JP3456044B2 - Cryogenic liquefied gas storage tank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cryogenic liquefied gas storage tank.

[0002]

2. Description of the Related Art Recently, clean hydrogen fuel has attracted attention as compared with fossil fuel such as liquefied natural gas, and it is expected that fossil fuel will be replaced with hydrogen fuel in the future.

When the era of hydrogen fuel comes into full swing, a hydrogen base equipped with a large number of large liquid hydrogen storage tanks having a scale of tens to hundreds of thousands of cubic meters is required.

By the way, the boiling point of liquid hydrogen is −253 ° C.
A large-scale liquid hydrogen storage tank, which is a cryogenic liquefied gas of the present invention and has a scale of tens of thousands to hundreds of thousands of cubic meters capable of storing such cryogenic liquid hydrogen, does not exist at present.

On the other hand, the liquefied natural gas currently used as a fuel is a low temperature liquefied gas having a boiling point of -162 ° C. A liquefied natural gas storage tank for storing such liquefied natural gas is shown in FIG. It has such a structure.

That is, the outer side of the inner tank 2 made of a thin metal membrane capable of storing the liquefied natural gas 1 is provided with a heat insulating space,
It has a large thickness and is surrounded by a rigid outer tub 3 such as made of concrete having a very high pressure resistance, and the inner tub 2 can be supported in a heat insulating space between the inner tub 2 and the outer tub 3. It has a structure in which a heat insulating layer 4 such as polyurethane having high pressure resistance is filled.

In the heat insulating space between the inner tank 2 and the outer tank 3,
Usually, air or helium gas of about 1 atm is enclosed.

In the figure, 5 is the roof of the outer tank 3 and 6 is the inner tank 2.
It is a support made of heat insulating material that supports the bottom of the.

In the liquefied natural gas storage tank, the liquefied natural gas 1 is stored in the inner tank 2 made of a thin metal membrane.

The inside and outside are insulated by the heat insulating layer 4.

Furthermore, the load of the liquefied natural gas 1 and the inner tank 2 made of a thin metal membrane is supported by the outer tank 3 made of concrete or the like having a very high compressive strength through the heat insulating layer 4. I am letting you.

[0012]

However, when the above conventional liquefied natural gas storage tank is used as it is for the storage of liquid hydrogen, the following problems occur.

That is, the loads of the liquefied natural gas 1 and the inner tank 2 are supported through the heat insulating layer 4 by the outer tank 3 having a rigid structure made of concrete and having a very high pressure resistance. Therefore, the heat insulating layer 4 is also required to have a high pressure resistance strength capable of supporting the loads of the liquefied natural gas 1 and the inner tank 2. Therefore, it is unavoidable to use polyurethane having a high density for the heat insulating layer 4.

However, since polyurethane having a high density has poor heat insulating performance, the desired heat insulating performance cannot be exhibited unless the thickness dimension is increased accordingly. However, since liquid hydrogen has a lower boiling point than liquefied natural gas 1, loss due to evaporation is likely to occur. Therefore, in order to store such liquid hydrogen, the heat insulating layer 4 must be made considerably thicker than in the case of the liquefied natural gas 1.

Specifically, since liquid hydrogen evaporates about 10 times more easily than liquefied natural gas 1, in order to store the same volume of liquid hydrogen, the thickness of the liquid hydrogen is 10 times or more that of liquefied natural gas 1. The heat insulation layer 4 is required, and if the inner tank 2 has a diameter of 4
Assuming that there is a liquefied natural gas storage tank having a thickness of 0 m, a thickness of the heat insulating layer 4 of 1 m, and a diameter of the outer tank 3 of 42 m, to store the same volume of liquid hydrogen, the diameter of the inner tank 2 is 40 m, and the heat insulating layer 4 is The thickness of the tank must be 10 m and the diameter of the outer tank 3 must be 60 m, and the entire tank becomes very large.

As described above, when the tank becomes large, the strength of the outer tub 3 and the heat insulating layer 4 must be increased accordingly, and it becomes difficult to adopt the rigid outer tub 3 this time.

Therefore, the structure of the liquefied natural gas storage tank cannot be applied to the liquid hydrogen storage tank.

In view of the above situation, the present invention has a cryogenic liquefied gas storage that enhances the heat insulation performance and adopts a flexible structure on the outside to miniaturize the whole so that liquid hydrogen can also be stored. It is intended to provide a tank.

[0019]

DISCLOSURE OF THE INVENTION The present invention has a thin metal inner tank capable of storing a cryogenic liquid therein and having a strength required to maintain a liquid pressure, and a vacuum is formed outside the inner tank. A membrane vacuum chamber made of a thin metal, which has a space and is surrounded, and which is formed of a corrugated and is expandable and contractable, and
A foamable heat insulating layer disposed in the vacuum forming space and having a strength sufficient to hold a membrane vacuum tank, a reinforcing rib provided at the bottom of the inner tank to prevent the bottom from expanding, and a membrane vacuum The present invention relates to a cryogenic liquefied gas storage tank, which is provided with a heat insulating material support made of a heat insulating material so as to be able to support the bottom of the inner tank.

In this case, the outer side of the membrane vacuum chamber may be surrounded by an outer shell.

[0021]

The operation of the present invention is as follows.

Storage of a cryogenic liquid such as liquid hydrogen is performed by a thin metal inner tank.

Since the inner tank has a thickness dimension or strength that is necessary for maintaining the liquid pressure, it can hold the liquid hydrogen without any trouble.

At this time, since the reinforcing ribs are provided at the bottom of the inner tank, the bottom of the inner tank is prevented from bulging, so that the thickness of the bottom of the inner tank at which the pressure of the cryogenic liquid becomes particularly large is increased. Can be eliminated to increase the strength.

In addition, since the reinforcing rib is provided, it is possible to prevent the bottom portion of the inner tank from swelling. Therefore, the expanded diameter of the bottom portion of the inner tank causes the foamed heat insulating layer to be displaced, which causes It is prevented that the heat insulation performance is deteriorated.

Since the membrane vacuum chamber has a flexible structure made of metal such as thin stainless steel, the membrane vacuum chamber is supported by the inner chamber via the foaming heat insulating layer.

Then, in the inner tank, the load of the cryogenic liquid acting from the inside is balanced with the load of the foaming heat insulating layer and the membrane vacuum tank working from the outside, and the inner tank balances the load of the foaming heat insulating layer and the membrane vacuum. It is possible to hold the tank without any trouble.

The foaming heat insulating layer need only have a strength that can support the load of the thin and light membrane vacuum chamber, so that the density can be made extremely small, whereby the heat insulating performance can be greatly improved. Can be improved.

The pressure in the space inside the inner tank is suppressed to about 1 atm because the heat insulation performance is improved and evaporation of the cryogenic liquid is suppressed, and the pressure outside the membrane vacuum tank is set to about atmospheric pressure. Therefore, the pressure inside and outside the inner tank is also balanced.

As described above, since the membrane vacuum chamber corresponding to the outer chamber has the flexible structure, the entire size can be greatly reduced.

Since the cryogenic liquid has a very low boiling point, even if a small amount of heat is invaded from the outside, it will evaporate and cause a loss. It is possible to use a foaming heat insulating layer having a very small heat insulating property and having a good heat insulating performance, so that evaporation can be effectively prevented.

Further, since the cryogenic liquid has a temperature lower than the condensation temperature of almost all gases (approximately 40 K), the inside of the vacuum forming space between the inner tank and the membrane vacuum tank is 10 ^-2 To during manufacturing.
When the low-temperature liquid is stored, the gas in the vacuum forming space is condensed and the vacuum in the vacuum forming space becomes a vacuum, so that the convective heat transfer due to the convection of the gas becomes 0 by simply roughing the vacuum to about rr. A vacuum insulation state is formed.

If the conventional storage tank (FIG. 5) is used for liquid hydrogen, the adiabatic space becomes a vacuum and the inner tank and the outer tank need to be structurally independent of each other. The internal pressure tank of atmospheric pressure and the external tank become the external pressure tank of 1 atmospheric pressure.

Since the above-mentioned vacuum heat insulation has a higher heat insulation effect than the normal pressure heat insulation, when combined with the heat insulation effect of the foaming heat insulation layer having a small density and a small solid heat transfer, a very high heat insulation performance can be obtained. A high heat insulating effect can be secured even as a thin heat insulating layer.

Although the foaming heat insulating layer contracts due to the cold heat of the cryogenic liquid, the membrane vacuum tank is formed so that waves (corrugates) such as vertical and horizontal directions are formed on the surface thereof and can expand and contract in the plane direction. The membrane vacuum chamber can be deformed following the shrinkage of the foam heat insulating layer.

Since the membrane vacuum chamber is thin, it is likely to be damaged by an external impact or the like, so an outer shell may be provided to protect it.

The bottom of the inner tank is supported by the foundation via a heat insulating material support.

[0038]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of the present invention.

A thin metal inner tank 8 capable of storing a cryogenic liquid 7 such as liquid hydrogen is provided inside, which has a thickness dimension or strength required for maintaining a liquid pressure.

The inner tank 8 is made of, for example, aluminum alloy or stainless steel.

The outer side of the inner tank 8 is enclosed in a thin metal membrane vacuum tank 9 having a vacuum forming space 9a so as to be hermetically sealed.

The membrane vacuum chamber 9 is made of stainless steel or the like, and has longitudinal and horizontal (or diagonal) waves (corrugations 10) as shown in FIG.

In the vacuum forming space 9a, a foaming heat insulating layer 11 made of polyurethane foam having a strength sufficient to hold the membrane vacuum tank 9 is arranged.

The expandable heat insulating layer 11 is formed by stacking expanded polyurethane foam blocks 12 as shown in FIG.

Further, foamed polyurethane foam block 1
No. 2 has a very low density of about 32 kg / m ³ and is in a scathed state having a large number of small spaces 14 partitioned by an extremely thin film 13 inside.

The inside of the vacuum forming space 9a is lightly evacuated to about 10 ^-2 Torr during manufacturing.

Further, a reinforcing rib 15 is provided at the bottom of the inner tank 8 to prevent the bottom of the inner tank 8 from bulging.

For example, as shown in FIG. 4, the reinforcing ribs 15 are formed by welding one ends of a plurality of perforated frame-shaped plates 16 to each other at the axial center position of the inner tank 8 to form a radius of the inner tank 8. The other end extending in the direction is welded to the inner peripheral surface of the inner tank 8.

Furthermore, inside the membrane vacuum tank 9, the inner tank 8 is
An insulating material support 17 capable of supporting the bottom of the is provided.

For the heat insulating material support 17, it is preferable to use a wood type heat insulating material such as balsa or plywood.

Further, the outer side of the membrane vacuum chamber 9 is surrounded by the outer shell 18.

The outer shell 18 is a cover provided only for the purpose of protecting the thin membrane vacuum tank 9, and the space 19 between the outer shell 18 and the membrane vacuum tank 9 is, for example, a space so as to be almost equal to the atmospheric pressure. 19 may be opened to the atmosphere or filled with nitrogen gas or air of about 1 atm.

Reference numeral 20 is a port for the cryogenic liquid 7.

Next, the operation will be described.

Storage of the cryogenic liquid 7 such as liquid hydrogen is carried out by a thin metal inner tank 8.

Since the inner tank 8 has a thickness dimension or strength that is necessary for maintaining the liquid pressure, it can hold the liquid hydrogen without any trouble.

At this time, the reinforcing ribs 15 are provided on the bottom of the inner tank 8.
Since the bottom of the inner tank 8 is prevented from swelling by providing the inner tank 8, the inner tank 8 in which the pressure of the cryogenic liquid 7 becomes particularly large
It is possible to eliminate the need to increase the thickness by increasing the thickness of the bottom portion.

In addition, since the reinforcing ribs 15 are provided, it is possible to prevent the bottom of the inner tank 8 from swelling, and the expanded diameter of the bottom of the inner tank 8 causes the foamed polyurethane foam block 12 to be displaced. It is possible to prevent the heat insulating performance of the part from being deteriorated.

Since the membrane vacuum chamber 9 corresponding to the outer chamber 3 in FIG. 5 has a flexible structure made of a metal such as thin stainless steel, the membrane vacuum chamber 9 has the foamable heat insulating layer 1
1 will be supported by the inner tank 8.

Then, in the inner tank 8, the load of the cryogenic liquid 7 acting from the inside and the foaming heat insulating layer 11 acting from the outside
And the load of the membrane vacuum tank 9 is balanced, and the foamable heat insulating layer 11 and the membrane vacuum tank 9 can be held by the inner tank 8 without any trouble.

Since the foamable heat insulating layer 11 only needs to have a strength that can support the load of the thin and light membrane vacuum chamber 9, it has a very small density of about 32 kg / m ³ and has an extremely thin film inside. Small space 1 divided by 13
It becomes possible to use a foamed polyurethane foam having a large number of 4 in a squeezed state, which can greatly improve the heat insulating performance, as described later.

The pressure in the space inside the inner tank 8 is suppressed to about 1 atm because the heat insulation performance is improved and the evaporation of the cryogenic liquid 7 is suppressed, and the pressure outside the membrane vacuum tank 9 is also as described above. Since the pressure is set to about atmospheric pressure, the pressure inside and outside the inner tank 8 is also balanced.

As described above, by making the membrane vacuum tank 9 corresponding to the outer tank 3 of FIG. 5 a flexible structure, the structure of the liquefied natural gas storage tank having the rigid outer tank 3 of FIG. Compared with the case where it is used for the cryogenic liquid 7 such as hydrogen, it is possible to make the whole size significantly smaller.

Since the boiling point of liquid hydrogen as the cryogenic liquid 7 is as very low as −253 ° C., if a slight amount of heat is introduced from the outside, the liquid hydrogen will evaporate and cause a loss. However, in the present embodiment, as described above, the foamable heat insulating layer 11 having a very low density and made of a squashed polyurethane foam having a large number of small spaces 14 partitioned by the extremely thin film 13 inside has a good heat insulating performance.
Can be used, so that evaporation of liquid hydrogen can be effectively prevented.

Here, the heat insulation performance of the foamed polyurethane foam includes solid heat transfer transmitted through the material itself of the foamed polyurethane foam and the small space 1 inside the foamed polyurethane foam.
4 and the radiant heat transmitted through the film 13 constituting the small space 14 and the small space 14
It depends on the convective heat transfer that is transmitted by the convection of the foaming gas enclosed in the foamed polyurethane foam according to the present embodiment because the density is small, the solid heat transfer is small,
As compared with the heat insulating layer 4 such as polyurethane having a high density and a large solid heat transfer in FIG. 5, the heat insulating performance can be significantly improved.

Moreover, since the temperature of liquid hydrogen as the cryogenic liquid 7 is a cryogenic temperature of −253 ° C. or lower, which is lower than the condensation temperature of almost all gases (approximately 40K), the inner tank 8 and the membrane vacuum are manufactured. Vacuum forming space 9 with the tank 9
When liquid hydrogen is stored, the gas in the vacuum forming space 9a and the foaming gas in the small space 14 of the foamed polyurethane foam block 12 are condensed by simply evacuating the inside of a to a rough vacuum of about 10 ^-2 Torr. As a result, the inside of the vacuum forming space 9a and the inside of the small space 14 become a vacuum, and the convective heat transfer due to the convection of the gas becomes 0, so that the vacuum heat insulating state is formed.

In the case of the liquefied natural gas storage tank of FIG. 5, since the temperature is -162 ° C., which is higher than the condensation temperature of gas or air, such a vacuum adiabatic state cannot be obtained in the adiabatic space, and the atmospheric pressure cannot be obtained. It becomes heat insulation.

Further, if the conventional storage tank (FIG. 5) is used for liquid hydrogen, the heat insulating space becomes a vacuum, and it becomes necessary to provide the inner tank 2 and the outer tank 3 independently from each other. The tank is an internal pressure tank with a pressure of 1 atm, and the external tank is an external pressure tank with a pressure of 1 atm.

Since the vacuum heat insulation has a higher heat insulation effect than the normal pressure heat insulation, when combined with the heat insulation effect of the foaming heat insulation layer 11 of polyurethane foam having a low density and a small solid heat transfer, the case of FIG. A heat insulating performance as high as about 10 times or more can be obtained, and a high heat insulating effect can be secured even with the thin foamable heat insulating layer 11.

The cold heat of the cryogenic liquid 7 causes the foamable heat-insulating layer 11 made of polyurethane foam to shrink, but the membrane vacuum chamber 9 has a surface with corrugations (corrugates 10) formed vertically and horizontally. Since it can be expanded and contracted in the direction, it can be deformed following the contraction of the foamable heat insulating layer 11 made of polyurethane foam.

Since the membrane vacuum chamber 9 is thin, it is apt to be damaged by an external impact or the like, so that the outer shell 18 is provided to protect it.

The bottom of the inner tank 8 is supported by the foundation via a wood-based heat insulating material support 17.

The present invention is not limited to the above-mentioned embodiments, the cryogenic liquid is not limited to liquid hydrogen, the foamable heat insulating layer is not limited to polyurethane foam, and other Needless to say, various changes can be made without departing from the scope of the invention.

[0075]

As described above, according to the cryogenic liquefied gas storage tank of the present invention, the heat insulation performance is improved and
By adopting a flexible structure on the outer side and reducing the size of the whole, it is possible to achieve an excellent effect that the cryogenic liquid hydrogen can be stored without any trouble.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of an embodiment of the present invention.

FIG. 2 is a schematic view showing a state of a corrugate formed in a membrane vacuum chamber.

FIG. 3 is a schematic perspective view showing a foamed polyethylene foam.

FIG. 4 is a schematic perspective view showing a state of reinforcing ribs provided on the bottom of the inner tank.

FIG. 5 is a schematic side sectional view of a liquefied natural gas storage tank.

[Explanation of symbols]

7 Cryogenic liquid 8 inner tank 9 Membrane vacuum tank 9a Vacuum forming space 10 corrugated 11 Foaming insulation layer 15 Reinforcing rib 17 Insulation support 18 outer shell

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Riki Naito 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawa Shima Harima Heavy Industries Co., Ltd. Toyosu General Office (72) Inventor Takashi Yamaguchi Shin Isogo-ku, Yokohama-shi, Kanagawa 1 Nakahara-cho, Ishikawajima-Harima Heavy Industries Co., Ltd. Technical Research Institute (56) Reference JP-A-8-142976 (JP, A) JP-A-52-26010 (JP, A) JP-B-50-18270 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F17C 3/00-3/06 F17C 13/08 302 B65D 90/04 B63B 3/62 B63B 25/16

Claims (2)

(57) [Claims] 1. Having strength to the extent necessary to maintain hydraulic pressure,
A thin metal inner tank that can store cryogenic liquid inside, and a thin sealable container that surrounds the outer side of the inner tank with a vacuum forming space and is corrugated to allow expansion and contraction. The metal membrane vacuum tank, the foamable heat insulating layer arranged in the vacuum forming space and having a strength sufficient to hold the membrane vacuum tank, and the bottom provided in the bottom of the inner tank are prevented from swelling. A cryogenic liquefied gas storage tank, which is provided with a possible reinforcing rib and a heat insulating material support made of a heat insulating material so as to be able to support the bottom of the inner tank in the membrane vacuum tank. 2. The cryogenic liquefied gas storage tank according to claim 1, wherein the membrane vacuum tank is surrounded by an outer shell.