Double pipe for transferring low-temperature fluid

Abstract

A double pipe (1), which comprises an inner pipe (3) for passing a low-temperature fluid and an outer pipe (5) that covers the outer side of the inner pipe and forms a heat insulating layer (7) between the outer pipe and the inner pipe, comprises a thrust support structure (9) between the inner pipe (3) and the outer pipe (5). The thrust support structure comprises: a first bearing member (11) that is fixed to an outer peripheral surface (3a) of the inner pipe (3) and that has a first bearing surface (11a) facing a first direction (D1) along an axis (A) of the double pipe (1); a second bearing member (13) that is fixed to an inner peripheral surface (5a) of the outer pipe (5) and has a second bearing surface (13a) facing a second direction (D2) opposite to the first direction (D1); and a first intermediate bearing member (15) that is formed from a heat insulating material and is disposed between the first bearing surface (11a) of the first bearing member (11) and the second bearing surface (13a) of the second bearing member (13).

Description

Double piping for low temperature fluid transfer Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2023-203306, filed November 30, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a double pipe used for transferring cryogenic fluids.

[0003] Patent Document 1 proposes the use of a double-wall vacuum insulated pipe as a pipe for transporting a cryogenic fluid such as liquefied gas. In the double wall pipe, a thrust is generated in the inner pipe through which the cryogenic fluid passes due to pressure from the internal fluid. Conventionally, one possible structure for preventing the inner pipe from moving due to such thrust is to install a rod-shaped support member spanning between the outer pipe and the inner pipe to limit the axial movement of the inner pipe relative to the outer pipe.

[0004] Utility Model Publication No. 59-115192

[0005] Conventionally, rod-shaped support members have been made of the same metal material as the piping to firmly secure them to the inner and outer pipes. In this case, the cold heat from the liquefied gas passing through the inner pipe is transferred to the outer pipe via the metal support member. Therefore, to prevent heat transfer to the outer pipe, the support member must be made longer to ensure a sufficient heat transfer distance. This requires a large installation space and affects the piping layout. Furthermore, since the rod-shaped support member is connected from the inner circumferential surface of the outer pipe to the outer circumferential surface of the inner pipe by welding, for example, it must be welded after the outer and inner pipes are assembled, making the installation process cumbersome.

[0006] In order to solve the above-mentioned problems, an object of the present disclosure is to reduce the size of a thrust support structure used in a double-structured pipe for transferring cryogenic fluid and to facilitate the installation work thereof.

[0007] In order to solve the above problems, the double pipe for transferring a cryogenic fluid according to the present disclosure is a double pipe comprising: an inner pipe through which a cryogenic fluid passes; and an outer pipe covering the outside of the inner pipe and forming an insulating layer between the inner pipe and the outer pipe, wherein the thrust support structure is provided between the inner pipe and the outer pipe, and the thrust support structure comprises: a first support member fixed to the outer peripheral surface of the inner pipe and having a first support surface facing in a first direction along the axis of the double pipe; a second support member fixed to the inner peripheral surface of the outer pipe and having a second support surface facing in a second direction opposite to the first direction; and a first intermediate support member formed from an insulating material and arranged between the first support surface of the first support member and the second support surface of the second support member.

[0008] According to the double piping for transferring cryogenic fluids disclosed herein, the thrust support structure consisting of the first support member, the second support member, and the first intermediate support member can be made smaller than conventional structures, and its installation work can be made easier.

[0009] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure, and in particular, any combination of two or more of the claims set forth in the claims is included in the present disclosure.

[0010] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the accompanying claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts. FIG. 1 is a longitudinal sectional view schematically showing the general configuration of a double pipe for transferring a cryogenic fluid according to one embodiment of the present disclosure. FIG. 2 is a transverse sectional view taken along line II-II schematically showing the general configuration of the double pipe for transferring a cryogenic fluid of FIG. 1. FIG. 3 is a longitudinal sectional view schematically showing the general configuration of a double pipe for transferring a cryogenic fluid according to another embodiment of the present disclosure. FIG. 4 is a longitudinal sectional view schematically showing a modified example of the embodiment of FIG.

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 shows a double pipe 1 for transferring a cryogenic fluid according to one embodiment of the present disclosure. In the following description, this cryogenic fluid transfer pipe 1 will be simply referred to as the "double pipe 1." The double pipe 1 of this embodiment is configured as a vacuum insulated pipe having a double structure. That is, the double pipe 1 is composed of an inner pipe 3 through which a cryogenic fluid passes and an outer pipe 5 that covers the outside of the inner pipe 3. The inner pipe 3 and the outer pipe 5 of the double pipe 1 are arranged concentrically, i.e., so as to share the same axis C. A vacuum insulating layer 7 is formed in the radial gap between the inner pipe 3 and the outer pipe 5. However, the double pipe 1 does not have to be a vacuum insulated pipe. For example, an insulating material may be provided in the space between the inner pipe 3 and the outer pipe 5 to form an insulating layer. In this specification, the axial direction, radial direction, and circumferential direction of the double pipe 1 will be simply referred to as the "axial direction," the "radial direction," and the "circumferential direction," respectively. The inner pipe 3 and the outer pipe 5 are made of a metal material such as stainless steel. However, the material of the inner tube 3 and the outer tube 5 is not limited to stainless steel.

[0012] The double pipe 1 is used in liquefied gas storage facilities such as a liquefied gas storage ship or an onshore liquefied gas storage base. In this specification, the term "liquefied gas storage ship" refers to a ship that has the function of storing liquefied gas. In addition to liquefied gas carriers, liquefied gas storage ships also include, for example, liquefied gas fuel ships and bunkering ships that supply liquefied gas to other ships. However, the liquefied gas storage facility is not limited to ships as long as it has the structure and function to store liquefied gas, and may be, for example, an onshore liquefied gas storage facility or a plant that uses liquefied gas.

[0013] The cryogenic fluid transported through the double pipe 1 is, for example, ammonia (LNH ３ , about -30°C), liquefied petroleum gas (LPG, about -45°C), liquefied carbon dioxide (LCO ２ , about -80°C), liquefied ethylene gas (LEG, about -100°C), liquefied natural gas (LNG, about -160°C), liquefied nitrogen (LN ２ , approximately -200°C), liquefied hydrogen (LH ２The cryogenic fluid is a liquefied gas such as liquefied hydrogen (LHe, approximately -250°C), liquefied helium (LHe, approximately -270°C), etc. In this embodiment, liquefied hydrogen is transferred through the double pipe 1. However, the cryogenic fluid referred to in this specification includes not only liquefied gas but also low-temperature vaporized gas generated from liquefied gas. The double pipe 1 of the present disclosure can be applied to equipment that transfers not only liquefied gas but also low-temperature vaporized gas.

[0014] The inner tube 3 through which such a low-temperature fluid passes is subjected to pressure from the internal fluid, resulting in a thrust force acting in the axial direction.

[0015] Therefore, the double pipe 1 of this embodiment is provided with a thrust support structure 9 that supports a thrust acting in the axial direction on the inner pipe 3. The thrust support structure 9 is made up of a first support member 11, a second support member 13, and a first intermediate support member 15 arranged between these first and second support members 11, 13. The thrust support structure 9 supports a thrust acting in one direction along the axis C of the double pipe 1. In this embodiment, the thrust support structure 9 supports a thrust acting in a first direction D1 along the axis C of the double pipe 1.

[0016] Specifically, in this embodiment, as shown in FIG. 1 , the first support member 11 is fixed to the outer peripheral surface 3a of the inner pipe 3. The first support member 11 has a first support surface 11a facing a first direction D1 along the axis C of the double pipe 1. The second support member 13 is fixed to the inner peripheral surface 5a of the outer pipe 5 and has a second support surface 13a facing a second direction D2 opposite to the first direction D1. The first support member 11 and the second support member 13 are attached to the outer peripheral surface 3a of the inner pipe 3 and the inner peripheral surface 5a of the outer pipe 5, respectively, by welding, for example. The first support member 11 and the second support member 13 are made of the same material as the double pipe 1 so as to be firmly fixed to the inner pipe 3 and the outer pipe 5. However, the attachment method and material of the first support member 11 and the second support member 13 are not limited to these examples.

[0017] In this embodiment, the first support member 11 includes a first plate-shaped portion 11b and a first rib 11c that supports the first plate-shaped portion 11b. The first plate-shaped portion 11b extends radially from the outer peripheral surface 3a of the inner tube 3 and has a first support surface 11a. The first rib 11c is provided on the surface of the first plate-shaped portion 11b opposite the first support surface 11a. Similarly, the second support member 13 includes a second plate-shaped portion 13b and a second rib 13c that supports the second plate-shaped portion 13b. The second plate-shaped portion 13b extends radially from the inner peripheral surface 5a of the outer tube 5 and has a second support surface 13a. The second rib 13c is provided on the surface of the second plate-shaped portion 13b opposite the second support surface 13a. The plate-like portions 11b, 13b and the ribs 11c, 13c of each support member 11, 13 may be formed as an integral part, or may be formed by joining separately formed parts by, for example, welding. Furthermore, the cross-sectional shape of each support member 11, 13 along the axis C of the double pipe 1 is not limited to the trapezoid shown in the figure, but may be any shape such as a triangle or a rectangle.

[0018] The first support member 11 and the second support member 13 each face the pipe surface opposite the fixed portion via a radial gap. That is, the first support member 11 fixed to the inner pipe 3 faces the inner circumferential surface 5a of the outer pipe 5 via a radial gap, and the second support member 13 fixed to the outer pipe 5 faces the outer circumferential surface 3a of the inner pipe 3 via a radial gap. If these support members 11, 13 were in contact with the pipe surface on the opposite side, cold would be transferred from the inner pipe 3 to the outer pipe 5. The radial gap prevents contact between the inner pipe 3 and outer pipe 5, both made of metal, and the support members 13, 11, preventing a decrease in thermal insulation.

[0019] The first intermediate support member 15 is disposed between the first support surface 11a of the first support member 11 and the second support surface 13a of the second support member 13. In this embodiment, as shown in FIG. 2 , the first support member 11 and the second support member 13 overlap in the radial direction when viewed in the axial direction. Specifically, the first plate-shaped portion 11b of the first support member 11 and the second plate-shaped portion 13b of the second support member 13 overlap in the radial direction when viewed in the axial direction. The first intermediate support member 15 is disposed in a portion where the two support members 11, 13 overlap in the radial direction. By disposing the first support member 11 and the second support member 13 in this manner so as to have a radially overlapping portion, the first intermediate support member 15 can be disposed in this overlapping portion to reliably support the thrust acting on the inner pipe 3.

[0020] The first intermediate support member 15 is formed from a thermal insulating material. The first intermediate support member 15 is preferably formed from a thermal insulating material such as glass fiber reinforced plastic (GFRP). However, the thermal insulating material forming the first intermediate support member 15 is not limited to this example. Any high-strength thermal insulating material that does not release gas under vacuum may be used. In addition to GFRP, for example, polyether ether ketone (PEEK) may be used. The first intermediate support member 15 is attached to either the first support member 11 or the second support member 13. The first intermediate support member 15 can be attached by any method, for example, by using bolts.

[0021] In this embodiment, the first intermediate support member 15 is formed in a plate shape extending in the circumferential direction. In this embodiment, the first intermediate support member 15 has a rectangular cross section and does not contact either the inner pipe 3 or the outer pipe 5, as shown in the longitudinal cross section of FIG. 1 . However, the first intermediate support member 15 may be in contact with one or both of the inner pipe 3 and the outer pipe 5. In this case, the first intermediate support member 15 can function as a spacer that maintains the distance between the inner pipe 3 and the outer pipe 5. Furthermore, the first intermediate support member 15 can have any shape as long as it can receive a thrust between the first support surface 11 a of the first support member and the second support surface 13 a of the second support member 13.

[0022] The circumferential range in which each support member 11, 13, 15 constituting the thrust support structure 9 is provided may be set appropriately depending on the thrust acting on the inner pipe 3. In this embodiment, as shown in FIG. 2 , each support member 11, 13, 15 is provided at multiple circumferential locations (four locations in this example) at equal circumferential intervals. However, the number of locations, circumferential intervals, and shape of each support member 11, 13, 15 can be determined arbitrarily and are not limited to those shown in the figure. For example, in this embodiment, each support member 11, 13, 15 is fan-shaped when viewed axially as shown in FIG. 2 , but it may also be shaped, for example, as a rectangle with one side curved along the pipe surface. In this embodiment, the first and second plate-shaped portions 11b, 13b of the first and second support members 11, 13 extend over a portion of the circumferential direction of the inner pipe 3 and the outer pipe 5, respectively. The first intermediate support member 15 extends over the same circumferential range as the first and second plate-shaped portions 11b, 13b. In this embodiment, the first and second plate-shaped portions 11b, 13b are supported by a single rib 11c, 13c, respectively. However, multiple ribs may be provided on each plate-shaped portion 11b, 13b. The spacing between the ribs 11c, 13c can be determined appropriately depending on, for example, the required strength. The radial positions of the first rib 11c and the second rib 13c supporting the first plate-shaped portion 11b and the second plate-shaped portion 13b, respectively, do not need to be aligned.

[0023] By limiting the circumferential range in which the support members 11, 13, 15 constituting the thrust support structure 9 are arranged to a portion of the circumferential direction in this manner, the thrust support structure 9 can be installed in a required location according to the thrust acting on the inner pipe 3. This reduces the amount of material required, leading to cost savings and enabling greater freedom in piping layout.

[0024] However, the circumferential range in which each of the support members 11, 13, and 15 constituting the thrust support structure 9 is provided is not limited to this example. For example, each of the support members 11, 13, and 15 may be ring-shaped. With this configuration, the thrust can be distributed over a wide area and a larger thrust can be supported. Furthermore, the circumferential ranges in which each of the support members 11, 13, and 15 is provided do not need to completely coincide with each other.

[0025] According to the double pipe 1 of this embodiment, the thrust support structure 9 supports a thrust acting in the first direction D1 of the inner pipe 3. This thrust support structure 9 is composed of a first support member 11, a second support member 13, and a first intermediate support member 15 formed of a heat insulating material, thereby enabling the thrust support structure to be made more compact than conventional structures that used long metal support members to ensure a heat transfer distance. Furthermore, compared to conventional structures in which support members were welded so as to span the inner pipe and the outer pipe, the first support member 11 and the second support member 13 are attached separately to the double pipe 1, and the first intermediate support member 15 is fixed to one of the support members, thereby facilitating the installation of the thrust support structure.

[0026] In this embodiment, as shown in Fig. 1, the inner pipe 3 is provided with an expansion / contraction section 17 that absorbs changes in the axial length of the inner pipe 3. In this embodiment, the inner pipe 3 has a bellows as the expansion / contraction section 17. Note that the expansion / contraction section 17 may be configured to accommodate, for example, radial displacement in addition to changes in the axial length of the inner pipe 3. With this configuration, thermal contraction of the inner pipe 3 can be absorbed.

[0027] 2 , the thrust support structure 9, which is made up of the first support member 11, the second support member 13, and the first intermediate support member 15, has a communicating gap G that communicates with the vacuum insulation layer 7 through the thrust support structure 9. The specific form of the communicating gap G is not particularly limited, but for example, in the case where the first and second plate-shaped portions 11 b, 13 b and the first intermediate support member 15 are present only in a portion of the circumferential direction, as in the present embodiment, the communicating gap G is formed by a portion in the circumferential direction where the first and second plate-shaped portions 11 b, 13 b and the first intermediate support member 15 are not present. Another exemplary form of the communicating gap G is when the first and second plate-shaped portions 11 b, 13 b and the first intermediate support member 15 extend over the entire periphery and the first intermediate support member 15 is in contact with the inner pipe 3 and the outer pipe 5, the communicating gap G can be provided as a hole penetrating these. If the first intermediate support member 15 is in contact with only one of the inner pipe 3 and the outer pipe 5, or if it is in contact with neither the inner pipe 3 nor the outer pipe 5, a hole serving as a communicating gap G can be provided in the plate-like portion on the side of the first intermediate support member 15 that is not in contact with the inner pipe 3 and / or the outer pipe 5. By providing the communicating gap G, if the insulating layer 7 is a vacuum insulating layer, the vacuum insulating layers 7 on both sides of the thrust support structure can be evacuated simultaneously using a common vacuum pump, making vacuum management easier. However, providing the communicating gap G is not essential.

[0028] In one modification of this embodiment, as shown in FIG. 3 , a second thrust support structure 19 is provided in the double pipe 1. The second thrust support structure 19 includes a third support member 21, a fourth support member 23, and a second intermediate support member 25 disposed between the third and fourth support members 21, 23. Similar to the thrust support structure 9 described above, the second thrust support structure 19 supports a thrust acting in one direction along the axis C of the double pipe 1. In this embodiment, the second thrust support structure 19 supports a thrust acting in a second direction D2 along the axis C of the double pipe 1. By providing these thrust support structures 9, 19, it is possible to support thrusts acting in both directions D1, D2 along the axis C of the double pipe 1.

[0029] 3, the third support member 21 is fixed to the outer peripheral surface 3a of the inner pipe 3 and has a third support surface 21a facing the second direction D2. The fourth support member 23 is fixed to the inner peripheral surface 5a of the outer pipe 5 and has a fourth support surface 23a facing the first direction D1. The attachment method and materials for the third support member 21 and the fourth support member 23 are similar to those for the first support member 11 and the second support member 13, and therefore will not be described here.

[0030] The second intermediate support member 25 is disposed between the third support surface 21 a of the third support member 21 and the fourth support surface 23 a of the fourth support member 23, and is made of a heat insulating material. The mounting method, material, and shape of the second intermediate support member 25 are the same as those of the first intermediate support member 15, and therefore will not be described here.

[0031] By providing thrust support structures 9 and 19, in addition to being able to support the thrust acting in the first direction D1 on the double pipe 1 with the thrust support structure 9, the thrust support structure 19 can also support thrusts acting in the second direction D2, such as seismic forces.

[0032] In a further modification of this embodiment, as shown in FIG. 4 , a thrust support structure 29 is provided in the double pipe 1. Simply put, the thrust support structure 29 is a structure in which the first support member 11 and the third support member 21 of the thrust support structures 9 and 19 are integrated together. Specifically, the thrust support structure 29 includes a second support member 13, a first intermediate support member 15, a shared intermediate support member 31, a second intermediate support member 25, and a fourth support member 23. The second support member 13 and the fourth support member 23 are fixed to the inner circumferential surface 5 a of the outer pipe 5, and the shared intermediate support member 31 is fixed to the outer circumferential surface 3 a of the inner pipe 3. The first intermediate support member 15 is disposed between the second support member 13 and the shared intermediate support member 31, and the second intermediate support member 25 is disposed between the shared intermediate support member 31 and the fourth support member 23. In this case, it is also possible to support the thrust acting in both directions along the axis C of the double pipe 1. Furthermore, since the number of parts is smaller than in the modified example shown in Figure 3, the burden of installing the thrust support structure is reduced.

[0033] In the illustrated example, the shared intermediate support member 31 is fixed to the outer peripheral surface 3a of the inner pipe 3, but the shared intermediate support member 31 may be fixed to the inner peripheral surface 5a of the outer pipe 5, and the support members on both sides may be fixed to the outer peripheral surface 3a of the inner pipe 3. The shared intermediate support member 31 may extend over the entire circumference of the outer peripheral surface 3a of the inner pipe 3 or the inner peripheral surface 5a of the outer pipe 5, or over a portion of the circumference.

[0034] 4, the shared intermediate support member 31 is a member including shared intermediate plate-shaped portions 31b, 31b on both sides and a shared intermediate rib 31c provided therebetween. However, the shared intermediate support member 31 is not limited to the example shown in the figure. For example, the shared intermediate plate-shaped portions 31b, 31b and the shared intermediate rib 31c may be integrally formed, or the shared intermediate support member 31 may be a ring-shaped member with a rectangular cross section. In this modification, the communication gap G can also be provided as a circumferential gap or a through-hole, as appropriate, depending on the circumferential range and shape of the second plate-shaped portion 13b, the fourth plate-shaped portion 23b, and the shared intermediate support member 31.

[0035] In the modified example shown in FIG. 4 , the common intermediate support member 31 is fixed, for example, by welding, similar to the first support member 11 and the third support member 21, and is made of the same material as the double pipe 1. Although not shown, instead of forming the common intermediate support member 31 from common intermediate plate portions 31b, 31b and a common intermediate rib 31c, the common intermediate support member 31 may be a ring-shaped member with a rectangular cross section composed of a base fixed to the outer peripheral surface 3a of the inner pipe 3 and an insulating material fixed to the outer pipe side portion of the base, with the insulating material of the ring-shaped member sandwiched between the first intermediate support member 15 and the second intermediate support member 25. In this case, the number of metal components constituting the thrust support structure is reduced, further suppressing the transfer of cold and heat and improving the insulating performance of the double pipe 1. Furthermore, if necessary, the inner pipe side insulating material can be dimensioned to contact the outer peripheral surface of the outer pipe 5, thereby limiting radial movement of the inner pipe 3.

[0036] Although detailed explanation will be omitted, the double pipe 1 according to this embodiment may, if necessary, be provided with structural elements other than those shown in the figure, such as a spacer that restricts the relative radial movement between the inner pipe 3 and the outer pipe 5, and an expansion / contraction-permitting portion provided on the outer pipe.

[0037] The double pipe 1 according to the first aspect of this embodiment described above is a double pipe 1 including an inner pipe 3 shown in FIG. 1 for passing a low-temperature fluid therethrough, and an outer pipe 5 that covers the outside of the inner pipe 3 and forms an insulating layer 7 between the inner pipe 3 and the outer pipe 5. The double pipe 1 includes a thrust support structure 9 between the inner pipe 3 and the outer pipe 5. The thrust support structure 9 includes a first support member 11 fixed to the outer peripheral surface 3a of the inner pipe 3 and having a first support surface 11a facing a first direction D1 along the axis C of the double pipe 1, a second support member 13 fixed to the inner peripheral surface 5a of the outer pipe 5 and having a second support surface 13a facing a second direction D2 opposite to the first direction D1, and a first intermediate support member 15 made of an insulating material and arranged between the first support surface 11a of the first support member 11 and the second support surface 13a of the second support member 13. According to this configuration, the thrust support structure 9 consisting of the first support member 11, the second support member 13, and the first intermediate support member 15 can be made smaller than conventional structures, and its installation work can be made easier.

[0038] The double pipe 1 according to the second aspect of the present embodiment is the double pipe according to the first aspect, wherein the inner pipe 3 may include an expansion / contraction allowing portion 17 that absorbs changes in the axial length of the inner pipe 3. With this configuration, thermal contraction of the inner pipe 3 can be absorbed.

[0039] 3 , the double pipe 1 according to the third aspect of the present embodiment may include the double pipe according to the first or second aspect, wherein the thrust support structure 19 includes a third support member 21 fixed to the outer peripheral surface 3 a of the inner pipe 3 and having a third support surface 21 a facing the second direction D2, a fourth support member 23 fixed to the inner peripheral surface 5 a of the outer pipe 5 and having a fourth support surface 23 a facing the first direction D1, and a second intermediate support member 25 formed of a thermal insulating material and disposed between the third support surface 21 a of the third support member 21 and the fourth support surface 23 a of the fourth support member 23. With this configuration, in addition to the thrust support structure 9 supporting the thrust acting on the double pipe 1 in the first direction D1, the thrust support structure 19 can also support a thrust acting in the second direction D2, such as an earthquake force.

[0040] The double pipe 1 according to the fourth aspect of the present embodiment may be the double pipe according to the third aspect, wherein the first support member 11 and the third support member 21 of the thrust support structure 9 are integrally formed to form a common intermediate support member 31. With this configuration, the number of parts is reduced, thereby reducing the burden of the installation work of the thrust support structure.

[0041] The double pipe 1 according to a fifth aspect of this embodiment may be the double pipe according to any one of the first to third aspects, wherein the first support member 11 and the second support member 13 shown in Fig. 2 overlap in the radial direction when viewed in the axial direction. According to this configuration, the first support member 11 and the second support member 13 are arranged to have a radially overlapping portion, and a first intermediate support member 15 is arranged in the overlapping portion, thereby making it possible to reliably support the thrust acting on the inner pipe 3.

[0042] The double pipe 1 according to a sixth aspect of the present embodiment is the double pipe according to any one of the first to fourth aspects, wherein the thrust support structure 9 consisting of the first support member 11, the second support member 13, and the first intermediate support member 15 may have a communication gap G that communicates with the insulating layer 7 through the thrust support structure 9. According to this configuration, when the insulating layer 7 is a vacuum insulating layer, the vacuum insulating layers 7 on both sides of the thrust support structure can be evacuated simultaneously using a common vacuum pump, making vacuum management easy.

[0043] As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present disclosure. Therefore, such additions, modifications, and deletions are also included in the scope of the present disclosure.

Claims

1. A double pipe for transporting cryogenic fluid comprising: an inner pipe for passing a cryogenic fluid; and an outer pipe covering the outside of the inner pipe and forming an insulating layer between the inner pipe and the outer pipe, wherein a thrust support structure is provided between the inner pipe and the outer pipe, the thrust support structure comprising: a first support member fixed to the outer peripheral surface of the inner pipe and having a first support surface facing a first direction along the axis of the double pipe; a second support member fixed to the inner peripheral surface of the outer pipe and having a second support surface facing a second direction opposite to the first direction; and a first intermediate support member made of an insulating material and disposed between the first support surface of the first support member and the second support surface of the second support member.

2. A double pipe for transporting a cryogenic fluid according to claim 1, wherein the inner pipe is provided with an expandable portion that absorbs changes in the axial length of the inner pipe.

3. A double piping for transporting cryogenic fluids according to claim 1 or 2, wherein the thrust support structure comprises: a third support member fixed to the outer peripheral surface of the inner pipe and having a third support surface facing the second direction; a fourth support member fixed to the inner peripheral surface of the outer pipe and having a fourth support surface facing the first direction; and a second intermediate support member made of a thermal insulating material and arranged between the third support surface of the third support member and the fourth support surface of the fourth support member.

4. A double pipe for transporting cryogenic fluids according to claim 3, wherein the first support member and the third support member of the thrust support structure are integrally formed to constitute a common intermediate support member.

5. A double pipe for transporting a cryogenic fluid according to claim 1 or 2, wherein the first support member and the second support member overlap in the radial direction when viewed in the axial direction.

6. A double pipe for transporting a cryogenic fluid according to claim 1 or 2, wherein the thrust support structure has a communication gap for communicating the insulating layers through the thrust support structure.

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