JPH0738800Y2 - Vacuum insulation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a structure in which the outer circumference of a cryogenic liquid transfer pipe or storage container is kept cold by a vacuum heat insulating layer, and in particular, heat rays are blocked in the vacuum heat insulating layer. The present invention relates to a vacuum heat insulating structure in which there is no problem even if the inside of the vacuum heat insulating layer is baked in providing the shielding material.

[Prior Art] A transfer pipe or a storage container for transferring a cryogenic fluid such as liquid helium is formed by covering the outer periphery of the transfer pipe or the storage container with a vacuum heat insulating layer in order to keep the cryogenic liquid cool. The vacuum heat insulating layer is provided with a shielding material such as a vapor deposition mylar (vapor deposition polyester film) for blocking heat rays from the outside to suppress radiative heat transfer.

[Problems to be solved by the invention] By the way, in order to improve the heat insulating performance of the vacuum heat insulating layer, it is necessary to bake the inner wall of the vacuum heat insulating layer to perform degassing, but the temperature during baking is 300 ° C. However, if a material having a low melting point such as a polyester film is used as the shielding material, there is a problem that the material is melted by heat during baking. Therefore, when a shielding material is provided on the vacuum heat insulating layer, baking is not substantially performed and a high degree of vacuum cannot be obtained. Further, when trying to maintain a high degree of vacuum by baking, the shielding material is not provided, so that the heat ray There is a problem that cannot stop the intrusion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vacuum heat insulating structure in which a shielding material is provided on the vacuum heat insulating layer and baking can be performed well.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms a vacuum heat insulating layer on the outer periphery of a cryogenic liquid transfer pipe or a storage container and provides a shielding material in the vacuum heat insulating layer. In the vacuum insulation structure,
In the vacuum heat insulating layer, a plurality of shielding sheets each having an aluminum vapor deposition layer formed on an insulating sheet made of glass fiber are provided to form a shielding material, and then the inside of the vacuum heat insulating layer is baked to be formed.

[Operation] According to the above configuration, the heat-resistant temperature becomes good and the temperature at the time of baking is sufficiently endured by providing a multilayer vacuum insulation layer with a shielding sheet in which an aluminum vapor deposition layer is formed on an insulating sheet made of glass fiber. Therefore, a vacuum heat insulating layer having a high degree of vacuum can be formed, and heat rays can be excellently blocked.

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

FIG. 1 is a sectional view of the vacuum heat insulating structure of the present invention, and FIG. 2 is an enlarged perspective view of the shielding sheet shown in FIG.

First, in FIG. 2, the shielding sheet 1 is formed by forming an aluminum vapor deposition layer 3 on an insulating sheet 2 made of glass fiber (for example, glass fiber paper manufactured by DEXTER). This insulating sheet 2 has a thickness of several μ, and the aluminum vapor deposition layer 3 has a thickness of about 500.
It is formed to a thickness of angstrom.

Now, in FIG. 1, 4 is a transfer pipe for liquid helium 5,
An outer tube 7 for forming the vacuum heat insulating layer 6 is provided on the outer circumference thereof. Located in the vacuum heat insulating layer 6 on the transfer pipe 4 side,
The shielding sheet 1 is provided in multiple layers so as to cover the outer periphery of the transfer tube 4, and the shielding material 8 is formed. The shielding sheet 1 is provided such that the insulating sheet 2 faces the transfer tube 4 side and the aluminum vapor deposition layer 3 faces the outer tube side, and for example, 40 layers are stacked or provided at appropriate intervals.

After the shielding sheet 1 is provided, the inside of the vacuum heat insulating layer 6 is evacuated and heated to be baked to adjust the degree of vacuum to 10 ⁻⁵ to
rr or more. During this baking, the temperature is 300
Although the temperature is up to 350 ° C., the insulating sheet 2 of the shielding sheet 1 is formed of glass fiber and thus exhibits sufficient heat resistance. Further, during baking, degas from the outer wall surface of the transfer pipe 4 is appropriately exhausted through the space between the shielding sheets 1. In this case, degassing can be smoothly exhausted by forming an exhaust hole in the shielding sheet 1.

Next, the operation of the above embodiment will be described.

If liquid helium 5 is flowing in the transfer tube 4, its temperature is 4K, while if the outer circumference of the outer tube 7 is room temperature, the temperature difference between the outer tube 7 and the transfer tube 4 is about 270 ° C. Good heat insulation can be achieved by the heat insulation layer 6. Further, the heat rays from the outer tube 7 to the transfer tube 4 are shielded by the aluminum vapor deposition layer 3 of the shielding sheet 1, and the heat input to the liquid helium 5 can be blocked.

In the above embodiment, the transfer pipe 4 is described as an example, but the same applies to the storage container. Further, the shielding member 8 has been described in the example in which 40 layers of the sheet 1 are stacked, but this is set according to the heat input condition, and the number may be more or less than this. Further, when the shielding sheets 1 are stacked, a large number of dimples may be formed on the insulating sheet 2 so that the dimples can form a gap between the shielding sheets 1 at the time of stacking.

[Effects of the Invention] As is clear from the above description, the present invention exhibits the following excellent effects.

(1) By providing the shielding sheet in which the aluminum vapor deposition layer is formed on the insulating sheet made of glass fiber in the vacuum heat insulating layer, the heat resistance temperature becomes good and the temperature at the time of baking can be sufficiently endured.

(2) Sufficient baking can be performed to form a vacuum heat insulating layer having a high degree of vacuum, and at the same time, heat rays can be blocked well.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
It is a detailed perspective view of the shielding sheet of a figure. In the figure, 1 is a shielding sheet, 2 is an insulating sheet, 3 is an aluminum vapor deposition layer, 4 is a transfer tube, 6 is a vacuum heat insulating layer, and 7 is an outer tube.

Claims (1)

[Scope of utility model registration request] 1. A vacuum heat insulating structure in which a vacuum heat insulating layer is formed on the outer circumference of a transfer pipe or a storage container for a cryogenic liquid and a shielding material is provided in the vacuum heat insulating layer. A vacuum heat insulation structure characterized by forming a shielding material by providing a plurality of shielding sheets each having an aluminum vapor deposition layer formed on the sheet to form a shielding material, and then baking the inside of the vacuum heat insulation layer.