JPH0243953B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an improved refrigerant transport pipe that is capable of effectively evacuation of a layer of laminated insulation material in a pipe that transports cryogenic refrigerant, and a refrigerant transport pipe therefor. The present invention attempts to provide a vacuum evacuation method.

[Conventional technology]

Generally, in tubes that transport cryogenic refrigerants such as liquid helium, vacuum insulation and super insulation (hereinafter referred to as SI) are used in combination on the circumference of the tube to secure the refrigerant passage. It has a heat insulating structure to maintain the cryogenic temperature.

FIG. 1 shows a conventional refrigerant transport pipe realized based on such a basic concept, in which a first inner pipe 4 is installed via a spacer 10 on an inner pipe 2 that secures a refrigerant passage 1. A vacuum insulation layer 3 is formed between them by coaxial arrangement, and a second middle pipe 6 is coaxially arranged over the first middle pipe 4 via a spacer 10 to secure a refrigerant return space 5 between them. Then, an SI layer 7 made of multiple layers of SI material is formed on the second middle pipe 6,
The structure is such that an outer tube 9 is placed coaxially thereon with a spacer 10 interposed therebetween, and a vacuum evacuation space 8 is secured between them.

The SI layer 7 is made of synthetic fibers such as polyethylene terephthalate (for example, "Mylar" from Dapon) with aluminum deposited on both sides, polyamide known under the trademark nylon, or polyester known under the trademark Tetron. Multi-layer (10
It is wrapped in layers (more than one layer).

Since this SI material has gas attached to it that can reduce the radiation insulation effect, it is evacuated through the evacuation layer 8 provided adjacent to the SI layer 7 to promote vaporization and separation of the gas. are doing.

[Problem to be solved by the invention]

The SI layer 7 is evacuated by evacuation using a vacuum pump or the like from the end of the tube, but if the tube is wound in multiple layers as described above, complete evacuation cannot be performed. The reality is that it is difficult.

Incidentally, in order to completely evacuate the inside of the SI layer, the conductance of the SI layer is small in both the radial and longitudinal directions, and in such a multilayer tightly wound structure, it takes an extremely long time to evacuate, which is impractical. Ta.

Therefore, as a way to solve the above problem,
Adsorbent material (for example, "Molecular Thieves" manufactured by Union Carbide Corporation in the United States) is made into a string and wrapped around the SI layer vertically or in long pitches to adsorb and capture gas from the SI layer, and then vacuum pumped. Methods are being adopted to make work more efficient.

However, even with such a gas adsorption method, as the length of the transport tube increases, the exhaust conductance decreases in inverse proportion to the length of the tube, so that satisfactory results have not always been obtained.

Incidentally, with such an adsorbent, when the adsorbent adsorbs gas and reaches a saturated state, no further gas adsorption occurs, and if a high degree of vacuum is obtained by complete gas release, it is incomplete. I have to say it was a great method. In order to solve the gas adsorption saturation problem of such adsorbents, a method has been adopted that involves heating the adsorbent whose gas adsorption is saturated to 80 to 100°C and expelling the adsorbed gas. However, the heating method that could actually be used was to blow hot air from the end of the tube, so it could be avoided that the baking effect deteriorates as the length of the tube increases. Unable to do so.
Particularly in the longitudinal center of the tube, there was a tendency for the adsorbed gas to not be discharged sufficiently due to the fact that hot air could not enter sufficiently and the temperature of the hot air that had been sent into the tube decreased.

In view of the above-mentioned problems, the present invention makes it possible to sufficiently adsorb gas from the SI layer, especially at the central portion in the longitudinal direction of the tube, thereby shortening the evacuation time for the SI layer and improving the degree of vacuum. The purpose of the present invention is to provide a refrigerant transport pipe with a new vacuum evacuation structure and a vacuum evacuation method therefor.

[Means to solve the problem]

In order to achieve the above object, the refrigerant transport pipe of the present invention penetrates in the radial direction through a spacer that is arranged in the longitudinal direction in contact with the SI material in order to secure a vacuum evacuation space adjacent to the SI material. It consists of a perforated tube having a large number of holes, and a spherical adsorbent having an outer diameter smaller than the inner diameter of the tube is housed inside the perforated tube.

In addition, the vacuum evacuation method for such a refrigerant transport pipe is such that the spherical adsorbent is removed from the refrigerant transport pipe constructed as described above by rotating a drum wound around the refrigerant transport pipe. With the tube placed in the center in the longitudinal direction, the tube is evacuated by drawing a vacuum from both ends of the tube, and when the vacuum reaches saturation, the tube is placed in the center of the tube and adsorbs gas. The spherical adsorbent is moved to the end of the transport pipe by the rotation of the drum and baked to discharge the adsorbed gas, and the regenerated spherical adsorbent is transferred to the transport pipe by the rotation of the drum again. The main purpose is to move it to the center and perform vacuum evacuation.

[Effect]

According to the refrigerant transport pipe of the present invention described above, the gas adhering to the SI material constituting the SI layer is contained in the pipe through the numerous holes penetrating in the radial direction of the holed pipe of the spacer in contact with the SI material. It is adsorbed by the adsorbent material. However, since the adsorbent is housed in a spherical shape with an outer diameter smaller than the inner diameter of the perforated tube, it can be moved in the longitudinal direction of the refrigerant transport pipe by rolling it inside the perforated pipe. By making it possible to adsorb gas from the SI material at any position in any direction, and by concentrating gas adsorption in the longitudinal center of the refrigerant transport pipe, where it is difficult to vaporize and separate the gas by vacuuming, Evacuation work can be performed efficiently and in an extremely short time.

In addition, on both sides of the spacer in contact with the SI material,
Since a space is formed adjacent to the material, by evacuating this space, the inside of the spacer's holed tube is also evacuated through the numerous radial through holes in its own tube wall, and radiation is emitted. Factors that reduce the heat insulation effect can be eliminated.

An adsorbent that continues to adsorb gas will reach a so-called saturated state where it no longer adsorbs gas, and will no longer be of any use as it is, but it can be regenerated by expelling the gas through baking.

As mentioned above, the adsorbent can be moved in the longitudinal direction of the refrigerant transport pipe, so by rolling and moving it in the longitudinal direction of the perforated pipe, the adsorbent can be heated to 80 to 100°C. It can be moved to the end side of the refrigerant transport pipe where the conditions for baking are best and the exhaust conductance is greatest.

According to the vacuum evacuation method of the present invention for a refrigerant transport pipe whose evacuation structure has been improved as described above, the refrigerant transport pipe having the above-mentioned structure is evacuated by rotating a drum that winds up the refrigerant transport pipe. The adsorbent rolls within the perforated tube that houses it and is moved to the center of the refrigerant transport tube.

The adsorbent moved to the middle of the refrigerant transport pipe as described above is not particularly fixed inside the perforated pipe, but can be easily moved from that position by drawing a vacuum from both ends of the refrigerant transport pipe. The gas adsorption is performed intensively at the center of the tube without causing any damage.

When the adsorbent reaches a saturated state where it continues to adsorb gas and cannot do so, it is moved to the end of the refrigerant transport pipe with a large exhaust conductance by the rotation of the drum, so the adsorbed gas can be efficiently discharged by baking. can.

The adsorbent that has been baked and regenerated to be able to adsorb gas as described above is moved to the middle of the transport pipe by the rotation of the drum again, and adsorbs the remaining gas that could not be adsorbed completely. A higher degree of vacuum can be obtained by continuing evacuation.

〔Example〕

FIG. 2 shows a preferred structural example of a refrigerant transport pipe provided with an evacuation structure according to the present invention. In this figure, the structure from the inner pipe for securing the refrigerant passage to the refrigerant return path secured in the second intermediate pipe is omitted. Since most of these are the same as those in the first part, please refer to the same figure and the above-mentioned explanation thereof.

As is clear from Figure a showing the overall structure of the refrigerant transport pipe of this embodiment, three spacers 11, 11, 11 are arranged at equal intervals (120°) in the circumferential direction on the outer surface of the second middle pipe 6. They are arranged vertically in the length direction or wound in long pitches with a distance of , and an SI layer 7 made of multilayer winding of SI material is provided on top of the SI layer 7.

The outer tube 9 is disposed coaxially with the second inner tube 6 on the outside of the SI layer 7 which is wound in a non-circular manner due to the interposition of the spacer 11, and the outer tube 9 is arranged coaxially with the second inner tube 6, and the outer tube 9 is arranged coaxially with the second inner tube 6. It is inscribed in the outer surface and the gap formed between adjacent contact parts is used as an evacuated space 8.
In addition, a gap is formed on both sides of the spacer 11 by the lifting of the inner surface of the SI layer 7, and this gap is also secured as an evacuation space 8.
used as.

The spacer 11, as shown in FIG. A granular adsorbent 1 is placed inside a spherical cover 14 with a hole with a small diameter.
3 is housed in an appropriate number, and the cover 14 rolls against the holed tube 11 to enable movement in the longitudinal direction of the tube.

Figure c shows another example of the structure for accommodating the adsorbent in the perforated tube 11, in which the adsorbent 13 itself is formed into a spherical shape, and the manner in which it is accommodated is the same as that in Figure a. .

The spacer 11 having such a structure is arranged such that an arbitrary number of spherical adsorbents 13 are set inside a tube with holes so that the tube with holes is inscribed in the SI layer 7.

As described above, the refrigerant transport pipe incorporating the adsorbent is wound around a drum and made into a long piece, but especially if it is made to be a long piece of several tens of meters or more, the evacuation method according to the present invention can be used. The meaningfulness of is demonstrated.

Prior to vacuum evacuation, both ends of the drum-wound refrigerant transport pipe, including the beginning and end of the roll, are sealed, and a vacuum is drawn from both ends of the transport pipe using a vacuum pump. As,
The drum around which the refrigerant transport pipe is wound is rotated, and the spherical adsorbent contained in the perforated pipe 11 constituting the spacer is gradually moved in the longitudinal direction of the perforated pipe at the middle of the refrigerant transport pipe. In other words, it is relocated to the center in the longitudinal direction.

If the adsorbent is moved to the middle of the refrigerant transport pipe as described above, the SI layer 7 at the middle of the refrigerant transport pipe
Adsorption of gas adhering to SI material in holed tube 11
through the numerous holes 12 of the SI
Evacuation is performed through evacuation passages 8 formed on both sides of the spacer 11 outside and inside the layer 11 .

When the above operation continues and the degree of vacuum reaches a saturated state where the degree of vacuum does not increase any further, that is, when the gas adsorption of the adsorbent reaches a saturated state, the drum rotates to move the saturated adsorbent into the perforated tube 11. Roll it to the end of the refrigerant transport pipe. Then, at the end where the adsorbent has been transferred, heating is performed from the outside of the tube using propane gas or other heating means to heat the adsorbent at a temperature of 80 to 100°C and perform baking to discharge the adsorbed gas. Note that the discharged gas is exhausted to the outside of the tube by a vacuum pump.

When heating is performed from the outside of the refrigerant transport pipe, the end portion of the transport pipe, that is, the part made of metal such as stainless steel, is heated, so there is no problem such as melting of the SI material due to heating.

The adsorbent, whose gas has been discharged and regenerated by baking as described above, is again rolled in the perforated tube 11 by the rotation of the drum and transferred to the middle of the refrigerant transport pipe, where it remains in the SI layer. It absorbs more gas and continues vacuum evacuation work.

In this way, the adsorbent is gas adsorbed by placing it in the center of the refrigerant transport pipe in the longitudinal direction → moved to the end of the transport pipe after being saturated with gas adsorption → baking (gas discharge and regeneration) → redirected to the center of the refrigerant transport pipe. By repeating the cycle of further gas adsorption due to movement, the degree of vacuum in the middle of the refrigerant transport pipe is increased.

In addition, since the conductance for vacuum evacuation is large in evacuation for gas vaporization and separation at the terminal side of the refrigerant transport pipe, the above-mentioned method can be used simply by placing the adsorbent material fixedly on the terminal side of the transport pipe. Although it is possible to obtain a degree of vacuum comparable to the degree of vacuum obtained, it may also be achieved by gradually moving the adsorbent in the longitudinal direction of the tube as described above.

〔Effect of the invention〕

As is clear from the above description, according to the refrigerant transport pipe and evacuation method for the same of the present invention, gas discharge from the SI layer at the longitudinal center of the refrigerant transport pipe, which has been difficult in the past, ie vacuum evacuation. It has become possible to carry out this process efficiently, and it has become possible to increase the degree of vacuum to 1×10 ^-4 Torr or higher at room temperature.

Therefore, gas adsorption from the SI layer in the longitudinal center of the refrigerant transport tube can be sufficiently performed, and the adsorbed gas can be easily discharged, thereby shortening the evacuation time for the SI layer and improving the degree of vacuum. The intended purpose of improvement has been fully achieved and the benefits are great.

[Brief explanation of the drawing]

Fig. 1 is an explanatory cross-sectional view showing the structure of a conventional refrigerant transport pipe, Fig. 2 a is an explanatory cross-sectional view showing an example of the structure of the refrigerant transport pipe according to the present invention, and Figs. 2 b and c are the same as above. FIG. 2 is a cross-sectional explanatory diagram showing a structural example of a spacer used in the transport pipe shown in FIG. In the symbols, 1 is a refrigerant passage, 2 is an inner pipe, 3 is a vacuum insulation layer, 4 is a first middle pipe, 5 is a refrigerant return space,
6 is the second middle pipe, 7 is the SI layer, 8 is the vacuum evacuation space, 9
10 is an outer tube, 10 is a conventional spacer, 11 is a spacer of the present invention (ie, a tube with holes), 12 is a hole, 13 is an adsorbent, and 14 is a spherical cover.

Claims (1)

[Claims] 1. In order to secure a vacuum evacuation space adjacent to the laminated insulation material, a large number of holes are provided that penetrate in the radial direction through a spacer that is arranged in the length direction in contact with the laminated insulation material. What is claimed is: 1. A refrigerant transport pipe comprising a perforated pipe, the perforated pipe containing a spherical adsorbent having an outer diameter smaller than the inner diameter of the perforated pipe. 2. In order to secure a vacuum evacuation space adjacent to the laminated insulation material, the spacer is arranged in the longitudinal direction of the laminated insulation material in contact with the laminated insulation material, and is composed of a perforated tube having a large number of holes passing through it in the radial direction. Then, by rotating a drum around which the refrigerant transport tube is wound up, the spherical adsorbent material is stored in the perforated tube and the spherical adsorbent material has an outer diameter smaller than the inner diameter of the refrigerant transport pipe. is placed in the center of the transport pipe in the longitudinal direction, and the transport pipe is evacuated by evacuation from both ends of the pipe. When the degree of vacuum due to the evacuation reaches saturation, The spherical adsorbent that has adsorbed the gas is moved to the end side of the transport pipe by the rotation of the drum, and is baked to discharge the adsorbed gas, and the regenerated spherical adsorbent is then returned to the drum. A method for evacuation of a refrigerant transport pipe, characterized by moving the refrigerant to the center of the transport pipe by rotation and performing vacuum evacuation.