JP6909635B2 - Cryogenic gas storage tank - Google Patents

Description

The present invention relates to a flat-bottomed cylindrical low-temperature liquefied gas storage tank, and more particularly to a storage tank capable of storing liquefied hydrogen.

In the LNG tank, which is a cryogenic gas storage tank, a heat insulating material such as pearlite and glass wool is filled between the inner tank and the outer tank, and the heat insulating material is filled in order to prevent moisture from entering the pearlite. The space between the inner tank and the outer tank is filled with nitrogen gas as a dry gas, and the space between the inner and outer tanks is maintained in an inert atmosphere. In addition, by providing a breathing tank that connects to the nitrogen gas filling space between the inner and outer tanks, even if there are fluctuations in the outside temperature and pressure, the volume change of the nitrogen gas is adjusted and the filling pressure of the nitrogen gas is always about atmospheric pressure. Can be maintained at a constant pressure of.

The low-temperature tank described in Patent Document 1 has a concrete outer tank (liquid barrier) and a foundation slab, a liner plate attached to the inner surface of the outer tank and the foundation slab, and a heat insulating space inside the liner plate. It is provided with an inner tank made of concrete and a membrane made of steel for low temperature formed on the inner surface of the inner tank. A cooling pipe is buried in the concrete inner tank.
However, in this low temperature tank, a heat insulating layer is not formed between the inner tank and the membrane, and the heat insulating space between the inner and outer tanks is not filled with nitrogen gas.

JP-A-2002-267099

When liquefied hydrogen is stored in the inner tank in a storage tank in which the heat insulating space between the inner and outer tanks is filled with nitrogen gas like a conventional low-temperature liquefied gas storage tank, the boiling point (-253 ° C) of the hydrogen gas is nitrogen gas. Since it is lower than the boiling point (-196 ° C.) and the melting point (-210 ° C.) of the above, there is a problem that the nitrogen gas sealed between the inner and outer tanks is liquefied and solidified.

An object of the present invention is to provide a cryogenic liquefied gas storage tank capable of preventing liquefaction and solidification of the gas sealed between the inner and outer tanks.

The low-temperature liquefied gas storage tank according to claim 1 is a flat-bottomed cylindrical tank for storing low-temperature liquefied gas, and includes a steel inner tank, a steel outer tank formed on the outside of the inner tank, and the inner tank. A steel membrane formed inside, a first heat insulating space formed between the inner tank and the outer tank, and a second heat insulating space formed between the inner tank and the membrane. A cold insulation panel having a plurality of plate materials and a cold insulation material provided between the plate materials is provided, the first heat insulation space is filled with dry gas , and the cold insulation panel is arranged in the second heat insulation space. The cryogenic liquefied gas is liquefied hydrogen, and the dry gas is nitrogen gas .

According to the above configuration, since the second heat insulating space is provided between the inner tank and the membrane, there is a possibility that the dry gas filled in the first heat insulating space between the inner tank and the outer tank may be liquefied or solidified. do not have. For example, even if the cryogenic liquefied gas to be stored is liquefied hydrogen, nitrogen gas, which is an inert gas, can be adopted as the dry gas to be filled in the first heat insulating space.
Further, since a membrane is attached to the inner surface of the second heat insulating layer to seal off liquefied hydrogen, the choice of materials for the inner tank and the outer tank is expanded.
Moreover, even if liquefied hydrogen is stored in the membrane with the first heat insulating space filled with nitrogen gas, there is no possibility that the nitrogen gas will be liquefied or solidified because of the second heat insulating space.
In addition, the heat insulating property of the second heat insulating space can be improved.

Low-temperature liquefied gas storage tank according to claim 2 is the invention of claim 1, wherein the cold panels, a first plate abutting against the inner peripheral surface of the inner tub, and a second plate abutting against the outer circumferential surface of the membrane , The third plate material provided between the first plate material and the second plate material, the first cold insulation layer provided between the first plate material and the third plate material, the second plate material and the third plate material. It is characterized by being provided with a second cold insulation layer provided between the plate material.

According to the above configuration, the heat insulating property of the second heat insulating space can be improved by forming the cold insulation panel in a laminated structure.

Low-temperature liquefied gas storage tank according to claim 3 is the invention of claim 2, wherein the cold storage panel, the first anchor connecting the inner peripheral surface of the inner tub and the third plate member is fixed to the inner tub The membrane is characterized in that it is fixed to the cold insulation panel by a second anchor connecting the outer peripheral surface of the membrane and the third plate material.
According to the above configuration, since the heat bridge countermeasure is taken by connecting the inner tank and the membrane via the third plate material, the liquefied hydrogen stored in the membrane 7 is transferred from the outside (outside air). Heat input can be suppressed.

The low-temperature liquefied gas storage tank according to claim 4 is characterized in that, in the invention of any one of claims 1 to 3 , a breathing tank communicated with the first heat insulating space is provided.
According to the above configuration, the breathing tank can absorb the volume change of the inert gas in the heat insulating space due to the fluctuation of the outside air temperature and the atmospheric pressure and maintain the atmospheric pressure at substantially atmospheric pressure.

The low-temperature liquefied gas storage tank according to claim 5 is characterized in that, in the invention of any one of claims 1 to 4 , a cylindrical PC liquid barrier formed on the outside of the outer tank is provided.
According to the above configuration, even if the low temperature liquefied gas leaks from the inner tank and the outer tank due to some accident, the PC liquid barrier can prevent the leakage to the outside.

According to the present invention, various effects as described above can be obtained.

It is a vertical sectional view of the liquefied hydrogen storage tank which concerns on embodiment of this invention. It is an enlarged view of the part a of FIG. It is a membrane surface view seen from the inside of a membrane.

A mode for carrying out the present invention will be described with reference to the drawings.
The present embodiment is an example in which the low-temperature liquefied gas storage tank of the present invention is applied to a large-scale liquefied hydrogen storage tank.

As shown in FIG. 1, the liquefied hydrogen storage tank 1 is a flat-bottomed cylindrical tank that stores liquefied hydrogen (corresponding to a low-temperature liquefied gas). The liquefied hydrogen storage tank 1 has a first heat insulating space 4a (first heat insulating space 4a) having a first heat insulating layer 5 formed between the inner tank 2, the outer tank 3, the membrane 7, and the inner tank 2 and the outer tank 3. 1 heat insulating material arrangement room), a second heat insulating space 4b (second heat insulating material arrangement room) having a second heat insulating layer 6 formed between the inner tank 2 and the membrane 7, and the first heat insulating space 4a are filled. Nitrogen gas (corresponding to dry gas), a cylindrical PC liquid barrier 8 formed in contact with the outer peripheral surface of the outer tank 3, a breathing tank 9 provided outside the storage tank 1, and a breathing tank 9. It is provided with a connecting pipe 9a for connecting the breathing tank 9 to the first heat insulating space 4. "PC" is an abbreviation for prestressed concrete.

The inner tank 2 is made of low-temperature steel such as SUS304L or 9% Ni steel, and has a dome-shaped inner tank roof 2a, a cylindrical inner tank side plate 2b, and a disk-shaped inner tank bottom plate 2c. For example, the plate thickness of the inner tank roof 2a is about 5 mm, the plate thickness of the inner tank side plate 2b is about 10 to 20 mm, and the plate thickness of the inner tank bottom plate 2c is about 6 mm. It is not limited to the plate thickness of.

The outer tank 3 is made of ordinary steel such as SS41, and has a dome-shaped outer tank roof 3a, a cylindrical outer tank side plate 3b, and a disk-shaped outer tank bottom plate 3c. For example, the plate thickness of the outer tank 3 is about 3 to 4 mm, but this plate thickness is an example and is not limited to this plate thickness.

A first heat insulating layer 5 made of a heat insulating material is attached to the first heat insulating space 4a between the inner tank 2 and the outer tank 3.
The first heat insulating layer 5a between the inner tank roof 2a and the outer tank roof 3a is made of PUF (polyurethane foam) and granular pearlite. The first heat insulating layer 5b between the inner tank side plate 2b and the outer tank side plate 3b is made of, for example, PUF, granular pearlite, and glass wool. However, these heat insulating materials are examples, and the present invention is not limited thereto.

The first heat insulating layer 5c between the inner tank bottom plate 2c and the outer tank bottom plate 3c is composed of, for example, PUF, pearlite level concrete, foam glass, lightweight cellular concrete, and the like. However, these heat insulating materials are examples, and the present invention is not limited thereto.

A flat-bottomed cylindrical second heat insulating layer 6 attached to the entire inner surface of the inner tank 2 will be described with reference to FIG. The second heat insulating layer 6 is a cold insulation panel 6 in the present embodiment. The cold insulation panel 6 has a plurality of plate materials 10, 12, 14 and cold insulation layers (cold insulation materials) 11, 13 provided between these plate materials. Specifically, the cold insulation panel 6 includes a first plate material 10 that abuts on the inner peripheral surface of the inner tank 2, a second plate material 14 that abuts on the outer peripheral surface of the membrane 7, and the first plate material 10 and the second plate material 14. A third plate material 12 provided between the two plates, a first cold insulation layer 11 provided between the first plate material 10 and the third plate material 12, and a second plate material 12 provided between the second plate material 14 and the third plate material 12. It includes a cold insulation layer 13.

The first cold insulation layer 11 and the second cold insulation layer 13 are composed of a foamed heat insulating material such as PUF or phenol foam, and the first plate material 10, the first cold insulation layer 11, the third plate material 12, the second cold insulation layer 13 and the second The plate material 14 is joined by an adhesive, a fastening member, or the like to form a cold insulation panel. Further, the first plate material 10, the second plate material 14, and the third plate material 12 may be made of wood or resin, and the first cold insulation layer 11, the second cold insulation layer 13 may be a vacuum heat insulating material or a vacuum. It may be a heat insulating panel.
The cold insulation panel 6 is fixed to the inner surface of the inner tank 2 by a plurality of steel first anchors 15. The first anchor 15 has a bolt portion 15a, a head portion 15b integrated with the bolt portion 15a, and a nut 15c screwed into a screw portion at the tip portion of the bolt portion 15a.

The head portion 15b of the first anchor 15 is welded to the inner surface of the inner tank 2 and housed in the recess of the first plate material 10, and the bolt portion 15a connects the first plate material 10, the first cold insulation layer 11, and the third plate material 12. The cold insulation panel 6 is formed in the inner tank 2 by penetrating and projecting into the cavity portion 13a formed in the second cold insulation layer 13 and screwing the nut 15c into the bolt portion 15a from the inner surface side of the third plate member 12 in the cavity portion 13a. It is fixed to the inner surface of. After the nut 15c is fastened, the hollow portion 13a is backfilled with a cold insulating material 13b such as PUF.

As shown in FIGS. 2 and 3, the membrane 7 attached to the entire inner surface of the cold insulation panel 6 is made of austenitic stainless steel or other steel for low temperature and having hydrogen brittleness resistance, and the thickness thereof is 2. It is ~ 3 mm. However, the thickness is not limited to this.
In order to allow the membrane 7 to expand and contract in response to a change in the temperature inside the tank, the membrane 7 is formed with corrugations 7a bulging inward and extending in the vertical and horizontal directions in a mesh shape at predetermined intervals. There is.

The membrane 7 is fixed to the inner surface of the cold insulation panel 6 by a plurality of steel second anchors 16. The second anchor 16 has a bolt portion 16a, a head portion 16b integrated with the bolt portion 16a, and a nut member 16c screwed into a screw portion at the tip end portion of the bolt 16a. The head portion 16b is arranged in contact with the outer surface of the third plate material 12, and the bolt portion 16a penetrates the third plate material 12 and the second cold insulation layer 13 and extends to the second plate material 14.

The nut member 16c has a tubular portion screwed into the threaded portion at the tip of the bolt portion 16a and a circular portion integrally formed at the tip of the tubular portion. The nut member 16c is fitted into the stepped hole 14a formed in the second plate member 14, the tubular portion thereof is screwed into the threaded portion, and the circular portion is housed in the large diameter hole of the stepped hole 14a to form the circular portion. The tip surface is flush with the inner surface of the second plate member 14. By fastening the nut member 16c, the second cold insulation layer 13 and the second plate member 14 are connected to the third plate member 12.

A membrane 7 is attached to the inner surface of the cold insulation panel 6, and the membrane 7 is fixed to the inner surface of the cold insulation panel 6 by welding the membrane 7 to the tip surface of the circular portion of the nut member 16c of the second anchor 16 from the inside. ing.

In addition to the first heat insulating layer 5, dry gas is prevented from entering the first heat insulating space 4a together with air in the first heat insulating space 4a between the inner tank 2 and the outer tank 3. Is filled. In the present embodiment, the dry gas is filled with nitrogen gas, which is an inert gas, and the space between the inner and outer tanks is maintained in an inert atmosphere.
The breathing tank 9 is for absorbing the volume change of the nitrogen gas in the first heat insulating space 4a due to the fluctuation of the outside air temperature and the atmospheric pressure and keeping the pressure of the nitrogen gas at a substantially atmospheric pressure.
The breathing tank 9 is a general one having a steel tank main body and a diaphragm balloon with a counter weight that divides the inside of the tank main body into a nitrogen gas accommodating portion and an air opening chamber. The nitrogen gas accommodating portion is connected to the first heat insulating space 4a by a connecting pipe 9a.

Next, the action and effect of the liquefied hydrogen storage tank 1 described above will be described.
Since the second heat insulating layer 6 is formed on the inner surface of the inner tank 2 and the membrane 7 is attached to the inner surface of the second heat insulating layer 6, the first heat insulating space 4a between the inner tank 2 and the outer tank 3 is filled with nitrogen gas. Even so, there is no risk of liquefaction or solidification of nitrogen gas.

Moreover, since the first heat insulating space 4a filled with the nitrogen gas is connected to the breathing tank 9 via the connecting pipe 9a, the volume change of the nitrogen gas due to the fluctuation of the outside temperature and the atmospheric pressure is absorbed and the pressure becomes a constant pressure close to the atmospheric pressure. Can be retained.
Since the membrane 7 is attached to the inner surface of the second heat insulating layer 6 to seal off the liquefied hydrogen, the choice of materials for the inner tank 2 and the outer tank 3 is expanded.

Since the breathing tank 9 communicated with the first heat insulating space 4a is provided, the breathing tank 9 absorbs the volume change of the nitrogen gas in the first heat insulating space 4a due to the fluctuation of the outside air temperature and the atmospheric pressure, and the atmospheric pressure is substantially atmospheric pressure. Can be held in.

Since the cylindrical PC liquid barrier 8 formed on the outside of the outer tank 3 is provided, even if the low temperature liquefied gas leaks from the inner tank 2 and the outer tank 3 due to some accident, the PC liquid barrier 8 provides the outside. It is possible to prevent leakage to.

In order to provide the cold insulation panel 6 on the inner surface side of the inner tank 2 and attach the membrane 7 to the inner surface of the cold insulation panel 6, liquefied hydrogen is stored in the membrane 7 in a state where the first heat insulating space 4a is filled with nitrogen gas. However, there is no risk that the nitrogen gas will liquefy or solidify.

The cold insulation panel 6 is fixed to the inner tank 2 by a first anchor 15 that connects the third plate material 12 and the inner peripheral surface of the inner tank 2, and the membrane 7 is connected to the outer peripheral surface of the membrane 7 and the third plate material 12. Is fixed to the cold insulation panel 6 by the second anchor 16 connecting the two anchors. That is, the first and second anchors 15 and 16 made of steel fix the cold insulation panel 6 to the inner tank 2 and the membrane 7 to the cold insulation panel 6, but between the inner tank 2 and the membrane 7. It is connected via a third plate made of wood or resin with low thermal conductivity (that is, measures against heat bridge are taken). Therefore, it is possible to suppress heat input from the outside (outside air) to the liquefied hydrogen stored in the membrane 7, and it is possible to secure the heat insulating property of the liquefied hydrogen storage tank 1 as a whole.

Next, an example of partially modifying the above embodiment will be described.
1) The low-temperature liquefied gas storage tank 1 can be similarly applied to a low-temperature liquefied gas storage tank that stores liquefied helium.
2) Instead of the PC liquid barrier 8, a steel cylindrical liquid barrier may be provided.

3) The liquefied hydrogen storage tank 1 has been described by taking an above-ground storage tank as an example, but it may be configured as an underground storage tank or a semi-underground storage tank.
4) In addition, a person skilled in the art can carry out the embodiment in a form in which various modifications are added to the above embodiment without deviating from the gist of the present invention, and the present invention includes these modified forms.

1 Liquefied hydrogen storage tank 2 Inner tank 3 Outer tank 4a 1st heat insulation space 4b 2nd heat insulation space
5 1st heat insulating layer 6 2nd heat insulating layer (cold insulation panel)
7 Membrane 8 PC liquid barrier 9 Breathing tank 10 1st plate 11 1st cold insulation layer 12 3rd plate 13 2nd cold insulation layer 14 2nd plate 15 1st anchor 16 2nd anchor

Claims (5)

In a flat-bottomed cylindrical tank that stores cryogenic liquefied gas
Steel inner tank and
A steel outer tank formed on the outside of the inner tank and
A steel membrane formed inside the inner tank and
A first heat insulating space formed between the inner tank and the outer tank,
A second heat insulating space formed between the inner tank and the membrane,
A cold insulation panel having a plurality of plate materials and a cold insulation material provided between these plate materials is provided.
The first heat insulating space is filled with dry gas ,
The cold insulation panel is arranged in the second heat insulating space, and the cold insulation panel is arranged.
A cryogenic gas storage tank characterized in that the cryogenic liquefied gas is liquefied hydrogen and the dry gas is nitrogen gas. A third plate material in which the cold insulation panel abuts on the inner peripheral surface of the inner tank, a second plate material abutting on the outer peripheral surface of the membrane, and a third plate material provided between the first plate material and the second plate material. It is provided with a plate material, a first cold insulation layer provided between the first plate material and the third plate material, and a second cold insulation layer provided between the second plate material and the third plate material. The low temperature liquefied gas storage tank according to claim 1. The cold insulation panel is fixed to the inner tank by a first anchor connecting the third plate material and the inner peripheral surface of the inner tank.
The low-temperature liquefied gas storage tank according to claim 2 , wherein the membrane is fixed to the cold insulation panel by a second anchor connecting the outer peripheral surface of the membrane and the third plate material. The low-temperature liquefied gas storage tank according to any one of claims 1 to 3, wherein a breathing tank is provided in communication with the first heat insulating space. The low-temperature liquefied gas storage tank according to any one of claims 1 to 4, further comprising a cylindrical PC liquid barrier formed on the outside of the outer tank.

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