Low-temperature liquefied gas storage tank

Abstract

The low-temperature liquefied gas storage tank is a flat-bottomed cylindrical tank having a three-layer shell structure, and comprises: an inner tank for storing low-temperature liquefied gas; the middle groove surrounds the inner groove through an inner side cold insulation layer; and an outer tank surrounding the intermediate tank with an outer side cold insulation layer. The intermediate groove is made of low-temperature steel.

Description

Technical Field

[0001] The present disclosure relates to a tank including an inner tank, an intermediate tank, and an outer tank and storing a cryogenic liquefied gas. Background Art

[0002] As a tank for storing low-temperature liquefied gas such as liquefied hydrogen or liquefied natural gas, a flat bottom tank having a multilayer shell structure is known. As a multilayer shell tank, a tank having a three-layer shell structure is also known, which includes an inner tank, an intermediate tank surrounding the inner tank, and an outer tank surrounding the intermediate tank (for example, Patent Document 1).

[0003] Since the triple shell tank can double the cold insulation layer between the inner tank and the middle tank and between the middle tank and the outer tank, it can have excellent thermal insulation and is well suited for storing extremely low temperature liquefied gas. However, in the case of a triple shell tank, since the tank needs to be constructed three times, the tank will be larger. Therefore, there is a problem that the land area required for the construction of the triple shell tank will also increase.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent document 1: Japanese Patent Publication No. 55-20937 Summary of the invention

[0007] An object of the present disclosure is to provide a cryogenic liquefied gas storage tank that can achieve compactness of the tank and reduce the land area required for tank construction.

[0008] A low-temperature liquefied gas storage tank involved in one aspect of the present disclosure is a tank of a flat-bottom cylindrical three-layer shell structure, which includes: an inner tank for storing low-temperature liquefied gas; an intermediate tank, the inner tank is surrounded by an inner cold insulation layer; and an outer tank, the intermediate tank is surrounded by an outer cold insulation layer; wherein the intermediate tank is formed of low-temperature steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view showing a triple shell tank according to the first embodiment of the cryogenic liquefied gas storage tank disclosed in the present invention.

[0010] Figure 2 It is a cross-sectional view showing a main part of a triple shell tank according to a second embodiment of the present disclosure.

[0011] Figure 3 It is a cross-sectional view showing a triple shell tank according to a third embodiment of the present disclosure.

[0012] Figure 4 It is a cross-sectional view showing a triple shell tank according to a fourth embodiment of the present disclosure.

[0013] Figure 5 It is a cross-sectional view showing a triple shell tank according to a fifth embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of the cryogenic liquefied gas storage tank involved in the present disclosure will be described in detail with reference to the accompanying drawings. The cryogenic liquefied gas storage tank disclosed in the present disclosure is a tank for storing cryogenic liquefied gas and is a ground-fixed flat-bottomed tank. The cryogenic liquefied gas stored is, for example, liquefied hydrogen, liquid helium, liquid nitrogen, liquefied natural gas or liquefied petroleum gas. In the following embodiments, a three-layer shell tank is exemplified as a cryogenic liquefied gas storage tank.

[0015] [First embodiment]

[0016] Figure 1 1 is a cross-sectional view showing a triple shell tank 1 according to a first embodiment of the present disclosure. Here, a triple shell tank 1 storing liquefied hydrogen LH is exemplified. Figure 1 It is a longitudinal sectional view of a three-layer shell tank 1. The three-layer shell tank 1 comprises: a tank foundation 10; a tank body 1T including an outer tank 2, an intermediate tank 3 and an inner tank 4 vertically arranged on the tank foundation 10; and a surge tank 6 attached to the tank body.

[0017] The tank foundation 10 is a concrete layer constituting the foundation part of the triple shell tank 1. The tank foundation 10 has a size larger than the outer diameter of the outer tank 2. The tank body 1T is in the form of a flat-bottomed cylindrical shape, and the outer tank 2, the intermediate tank 3, and the inner tank 4 all have a circular shape when viewed from above, and are arranged in a concentric circle. The inner tank 4 is a tank for actually storing liquefied hydrogen LH. The intermediate tank 3 surrounds the inner tank 4 via the inner cold insulation layer 11. The outer tank 2 surrounds the intermediate tank 3 via the outer cold insulation layer 12.

[0018] The outer tank 2 is a closed body made of metal such as carbon steel, and includes an outer tank bottom plate 21, an outer tank side plate 22, and an outer tank top 23. The outer tank bottom plate 21 is laid directly above the tank foundation 10 and has a disc shape. The outer tank side plate 22 is erected from the periphery of the outer tank bottom plate 21 and has a cylindrical shape. The outer tank top 23 is installed on the upper end of the outer tank side plate 22 in a manner of covering the upper opening of the cylindrical outer tank side plate 22 and has a dome shape.

[0019] The middle tank 3 is a closed body made of low temperature steel, which includes a middle tank bottom plate 31, a middle tank side plate 32 and a middle tank top 33. The middle tank bottom plate 31 has a disk shape with a smaller diameter than the outer tank bottom plate 21. The middle tank side plate 32 is erected from the periphery of the middle tank bottom plate 31 and has a cylindrical shape. The middle tank top 33 is installed on the upper end of the middle tank side plate 32 and has a dome shape.

[0020] The low-temperature steel used as the constituent material of the intermediate tank 3 is a metal material having the property that it is difficult to be embrittled at low temperatures even under extremely low temperatures. Austenitic stainless steel can be cited as the low-temperature steel. In addition, low-temperature steel such as nickel steel and aluminum alloy can also be used as the constituent material of the intermediate tank 3.

[0021] Between the outer tank bottom plate 21 and the middle tank bottom plate 31, there are disposed: a first level concrete layer 24 constituting the bottom of the outer cold insulation layer 12 and an outer bottom cold insulation layer 25. The first level concrete layer 24 is, for example, a leveled concrete layer made of concrete mixed with perlite and constructed on the outer tank bottom plate 21. The outer bottom cold insulation layer 25 is a layer arranged on the first level concrete layer 24 and having heat insulation properties. The outer bottom cold insulation layer 25 can be formed by an array of inorganic block materials having heat insulation properties, such as foam glass. For example, autoclaved lightweight concrete can also be laid on the outer bottom cold insulation layer 25.

[0022] The inner tank 4 is a closed body made of the same low-temperature steel as the intermediate tank 3, and includes an inner tank bottom plate 41, an inner tank side plate 42, and an inner tank top 43. The inner tank bottom plate 41 has a disc shape having a smaller diameter than the intermediate tank bottom plate 31. The inner tank side plate 42 is erected from the periphery of the inner tank bottom plate 41 and has a cylindrical shape. The inner tank top 43 is mounted on the upper end of the inner tank side plate 42 and has a dome shape. Liquefied hydrogen LH is stored inside the inner tank 4. In addition, the upper layer of the inner tank 4 forms a gas phase portion LA where hydrogen gas vaporized from the liquefied hydrogen LH accumulates.

[0023] Between the middle tank bottom plate 31 and the inner tank bottom plate 41, there are disposed: a second level concrete layer 34 constituting the bottom of the inner cold insulation layer 11 and an inner bottom cold insulation layer 35. The second level concrete layer 34 is made of, for example, concrete mixed with perlite, and is constructed on the middle tank bottom plate 31. The inner bottom cold insulation layer 35 is a layer arranged on the second level concrete layer 34 and having heat insulation properties. The inner bottom cold insulation layer 35 can be formed of, for example, foam glass blocks. For example, autoclaved lightweight concrete can also be laid on the inner bottom cold insulation layer 35.

[0024] Gaps of a specified width are formed between the inner tank 4 and the middle tank 3 and between the middle tank 3 and the outer tank 2, respectively, and are used as insulating spaces. The gap between the inner tank 4 and the middle tank 3 is used as an inner cold-keeping layer 11, and the gap between the middle tank 3 and the outer tank 2 is used as an outer cold-keeping layer 12. The inner cold-keeping layer 11 and the outer cold-keeping layer 12 are filled with powder insulation materials for improving cold-keeping properties. As the powder insulation material, for example, granular perlite can be used. In addition, in addition to the granular perlite, insulating materials such as glass wool can also be filled in the area between the side plates 22 and 32 and between the side plates 32 and 42 for surrounding the side periphery of the stored liquefied hydrogen LH. In this case, if the glass wool is installed on, for example, the outer side surface of the inner tank side plate 42 and / or the outer side surface of the middle tank side plate 32, the glass wool can protect the inner tank 4 and the middle tank 3 from the powder pressure of the perlite. The bottom of the inner cold insulation layer 11 is the second planar concrete layer 34 and the inner bottom cold insulation layer 35 , and the bottom of the outer cold insulation layer 12 is the first planar concrete layer 24 and the outer bottom cold insulation layer 25 .

[0025] The inner cold insulation layer 11 and the outer cold insulation layer 12 are filled with a designated sealing gas. As the sealing gas of the inner cold insulation layer 11, hydrogen and / or helium are preferably used. That is, it is preferred to use the same gas as the cryogenic liquefied gas stored in the inner tank 4 as the sealing gas. In addition, in the case of using hydrogen as the sealing gas, it is preferred that the pressure of the inner cold insulation layer 11 is set to be substantially the same as the gas phase pressure of the inner tank 4. If these requirements are met, the liquefaction or solidification of the sealing gas caused by the cold energy of the liquefied hydrogen LH stored in the inner tank 4 can be suppressed. In the outer cold insulation layer 12, an inert gas such as nitrogen having a boiling point higher than that of hydrogen is filled as the sealing gas. By filling the outer cold insulation layer 12 with a sealing gas, the invasion of air and / or moisture can be prevented.

[0026] In order to achieve the requirements for the sealing gas and pressure of the inner cold-insulating layer 11 described above, in this embodiment, a connecting pipe 44 is provided at the inner tank top 43. The connecting pipe 44 is a pipe body that connects the internal space of the inner tank 4 with the space of the inner cold-insulating layer 11. By providing the connecting pipe 44, the sealing gas can be supplied from the inner tank 4 to the inner cold-insulating layer 11. That is, there is a gas phase LA formed by hydrogen gas vaporized from liquefied hydrogen LH in the upper space of the inner tank 4, and the hydrogen gas in the gas phase LA can be introduced into the inner cold-insulating layer 11 as a sealing gas through the connecting pipe 44. In addition, since the inner cold-insulating layer 11 and the internal space of the inner tank 4 are in a connected state based on the connecting pipe 44, the pressure of the inner cold-insulating layer 11 and the gas phase pressure of the inner tank 4 can be made the same. In addition, instead of using the connecting pipe 44, a mechanism for independently adjusting the pressure of the inner cold-insulating layer 11 can be provided.

[0027] The gas phase pressure of the inner tank 4 is set to, for example, about 50 kPaG. In this case, it is preferred that the pressure of the inner cold-insulating layer 11 is also set to the same 50 kPaG, but it may be slightly different as long as it is within a range that is considered to be substantially the same as the gas phase pressure of the inner tank 4. That is, as long as it is within a range that does not reach a significant pressure difference that causes damage to the inner tank 4, the pressure of the inner cold-insulating layer 11 may be different from the gas phase pressure of the inner tank 4.

[0028] The pressure of the outer cold insulation layer 12 is set lower than the pressure of the inner cold insulation layer 11. The reason is that if the pressure of the outer cold insulation layer 12 is higher than the pressure of the inner cold insulation layer 11, there is a concern that the middle tank side plate 32 may be buckled due to the pressing force acting on the middle tank 3. The pressure of the outer cold insulation layer 12 can be set to, for example, about ±0.5 kPaG. By setting the pressure of the outer cold insulation layer 12 to such a value, there is also an advantage that air can be suppressed from entering the outer cold insulation layer 12.

[0029] The outer cold-insulating layer 12 is adjacent to the atmosphere via the wall surface of the outer tank 2, and is a closed space that is not connected to other spaces. Therefore, it is affected by the fluctuation of atmospheric pressure. For example, if the atmospheric pressure drops, the pressure of the outer cold-insulating layer 12 becomes relatively high. In view of this, in this embodiment, a pressure regulating tank 6 is provided to reduce the influence of the fluctuation of atmospheric pressure.

[0030] The pressure regulating tank 6 stores the sealing gas of the outer cold insulation layer 12, which is nitrogen in this embodiment. The pressure regulating tank 6 is connected to the outer cold insulation layer 12 through the pressure regulating pipe 61, and the sealing gas is allowed to enter and exit according to the pressure of the outer cold insulation layer 12, thereby adjusting the pressure of the outer cold insulation layer 12. Specifically, the sealing gas in the outer cold insulation layer 12 is received by the pressure regulating tank 6 through the pressure regulating pipe 61 when the pressure of the outer cold insulation layer 12 increases, and returns from the pressure regulating tank 6 to the outer cold insulation layer 12 when the pressure decreases.

[0031] In order to prevent the inner tank side plate 42 and the middle tank side plate 32 from hanging, the three-layer shell tank 1 is provided with an inner tank anchor band 51 and a middle tank anchor band 52. The upper end 51A of the inner tank anchor band 51 is connected to the inner tank side plate 42, and the lower end 51B thereof is connected to the middle tank side plate 32 and the middle tank bottom plate 31 via a bracket 53. The side end edge of the bracket 53 is welded near the lower end of the middle tank side plate 32, and the lower end edge of the bracket 53 is welded near the outer peripheral edge of the middle tank bottom plate 31. The upper end 52A of the middle tank anchor band 52 is connected to the middle tank side plate 32, and the lower end 52B thereof is fixed to the tank foundation 10. The lower end 52B is fixed to the tank foundation 10 via an anchor box 54 embedded in the tank foundation 10. The anchor bands 51 and 52 are arranged in a circumferential direction at a predetermined interval. By providing the anchor bands 51 and 52 , it is possible to prevent the middle channel side plate 32 and the inner channel side plate 42 from being suspended, thereby improving the earthquake resistance.

[0032] According to the triple-shell tank 1 involved in the first embodiment described above, since the middle tank 3 is formed of low-temperature steel, the middle tank 3 has excellent resistance to low-temperature embrittlement. Therefore, even if the insulation thickness of the inner tank 4, that is, the thickness of the inner cold-keeping layer 11, is reduced, it is difficult for the middle tank 3 to become low-temperature embrittled. If the gap between the middle tank side plate 32 and the inner tank side plate 42 is set to be shorter, the middle tank side plate 32 is easily affected by the cold energy of the liquefied hydrogen LH stored in the inner tank 4. However, if the middle tank side plate 32 is made of low-temperature steel, it is difficult to become low-temperature embrittled even if it is affected by cold energy. Therefore, the inner cold-keeping layer 11 can be set to a narrow thickness, and the outer diameter of the tank body 1T can be compacted. As a result, the land area required for the construction of the triple-shell tank 1 can be reduced.

[0033] In addition, since hydrogen is filled in the inner cold-insulating layer 11 as a sealing gas, it is difficult for the sealing gas to condense. In particular, since the internal space of the inner tank 4 is connected to the inner cold-insulating layer 11 by the connecting pipe 44, the hydrogen present in the gas phase LA of the inner tank 4 can be used, which has the advantage of not requiring a separate hydrogen supply system. Moreover, the pressure of the inner cold-insulating layer 11 and the pressure of the gas phase LA can be set to be equal without providing a special pressure adjustment unit. In addition, since the pressure of the outer cold-insulating layer 12 is set to be lower than the pressure of the inner cold-insulating layer 11, and the pressure regulating tank 6 is provided as a pressure buffer, the buckling of the intermediate tank 3 can be suppressed.

[0034] [Second embodiment]

[0035] Figure 2 2 is a cross-sectional view showing a main part of a three-layer shell tank 1A according to the second embodiment. In the second embodiment, a three-layer shell tank 1A is illustrated in which a reinforcement structure is provided in a portion receiving a load from the middle tank side plate 32 and the inner tank side plate 42. Figure 2 Omitted Figure 1 The three-layer shell tank 1A has a reinforcement structure in the middle tank bottom plate 31 forming the bottom surface of the middle tank 3 and the inner tank bottom plate 41 forming the bottom surface of the inner tank 4, and also has a reinforcement structure in the outer bottom cold insulation layer 25 and the inner bottom cold insulation layer 35. This reinforcement structure can also be applied to the tanks of the first embodiment described above and the second to fifth embodiments described later.

[0036] The middle tank bottom plate 31 is formed of low temperature steel, and includes: a middle tank annular portion 311 constituting an annular portion near the outer periphery of the middle tank bottom plate 31; and a bottom plate general portion 312 on the inner side of the middle tank annular portion 311. Similarly, the inner tank bottom plate 41 includes: an inner tank annular portion 411 constituting an annular portion near the outer periphery of the inner tank bottom plate 41; and a bottom plate general portion 412 on the inner side of the inner tank annular portion 411. The middle tank annular portion 311 is formed to be thicker than the bottom plate general portion 312. The middle tank side plate 32 is erected on the middle tank annular portion 311. The middle tank side plate 32 is assembled by stacking a plurality of annular layers formed by arranging a plurality of side plate members in a circular ring shape. When constructing the middle tank side plate 32, a guide rail for conveying the side plate members is laid on the outer tank top 23.

[0037] The inner groove annular portion 411 is also formed to be thicker than the bottom plate general portion 412. The inner groove side plate 42 is vertically arranged on the inner groove annular portion 411. The inner groove side plate 42 is also assembled by stacking multiple layers of annular layers formed by arranging multiple side plate members in a circular ring shape. Figure 2 Although not shown in the figure, an outer groove annular portion with increased thickness may be provided near the outer periphery of the outer groove bottom plate 21 .

[0038] The outer bottom cold insulation layer 25 constituting the bottom surface portion of the outer cold insulation layer 12 is provided with a first ring portion 26 near its radial outer periphery. The first ring portion 26 is arranged in an annular shape below the middle groove annular portion 311, and is a high-strength concrete layer such as a perlite concrete block. A concrete layer 27 (solid cold insulation material with high strength) is arranged at a portion of the first ring portion 26 that directly bears the load of the middle groove side plate 32, and the concrete layer 27 has a higher strength than the general portion of the outer bottom cold insulation layer 25 located inside the middle groove side plate 32 and the main portion of the first ring portion 26.

[0039] The inner bottom cold insulation layer 35 constituting the bottom surface portion of the inner cold insulation layer 11 is provided with a second ring portion 36 near its radial outer periphery. The second ring portion 36 is arranged in an annular shape within the width of the first ring portion 26 and below the inner groove annular portion 411. The second ring portion 36 can also be constructed of concrete such as a perlite concrete block. A concrete layer 37 is arranged at a portion of the second ring portion 36 that directly bears the load of the inner groove side plate 42, and the concrete layer 37 has a higher strength than the general portion of the inner bottom cold insulation layer 35 located inside the inner groove side plate 42 and the main portion of the second ring portion 36.

[0040] According to the triple shell tank 1A involved in the second embodiment, the strength of the lower peripheral edge of the middle tank 3 can be improved based on the increased thickness of the middle tank annular portion 311. Similarly, the strength of the lower peripheral edge of the inner tank 4 can be improved based on the increased thickness of the inner tank annular portion 411. In addition, since the reinforced concrete layer 27 is arranged at the part directly bearing the load of the middle tank side plate 32, it can be a structure that is difficult for the tank to sink even if the tank's own weight or earthquake load is applied.

[0041] [Third embodiment]

[0042] Figure 3 1 is a cross-sectional view showing a triple shell tank 1B according to the third embodiment. In the third embodiment, a triple shell tank 1B having a protective structure for a tank body 1T is exemplified. The triple shell tank 1B has a reinforcement member 38 having a rib-shaped member protruding from the middle tank side plate 32, and a safety valve 7 for limiting the increase in the internal pressure of the middle tank 3. Figure 1 The parts with the same reference numerals as previously described Figure 1 Since what has been described is the same, its description is omitted here (the same applies to the 4th and 5th embodiments described later).

[0043] The reinforcement member 38 is a member with a T-shaped cross section formed by a joint body of a transverse plate 381 and a longitudinal plate 382, ​​both of which are made of flat steel plates. The transverse plate 381 protrudes in a substantially horizontal direction from the outer peripheral surface of the middle groove side plate 32 to the radial outer side of the middle groove 3. The transverse plate 381 is fixed to the outer peripheral surface of the middle groove side plate 32 by welding over the entire circumference of the outer peripheral surface. The longitudinal plate 382 is fixed to the protruding end of the transverse plate 381 by welding. The joint body of the transverse plate 381 and the longitudinal plate 382 forms an annular reinforcement rib that annularly surrounds the outer peripheral surface of the middle groove side plate 32. Multiple layers of the annular reinforcement rib are arranged in the up-down direction on the outer peripheral surface of the middle groove side plate 32.

[0044] The safety valve 7 is attached to the lead-out pipe 71 led out from the middle tank 3. The base end of the lead-out pipe 71 opens in the interlayer between the middle tank top 33 and the inner tank top 43, that is, in the inner cold insulation layer 11, and the distal end protrudes from the tank body 1T to the outside. The safety valve 7 is a valve that becomes open when the pressure in the inner cold insulation layer 11 exceeds a predetermined threshold.

[0045] According to the three-layer shell tank 1B involved in the third embodiment, the strength of the middle tank side plate 32 can be improved by the reinforcement member 38. That is, by welding the rib-shaped reinforcement member 38 to the outer peripheral surface of the middle tank side plate 32, the rigidity can be improved compared with the middle tank side plate 32 of a simple cylindrical structure. Therefore, even if the side pressure increases due to the cold insulation material of the outer cold insulation layer 12, the buckling of the middle tank side plate 32 can be suppressed. In addition, Figure 3The T-shaped reinforcement member 38 shown is an example, and the reinforcement member 38 may be any rib-shaped member as long as it can increase the rigidity of the middle channel side plate 32 .

[0046] In addition, since the triple shell tank 1B is provided with the safety valve 7, when the pressure in the intermediate tank 3 reaches a high pressure exceeding a specified value, the pressure can be released by the safety valve 7. In particular, in the present embodiment, since the internal space of the inner tank 4 and the inner cold insulation layer 11 are connected through the connecting pipe 44, the operation of the safety valve 7 can also suppress the pressure rise of the inner tank 4. Thus, the maintainability of the tank body 1T is improved. In addition, at least one of the reinforcement 38 and the safety valve 7 can also be applied to the triple shell tank 1 of the first embodiment.

[0047] In the third embodiment, various modified embodiments can be adopted. Figure 3 In the figure, an example in which the cross-sectional shape of the reinforcement member 38 is T-shaped is shown, but the cross-sectional shape of the reinforcement member 38 may also be I-shaped, L-shaped, or H-shaped. Figure 3 , an example is shown in which the reinforcing plate 38 is protruded radially outwardly of the middle tank side plate 32, but the reinforcing plate 38 may also be installed radially inwardly of the middle tank side plate 32. In addition, the fixing method of the transverse plate 381 of the reinforcing member 38 and the middle tank side plate 32 and the fixing method of the transverse plate 381 and the longitudinal plate 382 may also be performed by methods other than welding.

[0048] [Fourth embodiment]

[0049] Figure 4 1 is a cross-sectional view showing a triple shell tank 1C according to the fourth embodiment. In the fourth embodiment, a triple shell tank 1C is exemplified in which a thermal reinforcement member 8 is arranged inside the outer tank 2. It is necessary to assume that the inner tank 4 storing the liquefied hydrogen LH and the intermediate tank 3 surrounding the inner tank 4 are damaged, thereby causing the liquefied hydrogen LH to leak out. The thermal reinforcement member 8 is arranged to improve the cold resistance of the outer tank side plate 22 and the outer tank bottom plate 21 so that the outer tank side plate 22 and the outer tank bottom plate 21 are not damaged due to low-temperature embrittlement even if the liquefied hydrogen LH leaks out.

[0050] The heat reinforcement member 8 is formed of, for example, the same low-temperature steel as the intermediate tank 3, and has a side portion 81 and a bottom portion 82. The side portion 81 extends upward from the lowest portion at a predetermined height on the inner side of the outer tank side plate 22. The height of the side portion 81 is set with reference to the maximum storage amount of liquefied hydrogen LH, the volume of the inner cold insulation layer 11 and the outer cold insulation layer 12, etc. The bottom portion 82 is arranged on the inner side near the outer periphery of the outer tank bottom plate 21. Figure 4, an example is shown in which the bottom portion 82 is arranged so as to fill the gap between the outer peripheral edge of the first plane concrete layer 24 and the outer channel side plate 22 .

[0051] As the heat reinforcement member 8, a heat insulating material may be used instead of low temperature steel. In this case, for example, the side portion 81 may be formed of hard polyurethane foam, and the bottom portion 82 may be formed of perlite flat concrete. In addition, a form may be adopted in which the heat insulating material formed on the inner side of the outer tank bottom plate 21 and the outer tank side plate 22 is covered with low temperature steel. In addition, the heat insulating material may be attached to the inner side of the outer tank top 23.

[0052] According to the triple shell tank 1C according to the fourth embodiment, even if a situation such as leakage of liquefied hydrogen LH from the inner tank 4 and the intermediate tank 3 occurs, the liquefied hydrogen LH comes into contact with the heat reinforcement member 8 disposed on the inner side of the outer tank side plate 22. Therefore, damage due to low-temperature embrittlement of the outer tank 2 can be prevented, and outflow of the liquefied hydrogen LH to the outside of the tank body 1T can be suppressed.

[0053] [Fifth embodiment]

[0054] Figure 5 1 is a cross-sectional view showing a triple shell tank 1D according to a fifth embodiment. In the fifth embodiment, a triple shell tank 1D is shown with attention paid to the relationship between the thickness of the inner cold insulation layer 11 and the thickness of the outer cold insulation layer 12. The inner cold insulation layer 11 has a thickness d1 in the radial direction of the tank body 1T. The outer cold insulation layer 12 has a thickness d2 in the radial direction that is greater than the thickness d1.

[0055] As described above, the sealing gas is sealed in the outer cold insulation layer 12. The thickness d1 is set to a thickness that can ensure an insulating space that allows the temperature of the outer peripheral surface of the middle tank side plate 32 to be higher than the condensation temperature of the sealing gas. When the sealing gas is nitrogen, the thickness d1 is selected to set the temperature of the outer peripheral surface of the middle tank side plate 32 to be higher than -196°C, which is the boiling point of nitrogen. Even if exposed to such an extremely low temperature, since the middle tank 3 is formed of low-temperature steel, low-temperature embrittlement does not occur. In other words, since the middle tank 3 is a structure of low-temperature steel, the thickness d1 can be set to a smaller thickness. The thickness d2 of the outer cold insulation layer 12 is set to a thickness that can limit the amount of heat input from the outer tank side plate 22 at room temperature to the middle tank side plate 32. The ratio of the thickness d1 of the inner cold insulation layer 11 to the thickness d2 of the outer cold insulation layer 12 can be set, for example, in the range of 1:1.5 to 5, preferably in the range of 1:1.8 to 3.5.

[0056] Since the thickness d1 of the inner cold insulation layer 11 can be set small, it is easy to realize the compactness of the tank body 1T accordingly. When the intermediate tank 3 is not formed of low-temperature steel, a corresponding thickness d10 is required to prevent low-temperature embrittlement of the intermediate tank side plate 32. As a result, the outer diameter of the tank body 1T increases. Figure 5 The dotted lines shown schematically show the positions of the outer tank side plate 22A and the middle tank side plate 32A when low-temperature steel is not used. The thickness d10 between the inner tank side plate 42 and the middle tank side plate 32A must be set to be considerably larger than the thickness d1 of the present embodiment. In addition, although the thickness d20 between the middle tank side plate 32A and the outer tank side plate 22A is somewhat larger than the thickness d2 of the outer cold insulation layer 12 of the present embodiment, when compared with the sum of the thickness d10 and the thickness d20, it is considerably larger than the sum of the thickness d1 and the thickness d2 of the present embodiment. In the present embodiment, since the thickness d1 can be set to a smaller thickness, the outer diameter of the tank body 1T can be reduced by the thickness d3 relative to the outer tank side plate 22A. In addition, the outer diameter of the middle tank 3 can be suppressed, and there is an advantage that the amount of steel used can be reduced compared to the case where low-temperature steel is not used. Moreover, since the thickness d2 can be set to a relatively large size, the thermal insulation of the outer cold insulation layer 12 can be improved. In this case, if a member having excellent heat insulation properties is sealed in the outer cold-retaining layer 12 , the thickness d2 can be set to a small dimension, and this can also contribute to the compactness of the tank body 1T.

[0057] On the bottom side of the tank body 1T, the second plane concrete layer 34 and the inner bottom cold insulation layer 35 constitute the bottom of the inner cold insulation layer 11, and the sum of these constitutes a thickness d4. The first plane concrete layer 24 and the outer bottom cold insulation layer 25 constitute the bottom of the outer cold insulation layer 12, and the sum of these constitutes a thickness d5. The thickness d5 of the outer bottom cold insulation layer 25 is set to be larger than the thickness d4 of the inner bottom cold insulation layer 35. As a result of the intermediate tank bottom plate 31 also being formed of low-temperature steel, the thickness d4 can be set to be relatively small, and as a result, the thickness d5 becomes relatively large. As a result, the thermal insulation of the outer cold insulation layer 12 can be effectively improved.

[0058] [Other embodiments]

[0059] As mentioned above, although various embodiments of the present disclosure have been described, the present disclosure is not limited to the above-mentioned embodiments, and the following embodiments can be adopted, for example.

[0060] (1) In the above embodiment, the side plates 32, 42 of the middle tank 3 and the inner tank 4 are exemplified as being integral with the tank tops 33, 43 in a dome-shaped tank top. The inner tank top 43 may also be constructed in a suspended ceiling manner. When the inner tank top 43 is constructed in a suspended ceiling manner, the inner tank top 43 is supported by a hanging member hanging from the middle tank top 33. A sealing material is attached to the joint portion between the inner tank side plate 42 and the inner tank top 43.

[0061] (2) In the above embodiment, a pipe body that simply penetrates the inner tank top 43 is exemplified as the connecting pipe 44 that connects the inner space of the inner tank 4 with the inner cold insulation layer 11. In order to improve maintainability, the connecting pipe 44 may be provided with a path that partially passes through the outside of the tank body 1T.

[0062] (3) In the above-mentioned embodiment, the three-layer shell tanks 1, 1A to 1D of the ground-mounted type are exemplified as the cryogenic liquefied gas storage tank. The cryogenic liquefied gas storage tank is not limited to the ground-mounted type, and may be a recessed type or the like in which a part of the tank is embedded in the ground.

[0063] [Summary of the present disclosure]

[0064] A low-temperature liquefied gas storage tank involved in one aspect of the present disclosure is a tank of a flat-bottom cylindrical three-layer shell structure, which includes: an inner tank for storing low-temperature liquefied gas; an intermediate tank, the inner tank is surrounded by an inner cold insulation layer; and an outer tank, the intermediate tank is surrounded by an outer cold insulation layer; wherein the intermediate tank is formed of low-temperature steel.

[0065] According to the low-temperature liquefied gas storage tank, since the intermediate tank is formed of low-temperature steel, it has excellent resistance to low-temperature embrittlement. Therefore, even if the thickness of the inner cold insulation layer is reduced, the low-temperature embrittlement of the intermediate tank will not occur. Therefore, the land area required for the construction of the low-temperature liquefied gas storage tank can be reduced.

[0066] In the above-mentioned cryogenic liquefied gas storage tank, the inner cold-insulating layer may contain a sealing gas containing the same gas as the cryogenic liquefied gas stored in the inner tank.

[0067] According to this technical solution, the sealed gas is difficult to be liquefied or solidified due to the cold energy of the liquefied gas stored in the inner tank. In addition, since the raw material of the sealed gas exists in the inner tank, it is easy to obtain the sealed gas.

[0068] In the above-mentioned low-temperature liquefied gas storage tank, it is preferred that the pressure of the inner cold insulation layer is set to be substantially the same as the gas phase pressure of the inner tank.

[0069] According to this technical solution, condensation of the sealing gas contained in the inner cold-insulating layer can be suppressed. In addition, "substantially the same" means that if the pressure of the inner cold-insulating layer and the gas phase pressure of the inner tank are within a range that does not reach a significant pressure difference that causes damage to the inner tank, even if there is a difference between the pressure of the inner cold-insulating layer and the gas phase pressure of the inner tank, it is allowed.

[0070] The above-mentioned low-temperature liquefied gas storage tank may further include: a connecting pipe to connect the internal space of the inner tank with the inner cold insulation layer.

[0071] According to this technical solution, the sealing gas can be always supplied to the inner cold-insulating layer from the gas phase part of the inner tank. In addition, the pressure of the inner cold-insulating layer and the gas phase pressure of the inner tank can be set to be substantially the same without using a special pressure adjustment unit.

[0072] In the above-mentioned cryogenic liquefied gas storage tank, the following technical solution may be adopted: the outer cold insulation layer contains a sealing gas containing an inert gas, and the pressure of the outer cold insulation layer is lower than the pressure of the inner cold insulation layer.

[0073] According to this technical solution, the moisture-proofing of the outer cold-keeping layer can be achieved by sealing the gas. In addition, since the pressure of the outer cold-keeping layer is set to be lower than the pressure of the inner cold-keeping layer, it is easy to suppress the entry of air to the outer cold-keeping layer 12.

[0074] The above-mentioned low-temperature liquefied gas storage tank may also include: a pressure regulating tank connected to the outer cold insulation layer to store the inert gas; wherein the pressure regulating tank can allow the inert gas to enter and exit according to the pressure fluctuation of the outer cold insulation layer, thereby adjusting the pressure of the outer cold insulation layer.

[0075] According to this aspect, since the pressure of the outer cold-insulating layer can be adjusted according to the fluctuation of the atmospheric pressure, the influence of the fluctuation of the atmospheric pressure can be reduced.

[0076] In the above-mentioned low-temperature liquefied gas storage tank, the following technical solution can be adopted: the intermediate groove includes an intermediate groove bottom plate forming the bottom surface of the intermediate groove, and the intermediate groove bottom plate has: an intermediate groove annular portion constituting an annular portion near the outer periphery of the intermediate groove bottom plate; and a bottom plate general portion on the inner side of the intermediate groove annular portion, wherein the thickness of the intermediate groove annular portion is greater than the thickness of the bottom plate general portion.

[0077] According to this technical solution, the strength of the middle groove near the lower end peripheral edge can be improved by the middle groove annular portion having a larger thickness.

[0078] In the above-mentioned low-temperature liquefied gas storage tank recorded, the following technical solution can be adopted: the intermediate tank includes an intermediate tank side plate forming the side of the intermediate tank, the outer cold insulation layer includes an outer bottom cold insulation layer constituting the bottom surface portion of the outer cold insulation layer, and the outer bottom cold insulation layer includes a solid cold insulation material with higher strength than the general part of the outer bottom cold insulation layer located on the inner side relative to the intermediate tank side plate at the position bearing the load of the intermediate tank side plate.

[0079] According to this aspect, since the portion of the outer cold insulation layer that receives the load of the intermediate tank side plate includes a high-strength solid cold insulation material, the tank can be made into a structure that is unlikely to sink even when subjected to loads such as the tank's own weight or an earthquake.

[0080] In the above-mentioned cryogenic liquefied gas storage tank, the intermediate tank may include: an intermediate tank side plate forming a side surface of the intermediate tank; and a reinforcing member having a rib-shaped member protruding from the intermediate tank side plate.

[0081] According to this technical solution, the strength of the middle channel side plate can be improved by the reinforcement member, so that the buckling of the middle channel side plate can be suppressed.

[0082] The above-mentioned cryogenic liquefied gas storage tank may further include: a safety valve to limit the increase in the internal pressure of the intermediate tank.

[0083] According to this technical solution, when the pressure in the intermediate tank reaches a high pressure exceeding a predetermined value, the pressure can be released by the safety valve.

[0084] The cryogenic liquefied gas storage tank may further include a heat reinforcement member disposed at least on the inner side of the bottom and the side of the outer tank.

[0085] According to this aspect, even if the cryogenic liquefied gas should leak out of the inner tank, since the heat reinforcement member is provided inside the outer tank, damage due to low-temperature embrittlement of the outer tank can be prevented.

[0086] In the above-mentioned cryogenic liquefied gas storage tank, the outer cold insulation layer may contain a sealing gas containing an inert gas, and the thickness of the outer cold insulation layer may be set to be greater than the thickness of the inner cold insulation layer. In this case, the ratio of the thickness of the inner cold insulation layer to the thickness of the outer cold insulation layer may be set in the range of 1:1.5 to 5. Preferably, it is set in the range of 1:1.8 to 3.5.

[0087] According to this technical solution, the thermal insulation of the outer cold insulation layer can be improved. As a result, the thickness of the inner cold insulation layer can be set relatively narrow, and the tank as a whole can be easily made compact. In addition, by using low-temperature steel in the middle tank, the outer diameter of the middle tank can be suppressed, which has the advantage of reducing the amount of steel used compared to the case where low-temperature steel is not used.

[0088] In the above-mentioned low-temperature liquefied gas storage tank, the following technical solution can be adopted: the outer cold insulation layer includes an outer bottom cold insulation layer arranged between the bottom plate of the outer tank and the bottom plate of the middle tank, the inner cold insulation layer includes an inner bottom cold insulation layer arranged between the bottom plate of the middle tank and the bottom plate of the inner tank, and the thickness of the outer bottom cold insulation layer is greater than the thickness of the inner bottom cold insulation layer.

[0089] According to this technical solution, by using low-temperature steel in the middle tank, the inner bottom cold insulation layer can be set thinner, and the height dimension of the tank can be made compact. As a result, the thickness of the outer bottom cold insulation layer becomes greater than that of the inner bottom cold insulation layer, and the heat insulation effect of the outer bottom cold insulation layer can be improved.

Claims

1. A cryogenic liquefied gas storage tank, characterized in that A tank of a flat-bottom cylindrical three-layer shell structure, comprising: Inner tank, storing cryogenic liquefied gas; an intermediate tank, the inner tank being surrounded by an inner cold-insulating layer; and The outer tank surrounds the middle tank through an outer cold insulation layer; wherein, The intermediate tank is formed of low-temperature steel.

2. The cryogenic liquefied gas storage tank according to claim 1, characterized in that: The inner cold-insulating layer includes a sealing gas containing the same gas as the cryogenic liquefied gas stored in the inner tank.

3. The cryogenic liquefied gas storage tank according to claim 2, characterized in that: The pressure of the inner cold-insulating layer is set to be substantially the same as the gas phase pressure of the inner tank.

4. The cryogenic liquefied gas storage tank according to claim 3, characterized in that Also includes: A connecting pipe connects the inner space of the inner tank with the inner cold-insulating layer.

5. The cryogenic liquefied gas storage tank according to any one of claims 1 to 4, characterized in that: The outer cold-insulating layer contains a sealing gas containing an inert gas, The pressure of the outer cold-insulating layer is lower than the pressure of the inner cold-insulating layer.

6. The cryogenic liquefied gas storage tank according to claim 5, characterized in that Also includes: A pressure regulating tank is connected to the outer cold insulation layer and stores the inert gas; wherein: The pressure regulating tank allows the inert gas to flow in and out according to the pressure fluctuation of the outer cold insulation layer, thereby adjusting the pressure of the outer cold insulation layer.

7. The cryogenic liquefied gas storage tank according to any one of claims 1 to 6, characterized in that: The intermediate groove comprises an intermediate groove bottom plate forming the bottom surface of the intermediate groove, The intermediate groove bottom plate comprises: an intermediate groove annular portion constituting an annular portion near the outer periphery of the intermediate groove bottom plate; and a bottom plate general portion inside the intermediate groove annular portion, wherein: The thickness of the annular portion of the intermediate groove is greater than the thickness of the general portion of the bottom plate.

8. The cryogenic liquefied gas storage tank according to any one of claims 1 to 6, characterized in that: The intermediate groove comprises an intermediate groove side plate forming a side surface of the intermediate groove, The outer cold-insulating layer includes an outer bottom cold-insulating layer constituting the bottom surface portion of the outer cold-insulating layer. The outer bottom cold insulation layer includes a solid cold insulation material having a higher strength than a general portion of the outer bottom cold insulation layer located inside the middle groove side plate at a portion receiving a load of the middle groove side plate.

9. The cryogenic liquefied gas storage tank according to any one of claims 1 to 6, characterized in that: The middle trough includes: a middle trough side plate forming a side surface of the middle trough; and a reinforcement member having a rib-shaped member protruding from the middle trough side plate.

10. The cryogenic liquefied gas storage tank according to any one of claims 1 to 9, characterized in that Also includes: The safety valve limits the increase in the internal pressure of the intermediate tank.

11. The cryogenic liquefied gas storage tank according to any one of claims 1 to 10, characterized in that Also includes: The heat reinforcement member is arranged at least inside the bottom and side portions of the outer tank.

12. The cryogenic liquefied gas storage tank according to any one of claims 1 to 11, characterized in that: The outer cold-insulating layer contains a sealing gas containing an inert gas, The thickness of the outer cold-insulating layer is greater than the thickness of the inner cold-insulating layer.

13. The cryogenic liquefied gas storage tank according to claim 12, characterized in that: The ratio of the thickness of the inner cold-insulating layer to the thickness of the outer cold-insulating layer is set in the range of 1:1.5 to 5.

14. The cryogenic liquefied gas storage tank according to any one of claims 1 to 11, characterized in that: The outer cold-insulating layer includes an outer bottom cold-insulating layer disposed between the bottom plate of the outer tank and the bottom plate of the middle tank. The inner cold-insulating layer includes an inner bottom cold-insulating layer disposed between the bottom plate of the middle tank and the bottom plate of the inner tank. The thickness of the outer bottom cold insulation layer is greater than the thickness of the inner bottom cold insulation layer.

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