JP7633680B2

JP7633680B2 - Multi-hull cryogenic tank

Info

Publication number: JP7633680B2
Application number: JP2022009433A
Authority: JP
Inventors: 宏治石井; 昭塚原
Original assignee: 株式会社石井鐵工所
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2025-02-20
Anticipated expiration: 2042-01-25
Also published as: JP2023108356A

Description

この発明は、多重殻の低温タンクに関する。 This invention relates to a multi-shell cryogenic tank.

内殻と外殻との間に真空断熱層を設けた二重殻低温タンクは、タンク外部の大気圧と内殻と外殻の間の高真空の真空断熱層との圧力差に耐え得るように内殻、外殻の板厚を設計する必要がある。 Double-shell cryogenic tanks with a vacuum insulation layer between the inner and outer shells must have the thickness of the inner and outer shells designed to withstand the pressure difference between the atmospheric pressure outside the tank and the high vacuum insulation layer between the inner and outer shells.

また、内殻と外殻の間に真空断熱層を設けた二重殻低温タンクの製作には、内殻と外殻の間を所定の高真空に達するまで減圧排気する作業に時間と手間を必要とする。特に、二重殻低温タンクの大型化においては内殻と外殻の間の真空断熱層の容積が増大するため、その減圧排気に要する時間や手間が大幅に増加する。 In addition, the production of a double-shelled cryogenic tank with a vacuum insulation layer between the inner and outer shells requires time and effort to evacuate the space between the inner and outer shells until a specified high vacuum is reached. In particular, when making larger double-shelled cryogenic tanks, the volume of the vacuum insulation layer between the inner and outer shells increases, so the time and effort required to evacuate the space increases significantly.

これまで、二重殻を含む多重殻タンクの従来技術（特許文献１～３）が開示されている。 To date, conventional technologies for multi-shell tanks, including double-shell tanks, have been disclosed (Patent Documents 1 to 3).

特許文献１には、複数の貯蔵室が区画形成され、多種類の圧力の流体を貯蔵できる多重殻高圧タンクが開示されている。 Patent document 1 discloses a multi-shelled high-pressure tank that has multiple storage chambers and can store fluids at various pressures.

特許文献２には、真空断熱層を第１と第２の真空断熱層の二重にし、液体水素等の極低温の液体を貯蔵し、真空断熱層のそれぞれの容積が減少し、真空排気に掛かる手間や時間を減らす真空断熱タンクが開示されている。 Patent document 2 discloses a vacuum insulation tank that has a double vacuum insulation layer, a first and a second vacuum insulation layer, to store cryogenic liquids such as liquid hydrogen, and reduces the volume of each vacuum insulation layer, thereby reducing the effort and time required for evacuation.

特許文献３は、内槽と中間槽、及び外槽と中間槽との間に真空断熱層を備えた三重殻式真空断熱タンクであり、外槽をタンク外部の大気圧と内部の真空との圧力差に耐え得るような剛構造で形成する真空断熱タンクが開示されている。 Patent document 3 discloses a triple-shelled vacuum insulated tank with vacuum insulation layers between the inner and intermediate tanks, and between the outer and intermediate tanks, in which the outer tank is formed with a rigid structure that can withstand the pressure difference between the atmospheric pressure outside the tank and the vacuum inside.

特許文献１～３に記載されている従来技術は、タンクの内殻と外殻の間に単数又は複数の中間殻を設け、タンク外部と真空断熱層との差圧を小さくして、真空断熱層を囲繞する側部の板厚を薄くする多重殻タンクの技術に関するものではない。 The prior art described in Patent Documents 1 to 3 does not relate to the technology of a multi-shell tank in which one or more intermediate shells are provided between the inner and outer shells of the tank, reducing the pressure difference between the outside of the tank and the vacuum insulation layer, and thinning the thickness of the side walls surrounding the vacuum insulation layer.

特開昭５２-１４５８１２号公報Japanese Unexamined Patent Publication No. 52-145812 実開昭６３-９６００号公報Japanese Utility Model Application Publication No. 63-9600 実開昭６３-１５８６９５号公報Japanese Utility Model Application Publication No. 63-158695

内殻と外殻の間に真空断熱層を設けている二重殻低温タンクを大型化する場合、真空断熱層の容積が大きくなり、タンク外部の大気圧と高真空を要する真空断熱層との圧力差に耐え得るようにするために、内殻と外殻の板厚が過大となる。 When enlarging a double-shelled cryogenic tank with a vacuum insulation layer between the inner and outer shells, the volume of the vacuum insulation layer becomes larger, and the thickness of the inner and outer shells becomes excessive in order to withstand the pressure difference between the atmospheric pressure outside the tank and the vacuum insulation layer, which requires a high vacuum.

加えて、二重殻低温タンクの真空断熱層の容積が増大すると、真空断熱層を所定の高真空まで減圧排気するための大掛かりな設備が必要になるうえ、真空状態にするまで長時間を必要とするため、製作工期が延びる原因となる。 In addition, if the volume of the vacuum insulation layer of a double-shelled cryogenic tank increases, large-scale equipment is required to reduce the pressure and evacuate the vacuum insulation layer to the specified high vacuum, and it takes a long time to create a vacuum, which causes the production period to be extended.

本発明は、上記事情に鑑みてなされたもので、タンクの内殻と外殻の間に単数又は複数の中間殻を設け、タンク外部と真空断熱層との間の差圧を緩衝して、真空断熱層を形成する多重殻の各殻の側部の板厚を減らすことができる多重殻低温タンクを提供することを目的とする。 The present invention was made in consideration of the above circumstances, and aims to provide a multi-shell cryogenic tank that has one or more intermediate shells between the inner and outer shells of the tank, which buffers the pressure difference between the outside of the tank and the vacuum insulation layer, thereby reducing the thickness of the side of each shell of the multiple shells that form the vacuum insulation layer.

本発明は、
低温液体を貯蔵する内槽を形成する内殻と、
前記内殻と間隔をおいて前記内殻を囲繞して外気に接する外殻と、
前記内殻と前記外殻の間の空間を複数の断熱層に区画する１以上の中間殻とを有しており、
少なくとも１つの前記断熱層が減圧に保持されている、多重殻低温タンク
を提供する。 The present invention relates to
an inner shell forming an inner vessel for storing a cryogenic liquid;
an outer shell that is spaced apart from the inner shell and surrounds the inner shell and is in contact with outside air;
and one or more intermediate shells that divide a space between the inner shell and the outer shell into a plurality of insulating layers;
At least one of the insulating layers is maintained at a reduced pressure.

また、本発明は、
前記中間殻の数は１であり、
前記断熱層の前記内殻又は前記外殻に隣接する断熱層が真空断熱層であって、
該真空断熱層に隣接する断熱層の圧力が前記真空断熱層の圧力よりも大気圧に近い値である、前記の多重殻低温タンク
を提供する。 The present invention also provides a method for producing a semiconductor device comprising the steps of:
The number of intermediate shells is 1;
The insulation layer adjacent to the inner shell or the outer shell of the insulation layer is a vacuum insulation layer,
the pressure of the insulating layer adjacent to the vacuum insulating layer is closer to atmospheric pressure than the pressure of the vacuum insulating layer.

さらに、本発明は、
前記中間殻の数は２であり、
前記中間殻に挟まれた断熱層が真空断熱層であり、
前記内殻と第１の中間殻との間に形成され、前記内殻内の気相部の半分の圧力に減圧された第１の断熱層と、
第２の中間殻と前記外殻との間に形成され、大気圧の半分の圧力に減圧された第２の断熱層とを有している、
前記の多重殻低温タンク
を提供する。 Furthermore, the present invention provides a method for producing a
The number of intermediate shells is two;
The insulating layer sandwiched between the intermediate shells is a vacuum insulating layer,
a first insulating layer formed between the inner shell and a first intermediate shell and decompressed to half the pressure of the gas phase in the inner shell;
a second insulating layer formed between the second intermediate shell and the outer shell and depressurized to half atmospheric pressure;
The multi-shell cryogenic tank is provided.

本発明の多重殻低温タンクは、真空断熱層を形成する多重殻の各殻の側部の板厚を減らすことができる。 The multi-shell cryogenic tank of the present invention can reduce the thickness of the side of each shell of the multi-shell that forms the vacuum insulation layer.

本発明に係る多重殻低温タンクの一実施例にかかる全体構造の概略の縦断面図を示す。1 is a schematic longitudinal sectional view of an embodiment of a multi-shell cryogenic tank according to the present invention; FIG. 本発明に係る多重殻低温タンクの一実施例にかかる各断熱層の圧力を示す縦断面の模式図を示す。FIG. 2 is a schematic diagram of a vertical cross section showing the pressure of each insulating layer in one embodiment of a multi-shell cryogenic tank according to the present invention. 従来の二重殻低温タンクの各断熱層の圧力を示す縦断面の模式図を示す。1 shows a schematic diagram of a vertical cross section of a conventional double-shell cryogenic tank showing the pressures in each insulating layer.

本発明に係る多重殻低温タンクの実施形態例について図１から図３を参照しながら説明する。本発明は下記の実施形態にのみ限定されるものではない。本発明の要旨を逸脱しない範囲で下記の構成要素の省略または付加、構成要素の形状等の実施形態の変更を加えることが出来るのはもちろんである。なお、図は概略を示すもので、一部のみを描き詳細構造は省略した。 An embodiment of a multi-shell cryogenic tank according to the present invention will be described with reference to Figures 1 to 3. The present invention is not limited to the following embodiment. Of course, the following components can be omitted or added, and the shape of the components can be modified without departing from the spirit of the present invention. Note that the figures are schematic, depicting only a portion and omitting the detailed structure.

図１は、本発明に係る多重殻低温タンクの一実施例にかかる縦断面図である。多重殻低温タンク１は、低温液体９を貯蔵する内槽を形成する内殻２と、内殻２と間隔を置いて囲繞して外気に接する外殻３と、内殻２と外殻３の間の空間を３つの断熱層に区画する２つの中間殻４、５とを有している。すなわち、第１の中間殻４と第２の中間殻５とが設けられた多重殻低温タンク１の事例を示している。
多重殻低温タンク１は、図１に示すように、コンクリート製の基礎１２上に底板１３が設けられ、この底板１３上にパーライトコンクリート等の底部断熱材１１を介し、底板１０が設けられ、底板１０上に内殻側部２ａが立設されている。また、底板１３上の底部断熱材１１よりも外側に第１の中間殻側部４ａと第２の中間殻側部５ａと外殻側部３ａが立設されている。
低温液体９は、例えばマイナス２５３℃の液体水素である。
内殻２はステンレス鋼板、第１の中間殻４と第２の中間殻５は低温用鋼板、外殻３は軟鋼板によって形成することができる。なお、内殻２、第１の中間殻４、第２の中間殻５、外殻３の各殻をＣＦＲＰ（炭素繊維強化プラスチック）で形成しても良い。
内殻屋根２ｂ、第１の中間殻屋根４ｂ、第２の中間殻屋根５ｂ、外殻屋根３ｂの屋根形状は、何れも半球状又は欠球状の屋根を採用することができる。図１では、欠球状よりも必要板厚が薄い半球状の屋根形状を採用する事例を示している。
なお、多重殻低温タンク１は、図１に示すような平底円筒形だけでなく、縦置円筒形、横置円筒形、球形等の形状の多重殻低温タンク１とすることもできる。また、図１に示すような地上式だけでなく、敷地にピットを掘って、所定の高さを埋設した半地下式、或いは地中に埋設した地下式、或いは盛土式の多重殻低温タンク１とすることもできる。 1 is a longitudinal sectional view of an embodiment of a multi-shell cryogenic tank according to the present invention. The multi-shell cryogenic tank 1 has an inner shell 2 forming an inner tank for storing a cryogenic liquid 9, an outer shell 3 surrounding the inner shell 2 at a distance therefrom and in contact with the outside air, and two intermediate shells 4 and 5 dividing the space between the inner shell 2 and the outer shell 3 into three insulating layers. That is, the example of the multi-shell cryogenic tank 1 provided with a first intermediate shell 4 and a second intermediate shell 5 is shown.
As shown in Fig. 1, the multi-shell cryogenic tank 1 has a bottom plate 13 provided on a concrete foundation 12, a bottom plate 10 provided on the bottom plate 13 via a bottom insulation material 11 such as perlite concrete, and an inner shell side portion 2a standing on the bottom plate 10. Also, a first intermediate shell side portion 4a, a second intermediate shell side portion 5a, and an outer shell side portion 3a are standing on the bottom plate 13 outside the bottom insulation material 11.
The cryogenic liquid 9 is, for example, liquid hydrogen at minus 253 degrees Celsius.
The inner shell 2 can be made of a stainless steel plate, the first intermediate shell 4 and the second intermediate shell 5 can be made of a low-temperature steel plate, and the outer shell 3 can be made of a mild steel plate. Each of the inner shell 2, the first intermediate shell 4, the second intermediate shell 5, and the outer shell 3 may be made of CFRP (carbon fiber reinforced plastic).
The roof shapes of the inner shell roof 2b, the first intermediate shell roof 4b, the second intermediate shell roof 5b, and the outer shell roof 3b can all be hemispherical or partially spherical. Figure 1 shows an example of a hemispherical roof shape, which requires a thinner plate thickness than a partially spherical roof.
The multi-shell cryogenic tank 1 can be not only a flat-bottom cylindrical tank as shown in Fig. 1, but also a vertically-placed cylindrical tank, a horizontally-placed cylindrical tank, a spherical tank, etc. Also, in addition to the above-ground type as shown in Fig. 1, the multi-shell cryogenic tank 1 can be a semi-underground type buried at a predetermined height in a pit dug on the site, an underground type buried in the ground, or a mound type.

内殻２と外殻３の間に２つの中間殻４，５が設けられているので、３つの断熱層があることになる。例として、内殻２と第１の中間殻４（内側の中間殻）との間を第１の断熱層６とし、第１の中間殻４と第２の中間殻５（外側の中間殻）との間を高真空を要する真空断熱層７とし、第２の中間殻５と外殻３との間を第２の断熱層８とすることができる。
第１の断熱層６、真空断熱層７、第２の断熱層８の各断熱層は、独立した空間として区画され、各断熱層にポリウレタンフォーム（ＰＵＦ）や粒状パーライト等の断熱材を充填することができる。各断熱層間において断熱材や気体の移動はない。各断熱層において、減圧を行うことができる。第１の断熱層６、真空断熱層７、第２の断熱層８のいずれかまたは複数に断熱材を充填しない構造とすることもできる。
なお、多重殻低温タンク１の真空断熱層７を囲繞する第１の中間殻４と第２の中間殻５の内側又は外側あるいはその両方に輻射熱遮蔽材を設けたり、遮熱塗装を施して、外部からの輻射熱により、低温液体９が加熱されることを抑制することができる。 Since two intermediate shells 4, 5 are provided between the inner shell 2 and the outer shell 3, there are three insulation layers. For example, a first insulation layer 6 can be provided between the inner shell 2 and the first intermediate shell 4 (the inner intermediate shell), a vacuum insulation layer 7 requiring a high vacuum can be provided between the first intermediate shell 4 and the second intermediate shell 5 (the outer intermediate shell), and a second insulation layer 8 can be provided between the second intermediate shell 5 and the outer shell 3.
Each of the first insulation layer 6, the vacuum insulation layer 7, and the second insulation layer 8 is partitioned as an independent space, and each insulation layer can be filled with an insulation material such as polyurethane foam (PUF) or granular perlite. There is no movement of insulation material or gas between the insulation layers. Pressure can be reduced in each insulation layer. It is also possible to have a structure in which insulation material is not filled in any one or more of the first insulation layer 6, the vacuum insulation layer 7, and the second insulation layer 8.
In addition, by providing a radiant heat shielding material or applying a heat insulating paint to the inside or outside or both of the first intermediate shell 4 and the second intermediate shell 5 surrounding the vacuum insulation layer 7 of the multi-shelled cryogenic tank 1, the heating of the cryogenic liquid 9 by radiant heat from the outside can be prevented.

図２は、本発明に係る多重殻低温タンクの一実施例にかかる各部の圧力を示すタンクの縦断面の模式図を示す。各部にかかる圧力を理解するために、圧力分布の仮想例を下記に示す。圧力はゲージ圧とする。なお、各部の圧力はこの例に限定されるものでは一切なく、本発明の技術的思想に基づいて各種の変更が可能である。
内殻２の気相部の圧力をＰ１とする。通常、Ｐ１は、内殻２が貯蔵する低温液体９の種類に応じた設計圧力とし、内殻２内に液体水素を貯蔵する場合は、０．０２ＭＰａの圧力に保たれる。
内殻２と第１の中間殻４との間に形成される第１の断熱層６の圧力Ｐ２は、例えば、Ｐ１の半分の圧力に減圧した圧力とすることができる。
第１の中間殻４と第２の中間殻５との間に形成された真空断熱層７の圧力Ｐ３は、概ね大気圧に相当する圧力を減圧した圧力とすることができる。
第２の中間殻５と外殻３との間に形成される第２の断熱層８の圧力のＰ４は、大気圧の半分に減圧した圧力とすることができる。 2 is a schematic diagram of a vertical cross section of a tank showing the pressures of each part in one embodiment of a multi-shell cryogenic tank according to the present invention. In order to understand the pressures acting on each part, a hypothetical example of pressure distribution is shown below. The pressures are gauge pressures. Note that the pressures of each part are not limited to this example, and various modifications are possible based on the technical concept of the present invention.
The pressure of the gas phase of the inner shell 2 is designated as P1. Normally, P1 is a design pressure according to the type of cryogenic liquid 9 stored in the inner shell 2, and when liquid hydrogen is stored in the inner shell 2, the pressure of P1 is kept at 0.02 MPa.
The pressure P2 of the first insulating layer 6 formed between the inner shell 2 and the first intermediate shell 4 can be reduced to, for example, half the pressure of P1.
The pressure P3 of the vacuum insulation layer 7 formed between the first intermediate shell 4 and the second intermediate shell 5 can be set to a pressure obtained by reducing a pressure roughly equivalent to atmospheric pressure.
The pressure P4 of the second insulating layer 8 formed between the second intermediate shell 5 and the outer shell 3 can be reduced to half the atmospheric pressure.

多重殻低温タンク１の内殻側部２ａ、第１の中間殻側部４ａ、第２の中間殻側部５ａ、外殻側部３ａに作用する差圧力は、以下の通りである。
内殻側部２ａには、Ｐ１－Ｐ２＝Ｐ１－Ｐ１/２＝Ｐ１／２の差圧力が作用する。
Ｐ２＝Ｐ１／２であるので、第１の中間殻側部４ａには、Ｐ２－（－Ｐ３）＝Ｐ１／２＋Ｐ３の差圧力が作用する。
第２の中間殻側部５ａには、－Ｐ３－（－Ｐ４）＝－Ｐ３＋Ｐ３／２＝－Ｐ３／２の差圧力が作用する。
外殻側部３ａは、外気に接しているため、－Ｐ４＝－Ｐ３／２の差圧力が作用する。 The differential pressures acting on the inner shell side 2a, the first intermediate shell side 4a, the second intermediate shell side 5a, and the outer shell side 3a of the multi-shell cryogenic tank 1 are as follows:
A differential pressure of P1-P2=P1-P1/2=P1/2 acts on the inner shell side portion 2a.
Since P2=P1/2, a differential pressure of P2-(-P3)=P1/2+P3 acts on the first intermediate shell side portion 4a.
A differential pressure of -P3-(-P4)=-P3+P3/2=-P3/2 acts on the second intermediate shell side portion 5a.
Since the outer shell side portion 3a is in contact with the outside air, a differential pressure of -P4 = -P3/2 acts on it.

図３は、従来の二重殻低温タンクの各断熱層の圧力を示す縦断面の模式図を示す。内殻２２と外殻２３の２層構造で、中間殻はなく、同じ材料、貯蔵液、断熱材を使用し、同じ直径、高さの二重殻タンク２１の内殻２２と外殻２３の間を減圧して真空断熱層２４とした場合に、内殻側部２２ａと外殻側部２３ａに作用する差圧力は、以下の通りとなる。
なお、二重殻低温タンク２１の内殻２２の気相部の圧力は、多重殻低温タンク１と同じＰ１の圧力に保持され、真空断熱層２４の圧力は、多重殻低温タンク１の圧力と同じＰ３まで減圧する。
内殻側部２２ａには、Ｐ１－（－Ｐ３）＝Ｐ１＋Ｐ３の差圧力が作用する。
外殻側部２３ａは、外気に接しているため、真空断熱層２４の圧力－Ｐ３の差圧力が作用することになる。 Fig. 3 is a schematic diagram of a vertical cross section showing the pressure of each insulation layer of a conventional double-shelled cryogenic tank. When a double-shelled tank 21 has a two-layer structure of an inner shell 22 and an outer shell 23, no intermediate shell, uses the same materials, stored liquid, and insulation materials, and has the same diameter and height, and the space between the inner shell 22 and the outer shell 23 is reduced in pressure to form a vacuum insulation layer 24, the differential pressure acting on the inner shell side 22a and the outer shell side 23a is as follows:
The pressure of the gas phase of the inner shell 22 of the double-shelled cryogenic tank 21 is maintained at the same pressure P1 as that of the multi-shelled cryogenic tank 1, and the pressure of the vacuum insulation layer 24 is reduced to P3, the same as that of the multi-shelled cryogenic tank 1.
A differential pressure of P1-(-P3)=P1+P3 acts on the inner shell side portion 22a.
Since the outer shell side portion 23a is in contact with the outside air, a pressure difference of the vacuum insulation layer 24 -P3 acts on it.

本発明の多重殻低温タンク１の内殻側部２ａ、外殻側部３ａと二重殻タンク２１の内殻側部２２ａ、外殻側部２３ａに作用する差圧力をそれぞれ比較した場合について述べる。
従来の二重殻タンク２１の内殻側部２２ａに作用する差圧力Ｐ１＋Ｐ３と、本発明の多重殻低温タンク１の内殻側部２ａに作用する差圧力Ｐ１/２を比較すると、二重殻タンク２１の内殻側部２２ａにＰ１/２＋Ｐ３の分だけ余分に差圧力が掛かることになり、その差に応じて内殻側部の板厚を厚くする必要がある。
同様に、二重殻タンク２１の外殻側部２３ａに作用する差圧力－Ｐ３と、本発明の多重殻低温タンク１の外殻側部３ａに作用する差圧力－Ｐ３／２を比較すると、二重殻タンク２１の外殻側部２３ａに作用する差圧が多重殻低温タンク１の外殻側部３ａに作用する差圧の２倍となり、その差に応じて外殻側部の板厚を厚くする必要がある。 A comparison of the differential pressure acting on the inner shell side 2a and outer shell side 3a of the multi-shell cryogenic tank 1 of the present invention and the inner shell side 22a and outer shell side 23a of the double-shell tank 21 will be described.
Comparing the differential pressure P1+P3 acting on the inner shell side 22a of a conventional double-shell tank 21 with the differential pressure P1/2 acting on the inner shell side 2a of the multi-shell cryogenic tank 1 of the present invention, an additional differential pressure of P1/2+P3 is applied to the inner shell side 22a of the double-shell tank 21, and the plate thickness of the inner shell side needs to be increased accordingly.
Similarly, when comparing the pressure difference -P3 acting on the outer shell side 23a of the double-shelled tank 21 with the pressure difference -P3/2 acting on the outer shell side 3a of the multi-shelled cryogenic tank 1 of the present invention, the pressure difference acting on the outer shell side 23a of the double-shelled tank 21 is twice the pressure difference acting on the outer shell side 3a of the multi-shelled cryogenic tank 1, and the plate thickness of the outer shell side needs to be increased according to this difference.

また、従来の二重殻タンク２１の真空断熱層２４を囲う内殻側部２２ａと外殻側部２３ａに相当する、本発明の多重殻低温タンク１の真空断熱層７を囲う第１の中間殻側部４ａ（内側）、第２の中間殻側部５ａ（外側）に作用する差圧力をそれぞれ比較した場合についても述べる。
二重殻タンク２１の内殻側部２２ａに作用する差圧力Ｐ１＋Ｐ３と、本発明の多重殻低温タンク１の第１の中間殻側部４ａに作用する差圧力Ｐ１／２＋Ｐ３を比較すると、二重殻タンク２１の内殻側部２２ａにＰ１/２の分だけ余分に差圧力が掛かることになり、その差に応じて側部の板厚を厚くする必要がある。
同様に、二重殻タンク２１の外殻側部２３ａに作用する差圧力－Ｐ３と、本発明の多重殻低温タンク１の第２の中間殻側部５ａに作用する差圧力－Ｐ３／２を比較すると、二重殻タンク２１の外殻側部２３ａに作用する差圧が多重殻低温タンク１の第２の中間殻側部５ａに作用する差圧の２倍となり、その差に応じて側部の板厚を厚くする必要がある。 We will also describe a comparison of the differential pressures acting on the first intermediate shell side 4a (inner side) and the second intermediate shell side 5a (outer side) surrounding the vacuum insulation layer 7 of the multi-shelled low-temperature tank 1 of the present invention, which correspond to the inner shell side 22a and the outer shell side 23a surrounding the vacuum insulation layer 24 of the conventional double-shelled tank 21.
Comparing the differential pressure P1+P3 acting on the inner shell side 22a of the double-shell tank 21 with the differential pressure P1/2+P3 acting on the first intermediate shell side 4a of the multi-shell cryogenic tank 1 of the present invention, an extra differential pressure of P1/2 is applied to the inner shell side 22a of the double-shell tank 21, and the thickness of the side plate needs to be increased according to this difference.
Similarly, when comparing the pressure difference -P3 acting on the outer shell side 23a of the double-shell tank 21 with the pressure difference -P3/2 acting on the second intermediate shell side 5a of the multi-shell cryogenic tank 1 of the present invention, the pressure difference acting on the outer shell side 23a of the double-shell tank 21 is twice the pressure difference acting on the second intermediate shell side 5a of the multi-shell cryogenic tank 1, and the thickness of the side plate needs to be increased in accordance with this difference.

以上より、本発明の多重殻低温タンク１は、従来の二重殻タンク２１と比較し、真空断熱層を形成する各殻の側部の板厚を減らせるという効果を有しており、特に内殻の板厚軽減において、絶大な効果がある。 As described above, the multi-shell cryogenic tank 1 of the present invention has the advantage of reducing the thickness of the sides of each shell that form the vacuum insulation layer compared to the conventional double-shell tank 21, and is particularly effective in reducing the thickness of the inner shell.

以上、本発明の一実施態様につき述べたが、本発明はこの実施態様に限定されるものではなく、本発明の技術的思想に基づいて各種の変形及び変更が可能である。
例えば、本発明に係る多重殻低温タンク１は、第１の断熱層６を気相部の半分の圧力Ｐ２に減圧に保持し、第２の断熱層８を大気圧の半分の圧力Ｐ４に減圧に保持しているが、気相部や大気の半分の圧力でなくても良く、気相部や大気の数分の１の圧力とすることで、第１の中間殻側部４ａと第２の中間殻側部５ａに作用する差圧力が減少し、二重殻タンク２１と比較して真空断熱層を形成する各殻の側部の板厚を薄くすることができる。 Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes are possible based on the technical concept of the present invention.
For example, the multi-shelled low-temperature tank 1 of the present invention maintains the first insulating layer 6 at a reduced pressure of P2, which is half the pressure of the gas phase, and the second insulating layer 8 at a reduced pressure of P4, which is half the atmospheric pressure, but the pressure does not have to be half that of the gas phase or atmosphere.By setting the pressure to a fraction of that of the gas phase or atmosphere, the differential pressure acting on the first intermediate shell side portion 4a and the second intermediate shell side portion 5a is reduced, and the plate thickness of the sides of each shell forming the vacuum insulation layer can be made thinner than in the double-shelled tank 21.

本発明は、図１、図２の３層の中間層構造の多重殻低温タンクの実施態様に限らず、種々の構成を適用することが可能である。例えば、図示しないが、１つの中間殻を設けた２層の中間層構造の三重殻低温タンクとしたり、３以上の中間殻を設けた４層以上の中間層構造の多重殻低温タンクとすることも可能である。
２層の中間層構造の三重殻低温タンクとする場合、内殻と中間殻で真空断熱層をはさみ、真空断熱層に隣り合う断熱層の圧力を大気圧の半分程度の圧力とすることで、使用する側部の材料の板厚を薄くすることができる。また、外殻と中間殻で真空断熱層を形成する場合は、真空断熱層に隣り合う断熱層の圧力を気相部の半分の圧力とすることで、使用する側部の材料の板厚を薄くすることができる。
４層以上の中間層構造の多重殻低温タンクとする場合は、真空断熱層７から外殻３にかけて形成された複数の断熱層を段階的に減圧し、外殻３に向かうにつれて断熱層の圧力を大気圧に近い値に近付けることで、各々の断熱層を形成する側部に作用する差圧力が減少し、側部の板厚を薄くすることができる。また、同様に、内殻２から真空断熱層７にかけて形成された複数の断熱層を段階的に減圧し、内殻２に向かうにつれて断熱層の圧力を気相部の圧力に近い値に近付けることで、各々の断熱層を形成する側部に作用する差圧力が減少し、側部の板厚を薄くすることもできる。 The present invention is not limited to the embodiment of the multi-shell cryogenic tank having a three-layer intermediate layer structure shown in Figures 1 and 2, and various configurations can be applied. For example, although not shown, it is possible to use a triple-shell cryogenic tank having a two-layer intermediate layer structure with one intermediate shell, or a multi-shell cryogenic tank having a four-layer or more intermediate layer structure with three or more intermediate shells.
In the case of a triple-shell cryogenic tank with a two-layer intermediate layer structure, the thickness of the material used for the sides can be reduced by sandwiching a vacuum insulation layer between the inner and intermediate shells and setting the pressure of the insulation layer adjacent to the vacuum insulation layer to about half of atmospheric pressure. Also, in the case of forming a vacuum insulation layer between the outer and intermediate shells, the thickness of the material used for the sides can be reduced by setting the pressure of the insulation layer adjacent to the vacuum insulation layer to half the pressure of the gas phase.
In the case of a multi-shell cryogenic tank with a four or more intermediate layer structure, the pressure difference acting on the side portions forming each insulating layer can be reduced and the plate thickness of the side portions can be made thinner by gradually reducing the pressure in the multiple insulating layers formed from the vacuum insulating layer 7 to the outer shell 3 and bringing the pressure of the insulating layers closer to atmospheric pressure toward the outer shell 3. Similarly, the pressure difference acting on the side portions forming each insulating layer can be reduced and the plate thickness of the side portions can be made thinner by gradually reducing the pressure in the multiple insulating layers formed from the inner shell 2 to the vacuum insulating layer 7 and bringing the pressure of the insulating layers closer to the pressure of the gas phase toward the inner shell 2.

また、本発明の多重殻低温タンク１の内殻２が貯蔵する低温液体９としては、液体水素に限らず、ＬＰＧやＬＮＧ、液体アンモニア等、種々の液体を使用することが可能である。 The cryogenic liquid 9 stored in the inner shell 2 of the multi-shell cryogenic tank 1 of the present invention is not limited to liquid hydrogen, and various other liquids such as LPG, LNG, and liquid ammonia can be used.

上記の本発明の本実施形態の多重殻低温タンク１は、下記の効果を少なくとも１以上有している。
従来と比べて、真空断熱層と隣り合う断熱層との差圧力を小さくすることにより、真空断熱層を形成する側部の板厚を減らすことができる。つまり、従来より薄い板厚で座屈に対抗する構造とすることができる。
容積が小さい断熱層を複数設ける構造とすることで、従来と比べ、全体として断熱層の幅を広くとることができ、結果として、低温タンクの大型化が実現できる。また、各断熱層を従来より小さい容積とすることで、減圧排気する設備を従来より小型化できる。
多重殻の各殻の側部を形成する鋼板の板厚を薄くすることにより、各殻の側部を厚板で形成する場合と比較して、鋼板相互の溶接が容易である。 The multi-shell cryogenic tank 1 of this embodiment of the present invention has at least one of the following effects.
By reducing the pressure difference between the vacuum insulation layer and the adjacent insulation layer compared to the conventional method, the thickness of the plate on the side that forms the vacuum insulation layer can be reduced. In other words, a structure that resists buckling can be achieved with a thinner plate thickness than before.
By using multiple small-volume insulation layers, the width of the insulation layers can be made wider overall compared to conventional methods, which results in a larger cryogenic tank. Also, by making each insulation layer smaller in volume than conventional methods, the equipment for decompression and exhaust can be made smaller than conventional methods.
By making the steel plates forming the sides of each shell of the multi-shell structure thinner, welding of the steel plates to each other is easier than when the sides of each shell are made of thick plates.

なお、この発明は上記の実施形態に限定されるものではなく、その要旨を逸脱しない範囲で種々の構成変更が可能である。 This invention is not limited to the above embodiment, and various configuration changes are possible without departing from the spirit of the invention.

１多重殻低温タンク
２内殻
２ａ内殻側部
２ｂ内殻屋根部
３外殻
３ａ外殻側部
３ｂ外殻屋根部
４第１の中間殻
４ａ第１の中間殻側部
４ｂ第１の中間殻屋根部
５第２の中間殻
５ａ第２の中間殻側部
５ｂ第２の中間殻屋根部
６第１の断熱層
７真空断熱層
８第２の断熱層
９低温液体
１０底板
１１底部断熱材
１２基礎
１３底板

２１二重殻低温タンク
２２内殻
２２ａ内殻側部
２３外殻
２３ａ外殻側部
２４真空断熱層

Ｐ１内殻２、２２の気相部の圧力
Ｐ２第１の断熱層６の圧力
Ｐ３真空断熱層７、２４の圧力
Ｐ４第２の断熱層８の圧力

1. Multi-hull cryogenic tank
2. Inner shell
2a Inner shell side portion 2b Inner shell roof portion 3 Outer shell 3a Outer shell side portion 3b Outer shell roof portion 4 First intermediate shell
4a: first intermediate shell side portion 4b: first intermediate shell roof portion 5: second intermediate shell 5a: second intermediate shell side portion 5b: second intermediate shell roof portion 6: first insulation layer 7: vacuum insulation layer 8: second insulation layer 9: cryogenic liquid 10: bottom plate 11: bottom insulation material 12: foundation 13: bottom plate

21 Double-shelled cryogenic tank 22 Inner shell 22a Inner shell side 23 Outer shell 23a Outer shell side 24 Vacuum insulation layer

P1: Pressure of the gas phase of the inner shell 2, 22 P2: Pressure of the first insulating layer 6 P3: Pressure of the vacuum insulating layers 7, 24 P4: Pressure of the second insulating layer 8

Claims

an inner shell forming an inner vessel for storing a cryogenic liquid;
an outer shell that is spaced apart from the inner shell and surrounds the inner shell and is in contact with outside air;
and an intermediate shell that divides a space between the inner shell and the outer shell into two insulating layers.
A multi-shell cryogenic tank, wherein the insulation layer adjacent to the outer shell among the insulation layers is a vacuum insulation layer, and the pressure of the insulation layer adjacent to the vacuum insulation layer is half the design pressure for the type of cryogenic liquid stored in the inner shell .

an inner shell forming an inner vessel for storing a cryogenic liquid;
an outer shell that is spaced apart from the inner shell and surrounds the inner shell and is in contact with outside air;
The space between the inner shell and the outer shell is divided into three insulation layers.
A multi-shell cryogenic tank, wherein the insulating layer sandwiched between the intermediate shells is a vacuum insulating layer, and the insulating layers adjacent to the vacuum insulating layer are a first insulating layer formed between the inner shell and a first intermediate shell and a second insulating layer formed between a second intermediate shell and the outer shell, and the first insulating layer and the second insulating layer are respectively maintained at reduced pressure relative to a design pressure corresponding to the type of cryogenic liquid stored in the inner shell and atmospheric pressure.

The first insulation layer is depressurized to half the design pressure,
3. The multi-shell cryogenic tank of claim 2 , wherein said second insulation layer is evacuated to half atmospheric pressure.