JPH0544888A - Vacuum heat insulator for high temperature - Google Patents

Abstract

PURPOSE:To provide a vacuum heat insulator for high temperature which is a heat insulting wall in contact with high temperature, whose inside vacuum is maintained at high level despite the influence of such a high temperature and which is capable of high-level heat insulation and easy to be manufactured. CONSTITUTION:An inorganic fiber or inorganic powder 3 which was compressed by a pressure equivalent to the atmospheric pressure against vacuum to the thickness almost the same as heat insulating space of a heat insulating wall 1 is inserted into the heat insulating space of the insulating wall 1. And a synthetic zeolite 4 is maldistributed as a gas absorbent on the inner face on the low-temperature side of the heat insulating wall 1, and inside of the heat insulating wall is sealed to vacuum. By arranging the absorbent at a portion not affected by high temperature, the inside vacuum is maintained at high level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vacuum heat insulator for high temperature.

[0002]

2. Description of the Related Art Conventionally, as a structure of a heat insulating wall for performing high heat insulation, there is known a heat insulating wall in which a heat insulating wall composed of an inner wall and an outer wall is a hermetically sealed space and the inside is densely filled with an inorganic foamed powder and further evacuated. Japanese Patent Publication No. 60-8399). This kind of heat insulating wall can obtain a higher heat insulating effect by the synergistic effect of the vacuum atmosphere inside and the heat insulating effect of the highly densely packed inorganic foamed powder. For example, a wall body with a thickness of about 4 to 5 cm is used. It is possible to insulate between room temperature and the temperature difference of 300-400 ℃.

[0003]

However, since the surface contacting the high temperature side of the heat insulator is exposed to extremely high temperature, the adjacent inner surface portion is also heated to high heat at the same time, and this heat causes gas from the internal filler to be generated. There is a problem in that this outgas lowers the degree of vacuum and the heat insulating effect. As a means for adsorbing such outgas and maintaining a vacuum inside, it is proposed to enclose a getter material inside the heat insulating wall as disclosed in, for example, Japanese Patent Publication No. 2-43945 or 3-32719. Has been done. But,
In the case of performing high-temperature heat insulation at 200 ℃ or more, the effect of this heat causes the release of the adsorbed gas from the getter material, and there is a problem that the effect of maintaining the degree of vacuum cannot be expected so much.

[0004]

In view of the above problems, the present invention is a heat insulating wall which is in contact with a high temperature, and the internal vacuum degree is capable of high-order heat insulation despite the influence of such a high temperature, and is manufactured. The purpose of the present invention is to provide a high-temperature heat insulator that is easy to manufacture.

[0005]

That is, the vacuum insulator for high temperature according to the present invention comprises an inorganic fiber or an inorganic powder compressed at a pressure equal to atmospheric pressure against a vacuum until the heat insulating space of the heat insulating wall has a substantially equal thickness. It is characterized in that it is inserted into the heat insulating space of the heat insulating wall, the gas adsorbent is unevenly arranged on the inner surface of the heat insulating wall on the low temperature side, and the inside of the heat insulating wall is vacuum-sealed.

[0006]

In the present invention, the heat insulating wall to which the present invention is applied has a structure in which the front and back surfaces are heat resistant membranes, for example, stainless steel membranes, and a space between them is a heat insulating closed space. And, as a main structure for heat insulation, the inside of the heat insulating wall is filled with a heat insulating material made of inorganic fibers such as rock wool or inorganic porous powder, and the inside is evacuated. Prior to filling, the material is used by being compressed and hardened at a pressure substantially equal to the difference between vacuum and atmospheric pressure to be solidified. Therefore, after being housed in the heat insulating space, the heat insulating wall is reinforced from the inside by the consolidation force, and the heat is improved and the strength is improved.

Then, a gas adsorbent such as synthetic zeolite is unevenly arranged on the inner surface of the heat insulating wall on the low temperature side, and the inside of the heat insulating wall is vacuum-sealed. In this case, since the synthetic zeolite for adsorbing the gas is arranged on the inner surface of the heat insulating wall on the low temperature side, it is prevented from being exposed to high temperature in combination with the heat insulating effect of the heat insulating wall itself, and re-emission of the adsorbed gas hardly occurs. That is, even if there is residual gas inside the heat insulating wall or outgas released from the reinforcing material or the like in contact with the inner surface on the high temperature side, the gas adsorption ability is maintained and the internal vacuum degree is prevented from lowering.

[0008]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of an embodiment of the present invention, and FIGS. 2 to 4 are a perspective view and a sectional view showing the steps for carrying out the present invention.

Example 1 A stainless steel membrane having a thickness of 0.5 mm was used to form inner and outer walls 1A and 1B.
A plate formed by press-compressing short fibers made of glass fiber having a fiber diameter of 5 μm to 8 μm at 1 kg / cm ² into a container 2 having a heat insulating wall 1 having a thickness of the heat insulating space of 30 mm and molding it into 500 mm × 500 mm × 30 mm. The compression-molded body 3 in the shape of
Inserted from the opening A (FIG. 2) to make a tightly packed state inside, and then arranging synthetic zeolite 4 in layers on the bottom 2A (FIG. 3) of the container 2 to seal the container bottom 2A (FIG. 4). ) The heat insulation container 2 shown in FIG. 1 was obtained.

Example 2 A container 2 having a heat insulating wall 1 was obtained in the same manner as in Example 1 except that the glass fiber mat used in Example 1 was replaced with an inorganic porous silica powder having an average fiber diameter of 5 μm. .

Comparative Example 1 A compression molded body 3 was obtained by uniformly dispersing synthetic zeolite in the glass fiber in Example 1, and the same was filled in the heat insulating wall 1 as in Example 1, and the synthetic zeolite was placed on the bottom. The inside was sealed and vacuumized without uneven distribution to obtain a heat-insulating container. Comparative Example 2 A heat-insulating container was obtained in the same manner as in Comparative Example 2 by mixing the synthetic zeolite in the silica powder in Example 2 in a uniformly dispersed state.

Next, an adiabatic test was conducted on the examples and comparative examples. As for the test conditions, as shown in FIG. 5, a heater H was inserted inside, the opening was closed with a heat insulating lid 5, and the inside was heated to 350 ° C. The external temperature was 20 ° C. When the degree of vacuum (Torr) inside the heat insulating wall 1 was measured, the results shown in FIG. 6 were obtained. As is clear from FIG. 6, in the example, the vacuum degree was drastically reduced until the lapse of 2 days, but thereafter, the vacuum degree was almost returned to the initial state due to the adsorption force of the synthetic zeolite. In the case of No. 2, the degree of vacuum sharply decreased until the lapse of 2 days, and thereafter, the degree of vacuum was gradually decreased, and no recovery phenomenon of the degree of vacuum was observed.

[0013]

As described above, according to the present invention, since the synthetic zeolite serving as the gas adsorbent is unevenly distributed on the inner surface of the low temperature side which is not affected by heat, the gas re-release from the gas adsorbent due to the high temperature is released. Is completely prevented, a decrease in the degree of vacuum inside the heat insulating wall is efficiently prevented, and a stable heat insulating effect is maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a high temperature vacuum heat insulator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a high temperature vacuum heat insulator according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing the manufacturing process of the high-temperature vacuum heat insulator of the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the manufacturing process of the high-temperature vacuum heat insulator of the embodiment of the present invention.

FIG. 5 is an explanatory diagram of test conditions of an example.

FIG. 6 is a graph showing test results of examples and comparative examples.

[Explanation of symbols]

 1 Insulation Wall 2 Container 2A Opening 2B Bottom Part 3 Compression Molded Body 4 Synthetic Zeolite

Claims (1)

[Claims] 1. An inorganic fiber or an inorganic powder compressed at a pressure equal to atmospheric pressure against a vacuum until the thickness of the heat insulating wall is approximately equal to the thickness of the heat insulating wall is inserted into the heat insulating space of the heat insulating wall, and at the same time, gas adsorption is performed. A high-temperature vacuum heat insulator, characterized in that the material is unevenly arranged on the inner surface of the heat insulation wall on the low temperature side, and the inside of the heat insulation wall is vacuum-sealed.