JPH0248798B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention is applicable to cryogenic fluids near absolute zero, e.g.
This article relates to the structure of the connection in a cryogenic transport pipe for transporting cryogenic helium gas at 4.5K. This invention is particularly applicable to cryogenic fluids that are primarily transported, and cryogenic fluids that are cryogenic but have a higher temperature than the fluid that is primarily transported, and that are allowed to have a slight temperature rise during transportation. The present invention relates to a cryogenic transport pipe connection structure that can prevent the temperature of the cryogenic fluid, which is the main object to be transported, from rising when simultaneously transporting the cryogenic fluid.

Conventional technology In recent years, technology that utilizes extremely low temperatures close to absolute zero has developed, and for example, various devices and equipment that utilize superconducting phenomena are being developed, as well as electron microscopes and other various experimental and measuring instruments that utilize extremely low temperatures. demand is increasing. As a result, there is an increasing demand for transport pipes for transporting cryogenic fluids such as cryogenic helium gas and liquid helium as refrigerants to these devices and facilities.

By the way, in such cryogenic fluid transport pipes, in order to prevent external high-temperature heat from entering and increasing the temperature of the transport fluid, the transport pipe is generally made to have at least a double structure, with a layer inside the inner pipe. A cryogenic fluid is passed through the inner tube and the outer tube to provide vacuum insulation between the inner tube and the outer tube. Such a transport pipe inevitably has a connection part, and at that connection part, the inner pipe must be supported in some way from the outer pipe side, and the space between the inner pipe and the outer pipe ( Since the vacuum insulation part) must be closed, the vacuum insulation between the outer tube and the inner tube has to be interrupted, and the insulation effect is therefore reduced at that connection, allowing heat to enter from the outside. The temperature of the cryogenic fluid in the inner tube tends to rise. Here, if the transportation fluid is a cryogenic liquid such as liquid helium, the problem of heat intrusion from the outside at the connection part is not so big because of its latent heat, and even if the transport fluid is a cryogenic gas such as helium gas, the flow rate is The bigger it is, the less of a problem it becomes. However, when the flow rate of cryogenic gas such as helium gas is small, heat intrusion from the outside at the connection becomes a major problem.

The above problem will be explained in more detail.
FIG. 1 shows an example of a conventional general cryogenic fluid transport pipe connection part, and a pair of mutually connected cryogenic fluid transport pipes 1A and 1B each have a cryogenic fluid 2 flowing inside them. The inner tubes 3A, 3B are housed coaxially in the large diameter outer tubes 4A, 4B, and the space between the inner tubes 3A, 3B and the outer tubes 4A, 4B is formed into a vacuum insulation part 5A, 5B. The structure is as follows. Both transport pipes 1A and 1B have flange portions 6 for connecting them with bolts or the like.
A, 6B are formed, one of the transport pipes 1A has a convex male part 7 extending from the position of the flange part 6A, and the other transport pipe 1B has a flange part 6B.
A concave female portion 8 is formed that retracts inward from the position. In the male part 7, an inner pipe 3A is surrounded by a male outer pipe 9 that is continuous with an outer pipe 4A of the transport pipe main body part, and the space between the inner pipe 3A and the male outer pipe 9 is vacuum-insulated. There is. Also, in the female part 8, the inner peripheral wall 1
0 and the outer tube 4B are vacuum insulated.

In the connection section of such a conventional cryogenic fluid transport pipe, the length of the male outer tube 9 (the inner circumferential wall 1 of the female section 8)
The portion of length 0) l becomes the heat infiltration path from the outside, but by increasing this length l, the heat transfer distance from the outside to the inner tubes 3A and 3B is increased. This is intended to increase the heat transfer loss between them and prevent the temperature rise of the cryogenic fluid that drips inside the inner tubes 3A and 3B, but simply increasing the heat transfer distance in this way does not allow the If the fluid is a gas and its flow rate is small, the inner tube 3
It is difficult to prevent the temperature of the cryogenic fluid flowing through A and 3B from rising, and for example, the temperature of helium gas at 4.5K may rise to about 6K.

By the way, depending on devices and equipment that utilize cryogenic fluids, there may be cases where it is desired to transport cryogenic fluids having different temperatures. For example, in addition to the fluid used as the original cryogenic medium to obtain the desired cryogenic temperature, the cold storage medium used to keep the surroundings of the cryogenic equipment cold may also be transported at the same time. The temperature may be slightly higher than that of the cryogenic medium. In addition, in order to reuse the exhaust gas from the target cryogenic equipment, a transport route is often provided to supply and transport the cryogenic fluid as a cooling medium to the equipment and return the exhaust gas from the equipment. Normally, the gas is at a somewhat higher temperature than the fluid on the supply side. If such cryogenic fluids having different temperatures are to be transported through completely different pipe lines, the piping becomes complicated, the piping work becomes complicated, and maintenance becomes troublesome. Therefore, recently, transport pipes have been developed that simultaneously transport cryogenic fluids at different temperatures using a single transport pipe. An example of the vicinity of the connection part of the transport pipe is shown in FIG.

In FIG. 2, the flow paths for the cryogenic fluid in the transport pipes 20A and 20B are the inner flow paths 21 and 21, respectively.
A double flow path is formed with the inner flow path 21 and the outer flow path 22 coaxially surrounding the inner flow path 21.
A space between the tube wall 23 and the tube wall 24 on the inner surface of the outer flow path is hollow, and the hollow portion is used as a vacuum heat insulating section 25. Further, a space between the tube wall 26 on the outer surface of the outer flow path 22 and the transport tube outer wall 27 is also hollow, and the hollow portion is used as a vacuum heat insulating section 28 . In such a connection part of the transport pipe, the male transport pipe 2
An annular connecting piece 29 is fixed to the tip of the outer tube wall 26 of the outer flow path 22 at 0A, and the connecting piece 29
O made of an elastic material with heat insulating properties such as Teflon
The ring 30 is retained and the outer channel 22
An annular connecting piece 31 is fixed to the tip of the inner tube wall 24 and the tube wall 23 of the inner flow path 21, and the O-ring 3 made of Teflon or the like is attached to the connecting piece 31 as described above.
2 is retained. The connecting pieces 29 and 31 of the male transport pipe 20A are connected to the ends of the inner channel 21 and the outer channel 2 of the female transport pipe 20B, respectively.
The O-rings 30, 3 are fitted into the ends of the O-rings 30, 3
2 seals each flow path.

When transporting cryogenic fluids at different temperatures using the cryogenic fluid transport pipe shown in FIG.
Typically, a relatively hot cryogenic fluid flows through the outer channel 22. However, in this case, at the connection between the transport pipes 20A and 20B, the inner flow path 2
1 and the outer flow path 22 is achieved only by the O-ring 30 made of Teflon or the like.
The temperature difference between the fluid flowing through the inner flow path 21 and the fluid flowing through the outer flow path 22 is large, and the inner flow path 21
When the fluid flowing through the inner flow path 21 is gas at a small flow rate, there is a problem that the heat of the fluid flowing through the outer flow path 22 easily enters the inner flow path and increases the temperature of the fluid flowing through the inner flow path 21. .

In the conventional device shown in FIG.
It is also possible to extend the male side and female side parts of the vacuum insulation part 25 between the two and overlap the male side vacuum insulation part and the female side vacuum insulation part inside and outside, but in this case, A cylindrical part with a free end and a hollow wall (hollow insulation part)
This type of structure causes mechanical strength problems, especially when the axial center positions are not aligned accurately, and excessive force is applied to the overlapped parts when connecting and connecting. The problem arises that it is easily deformed or damaged. This problem becomes more pronounced when three or more channels are formed concentrically to transport three or more types of cryogenic fluids, and therefore, multiple channels are formed concentrically. In this case, in practice, only two channels are formed, and it is difficult to form three or more channels.

That is, as a connection part structure of a cryogenic fluid transport pipe in which three or more concentric flow paths are formed, the one described in JP-A-52-89855 is already known.
In this proposal, a concentric first intermediate flow path is provided outside the central main flow path as a transport pipe, and a second intermediate flow path is provided outside the first intermediate flow path via a vacuum chamber for heat insulation. In addition, at the connection part, regarding the vacuum chamber between the first intermediate flow path and the second intermediate flow path, the male side vacuum chamber and the female side vacuum chamber are formed into a cylindrical shape. By extending the vacuum chamber and overlapping both the inside and outside, the insulation effect is enhanced. However, in the structure proposed in this proposal, where the vacuum chamber is extended into a cylindrical shape and stacked inside and outside, the number of concentric stacks at the connection part increases significantly, as the flow path itself is triple-layered. In particular, if the axial center position does not match accurately, excessive force may be applied during connection, resulting in deformation or damage. Therefore, it is difficult to put the structure proposed above into practical use. It was hot.

Problems to be Solved by the Invention As mentioned above, in conventional cryogenic fluid transport pipes, when attempting to transport multiple types of cryogenic fluids, the general idea is to overlap multiple channels concentrically. However, when transporting cryogenic fluids, unlike when transporting ordinary liquids or gases, it is necessary to consider insulation, so in order to provide a vacuum insulation layer, concentric layers are stacked at the connection. As the number of wall surfaces to be joined has increased significantly, problems such as strength and alignment at the joints cannot be overlooked.

Therefore, the present inventors fundamentally changed the idea from the structure in which a plurality of channels are provided concentrically as described above, and considered a structure in which a plurality of channels are provided in parallel within the same outer tube. However, simply providing a plurality of channels in parallel within the same outer tube cannot avoid the same problems as in the case of a single channel as shown in FIG. In other words, in FIG. 1, a portion of length l of the male outer tube 9 at the connection portion becomes an entry path through which heat infiltrates the inner tubes 3A, 3B from the outside at the connection portion by thermal conduction, and this length l is increased. By doing so, it is possible to reduce heat intrusion at the connection part to some extent, but if the fluid to be heat transported is a cryogenic gas such as helium gas and its flow rate is small, the fluid's It was not possible to sufficiently prevent the temperature rise, and this problem is exactly the same even when a plurality of channels are provided in parallel within the outer tube.

The present invention has been made against the background of the above circumstances, and in order to transport a plurality of types of cryogenic fluids, in a connecting portion of a transport pipe in which a plurality of channels are provided in parallel in the same outer tube, Among the multiple types of cryogenic fluids mentioned above, the connection structure of the cryogenic fluid transport pipe is designed to reliably prevent a temperature rise in the flow path of the cryogenic fluid, which must be most protected from the effects of heat intrusion from the outside. The purpose is to provide the following.

Measures to solve the problem When multiple flow paths are provided in the same outer tube to transport multiple cryogenic fluids, the temperature rise of all cryogenic fluids transported at the same time is generally strictly regulated to the same extent. There is little need to control the temperature rise of the cryogenic fluid that is the coldest among the cryogenic fluids that are transported at the same time, and less stringently regulate the temperature rise of the cryogenic fluid that is relatively hot. There is often no need to regulate the rise. For example, in cryogenic equipment, we simultaneously use cryogenic fluid as a direct refrigerant to directly cool objects to cryogenic temperatures, cryogenic fluid for cold storage around the cryogenic equipment, and exhaust gas returned from the cryogenic equipment. When transporting the former cryogenic fluid as a direct refrigerant, it is necessary to strictly control the temperature rise during transport.
Cryogenic fluid for ambient cooling and return exhaust gas, etc.
Even at extremely low temperatures, there is no need to strictly control temperature rises.

The present inventors skillfully utilized the above-mentioned relationship at the connection part of a cryogenic fluid transport pipe in which multiple flow paths are provided in the same outer tube, and determined the temperature rise at the connection part where it is most important to avoid the temperature rise. They invented a structure that reliably prevents the temperature of cryogenic fluid from rising. In other words, the temperature of the fluid that does not require much temperature rise (relatively high temperature, but compared to the surrounding outside air temperature) is This effectively prevents heat from entering from the outside at the connections, even in the fluid flow paths where temperature rises must be avoided most severely. .

Specifically, in the connection structure of the cryogenic fluid transport pipe of the present invention, a plurality of inner pipes 41, 42, 43 through which cryogenic fluids of different temperatures flow are connected to the same outer pipe 44.
The cryogenic transport tubes 40A, 4 are housed in parallel at intervals and have a vacuum insulation section 45 between the inner tubes and between the inner tube and the outer tube.
A connecting part structure for mutually connecting 0B; The connecting end of one cryogenic transport pipe is fitted into a concave female part 48 formed at the leading end of the other cryogenic transport pipe. A convex male portion 47 is formed, and a portion of the outer wall of the convex male portion from the base of the male portion to the intermediate portion of a predetermined length toward the tip is a transport pipe main body portion. It is composed of a collective outer tube part 49 that is continuous with the outer tube and surrounds the plurality of inner tubes all at once, and a part between the intermediate part and the tip is continuous with the collective outer tube part and surrounds the plurality of inner tubes at once. It is composed of divided outer tube portions 50, 51, and 52 divided corresponding to each inner tube so as to individually surround the plurality of inner tubes, and further includes a distal end surface of each of the different divided outer tube portions. The ends of the inner tubes are opened, respectively, and the transport tube main body portions are connected between the collective outer tube section and the inner tube inside thereof, and between each divided outer tube section and the inner tube inside thereof. Vacuum insulation parts 53 and 54 are continuous to the vacuum insulation part, and on the other hand, the part of the inner wall of the concave female part between the opening end and the intermediate part of the predetermined distance toward the innermost end is: It is composed of a collective inner wall tube part 55 into which the collective outer tube part of the male part is fitted, and the part from the middle part to the innermost end is continuous with the collective inner wall pipe part and is connected to the divided outer tube part of the male part. divided inner wall tube portions 56, 57, 58 into which the portions are individually fitted;
In addition, the corresponding end of the inner tube is opened at the inner end of each divided inner wall tube, and between the female part of the inner wall tube and the outer tube and the divided inner wall tube. Vacuum insulation parts 59 and 60 are connected to the vacuum insulation part of the transport pipe main body part between the part and the outer pipe.
Further, at least in the male part of the male part and the female part, there is a part near the middle part between the inner pipe through which a relatively high temperature cryogenic fluid flows among the plurality of inner pipes and the outer wall of the male part. This is characterized in that the space between the two is connected by a heat transfer piece 61A made of a material with high thermal conductivity.

Function In the connection structure of the cryogenic fluid transport pipe of the present invention, heat from the outside is absorbed from the outer wall of the male part 47 (outer pipe part).
The heat conduction along the inner wall of the female part 48 causes the heat to enter the inside of the female part 48. However, the male part 47 and the female part 4
8, at least in the male part 47, a relatively high-temperature cryogenic fluid among the plurality of inner tubes 41, 42, and 43 (i.e., a cryogenic fluid that does not require very strict regulation of temperature rise) flows. Since the inner tube (for example 42) and the intermediate portion (boundary surface 63) of the outer tube portion of the male portion 47 are directly connected by the heat transfer piece 61A made of a highly thermally conductive material, the male portion The intermediate portion 63 of the outer tube section is cooled by the cryogenic fluid flowing through the inner tube 42 via the heat transfer piece 61A, and has a temperature much closer to the temperature of the cryogenic fluid flowing through the inner tube 42 than the outside temperature. . Therefore, in the portion beyond the intermediate portion 63, that is, in the portions of the divided outer tube portions 50, 51, and 52, the temperature gradient becomes significantly smaller, and heat intrusion from the outside is significantly reduced, causing Connected inner pipe 4
The divided outer tube portions 50, 5 for 1, 42, 43
Temperature rise due to external heat intrusion through 1 and 52 is significantly reduced. In other words, the male part 4 is
7 is bypassed from the intermediate portion 63 of the male portion 47 to the inner tube 42 via the heat transfer piece 61A, and as a result, the divided outer tube portions 50, 5 of the male portion
Therefore, the temperature rise in the remaining inner pipes 41, 43 except for the inner pipe 42 is significantly reduced, and the temperature rise of the cryogenic fluid flowing inside the inner pipes 41, 43 is significantly reduced. can be effectively prevented. Therefore, by circulating the cryogenic fluid whose temperature should most likely not rise through the inner tubes 41 and 43, it is possible to reliably prevent the temperature of the fluid from rising. Note that the inner tube 42 to which the heat transfer piece 61A is connected is as follows.
Although the temperature rises slightly due to heat intrusion from the outside through the heat transfer piece 61A, this point does not occur because the cryogenic fluid that does not need to strictly control the temperature rise is flowing through the inner tube 42 in the first place. There is no particular problem.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 3 and subsequent drawings.

FIG. 3, FIG. 4, and FIG. 5 show the structure of a connecting portion of a cryogenic fluid transport pipe according to an embodiment of the present invention. However, in FIG. 3, inner tubes 41, 42, and 43, which will be described later, are shown arranged on the same plane for ease of understanding, but in reality, inner tubes 41, 43, and
42 and 43 are arranged as shown in FIGS. 4 and 5.

In Figures 3 to 5, transport pipes 40A, 40B
The main body portion includes three inner tubes 41, 42, 43 also made of stainless steel, spaced apart from each other and spaced from the inner wall of the outer tube 44, within an outer tube 44 made of stainless steel, respectively. They are arranged in parallel. These inner tubes 41, 4
Reference numerals 2 and 43 indicate inner pipes through which cryogenic fluids to be transported flow, and in this example, the first inner pipe 41 is the cryogenic fluid that is at the lowest temperature and must be prevented from increasing in temperature, for example. A cryogenic fluid is flowed as a refrigerant to provide the necessary cryogenic temperature to the cryogenic equipment, and the second and third inner pipes 42 and 43 are used to flow cryogenic fluid at a higher temperature than that, for example, cryogenic fluid. It is said to be used to flow cryogenic fluid for cooling around equipment or exhaust gas returned from cryogenic equipment. And these inner pipes 41, 42, 4
3 and between the outer tube 44 and the vacuum insulation section 4.
It is said to be 5.

To further explain the structure near the connecting portion of the transport pipes 40A, 40B, whose main body portions are configured as described above, each transport pipe 40A, 40B is formed with a flange portion 46A, 46B, respectively. The portion of the transport pipe 40A (hereinafter referred to as the male transport pipe) on the distal end side of the flange portion 46A is a convex male portion 47, and the other transport pipe 40B
(hereinafter referred to as the female side transport pipe) is formed with a concave female part 48 that is retracted from the flange part 46B. The outer wall of the male portion 47 has a portion from its base (the portion on the flange portion 46A side) to the middle portion at a distance l ₁ toward the tip as the outer tube portion 49.
The distance l ₂ from the middle part to the tip consists of three divided outer tube parts 50, 51, and 52. The collective outer tube portion 49 is smaller in diameter than the outer tube 44 of the transportation tube main body portion.
4 and is formed so as to enclose the three inner tubes 41, 42, 43 all at once, similar to the outer tube 44 thereof. Further, the divided outer tube portions 50, 51, 52
is continuous to the outer pipe part 49 and each inner pipe 41, 4
Each inner pipe 41, 4 individually surrounds 2, 43.
It is divided into three parts corresponding to numbers 2 and 43. And the collective outer pipe part 49 and each inner pipe 41, 4
2, 43, and each divided outer tube section 50, 5
1, 52 and their corresponding inner pipes 41, 42,
43 are vacuum insulation parts 53 and 54 that are continuous with the vacuum insulation part 45 of the main body portion of the transport pipe 40A, and each inner pipe 41 and The ends of 42 and 43 are open.

On the other hand, the inner wall of the concave female part 48 is formed of a collective inner wall tube part 55 from the open end position, that is, the flange part 46B position to the intermediate part at a distance l ₁ toward the inner innermost end, A portion of distance l ₂ from the middle portion to the innermost end is composed of three divided inner wall tube portions 56, 57, and 58. The collective inner wall tube part 55 is formed corresponding to the collective outer tube part 49 of the male part 47, and the collective outer tube part 49
The divided inner wall tube portions 56, 57, 58 are configured to be fitted inside the divided outer tube portion 5 of the male portion 47.
0, 51, and 52 are formed so that they are individually fitted inside. And each divided inner wall tube part 56, 57, 5
8, the ends of the corresponding inner tubes 41, 42, 43 of the female transport tube 40B are opened, respectively. The inner walls of each divided inner wall tube section 56, 57, 58 and the outer tube 44 and the inner wall of the collective inner wall tube section 55 and the outer tube 44 are connected to the vacuum insulation section 45 of the main body. Vacuum insulation section 59, 6
It is considered to be 0.

Furthermore, the inner pipes 31 and 4 in the male transport pipe 40A
2 and 43, one of the inner tubes 42 and 43 excluding the first inner tube 41 through which the cryogenic fluid that is required to maintain the lowest temperature flows, that is, the first inner tube The inner tube 42 through which a cryogenic fluid having a relatively higher temperature than the cryogenic fluid flowing through the inner tube 41 is connected to the outer tube portion near the middle portion of the male portion 47 by a heat transfer piece 61A made of a high thermal conductivity material. ing. That is, this heat transfer piece 61A is made of, for example, a copper plate,
Alternatively, it is made of a copper braided tape, a copper alloy plate, etc. In the illustrated example, a tape 62A made of braided copper wire is wrapped around the outer surface of the inner tube 42 at required locations, and a heat transfer piece 61A is placed on the tape 62A. One end is brazed or soldered, and on the other hand, a copper plate or a copper braided tape is applied to the entire boundary surface 63 between the outer tube portion in the middle of the male portion 47, that is, the integral outer tube portion 49 and the divided outer tube portions 50, 51, and 52. 61A is brazed or soldered, and the other end of the heat transfer piece 61A is brazed or soldered to a required location on the plate 64A.

On the other hand, the inner tube 42 of the female side transport tube 40B is similarly connected to the intermediate portion of the inner wall of the female portion 48 via a heat transfer piece 61B made of a high thermal conductivity material. In other words, the copper wire braided tape 62 is attached to the outer surface of the inner tube 42 at required locations.
B is wound, while a copper plate or copper braided tape 64B is brazed or soldered to the entire boundary surface 65 between the collective inner wall tube portion 55 and the divided inner wall tube portions 56, 57, 58, and one end of the heat transfer piece 61B is is brazed or soldered to the braided tape 62B, and the other end is brazed or soldered to the plate 64B.

For cryogenic fluid connections as mentioned above,
Each divided outer tube portion 50, 51, 52 of the convex male portion 47 of the female transport pipe 40A is connected to the female transport pipe 40B.
The corresponding split inner wall tube portion 56 of the concave female portion 48,
57 and 58, the outer tube part 49 of the male part 47 is fitted into the inner wall tube part 55 of the female part 48, and the flange parts 46A and 46B are connected and fixed by bolts or the like.

Here, heat from the outside is transferred to the flange portion 46A,
From position 46B, it attempts to penetrate into the interior by transmitting information through the outer wall (outer tube section) of the female part 47 and the inner wall of the female part. However, the boundary surface 63 at the intermediate portion of the outer tube portion of the male portion 47 and the boundary surface 65 at the intermediate portion of the inner wall of the female portion 48
are directly connected to the inner tube 42 by heat transfer pieces 61A, 61B each made of a high thermal conductivity material such as a copper plate. These heat transfer pieces 61A, 61B have a much higher thermal conductivity than the stainless steel normally used for the outer tube part of the male part 47 and the inner wall of the female part 48, and this tendency is particularly high at extremely low temperatures. Therefore, the temperature gradient between both ends of the heat transfer pieces 61A, 61B is much smaller than the temperature gradient of the outer tube part of the male part 47 and the inner wall of the female part 48,
7, the boundary surface 63 of the middle part of the outer tube part and the female part 48
The temperature of the boundary surface 65 at the middle part of the inner wall is much closer to the temperature of the inner tube 42 than the outside temperature, that is, the temperature is closer to the temperature of the cryogenic fluid flowing inside the inner tube 42. For example, when the external temperature is 300K and the temperature of the cryogenic fluid flowing in the inner tube 42 is 6K, the temperature of each intermediate boundary surface 63, 65 is much closer to 6K than 300K (for example, 30K). Therefore, among the cryogenic fluids flowing through the three inner tubes 41, 42, and 43, the cryogenic fluid that is the lowest and needs to be maintained at that low temperature, for example, the fluid at 4.5 K, flows in the first inner tube 41. When viewed from the corresponding divided outer tube portion 50 of the male portion 47 and the divided inner wall tube portion 56 of the female portion 48, the temperature of the proximal side surfaces, that is, the boundary surfaces 63 and 65, is lower than that of the corresponding divided outer tube portion 50 of the male portion 47 and the temperature of the boundary surfaces 63 and 65 when heat transfer pieces 61A and 61B are not provided. As a result, heat intrusion into the tip of the divided outer tube section 50 and the inner inner end of the divided inner wall tube section 56 (i.e., around the opening of the inner tube 41) is caused by the heat transfer pieces 61A, 61B. The temperature rise of the cryogenic fluid flowing through the inner tube 41 is significantly smaller than that in the case where no inner tube 41 is provided. In other words, almost all heat from the outside is apparently prevented from entering into the divided outer tube section 50 and the divided inner wall tube section 56 corresponding to the inner tube 41 through which the lowest temperature fluid flows.

It is expected that due to heat conduction by the heat transfer pieces 61A and 61B, the temperature of the cryogenic fluid flowing in the inner tube 42 connecting these heat transfer pieces will rise to some extent; A slight rise in temperature does not pose any particular problem because the cold storage fluid or return exhaust gas is flowing around the cryogenic equipment.

Further, in the main bodies of the transport pipes 40A and 40B, it is desirable to provide heat shielding members 66 and 67 inside the exterior 44, as shown in FIG. That is, a hollow cylindrical first heat shielding member 66 is arranged around the inner pipe 41 through which the lowest temperature cryogenic fluid flows so as to surround the inner pipe 41 at intervals. One heat shielding member 66 has three inner tubes 4
The inner tube 41, 43 and the first heat shielding member 66 are fixed in contact with the inner tube 43 through which the cryogenic fluid having an intermediate temperature flows between them. A hollow cylindrical second heat shielding member 67 is arranged so as to surround the second heat shielding member 67, and the second heat shielding member 67 is fixed in a state in contact with the inner pipe 42 through which the relatively highest temperature cryogenic fluid flows. I'll keep it. By doing this, the first inner tube 41, which requires the lowest temperature, is surrounded by the first heat shielding member 66 having approximately the same temperature as the inner tube 43; 43 is surrounded by the second heat shielding member 67 whose temperature is approximately the same as that of the inner tube 42.
The cryogenic fluid flowing through the outer tubes 44 and 43
This effectively prevents the temperature from rising due to radiant heat.

In the embodiment shown in FIGS. 3 to 5, heat transfer pieces 61A and 61 are provided in both the male part 47 and the female part 48.
B is provided, but the outer tube part of the male part 47 and the female part 4
Since heat transfer occurs through mutual contact with the inner walls of the male portion 47, in some cases the heat transfer piece 61 may be attached only to the male portion 47.
A may be provided and the heat transfer piece 61B on the female portion 48 side may be omitted. However, it goes without saying that the effect of the present invention is more fully exhibited when the heat transfer pieces 61A, 61B are provided on both the male part 47 and the female part 48.

Furthermore, in FIG. 3, the tips of the divided outer tube portions 50, 51, 52 of the male portion 47 correspond to the respective divided inner wall tube portions 56, 57, 58 of the female portion 48.
is shown in direct contact with the innermost edge of the
Actually, it goes without saying that an elastic ring made of Teflon or the like may be interposed between them.

Further, in the above example, three inner tubes are housed in the same outer tube, but it goes without saying that two or four or more inner tubes may be housed in the same outer tube.

Effects of the Invention As is clear from the above explanation, the connection structure of the cryogenic fluid transport pipe of the present invention is such that a plurality of inner pipes through which cryogenic fluids of different temperatures flow are accommodated in the same outer pipe. It connects the main bodies of the transport pipes with vacuum insulation between the pipes and the outer pipe, and the outer pipe part of the convex male part on the connection side of the male transport pipe is The inner wall of the concave female part on the connecting side of the female transport pipe The outer tube portion of the male portion has a configuration corresponding to the male portion, and the middle portion of the outer tube portion of the male portion is made of a heat transfer piece made of a high thermal conductivity material such as copper, so that it is the most flexible of the plurality of inner tubes. An inner tube excluding the inner tube through which a low-temperature fluid (or a fluid that should be maintained at a low temperature) flows, that is, a male outer tube portion that is directly connected to the inner tube through which a relatively high-temperature fluid flows. The temperature of the middle part of the tube is a low temperature close to the temperature of the fluid flowing in the inner tube connected by the heat transfer piece, and as a result, the split outer tube surrounding the connecting end of the inner tube through which the coldest fluid flows Almost all heat intrusion from the outside is apparently prevented from entering the inner tube, and the temperature rise due to heat intrusion from the divided outer tube section of the lowest temperature fluid flowing in the inner tube becomes extremely small. As described above, according to the connection structure of the present invention, when a plurality of cryogenic fluids at different temperatures are transported through the same transport pipe, the fluid with the lowest temperature (or the lowest temperature is maintained) among the fluids It is possible to prevent the temperature rise due to heat intrusion at the connection part as much as possible, especially when the fluid is a gas and the flow rate is small. A remarkable effect can be obtained to avoid the increase in the amount of water. In addition, in this invention, three or more inner tubes are accommodated in the same outer tube to
It is also possible to transport more than one type of fluid at the same time, and therefore the piping work can be much easier compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a conventional general cryogenic fluid transport pipe connection structure; FIG. 2 is a cross-sectional view showing another example of a conventional cryogenic fluid transport pipe connection structure; Figure 3 shows the connection structure of a cryogenic fluid transport pipe according to an embodiment of the present invention, and is a cross-sectional view with the male and female sides removed (however, to simplify the drawing, three lines are shown). Figure 4 shows the inner tubes 41, 42, 43 arranged on the same plane), and Figure 4 is similar to Figure 3.
5 is a sectional view taken along the - line in FIG. 3 (however, FIGS. 4 and 5 show the three inner tubes 41, 42, 43 in their true arrangement positions);
FIG. 6 is a cutaway perspective view showing a desirable example of a main body portion of a transport pipe to which the present invention is applied. 40A, 40B...transport pipe, 41, 42, 43...
Inner tube, 44...Outer tube, 45...Vacuum insulation part, 47...Male part, 48...Female part, 49...Bulk outer pipe part, 50,5
1, 52...Divided outer pipe part, 53, 54...Vacuum insulation part, 55...Bulk inner wall pipe part, 56,57,58...Divided inner wall pipe part, 59,60...Vacuum insulation part, 61A,
61B...Heat transfer piece.

Claims (1)

[Claims] 1. A plurality of inner tubes 41, 42, 43 through which cryogenic fluids of different temperatures flow are housed in the same outer tube 44 in parallel at intervals, and A vacuum insulation section 4 is provided between each other and between each inner tube and outer tube.
A connecting part structure for mutually connecting cryogenic transport tubes 40A and 40B, which are referred to as No. 5; A convex male part 47 is formed to fit into the formed concave female part 48, and a predetermined length of the outer wall of the convex male part extends from the base of the male part to the tip. The part from the intermediate part to the tip is composed of a collective outer pipe part 49 that is continuous with the outer pipe of the transport pipe main body part and surrounds the plurality of inner pipes all at once. The portion is composed of divided outer tube portions 50, 51, and 52 that are continuous with the collective outer tube portion and are divided corresponding to each inner tube so as to individually surround the plurality of inner tubes. Furthermore, the ends of the inner tubes are opened at the distal end surfaces of each of the divided outer tube sections, and the ends of the inner tubes are opened between the collective outer tube section and the inner tube inside thereof, and between each of the divided outer tube sections and the inner tube inside thereof. Vacuum insulation parts 53 and 54 are connected to the vacuum insulation part of the main body of the transport pipe, respectively, and vacuum insulation parts 53 and 54 are connected to the vacuum insulation part of the main body of the transport pipe. The part between the middle part of the distance is composed of a collective inner wall pipe part 55 into which the collective outer pipe part of the male part is fitted, and the part from the middle part to the inner end is composed of the collective inner wall pipe part 55. divided inner wall tube portions 56, 57, and 58 that are continuous with and into which the divided outer tube portions of the male portion are individually fitted;
In addition, the corresponding end of the inner tube is opened at the inner end of each divided inner wall tube, and between the female part of the inner wall tube and the outer tube and the divided inner wall tube. Vacuum insulation parts 59 and 60 are connected to the vacuum insulation part of the transport pipe main body part between the part and the outer pipe.
Further, in at least the male part of the male part and the female part, an inner pipe through which relatively high temperature cryogenic fluid flows among the plurality of inner pipes and an outer pipe near the middle part of the male part. A connecting part structure for a cryogenic fluid transport pipe, characterized in that the connecting part is connected to the part by a heat transfer piece 61A made of a material with high thermal conductivity.