JP2022053947A - Heating device and glass manufacturing method - Google Patents

Abstract

To utilize the heat-generating performance of a heating body in a wider range of applications by suppressing the melting loss of the heating body at a contact area with a support body.SOLUTION: A heating device 10 includes a heating body 20 that generates heat due to electrical resistance and a support body 30 on which the heating body 20 is placed and on which the heating body 20 is supported from below. The thermal conductivity of the support body 30 is higher than that of the heat-generating side contact portion 20a, which is a portion of the heating body 20 that is in contact with the support body 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heating device and a method for manufacturing glass using a heating device.

Patent Document 1 discloses a heating device used for manufacturing a semiconductor device, glass, or the like. The heating device of Patent Document 1 includes a long heating element that generates heat due to electric resistance, and a support that supports the heating element from below. In the heating device of Patent Document 1, the heating element and the contact portion of the support with the heating element are formed of a molybdenum disilicate-based ceramic.

International Publication No. 2014/199647

In a conventional heating device, even when the heating element is used at a temperature lower than the maximum operating temperature set for the heating element, the heating element may break due to melting damage at the contact portion with the support. there were. In order to prevent the heating element from breaking due to melting damage, it is conceivable to adjust the heating temperature of the heating element to a low level before use, but in this case, the heat generation performance of the heating element cannot be fully exhibited. There is a problem.

The present invention has been made in view of such circumstances, and an object thereof is to utilize the heat generation performance of the heating element in a wider range by suppressing the melting damage of the heating element at the contact portion with the support. It is in.

The heating device that solves the above problems is a heating device including a heating element that generates heat due to electric resistance and a support on which the heating element is placed and supports the heating element from below, and the heat of the support is provided. The conductivity is higher than the thermal conductivity of the heating side contact portion, which is a portion of the heating element that contacts the support.

The thermal conductivity of the support is, for example, 1.1 times or more the thermal conductivity of the heat-generating side contact portion. The heating element is made of, for example, molybdenum disilicate.
According to the above configuration, heat is easily transferred from the heating element to the support at the contact portion between the heating element and the support, so that the heat is suppressed from staying at the heat generating side contact portion of the heating element. As a result, the local temperature rise of the heat-generating side contact portion of the heating element is suppressed, and melting damage is less likely to occur in the heat-generating side contact portion. As a result, when the heating device is used, the heat generation temperature of the heating element can be increased to the maximum heating temperature or a temperature closer to the maximum heating temperature, and the heat generating performance of the heating element can be utilized in a wider range.

In the heating device, the support preferably supports the heating element by point contact or line contact.
In this case, a large amount of heat can be transferred to the support by increasing the area of the contact portion on the heating side of the heating element.

The glass manufacturing method for solving the above problems is a glass manufacturing method for manufacturing glass by a glass manufacturing apparatus including the above-mentioned heating apparatus, and heating the glass by setting the heat generation temperature of the heating element to 1000 ° C. or higher. Perform processing.

According to the above configuration, the local temperature rise of the heat generating side contact portion of the heating element is suppressed, and melting damage is less likely to occur in the heat generating side contact portion. Therefore, the glass can be stably produced.

According to the present invention, by suppressing the melting damage of the heating element at the contact portion with the support, the heat generating performance of the heating element can be utilized in a wider range.

Explanatory drawing of the heating device. Schematic diagram of glass manufacturing equipment. Explanatory drawing which shows arrangement of a heating element and a support in a simulation. (A) and (b) are graphs showing simulation results.

Hereinafter, an embodiment of the present invention will be described.
As shown in FIG. 1, the heating device 10 includes a heating element 20 that generates heat due to electric resistance, and a support 30 on which the heating element 20 is placed and supports the heating element 20.

The shape of the heating element 20 is not particularly limited, but is preferably rod-shaped. The rod-shaped heating element 20 may be, for example, a linear rod shape, a curved rod shape, or a rod shape in which a linear portion and a curved portion are combined. good. The cross-sectional shape of the heating element 20 may be a circular shape, a polygonal shape, or any other shape.

In FIG. 1, as an example, a heating element 20 having a U-shaped extending rod shape and a circular cross-sectional shape is shown. Electrode terminals 21 for energizing the heating element 20 are provided at both ends of the heating element 20 shown in FIG. 1.

The type of the heating element 20 is not particularly limited, and a known heating element can be used. The heating element 20 is a ceramic heating element made of a conductive ceramic material such as molybdenum dissilicate (MoSi ₂ ), silicon carbide (SiC), tungsten carbide (WC), zirconia (ZrO ₂ ), and carbon (C). The body is mentioned.

The heating element 20 made of the conductive ceramic material may contain a component other than the conductive ceramic material. For example, the heating element 20 made of molybdenum disilicate is composed of 50 to 95% by volume of molybdenum disilicate and 5 to 50% by volume of a silica-based oxide phase or a glass phase. In addition, the heating element 20 composed of molybdenum disilicate may further add, for example, 50% by volume or less of other elements to the total volume of these components, or heat-treat these components. By doing so, it is resistant to high temperatures and atmosphere. Further, even if such a composite material of molybdenum disilicate and other ceramics or glass has a function as a heating element based on molybdenum disilicate, it is included in the heating element 20 composed of molybdenum disilicate. Is done.

The type of the heating element 20 can be appropriately selected according to the heat generation temperature required for the heating device 10. The heat generation temperature required for the heating device 10 is the surface temperature of the heat generation portion of the heating element 20 during use. The heat generation temperature is, for example, 800 ° C. or higher, preferably 1000 ° C. or higher. The heat generation temperature is, for example, 2500 ° C. or lower. In the case of a conventional heating device, when the maximum heating temperature of the heating element is 1000 ° C. or higher, the heating element is likely to be melted and damaged at the contact portion with the support. The maximum heating temperature of the heating element 20 is, for example, the maximum operating temperature set in the heating element 20 by the manufacturer.

The heat generation temperature required for the heating device 10 can be appropriately set according to the heating target. As an example, in the case of the heating device 10 used in the glass manufacturing device, the heat generation temperature is, for example, 1000 to 1800 ° C.

The glass manufacturing apparatus including the heating device 10 is used, for example, in a glass manufacturing method including a step involving a heat treatment for heating the glass. Examples of the glass to be heated in the heat treatment include glass raw materials, molten glass, and once molded glass.

FIG. 2 shows an example of a glass manufacturing apparatus 40 that heat-treats glass. In the glass manufacturing apparatus 40, the heating apparatus 10 is provided on the upper part of the melting furnace main body F to heat the glass raw material M charged into the melting furnace main body F and the molten glass G stored in the melting furnace main body F. Used.

Further, when the glass is heat-treated, the heating temperature of the heating element 20 of the heating device 10 is set to 1000 ° C. or higher. As a result, the glass such as the glass raw material M and the molten glass G can be sufficiently heated, and the heat treatment of the glass can be efficiently performed.

The support 30 is configured such that the heating element 20 is placed on the upper portion thereof to support the heating element 20 from below.
The shape of the support 30 is not particularly limited, and may be any shape such as a rod shape, a plate shape, and a block shape. The shape of the support 30 is preferably such that the contact area with the heating element 20 is small, for example, the shape in which the contact state with the heating element 20 is point contact or line contact.

For example, when the heating element 20 has a circular rod shape in cross section, the support 30 is arranged as a linear rod shape having a circular cross section, and the support 30 is arranged so as to extend in a direction intersecting the heating element 20. Then, the contact state with the heating element 20 becomes point contact. Further, when the heating element 20 has a rod shape having a circular cross section, the support 30 has a flat upper surface such as a rod shape or a flat plate having a polygonal cross section, and the flat upper surface is a mounting surface. When the support 30 is arranged so as to be, the contact state with the heating element 20 becomes line contact.

The support 30 is made of a material having a higher thermal conductivity than the heat conductivity of the heat generating side contact portion 20a, which is a contact portion of the heating element 20 with the support 30. Here, the temperature range for deriving the thermal conductivity of the heating side contact portion 20a of the heating element 20 and the thermal conductivity of the support 30 is not particularly limited, but at a specific temperature within the operating temperature range of the heating element 20. It is preferable to have. It is necessary to make the thermal conductivity of the heat generating side contact portion 20a of the heating element 20 equal to the temperature conditions for deriving the thermal conductivity of the support 30.

The thermal conductivity Y of the support 30 is preferably 1.1 times or more, preferably 1.5 times or more, the thermal conductivity X of the heat-generating side contact portion 20a of the heating element 20, for example. Further, the thermal conductivity Y of the support 30 is, for example, 5 times or less the thermal conductivity X of the heat generating side contact portion 20a of the heating element 20.

Further, for the thermal conductivity Y of the support 30, for example, the difference (= YX) from the thermal conductivity X of the heating side contact portion 20a of the heating element 20 is preferably 10 W / mK or more, preferably 30 W / mK. It is more preferable that it is mK or more. Further, the above difference is, for example, 100 W / mK or less.

Examples of the material constituting the support 30 include silicon carbide (SiC), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), molybdenum disilicate (MoSi ₂ ), tungsten carbide (WC), and carbon (C). Examples thereof include ceramic materials such as mullite, zircone, and materials applied to known supports such as refractories such as alumina-based electric cast refractories.

The support 30 is configured to have a property that the thermal conductivity is higher than the thermal conductivity X of the heat-generating side contact portion 20a of the heating element 20 and the heat-resistant temperature is higher than the heat-generating temperature of the heating element 20. The thermal conductivity and heat-resistant temperature of the support 30 vary not only with the material constituting the support 30, but also with physical properties such as the density of the support 30.

The number and arrangement of the supports 30 are not particularly limited, and any number and arrangement may be used as long as the heating element 20 can be supported from below. In FIG. 1, as an example, a case where five straight rod-shaped supports 30 are arranged in parallel at equal intervals is shown. Each support 30 is fixed to a holding member (not shown).

Next, the operation of this embodiment will be described.
Even when used in a conventional heating device at a temperature lower than the maximum heat generation temperature, the major cause of melting damage of the heating element at the contact portion with the support is heat conduction from the heating element to the support. be. Heat does not transfer from the heating element to the support at the contact portion between the heating element and the support, and the heat stays at the heat generating side contact portion of the heating element, so that the temperature of the heating side contact portion rises locally. If the temperature of the heat-generating side contact portion exceeds the maximum heat-generating temperature set for the heating element, the heat-generating side contact portion will be melted.

In the heating device 10 of the present embodiment, a support 30 having a higher thermal conductivity than the heating side contact portion 20a of the heating element 20 is used. As a result, heat is easily transferred from the heating element 20 to the support 30 at the contact portion between the heating element 20 and the support 30, and the heat is suppressed from staying at the heating side contact portion 20a of the heating element 20. As a result, the local temperature rise of the heat-generating side contact portion 20a of the heating element 20 is suppressed, and melting damage is less likely to occur in the heat-generating side contact portion 20a.

As shown in FIG. 3, five rod-shaped supports 30 having a circular cross section are arranged in parallel and at equal intervals, and a rod-shaped heating element 20 having a circular cross section extending linearly is placed on the support 30. In the state, the distribution of the surface temperature of the heating element 20 when the heating element 20 was heated was simulated. The conditions of the simulation are as follows.

Heat generation temperature: 1600 ℃
Thermal conductivity of the contact part of the heating element at 1600 ° C: 15W / mK
Thermal conductivity of the support at 1600 ° C.: 1W / mK or 30W / mK
FIG. 4 shows the result of the simulation. As shown in FIG. 4A, when the thermal conductivity of the support 30 is 1 W / mK, which is lower than the thermal conductivity of the heat generating side contact portion 20a of the heating element 20, the heat generating side contact portion of the heating element 20 The temperature rises locally at 20a (positions A to E). On the other hand, as shown in FIG. 4B, when the thermal conductivity of the support 30 is 30 W / mK, which is higher than the thermal conductivity of the heat generating side contact portion 20a of the heating element 20, the heat generating side of the heating element 20 is generated. The temperature drops locally at the contact portion 20a.

Next, the effect of this embodiment will be described.
(1) The heating device 10 includes a heating element 20 that generates heat due to electric resistance, and a support 30 on which the heating element 20 is placed and supports the heating element 20 from below. The thermal conductivity Y of the support 30 is higher than the thermal conductivity X of the heat-generating side contact portion 20a, which is a portion of the heating element 20 that contacts the support 30.

According to the above configuration, heat is easily transferred from the heating element 20 to the support 30 at the contact portion between the heating element 20 and the support 30, so that the heat stays in the heating side contact portion 20a of the heating element 20. It is suppressed. As a result, the local temperature rise of the heat-generating side contact portion 20a of the heating element 20 is suppressed, and melting damage is less likely to occur in the heat-generating side contact portion 20a. As a result, when the heating device 10 is used, the heat generation temperature of the heating element 20 can be raised to the maximum heat generation temperature or a temperature closer to the maximum heat generation temperature, and the heat generation performance of the heat generator 20 can be utilized in a wider range. can.

(2) The thermal conductivity Y of the support 30 is 1.1 times or more the thermal conductivity X of the heat generating side contact portion 20a, or the difference between the thermal conductivity Y and the thermal conductivity X of the support 30 ( = YX) is 10 W / mK or more. In this case, the effect of (1) above can be obtained more remarkably.

(3) The support 30 supports the heating element 20 by point contact or line contact.
In this case, the area of the heating side contact portion 20a of the heating element 20 can be increased. Therefore, more heat can be transferred to the support.

In addition, this embodiment can be changed and carried out as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
The number of support-side contact portions, which are contact portions with the heating element 20 in one support 30, may be singular or plural. When a plurality of support-side contact portions are provided on one support 30 and the support-side contact portions are made of a conductive material such as silicon carbide, between adjacent support-side contact portions. It is preferable to provide an insulating structure for insulating the silicon. As the insulating structure, for example, an insulating portion made of an insulating material may be provided between adjacent support-side contact portions.

Hereinafter, the above-described embodiment will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these. The thermal conductivity described below is the thermal conductivity at 400 ° C.

(Example 1)
A heating device provided with a heating element and a support having the shape and arrangement shown in FIG. 1 was produced. As the heating element, a heating element having a thermal conductivity of 15 W / mK composed of molybdenum disilicate was used. As the support, a support made of silicon carbide (Hexory (registered trademark) manufactured by Saint-Gobain Co., Ltd.) was used. The thermal conductivity and heat resistant temperature of the support are as shown in Table 1. The thermal conductivity ratio shown in Table 1 indicates the ratio (Y / X) of the thermal conductivity Y of the support to the thermal conductivity X of the heating element.

Next, the heating element of the manufactured heating device was energized so as to have a heating temperature of 1600 ° C., and after maintaining the energized state for 72 hours, the energization to the heating element was stopped. By visually observing the state of the heating element after the energization was stopped, it was confirmed whether or not the heating element was broken due to melting damage. The results are shown in Table 1.

(Comparative Examples 1 to 3)
The test was carried out in the same manner as in Example 1 except that the support was changed to the following support. The results are shown in Table 1.

Comparative Example 1: Zirconia (ZR-11 manufactured by Nikkato Corporation)
Comparative Example 2: Baked Zircon (ZETA-AH manufactured by Yotai Co., Ltd.)
Comparative Example 3: Electroformed Alumina (SCIMOS-M manufactured by Saint-Gobain M.)

表１に示すように、発熱体の熱伝導率よりも低い熱伝導率の支持体を用いた比較例１～３では、発熱体に溶損による折れが確認された。一方、発熱体の熱伝導率よりも高い熱伝導率の支持体を用いた実施例１では、発熱体に折れは確認されなかった。

As shown in Table 1, in Comparative Examples 1 to 3 using a support having a thermal conductivity lower than that of the heating element, it was confirmed that the heating element was broken due to melting. On the other hand, in Example 1 using a support having a thermal conductivity higher than that of the heating element, no breakage was confirmed in the heating element.

10 ... Heating device 20 ... Heating element 20a ... Heating side contact part 30 ... Support 40 ... Glass manufacturing device

Claims (5)

A heating device including a heating element that generates heat due to electric resistance and a support on which the heating element is placed and supports the heating element from below.
A heating device characterized in that the thermal conductivity of the support is higher than the thermal conductivity of the heat generating side contact portion, which is a portion of the heating element that comes into contact with the support. The heating device according to claim 1, wherein the thermal conductivity of the support is 1.1 times or more the thermal conductivity of the heat-generating side contact portion. The heating device according to claim 1 or 2, wherein the heating element is made of molybdenum disilicate. The heating device according to any one of claims 1 to 3, wherein the support is a heating element that supports the heating element by point contact or line contact. A method for manufacturing glass, wherein the glass is manufactured by a glass manufacturing apparatus including the heating apparatus according to any one of claims 1 to 4.
A method for producing glass, which comprises performing a heat treatment for heating glass by setting the heat generation temperature of the heating element to 1000 ° C. or higher.

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