Multi-hull cryogenic tank

Abstract

To provide a multi-shell low temperature tank which includes a multiple shell forming a vacuum heat insulation layer and enables reduction of the plate thickness of the side portion of each of the shells.SOLUTION: A multi-shell low temperature tank is provide, having : an inner shell 2 forming an inner tank storing low temperature liquid 9; an outer shell 3 encircling the inner shell 2 and contacting the outside air with an interval from the inner shell 2; and two middle shells 4, 5 sectioning a space between the inner shell 2 and the outer shell 3 into a plurality of heat insulation layers. In the multi-shell low temperature tank, a heat insulation layer between the middle shells 4, 5 is a vacuum heat insulation layer 7, the multi-shell low temperature tank has: a first heat insulation layer 6 which is formed between the inner shell 2 and the first middle shell 4 and depressurized to half of a gas phase portion in the inner shell 2; and a second heat insulation layer 8 which is formed between the second middle shell 5 and the outer shell 3 and is depressurized to half of the atmospheric pressure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a multi-shell cryogenic tank. [Background technology]

[0002] In double-shell cryogenic tanks with a vacuum insulation layer between the inner and outer shells, the thickness of the inner and outer shells must be designed so that they can withstand the pressure difference between the atmospheric pressure outside the tank and the high vacuum of the vacuum insulation layer between the inner and outer shells.

[0003] In addition, in the manufacture of a double-shelled cryogenic tank with a vacuum insulation layer between the inner and outer shells, it takes time and effort to evacuate the space between the inner and outer shells until a specified high vacuum is reached. In particular, in the case of a large double-shelled cryogenic tank, the volume of the vacuum insulation layer between the inner and outer shells increases, so the time and effort required for evacuating the space increases significantly.

[0004] Conventional techniques for multi-shell tanks, including double-shell tanks, have been disclosed so far (Patent Documents 1 to 3).

[0005] Patent Document 1 discloses a multi-shell high-pressure tank in which a plurality of storage chambers are formed in a compartment and capable of storing fluids at various pressures.

[0006] Patent Document 2 discloses a vacuum insulated tank that has a double vacuum insulation layer, consisting of a first and a second vacuum insulation layer, for storing cryogenic liquids such as liquid hydrogen, thereby reducing the volume of each vacuum insulation layer and reducing the effort and time required for evacuation.

[0007] Patent Document 3 discloses a triple-shell vacuum insulated tank having vacuum insulation layers between an inner tank and an intermediate tank, and between an outer tank and an intermediate tank, in which the outer tank is formed with a rigid structure capable of withstanding the pressure difference between the atmospheric pressure outside the tank and the vacuum inside.

[0008] 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, thereby 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. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 52-145812 [Patent Document 2] Japanese Utility Model Application Publication No. 63-9600 [Patent Document 3] Japanese Utility Model Application Publication No. 63-158695 Summary of the Invention [Problem to be solved by the invention]

[0010] When a double-shelled cryogenic tank with a vacuum insulation layer between the inner and outer shells is enlarged, the volume of the vacuum insulation layer becomes large, 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.

[0011] 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 a specified high vacuum, and it takes a long time to create a vacuum state, which causes the production period to be extended.

[0012] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a multi-shelled low-temperature tank in which one or more intermediate shells are provided between the inner and outer shells of the tank, thereby buffering the pressure difference between the outside of the tank and the vacuum insulation layer and reducing the plate thickness of the sides of each of the multiple shells that form the vacuum insulation layer. [Means for solving the problem]

[0013] 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; A multi-shell cryogenic tank, at least one of said insulating layers being maintained at reduced pressure. to provide.

[0014] 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 multi-shell cryogenic tank, wherein the pressure of the insulation layer adjacent to the vacuum insulation layer is closer to atmospheric pressure than the pressure of the vacuum insulation layer. to provide.

[0015] Furthermore, the present invention relates to 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 is formed between the second intermediate shell and the outer shell and is decompressed to half atmospheric pressure. Said multi-shell cryogenic tank to provide. Effect of the Invention

[0016] The multi-shell cryogenic tank of the present invention can reduce the thickness of the side of each of the multiple shells that form the vacuum insulation layer. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic longitudinal sectional view of an embodiment of a multi-shell cryogenic tank according to the present invention; FIG. [Diagram 2] 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. [Diagram 3]1 shows a schematic diagram of a vertical cross section of a conventional double-shell cryogenic tank showing the pressures in each insulating layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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 shapes of the components can be modified without departing from the gist of the present invention. Note that the figures are schematic, depicting only a portion and omitting the detailed structure.

[0019] 1 is a longitudinal sectional view of one 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 with a bottom insulation material 11 such as perlite concrete interposed therebetween, and an inner shell side portion 2a standing upright 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 standing upright 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 stainless steel plate, the first intermediate shell 4 and the second intermediate shell 5 can be made of low-temperature steel plate, and the outer shell 3 can be made of 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 shape. 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 aboveground type as shown in Fig. 1, the multi-shell cryogenic tank 1 can be a semi-underground type buried at a specified height in a pit dug on the site, an underground type buried in the ground, or a mound type.

[0020] 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 each insulation layer. 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.

[0021] Figure 2 shows a schematic diagram of a vertical cross section of a tank showing the pressure at each part in one embodiment of a multi-shell cryogenic tank according to the present invention. In order to understand the pressure at each part, a hypothetical example of pressure distribution is shown below. The pressure is a gauge pressure. Note that the pressure at each part is not limited to this example at all, 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.

[0022] 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.

[0023] Figure 3 shows 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 with 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, the differential pressure of the vacuum insulation layer 24 -P3 acts on it.

[0024] 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 thickness of the outer shell side needs to be increased according to this difference.

[0025] 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 plate thickness of the side 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.

[0026] As described above, the multi-shell low-temperature tank 1 of the present invention has the advantage of reducing the thickness of the sides of each shell that forms the vacuum insulation layer, compared to the conventional double-shell tank 21, and is particularly effective in reducing the thickness of the inner shell.

[0027] 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 P2, which is half the pressure of the gas phase, and the second insulating layer 8 at a reduced pressure 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 the pressure 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.

[0028] 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 or more layer 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 in the multiple insulation layers formed from the vacuum insulation layer 7 to the outer shell 3 can be gradually reduced, and the pressure in the insulation layers can be brought closer to atmospheric pressure toward the outer shell 3, thereby reducing the differential pressure acting on the side portions forming each insulation layer and making the plate thickness of the side portions thinner. Similarly, the pressure in the multiple insulation layers formed from the inner shell 2 to the vacuum insulation layer 7 can be gradually reduced, and the pressure in the insulation layers can be brought closer to the pressure of the gas phase toward the inner shell 2, thereby reducing the differential pressure acting on the side portions forming each insulation layer and making the plate thickness of the side portions thinner.

[0029] Furthermore, 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.

[0030] 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 conventional methods. 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.

[0031] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made to the configuration without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0032] 1. Multi-hull cryogenic tank 2 Inner shell 2a Inner shell side 2b Inner shell roof 3. Outer shell 3a Outer shell side 3b Outer shell roof section 4. First intermediate shell 4a First intermediate shell side 4b First intermediate shell roof section 5 Second intermediate shell 5a Second intermediate shell side 5b Second intermediate shell roof section 6 First insulation layer 7 Vacuum insulation layer 8 Second Insulation Layer 9. Cryogenic Liquids 10 Bottom plate 11 Bottom insulation 12 Basics 13 Bottom plate 21 Double-hulled 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 shells 2 and 22 P2 pressure of first insulating layer 6 P3 Pressure of vacuum insulation layers 7 and 24 P4 Pressure of the second insulating layer 8

Claims

1. 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.

2. 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.

3. The first insulation layer is decompressed 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.

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