Construction method for triple-walled tanks

Abstract

To shorten a construction period for constructing a triple-shell tank with inner, intermediate and outer tanks.SOLUTION: A roof connection body 20 is formed by temporarily securing an intermediate tank roof 33 on top of an inner tank roof 43 with intermediate tank roof supports 61, and then temporarily securing an outer tank roof 23 on top of the intermediate tank roof 33 with outer tank roof central supports 62 and outer tank roof peripheral supports 63. An outer tank side panel 22 of a predetermined height is constructed around the roof connection body 20. Then, a seal is applied between an outer edge 23E of the outer tank roof 23 and the inner surface of the outer tank side plate 22 to form a sealed space, and air is supplied to the sealed space with a blower 7 to air-raise the roof connection body 20. Thereafter, the outer edge 23E of the outer tank roof 23 and the upper edge of the outer tank side plate 22 are fixed. Then, an inner tank side plate 42 and intermediate tank side plate 32 are constructed, and the aforementioned temporary fixing of the roof connection body 20 is released to fix the inner tank roof 43 to the inner tank side plate 42, and the intermediate tank roof 33 to the intermediate tank side plate 32.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a construction method for a triple-shell tank for storing cryogenic liquefied gas.

Background Art

[0002] As a facility for storing cryogenic liquefied gas, a flat-bottom tank having a multi-shell structure is known. The construction of this type of multi-shell tank generally requires a long construction period because the building itself is large-scale and the provision of a heat insulation structure is required. For example, Patent Documents 1 and 2 disclose construction methods for tanks having a double-shell structure including an inner tank and an outer tank for the purpose of shortening the construction period. In recent years, a flat-bottom tank having a triple-shell structure with an intermediate tank between the inner tank and the outer tank has been considered as a storage facility for extremely low-temperature liquefied gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the structure of a triple-shell tank is naturally more complex than that of a double-shell tank, the construction period thereof tends to be longer.

[0005] An object of the present disclosure is to provide a construction method capable of shortening the construction period in constructing a triple-shell tank including an inner tank, an intermediate tank, and an outer tank.

Means for Solving the Problems

[0006] A construction method for a triple-walled tank according to one aspect of the present disclosure is a construction method for a triple-walled tank comprising an inner tank, an intermediate tank, and an outer tank, each having a roof and side plates, wherein the intermediate tank roof is temporarily fixed on the inner tank roof, and the outer tank roof is further temporarily fixed on the intermediate tank roof to form a roof assembly, an outer tank side plate of a predetermined height is constructed around the roof assembly, a sealing treatment is applied between the outer edge of the outer tank roof and the inner surface of the outer tank side plate to form a sealed space, and air is supplied to the sealed space to air-race the roof assembly, fixing the outer tank roof and the outer tank side plate, constructing the inner tank side plate and the intermediate tank side plate, the temporary fixing of the roof assembly is released, and the inner tank roof and the inner tank side plate are fixed, and the intermediate tank roof and the intermediate tank side plate are fixed. [Effects of the Invention]

[0007] According to this disclosure, a construction method is available that can shorten the construction period for building a triple-hull tank comprising an inner tank, an intermediate tank, and an outer tank. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a longitudinal cross-sectional view showing the structure of a triple-walled tank that is the subject of construction in this disclosure. [Figure 2] Figure 2 is a process chart of the construction method for the triple-walled tank according to this disclosure. [Figure 3] Figure 3 is a diagram showing one step in the construction method of the triple-walled tank, with a cross-section of half of the tank. [Figure 4] Figure 4 shows one step in the construction method of the triple-walled tank. [Figure 5] Figure 5 shows one step in the construction method of the triple-walled tank. [Figure 6] Figure 6 shows one step in the construction method of the triple-walled tank. [Figure 7] Figure 7 shows one step in the construction method of the triple-walled tank. [Figure 8] Figure 8 shows one step in the construction method of the triple-walled tank. [Figure 9] Figure 9 shows one step in the construction method of the triple-walled tank. [Figure 10] Figure 10 shows one step in the construction method of the triple-walled tank. [Figure 11] Figure 11 shows one step in the construction method of the triple-walled tank. [Figure 12] Figure 12 shows one step in the construction method of the triple-walled tank. [Figure 13] Figure 13 shows one step in the construction method of the triple-walled tank. [Figure 14] Figure 14 shows one step in the construction method of the triple-walled tank. [Figure 15] Figure 15 shows one step in the construction method of the triple-walled tank. [Figure 16] Figure 16 shows one step in the construction method of the triple-walled tank. [Modes for carrying out the invention]

[0009] Hereinafter, with reference to the drawings, embodiments of the construction method for the triple-walled tank according to this disclosure will be described in detail. The triple-walled tank that is the subject of construction according to this disclosure is a tank for storing low-temperature liquefied gas, and is a flat-bottomed tank with a triple-walled structure that is installed on the ground. The liquefied gas to be stored is, for example, liquefied hydrogen or liquid helium.

[0010] [Structure of a triple-hulled tank] First, the structure of the triple-shell tank 1, which is the subject of construction in this disclosure, will be explained based on the longitudinal cross-sectional view shown in Figure 1. Figure 1 illustrates a triple-shell tank 1 for storing liquid hydrogen LH. The triple-shell tank 1 includes a tank foundation 10, an outer tank 2 erected on the tank foundation 10, an intermediate tank 3 enclosed within the outer tank 2, and an inner tank 4 enclosed within the intermediate tank 3. The outer tank 2, intermediate tank 3, and inner tank 4 all have a circular shape when viewed from above and are arranged concentrically.

[0011] The tank foundation 10 is a concrete layer that constitutes 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 outer tank 2 is a sealed 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 roof 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 stands upright from the periphery of the outer tank bottom plate 21 and has a cylindrical shape. The outer tank roof 23 is attached to the upper end of the cylindrical outer tank side plate 22 so as to close the upper opening of the outer tank side plate 22 and has a dome shape.

[0012] The intermediate tank 3 is a sealed body made of metal such as SUS and is arranged inside the outer tank 2. The intermediate tank 3 includes an intermediate tank bottom plate 31, an intermediate tank side plate 32, and an intermediate tank roof 33. The intermediate tank bottom plate 31 has a disc shape with a smaller diameter than the outer tank bottom plate 21. The intermediate tank side plate 32 stands upright from the periphery of the intermediate tank bottom plate 31 and has a cylindrical shape. The intermediate tank roof 33 is attached to the upper end of the intermediate tank side plate 32 and has a dome shape.

[0013] Between the outer tank bottom plate 21 and the intermediate tank bottom plate 31, a first-level concrete layer 24, a first ring portion 25, and an outer bottom insulation layer 26 are interposed. The first-level concrete layer 24 is a concrete layer for leveling constructed on the outer tank bottom plate 21. The first ring portion 25 is a high-strength concrete layer arranged in a ring shape near the periphery of the first-level concrete layer 24. A reinforced concrete layer 251 is arranged at the location where the intermediate tank side plate 32 directly receives the load in the first ring portion 25. The outer bottom insulation layer 26 is a layer having heat insulation properties, which is arranged above the first-level concrete layer 24 and inside the first ring portion 25. The first ring portion 25 can be formed by an array of heat-insulating concrete blocks such as perlite concrete blocks. The outer bottom insulation layer 26 can be formed by an array of heat-insulating inorganic block materials such as foamed glass. A plate material of lightweight cellular concrete, for example, may be laid on the outer bottom insulation layer 26.

[0014] The inner tank 4 is the tank that actually stores the liquid, and is a sealed body made of metal such as SUS, and is located inside the intermediate tank 3. The inner tank 4 includes an inner tank bottom plate 41, inner tank side plates 42, and inner tank roof 43. The inner tank bottom plate 41 has a disc shape with a smaller diameter than the intermediate tank bottom plate 31. The inner tank side plates 42 are erected from the periphery of the inner tank bottom plate 41 and have a cylindrical shape. The inner tank roof 43 is attached to the upper end of the inner tank side plates 42 and has a dome shape. Liquid hydrogen LH is stored inside the inner tank 4.

[0015] Between the intermediate tank bottom plate 31 and the inner tank bottom plate 41, a second level concrete layer 34, a second ring section 35, and an inner bottom insulation layer 36 are interposed. The second level concrete layer 34 is constructed on top of the intermediate tank bottom plate 31. The second ring section 35 is a high-strength concrete layer arranged in a ring shape near the periphery of the second level concrete layer 34. A reinforced concrete layer 351 is placed in the area of ​​the second ring section 35 that directly receives the load of the inner tank side plate 42. The inner bottom insulation layer 36 is an insulating layer located on top of the second level concrete layer 34 and inside the second ring section 35. For example, the second ring section 35 can be made of perlite concrete blocks, and the inner bottom insulation layer 36 can be made of foamed glass blocks, etc. On top of the inner bottom insulation layer 36, for example, a plate made of lightweight aerated concrete may be laid.

[0016] A predetermined gap is provided between the inner tank 4 and the intermediate tank 3, and between the intermediate tank 3 and the outer tank 2. The first gap 11, which is the gap between the inner tank 4 and the intermediate tank 3, and the second gap 12, which is the gap between the intermediate tank 3 and the outer tank 2, are filled with insulating material. Perlite or glass wool can be used as the insulating material. The first gap 11 is filled with a low-boiling-point gas equivalent to the liquid hydrogen LH stored in the inner tank 4, such as hydrogen gas. The second gap 12 is filled with, for example, nitrogen gas.

[0017] [Construction method for triple-walled tanks] Next, the construction method for the triple-walled tank 1 illustrated in Figure 1 will be described. Figure 2 is a process chart showing one embodiment of the construction method for the triple-walled tank 1 according to this disclosure. Figure 2 shows the relationship between processes S1 to S14 performed during the construction period of the triple-walled tank 1 and the construction timing of each part of the triple-walled tank 1. Specifically, for each of the bottom plates 21, 31, 41 of the outer tank 2, intermediate tank 3, and inner tank 4, the roof 23, 33, 43, and side plates 22, 32, 42, the construction period during which the main construction work is actually performed is shown by a solid arrow, and the period after construction is shown by a dotted line, respectively, in Figure 2. For the side plates 22, 32, and 42, the timing of opening the construction opening, which is the entrance / exit for construction, is noted as "open," and the timing of sealing the construction opening is noted as "closed." Note that processes S1 to S14 are not necessarily divided into process units that mark a division in the tank construction procedure, and in some cases, the progress of the construction is simply divided as "process."

[0018] As also noted in Figure 2, a distinctive feature of the construction method in this embodiment is that a roof assembly, formed by temporarily fixing the intermediate tank roof 33 and the inner tank roof 43 to the outer tank roof 23, is created by ground work (step S6), and this roof assembly is then levitated using air lathing (step S8). Figures 3 to 16 schematically show the construction state of the triple-shell tank 1 in steps S1 to S14 shown in Figure 2. In Figures 3 to 16, the portion corresponding to half of the triple-shell tank 1 from the radial center RC is shown in cross-section. Steps S1 to S14 will be explained below with reference to Figures 3 to 16.

[0019] <Process S1> Figure 3 shows the construction status of process S1. In process S1, a portion of the outer tank 2 is installed on the tank foundation 10. Specifically, the outer tank annulare 211, which forms part of the outer tank bottom plate 21, and the outer tank side plate piece 22P1, which forms part of the outer tank side plate 22, are installed near the periphery of the tank foundation 10. The outer tank annulare 211 forms an annular portion near the outer circumference of the disc-shaped outer tank bottom plate 21 and is located below the first ring portion 25. The outer tank annulare 211 has a thicker plate thickness than other parts of the outer tank bottom plate 21 in order to improve load-bearing capacity.

[0020] The outer tank side plate 22 is assembled using multiple side plate pieces, each consisting of a gently curved rectangular plate. More specifically, the side plate pieces are arranged in a ring shape, and adjacent side plate pieces are welded together to form a ring-shaped step. The outer tank side plate 22 is constructed by stacking multiple such ring-shaped steps. The outer tank side plate piece 22P1 shown in Figure 3 is a side plate piece that constitutes the lowest ring-shaped step of the outer tank side plate 22. The outer tank side plate piece 22P1 is erected vertically upward from slightly inside the radially outer periphery of the outer tank annula 211.

[0021] <Process S2> Figure 4 shows the construction status of process S2. In process S2, the outer tank bottom plate 21 and outer tank side plates 22 are constructed. For the outer tank bottom plate 21, the radially inner portion of the outer tank annula 211 is laid. This inner portion is located directly below the outer bottom insulation layer 26. Although not shown in Figure 4, the first level concrete layer 24 shown in Figure 1 is poured on top of the laid outer tank bottom plate 21. First, a portion of the first level concrete layer 24 is poured on top of the outer tank annula 211. After the inner tank roof 43 and intermediate tank roof 33 are constructed and the risk of rainwater intrusion is eliminated, the remaining portion of the first level concrete layer 24 is poured on the inner portion of the outer tank annula 211.

[0022] Regarding the outer tank side plate 22, the outer tank side plate piece 22P2, which constitutes the second annular step, is installed on top of the outer tank side plate piece 22P1, which constitutes the lowest annular step. After the construction of the second annular step, a first opening OP1, which serves as a work opening, is provided in the lowest annular step. The first opening OP1 is created by removing one or more of the multiple outer tank side plate pieces 22P1 that constitute the lowest annular step. Specifically, after arranging multiple outer tank side plate pieces 22P1 in a ring to form an annular step, only the outer tank side plate piece 22P1 corresponding to the position of the first opening OP1 is not welded to the adjacent piece and is removed from the annular step.

[0023] A central roof support frame 51 is installed near the radial center RC of the outer tank bottom plate 21. The central roof support frame 51 is a support frame that allows the dome-shaped inner tank roof 43 to be constructed on the ground side before air racing.

[0024] <Process S3> Figure 5 shows the construction status of process S3. In process S3, the construction of the outer tank side plate 22 continues, and the construction of the inner tank roof 43 begins. For the outer tank side plate 22, the outer tank side plate piece 22P3, which constitutes the third annular step, is installed on top of the outer tank side plate piece 22P2, which constitutes the second annular step. Similarly, after the construction of the third annular step, the first opening OP1, which will serve as a construction opening, is opened by removing one or more outer tank side plate pieces 22P2 from the second annular step. The outer tank side plate piece 22P2 that is removed is the piece located directly above the outer tank side plate piece 22P1 that was removed in the lowest annular step to open the first opening OP1. The reason for opening the first opening OP1 in the outer tank side plate 22 at the height of two annular steps is to match the opening height to the construction openings opened in the intermediate tank side plate 32 and inner tank side plate 42, which are constructed starting from a higher position than the outer tank side plate 22.

[0025] Regarding the inner tank roof 43, the inner tank roof piece 43P, which constitutes the area near the radial center of the inner tank roof 43, is installed on the central roof support frame 51 installed in the previous step S2. Meanwhile, an outer perimeter roof support frame 52 is installed on the upper surface near the radial outer perimeter of the outer tank bottom plate 21. The outer perimeter roof support frame 52 is a support frame that temporarily supports the lower outer edges of the inner tank roof 43 and the intermediate tank roof 33. An inner tank knuckle plate 44 is installed on the upper surface of the outer perimeter roof support frame 52. The inner tank knuckle plate 44 is a plate that connects the upper end of the inner tank side plate 42 to the lower outer edge of the inner tank roof 43.

[0026] <Process S4> Figure 6 shows the construction status of process S4. In process S4, construction of the inner tank roof 43 continues, and construction of the intermediate tank roof 33 begins. For the inner tank roof 43, the inner tank roof piece 43P in the radial center, which was installed in process S3, and the inner tank knuckle plate 44 are connected by an inner tank roof block that was assembled in advance during ground work, thereby ultimately forming a dome-shaped inner tank roof 43. The inner tank roof block consists of a roof frame that serves as a support frame and multiple roof plates attached to this roof frame. The outer edge 43E of the inner tank roof 43 is fixed to the upper end of the inner tank knuckle plate 44. At this point, the inner tank roof 43 is supported by the outer roof frame 52 and becomes self-supporting, so the central roof frame 51 is removed.

[0027] For the intermediate tank roof 33, the intermediate tank roof piece 33P, which constitutes the area near the radial center of the intermediate tank roof 33, is installed on the radial center of the inner tank roof 43, which was completed in process S3. An intermediate tank roof support 61 (first temporary support) is used for this installation. The intermediate tank roof support 61 is interposed between the inner tank roof 43 and the intermediate tank roof 33, and temporarily fixes them at a predetermined distance. A rigid member such as an H-beam can be used as the intermediate tank roof support 61. The temporary fixing can be carried out, for example, by welding the lower end of the H-beam to the inner tank roof 43 via a predetermined backing plate, and then placing and fixing the intermediate tank roof piece 33P on the upper end of the H-beam.

[0028] Construction of the outer tank side plates 22 is also continued as needed. Figure 6 shows the state in which the outer tank side plate piece 22P4, which constitutes the fourth annular stage, has been installed. In addition, the intermediate tank knuckle plate 37 is installed on the upper surface of the outer perimeter roof frame 52. The intermediate tank knuckle plate 37 is a plate that connects the upper end of the intermediate tank side plate 32 to the lower edge of the outer perimeter of the intermediate tank roof 33. Furthermore, blocks that constitute the first ring section 25 are laid on the upper surface near the radial outer perimeter of the outer tank bottom plate 21.

[0029] <Process S5> Figure 7 shows the construction status in process S5. In process S5, construction of the intermediate tank roof 33 continues, and construction of the outer tank roof 23 begins. Also, construction of the intermediate tank bottom plate 31 and intermediate tank side plates 32 begins. For the intermediate tank roof 33, the intermediate tank roof piece 33P at the radial center, which was installed in process S4, and the intermediate tank knuckle plate 37 are connected by intermediate tank roof blocks that were assembled in advance during ground work, thereby ultimately forming a dome-shaped intermediate tank roof 33. The intermediate tank roof block, like the inner tank roof block described above, consists of a roof frame and multiple roof plates. When installing this intermediate tank roof block, the intermediate tank roof support 61 is placed in the appropriate location between the intermediate tank roof 33 and the inner tank roof 43, and the two are temporarily fixed together. The outer edge 33E of the intermediate tank roof 33 is fixed to the upper end of the intermediate tank knuckle plate 37.

[0030] For the outer tank roof 23, the outer tank roof piece 23P, which constitutes the area near the radial center of the outer tank roof 23, is installed on the radial center of the intermediate tank roof 33, which was completed in process S4. For this installation, an outer tank roof central support 62 (second temporary support) is used. The outer tank roof central support 62 is interposed between the intermediate tank roof 33 and the radial center outer tank roof piece 23P, and temporarily fixes the two at a predetermined distance. As the outer tank roof central support 62, an H-beam or a frame assembled from steel materials in a truss structure can be used. The temporary fixing can be carried out by welding the lower end of the H-beam or the like to the intermediate tank roof 33 via a predetermined backing plate, and then placing and fixing the outer tank roof piece 23P on the upper end of the H-beam or the like.

[0031] On top of the first ring section 25 installed in the previous step S4, the intermediate tank annulare 311, which forms part of the intermediate tank bottom plate 31, and the intermediate tank side plate piece 32P1 (side plate piece), which forms part of the intermediate tank side plate 32, are installed. The intermediate tank annulare 311 is an annular portion near the outer circumference of the disc-shaped intermediate tank bottom plate 31 and has a thicker plate thickness than the other parts of the intermediate tank bottom plate 31. The intermediate tank side plate 32 is also assembled by stacking multiple annular steps formed by arranging multiple side plate pieces in an annular shape. The intermediate tank side plate piece 32P1 shown in Figure 7 is a side plate piece that forms the lowest annular step of the intermediate tank side plate 32. The intermediate tank side plate piece 32P1 is erected vertically upward from the radially outer periphery of the intermediate tank annulare 311. The intermediate tank side plate piece 32P1 is also a side plate piece that matches the height of the second annular step of the intermediate tank side plate 32 with the lowest annular step of the inner tank side plate 42, which will be constructed later.

[0032] <Process S6> Figure 8 shows the construction status of process S6. In process S6, the construction of the outer tank roof 23 continues, and finally a roof connecting body 20 is formed in which the three roofs are integrated. Also, the outer tank side plates 22 are installed up to a predetermined height. For the outer tank roof 23, the outer tank roof blocks that were assembled in advance during ground work are connected to the radially central outer tank roof piece 23P that was installed in process S5, thereby finally forming a dome-shaped outer tank roof 23. During this extension, outer tank roof peripheral supports 63 (second temporary supports) made of H-beams or the like are placed in appropriate locations between the intermediate tank roof 33 and the outer tank roof 23, and the two are temporarily fixed together.

[0033] The formation of the roof connector 20 is completed when the construction of the outer tank roof 23 is finished. Specifically, the roof connector 20 is formed when the intermediate tank roof 33 is temporarily fixed on the inner tank roof 43 by the intermediate tank roof support 61, and the outer tank roof 23 is temporarily fixed on the intermediate tank roof 33 by the outer tank roof central support 62 and the outer tank roof peripheral support 63. This formation of the roof connector 20 makes it possible to air race the three roofs as a single unit. The aforementioned supports 61, 62, and 63 serve as support members for the upper roof until air racing is completed, but after air racing they become suspension members for the lower roof.

[0034] Furthermore, in the formed state of the roof connection 20, the gaps between the inner tank roof 43 and the intermediate tank roof 33, and between the intermediate tank roof 33 and the outer tank roof 23, are set to be slightly narrower than the gaps between them in the completed triple-hull tank 1. This is to facilitate the fixing work of the inner tank roof 43 to the inner tank side plate 42, and the fixing work of the intermediate tank roof 33 to the intermediate tank side plate 32, which is performed after air racing.

[0035] The outer tank side plates 22 are constructed by stacking a predetermined number of ring-shaped steps formed by the side plate pieces. This completes the construction of outer tank side plates 22 to a predetermined height around the roof connector 20, making it ready for air racing. The outer perimeter walkway 27 is installed on the top 22T of the outer tank side plates 22. In addition, a portion of the second level concrete layer 34 (not shown in the figure) is poured on top of the intermediate tank annula 311, and blocks constituting the second ring section 35 are laid.

[0036] <Process S7> Figure 9 shows the construction status of process S7. In process S7, mainly preparatory work for aerating is carried out. To form a sealed space, a sealing treatment is applied to the outer peripheral edge 23E of the outer tank roof 23 by attaching a sealing material 28. The sealing material 28 seals the gap between the outer peripheral edge 23E and the inner surface of the outer tank side plate 22. A blower 7 for supplying air for aerating is prepared on the outside of the outer tank side plate 22. A blower duct is connected to the air outlet of the blower 7, and this blower duct is drawn into the inside of the outer tank side plate 22 through the first opening OP1. The first opening OP1 is also sealed to seal the area around the blower duct. Since the outer tank bottom plate 21 has already been completed before process S7, no special sealing treatment is required for the bottom surface. Therefore, at this point, the space enclosed by the outer tank bottom plate 21, the outer tank side plate 22, and the outer tank roof 23 is sealed.

[0037] In parallel with the above aeration preparation work, the inner tank annula 411 is installed on the upper surface of the second ring section 35. The inner tank annula 411 is the annular portion near the outer circumference of the disc-shaped inner tank bottom plate 41.

[0038] <Process S8> Figure 10 shows the state after air lathing in step S8. During air lathing, the blower 7 shown in Figure 9 is operated, supplying air to the sealed space enclosed by the outer tank bottom plate 21, outer tank side plates 22, and outer tank roof 23. The air supply increases the air pressure in the sealed space, and this pressure causes the roof assembly 20 to float. At this time, the outer tank side plates 22 act as guides for the floating roof assembly 20.

[0039] The outer tank roof 23 is directly lifted by air lazing. However, the inner tank roof 43 and the intermediate tank roof 33 are pre-integrated with the outer tank roof 23 by temporary supports 61, 62, and 63. Therefore, the inner tank roof 43 and the intermediate tank roof 33 also lift off together with the outer tank roof 23, suspended from it. In other words, since the roof connecting body 20 is formed in advance, the three roofs 23, 33, and 43 that form the triple-shell structure can be lifted all at once in a single air lazing operation. During air lazing, the lifting posture of the roof connecting body 20 is controlled using balance wires.

[0040] After air lazing, the outer edge 23E of the outer tank roof 23 is fixed to the upper end of the outer tank side plate 22. At this point, the temporary fastening of the roof connector 20 is not released, and the inner tank roof 43 and the intermediate tank roof 33 remain suspended from the outer tank roof 23. The equipment for air lazing is removed. Specifically, the sealing material 28 attached near the outer edge 23E of the outer tank roof 23 is removed, and the blower 7 and the air supply duct are removed.

[0041] <Process S9> Figure 11 shows the construction status of process S9. In process S9, construction of the inner tank side plate 42 begins. The inner tank side plate 42 is also assembled by stacking multiple ring-shaped steps formed by arranging multiple side plate pieces in a ring shape. The inner tank side plate piece 42P1 (side plate piece) that constitutes the lowest ring-shaped step of the inner tank side plate 42 is installed on top of the inner tank annula 411. The inner tank side plate piece 42P1 is erected vertically upward from the radially outer periphery of the inner tank annula 411. Figure 11 shows the state in which the inner tank side plate piece 42P2 that constitutes the second ring-shaped step is installed on top of the lowest inner tank side plate piece 42P1.

[0042] When constructing the inner tank side plate 42, a second opening OP2 is provided as a work opening. The second opening OP2 is opened by removing one or more of the inner tank side plate pieces 42P1 that make up the lowest annular step. The position of the second opening OP2 corresponds to the position of the first opening OP1 opened in the outer tank side plate 22. Specifically, the second opening OP2 and the first opening OP1 are opened at approximately the same position in the circumferential direction of the triple-walled tank 1, and their heights are also approximately the same. In this embodiment, the inner tank side plate piece 42P1 and the second-stage outer tank side plate piece 22P2 are at approximately the same height. In the outer tank side plate 22, the heights of the second opening OP2 and the first opening OP1 are aligned by removing not only the lowest-stage outer tank side plate piece 22P1 but also the second-stage outer tank side plate piece 22P2.

[0043] <Process S10> Figure 12 shows the construction status of process S10. In process S10, the inner tank side plate 42 and the intermediate tank side plate 32 are constructed. For the inner tank side plate 42, the inner tank side plate piece 42P3, which constitutes the third annular step, is installed on top of the inner tank side plate piece 42P2, which constitutes the second annular step. Furthermore, the fourth inner tank side plate piece 42P4 is installed on top of that, and so on, the height of the side plates is gradually increased.

[0044] Similarly, for the intermediate tank side plates 32, the intermediate tank side plate pieces 32P2, 32P3, and 32P4 that constitute the second, third, and fourth ring-shaped stages are sequentially stacked on top of the installed lowest intermediate tank side plate piece 32P1. In this embodiment, the inner tank side plate piece 42Pn and the intermediate tank side plate piece 32Pn (excluding the height-adjusting piece 32P1) have the same height and width. Therefore, the inner tank side plate pieces 42P1, 42P2, and 43P3 shown in Figure 12 and the intermediate tank side plate pieces 32P2, 32P3, and 32P4 are all at the same height.

[0045] In process S10, it is possible to stack one of the annular sections of the inner tank side plate 42 or the intermediate tank side plate 32 first, and then stack the other annular section; however, it is preferable to stack the annular sections of the inner tank side plate 42 and the intermediate tank side plate 32 simultaneously. For example, after stacking the second inner tank side plate piece 42P2 of the inner tank side plate 42, the third intermediate tank side plate piece 32P3 of the intermediate tank side plate 32 is stacked, followed by the third inner tank side plate piece 42P3 of the inner tank side plate 42. By adopting such a construction method, it is possible to improve work efficiency, such as by sharing scaffolding when constructing the inner tank side plate 42 and the intermediate tank side plate 32. Furthermore, for the convenience of crane lifting and assembly work of the side plate pieces, it is preferable to stack the inner tank side plate pieces 42Pn, which are located radially inward, before stacking the intermediate tank side plate pieces 32Pn.

[0046] A third opening OP3 is also provided as a construction opening when the intermediate tank side plate 32 is constructed. The third opening OP3 is opened by removing one or more of the intermediate tank side plate pieces 32P2 that make up the second annular stage. As indicated by the "Open" label in the chart in Figure 2, at process S10, the second opening OP2 is opened in the inner tank side plate 42 and the third opening OP3 is opened in the intermediate tank side plate 32.

[0047] The third opening OP3 is located at the same position as the second opening OP2 on the inner tank side plate 42. More specifically, the second opening OP2 and the third opening OP3 are opened at approximately the same position in the circumferential direction and at approximately the same height. As previously described, the second opening OP2 is located at the same position as the first opening OP1 on the outer tank side plate 22. Therefore, the first opening OP1, the second opening OP2, and the third opening OP3 are opened at approximately the same circumferential and height positions. This allows for efficient movement of workers inside and outside the tank during construction, as well as efficient loading and unloading of materials and construction equipment.

[0048] In step S10, the first level concrete layer 24 (not shown in Figure 12) and the outer bottom insulation layer 26 are sequentially laid on top of the outer tank bottom plate 21. Since the portion of the first level concrete layer 24 above the outer tank annula 211 was completed in step S2, the remaining portion is then constructed. As previously described, the outer bottom insulation layer 26 is constructed by laying insulating block material, such as bubble glass, inside the first ring portion 25.

[0049] <Process S11> Figure 13 shows the construction status of process S11. In process S11, the construction of the inner tank side plates 42 and intermediate tank side plates 32 continues, the inner tank side plates 42 are fixed to the inner tank roof 43, and the intermediate tank bottom plate 31 is laid. For the inner tank side plates 42 and intermediate tank side plates 32, the middle to upper sections of each annular step are installed. In Figure 13, the inner tank side plate 42 is shown with the inner tank side plate piece 42PT, which constitutes the uppermost annular step, assembled one step ahead of the intermediate tank side plates 32.

[0050] The reason for assembling the annular section of the inner tank side plate 42 up to the top section before the intermediate tank side plate 32 is as follows: When lifting the side plate pieces 32P and 42P, "external lifting" is performed by positioning the crane radially outside the side plate and lifting it. This is because both the inner tank side plate 42 and the intermediate tank side plate 32 have assembly jigs including scaffolding on their inner surfaces, and the inner surface is accessible to workers. If the intermediate tank side plate 32 is assembled first, it becomes difficult to lift the inner tank side plate piece 42P due to the inner scaffolding of the intermediate tank side plate 32. For this reason, it is desirable to assemble the inner tank side plate 42 first, create scaffolding on the inside of the intermediate tank side plate 32, and then lift the intermediate tank side plate piece 32P from the outside.

[0051] After the uppermost inner tank side plate piece 42PT is installed, the outer edge of the inner tank roof 43 is fixed to the upper end of the inner tank side plate 42. Prior to this fixing work, the intermediate tank roof support 61 connecting the intermediate tank roof 33 and the inner tank roof 43 is replaced with the first jack 64. After air lathing, with the roof connector 20 still temporarily fixed and the outer tank roof 23 fixed to the outer tank side plate 22, the inner tank roof 43 is suspended from the intermediate tank roof 33 by the intermediate tank roof support 61 at a higher position than the normal height. This is to secure adjustment space when connecting the inner tank roof 43 to the inner tank side plate 42.

[0052] The first jack 64 is positioned appropriately between the intermediate tank roof 33 and the inner tank roof 43, and after the suspension change, it suspends and supports the inner tank roof 43 so that it can be raised and lowered. While the inner tank roof 43 is jacked down by the amount of the lowering adjustment space using the first jack 64, the lower end of the inner tank knuckle plate 44 and the upper end of the uppermost inner tank side plate piece 42PT are aligned. After alignment, the two are fixed in place, and the inner tank 4 is almost completed.

[0053] Furthermore, in step S11, the remaining portion of the intermediate tank bottom plate 31 is laid on top of the outer bottom insulation layer 26. As the intermediate tank annula 311 that constitutes the outer perimeter has already been installed, the inner portion of the intermediate tank bottom plate 31 is laid.

[0054] <Process S12> Figure 14 shows the construction status of process S12. In process S12, the intermediate tank side plate 32 and the intermediate tank roof 33 are fixed together, and the inner bottom insulation layer 36 is laid. Similar to the inner tank roof 43, the jack-down method is also used to fix the intermediate tank roof 33. After the inner tank roof 43 is fixed to the inner tank side plate 42, the intermediate tank side plate piece 32PT, which forms the uppermost annular step of the intermediate tank side plate 32, is installed. Meanwhile, the central support 62 and peripheral support 63 of the outer tank roof, which connect the outer tank roof 23 and the intermediate tank roof 33, are replaced with second jacks 65. The intermediate tank roof 33 is also suspended from the outer tank roof 23 at a position higher than the normal height position by the amount of the adjustment space.

[0055] The second jack 65 is positioned appropriately between the outer tank roof 23 and the intermediate tank roof 33, and after the suspension change, it suspends and supports the intermediate tank roof 33 so that it can be raised and lowered. While the intermediate tank roof 33 is jacked down by the amount of the adjustment space using the second jack 65, the lower end of the intermediate tank knuckle plate 37 and the upper end of the uppermost intermediate tank roof piece 33PT are aligned. After alignment, both are fixed in place, and the intermediate tank 3 is almost completed.

[0056] In step S12, an inner bottom insulation layer 36 is laid on top of the intermediate tank bottom plate 31 (second level concrete layer 34). The inner bottom insulation layer 36 is constructed by laying insulating block material, such as bubble glass, inside the second ring section 35.

[0057] <Process S13> Figure 15 shows the construction status of process S13. In process S13, the inner tank bottom plate 41 is laid, the second opening OP2 is sealed, and the deck is installed. The inner tank bottom plate 41 is laid on top of the inner bottom insulation layer 36. As the inner tank annula 411 that constitutes the outer perimeter has already been installed, the inner tank bottom plate 41 is laid on the inner part of the annula 41.

[0058] After the work inside the inner tank 4 is completed and the scaffolding and other equipment installed inside the inner tank 4 are removed, the second opening OP2 of the inner tank side plate 42 is sealed. This sealing process involves fitting the inner tank side plate piece 42P1, which was extracted from the lowest annular step in process S9, into the second opening OP2, and welding the inner tank side plate piece 42P1 to the surrounding side plate pieces. Figure 15 shows the state in which the second opening OP2 has been sealed.

[0059] Shoulder decks 231 and top decks 232 are installed on top of the outer tank roof 23. The shoulder decks 231 are positioned on the radial outer periphery of the outer tank roof 23. The top decks 232 are positioned in the radial center of the outer tank roof 23. In addition, work such as filling the first tank space 11 and the second tank space 12 with insulation material, and installing various pipes and accessories is also carried out.

[0060] <Process S14> Figure 16 shows the construction status of process S14. In process S14, the third opening OP3 and the first opening OP1 are sealed. The third opening OP3 of the intermediate tank side plate 32 is sealed after the work inside the intermediate tank 3 is completed and the scaffolding and other equipment installed inside the intermediate tank 3 are removed. In this sealing work, the intermediate tank side plate piece 32P2 that was extracted in process S10 is fitted into the third opening OP3, and the intermediate tank side plate piece 32P2 is welded to the surrounding side plate pieces.

[0061] Next, after the work inside the outer tank 2 is completed and the scaffolding and other equipment installed inside the outer tank 2 are removed, the first opening OP1 of the outer tank side plate 22 is sealed. In this sealing process, the outer tank side plate pieces 22P1 and 22P2, which were extracted in processes S2 and S3, are fitted to close the first opening OP1 and then welded together. As described above, the work openings are sealed sequentially in the order of the inner second opening OP2, the intermediate third opening OP3, and the outer first opening OP1, as work inside each side plate is completed.

[0062] [Effects and Effects] According to the construction method for the triple-hull tank described above, a roof assembly 20 is formed by temporarily fixing the inner tank roof 43, the intermediate tank roof 33, and the outer tank roof 23 to each other before air lathing. Specifically, the intermediate tank roof 33 is temporarily fixed to the inner tank roof 43 with an intermediate tank roof support 61, and then the outer tank roof 23 is temporarily fixed to the intermediate tank roof 33 with an outer tank roof central support 62 and an outer tank roof peripheral support 63, thereby creating the roof assembly 20. After forming outer tank side plates 22 that serve as buoyancy guides around this roof assembly 20, the roof assembly 20 is air lathed.

[0063] Here, the outer tank roof 23 is directly air-laid, but the inner tank roof 43 and intermediate tank roof 33 are also held by the outer tank roof 23 and float together as a single unit. In other words, the inner tank roof 43 and intermediate tank roof 33 float while suspended from the outer tank roof 23. That is, each roof of the triple shell is created using ground-based work, temporarily fixed and integrated, and then floated all at once with a single air-laid operation. Therefore, most of the construction work for each roof of the triple shell can be carried out at low altitude in parallel with the construction work of the side plates, etc., thus contributing to a reduction in construction time. Furthermore, the inner tank side plates 42 and intermediate tank side plates 32 can be constructed after the outer tank 2 is formed by fixing the outer tank roof 23 to the outer tank side plates 22. That is, the construction work for the inner tank side plates 42 and intermediate tank side plates 32 can be carried out in the space covered by the outer tank 2. Therefore, the construction work can be carried out without being affected by the weather, and there is also the advantage of avoiding a decrease in welding quality due to the presence of moisture.

[0064] [Modified Embodiment] The embodiments of the construction method for a triple-hulled tank according to this disclosure have been described above, but this disclosure is not limited to the embodiments described above. For example, the following modified embodiments can be taken for the construction method for a triple-hulled tank described above.

[0065] (1) Necessary structures and facilities may be attached near the triple-walled tank 1 described above. For example, a containment dike may be erected around the triple-walled tank 1 to prevent the spread of liquid in the event of a leak in the tank during a disaster. The containment dike can be constructed, for example, of PC (prestressed concrete). The containment dike may be constructed integrally with the metal outer tank 2. Specifically, the PC constituting the containment dike may be constructed in close contact with the outer surface of the outer tank side plate 22. In this case, the strength of the outer tank side plate 22, which serves as a guide when air-racing the roof connector 20, can be increased.

[0066] (2) Various structures may be added to reinforce the strength of the triple-hulled tank 1. For example, anchor straps may be provided to connect the intermediate tank side plates 32 and / or the inner tank side plates 42 to the tank foundation 10.

[0067] (3) A connecting pipe may be attached to the inner tank roof 43 to connect the internal space of the inner tank 4 with the space between the first tanks 11. According to this modification, hydrogen gas vaporized from the liquid hydrogen LH stored in the inner tank 4 can be circulated to the space between the first tanks 11. In other words, the cooling effect can be enhanced by utilizing the stored liquid hydrogen LH.

[0068] (4) In the above embodiment, an example was shown in which the first opening OP1, the second opening OP2, and the third opening OP3 are opened at the same position and at approximately the same height in the circumferential direction of the triple-shell tank 1. These openings OP1, OP2, and OP3 may be opened at different positions in the circumferential direction of the triple-shell tank 1, or at different heights.

[0069] [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations.

[0070] The construction method for a triple-walled tank according to this disclosure is a construction method for a triple-walled tank comprising an inner tank, an intermediate tank, and an outer tank, each having a roof and side plates, wherein the intermediate tank roof is temporarily fixed on the inner tank roof, and the outer tank roof is further temporarily fixed on the intermediate tank roof to form a roof assembly, an outer tank side plate of a predetermined height is constructed around the roof assembly, a sealing treatment is applied between the outer edge of the outer tank roof and the inner surface of the outer tank side plate to form a sealed space, and air is supplied to the sealed space to air-race the roof assembly, fixing the outer tank roof and the outer tank side plate, constructing the inner tank side plate and the intermediate tank side plate, the temporary fixing of the roof assembly is released, and the inner tank roof and the inner tank side plate are fixed, and the intermediate tank roof and the intermediate tank side plate are fixed.

[0071] According to this construction method, before air lathing, a roof assembly is formed in which the inner tank roof, intermediate tank roof, and outer tank roof are temporarily fixed to each other. Subsequently, the outer tank side plates are formed around the roof assembly, and then the roof assembly is air-lathed. Although the outer tank roof is directly air-lathed, the inner tank roof and intermediate tank roof are also held by the outer tank roof and float up as a single unit. In other words, each roof of the triple shell is created by ground work, temporarily fixed and integrated, and then floated up all at once with a single air lathing. Therefore, since most of the construction work for each roof of the triple shell can be performed at low altitude, it contributes to shortening the construction period. Furthermore, after the outer tank is formed by fixing the outer tank roof to the outer tank side plates, the inner tank side plates and intermediate tank side plates are constructed. In other words, the construction work for the inner tank side plates and intermediate tank side plates can be carried out while covered by the outer tank, which has the advantage of not being affected by weather.

[0072] In the construction method of the triple-hulled tank described above, it is desirable to form the outer tank bottom plate, which constitutes the bottom of the area surrounded by the outer tank side plates, at least before the air lathing.

[0073] This construction method allows for the formation of a sealed space necessary for aeration by pre-forming the bottom plate of the outer tank.

[0074] In the construction method for the triple-hulled tank described above, it is desirable to form the roof assembly by first forming the outer tank bottom plate, then installing a roof frame on the outer tank bottom plate, then installing the inner tank roof on the roof frame, then installing a first temporary support on the inner tank roof, then installing the intermediate tank roof on the first temporary support, then installing a second temporary support on the intermediate tank roof, and finally installing the outer tank roof on the second temporary support.

[0075] According to this construction method, the intermediate tank roof and the outer tank roof are sequentially installed on top of the innermost tank roof, thereby forming a roof assembly. Therefore, the roof assembly can be formed with high work efficiency.

[0076] In the construction method for the triple-walled tank described above, the inner tank side plates and the intermediate tank side plates are assembled by stacking multiple ring-shaped sections formed by arranging multiple side plate pieces in a ring shape, and it is desirable that the ring-shaped sections of the inner tank side plates and the ring-shaped sections of the intermediate tank side plates be stacked in parallel.

[0077] This construction method allows for increased work efficiency, such as the ability to share scaffolding during the construction of the inner tank side plates and intermediate tank side plates, ultimately contributing to a shorter construction period.

[0078] In the construction method for the triple-hulled tank described above, the inner tank side plates and the intermediate tank side plates are assembled by stacking multiple ring-shaped steps formed by arranging multiple side plate pieces in a ring shape, and it is desirable to assemble the ring-shaped steps of the inner tank side plates up to the top step before the intermediate tank side plates, and to fix the top ring-shaped step to the outer edge of the inner tank roof.

[0079] According to this construction method, the roof and side panels of the inner tank, which is located inside the intermediate tank, are fixed first, which improves work efficiency compared to the case where the roof and side panels of the intermediate tank are fixed first.

[0080] In the construction method for the triple-hulled tank described above, it is desirable that a first work opening, which is an entrance / exit for construction work, be opened in the outer tank side plate when the outer tank side plate is constructed, a second work opening be opened in the inner tank side plate when the inner tank side plate is constructed, a third work opening be opened in the intermediate tank side plate when the intermediate tank side plate is constructed, the second work opening be sealed after the work inside the inner tank is completed, then the third work opening be sealed after the work inside the intermediate tank is completed, and then the first work opening be sealed after the work inside the outer tank is completed.

[0081] This construction method allows for the timely opening of work openings in the outer tank side panels, intermediate tank side panels, and inner tank side panels, enabling various construction works to proceed smoothly. [Explanation of symbols]

[0082] 1 Triple-walled tank 2 Outer tank 20 Roof Connecting Unit 21 Outer tank bottom plate 22 Outer tank side plate 23 Outer tank roof 3 Intermediate tank 31 Intermediate tank bottom plate 32 Intermediate tank side plate 33 Intermediate tank roof 4 Inner tank 41 Inner tank bottom plate 42 Inner tank side plate 43 Inner tank roof 51 Central roof support structure (roof support structure) 52 Perimeter roof support structure (roof support structure) 61 Intermediate tank roof support (first temporary support) 62. Central support for the outer tank roof (second temporary support) 63. Outer tank roof perimeter support (second temporary support) OP1, OP2, OP3 1st opening, 2nd opening, 3rd opening

Claims

1. A method for constructing a triple-hulled tank comprising an inner tank, an intermediate tank, and an outer tank, each having a roof and side panels, By temporarily fixing the intermediate tank roof onto the inner tank roof, and then temporarily fixing the outer tank roof onto the intermediate tank roof, a roof connecting body is formed. An outer tank side plate of a predetermined height is constructed around the aforementioned roof connecting body, A sealed space is formed by applying a sealing treatment between the outer edge of the outer tank roof and the inner surface of the outer tank side plate, and air is supplied to the sealed space to air-race the roof connecting body. The outer tank roof and the outer tank side plate are fixed together. Construct the inner tank side plates and the intermediate tank side plates, release the temporary fixing of the roof connector, fix the inner tank roof and the inner tank side plates, and fix the intermediate tank roof and the intermediate tank side plates. Construction method for triple-walled tanks.

2. In the construction method for a triple-walled tank according to claim 1, A method for constructing a triple-walled tank, wherein the outer tank bottom plate, which constitutes the bottom of the area surrounded by the outer tank side plates, is formed at least before the air lathing.

3. In the construction method for a triple-walled tank according to claim 2, After forming the outer tank bottom plate, a roof frame is installed on the outer tank bottom plate. The inner tank roof is installed on the aforementioned roof frame, and the first temporary support is installed on the inner tank roof. The intermediate tank roof is installed on the first temporary support, and a second temporary support is installed on the intermediate tank roof. A method for constructing a triple-hull tank, comprising forming the roof assembly by installing the outer tank roof on the second temporary support.

4. In the construction method for a triple-walled tank according to any one of claims 1 to 3, The inner tank side plate and the intermediate tank side plate are assembled by stacking multiple ring-shaped steps, each formed by arranging multiple side plate pieces in a ring shape, and A method for constructing a triple-walled tank, comprising stacking the annular steps of the inner tank side plate and the annular steps of the intermediate tank side plate in parallel.

5. In the construction method for a triple-walled tank according to any one of claims 1 to 3, The inner tank side plate and the intermediate tank side plate are assembled by stacking multiple ring-shaped steps, each formed by arranging multiple side plate pieces in a ring shape, and A method for constructing a triple-walled tank, comprising assembling the annular step of the inner tank side plate up to the uppermost step before the intermediate tank side plate, and fixing the uppermost annular step to the outer edge of the inner tank roof.

6. In the construction method for a triple-walled tank according to any one of claims 1 to 5, When constructing the outer tank side plate, a first construction opening, which is an entrance / exit for construction work, is opened in the outer tank side plate. When the inner tank side plate is constructed, a second construction opening is made in the inner tank side plate, and when the intermediate tank side plate is constructed, a third construction opening is made in the intermediate tank side plate. After the work inside the inner tank is completed, the second work opening is sealed, and then after the work inside the intermediate tank is completed, the third work opening is sealed. A method for constructing a triple-walled tank, wherein the first work opening is sealed after the work inside the outer tank is completed.

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