CN113710951B

CN113710951B - Liquefied gas storage tank and ship

Info

Publication number: CN113710951B
Application number: CN202080029891.7A
Authority: CN
Inventors: 上田伸
Original assignee: Mitsubishi Shipbuilding Co Ltd
Current assignee: Mitsubishi Shipbuilding Co Ltd
Priority date: 2019-04-23
Filing date: 2020-02-17
Publication date: 2023-10-27
Anticipated expiration: 2040-02-17
Also published as: JP2020180620A; KR20210137551A; JP7227837B2; KR102573458B1; CN113710951A; WO2020217660A1

Abstract

The liquefied gas storage tank is provided with: a container body (60) that stores liquefied gas therein and has a design pressure that can cope with a pressure that is greater than the atmospheric pressure at a location where the container body (60) is disposed; a delivery pipe (63) which is provided over the inside and outside of the container body (60), one end of which is open in the liquid phase (L) of the liquefied gas in the container body (60), and the other end of which is disposed outside the container body (60) and forms a liquefied gas delivery flow path (64) therein; and a communication unit (65) capable of communicating the position where the gas phase (L) of the liquefied gas inside the container body (60) exists with the delivery flow path (64).

Description

Liquefied gas storage tank and ship

Technical Field

The present application relates to a liquefied gas storage tank and a ship provided with the liquefied gas storage tank.

The present application claims priority from japanese patent application No. 2019-81680, filed on 4/23 in 2019, the contents of which are incorporated herein by reference.

Background

Tanks for storing liquefied gases such as LNG and LPG are generally known. Liquefied gas stored in a tank is used as fuel in a thermal power plant or as a raw material for city gas.

In addition, a ship equipped with such a tank is also known (for example, patent document 1). A pump is provided in the tank, and liquefied gas in the tank is supplied to a host through a pipe and used as fuel for a ship.

Prior art literature

Patent document 1: japanese patent application laid-open No. 2018-176800

Disclosure of Invention

Problems to be solved by the application

However, there are cases where: for example, the tank is heated by outside air, so that the liquefied gas evaporates in the tank to raise the pressure in the tank to a pressure higher than the atmospheric pressure. In such a case, if the piping is opened in the atmosphere due to, for example, a failure in a gasket of a valve provided in the piping for taking out the liquefied gas in the tank to the outside of the tank, a welding failure in the piping, or the like, the liquefied gas is pushed out due to a pressure difference between the pressure in the tank and the atmospheric pressure, and leakage of the liquefied gas is not prevented, and a large amount of liquefied gas may leak. In particular, in a small and medium-sized tank having a large design pressure (withstand pressure), the pressure difference between the pressure in the tank and the atmospheric pressure is large, and the leakage amount of liquefied gas is large.

In addition, when the leakage amount of the liquefied gas is large, it is necessary to enlarge a drip tray for receiving the leaked liquefied gas, which causes an increase in cost.

Accordingly, the present application provides a liquefied gas storage tank and a ship capable of suppressing leakage of liquefied gas with a simple structure.

Means for solving the problems

The liquefied gas storage tank according to the first aspect of the present application includes: a container body which stores liquefied gas therein and has a design pressure which can cope with a pressure greater than an atmospheric pressure at a position where the container body is installed; a discharge pipe provided inside and outside the container body, having one end opened in the liquid phase of the liquefied gas in the container body and the other end disposed outside the container body, and forming a discharge passage for the liquefied gas therein; and a communication unit configured to communicate a position where a gas phase of the liquefied gas exists inside the container body with the delivery flow path.

In such a storage tank, if a failure occurs in the external delivery pipe of the container body, and the delivery flow path opens to the atmosphere in the middle thereof, when the pressure in the container body becomes higher than the atmospheric pressure due to evaporation of the liquefied gas, the liquid phase of the liquefied gas is pushed out to the outside of the container body and leaks due to a pressure difference between the atmospheric pressure and the pressure in the container body. In this aspect, the pressure of the delivery flow path and the pressure of the gas phase of the liquefied gas can be equalized by communicating the gas phase of the liquefied gas with the delivery flow path by the communication portion. As a result, the pressure inside the container body can be equalized with the pressure in the delivery passage, and leakage of the liquefied gas can be prevented from occurring because the liquid phase of the liquefied gas is pushed out of the container body.

In the liquefied gas storage tank, the communication portion may be a connection pipe that connects a position of the container body where the gas phase of the liquefied gas exists with the delivery pipe at an outside of the container body and forms a connection flow path therein, and the liquefied gas storage tank may further include an on-off valve that is provided in the connection pipe so as to be capable of opening and closing the connection flow path.

By providing the connection pipe as the communication portion and opening the connection passage of the connection pipe by the opening/closing valve as described above, even if a failure occurs in the external lead-out pipe of the container body and the lead-out passage is opened to the atmosphere in the middle thereof, the pressure of the lead-out passage can be equalized with the pressure of the gas phase of the liquefied gas by flowing the gas phase of the liquefied gas into the lead-out passage by the connection passage of the connection pipe. As a result, it is possible to avoid a situation in which the leakage of the liquefied gas cannot be stopped because the liquid phase of the liquefied gas is pushed out toward the outside of the container body due to a pressure difference between the atmospheric pressure and the pressure inside the container body. In addition, when the connection flow path is closed by the on-off valve and the liquid phase of the liquefied gas does not flow into the connection flow path during normal operation in which a failure occurs in the delivery pipe, the flow loss in the case of delivering the liquid phase of the liquefied gas to the outside of the container body through the delivery pipe can be reduced.

In the liquefied gas storage tank, the opening/closing valve may be a three-way valve provided so as to be switchable between a first state in which the lead-out passage is connected between the one end and the other end of the lead-out pipe and the connection passage is closed, and a second state in which the connection passage is opened by connecting the one end of the lead-out pipe and the connection passage through the lead-out passage.

In this case, the function of opening and closing the connecting passage and the function of opening and closing the outlet passage can be achieved by one three-way valve, and it is not necessary to provide a valve for opening and closing the connecting passage and a valve for opening and closing the outlet passage separately.

The liquefied gas storage tank may further include a control device that opens and closes the connection passage through the opening/closing valve, and the control device may close the connection passage through the opening/closing valve when the liquefied gas is led out from the container body through the lead-out passage.

Even when the liquefied gas leaks from the middle of the discharge passage due to a failure in the external discharge pipe of the container body, if the connection passage is opened by the opening/closing valve in normal operation, the liquid phase of the liquefied gas can be prevented from being pushed out of the container body and the leakage of the liquefied gas cannot be stopped. On the other hand, when it is necessary to discharge the liquid phase of the liquefied gas from the container body through the discharge passage, the control device closes the connection passage by the opening/closing valve, so that the flow loss in the case of discharging the liquid phase of the liquefied gas to the outside of the container body through the discharge pipe can be reduced.

In the liquefied gas storage tank, the communication portion may be a communication hole provided in the delivery pipe so as to communicate a position where the gas phase of the liquefied gas exists with the delivery flow path in the container body.

By providing the communication hole as the communication portion in this way, the gas phase of the liquefied gas in the container body can be flowed into the discharge passage by a very simple structure, and the pressure of the discharge passage can be equalized with the pressure of the gas phase of the liquefied gas. Therefore, even if a failure occurs in the external delivery pipe of the container body and the delivery channel is opened to the atmosphere, the liquid phase of the liquefied gas can be prevented from being pushed out to the outside of the container body, and leakage of the liquefied gas cannot be stopped.

The liquefied gas storage tank may further include: an atmosphere opening pipe provided in the container body and capable of communicating a position where the gas phase of the liquefied gas exists with an outside of the container body; and a valve capable of opening and closing a flow path inside the air-opening pipe.

By providing such a valve, the pressure inside the container can be reduced before the pressure inside the container body exceeds the design pressure.

A ship according to a first aspect of the present application includes the liquefied gas storage tank described above.

According to such a ship, by providing the liquefied gas storage tank, the gas phase of the liquefied gas can be introduced into the discharge flow path by the communication portion, and the pressure of the discharge flow path can be equalized with the pressure of the gas phase of the liquefied gas. As a result, even if a failure occurs in the external delivery pipe of the container body and the delivery channel is opened to the atmosphere, the liquid phase of the liquefied gas is pushed out to the outside of the container body, and leakage of the liquefied gas cannot be stopped.

Effects of the application

According to the liquefied gas storage tank and the ship described above, leakage of liquefied gas can be suppressed by a simple structure.

Drawings

Fig. 1 is a side view of a ship according to a first embodiment of the present application.

Fig. 2 is a longitudinal sectional view of a fuel tank of a ship according to a first embodiment of the present application and is an X-X sectional view in fig. 1.

Fig. 3 is a longitudinal sectional view of a fuel tank of a ship according to a second embodiment of the present application.

Fig. 4 is a longitudinal sectional view of a fuel tank of a ship according to a third embodiment of the present application.

Detailed Description

(first embodiment)

A ship 100 according to a first embodiment of the present application will be described.

As shown in fig. 1, a ship 100 according to the present embodiment is a liquefied gas carrier that carries liquefied natural gas (LNG; liquefied Natural Gas: liquefied natural gas) or liquefied petroleum gas (LPG; liquefied Petroleum Gas: liquefied petroleum gas) as liquefied gas.

As shown in fig. 1, the ship 100 includes: hull 10, bridge 20, cargo tank 30, main unit 40, and fuel tank (liquefied gas storage tank) 50.

The hull 10 has: side 11, bottom 12 and upper deck 13. The side panel 11 has a pair of left and right side outer panels 11a. The bottom 12 has a bottom outer plate 12a connecting the left and right side outer plates 11a to each other at a lower portion.

The upper deck 13 connects a pair of left and right side outer plates 11a above the bottom 12. The upper deck 13 is an weather deck extending from the bow 10a to the stern 10 b. The upper deck 13 extends in a horizontal direction. The stern 10b side of the ship 100 is lowered according to the sailing state of the ship 100, and thus the upper deck 13 itself may be inclined downward on the stern 10b side.

The hull 10 has a substantially box-like cross-sectional shape perpendicular to the fore-and-aft direction by the side 11, the bottom 12, and the upper deck 13, and a space is formed therein. The portion on the stern 10b side in the hull 10 serves as a nacelle 14. The portion of the hull 10 closer to the bow 10a than the nacelle 14 serves as a cargo space 15 defined by the nacelle 14 and the bulkhead 15 a.

The bridge 20 is provided to extend upward from the upper portion of the hull 10. The bridge 20 is provided on the stern 10b side of the upper portion of the hull 10, and above the nacelle 14. The bridge 20 is multi-layered. A control cabin 21 for controlling the ship 100 is provided at an upper floor of the bridge 20. The control cabin 21 is configured to be capable of looking forward of the ship 100 from a high position.

The cargo tanks 30 are provided in plural (three in the present embodiment) in the fore-and-aft direction within the cargo hold 15 of the hull 10. A partition wall 15b that partitions a region accommodating each cargo oil tank 30 is provided between adjacent cargo oil tanks 30.

The cargo tank 30 of the present embodiment is a square tank formed by joining flat tank wall portions to each other. In the cargo tank 30, liquefied gas (LNG or LPG) as cargo is stored in a normal pressure and low temperature state. The term "normal pressure low temperature state" refers to a state in which the liquefied state of the liquefied gas is maintained only by setting the temperature to a low temperature without pressurizing the liquefied gas. The ship 100 is provided with an unillustrated boil-off gas treatment device for maintaining the LPG in a liquefied state at a low temperature. As the vapor treatment device, a reliquefaction device is used. The reliquefaction device cools and reliquefies the evaporated gas discharged from the cargo oil tank 30 by evaporation of the liquefied gas due to external heat at the outside of the cargo oil tank 30. The gas thus liquefied is returned as liquefied gas to the cargo tank 30.

The main machine 40 is disposed in the nacelle 14 inside the hull 10. The host 40 of the present embodiment is driven by using a liquefied gas LG such as LNG or LPG as a fuel. Here, the liquefied gas LG serving as the fuel of the host computer 40 is not limited to LNG or LPG, and may be other liquefied gas fuel or the like. The propeller 41 provided below the stern 10b of the hull 10 is rotated by driving of the main machine 40.

Next, the fuel tank 50 will be described with reference to fig. 1 and 2. In the present embodiment, the fuel tank 50 is provided on the upper deck 13 via the tank support portion 51. The fuel tank 50 is provided on the upper deck 13 above the central cargo oil tank 30 among the three cargo oil tanks 30 arranged in the fore-and-aft direction, for example.

As shown in fig. 2, the fuel tank 50 includes: a container body 60 capable of storing the liquefied gas LG in a high-pressure state; a pump 62 and a delivery pipe 63 for delivering the liquefied gas LG in the container body 60 to the outside of the container body 60; and a communication portion 65 for communicating the interior of the container body 60 with the interior of the delivery pipe 63 at the exterior of the container body 60.

The container body 60 is formed of a pressure-resistant container. The design pressure (withstand pressure) of the container body 60 is greater than the head pressure of the liquefied gas LG at the liquid level position h of the container body 60. Here, the liquid level height position h represents a distance in the vertical direction from the upper end of the inner surface of the container body 60 to the liquid level of the liquefied gas LG. The head pressure per 1m of LNG is about 50 (kPa), and thus, in the case where the liquefied gas LG is LNG and the liquid level position h of the container body 60 is 2 (m), the design pressure of the container body 60 is greater than about 100 kPa. That is, the pressure in the container body 60 is a pressure sufficient to push the liquid phase L of the liquefied gas LG in the container body 60 to the upper portion of the container body 60, as a result of which the pressure in the container body 60 is greater than the atmospheric pressure, and the liquid phase L of the liquefied gas LG can be pressed out.

An atmosphere opening pipe 72 capable of communicating a position where the gas phase G of the liquefied gas LG exists with the outside of the container body 60 and a relief valve 71 capable of opening and closing a flow path inside the atmosphere opening pipe 72 are provided at an upper portion of the container body 60. The relief valve 71 is provided to be able to release the gas phase inside the container to the atmosphere before the pressure inside the container body 60 exceeds the design pressure.

The pump 62 is provided inside the container body 60, and pressurizes the liquefied gas LG inside the container body 60 to the host 40. A driving unit such as a motor for driving the pump 62 may be provided inside the container body 60 or may be provided outside the container body 60. In particular, since the liquefied gas LG stored in the container body 60 has insulation properties, there is no problem even if the driving unit is provided in the container body 60. The pump 62 is provided at the bottom 60a of the container body 60 or near the bottom 60a so as to be disposed in the liquid phase L of the liquefied gas LG stored in the lower portion of the container body 60 inside the container body 60.

The delivery pipe 63 extends in the vertical direction over the inside and outside of the container body 60. Thereby, the delivery pipe 63 extends upward from the upper portion of the container body 60. One end of the delivery pipe 63 is connected to a discharge port (not shown) of the pump 62 in the container body 60. That is, one end of the delivery pipe 63 opens into the liquid phase L of the liquefied gas LG. The other end of the delivery pipe 63 is connected to the host 40. That is, the other end of the delivery pipe 63 is disposed outside the container body 60. A delivery passage 64 through which the liquid phase L of the liquefied gas LG in the container body 60 flows and is guided to the host 40 is formed in the delivery pipe 63. In the container main body 60, a gas phase G generated by evaporation of the liquefied gas LG exists on the liquid surface of the liquid phase L of the liquefied gas LG.

In the present embodiment, the communication portion 65 is a connection pipe having a connection passage 66 therein, which can communicate a position where the gas phase G of the liquefied gas LG in the container main body 60 exists with the lead-out passage 64. The connection pipe is provided outside the container body 60, and branches from the delivery pipe 63 between the container body 60 and the host 40, and is connected to an upper portion of the container body 60 where the gas phase G exists.

The connection pipe is provided with an opening/closing valve 67 capable of opening/closing the connection passage 66. The opening/closing valve 67 is, for example, a remote operation valve, and is a three-way valve provided at a position where the connection pipe branches from the delivery pipe 63. The three-way valve is provided so as to be switchable between a first state S1 in which the lead-out flow path 64 is communicated between one end and the other end of the lead-out pipe 63 and the connection flow path 66 is closed, and a second state S2 in which the connection flow path 66 is opened by communicating one end of the lead-out pipe 63 with the connection flow path 66 via the lead-out flow path 64. For example, the three-way valve may also be a manual valve.

Here, the fuel tank 50 further includes a control device 75 for operating the opening/closing valve 67. The control device 75 has a processor or the like, and switches the first state S1 and the second state S2 of the opening/closing valve 67 based on the operation instruction. In the present embodiment, normally, the on-off valve 67 is set to the second state S2 in which the connection flow path 66 is opened, and when the liquefied gas LG is led out from the container body 60 through the lead-out flow path 64, the control device 75 sets the on-off valve 67 to the first state S1 and closes the connection flow path 66 by the on-off valve 67.

In the ship 100 according to the present embodiment described above, it is assumed that a defect occurs in the external delivery pipe 63 of the container body 60 of the fuel tank 50, and the delivery passage 64 is opened to the atmosphere in the middle thereof. The "defective condition" is a condition in which, for example, a gasket (not shown) of the on-off valve 67 as shown in section a in fig. 2 is open to the atmosphere in the middle of the delivery pipe 63 outside the container body 60, and the delivery flow path 64 is open.

When such a problem occurs, if the pressure in the container body 60 is higher than the atmospheric pressure due to the evaporation of the liquefied gas LG, the liquid phase L of the liquefied gas LG in the container body 60 is pushed out to the outside of the container body 60 by the pressure difference between the atmospheric pressure and the pressure in the container body 60, and leaks. In this embodiment, even in such a case, the gas phase G of the liquefied gas LG can be caused to flow into the guide outflow path 64 through the connection pipe as the communication portion 65, and therefore the pressure in the guide outflow path 64 can be equalized with the pressure of the gas phase G of the liquefied gas LG.

As a result, the liquid phase L of the liquefied gas LG can be prevented from being pushed out of the container body 60 at will due to the pressure difference between the atmospheric pressure and the pressure inside the container body 60, and leakage of the liquefied gas LG cannot be stopped. Therefore, it is possible to avoid the situation where the liquid phase L is continuously leaked and most or almost all of the liquefied gas LG in the container body 60 is discharged outside the container body 60. In this way, leakage of the liquefied gas LG from the tank can be suppressed by a simple structure in which the connecting pipe is provided to the container body 60. Also, a large drip tray for receiving a large amount of leaked liquefied gas LG is not required.

Even when the above-described trouble occurs in the external delivery pipe 63 of the container main body 60 and the liquefied gas LG leaks from the delivery passage 64 during the navigation of the ship 100, if the connection passage 66 is opened while the on-off valve 67 is always set to the second state S2, the connection passage 66 and the delivery passage 64 can be communicated with each other so that the pressure of the delivery passage 64 and the pressure of the gas phase G of the liquefied gas LG can be equalized. As a result, leakage of the liquefied gas LG can be suppressed. In addition, when it is necessary to supply the liquefied gas LG to the host 40 when the liquefied gas LG is to be led out from the container main body 60 through the lead-out passage 64, the control device 75 can close the connection passage 66 by bringing the on-off valve 67 into the first state S1, and therefore, it is possible to reduce the flow loss in the case of leading out the liquefied gas LG to the host 40 through the lead-out pipe 63.

Further, by providing the relief valve 71, the pressure inside the container body 60 can be reduced before the pressure inside the container body 60 exceeds the design pressure.

(second embodiment)

Next, a ship 100 according to a second embodiment of the present application will be described with reference to fig. 3. In the second embodiment described below, the same reference numerals are given to the same portions as those in the first embodiment, and duplicate description is omitted. In the ship 100 of the present embodiment, the fuel tank 80 is different from the first embodiment.

The opening/closing valve 87 of the fuel tank 80 is a remote operation valve provided in a connection pipe as the communication portion 85. The discharge pipe 63 is provided with a discharge valve 88 in addition to the opening/closing valve 67. The delivery valve 88 may open the delivery flow path 64 when it is necessary to supply the liquefied gas LG to the host 40, or may always open the delivery flow path 64. The delivery valve 88 is provided on the host 40 side of the position where the connection pipe branches from the delivery pipe 63. The on-off valve 87 may be a manual valve.

The on-off valve 87 is operated by the control device 75. In the present embodiment, normally, when the connection passage 86 of the connection pipe is opened and the liquefied gas LG is supplied to the host computer 40 through the lead-out passage 64 from the container body 60, the control device 75 actuates the opening/closing valve 87 to close the connection passage 86 by the opening/closing valve 87.

In the ship 100 according to the present embodiment described above, when the delivery pipe 63 is defective and the delivery flow path 64 is open to the atmosphere, the gas phase G of the liquefied gas LG can be introduced into the delivery flow path 64 through the connection pipe. Therefore, the pressure in the delivery passage 64 can be equalized with the pressure of the gas phase G of the liquefied gas LG. As a result, the liquid phase L can be prevented from continuously leaking from the container body 60, and the liquefied gas LG in the container body 60 can be completely discharged to the outside of the container body 60. Thus, the leakage of the liquefied gas LG can be suppressed by a simple configuration in which the connecting pipe is provided to the container body 60.

In addition, even when a failure occurs in the external lead-out pipe 63 of the container main body 60 and the liquefied gas LG leaks from the lead-out flow path 64 during the navigation of the ship 100, the leakage of the liquefied gas LG can be suppressed by always opening the connection flow path 86 by the opening/closing valve 87. When it is necessary to supply the liquefied gas LG to the host 40 through the delivery passage 64 from the container body 60, the control device 75 can actuate the opening/closing valve 87 to close the connection passage 86. This can reduce the flow loss when the liquefied gas LG is led out to the outside of the container body 60 through the lead-out pipe 63.

Further, by providing the connecting pipe and the opening/closing valve 87 only in the fuel tank which does not include the connecting pipe and the opening/closing valve 87 as the communication portion 85, leakage of the liquefied gas LG can be easily suppressed.

(third embodiment)

Next, a ship 100 according to a third embodiment of the present application will be described with reference to fig. 4. In the third embodiment described below, the same reference numerals are given to the same parts as those in the first and second embodiments, and overlapping description is omitted. The ship 100 according to the present embodiment differs from the first and second embodiments in the fuel tank 90.

The fuel tank 90 does not include the above-described connection pipe and the on-off valves 67 and 87. That is, in the present embodiment, the communication portion 95 is a communication hole provided in the delivery pipe 63 in the container body 60 so as to communicate the position where the gas phase G of the liquefied gas LG in the container body 60 exists with the delivery flow path 64.

For example, when the inner diameter of the delivery pipe 63 is 40 (mm), the diameter of the communication hole is preferably 10 (mm) or more and 20 (mm) or less.

In the ship 100 according to the present embodiment described above, the communication hole is provided as the communication portion 95, so that the gas phase G of the liquefied gas LG can be introduced into the guide outflow path 64 by a very simple structure, and the pressure in the guide outflow path 64 can be equalized with the pressure of the gas phase G of the liquefied gas LG. As a result, even if a failure occurs in the external delivery pipe 63 of the container body 60 and the delivery flow path 64 is opened to the atmosphere, the liquid phase L of the liquefied gas LG can be suppressed from being pushed out to the outside of the container body 60 due to the pressure difference between the atmospheric pressure and the pressure inside the container body 60. Therefore, the leakage of the liquefied gas LG from the container main body 60 can be prevented from being stopped by a very simple structure.

While the embodiments of the present application have been described in detail with reference to the drawings, the configurations and combinations thereof of the embodiments are examples, and the configurations may be added, omitted, substituted, and changed without departing from the spirit of the present application. In addition, the present application is not limited by the embodiments, but only by the claims.

For example, when a failure occurs in the delivery pipe 63, the leakage may be detected by a sensor, and the control device 75 may operate the opening/closing valves 67 and 87 based on the detection result of the sensor to open the connection passages 66 and 86. The control device 75 may control the relief valve 71.

The delivery pipe 63 is not limited to a pipe for supplying the liquefied gas LG to the host computer 40. For example, a sampling tube may be provided separately from a pipe for supplying the liquefied gas LG to the main unit 40. The sampling tube is a pipe for taking out the liquefied gas LG in the container body 60 for sampling.

The relief valve 71 may be an on-off valve provided in a pipe connected to a portion of the gas phase G in the container body 60.

The liquefied gas storage tank is not limited to the case of being mounted on the fuel tank 50 of the ship 100, and may be, for example, a liquefied gas storage tank provided on the ground.

Description of the reference numerals

10 … ship hull

10a … bow

10b … stern

11 … broadside

11a … outboard plate

12 … ship bottom

12a … bottom outer plate

13 … upper deck

14 … nacelle

15 … cargo hold

15a … partition wall

15b … partition wall

20 … bridge

21 … control cabin

30 … cargo oil tank

40 … host

41 … screw propeller

50. 80, 90 … fuel tank (liquefied gas storage tank)

51 … tank support

60 … container body

60a … bottom

62 … pump

63 … lead-out piping

64 … lead-out flow path

65. 85, 95 and … communicating portions

66. 86 … connecting flow path

67. 87 … on-off valve

75 … control device

71 … safety valve

72 … pipe for opening atmosphere

88 … outlet valve

100 … ship

LG … liquefied gas

L … liquid phase

G … gas phase

S1 … first State

S2 … second state.

Claims

1. A liquefied gas storage tank is provided with:

a container body that stores liquefied gas therein and has a design pressure that can cope with a pressure greater than the atmospheric pressure at a location where the container body is disposed;

a pump provided in a liquid phase of the liquefied gas stored in the lower portion of the container body;

a delivery pipe provided inside and outside the container body, one end of which is connected to the discharge port of the pump, and the other end of which is disposed outside the container body and forms a delivery passage for the liquefied gas inside;

a communication section that connects a position where the gas phase of the liquefied gas exists in the container body and the lead-out pipe to the outside of the container body, wherein the communication section is a connection pipe that forms a connection flow path inside, and is provided with an on-off valve that is provided in the connection pipe and can open and close the connection flow path, and is capable of communicating the position where the gas phase of the liquefied gas exists in the container body with the lead-out flow path;

a control unit that opens and closes the connection flow path by the opening/closing valve;

an atmosphere opening pipe provided in the container body and capable of communicating a position where the gas phase of the liquefied gas exists with an outside of the container body; a kind of electronic device with high-pressure air-conditioning system

A safety valve capable of opening and closing a flow path inside the air opening pipe, capable of opening the air phase inside the container body to the atmosphere before the internal pressure of the container body exceeds the design pressure of the container body,

the control unit opens the connection passage by the opening/closing valve when the liquefied gas is not led out from the container body through the lead-out passage,

the control unit closes the connection passage by the opening/closing valve when the liquefied gas is led out from the container body through the lead-out passage.

2. The liquefied gas storage tank as set forth in claim 1, wherein,

the opening/closing valve is a three-way valve provided so as to be switchable between a first state in which the outlet flow path is communicated between the one end and the other end of the outlet pipe and the connection flow path is closed, and a second state in which the connection flow path is opened by communicating the one end of the outlet pipe with the connection flow path via the outlet flow path.

3. A ship is provided with:

a liquefied gas storage tank as claimed in claim 1 or 2.