JPH0315074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cryogenic fluid transfer tube, and particularly to a cryogenic fluid transfer tube suitable for transferring a cryogenic fluid such as liquid helium.

[Background of the invention]

A cryogenic fluid transfer pipe for transferring a cryogenic fluid such as liquid helium includes, for example, an inner pipe through which the cryogenic fluid flows, and an outer pipe of the inner pipe, as described in Japanese Patent Application Laid-Open No. 56-131885. A heat shield tube is installed to form a vacuum insulation space with the outer surface of the inner tube, a cooling tube is fixed to the outer surface of the heat shield tube by silver brazing, etc., and a heat shield tube is attached to the outside of the heat shield tube. It is known that the tube is composed of an outer surface and an outer tube disposed to form a vacuum insulation space.

In such a low-temperature fluid transfer pipe, heat that enters the low-temperature fluid flowing through the inner pipe from the outside (hereinafter referred to as "invasive heat") is absorbed and removed (hereinafter referred to as heat absorption) along the way. The heat shield tube is cooled by flowing a cooling medium through the cooling tube.

However, in such low-temperature fluid transfer tubes, the cooling tube is fixed to the heat shield tube by silver brazing, etc., so the cooling efficiency of the heat shield tube by the cooling medium flowing through the cooling tube is insufficient. Therefore, the heat shield tube has an insufficient effect of absorbing the intruding heat, which is one of the reasons for inhibiting the improvement of the transfer efficiency of the low-temperature fluid.

[Purpose of the invention]

The purpose of the present invention is to efficiently transmit the cooling heat from the cooling tube to the heat shield tube, efficiently absorb the radiant heat from the outer tube, increase the shielding effect, and improve the transfer efficiency of the low-temperature fluid flowing inside the inner tube. The purpose of the present invention is to provide a low-temperature fluid transfer pipe that can be used.

[Summary of the invention]

The present invention provides an inner tube for transferring a low-temperature fluid, an outer tube that is provided surrounding the inner tube and forms a vacuum insulation space in the inner space between the inner tube and the outer tube, and a space between the inner tube and the outer tube. Consisting of a double-shielded tube in which a heat-conducting medium is placed inside the double-shielded tube, which is isolated from the vacuum heat-insulated space, and a cooling tube that passes through the double-shielded tube and cools the shielded tube via the heat-conductive medium, The cooling heat from the cooling tube is efficiently transmitted to the shield tube, and the radiant heat from the outer tube is efficiently absorbed, increasing the shielding effect and improving the transfer efficiency of the low-temperature fluid flowing inside the inner tube. .

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, the cryogenic fluid transfer pipe 10 is an inner pipe 1 through which a cryogenic fluid such as liquid helium flows.
1, a heat shield tube 12 disposed outside the inner tube 11, and another heat shield tube disposed outside the heat shield tube 12 to form a heat conduction medium atmosphere 13 with the outer surface of the heat shield tube 12. 14, a cooling pipe 15 disposed in the heat conduction medium atmosphere 13, and an outer tube 16 disposed outside the other heat shield tube 14. In this case, the heat shield tube 12 and the other heat shield tube 14 form a double shield tube. Further, between the outer surface of the inner tube 11 and the inner surface of the heat shield tube 12, for example, a vacuum insulation space 1 is provided.
7 is formed, and between the outer surface of the other heat shield tube 14 and the inner surface of the outer tube 16, for example, a vacuum insulation space 18 is formed.

In FIGS. 1 and 2, a low-temperature fluid, such as liquid helium, is made to flow through the inner tube 11, and a cooling medium, such as liquid nitrogen, is supplied to the cooling pipe 15 and made to flow therein. . The heat conduction medium atmosphere 13 is, for example, a helium gas atmosphere. In this state, the heat shield tube 12 and other heat shield tubes 14 are sufficiently cooled to around 77K, which is the temperature of liquid nitrogen, by heat conduction of the helium gas. As a result, the absorption effect of the intrusion heat that intrudes from the outer tube 16 into the other heat shield tube 14 is reduced.
4 is fully demonstrated. Therefore, the amount of heat that enters the liquid helium flowing inside the inner tube 11 from the outside is suppressed to a small value, and the evaporation of the liquid helium flowing inside the inner tube 11, that is, the heat loss is suppressed to a small value.

In this embodiment, the following effects can be obtained.

(1) Since the heat shield tube and other heat shield tubes can be sufficiently cooled by the liquid nitrogen flowing through the cooling tube, the heat shield tube and other heat shield tubes can fully utilize the heat absorption effect of the intruding heat inside the inner tube. It is possible to improve the transfer efficiency of liquid helium that flows through it.

(2) Since there is no need to fix the cooling pipe to the heat shield pipe or other heat shield pipes, the man-hours for manufacturing the low temperature fluid transfer pipe can be reduced.

A second embodiment of the present invention will be explained with reference to FIG.

The differences in FIG. 3 from FIGS. 1 and 2, which show one embodiment of the present invention described above, are an inner tube 11', a heat shield tube 12', another heat shield tube 14', and a cooling tube 1.
5' and outer tube 16' are all or partially formed of flexible tubes, such as bellows tubes. In FIG. 3, other parts that are the same as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted.

In this embodiment, in addition to the effects of the embodiment of the present invention described above, the following effects can be obtained.

(1) The cryogenic fluid transfer pipe can be made flexible.

(2) Since the outer surface area of the cooling tube increases and the contact area with the heat transfer medium increases, the cooling efficiency of heat shield tubes and other heat shield tubes can be further improved, and as a result, the liquid flowing inside the inner tube increases. The transfer efficiency of low-temperature fluids such as helium can be further improved.

A third embodiment of the present invention will be explained with reference to FIG.

The difference between FIG. 4 and FIGS. 1 and 2, which show an embodiment of the present invention described above, is that the heat conduction medium atmosphere
3, the cooling pipe 15'' is arranged in a spiral shape on the outside of the heat shield tube 12.In addition, in FIG. 4, other components that are the same as those in FIG. 1 and FIG. omitted.

In this embodiment, in addition to the effects of the embodiment of the present invention described above, the following effects can be obtained.

(1) The outer surface area of the cooling tube increases, and the contact area with the heat transfer medium increases, so the cooling efficiency of heat shield tubes and other heat shield tubes can be further improved, and as a result, the liquid flowing inside the inner tube increases. Transfer efficiency of low-temperature fluids such as helium can be improved.

A fourth embodiment of the present invention will be explained with reference to FIG.

In FIG. 5, one end of the heat conduction medium supply line 19 is connected to one end side (the right end side in FIG. 5) of the other heat shield tube 14 in communication with the heat conduction medium atmosphere 13, and the heat conduction medium The other end of the supply line 19 is connected to a low temperature liquefied gas container 20 installed outside the low temperature fluid transfer pipe 10 in communication with a gas phase section 21 .
For example, a shutoff valve 22 is provided in the heat conduction medium supply line 19. Other heat shield tube 1
4 (the left end side in FIG. 5), one end of the heat conduction medium discharge line 23 is connected to the heat conduction medium atmosphere 13.
The thermal conductive medium discharge line 23 is connected in communication with the
The other end is outside the outer tube 16 and is open to the atmosphere, for example. For example, a shutoff valve 24 is provided in the heat conduction medium discharge line 23. Also,
An extraction pipe 26 is provided at one end of the inner pipe 11 with one end immersed in the liquid phase part 25 of the low-temperature liquefied gas container 20.
The other end is connected. In FIG. 5, other components that are the same as those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted.

In FIG. 5, for example, liquid helium is stored in the low temperature liquefied gas container 20, and the helium gas evaporated from the liquid helium is transferred to the gas phase part 21.
It is stored in For example, when the helium gas in the heat conduction medium atmosphere 13 becomes diluted, the helium gas stored in the gas phase section 21 is supplied to the heat conduction medium atmosphere 13 via the heat conduction medium supply line 19, and this As a result, the heat transfer medium atmosphere 13 is filled with helium gas. After such helium gas filling, the shutoff valves 22 and 24 are closed, and the heat transfer medium atmosphere 13 is shut off.

In this embodiment, in addition to the effects of the embodiment of the present invention described above, the following effects can be obtained.

(1) Since helium gas can be replenished into the heat transfer medium atmosphere, it is possible to prevent fluctuations in the cooling efficiency of heat shield tubes and other heat shield tubes due to dilution of helium gas in the heat transfer medium atmosphere. The shield tube can always be cooled stably.

(2) Since the helium gas evaporated from the liquid helium stored in the low-temperature liquefied gas container is used as the replenishment gas, there is no need to install a special helium gas source for replenishment, and the transfer of liquid helium is The cost required for this can be reduced.

A fifth embodiment of the present invention will be explained with reference to FIG.

In FIG. 6, one end of the heat conduction medium supply line 19' is connected to one end side (the left end side in FIG. 6) of the other heat shield tube 14 so as to communicate with the heat conduction medium atmosphere 13. The other end of the conductive medium supply line 19' is connected to a low-pressure return gas line 33 that connects the inlet of a helium compressor 31 constituting a cryogenic liquefaction refrigeration system, for example, a helium liquefaction refrigeration system 30, and a cold box 32. ing. For example, a shutoff valve 2 is provided in the heat conduction medium supply line 19'.
2' is provided. At the other end side (the right end side in FIG. 6) of the other heat shield tube 14, one end of the heat conduction medium discharge line 23' is connected to the heat conduction medium atmosphere 13.
The other end is outside the outer tube 16 and is open to the atmosphere, for example. For example, a shutoff valve 24' is provided in the heat transfer medium discharge line 23'. Further, at one end of the inner pipe 11, a liquid helium supply pipe 2 that has exited the cold box 32 is provided.
7 is connected, and the other end of the inner tube 11 is connected to, for example, another liquid helium supply tube 27' whose one end is open inside the low-temperature liquefied gas container 20.
Further, the liquid helium supply pipe 27 and the other liquid helium supply pipe 27' are vacuum insulated. In FIG. 6, other components that are the same as those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted.

In this embodiment, in addition to the effects of the fourth embodiment of the present invention described above, the following effects can be obtained.

(1) Helium gas can be replenished into the heat transfer medium atmosphere in a short time.

(2) Since the pressure of the heat transfer medium atmosphere becomes higher, thermal conductivity increases and cooling efficiency improves.

A sixth embodiment of the present invention will be described with reference to FIG.

The difference from FIG. 6 which shows the fifth embodiment of the present invention described above in FIG. Another return gas pipe 28' enters the return gas pipe 28 and the other end enters the cold box 32.
At the same time, the other end of the heat conductive medium supply line 19'', one end of which is connected to the return gas pipe 28, is connected to one end of the other heat shield pipe 14 in the heat conductive medium atmosphere 1.
It is a point that communicates and connects with 3. In addition, in FIG. 7, other components that are the same as those in FIG. 6 are indicated by the same reference numerals, and explanations thereof will be omitted.

In this embodiment, in addition to the effects of the embodiment of the present invention described above, the following effects can be obtained.

(1) Since there is no need to use liquid nitrogen separately as a cooling medium, the cost required for transporting liquid helium can be reduced accordingly.

(2) The flow of helium gas into the cooling pipe and the filling of helium gas into the heat transfer medium atmosphere can be performed in conjunction with each other, which further simplifies the operation.

〔Effect of the invention〕

According to the present invention, since the cooling heat from the cooling tube can be efficiently transmitted to the heat shield tube, the radiant heat from the outer tube can be efficiently absorbed and the shielding effect can be increased, and the low temperature flowing inside the inner tube can be efficiently absorbed. This has the effect of improving fluid transfer efficiency.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the cryogenic fluid transfer pipe according to the present invention, and FIG.
3 is a vertical sectional view showing a second embodiment of the cryogenic fluid transfer pipe according to the present invention, and FIG. 4 is a vertical sectional view showing a third embodiment of the cryogenic fluid transfer pipe according to the present invention. 5 is a vertical sectional view showing a fourth embodiment of the cryogenic fluid transfer pipe according to the present invention, and FIG. 6 is a longitudinal sectional view showing a fifth embodiment of the cryogenic fluid transfer pipe according to the present invention. FIG. 7 is a longitudinal sectional view showing a sixth embodiment of the cryogenic fluid transfer tube according to the present invention. 11... Inner tube, 12, 12'... Heat shield tube,
13... Heat conduction medium atmosphere, 14, 14'... Other heat shield tubes, 15, 15', 15''... Cooling tube, 16, 16'... Outer tube.

Claims (1)

[Scope of Claims] 1. An inner pipe for transferring a low-temperature fluid, an outer pipe surrounding the inner pipe and forming a vacuum insulation space in the inner space between the inner pipe and the outer pipe. a double-shielded tube provided between the tube and a heat-conducting medium placed inside the vacuum-insulated space, and cooling the shielded tube through the heat-conductive medium that passes through the double-shielded tube. 1. A cryogenic fluid transfer pipe comprising a cooling pipe. 2. The cryogenic fluid transfer pipe according to claim 1, wherein a part of the refrigerant from the equipment or the cooling pipe to which the end of the inner pipe is connected is supplied as the heat transfer medium.