KR20200103404A - System for storing liquefied hydrogen and collecting boil-off hydrogen - Google Patents

Abstract

The present invention relates to a system for storing liquefied hydrogen and collecting boil-off hydrogen which prevents hydrogen embrittlement by making an inner wall of a tank for storing liquefied hydrogen out of a hydrogen storage alloy, and discharges natural boil-off gas (BOG) created in the tank out of the tank to collect and store the natural boil-off gas in a separate hydrogen collection unit to which a hydrogen storage alloy is applied to prevent the natural boil-off gas from leaking to the outside and reuse the natural boil-off gas. According to the present invention, the system for storing liquefied hydrogen and collecting boil-off hydrogen comprises: a storage tank to store liquefied hydrogen; an insulation unit installed to enclose the outside of the storage tank to prevent external heat from being transferred into the storage tank; a hydrogen collection unit to absorb and store naturally boiled-off hydrogen gas discharged from the storage tank; a collection insulation unit enclosing the outside of the hydrogen collection unit; and a hydrogen discharge control unit to control the discharge of hydrogen gas from the storage tank to the hydrogen collection unit.

Description

System for storing liquefied hydrogen and collecting boil-off 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 and vaporization hydrogen capture system.

Hydrogen consists of only water as a fuel product, so it is possible to avoid concerns about environmental pollution such as sulfur oxides (SOx), nitrogen oxides (NOx), and carbon dioxide (CO2) 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 that requires advanced technology. For this reason, procurement from each country through hydrogen energy carriers is indispensable, and hydrogen carriers are known to be the best solution to the current problem. 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 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 insulation system and the mechanical performance to withstand the load caused by the movement of the ship during operation to prevent the generation of boil off gas (BOG) that occurs when it comes into contact with the temperature of outside air and sea water. 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 lead to 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 discharging the entire amount of boil off gas (BOG) generated in the tank to the outside, reusing it as propulsion fuel, and re-liquefying it.

However, if all BOG is discharged into the atmosphere, there is an economic loss due to the waste of hydrogen gas.If the natural gaseous gas is to be reused as propulsion fuel, additional piping is installed and 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)

It is an object of the present invention to prevent hydrogen embrittlement by making an 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 to obtain a hydrogen storage alloy. It relates to a liquefied hydrogen storage and vaporized hydrogen collection system that can be reused and prevented from outflow of natural vaporized gas by collecting and storing in a separate hydrogen collection unit to which is applied.

Liquefied hydrogen storage and vaporization hydrogen collection system according to the present invention for achieving the above object, a storage tank for storing liquefied hydrogen; A heat insulation part installed to surround the outside of the storage tank to prevent external heat from being transferred into the storage tank; A hydrogen collecting unit for absorbing and storing the naturally vaporized hydrogen gas discharged from the storage tank; A collection and insulation unit surrounding the outside of the hydrogen collection unit; And a hydrogen discharge control unit for controlling discharge of hydrogen gas from the storage tank to the hydrogen collection unit.

The hydrogen collection unit is installed inside the collection and insulation unit, a hydrogen collection unit made of a hydrogen storage alloy that absorbs and expands hydrogen gas discharged through the hydrogen discharge control unit, and supports the hydrogen collection unit inside the collection and insulation unit. It may include a support unit.

The support unit includes a support housing installed to surround the hydrogen collection unit in the collection insulation unit, and is disposed between the support housing and the hydrogen collection unit to support the hydrogen collection unit so as to expand and contract. It includes a deformation allowable member.

The deformation-allowing member may have a shape in which a plurality of hollow portions for elastic deformation are continuously arranged, and a plurality of grooves for allowing expansion of the hydrogen collecting unit are formed on the surfaces of the plurality of deformation-allowing members.

The deformation permitting member may be configured such that a circular or polygonal tube-shaped member having a hollow portion formed thereon is continuously arranged in a row between the support housing and the hydrogen collecting unit.

The hydrogen collection unit includes a collection frame in the form of a housing made of a hydrogen storage alloy that is installed inside the support unit and expands by absorbing hydrogen, and a plurality of collection frames made of a hydrogen storage alloy and arranged at intervals within the collection frame. It may include a collection bar.

It is preferable that the collection bars are arranged in a horizontal direction and a vertical direction on the collection frame.

In addition, the surfaces of the collection frame and the collection bar may be subjected to sand blasting.

The storage tank may include an inner wall made of a hydrogen storage alloy in which a chamber for storing the liquefied hydrogen is formed, and an outer wall made of a hard metal material that is installed to surround an outer surface of the inner wall to support the inner wall.

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

According to the present invention, in the process of storing and transporting liquefied hydrogen in a storage tank, when liquefied hydrogen is spontaneously evaporated to generate hydrogen gas, the hydrogen gas is discharged to a hydrogen collection unit configured outside the storage tank, and a hydrogen collection unit made of a hydrogen storage alloy Since it is absorbed and collected by the hydrogen gas, 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.

1 is a cross-sectional view of a liquid hydrogen storage and vaporization hydrogen collection system according to an embodiment of the present invention as viewed from the front.
2 is a cross-sectional view of the liquid hydrogen storage and vaporization hydrogen capture system shown in FIG. 1 from the side.
3 is a perspective view of portion A of FIG. 1.
FIG. 4 is an enlarged and cut-away view of a part of the portion shown in FIG. 3.
FIG. 5 is a diagram showing an example of operation of the portion shown in FIG. 3 when hydrogen is absorbed and discharged.

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 system for storing liquid hydrogen and collecting vaporized hydrogen will be described in detail with reference to the accompanying drawings according to embodiments described below. In the drawings, the same reference numerals denote the same components.

1 to 5, the liquefied hydrogen storage and vaporization hydrogen collection system according to an embodiment of the present invention includes a storage tank 10 for storing liquefied hydrogen (LH ₂ ), and an outer side of the storage tank 10 A heat insulation unit 20 installed so as to surround it to prevent external heat from being transferred into the storage tank 10, and a hydrogen collecting unit 30 that absorbs and stores naturally vaporized hydrogen gas discharged from the storage tank 10 , A collecting and insulating part 25 surrounding the outside of the hydrogen collecting part 30, and a hydrogen discharge control part controlling the discharge of hydrogen gas from the storage tank 10 to the hydrogen collecting part 30.

The storage tank 10 constitutes a container for storing cryogenic liquefied hydrogen (LH ₂ ) below -253°C, and an inner wall 11 made of a hydrogen storage alloy in which a chamber for storing the liquefied hydrogen is formed and , And an outer wall 12 made of a hard metal material that is installed to surround the outer surface of the inner wall 11 and supports the inner wall 11. The outer wall 12 may be made of SUS 304L, stainless steel, aluminum, etc., which are metals having excellent cryogenic resistance.

The inner wall 11 is made of a hydrogen storage alloy capable of absorbing and storing hydrogen. 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 that 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.

The heat insulating part 20 is configured to completely surround the outside of the storage tank 10 and serves to suppress the liquefied hydrogen in the storage tank 10 from being affected by external temperature. The heat insulating unit 20 may be configured by applying a heat insulating material configured in a cryogenic liquefied gas storage system such as known liquefied hydrogen or liquefied nitrogen.

The storage tank 10 is surrounded by the heat insulating part 20 so that external heat cannot be easily transferred into the storage tank 10, but heat cannot be completely blocked. Therefore, the natural vaporization of liquefied hydrogen (LH ₂ ) in the storage tank 10 cannot be completely eliminated, and although a very small amount, some degree of natural vaporization is inevitable.

The naturally vaporized hydrogen gas generated in the storage tank 10 is absorbed by the inner wall 11 made of a hydrogen storage alloy, but the hydrogen gas exceeding the hydrogen storage capacity of the inner wall 11 is a hydrogen capture unit ( 30) and collected.

The hydrogen discharge control unit connects the upper portion of the storage tank 10 and the hydrogen collecting unit 30 to guide the hydrogen gas of the storage tank 10 to the hydrogen collecting unit 30, and a hydrogen gas discharge pipe 41, It includes 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 hydrogen gas discharge pipe 41 and the control valve 42 are made of a material having excellent cryogenic resistance.

The hydrogen collecting part 30 is disposed above the heat insulating part 20 and is configured to be sealed within the collecting heat insulating part 25. The collection heat insulating unit 25 may be configured by applying an insulating material that is the same as or similar to the heat insulating unit 20.

The hydrogen collection unit 30 includes a hydrogen collection unit made of a hydrogen storage alloy installed inside the collection and insulation unit 25 to absorb and expand hydrogen gas discharged through the hydrogen discharge control unit, and the hydrogen collection unit. It includes a support unit supporting the inside of the collecting heat insulating part (25).

The hydrogen collecting unit is configured to collect as much labor gas as possible within a small installation space. To this end, in this embodiment, the hydrogen collection unit is installed inside the support housing 35 constituting the support unit, and a collection frame 31 in the form of a case made of a hydrogen storage alloy that absorbs and expands hydrogen, and a hydrogen storage alloy And a plurality of collection bars 32 arranged at intervals from each other in the collection frame 31.

The collection frame 31 has a rectangular parallelepiped shape and is installed inside the support housing 35 at regular intervals. The lower surface of the collection frame 31 is connected to a hydrogen gas discharge pipe 41 passing through the lower portion of the support unit to receive hydrogen gas.

The collection bars 32 intersect while being arranged in a horizontal direction and a vertical direction in the inner space of the collection frame 31, but are installed at regular intervals without contacting each other in consideration of the amount of expansion due to hydrogen absorption. The collection bar 32 may be formed of a circular bar or a polygonal bar having a predetermined diameter. In addition, in order to increase the surface area to improve the hydrogen storage capacity, the surfaces of the collection frame 31 and the collection bar 32 may be subjected to sand blasting.

The support unit supports the collection frame 31 of the hydrogen collection unit so that expansion and contraction are possible, and a support housing 35 installed to surround the collection frame 31 inside the collection insulation unit 25 ), and a deformation permitting member 36 disposed between the support housing 35 and the collecting frame 31 to support the collecting frame 31 so as to expand and contract.

The support housing 35 is in the form of a rectangular parallelepiped housing and is accommodated inside the collecting insulation unit 25, and can be made of a steel material having high strength and cryogenic resistance capable of withstanding the expansion and deformation of the hydrogen collecting unit. .

The deformation permitting member 36 is in the form of a hollow tube and a plurality of the support housing 35 and the collecting frame 31 are continuously arranged. The deformation permitting member 36 has a honeycomb shape in which a plurality of hollow parts 37 for elastic deformation are successively arranged, and the surface of the plurality of deformation permitting members 36 prevents the expansion of the hydrogen collecting unit. It has a structure in which a plurality of grooves 38 are formed to allow. The deformation-allowing member 36 may be made integrally, but differently, a circular or polygonal (preferably hexagonal) tube-shaped member in which the hollow part 37 is formed is the support housing 35 and the collecting frame 31 ) Can be made by successively arranged in a line along the horizontal or vertical direction.

The groove 38 of the deformation permitting member 36 is preferably formed at a position corresponding to the collecting bar 32.

When the deformation permitting member 36 in the form of a honeycomb is formed between the support housing 35 and the collecting frame 31 in this way, the collecting frame 31 and the collecting bar 32 are formed as shown in FIG. When hydrogen is absorbed and expanded, the portion that is expanded and deformed enters the inside of the groove 38 of the deformation-allowing member 36, so that the expansion is smoothly performed and hydrogen absorption may be smoothly performed. In addition, deformation of the collecting frame 31 and the collecting bar 32 exceeding the size of the groove 38 may be sustained while elastically deforming the deformation-allowing member 36.

The liquid hydrogen storage and vaporization hydrogen capture system with this configuration operates as follows.

In the process of storing and transporting liquefied hydrogen (LH ₂ ) in the storage tank 10, the hydrogen gas vaporized in the storage tank 10 is primarily absorbed by the inner wall 11 made of a hydrogen storage alloy. When the amount of hydrogen gas not absorbed by the inner wall 11 of the storage tank 10 increases and the pressure inside the storage tank 10 rises above a certain pressure value, the control valve 42 is opened and the storage tank (10) The internal hydrogen gas is discharged into the space inside the collection frame 31 of the hydrogen collection unit 30 through the hydrogen gas discharge pipe 41.

The hydrogen gas discharged to the inner space of the collection frame 31 is absorbed and collected by a plurality of collection bars 32 and collection frames 31 made of a hydrogen storage alloy. At this time, the collection bar 32 and the collection frame 31 gradually expand as they absorb hydrogen, and expansion and deformation are naturally induced by the groove 38 formed in the deformation-allowing member 36 of the support unit. Can be smoothly absorbed.

In addition, since the plurality of collection bars 32 arranged in the collection frame 31 are installed to be spaced apart from each other by a predetermined distance, even if the collection bars 32 expand, they can be expanded and deformed smoothly without contacting each other.

As described above, 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 a hydrogen collection unit configured outside the storage tank 10 ( 30), and is absorbed by the hydrogen collection unit made of a hydrogen storage alloy, that is, the collection frame 31 and the collection bar 32, so that hydrogen gas can be safely discharged without configuring a separate safety device for external discharge of hydrogen gas. Can remain, and the pressure inside the storage tank 10 can be kept constant.

The hydrogen gas collected in the hydrogen collection unit 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 below.

LH ₂ : Liquid hydrogen 10: Storage tank
20: heat insulation part 25: collection heat insulation part
30: hydrogen collection unit 31: collection frame
32: collection bar 35: support housing
36: deformation allowable member 37: hollow part
38: groove 41: hydrogen gas discharge pipe
42: control valve

Claims (10)

A storage tank for storing liquid hydrogen;
A heat insulation part installed to surround the outside of the storage tank to prevent external heat from being transferred into the storage tank;
A hydrogen collecting unit for absorbing and storing the naturally vaporized hydrogen gas discharged from the storage tank;
A collection and insulation unit surrounding the outside of the hydrogen collection unit;
And,
A hydrogen discharge control unit for controlling discharge of hydrogen gas from the storage tank to the hydrogen collection unit;
Liquefied hydrogen storage and vaporization hydrogen capture system comprising a. The method of claim 1, wherein the hydrogen collecting unit comprises a hydrogen collecting unit made of a hydrogen storage alloy installed inside the collecting and insulating unit to absorb and expand hydrogen gas discharged through the hydrogen discharge control unit, and the hydrogen collecting unit. Liquefied hydrogen storage and vaporization hydrogen collection system including a support unit supported inside the collective heat unit. The method of claim 2, wherein the support unit includes a support housing installed to surround the hydrogen collection unit inside the collection insulation unit, and is disposed between the support housing and the hydrogen collection unit to expand and contract the hydrogen collection unit. Liquefied hydrogen storage and vaporization hydrogen collection system including a deformation-allowing member that supports deformation. The method of claim 3, wherein the deformation-allowing member has a shape in which a plurality of hollow portions for elastic deformation are continuously arranged, and a plurality of grooves for allowing expansion of the hydrogen collecting unit are formed on the surfaces of the plurality of deformation-allowing members. Liquid hydrogen storage and vaporization hydrogen capture system. The liquefied hydrogen storage and vaporization hydrogen collection system according to claim 4, wherein the deformation-allowing member comprises a circular or polygonal tube-shaped member having a hollow portion formed in a row between the support housing and the hydrogen collecting unit. The method according to any one of claims 2 to 5, wherein the hydrogen collection unit comprises a collection frame in the form of a housing made of a hydrogen storage alloy that is installed inside the support unit and expands by absorbing hydrogen, and a hydrogen storage alloy. Liquefied hydrogen storage and vaporization hydrogen collection system including a plurality of collection bars arranged at intervals from each other in the collection frame. The system of claim 6, wherein the collection bars are arranged in a horizontal direction and a vertical direction in a collection frame. The system of claim 6, wherein the surfaces of the collection frame and the collection bar are sand blasted to store liquid hydrogen and collect vaporized hydrogen. The method of claim 1, wherein the storage tank comprises an inner wall made of a hydrogen storage alloy in which a chamber for storing the liquefied hydrogen is formed, and an outer wall made of a hard metal material that is installed to surround the outer surface of the inner wall to support the inner wall. Liquefied hydrogen storage and vaporization hydrogen capture system including. 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 hydrogen collecting unit to guide hydrogen gas from the storage tank to the hydrogen collecting unit, and opening or closing according to the pressure inside the storage tank Liquefied hydrogen storage and vaporization hydrogen collection system including a control valve that controls the discharge of hydrogen gas through the hydrogen gas discharge pipe while being closed.

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