JP2003185353A - Furnace charged gas heating device for electric furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a furnace charged gas heating device for an electric furnace capable of raising a temperature of a charged gas to 100°C or more. <P>SOLUTION: In this device for heating the gas or air charged into the furnace to create the furnace atmosphere of the electric furnace for baking ceramic, a heating element 1 comprising a spiral heat generating part 3 and an electrode terminal 4 taken out from the heat generating part is inserted into a protective tube 7 penetrated through a furnace inner wall 9 in a state of locating the heat generating part inside of the furnace, a gas or air charging tube 5 is inserted in the protective tube 7 toward the heat generating part, the gas or air charged through the charging tube 5 is guided to the spiral heat generating part 3 to be heated, and the heated gas or air is released into the furnace. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas heating device for charging an electric furnace into an electric furnace, and more specifically, to form a predetermined atmosphere inside the electric furnace for firing ceramics, a gas or air having a predetermined component is externally supplied. The present invention relates to a charging gas heating device for heating gas or air in order to prevent adverse effects due to disturbance of temperature distribution in a furnace when charging.

[0002]

2. Description of the Related Art Generally, an electric furnace for firing a ceramic generally needs to be operated by raising the temperature inside the furnace to about 1300 ° C., and for forming an atmosphere inside the furnace in such a high temperature state. When supplying gas or air from the outside,
It is desirable to heat these input gases to a temperature as close as possible to the temperature in the furnace and then to charge the gas into the furnace in order to minimize disturbance of the operating conditions in the furnace and to perform stable furnace operation.

However, conventionally, as a device for heating gas or air to be introduced into an electric furnace for firing ceramics, a metal heater protected by an insulating material is usually used, and in some cases, a metal heater and ceramic heat storage are used. The method of using materials together was also adopted, but since the metal heaters are used in all of them, the heater temperature is 1000 ° C.
However, the temperature of the input gas after heating is 8
The limit was about 00 ° C.

Therefore, the temperature difference between the maximum temperature in the furnace and the input gas temperature is as high as 500 ° C., which is a great problem for the stability of the furnace operating conditions, but a heater that can heat the gas to a higher temperature than this. Neither was it easy to manufacture. The inventors have set the metal heater to a heater temperature of 1
Attempting to raise the temperature of the input gas or the air to 800 ° C. or higher by raising the temperature to about 200 ° C. has resulted in shortening the service life due to the remarkable deterioration of the metal heater, which is not practically applicable.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems in the gas heating device for preheating the gas or air supplied from the outside in order to form the atmosphere inside the electric furnace for firing ceramics. The present invention has been made to solve the problem, and an object thereof is to provide an in-furnace input gas heating device of an electric furnace capable of increasing the input gas temperature to 1000 ° C. or more prior to the input.

[0006]

According to a first aspect of the present invention, there is provided a gas charging apparatus for charging gas in an electric furnace in order to form an atmosphere in the electric furnace for firing ceramics. Which is a device for heating gas or air to be injected into a heating tube, the heating tube having a spirally formed heat generating portion and an electrode terminal taken out from the heat generating portion in a protective tube that penetrates through the inner wall of the furnace. The heat generating part is inserted so that it is located inside the furnace, and the gas or air injection pipe is inserted into the protective pipe toward the heat generating part.The gas or air injected through the injection pipe is formed into a spiral shape. It is characterized in that it is configured so that it is guided to a heat generating part and heated, and gas or air after heating is discharged into the furnace.

According to a second aspect of the present invention, there is provided an in-furnace charging gas heating apparatus for an electric furnace, wherein the heating element is silicon carbide.

[0008] According to a third aspect of the present invention, there is provided an in-furnace charging gas heating apparatus for an electric furnace, wherein the protection tube is made of Al ₂ O ₃ —SiO ₂ -based ceramic, and a gas or air charging tube is provided. Is composed of Al ₂ O ₃ —SiO ₂ -based ceramics.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a resistance heating element having a heating portion formed in a spiral shape is applied. The resistance heating element is preferably silicon carbide.
It becomes possible to heat to a temperature up to about 0 ° C. The gas or air can be efficiently heated by inserting a resistance heating element having a spiral heating element into the protective tube and introducing gas or air between the heating section and the protective tube.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view showing the arrangement of a protective tube and a heating element. The heating element 1 is inserted into a protective tube 7 which is arranged so as to penetrate through the furnace inner wall 9 formed of a heat insulating / heat resistant lining layer, and which is preferably made of Al ₂ O ₃ —SiO ₂ ceramic.

A heating element 1 preferably made of silicon carbide.
Includes a heating portion 3 formed in a spiral shape and an electrode terminal 4 taken out from the heating portion 3, and the heating portion 3 formed in a spiral shape is inserted into the protective tube 7 so as to be on the inside 10 side of the furnace. It On the side opposite to the heat generating portion 3 of the heat generating element 1, a columnar heat generating element is formed into an end portion 2 which is vertically divided into two parts, and an electrode terminal 4 at the tip of the end portion 2 is attached.

The inner diameter of the protective tube 7 is formed to be slightly larger than the outer diameter of the heat generating portion 3 formed in a spiral shape, and the tip of the heat generating portion 3 does not protrude from the tip of the protective tube 7 protruding into the furnace. To be installed. Further, like the protective tube 7, a gas or air injection tube 5 made of Al ₂ O ₃ —SiO ₂ ceramic is inserted from the electrode terminal 4 side into the end portion 2, and the tip of the injection tube 5 is spiral. Shaped heat generating part 3
And reach the vicinity of the boundary of the end 2.

With this configuration, the in-furnace input gas or air introduced from the gas supply port 6 of the input pipe 5 passes through the input pipe 5 and spirally passes between the spiral heating portion 3 and the protective pipe 7. After being efficiently heated, the gas is discharged into the furnace 10 through the gas outlet 8 of the protective tube 7.

[0014]

EXAMPLES Examples of the present invention will be described below. This example shows one embodiment of the present invention, and the present invention is not limited to this.

Example 1 As a silicon carbide heating element having a spiral heating portion, SGR (outer diameter 20 mm, heating portion length 200 mm, end portion 150 mm) manufactured by Tokai High Temperature Industrial Co., Ltd. ) Nikkato mullite tube HB (outer diameter 3
5 mm, inner diameter 28 mm, length 270 mm), and as a gas or air injection pipe, the same Nikkato Mullite Tube HB (outer diameter 12 mm, inner diameter 8 mm, length 200 mm) was used, as shown in FIG. It was installed in.

When a furnace was operated using this input gas heating device and the amount of air input was 40 liters / minute, the gas blowing temperature into the furnace was 1000 ° C. Further, even when the amount of air input was lowered to 20 liters / minute, the gas blowing temperature into the furnace was 1186 ° C., and in each case, the target input gas temperature of 1000 ° C. or higher could be achieved.

Example 2 When this heating device was actually installed in a tunnel furnace for firing a base metal electrode ceramic chip capacitor, and the furnace was operated, the temperature transition in the maximum temperature zone intended to hold at 1350 ° C. was stabilized, Conventionally, the temperature fluctuated by about 20 ° C irregularly during one day, but it was able to be kept within the range of about 5 ° C.

[0018]

According to the furnace heating gas heating apparatus of the present invention, gas heating to a temperature of 1000 ° C. or higher, which cannot be obtained by the conventional apparatus, can be stably obtained. Therefore, the influence of the input gas on the atmosphere temperature in the furnace can be reduced, and stable firing of the ceramic-processed product becomes possible.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a furnace charging gas heating apparatus according to the present invention.

[Explanation of symbols]

1 heating element 2 ends 3 heating section 4 electrode terminals 5 Input pipe 6 gas supply port 7 protection tube 8 gas outlets 9 Inner wall 10 inside the furnace

Claims (3)

[Claims] 1. A device for heating gas or air to be introduced into a furnace for forming an atmosphere in a furnace for an electric furnace for firing ceramics, wherein a spiral pipe is provided on a protective tube arranged to penetrate an inner wall of the furnace. A heating element having a heat-generating portion formed in a shape of a circle and an electrode terminal taken out from the heat-generating portion is inserted so that the heat-generating portion is located inside the furnace, and a gas or air injection pipe is provided in the protective pipe as the heat-generating portion. It is characterized in that it is configured so that the gas or air introduced through the introduction pipe is introduced into the spirally formed heat generating portion to be heated and the heated gas or air is discharged into the furnace. A gas heating device for charging the electric furnace. 2. The in-furnace gas heating device for an electric furnace according to claim 1, wherein the heating element is silicon carbide. 3. The protective tube is made of Al ₂ O ₃ —SiO ₂ -based ceramic, and the gas or air inlet tube is A
l ₂ O ₃ -SiO ₂ based furnace input gas heating apparatus for an electric furnace according to claim 1 or 2, characterized in that they are composed of a ceramic.