KR102144518B1 - Cryogenic storage system for storing liquefied hydrogen - Google Patents

Abstract

The present invention relates to a liquefied hydrogen storage apparatus which is able to manufacture an internal wall of a tank storing liquefied hydrogen by using hydrogen storage alloy, to prevent the hydrogen bromination phenomenon, to discharge the boil off gas (BOG) generated in the tank to the outside of the tank, to collect and store the BOG in a separate storage unit made by using the hydrogen storage alloy, to prevent the BOG from leaking to the outside, and to reuse the BOG. According to the present invention, the liquefied hydrogen storage apparatus comprises: a storage tank storing liquefied hydrogen; an insulation tank installed to wrap around an external side of the storage tank to store the storage tank with the liquefied nitrogen inside; a buffer unit which includes a hydrogen collection member made of hydrogen storage alloy for absorbing and storing naturally gasified hydrogen gas discharged from the storage tank, and a support member supporting the hydrogen collection member against the insulation tank; and a hydrogen discharge control unit which controls the discharge of the hydrogen gas from the storage tank to the buffer unit.

Description

Cryogenic storage system for storing liquefied hydrogen}

The present invention relates to a storage device for transporting liquefied hydrogen, and more particularly, to stably store liquefied hydrogen in cryogenic conditions in a ship transporting liquefied hydrogen, a liquefied hydrogen propulsion ship, a liquefied hydrogen transport trailer, or a hydrogen power plant. In order to minimize the natural vaporization of liquefied hydrogen due to intrusion of ambient temperature inside the tank, and to discharge the boil off gas (BOG) to the outside of the tank, it can be stored in a separate storage unit to which a hydrogen storage alloy is applied. It relates to a liquid hydrogen storage device.

Hydrogen is a fuel product composed only of water, so it not only avoids concerns about environmental pollution such as sulfur oxide (SOx), nitrogen oxide (NOx), carbon dioxide (CO2), etc., generated from conventional heavy oil, diesel, and natural gas. It is attracting attention as an eco-friendly fuel in the future because it can be generated from the water that exists most on the planet. In addition, since the breath of oil-producing countries with large reserves of fossil fuels and natural gas has a global impact, securing hydrogen production technology is known as a way to reduce dependence on energy in oil-producing countries.

However, hydrogen energy is produced by utilizing natural energy such as wind power plants and hydroelectric power plants, and eventually, it is classified as a technology intensive body requiring advanced technology. For this reason, procurement from each country through hydrogen energy carriers is indispensable, and hydrogen carriers are known to be the best way to solve the current problems. As a technology applied to a hydrogen carrier, three methods are widely used: a method of compressing hydrogen at high pressure, a method of liquefying it at -253°C and storing it as liquefied hydrogen, and a method of using a hydrogen storage alloy.

Hydrogen compressed at high pressure (high pressure hydrogen) improves volumetric efficiency, but structural safety that can withstand high pressure environments is required along with additional equipment used for compression. Liquefied hydrogen is the thermal conduction performance of the thermal insulation system to prevent the generation of boil off gas (BOG) generated when it comes into contact with the temperature of outside air and seawater, and the mechanical performance to withstand the load caused by the movement of the ship during operation. Securing is also required.

It is difficult to maintain a perfect liquid state for high-pressure hydrogen and liquefied hydrogen, so that natural vaporized gas (BOG) is continuously generated. Vaporized hydrogen can cause a fatal problem of hydrogen embrittlement on the metallic material inside the tank. When hydrogen embrittlement occurs, the mechanical strength of the inner wall metal material decreases, and the inner wall whose strength decreases cannot withstand the impact of fluid sloshing, causing a disaster that may result in leakage and hydrogen explosion, which is a structural safety problem of a hydrogen carrier or a hydrogen carrier trailer. Can cause. In addition, since vaporized hydrogen may cause economic loss as well as stability problems of the hydrogen storage container, it is necessary to appropriately treat the vaporized hydrogen gas.

Accordingly, research is being conducted on ways to discharge all of the BOG (boil off gas) generated in the tank to the outside, reuse as propulsion fuel, and re-liquefy.

However, if all BOG is discharged into the atmosphere, there is an economic loss due to the waste of hydrogen gas, and if the natural gaseous gas is to be reused as propulsion fuel, additional piping is installed, facilities are installed, and the engine is combined. There is a problem that is difficult to apply in practice due to problems, etc. In addition, the re-liquefaction method is also difficult to apply due to the low economic feasibility and practicality as many additional facilities are required.

Republic of Korea Patent Publication No. 10-2002-0058671 (published on July 12, 2002) Republic of Korea Patent Publication No. 10-2018-0095527 (published on August 27, 2018) Korean Patent Registration No. 10-1744284 (registered on May 31, 2017)

An object of the present invention is to prevent hydrogen embrittlement by making the inner wall of a tank storing liquefied hydrogen with a hydrogen storage alloy, and to discharge a boil off gas (BOG) generated in the tank to the outside of the tank It relates to a liquefied hydrogen storage device that can be reused and prevented outflow of natural vaporized gas by collecting and storing in a separate storage unit to which is applied.

Liquefied hydrogen storage device according to the present invention for achieving the above object, a storage tank for storing liquefied hydrogen; An insulating tank installed to surround the outside of the storage tank and storing liquid nitrogen in which the storage tank is contained; A buffer unit including a hydrogen collecting member made of a hydrogen storage alloy for absorbing and storing naturally vaporized hydrogen gas discharged from the storage tank, and a support member supporting the hydrogen collecting member with respect to the heat insulating tank; And a hydrogen discharge control unit for controlling discharge of hydrogen gas from the storage tank to the buffer unit.

The buffer unit may be installed on the inside of the heat insulation tank.

The support member includes an upper support member in the form of a flat plate installed so as to cross the upper portion of the heat insulating tank, and a lower support member in the form of a flat plate installed in parallel with the upper support member at a predetermined distance below the upper support member. And; The hydrogen collecting member has a flat plate shape and is supported between the upper support member and the lower support member at a predetermined distance from the upper support member and the lower support member.

Upper support ribs and lower support ribs supporting both edges of the hydrogen collecting member may be formed to protrude downward and upward, respectively, at both edge portions of the upper support member and the lower support member.

The upper and lower guide grooves into which the upper and lower support ribs are inserted are formed to extend along the longitudinal direction of the hydrogen collecting member on the upper and lower surfaces of both edges of the hydrogen collecting member, respectively, and the hydrogen collecting member When the hydrogen absorbs and expands, it expands in one direction while being guided by the upper and lower support ribs.

The liquefied hydrogen storage device of the present invention includes a bypass unit for guiding vaporized nitrogen gas to the upper side of the upper support member by connecting the upper support member and the lower support member while passing through the upper support member and the lower support member, and the heat insulation. A nitrogen discharge pipe installed in communication with the outside on the upper surface of the tank to discharge nitrogen gas guided to the upper space of the upper support member through the bypass unit to the outside, and a valve that controls the discharge of nitrogen gas through the nitrogen discharge pipe It may further include.

The bypass unit is formed to extend in a vertical direction between the upper support member and the lower support member and corresponds to a hollow tube-shaped gas guide tube having a thread formed on an inner or outer circumferential surface, and a thread of the gas guide tube. It may include a fastening member coupled to the gas guide tube from the upper side of the upper support member or the lower side of the lower support member by forming a screw portion to be helically coupled and a through hole communicating with the hollow of the gas guide tube vertically. .

The storage tank may be made of a hydrogen storage alloy.

In this case, a tank support unit may be installed between both side surfaces of the storage tank and both sides of the insulation tank to support the storage tank in an expandable manner with respect to the insulation tank.

The tank support unit includes a fixed support fixed to both sides of the insulated tank, and a fixed amount connected to the fixed support on both sides of the storage tank so as to move relative to the fixed support when the storage tank expands and contracts. It may include a movable support.

The hydrogen discharge control unit includes a hydrogen gas discharge pipe connecting the upper portion of the storage tank and the buffer unit to guide the hydrogen gas of the storage tank to the buffer unit, and hydrogen through the hydrogen gas discharge pipe while being opened or closed according to the pressure inside the storage tank. It may include a control valve for controlling the discharge of gas.

According to the present invention, in the process of storing and transporting liquefied hydrogen in a storage tank, when liquefied hydrogen is spontaneously vaporized to generate hydrogen gas, hydrogen gas is discharged to a buffer unit configured outside the storage tank to be transferred to a hydrogen collecting member made of a hydrogen storage alloy. Since it is absorbed and collected, hydrogen gas can be safely left without configuring a separate safety device for external discharge of hydrogen gas, and the pressure inside the storage tank can be kept constant during the transport process.

In addition, since cryogenic liquid nitrogen is filled outside the storage tank to provide an insulating effect, there is an effect of minimizing the natural vaporization rate of liquid hydrogen.

1 is a front cross-sectional view of a liquid hydrogen storage device according to an embodiment of the present invention.
2 is a cross-sectional view of the liquid hydrogen storage device shown in FIG. 1 as viewed from the side.
3 is a three-dimensional cross-sectional view showing the configuration of a buffer unit of the liquid hydrogen storage device shown in FIG. 1.
4 is an exploded perspective view showing the configuration of a bypass unit of the liquid hydrogen storage device shown in FIG. 1.
5 is a cross-sectional view of the bypass unit shown in FIG. 4.

The embodiments described in the present specification and the configurations shown in the drawings are only preferred examples of the disclosed invention, and there may be various modifications that may replace the embodiments and drawings of the present specification at the time of filing of the present application.

Hereinafter, a liquid hydrogen storage device will be described in detail according to embodiments described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same components.

1 to 5, a liquefied hydrogen storage device according to an embodiment of the present invention includes a storage tank 10 for storing liquefied hydrogen (LH ₂ ), and is installed to surround the outside of the storage tank 10 Insulation tank 20 in which liquefied nitrogen (LN ₂ ) is stored therein, and buffer unit 30 for absorbing and storing naturally vaporized hydrogen gas discharged from the storage tank 10 And a hydrogen discharge control part for controlling discharge of hydrogen gas from the storage tank 10 to the buffer part 30.

The storage tank 10 constitutes a container for storing cryogenic liquefied hydrogen (LH ₂ ) below -253°C, and may be made of SUS 304L, stainless steel, aluminum, etc., which are metals having excellent cryogenic resistance, but absorbs and stores hydrogen. It can be made of a hydrogen storage alloy. A hydrogen storage alloy is a material in which atomic hydrogen penetrates into a lattice in a metal crystal to form a metal hydride (MHn), and has an advantage that there is no concern about hydrogen embrittlement which reduces mechanical performance. While the density of hydrogen gas is 40g/L at room temperature 70MPa, and the density of liquid hydrogen is 70g/L at 21K and atmospheric pressure, the hydrogen density of metal hydrides is 90g/L in volume density and 1.4mass% in mass density, so 100atm As a standard, it has a hydrogen storage capacity of 15 times that of gaseous hydrogen and twice as much as liquid hydrogen, and there is no risk of explosion due to leakage of gaseous hydrogen as it enters a stable state when storing hydrogen.

When the storage tank 10 is made of a hydrogen storage alloy, the storage tank 10 expands as it absorbs hydrogen and contracts when hydrogen is released, so it is preferable that the storage tank 10 is supported so that the flow is possible with respect to the insulation tank 20.

To this end, a tank support unit is installed between both sides of the storage tank 10 and both sides of the insulation tank 20 to support the storage tank 10 in an expandable manner with respect to the insulation tank 20. In this embodiment, the tank support unit is connected to the fixed support 61 fixed to both sides of the heat insulating tank 20 and the fixed support 61 on both sides of the storage tank 10 so that a certain amount of movement is possible. It includes a movable support 62 supported while moving relative to the fixed support 61 when the storage tank 10 is expanded and contracted. Here, the fixed support 61 and the movable support 62 are made of a beam having an approximately'L'-shaped cross-section, and a portion of the fixed support 61 and the movable support 62 in contact with each other is an inclined surface. Consisting of, the movable support 62 can be stably supported without being separated from the fixed support 61 in the process of transport.

The insulating tank 20 is a substantially rectangular parallelepiped structure having a space for accommodating the storage tank 10, and liquid nitrogen (LN ₂ ) in which the storage tank 10 is contained within the space of the insulating tank 20 Is saved. Since the liquid nitrogen (LN ₂ ) surrounds the outside of the storage tank 10 while having a temperature of -192°C, it is possible to prevent the liquefied hydrogen (-253°C) in the storage tank 10 from receiving heat from the outside air. I can. However, liquid nitrogen (LN ₂₎ temperature of liquid hydrogen (LH ₂₎ storage tank (10) because of relatively high than the temperature not be completely eliminated liquefied natural vaporization of the hydrogen (LH ₂₎ in the very small amounts of However, a certain degree of natural vaporization is bound to be involved.

In order to suppress the phenomenon that the liquid nitrogen (LN ₂ ) in the insulation tank 20 is naturally evaporated by heat transfer from outside air, the insulation tank 20 is an insulation material or vacuum insulation material on the inside or surface of metal having excellent cryogenic resistance. It is preferable to have a structure that is installed.

A cover 21 is detachably installed at the upper end of the insulation tank 20. The cover 21 is detachably fixed to the upper end of the thermal insulation tank 20 by a fastening means 22 such as a known clamping mechanism, a coupling mechanism, or a bolt. The cover 21 is installed in communication with the outside to discharge nitrogen gas guided to the upper space of the buffer unit 30 to the outside, and discharge of nitrogen gas through the nitrogen discharge pipe 51 A valve 52 is installed to control it. The valve 52 may be a pressure control valve that automatically opens when the pressure in the space under the cover 21 is equal to or higher than a predetermined pressure.

Liquefied nitrogen (LN ₂ ) in the insulation tank 20 is a safe gas, and most of it is vaporized and discharged to the outside during the transportation of liquefied hydrogen, and the liquid nitrogen (LN ₂ ) in the insulation tank 20 is sloshing during the transportation process. Since this may occur, it is desirable to sufficiently submerge the upper portion of the storage tank 10 when liquid nitrogen is initially replenished.

The buffer unit 30 is installed above the heat insulating tank 20 and is configured to receive and collect the vaporized hydrogen gas through a hydrogen discharge control unit connected to the upper end of the storage tank 10. In this embodiment, the hydrogen discharge control unit is a hydrogen gas discharge pipe 41 connecting the upper portion of the storage tank 10 and the buffer unit 30 to guide hydrogen gas from the storage tank 10 to the buffer unit 30. ), and a control valve 42 that controls the discharge of hydrogen gas through the hydrogen gas discharge pipe 41 while being opened or closed according to the pressure inside the storage tank 10.

The buffer unit 30 includes a hydrogen collecting member 33 made of a hydrogen storage alloy, and an upper supporting member 31 and a lower supporting member 32 that are supporting members supporting the hydrogen collecting member 33 against the heat insulating tank. Includes.

The upper support member 31 and the lower support member 32 are made of a cryogenic metal having excellent cryogenic resistance and high strength that can sufficiently withstand the pressure of nitrogen gas and hydrogen gas vaporized in the heat insulation tank 20 . The upper support member 31 and the lower support member 32 are formed in a rectangular flat plate shape having a size corresponding to the inner space of the heat insulation tank 20 and are installed to cross the upper portion of the heat insulation tank 20 . By the upper support member 31 and the lower support member 32, the inner space of the insulating tank 20 under the buffer unit 30 forms a sealed space.

The upper support member 31 and the lower support member 32 are vertically spaced a predetermined distance apart and installed side by side. The central portion of the lower support member 32 is connected to a hydrogen gas discharge pipe 41 connected to the upper end of the storage tank 10.

The hydrogen collecting member 33 is in the form of a flat plate and is supported by a predetermined distance from the upper support member 31 and the lower support member 32 between the upper support member 31 and the lower support member 32 do. To this end, as shown in FIG. 3, upper support ribs 34 and lower portions supporting both edges of the hydrogen collecting member 33 on both edges of the upper support member 31 and the lower support member 32 Support ribs 35 are formed to protrude downward and upward, respectively. In addition, an upper guide groove (33a) and a lower guide groove (33b) into which the upper support ribs 34 and lower support ribs 35 are inserted, respectively, on the upper and lower surfaces of both edges of the hydrogen collecting member 33 are provided. It is formed so as to extend along the longitudinal direction of the hydrogen collecting member 33, and when the hydrogen collecting member 33 absorbs hydrogen and expands, it is unidirectional while being guided by the upper and lower support ribs 34 and 35. Will expand. If the hydrogen collecting member 33 is completely fixed and supported with respect to the upper support member 31 and the lower support member 32 so that relative movement is impossible, the hydrogen collecting member 33 made of a hydrogen storage alloy absorbs hydrogen gas. Thus, a phenomenon in which the hydrogen collecting member 33 is plastically deformed may occur when it expands, but the hydrogen collecting member 33 is relatively moved with respect to the upper support member 31 and the lower support member 32 as in this embodiment. When connected as possible, the hydrogen collecting member 33 can absorb hydrogen gas and expand stably.

Since the hydrogen collecting member 33 is made of a hydrogen storage alloy that absorbs and stores hydrogen, its size is determined in consideration of expansion when hydrogen is absorbed, and at this time, the hydrogen collecting member 33 expands in the longitudinal direction as well. In order to enable this, both sides of the hydrogen collecting member 33 can be moved relative to the upper support rib 34 of the upper support member 31 and the lower support rib 35 of the lower support member 32 as described above. Is connected.

Although the hydrogen collecting member 33 may be configured as a single unit, it may be configured to be divided into a plurality of each of the hydrogen holding members 33 to be expanded and deformed while absorbing hydrogen gas.

As described above, since the upper support member 31 and the lower support member 32 of the buffer unit 30 are installed to be sealed while crossing the upper portion of the heat insulation tank 20, the lower portion of the heat insulation tank 20 When liquefied nitrogen (LN ₂ ) is evaporated in, the internal pressure rises, and thus vaporized nitrogen gas must be discharged to the outside. To this end, a bypass unit 70 for discharging the nitrogen gas vaporized at the edges of the upper support member 31 and the lower support member 32 to the upper space of the buffer unit 30 is configured. The bypass unit 70 passes through the upper support member 31 and the lower support member 32 and connects the upper support member 31 and the lower support member 32 to transfer vaporized nitrogen gas to the upper support member 31. It is configured to guide to the upper side of ).

For example, as shown in Figs. 4 and 5, the bypass unit 70 is formed to extend upward on the lower support member 32 and has a hollow tube shape having a thread 71a formed on the inner circumferential surface of the gas. The guide tube 71, the threaded portion 73 helically coupled to correspond to the thread 71a of the gas guide tube 71, and the through hole 74 communicating with the hollow of the gas guide tube 71 are vertically It is formed to penetrate and includes a fastening member 72 coupled to the gas guide tube 71 from the upper side of the upper support member 31.

Therefore, the nitrogen gas naturally vaporized in the thermal insulation tank 20 passes through the hollow portion of the gas guide tube 71 and the through hole 74 of the fastening member 72 and is discharged to the upper side of the upper support member 31. , Since it can be discharged to the outside of the insulation tank 20 through the valve 52 and the nitrogen discharge pipe 51 of the cover 21, the internal pressure of the insulation tank 20 can be constantly controlled.

The liquid hydrogen storage device configured as described above operates as follows.

In the process of storing and transporting liquefied hydrogen (LH ₂ ) in the storage tank (10), since liquefied nitrogen (LN ₂ ) is filled outside the storage tank (10), heat from outside air is transferred to the liquefied hydrogen in the storage tank (10). The vaporization of liquefied hydrogen may be minimized because it does not have an effect, but even in this case, a phenomenon in which liquefied hydrogen is evaporated naturally occurs due to a temperature difference between liquid nitrogen and liquid hydrogen.

The hydrogen gas naturally vaporized in the storage tank 10 may be absorbed by the storage tank 10 itself made of a hydrogen storage alloy, but the internal pressure of the storage tank 10 increases due to the hydrogen gas that cannot be absorbed. When the pressure inside the storage tank 10 rises above a certain pressure value by the vaporized hydrogen gas, the control valve 42 is opened and the hydrogen gas inside the storage tank 10 passes through the hydrogen gas discharge pipe 41. It flows into the space between the upper support member 31 and the lower support member 32 of the buffer unit 30.

The hydrogen gas introduced into the buffer unit 30 is absorbed and collected by a hydrogen collecting member 33 made of a hydrogen storage alloy. The hydrogen collecting member 33 gradually expands while absorbing the hydrogen gas.

In this way, in the process of storing and transporting liquefied hydrogen (LH ₂ ) in the storage tank 10, when liquefied hydrogen is naturally evaporated to generate hydrogen gas, the hydrogen gas is transferred to the buffer unit 30 configured outside the storage tank 10. Since it is discharged and absorbed by the hydrogen collecting member 33 made of a hydrogen storage alloy and collected, hydrogen gas can be safely retained without configuring a separate safety device for external discharge of hydrogen gas, and the pressure inside the storage tank 10 Can be kept constant.

The hydrogen gas collected by the hydrogen collecting member 33 may be discharged and reused after arriving at a destination.

In the above, the present invention has been described in detail with reference to the embodiments, but those of ordinary skill in the art to which the present invention pertains will be able to make various substitutions, additions, and modifications within the scope not departing from the technical idea described above. It is natural, and it should be understood that such modified embodiments also belong to the protection scope of the present invention defined by the appended claims.

LH ₂ : Liquid hydrogen LN ₂ : Liquid nitrogen
10: storage tank 20: insulation tank
21: cover 30: buffer unit
31: upper support member 32: lower support member
33: hydrogen collecting member 33a: upper guide groove
33b: lower guide groove 34: upper support rib
35: lower support rib 41: hydrogen gas discharge pipe
42: control valve 51: nitrogen discharge pipe
52: valve 61: fixed support
62: movable support 70: bypass unit
71: gas guide tube 72: fastening member
73: threaded portion 74: through hole

Claims (11)

A storage tank for storing liquid hydrogen;
An insulating tank installed to surround the outside of the storage tank and storing liquid nitrogen in which the storage tank is contained;
A hydrogen collecting member made of a hydrogen storage alloy that is installed at the top of the heat insulating tank and absorbs and stores the naturally vaporized hydrogen gas discharged from the storage tank, and a support member supporting the hydrogen collecting member against the heat insulating tank A buffer unit including a; And,
A hydrogen discharge control unit for controlling the discharge of hydrogen gas from the storage tank to the buffer unit;
Including,
The support member of the buffer unit includes an upper support member in the form of a flat plate installed to cross the upper portion of the insulating tank, and a lower support member in the form of a flat plate that is installed in parallel with the upper support member at a lower side of the upper support member. Includes;
The hydrogen collecting member has a flat plate shape and is supported between the upper support member and the lower support member at a predetermined distance apart from the upper support member and the lower support member,
An upper support rib and a lower support rib supporting both edges of the hydrogen collecting member at both edge portions of the upper support member and the lower support member, respectively, to protrude downward and upward. delete delete delete The method of claim 1, wherein the upper and lower guide grooves into which the upper and lower support ribs are inserted are formed to extend along the longitudinal direction of the hydrogen collecting member on the upper and lower surfaces of both edges of the hydrogen collecting member. When the hydrogen collecting member absorbs hydrogen and expands, the liquefied hydrogen storage device expands in one direction while being guided by the upper and lower support ribs. The method of claim 1, further comprising: a bypass unit which passes through the upper support member and the lower support member and connects the upper support member and the lower support member to guide vaporized nitrogen gas to the upper side of the upper support member; A nitrogen discharge pipe installed on the surface in communication with the outside to discharge nitrogen gas guided to the upper space of the upper support member through the bypass unit, and a valve for controlling discharge of nitrogen gas through the nitrogen discharge pipe. Liquid hydrogen storage device. The gas guide tube according to claim 6, wherein the bypass unit is formed to extend in a vertical direction between the upper support member and the lower support member and has a thread formed on an inner or outer circumferential surface, and the gas guide A screw portion that is helically coupled to a thread of the tube and a through hole communicating with the hollow of the gas guide tube is formed to penetrate vertically, and is coupled to the gas guide tube from the upper side of the upper support member or the lower side of the lower support member. Liquid hydrogen storage device including a member. The liquefied hydrogen storage device of claim 1, wherein the storage tank is made of a hydrogen storage alloy. The liquefied hydrogen storage device according to claim 8, wherein a tank support unit is installed between both side surfaces of the storage tank and both sides of the insulation tank to support the storage tank in an expandable manner with respect to the insulation tank. The method of claim 9, wherein the tank support unit is connected to a fixed support fixed to both sides of the insulating tank, and a fixed amount of movement to the fixed support on both sides of the storage tank, and fixed when the storage tank is expanded or contracted. Liquefied hydrogen storage device including a movable support supported while moving relative to the support. The method of claim 1, wherein the hydrogen discharge control unit comprises: a hydrogen gas discharge pipe connecting the upper portion of the storage tank and the buffer unit to guide hydrogen gas from the storage tank to the buffer unit, and opening or closing according to the pressure inside the storage tank. Liquefied hydrogen storage device comprising a control valve for controlling the discharge of hydrogen gas through the hydrogen gas discharge pipe.

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