JP2601589B2 - High vacuum insulation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum insulated double pipe,
The present invention relates to a high-vacuum insulation method for vacuum insulation between the inner and outer shells of a vacuum-insulated double shell such as a vacuum-insulated double container.

[0002]

2. Description of the Related Art Generally, a vacuum insulated double pipe is used as a liquid transport pipe for transporting an ultra-low temperature fluid such as liquid nitrogen from the viewpoint of heat insulation. As a method of vacuum-insulating between the inner and outer pipes of the vacuum-insulated double pipe, a multilayer vacuum insulation method (super insulation) is generally employed. In this multilayer vacuum insulation method, an aluminum foil 1 as a vacuum insulation material is provided on the outer peripheral surface of an inner tube 11 of a vacuum insulation double piping.
3 and dexita paper (asbestos paper) 14 are wound alternately in multiple layers (about 25 to 50 layers). Tube 1
The space between the inner tube 2 and the inner tube 11 is evacuated to a high vacuum (below 10 ^-4 Torr). FIG. 5 shows an enlarged view between the inner pipe 11 and the outer pipe 12 of the vacuum insulated double pipe thus obtained. In the figure, the space between the inner tube 11 and the outer tube 12 is in a vacuum state.
And dexter paper 14 are provided in an alternating multilayer winding layer.

[0003]

However, in the above method, the aluminum foil 13 is used as a vacuum heat insulating material.
When the dexter paper 14 is wound in multiple layers, the dexter paper 14 itself is rich in water absorbency. While exposed to a high humidity atmosphere, the dexter paper 14 absorbs moisture in the air and becomes highly water-containing. In such a high water content state, even if the vacuum evacuation is performed, the moisture causes resistance to the vacuum evacuation, so that the evacuation requires a long time (for example, 480 hours or more). In such a case, prior to the evacuation, the entire double pipe is heated to evaporate the moisture absorbed by the dexter paper 14. As a result, the time required for evacuation can be somewhat reduced. However, aluminum has a low melting temperature.
The temperature can only be raised to this point. In this case, it takes a long time to discharge H ₂ , O ₂ , N ₂ , moisture and the like adsorbed and occluded on the inner and outer stainless steel tubes, and at the same time, quickly absorbs the water absorbed by the dexter paper 14. The fact is that it is not possible to evaporate and evaporate, so that the above-mentioned heating does not shorten the time sufficiently.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-vacuum heat insulating method capable of shortening the time required for evacuation and maintaining heat insulating performance for a long time. And

[0005]

In order to achieve the above object, a high vacuum heat insulating method according to the present invention comprises a non-aluminum metal foil having a ceramic particle spotted layer formed on one side by thermal spraying. Is wound in multiple layers on the outer peripheral surface of the inner shell with the inside facing, and the outer shell is put on the outer periphery of this multilayer wound layer to seal between the outer shell and the inner shell. The space between the inner shell and the inner shell is evacuated.
Here, the ceramic particle spotted layer means a layer formed by adhering ceramic particles at a predetermined interval to each other, and each ceramic particle is attached to a metal foil at a predetermined interval from an adjacent ceramic particle. Have been.

[0006]

According to the high vacuum heat insulating method of the present invention, a non-aluminum metal foil having a ceramic particle spotted layer formed on one side is used as a vacuum heat insulating material, and the above-mentioned ceramic particle spotted layer is directed inward. In this state, it is wound in multiple layers around the outer peripheral surface of the inner shell, leaving a space around the outer shell, covering the outer shell to seal between the outer shell and the inner shell, and in this state, a vacuum is applied between the outer shell and the inner shell. Exhaust. In this case, since the ceramics particle spotted layer has much less water absorption than the dexter paper, even if the metal foil is wound in a high-humidity atmosphere, it can be applied to vacuum evacuation. No time is required. Further, in the ceramic particles spotted layer,
Since the ceramic particles are attached in a dotted state, when the non-aluminum vacuum heat insulating material is wound in multiple layers and evacuated, the gap between the ceramic particles serves as a flow path for air, and the evacuation is efficiently performed. Done. In addition, since the ceramic particles are bonded to the surface of the non-aluminum metal foil by thermal spraying, the ceramic particles can easily adhere to the surface of the non-aluminum metal foil in a dome shape, and a wide flow path can be secured as the air flow path. In addition, the non-aluminum metal foil and the ceramic particles are inorganic substances, and the compatibility is good, so the bonding between the non-aluminum metal foil and the ceramic particles is strengthened, and even if the evacuation power is strong, the non-aluminum metal The ceramic particles do not peel off from the foil.

Next, the present invention will be described in detail.

In the present invention, the term "non-aluminum metal foil" refers to various metal foils other than aluminum foil (may be about 20 to 50 μm if it can be wound). In particular, as a non-aluminum metal foil, the melting temperature is high like stainless steel foil, copper foil or nickel foil,
It is preferable to use a metal foil having good radiation efficiency.

In general, the ceramic particle-dotted layer formed on one side of the metal foil moves the thermal spray nozzle at right angles to the moving direction while moving the band-shaped metal foil in the longitudinal direction. It is formed by reciprocating in the direction in which the ceramic particles are sprayed. In the ceramic particles spotted layer thus formed, the diameter of the ceramic particles spotted is usually 5 to 50 μm.
m (therefore, the thickness of the dot layer is substantially the same as that), and the interval between the particles is set to about 50 to 500 μm. Preferably, the particle size of the ceramic particles is 1
0-30 μm and the particle spacing is 100-200 μm.

Next, the present invention will be described in detail based on embodiments.

[0011]

FIG. 1 shows an example of a vacuum insulated double pipe according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a vacuum insulated double pipe, and a vacuum heat insulating material 6 is provided between an inner pipe 2 and an outer pipe 3 thereof.
Is wound in multiple layers. This vacuum heat insulating material 6 is made of a non-aluminum metal foil 4 shown in FIG. In this embodiment, a stainless steel foil is used as the non-aluminum metal foil 4. The stainless steel foil 4 has a higher melting temperature than the aluminum metal foil, and can withstand heating at a high temperature of 350 to 400 ° C. As shown in FIGS. 3 and 4, the stainless steel foil 4 has a grain size of 50 ± 5 on one side (back side).
A dotted layer 5 (particle interval 100 ± 10 μm) consisting of ceramic particles 5 a of μm is formed by thermal spraying. The constituent materials of the ceramic particle spotting layer 5 include forsterite (2MgO.SiO ₂ ), magnesia (Mg
Particles such as O) and alumina (Al ₂ O ₃ ) are used.

The vacuum insulation between the inner tube 2 and the outer tube 3 of the vacuum insulation double piping 1 using the vacuum insulation material 6 is performed as follows. That is, the vacuum heat insulating material 6 is wound in multiple layers around the outer peripheral surface 2a of the inner tube 2 for flowing an ultra-low temperature fluid such as liquid nitrogen. In this case, the ceramic particle spotted layer 5
Is turned inward. Next, the outer tube 3 is covered with a space in the outermost layer of the laminate, and the space between the inner tube 2 and the outer tube 3 is sealed. Next, in this state, the space between the inner pipe 2 and the outer pipe 3 is evacuated (2h) to a high vacuum (below 10 ^-4 Torr) from the exhaust pipe 7. Reference numeral 8 denotes a filter attached to the exhaust pipe 7.

[0013]

As described above, the high vacuum heat insulating method of the present invention uses a non-aluminum metal foil having a ceramic particle spotted layer formed on one side as a vacuum heat insulating material. Has low water absorption,
Even if the metal foil is applied in a high humidity atmosphere, evacuation does not require a long time. Further, as described above, since the ceramics particles are provided on the non-aluminum metal foil as the vacuum heat insulating material, the metal foil does not melt even when the vacuum evacuation is performed at a high temperature. H ₂ , O ₂ , N _{2 and the} like stored in the inner and outer stainless steel tubes constituting the heavy shell can be discharged in a short time. The ceramics particle spotted layer is not formed by densely coating the ceramics powder,
It is formed by roughly attaching ceramic particles,
Voids are formed between the particles. Therefore, when the vacuum heat insulating material is wound in multiple layers and evacuated, the air gap serves as a flow path for air, so that evacuation can be performed efficiently. In addition, since the ceramic particles are bonded to the surface of the non-aluminum metal foil by thermal spraying, the ceramic particles can easily adhere to the surface of the non-aluminum metal foil in a dome shape, and a wide flow path can be secured as the air flow path. In addition to the fact that the non-aluminum metal foil and the ceramic particles are inorganic substances and have good compatibility,
The bonding between the non-aluminum metal foil and the ceramic particles is strengthened, and the ceramic particles are not peeled from the non-aluminum metal foil even if the evacuation power is strong.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a vacuum insulated double pipe according to one embodiment of the present invention.

FIG. 2 is a perspective view of a non-aluminum metal foil constituting a vacuum heat insulating material.

FIG. 3 is a sectional view of a vacuum heat insulating material.

FIG. 4 is a perspective view showing the vacuum heat insulating material as viewed from below.

FIG. 5 is an enlarged view of a conventional example between an inner tube and an outer tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum insulated double piping 2 Inner tube 3 Outer tube 4 Non-aluminum metal foil 5 Ceramics particle point layer 6 Vacuum heat insulating material

Claims (2)

(57) [Claims] 1. A ceramic particle spotted layer is sprayed on one side.
The non-aluminum metal foil formed by the above is wound in multiple layers on the outer peripheral surface of the inner shell with the ceramic particle spotted layer facing inward, and then the outer shell is put on the outer shell of the multilayer wound layer to form an outer shell. A high-vacuum insulation method characterized by sealing between the inner shell and evacuating between the outer shell and the inner shell in that state. 2. The high vacuum insulation method according to claim 1, wherein the non-aluminum metal foil is a stainless steel foil, a copper foil or a nickel foil.