JP2607417B2 - Multi-layer vacuum insulation method and insulated double tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer vacuum heat insulating method and a heat insulating double pipe used for a pipe for transferring a low-temperature or high-temperature fluid or the like and a storage container.

[0002]

Related Art For example, liquid oxygen, transporting pipe of low-temperature liquefied gas such as liquid nitrogen is generally made inside and outside the double tube, the space portion with the interposition of the heat insulating member in the space portion of the double pipe < Manufactured or constructed by the so-called multi-layer vacuum insulation method with vacuum insulation. This vacuum-insulated double pipe is usually made of stainless steel inner and outer pipes with appropriate space to form a double pipe, and the outer peripheral surface of the inner pipe is wound in multiple layers with a mylar material made of aluminum-deposited resin film. In addition, a space is maintained by interposing a spacer made of a material having low thermal conductivity such as a synthetic resin, and the space is evacuated to form a vacuum heat insulating layer.

[0003] In a low temperature liquefied gas storage container, relatively large ones are manufactured by the powder vacuum insulation method, while medium and small ones are usually manufactured by the same multi-layer vacuum insulation method as described above. It is.

[0004]

The above-mentioned multi-layer vacuum insulation method is generally called super-insulation. By interposing a multi-layer mylar material in a vacuum space, the multi-layer vacuum heat insulation method has the largest influence on heat conduction. Heat loss can be greatly reduced, and the effect is remarkable.
Therefore, since the effect is relatively easy to implement in combination with the effect, most of the low-temperature liquefied gas transfer piping is provided by the heat insulating means.

[0005] However, this heat insulating means has a problem, especially in heat insulating piping, because a resin film on which aluminum is deposited is used as a mylar material. As is well known, in vacuum insulation, the degree of vacuum decreases with time because outgassing occurs from the metal wall surface. This is accompanied by a decrease in the heat insulation effect, so that it is necessary to repeatedly evacuate to maintain the desired vacuum heat insulation, but various measures have been taken since the operation becomes complicated.

In general, as a measure against degassing in vacuum heat insulation, means for forcibly removing degassing in advance by heating (baking) during a vacuum suction step is used. However, the mylar material generally used in the multilayer vacuum heat insulation method is a resin film on which aluminum is deposited as described above, so that the heat treatment is not performed,
Even if it is carried out, the heating temperature is low, and the effect is of course small.
For this reason, conventionally, the inner peripheral surface of the outer tube and the outer peripheral surface of the inner tube have been subjected to plating treatment for the purpose of reflection and prevention of degassing, but at present, satisfactory measures have not been reached. Usually, since this kind of heat insulation method takes measures against extremely low temperature fluid such as liquid oxygen, the degassing is condensed by the cooling of the low temperature liquefied gas during transfer or storage, and the vacuum heat insulation effect is maintained. In the case of piping, such an effect cannot be expected because the transfer is of course intermittent.

[0007] The present inventors have studied to eliminate the disadvantages without impairing the effect of the above-mentioned multi-layer vacuum heat insulation method, and as a result, the degassing process of this kind of heat insulation method has been significantly reduced. The present invention has been achieved by focusing on the heat treatment which was considered to be non-existent. That is, the present invention provides a multi-layer vacuum adiabatic method, in which degassing by heating minimizes outgassing over time to maintain the vacuum adiabatic effect for a long time, and transfer or store high-temperature fluid. It is an object of the present invention to provide a multi-layer vacuum insulation method and a heat insulation double tube capable of withstanding the above problems.

[0008]

In order to achieve the above object, a multi-layer vacuum heat insulation method according to the present invention comprises the steps of:
Multi-layer vacuum adiabatic method in which vacuum is created by vacuum suction
The mylar material was subjected to a brilliant treatment on at least one side.
Use a stainless steel sheet and add a suitable number to the stainless steel sheet.
Of the stainless steel by the burr at the time of the drilling
The plates are stacked without being in close contact with each other, and degassing is performed by heating when vacuuming the space . Further, the insulated double pipe according to the present invention is an inner and outer double pipe .
Mylar material is wound around the outer surface of the tube in multiple layers, and the inner tube and the outer tube
In the insulated double tube in which the space portion is evacuated, the space
While holding the part with a spacer made of ceramic,
The mylar material has a surface having at least one surface subjected to a glittering treatment.
An appropriate number of small holes are drilled in a stainless steel sheet,
The stainless steel sheets are alternated by burrs formed during drilling.
And the space portion is vacuum-absorbed
The gas is degassed by heating at the time of drawing .

[0009]

According to the present invention, since the mylar material is made of a heat-resistant stainless steel thin plate, it is possible to perform heat treatment (baking) at a high temperature. Therefore, deterioration of vacuum insulation due to degassing can be prevented. Degassing process
Occasionally, stainless steel with an appropriate number of small holes made of mylar material
The thin steel plates adhere to each other by burrs formed when drilling
Since the wire is wound without being wound, voids and small holes
It becomes a path, and degassing is efficiently exhausted.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the multilayer vacuum heat insulation method according to the present invention will be described below. The multilayer vacuum insulation method according to the present embodiment includes:
Multiple layers to prevent radiant heat in the space inside and outside dual structure
The Mylar material Ru is interposed is obtained by a stainless steel sheet. This mylar material can be used in recent years as a lead frame material in the semiconductor technology field,
It has a thickness of about 12 μm, and at least one surface thereof is subjected to a luminous treatment by annealing or the like.

The mylar material is provided with an appropriate number of small holes. The small holes are formed in the space of the inner / outer double structure due to the ease of vacuum suction and minute burrs generated when the holes are drilled. When the Mylar material is multi-layered, the layers do not adhere to each other and serve as a spacer material.

Such a mylar material is laminated on the outer peripheral surface of the inner tube, the inner cylinder or the inner tank by winding or the like. This mylar material
Has a relationship with the heat insulating effect, but is about 30 layers. Next, when vacuuming the space of the inner and outer dual structure
Degas by heating . The heating source is optional, but it is usually performed by applying a burner flame or the like to the outer surface of the outer tube, outer cylinder or outer tub and the inner surface of the inner tube, inner cylinder or inner tub . Is stopped.

Next, an embodiment of a heat insulating double pipe according to the present invention will be described with reference to the drawings. The insulated double pipe is made of a stainless steel outer pipe 1 and an inner pipe 2 which are usually made of stainless steel.
The space 3 is held between the outer tube 1 and the inner tube 2 while being held by the pacer 4.
A mylar material 5 made of a stainless steel thin plate having at least one bright surface treated on at least one side thereof is formed on the outer peripheral surface of the inner tube 2 in a multi-layer by winding or the like into, for example, about 30 layers.
Layer. The Mylar material 5, for example, a thickness of about 12μm, can be used, also drilled an appropriate number of small holes
The burrs formed at the time of drilling
It is wound without. The space 3 is used for processing during vacuum suction.
Degassed by heat .

Further, the conventional spacer is made of a resin having a low thermal conductivity as described above and is formed of a square frame, and the four corners of the frame are connected to the contact points with the inner surface of the outer tube. However, the spacer 4 of the present embodiment is made of ceramic, and the shape thereof is, as shown in FIG. 1, as shown in FIG. At the same time, the four corners, which are the points of contact with the inner surface of the outer tube 1, are sharpened to reduce the loss due to heat conduction.

By making the mylar material 5 a stainless steel thin plate in this way, it is possible to perform a baking treatment at a much higher temperature than before. In other words, in the case of a conventionally used aluminum vapor-deposited resin film, the heat-resistant temperature is about 80 ° C.
However, according to the present example, the heat-resistant temperature of the mylar material 5 was about 750 ° C., and the heat-resistant temperature of the spacer 4 was about 1200 ° C., and a satisfactory effect was obtained by baking at about 250 ° C. In addition, at the time of degassing processing,
When a stainless steel sheet with an appropriate number of small holes is drilled
Are wound without being in close contact with each other
Therefore, voids and small holes formed by burrs serve as flow paths, and degassing occurs.
Efficiently discharged.

[0016]

As is apparent from the above description, the present invention has solved the inconvenience relating to outgas generation in the multi-layer vacuum heat insulation method and the heat insulation double pipe. That is, since the baking treatment at a high temperature can be performed, the generation of outgas due to aging can be suppressed as much as possible, so that a vacuum heat insulating effect can be expected for a long time, and there is no particular need for a means for suppressing outgas in the inner and outer tubes. There is. In addition, the stainless steel sheet used in the present invention has recently been used in large quantities as a lead frame in the semiconductor field and can be obtained relatively inexpensively, so that the implementation cost is lower than when a conventional aluminum vapor-deposited resin film is used. It is advantageous.
In addition, at the time of degassing, an appropriate number of small
A stainless steel sheet with holes
It is wrapped without sticking to each other,
Degassing is efficiently discharged by the voids and small holes
It is.

In general, it cannot be denied that the vacuum insulation method has been developed for low-temperature fluids or atmospheres, including superinsulation. Therefore, a conventional heat insulation method using super insulation has not been considered for transferring a high-temperature fluid in the field of petroleum refining and the like. However, as described above, the method of the present invention can withstand high-temperature fluids, and thus has a large effect in combination with its heat insulating performance.

[Brief description of the drawings]

FIG. 1 is a sectional front view of an insulated double pipe of the present invention.

FIG. 2 is a cross-sectional side view of the AA line tube of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer tube, 2 ... Inner tube, 3 ... Space part, 4 ... Spacer, 5
… Mylar material

Claims (2)

(57) [Claims] 1. A mylar material is frequently provided in a space having a double internal / external structure.
The space is evacuated by vacuum suction with the
In the multi-layer vacuum insulation method,
At least one side is made of bright stainless steel sheet
Then, an appropriate number of small holes are drilled in the stainless steel thin plate,
Laminated stainless steel sheets without close contact due to burrs when drilling
And a degassing process by heating at the time of vacuum suction of the space portion . 2. A mylar material is provided on the outer peripheral surface of the inner tube of the inner / outer double tube.
Wrapped around multiple layers and evacuated the space between the inner and outer tubes
In the insulated double pipe, the space is made of ceramic.
While holding with a spacer, the mylar material is less
Both stainless steel sheets with a bright surface on one side
And the stainless steel sheet is perforated.
Wound without sticking to each other due to burrs formed at the time of hole
And the space is degassed by heating during vacuum suction.
A heat-insulated double pipe that has been treated .