valve 9 is not being used. In this way, the second valve can be closed at an appropriate timing by making a judgment based on at least one of the pressure and temperature of the inner tank space 15 and/or the outer and outer tank space 17.

Although FIG. 1 shows an independent double-shell tank 1 formed independently of the hull 21 as an example of the tank 1, the structure of the tank 1 is not limited to this example, and may be of any type. The tank 1 may have a multiple heat-insulating structure. For example, the tank 1 may be of a type that is formed integrally with the hull 21. Moreover, the multiple heat insulation structure of the tank 1 may be a three-layer or more structure.

According to the liquefied gas storage tank 1 according to the present embodiment described above, in addition to the first valve 7, the second valve 9, which can be closed when the first valve 7 does not close, is provided in the communication path 5. Therefore, after the first valve 7 is opened, the pressure in the space 17 between the inner and outer tanks increases until it becomes equal to or less than the second predetermined pressure difference with respect to the pressure in the inner tank space 15, and the valve 7, which should normally be closed, increases. If the communication passage 5 remains open, for example, if it does not close despite the above operation, or if it cannot be closed even if you try to close it manually, the second valve 9 is used to close the communication passage 5, and the inner and outer tanks are closed. It is possible to prevent the pressure in the interspace 17 from rising excessively beyond a predetermined operating pressure.

In the liquefied gas storage tank 1 according to the present embodiment, the second valve 9 may be a remote control valve. With this configuration, the second valve 9 can be closed in a short time after detecting that the first valve 7 cannot be closed when it should be closed.

In the liquefied gas storage tank 1 according to the present embodiment, the second valve 9 may be provided on the primary side of the first valve 7. With this configuration, the second valve 9 is closed on the upstream side of the first valve 7, so that communication between the inner tank space 15 and the inner and outer tank space 17 can be more reliably shut off.

In the liquefied gas storage tank 1 according to the present embodiment, the tank body 3 has a main body part 3a that is a part that accommodates the liquefied gas LG, and a dome part 3b that projects upward from the main body part 3a. The first valve 7 and the second valve 9 may be located above the base end 3ba of the dome portion 3b. Furthermore, at least one of the first valve 7 and the second valve 9 may be located on the side of the dome portion 3b. With this configuration, the space around the tank 1 can be efficiently utilized, including the arrangement of other piping, such as gas transportation piping provided in the tank 1.

In the liquefied gas storage tank 1 according to the present embodiment, a gas exhaust path 31 is provided for discharging the gas in the space 17 between the inner and outer tanks to the outside, and the gas exhaust path 31 is provided so that the pressure in the space 17 between the inner and outer tanks is equal to or higher than a predetermined value. It may also include a third valve 33 that is set to open when the With this configuration, it is possible to more reliably prevent the pressure in the space 17 between the inner and outer tanks from becoming excessive.

The method of operating the liquefied gas storage tank 1 according to the present embodiment is a method of operating the liquefied gas storage tank 1 described above, in which when the first valve 7 is open, the inner tank space 15 and the space between the inner and outer tanks are This includes closing the second valve 9 based on at least one of the pressure and temperature of at least one of the spaces 17. According to this configuration, the second valve can be closed at an appropriate timing by making a judgment based on at least one of the pressure and temperature of the inner tank space 15 and/or the outer and outer tank space 17.

As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, changes, or deletions can be made without departing from the spirit of the present disclosure. Accordingly, such are also included within the scope of this disclosure.

1 Liquefied gas storage tank 3 Tank body 3a Main body part 3b Dome part 3ba Base end of dome part 5 Communication passage 7 First valve 9 Second valve 11 Inner tank 13 Outer tank 15 Inner tank inner space 17 Space between inner and outer tanks BG Vaporized gas LG liquefied gas

Claims

A tank for storing liquefied gas,
an inner tank that forms a storage space for the liquefied gas inward; and an outer tank that covers the inner tank and forms a space between the inner tank and which is filled with vaporized gas of the liquefied gas. A tank body comprising;
a communication path that communicates the space within the inner tank and the space between the inner and outer tanks;
is provided in the communication passage and is set to open when the pressure in the space between the inner and outer tanks decreases to a predetermined value, or when the difference between the pressure in the inner tank space and the pressure in the inner tank space decreases to a predetermined value. and the first valve,
a second valve provided in the communication passage in series with the first valve and configured to be able to open and close the communication passage;
A liquefied gas storage tank comprising:
The liquefied gas storage tank according to claim 1, wherein the second valve is a remote control valve.
The liquefied gas storage tank according to claim 1 or 2, wherein the second valve is provided on the primary side of the first valve.
The liquefied gas storage tank according to any one of claims 1 to 3,
The tank body has a main body portion that accommodates the liquefied gas, and a dome portion that projects upward from the main body portion,
the first valve and the second valve are located above a base end of the dome portion;
Liquefied gas storage tank.
The liquefied gas storage tank according to claim 4,
at least one of the first valve and the second valve is located on a side of the dome portion;
Liquefied gas storage tank.
The liquefied gas storage tank according to any one of claims 1 to 5, further comprising:
a gas discharge path for discharging the gas in the space between the inner and outer tanks to the outside;
a third valve provided in the gas discharge path and configured to open when the pressure in the space between the inner and outer tanks exceeds a predetermined value;
A liquefied gas storage tank.
A method of operating a liquefied gas storage tank according to any one of claims 1 to 6, comprising:
closing the second valve based on at least one of the pressure and temperature of at least one of the inner tank space and the inner and outer tank space when the first valve is open;
How to operate a liquefied gas storage tank.