JP2019173834A - Internal piping structure of vacuum heat insulation pipe - Google Patents

Abstract

The present invention relates to an internal piping structure of a vacuum heat-insulating pipe capable of absorbing heat shrinkage of an internal pipe through which a cryogenic fluid flows and reducing the size thereof. An internal piping structure of a vacuum insulation pipe according to the present invention is provided with an internal pipe in which a cryogenic fluid flows and which is installed inside a vacuum outer pipe held in vacuum, and a pipe constituting the internal pipe. A bellows 11 provided between the pipe 7 and the pipe 9 for absorbing thermal shrinkage of the internal pipe 5 generated when the cryogenic fluid flows through the internal pipe 5; And a thrust receiving member 13 for receiving the thrust generated in the internal pipe 5 by the pipe 7. The pipe 7 has an enlarged diameter portion 7 a having an enlarged diameter at an end portion thereof, and the pipe 9 has an end portion thereof. Are inserted into the enlarged diameter portion 7a of the tube 7 with a predetermined gap therebetween, and the bellows 11 are disposed along the outer peripheral surface of the end of the tube 9 inserted into the enlarged diameter portion 7a. Is connected to the tube end 9a of the tube 9 and the tip 7b of the enlarged diameter portion 7a. Is shall. [Selection diagram] Fig. 1

Description

The present invention relates to an internal piping structure of a vacuum heat insulating pipe, and more particularly to an internal piping structure of a vacuum heat insulating pipe that absorbs heat shrinkage when a cryogenic fluid flows in the internal pipe.
In the present specification, the internal piping structure of the vacuum heat insulating piping may be simply referred to as “internal piping structure”. In the present invention, examples of the cryogenic fluid include liquid nitrogen and liquid helium, and the kind of the cryogenic fluid is not particularly limited.

Conventionally, in a vacuum insulation pipe that circulates cryogenic fluid such as liquid nitrogen through an internal pipe installed inside a vacuum outer pipe that is held in a vacuum, the internal pipe receives heat from the cryogenic fluid and heat shrinks. In order to avoid stress concentration due to the thermal contraction, an internal piping structure including a cylindrical bellows that absorbs the thermal contraction is used.
For example, the internal pipe structure 31 of the vacuum heat insulating pipe shown in FIG. 4 includes a pipe 37 and a pipe 39 that are installed inside the vacuum outer pipe 33 and through which a low-temperature fluid flows, and a pipe 37 and a pipe 39. A bellows 41 that is connected and expands and contracts in the axial direction is provided, and the bellows 41 extends the same length as the heat shrinkage of the tube 37 and the tube 39 to absorb the heat shrinkage.

  Further, in the internal piping structure 31, when the cryogenic fluid is circulated through the pipes 37 and 39, the internal pressures of the pipes 37 and 39 are higher than the inside of the vacuum outer pipe 33 held in a vacuum. As shown in FIG. 4, the bellows 41 generates a thrust toward the outside in the axial direction. Therefore, in order to suppress the expansion of the bellows 41 due to the thrust, it is necessary to receive the thrust.

  Therefore, in the internal piping structure 31 shown in FIG. 4, as the thrust receiving member 43 that receives the thrust, a support portion 45 and a support portion 47 erected on the outer peripheral surfaces of the pipe 37 and the pipe 39, A tie rod bolt 49 that connects the support portion 47 is provided.

  As another conventional example of the internal piping structure of the vacuum heat insulating piping, there is an internal piping structure 61 as shown in FIG. Similar to the internal piping structure 31 shown in FIG. 4, the internal piping structure 61 absorbs heat shrinkage by the bellows 41 connecting the pipe 37 and the pipe 39, but the internal piping structure 61 is shown in FIG. 5. As described above, a thrust receiving member 67 including an inner stopper 63 provided on the outer peripheral surface of each of the tube 37 and the tube 39 and an outer stopper 65 provided on the inner peripheral surface of the vacuum outer tube 33 is provided.

  In the internal piping structure 61, when a thrust acts on the bellows 41 and the pipe 37 and the pipe 39 move to the outside in the axial direction, the inner stopper 63 comes into contact with the outer stopper 65 to receive the thrust. Moreover, since the internal piping structure 61 does not install a tie rod bolt on the outer side in the circumferential direction than the bellows 41, the diameter of the vacuum outer tube 33 can be reduced.

  As a structure having the same structure as the internal piping structure 61 shown in FIG. 5, Patent Document 1 discloses a cryogenic pipe provided with a bellows that absorbs contraction of a pipe through which a cryogenic fluid flows. The cryogenic pipe disclosed in Patent Document 1 is provided with a protrusion that projects from the outer periphery of the pipe and a shrinkage restricting portion that includes restraining metal fittings provided on both sides of the protrusion. The portion stops the movement of the protrusion by the restraining metal fitting so that the bellows does not extend excessively when the pipe through which the cryogenic fluid flows contracts and the bellows extends.

Japanese Utility Model Publication No. 58-9164

  In the internal piping structure 31 shown in FIG. 4, the bellows 41 forms a flow path F through which the cryogenic fluid flows together with the internal piping 35, but the cryogenic fluid contacts the inner surface of the uneven bellows 41. Pressure loss increases. Therefore, in order to reduce the pressure loss when the cryogenic fluid passes through the bellows 41, a bellows 41 having a diameter larger than that of the pipe 37 and the pipe 39 is used. In such a case, the tie rod bolt 49 is disposed further outward in the circumferential direction than the bellows 41, and the diameter of the vacuum outer tube 33 is further increased.

  Further, as described above, the inner piping structure 61 shown in FIG. 5 is capable of reducing the diameter of the vacuum outer tube, but the inner stopper 63 is formed on the outer side in the axial direction by the thrust generated by circulating the cryogenic fluid. If it moves to and contacts the outer stopper 65, there is a problem that heat input from the vacuum outer tube 33 to the tube 37 and the tube 39 increases due to solid heat conduction at the contacted portion. Such heat input to the internal pipe due to the solid heat conduction occurs between the protrusion of the shrinkage restricting portion provided on the cryogenic pipe and the restraining fitting even in the cryogenic pipe disclosed in Patent Document 1. It is considered a thing.

  The present invention has been made to solve the above-described problems, and has an internal piping structure of a vacuum heat insulating pipe capable of reducing the diameter of a vacuum outer pipe in which the internal pipe and the bellows are installed. The purpose is to provide. Another object of the present invention is to suppress heat input from the vacuum outer pipe to the internal pipe in addition to the object.

(1) The internal piping structure of the vacuum heat insulating piping according to the present invention includes an internal piping that is installed inside a vacuum outer tube held in a vacuum and through which a cryogenic fluid flows, and a tube and a tube constituting the internal piping. It is provided between the bellows that absorbs the thermal contraction of the internal pipe that occurs when the cryogenic fluid flows through the internal pipe and the internal pressure that is generated when the cryogenic fluid flows through the internal pipe. A thrust receiving member for receiving a thrust, wherein one pipe of the internal pipe has a diameter-expanded portion on the end side, and the other pipe of the internal pipe has an end thereof And a bellows is disposed along the outer peripheral surface of the end of the other tube inserted into the expanded diameter portion, and the bellows is inserted into the expanded diameter portion of the one tube. Each end is connected to the tube end of the other tube and the tip of the enlarged diameter portion. And it is characterized in that is.

(2) In the device according to (1), the thrust receiving member includes a support portion erected on an outer peripheral surface of the other pipe inserted into the expanded diameter portion, the support portion and the expanded diameter. It consists of a connection member that connects the parts.

(3) In the device according to (1), the thrust receiving member includes a support portion erected on an outer peripheral surface of each of the one tube and the other tube, with the diameter-enlarged portion interposed therebetween, and the support It consists of the connection member which connects parts, and is characterized by the above-mentioned.

(4) In the device according to any one of (1) to (3), the connecting member is made of an Invar alloy.

(5) In any of the above (1) to (4), the connecting member is a tubular member.

(6) In the device according to any one of (1) to (5), the gap provided between the one tube and the other tube is set to be able to guide the contraction of the bellows. It is characterized by that.

  In the present invention, an internal pipe that is installed inside a vacuum outer pipe held in a vacuum and through which a cryogenic fluid flows, and a pipe that constitutes the internal pipe are provided between the pipe and a cryogenic pipe. A bellows that absorbs thermal contraction of the internal pipe that occurs when the fluid flows, and a thrust receiving member that receives the thrust generated in the internal pipe by the internal pressure when the cryogenic fluid flows through the internal pipe The one pipe of the internal pipe has a diameter-expanded part that is enlarged on the end side, and the other pipe of the internal pipe has the end part at the diameter-expanded part of the one pipe. The bellows is disposed along the outer peripheral surface of the end of the other tube inserted into the enlarged diameter portion, and each end of the bellows is inserted into the tube of the other tube. By being connected to the end and the tip of the enlarged diameter portion, The diameter of the vacuum envelope can be miniaturized by reducing the diameter of the rose. Furthermore, in the present invention, heat input from the vacuum outer pipe to the internal pipe can be suppressed by providing the thrust receiving member in the internal pipe.

It is a figure which shows the outline of the internal piping structure of the vacuum heat insulation piping which concerns on Embodiment 1 of this invention. It is a figure explaining the principle which absorbs the thermal contraction of the internal piping cooled with the low temperature fluid by the bellows in the internal piping structure of the vacuum heat insulation piping which concerns on Embodiment 1 of this invention. It is a figure which shows the outline of the internal piping structure of the vacuum heat insulation piping which concerns on Embodiment 2 of this invention. It is a figure explaining an example of the internal piping structure of the conventional vacuum heat insulation piping. It is a figure explaining the other example of the internal piping structure of the conventional vacuum heat insulation piping.

The internal piping structure of the vacuum heat insulating piping according to Embodiments 1 and 2 of the present invention will be described below.
In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.
Further, the dimensions and other specific numerical values shown in the first and second embodiments are merely examples for facilitating understanding of the present invention, and do not limit the present invention.

<Embodiment 1>
As shown in FIG. 1, the internal piping structure 1 of the vacuum heat insulating piping according to Embodiment 1 includes an internal piping 5 that is installed inside a vacuum outer tube 3 and through which a cryogenic fluid flows, and an internal piping 5. A bellows 11 provided between the one pipe 7 and the other pipe 9 and a thrust receiving member 13 that receives the thrust generated in the internal pipe 5 by the internal pressure when the cryogenic fluid flows through the internal pipe 5. The thrust receiving member 13 includes a support portion 15 and a connection member 17.
Each configuration will be described below.

  The inside of the vacuum outer tube 3 is held in a substantially vacuum (˜−0.1013 MPaG), and insulates the internal pipe 5 installed inside by vacuum insulation. In the vacuum outer pipe 3, a laminated heat insulating material (not shown) may be installed outside the internal pipe 5.

The internal pipe 5 is installed inside the vacuum outer pipe 3 and becomes a flow path F through which a cryogenic fluid flows. In FIG. 1, the internal pipe 5 includes two pipes 7 and 9.
One tube 7 has a diameter-expanded portion 7a that is expanded on the end side.
The other tube 9 is inserted into the enlarged diameter portion 7 a of the tube 7 with a predetermined gap at its end.

  Further, the internal pipe 5 forms a double pipe structure with the vacuum outer pipe 3, and it is necessary to fix the internal pipe 5 inside the vacuum outer pipe 3 due to the structure. Therefore, in FIG. 1, the pipe 7 that is the internal pipe 5 is fixed by the inner pipe support 19.

  The bellows 11 is disposed in the gap along the outer peripheral surface of the tube 9 inserted in the enlarged diameter portion 7a, and each end thereof is connected to the tip 7b of the enlarged diameter portion 7a and the tube end 9a of the tube 9. Has been.

  The thrust receiving member 13 includes a support portion 15 erected on the outer peripheral surface of the tube 9 inserted into the enlarged diameter portion 7a, and a connection member 17 that connects the support portion 15 and the distal end 7b of the enlarged diameter portion 7a. In this case, the thrust (see FIG. 2) due to the internal pressure when the cryogenic fluid flows through the pipe 7 and the pipe 9 is received.

  As the connection member 17, a tie rod bolt can be used as in the conventional internal piping structure 31 (FIG. 4), and both ends of the tie rod bolt may be joined to the enlarged diameter portion 7 a and the support portion 15 with screws or the like.

  In the first embodiment, the connecting member 17 is preferably made of an Invar alloy. By using the Invar alloy, the connecting member 17 is cooled by the cryogenic fluid flowing through the internal pipe 5 and does not thermally contract, so the change in the span length between the enlarged diameter portion 7a and the support portion 15 can be prevented more reliably. it can.

The thrust generated by the internal pressure when the cryogenic fluid flows through the pipes 7 and 9 is the internal pressure generated in the internal pipe 5 due to the supply of the cryogenic fluid and the pressure inside the vacuum outer pipe 3 reduced to a substantially vacuum. It means the load which goes to the axial direction outside centering on the bellows 11 by the pressure difference with these.
For example, when a cryogenic fluid is supplied to an internal pipe with a nominal diameter of 100A, the thrust is 1000N when the inside of the vacuum outer pipe is vacuum (-0.1013MPaG) and the internal pressure of the internal pipe is atmospheric (0MPaG). When the internal pressure of the internal pipe is 1.9 MPaG, it is estimated as 20000 N (see FIGS. 4 and 5).

Next, the effect by the internal piping structure 1 of the vacuum heat insulation piping which concerns on this Embodiment 1 is demonstrated.
In the internal pipe structure 1 of the vacuum heat insulating pipe according to the first embodiment, the gap between the tip 7b of the pipe 7 and the pipe end 9a of the pipe 9 with respect to the flow path F of the internal pipe 5 through which the cryogenic fluid flows. Is a folded structure in which the bellows 11 are folded back through the bellows 11, and unlike the conventional internal piping structure 31 (see FIG. 4), the bellows 11 does not face the flow path F. Therefore, it is not necessary to consider the pressure loss in the bellows 11, the diameter of the bellows 11 can be reduced to the outer diameter of the internal pipe 5, and the size can be reduced as compared with the conventional internal pipe structure 31. .

  Moreover, in the internal piping structure 1 of the vacuum heat insulating pipe according to the first embodiment, one end of the connection member 29 is connected to the tip 7b of the enlarged diameter part 7a without providing a support part on the outer peripheral surface of the pipe 7. ing. Therefore, compared with the internal piping structure 1 according to the second embodiment described later, the connecting member 17 can be installed close to the outer peripheral surface of the internal piping 5, and the diameter of the vacuum outer tube 3 can be further reduced. Can do.

For example, as shown in FIG. 2, when the nominal diameter of the internal pipe 5 (the pipe 7 and the pipe 9) is 100A, and the bellows 11 installed on the outer peripheral surface of the pipe 9 has a nominal diameter of 125A, the bellows 11 The outer diameter is d ₁ = 168 mm. In order to install the bellows 11 in the gap between the enlarged diameter portion 7a and the tube 9, the outer diameter of the enlarged diameter portion 7a may be set to about 189 mm. Since the outer diameter d ₁ (FIG. 1) of the connecting member 17 can be made substantially equal to the outer diameter of the enlarged diameter portion 7a, the vacuum outer tube 3 having a nominal diameter of 200A (od216.3 mm) is used. be able to.

  Further, the internal piping structure 1 includes a supporting portion 15 erected on the outer peripheral surface of the tube 9 as a thrust receiving member 13 that receives the thrust generated in the tubes 7 and 9, and a diameter increasing portion of the supporting portion 15 and the tube 7. A connecting member 17 is provided to connect 7a. Therefore, unlike the conventional internal piping structure 61 (FIG. 5), the internal piping structure 1 does not cause solid heat conduction between the vacuum outer tube 3 and the internal piping 5.

  As described above, in the internal piping structure 1 of the vacuum heat insulating piping according to the first embodiment, the thermal contraction generated in the internal piping 5 when the cryogenic fluid is circulated is absorbed by the bellows 11 and from the vacuum outer tube 3. The diameter of the vacuum outer tube 3 can be reduced without increasing the heat input to the internal piping 5.

  In the internal piping structure 1, when a cryogenic fluid flows through the internal piping 5, the pipe 7 and the pipe 9 are thermally contracted in directions indicated by arrows in FIG. 2, respectively. At this time, since the connection member 17 is connected between the tip 7b of the enlarged diameter portion 7a and the support portion 15 (see FIG. 2), the bellows 11 is not affected by the thermal contraction of the tube 7, and the tube 7 It shrinks only by heat shrinkage.

Therefore, in the internal piping structure 1, the span length between the tip 9a of the tube 9 and the support portion 15 takes heat shrinkage into account, and the amount of change in the span length is the amount absorbed by the bellows 11. On the other hand, between the tip 7b of the enlarged diameter portion 7a and the inner tube support 19 (length L ₁ ), the heat shrinkage is reduced by heat shrinkage. It is absorbed by the clearance or bending of the tube 9.

  Therefore, in the internal pipe 5 having a bent portion like the pipe 7 shown in FIG. 1, the position where the bellows 11 is provided between the pipe 7 and the pipe 9 in order to reduce the range in which the heat shrinkage is not absorbed. It is desirable to be as close to the bent portion of the tube 7 as possible.

  However, the internal piping structure according to the first embodiment is not limited to the one having the elbow as shown in FIG. 1 in the vicinity of the enlarged diameter portion 7a for both the one pipe 7 and the other pipe 9. Both the pipe 7 and the pipe 9 may have a straight pipe shape.

  When the internal piping structure according to the first embodiment includes an internal pipe composed of straight pipes and pipes, the length of the internal pipe can be increased by connecting a plurality of straight pipes. it can.

  In addition, about the material of the connection member 17, although it was what used the Invar alloy in said description, what is necessary is just a member of the low thermal expansion coefficient with a small thermal contraction even if it cools. The same).

  Moreover, about the shape of the connection member 17, it is not restricted to a rod-shaped member like a tie rod bolt, A tubular member may be sufficient, and there is no limitation in particular about the shape. However, it is preferable that the connecting member 17 be a tubular member because it is possible to prevent deflection in the axial direction (the same applies to the second embodiment described later).

  In the above description, the connecting member 17 is connected to the tip 7b of the enlarged diameter portion 7a. However, the connection position of the connecting member 17 and the enlarged diameter portion 7a is not limited to the distal end 7b. It may be an arbitrary position of 7a.

  Further, the gap provided between the tube 7 and the tube 9 in the enlarged diameter portion 7a is such that the bellows 11 can be contracted, and the bellows 11 is formed by the outer peripheral surface of the tube 9 and the inner peripheral surface of the enlarged diameter portion 7a. It is more preferable that the gap is set so that the shrinkage can be guided (the same applies to the second embodiment described later).

  In the internal piping structure 1 according to the first embodiment, the direction in which the cryogenic fluid flows may be either the direction from the pipe 9 to the pipe 7 or the direction from the pipe 7 to the pipe 9. From the viewpoint of pressure loss, the direction from the tube 9 inserted into the enlarged diameter portion 7a to the tube 7 is preferable (the same applies to the second embodiment described later).

<Embodiment 2>
As shown in FIG. 3, the internal piping structure 21 of the vacuum heat insulating piping according to the second embodiment includes an internal piping 5 that is installed inside the vacuum outer tube 3 and through which a cryogenic fluid flows, and an internal piping 5. A bellows 11 provided between one pipe 7 and the other pipe 9 and a thrust receiving member 23 that receives the thrust generated in the internal pipe 5 by the internal pressure when the cryogenic fluid flows through the internal pipe 5. The thrust receiving member 23 includes a support portion 25, a support portion 27, and a connection member 29.
Here, since the pipe 7, the pipe 9, and the bellows 11 in the internal piping structure 21 are the same as those in the internal piping structure 1 according to the first embodiment described above, the thrust receiving member 23 will be described below.

  The thrust receiving member 23 includes a support portion 25 erected on the outer peripheral surface of the tube 7, a support portion 27 erected on the outer peripheral surface of the tube 9, and a connection member 29 that connects the support portion 25 and the support portion 27. And receives the thrust (see FIG. 2) due to the internal pressure when the cryogenic fluid flows through the pipe 7 and the pipe 9.

The support part 25 and the support part 27 are erected on the outer peripheral surfaces of the pipe 7 and the pipe 9 with the diameter-expanded part 7 a interposed therebetween in the axial direction of the internal pipe 5.
The connection member 29 connects the support part 25 and the support part 27 and receives thrust generated by internal pressure when the cryogenic fluid flows through the pipe 7 and the pipe 9.

  As the connection member 29, for example, a tie rod bolt can be used, and both ends of the tie rod bolt may be joined to the support portion 25 and the support portion 27 with screws or the like.

  In the second embodiment, the connecting member 29 is preferably made of an Invar alloy. By using the Invar alloy, the connection member 29 is cooled by the cryogenic fluid flowing through the internal pipe 5 and does not thermally contract, so that the span length between the support portion 25 and the support portion 27 can be prevented more reliably. it can.

  Next, the effect by the internal piping structure 21 which concerns on this Embodiment 2 is demonstrated by contrasting with the conventional internal piping structure 31 (FIG. 4) mentioned above.

  The conventional internal piping structure 31 absorbs the thermal contraction of the pipes 37 and 39 by the extension of the bellows 41, but when a cryogenic fluid flows through the pipes 37 and 39, the tie rod bolt 49 passes through the support portions 45 and 47. It cools itself. In general, since the tie rod bolt 49 is made of stainless steel, it shrinks when the tie rod bolt 49 is cooled. Therefore, it is necessary to take measures to prevent stress concentration on the internal pipe 35 due to the shrinkage. .

  Specifically, the support portions 45 and 47 are made as long as possible to secure a temperature difference between the root portion attached to the outer peripheral surface of the internal pipe 35 and the tip portion to which the tie rod bolt 49 is connected. It is. In addition to this, a heat insulating material 51 is installed in order to limit the heat conduction between the support portions 45 and 47 and the tie rod bolt 49, and heat transfer between the outer peripheral surface of the internal pipe 35 and the tie rod bolt 49 is performed. In order to suppress, a laminated heat insulating material may be installed on the outer peripheral surface side of the internal pipe 35.

  However, it is necessary to increase the diameter of the vacuum outer tube 33 that houses the internal pipe 35 connected by the tie rod bolt 49 by elongating the support portions 45 and 47. For example, in the internal piping structure 31 shown in FIG. 4, for example, the outer diameter including the tie rod bolts 49 provided via the support portions 45 and 47 with respect to the internal piping 35 having a nominal diameter of 100A is about 270 mm, and the vacuum The outer tube 33 having a nominal diameter of 300A is selected, and the diameter of the vacuum outer tube is larger by the amount of the tie rod bolt.

  In addition, it is not preferable to lengthen the support portions 45 and 47 because the bending moment at the support portions 45 and 47 when the tie rod bolt 49 is thermally contracted increases.

  Therefore, in order to reduce the size of the vacuum outer tube 33 without making the support portions 45 and 47 erected on the internal pipe 35 longer than necessary, the tie rod bolt 49 should be made of a material having a low coefficient of thermal expansion. Thus, the tie rod bolt 49 can be installed close to the internal pipe 35, and the vacuum outer pipe can be downsized.

  However, in the internal piping structure 31, the flow path F through which the cryogenic fluid flows is formed by the pipe 37 and the pipe 39 and the bellows 41, and the cryogenic fluid is in contact with the inner surface of the bellows 41 as described above. Pressure loss will increase. Therefore, in order to make the influence of the pressure loss in the bellows 41 almost equal to that of the pipes 37 and 39 which are straight pipes, the bellows 41 having a diameter larger than that of the pipes 37 and 39 is used.

  For example, as shown in FIG. 4, a bellows 41 having a nominal diameter of 125A is illustrated for an internal pipe having a nominal diameter of 100A. Therefore, even if a member having a small coefficient of thermal expansion is used for the tie rod bolt 49 as the connecting member, the installation position of the tie rod bolt 49 (the height of the support portions 45 and 47) depends on the diameter of the bellows 41. Therefore, the range in which the vacuum outer tube 33 can be reduced is limited.

On the other hand, in the internal piping structure 21 according to the second embodiment, the bellows 11 is disposed in the gap between the pipe 7 and the pipe 9 along the outer peripheral surface of the end portion of the pipe 9, so that the cryogenic temperature is low. It does not face the fluid flow path F. Therefore, it is not necessary to consider the pressure loss in the bellows 11, and the diameter of the bellows 11 can be reduced to about the outer diameter of the internal pipe 5. As a result, the outer diameter d ₂ (FIG. 3) of the connecting member 17 can be made approximately equal to the outer diameter of the enlarged diameter portion 7 a, and can be made smaller than the conventional internal piping structure 31.

  As described above, also in the internal piping structure 21 of the vacuum heat insulating piping according to the second embodiment, the thermal contraction generated in the internal piping 5 when the cryogenic fluid is circulated is absorbed by the bellows 11 and the diameter of the vacuum outer tube. Can be reduced in size.

  In the internal piping structure 21, the position where the pipe 7 and the pipe 9 are connected via the enlarged diameter part 7 a and the bellows 11 is between the support part 45 and the support part 47 where both ends of the connection member 17 are fixed. The bellows 11 can absorb the thermal contraction of the internal pipe 5 between the support portions 45 and 47 even if the position where the pipe 7 and the pipe 9 are connected is changed.

  Further, the support portions 25 and 27 may be ones in which arm-shaped members are erected on the outer peripheral surface, or disk-shaped ones such as flanges are erected on the outer peripheral surface.

Note that the tube 7 shown in FIG. 3 has a shape that has a bent portion (elbow) that rises substantially vertically and is bent in the horizontal direction on the enlarged diameter portion 7a side. In this case, the heat shrinkage between the support portion 25 and the support portion 27 is absorbed by the bellows 11, but the heat shrinkage of the bent portion (range L _{2 in} FIG. 3) in the tube 7 supports the tube 7. It is absorbed by the clearance between the inner tube support 19 and the vacuum outer tube 3 or by bending at the bent portion of the tube 7.

  However, the present invention depends on whether each of the one pipe 7 and the other pipe 9 that are the internal pipes 5 has an elbow as shown in FIG. 3 in the vicinity of the enlarged diameter portion 7a. However, both the pipe 7 and the pipe 9 may have a straight pipe shape. And when lengthening a full length using straight pipe-shaped internal piping, what is necessary is just to connect two or more internal piping structures which concern on this Embodiment 2. FIG.

DESCRIPTION OF SYMBOLS 1 Internal piping structure of vacuum heat insulation piping 3 Vacuum outer pipe 5 Internal piping 7 Pipe 7a Expanding part 7b Tip 9 Pipe 9a Pipe end 11 Bellows 13 Thrust receiving member 15 Support part 17 Connection member 19 Inner pipe support 21 Inside of vacuum insulation pipe Piping structure 23 Thrust receiving member 25, 27 Support part 29 Connection member 31 Internal piping structure of vacuum heat insulating piping (conventional example)
33 Vacuum outer pipe 35 Internal pipe 37, 39 Pipe 41 Bellows 43 Thrust receiving member 45, 47 Support part 49 Tie rod bolt 51 Heat insulation 61 Internal pipe structure of vacuum heat insulation pipe (conventional example)
63 Inner stopper 65 Outer stopper 67 Thrust receiving member

Claims (6)

An internal pipe that is installed inside a vacuum outer pipe held in a vacuum and through which a cryogenic fluid flows, and a pipe that constitutes the internal pipe is provided between the pipes, and when the cryogenic fluid flows through the internal pipe An internal pipe of a vacuum heat insulating pipe comprising a bellows that absorbs heat shrinkage of the internal pipe that occurs in the internal pipe and a thrust receiving member that receives a thrust generated in the internal pipe by an internal pressure when a cryogenic fluid flows through the internal pipe Structure,
One pipe of the internal pipe has a diameter-expanded portion that is diameter-expanded on the end side,
The other pipe of the internal pipe has its end inserted into the enlarged diameter part of the one pipe with a predetermined gap,
The bellows is disposed along the outer peripheral surface of the end portion of the other tube inserted into the enlarged diameter portion, and each end portion thereof is at the tube end of the other tube and the distal end of the enlarged diameter portion. Internal piping structure of vacuum insulation piping characterized by being connected.   The thrust receiving member includes a support portion erected on the outer peripheral surface of the other pipe inserted into the enlarged diameter portion, and a connection member that connects the support portion and the enlarged diameter portion. The internal piping structure of the vacuum heat insulating piping according to claim 1, wherein:   The thrust receiving member is provided with a support portion erected on the outer peripheral surface of each of the one tube and the other tube with the enlarged diameter portion interposed therebetween, and a connection member that connects the support portions to each other. The internal piping structure of the vacuum heat insulating piping according to claim 1, wherein: The internal connection structure of the vacuum heat insulation pipe according to any one of claims 1 to 3, wherein the connecting member is made of an Invar alloy.   The internal piping structure of the vacuum heat insulating piping according to any one of claims 1 to 4, wherein the connecting member is a tubular member.   6. The gap according to claim 1, wherein the gap provided between the one tube and the other tube is set so as to be able to guide the contraction of the bellows. Internal piping structure of vacuum insulation piping.