JPH071593Y2 - Cryogenic fluid transfer pipe joint structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cryogenic fluid transfer pipe for transferring a cryogenic fluid such as liquid hydrogen or liquid helium, and in particular, the pipes or pipes are used as container nozzles. The present invention relates to a joint structure of a pipe for cryogenic fluid transfer, which has an improved joint part with.

[Prior Art] Generally, when transferring a cryogenic fluid such as liquid hydrogen or liquid helium, heat input from the outside evaporates the cryogenic fluid in the transfer pipe, and reduces the vibration and heat loss of the pipe caused by this. In order to do so, piping having a structure as shown in FIG. 2 is used.

As shown in the figure, the transfer pipe a has a double pipe structure composed of an inner pipe b for substantially transferring the cryogenic fluid and an outer pipe c separated by a predetermined space so as to cover the inner pipe b. Has become. Then, a vacuum heat insulating layer d is formed so that the space between the inner tube b and the outer tube c is in a vacuum state.

Therefore, the external heat input from the outside of the transfer pipe a into the inner pipe b is insulated by the vacuum heat insulating layer d, and the thermal influence on the cryogenic fluid flowing through the inner pipe b is reduced.

Further, as a joint structure for connecting the transfer pipes a having such heat insulating properties, a bayonet joint structure e as shown in the figure is used in order to reduce external heat input at the joint portion.

This bayonet joint structure e has an inner tube b1 of one transfer tube a1.
A male bayonet cylinder f having a double tube structure by folding back the end of the first pipe and a first flange g extending outwardly in the radial direction of the transfer pipe a1 so as to cross the outer pipe c1 from the folded end. When,
A female bayonet tube h formed by expanding the inner tube b2 of the other transfer tube a2 into a diameter slightly larger than the inner tube b2 so that the male bayonet tube f can be inserted, and an outer tube c2 from this end. It is mainly composed of a second flange i extending outward in the radial direction of the transfer pipe a2 so as to traverse.

Therefore, in order to connect the transfer pipes a1 and a2 to each other, the first flange g and the second flange i are clamped by the O-ring K and the bolt j is inserted.
And the like, the male bayonet tube f is inserted into the female bayonet tube h, and the respective transfer tubes a are inserted.
The inner pipes b1 and b2 of 1 and a2 communicate with each other. On this occasion,
The cryogenic fluid in the inner pipes b1 and b2 penetrates through the seal m into the gap 1 between the male bayonet cylinder f and the female bayonet cylinder h that is slightly larger than this, and is vaporized and Will stay in.

Therefore, the presence of the bayonet cylinders f and h lengthens the path of heat entering from the outside air and reduces the thermal effect on the cryogenic fluid.

[Problems to be solved by the invention] However, for example, when the outside air temperature is 20 ° C, the temperature difference between the heat input from the joint and liquid helium (-269 ° C at atmospheric pressure) which is a cryogenic fluid is about Since there was a very large temperature difference of 290 ° C, the adiabatic joint could not be said to have a sufficient heat insulating effect. That is, when the cryogenic fluid is transferred in the transfer pipe, external heat is input through this joint, and the cryogenic fluid is evaporated in the transfer pipe.
Gas) causes problems such as vibration of the transfer pipe and evaporation loss.

The object of the present invention, which was devised in consideration of the above circumstances, is to cool the joint portion with liquid nitrogen or the like to reduce the temperature difference with the cryogenic fluid to reduce heat loss and to reduce the wear of the joint portion. (EN) A joint structure for a cryogenic fluid transfer pipe that prevents frost.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an inner tube for transferring a cryogenic fluid such as liquid hydrogen or liquid helium with an outer tube, and a vacuum state between them, In the joint structure of the cryogenic fluid transfer pipe in which the outer pipe is connected with a flange and a bayonet joint for connecting the inner pipes to the flange is provided, a middle pipe for introducing liquid nitrogen into the vacuum space inside the outer pipe is provided. , The intermediate pipe and the flange are connected by a thermal anchor for heat conduction, and a sleeve for performing heat cutting in the radial direction of the flange is provided on the flange on the outer periphery of the thermal anchor. Since the invention is configured as described above, when a cryogenic fluid such as liquid helium is transferred from one transfer pipe through the joint to the other transfer pipe or container, the joint flows into the middle pipe. And it has been cooled through a thermal anchor by liquid nitrogen are, are very small heat input to the cryogenic fluid. Further, there is a possibility that frost may form on the joint portion by cooling the joint portion with liquid nitrogen, but since heat is insulated by the sleeve provided on the joint portion flange, frost formation on the joint portion is prevented.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a joint structure 1 of transfer pipes for transferring a cryogenic fluid connects a transfer pipe 2 and a transfer pipe 3 with a bayonet joint 8.

For convenience of explanation, FIG. 1 will be described with an example in which the invention is implemented only on the transfer pipe 2 side.

As shown in the figure, the transfer pipes 2 and 3 are formed with inner pipes 4 and 4a for transferring a cryogenic fluid at their axial center portions, and the inner pipes 4 and 4a are surrounded by a predetermined space so as to surround them. Separate the outer tube 5,5a
The inner tubes 4, 4a and the outer tubes 5, 5a are formed with vacuum heat insulation layers 6, 6a which are made vacuum for heat insulation. The transfer pipes 2 and 3 are connected to the bayonet joint 8
Connected by. The bayonet 8 is a transfer tube that crosses the male bayonet sleeve 4b in which the end of the inner tube 4 of one transfer tube 2 is folded back to form a double tube structure and the outer tube 5 from this folded end. The first flange 9 extending outward in the radial direction of 2 and the inner tube 4a of the other transfer tube 3 are expanded to a diameter slightly larger than this so that the male bayonet sleeve 4b can be inserted. It is mainly composed of a molded female bayonet sleeve 4c and a second flange 10 extending from the end of the female bayonet sleeve 4c outward in the radial direction of the transfer tube 3 so as to cross the outer tube 5a.

In addition, the vacuum heat insulating layer 6 in the space between the inner tube 4 and the outer tube 5 of the transfer tube 2
Inside, a middle pipe 7 is provided outside the inner pipe 4 at a predetermined interval so as to surround the inner pipe 4.

The middle pipe 7 has a double pipe structure in which a small-diameter pipe 7a is inserted into a large-diameter pipe 7b, and the ends of the pipe 7a and the pipe 7b are hermetically sealed so that liquid nitrogen or the like can flow into the inside. A thermal anchor 11 is provided at the end of the middle pipe 7 for connecting the middle pipe 7 and the first flange 9 to each other.

Further, the first flange 9 of the transfer pipe 2 is provided with a heat cutting sleeve 12 for cutting the first flange 9 in the radial direction. The heat cutting sleeve 12 is formed on the outer circumference of the thermal anchor 11 and is formed by hollowing the pipe 12a in the vacuum heat insulating layer 6 so as to reduce the heat input from the first flange 9.

Then, in order to connect the transfer pipes 2 and 3, the first flange 9 and the second flange 10 are inserted into the O-ring 13 and the bolt 14 is inserted.
Female bayonet sleeve 4c when joined with fasteners such as
Then, the male bayonet sleeve 4b is inserted into the inner pipes 4 and 4a of the transfer pipes 2 and 3, respectively.
At this time, the tip of the male bayonet sleeve 4b is sealed.
The inner pipes 4 and 4a are closed by 15.

Next, the operation of the present invention will be described.

A cryogenic fluid such as liquid helium is transferred from the transfer pipe 2 through the joint portion 8 to the transfer pipe 3 as indicated by an arrow in the figure. At this time, heat input from the first flange 9 and the second flange 10 of the joint portion 8 is generated by the female bayonet sleeve.
4c and the male bayonet sleeve 4b reduce the BOG generation due to heat input, but the first flange 9 is further heated by the liquid nitrogen flowing into the middle pipe 7 to provide thermal anchoring. It is cooled via 11, and the heat input to the cryogenic fluid is extremely small. Further, there is a possibility that frost may be formed on the first flange 9 by cooling the first flange 9 with liquid nitrogen, but heat is provided by the sleeve 12 provided on the first flange 9 to prevent frost formation on the first flange 9. To prevent.

That is, when the outside air temperature is 20 ° C, the temperature difference with liquid helium (-269 ° C at atmospheric pressure), which is a cryogenic fluid, is about 290 ° C.
There was an extremely large temperature difference, and the adiabatic joint had a poor heat insulating effect. Therefore, the first flange 9 is cooled by the liquid nitrogen (−196 ° C. under atmospheric pressure) that has flowed into the middle pipe 7, and the temperature difference between the liquid helium and the first flange 9 is reduced to generate BOG of liquid helium. It has become possible to keep the value low.

[Effect of the Invention] The present invention has the following excellent effects.

(1) By reducing the generation of BOG, energy efficiency is improved, and vibration of the pipe due to BOG is prevented, and reliability is improved.

(2) By providing the heat cutting sleeve, it is possible to prevent frost formation on the flange portion.

[Brief description of drawings]

FIG. 1 is a sectional view of a joint structure of a cryogenic fluid transfer pipe according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional bayonet joint structure. In the figure, 1 is the joint structure of the cryogenic fluid transfer pipe, 4, 4a inner pipe,
5, 5a is an outer pipe, 7 is a middle pipe, 8 is a bayonet joint, 9 and 10 are flanges, 11 is a thermal anchor, and 12 is a sleeve.

Claims (1)

[Scope of utility model registration request] 1. An inner pipe for transferring a cryogenic fluid such as liquid hydrogen or liquid helium is covered with an outer pipe, a vacuum state is provided between them, and the outer pipe is connected with a flange, and the inner pipe is attached to the flange. In a joint structure of a cryogenic fluid transfer pipe provided with a bayonet joint to be connected, a middle pipe for introducing liquid nitrogen into a vacuum space in an outer pipe is provided, and the middle pipe and the flange are connected by a thermal anchor for heat conduction. Connect
Further, a joint structure for a cryogenic fluid transfer pipe, characterized in that a sleeve for performing heat cutting in a radial direction of the flange is provided on a flange on the outer periphery of the thermal anchor.