JPH11335113A - Electric furnace for graphitization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durabilities of electrodes and supporting parts to hold and to insulate the electrodes by suppressing their thermal degradation to a minimum. SOLUTION: Plural sets of the electrodes 9a and 9b opposingly set between a carbon powder feed opening 4 and a graphite powder recovery port 7 in a furnace body 1 with a graphitization zone 8 between are installed so as to at least partially face to the interior of the furnace body 1, an electric current can be sent with staggering the timings of each set of the electrodes 9a and 9b. The electrodes 9a and 9b are attached to the inner ends of a heat transfer member 12 passing through the inside and outside of the furnace body 1 and the heat transfer member 12 can be cooled from its outer ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a graphitizing electric furnace.

[0002]

2. Description of the Related Art Conventionally, carbon powder has been industrially manufactured by heat-treating carbon powder in an inert atmosphere at a temperature of about 3000 ° C. or higher to graphitize the carbon powder. .

[0003] Graphite electric furnaces such as Acheson furnaces are used for the production of this type of graphite powder, and the carbon powder used as the material is indirectly heated by Joule heat generated when electricity is supplied to coke. Is graphitized. In general, the existing graphitizing electric furnace was designed to manufacture graphite powder in a batch system, so the productivity was poor,
Therefore, there has been a demand for the development of a graphitizing electric furnace capable of producing graphite powder by continuously heating carbon powder.

[0004] On the other hand, as a continuous graphitizing electric furnace proposed at the present time, for example, a carbon powder is filled between a pair of graphite electrodes, and both electrodes are moved while moving the carbon powder. By energizing between the graphite electrodes and heating the carbon powder with Joule heat, the graphite electrodes themselves also generate heat with Joule heat and actively use as heaters to maintain the inside of the furnace at about 3000 ° C. or higher. Are continuously graphitized.

[0005]

However, in such a conventional graphitizing electric furnace, electrodes facing each other, such as graphite electrodes, are generated on the carbon powder 2 by a current flowing through these electrodes. In order to reach a high temperature due to Joule heat, it is necessary to pay attention to the fusing of each electrode and a connection part of a current supply circuit for supplying a current to these electrodes. There has been a problem that thermal quality deterioration and durability of materials and furnace walls are remarkably deteriorated, the frequency of replacement thereof is increased, and maintenance management cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the temperature of each of electrodes such as a graphite electrode and a metal electrode is set to 2 points.
By cooling so as to be suppressed to 500 ° C. or less and 1000 ° C. or less, it is possible to prevent the electric connection between each electrode and the current supply circuit from being blown, and to prevent electrode materials, the furnace wall of the furnace body, and the furnace wall It is another object of the present invention to obtain a graphitizing electric furnace capable of improving the durability of a supporting member for supporting and insulating the electrode by minimizing thermal deterioration.

[0007]

In order to achieve the above-mentioned object, the present invention relates to a method for supplying electricity to a carbon powder filled in a furnace main body through an electrode disposed opposite to the furnace main body so as to sandwich the carbon powder. In a graphitized electric furnace in which the carbon powder is graphitized by the heat generated by the carbon powder, an electrode is attached to an inner end of a heat conductive member penetrating inside and outside the furnace body, and the heat conductive member is moved from the outer end thereof. It is configured to be cooled.

Therefore, according to the present invention, the temperature of the electrode can be lowered to a desired temperature, and the deterioration of the thermal quality of the electrode and the insulating support member for insulating and supporting the electrode can be suppressed. Further, it is possible to prevent the fusing and the deterioration of the strength of the connection portion between the electrode and the electric supply circuit beforehand, and to improve the durability of the entire high current supply portion.

Also, by passing the electrode through the inside and outside of the furnace body and cooling it from the outer end side, the electrode itself can be quickly and efficiently inserted without any intermediate member. Allow cooling.

A cooling member having a refrigerant jacket for circulating cooling water or refrigerant gas is connected to the outer ends of the electrodes and the heat conducting member, thereby forcibly and directly cooling the electrodes. For example, the temperature can be maintained at 1000 ° C. or less for a metal electrode and 2500 ° C. or less for a graphite electrode.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a graphitizing electric furnace according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA of FIG. 1. In the figure, reference numeral 1 denotes a water-cooled furnace main body. In the center of the upper part of the furnace main body 1 is provided a carbon powder inlet 4 through which a carbon powder 2 as a raw material can be charged by a screw conveyor 3. In the center of the lower part of the furnace main body 1, a graphite powder recovery port 7 for recovering the graphite powder 5 after the carbon powder 2 has been heat-treated by a screw conveyor 6 is provided. The inside of the furnace main body 1 is kept in an atmosphere of an inert gas such as an argon gas or a vacuum, and is isolated from the outside air.

Here, the furnace main body 1 in the example shown in FIG.
The body is formed in a cylindrical shape and the upper portion is formed in a conical shape with an axis O connecting the carbon powder input port 4 and the graphite powder recovery 7 in the longitudinal direction as a center, and the bottom is flat. It is formed in a simple disk shape.

As for the water cooling structure of the furnace body 1, well-known water cooling means may be employed, and a wall portion of the furnace body 1 may be a water cooling jacket, or a number of flow paths may be formed in the wall portion. What is necessary is just to be able to circulate and supply cold water to these water cooling jackets and flow paths.

Further, in this embodiment, an appropriate halfway position between the carbon powder input port 4 and the graphite powder recovery port 7 in the furnace main body 1 is defined as a graphitized region 8 (cross hatched portion in the figure). And On the inner wall of the body of the furnace body 1 at the same height position as the graphitized region 8, a conductive material such as copper facing the diametrical direction of the body, that is, facing the graphitized region 8 therebetween. Electrodes 9a, 9b made of material
Are arranged in a plurality of annular sets. Also, each set of electrodes 9
A current control device 10 and a power supply 11 are connected to a and 9b, which are energized at different timings.

As shown in FIG. 3, the electrodes 9a and 9b are attached to the inner end of a rod-shaped heat conducting member 12 penetrating the inside and outside of the furnace wall 1a of the furnace body 1. Specifically, a mounting hole H is provided in the center of one side of each of the electrodes 9a and 9b, and inside the mounting hole H, the inner end of the heat conductive member 12 made of a conductive metal such as a copper alloy. Are fitted by press fitting or the like. In the case where the electrodes 9a and 9b are graphite electrodes, their surfaces after forming are rough, so that a substantially sufficient holding force can be obtained by such fitting.

The heat conducting member 12 is hermetically supported on the furnace wall 1a by a supporting member 13 made of a material having high heat resistance and electrical insulation such as ceramic. That is, by using the heat conductive member 12, it is possible to guide a large current to the electrodes 9a and 9b such as graphite electrodes while ensuring airtightness with respect to the furnace wall 1a. And
At the outer end of the heat conducting member 12, a mounting flange 12a is integrally provided. The mounting flange 12a is attached to the mounting flange 15a of the cooling member 15 having the refrigerant jacket 14.
Are abutted as shown in the figure and are closely connected by fasteners such as bolts and nuts. In the coolant jacket 14, cooling water, coolant gas such as NH3 and the like are forcibly circulated by a pump means (not shown).

The material of the furnace body 1 itself may be an insulating material such as industrial hard plastic or ceramics, and the power source 11 may be AC or DC.

Next, the operation of this embodiment will be described. First, the carbon powder 2 is charged into the furnace main body 1 from the carbon powder input port 4, and current is sequentially supplied to the electrodes 9a and 9b of each set at a different timing by the current control device 10, and as shown in FIG. All the current flowing between the electrodes 9a and 9b flows through the graphitized region 8. For this reason,
The current density in the graphitized region 8 is higher than its outer periphery, and the amount of heat generated by Joule heat increases. On the other hand, in the vicinity of the furnace main body 1 having a water cooling structure, it is cooled by water cooling. As a result, the carbon powder 2 filled in the furnace main body 1 is locally heated to a high temperature only in the graphitized region 8 and is graphitized.

Therefore, if the graphite powder 5 graphitized in the graphitized area 8 is recovered from the graphite powder recovery port 7 while the new carbon powder 2 is charged from the carbon powder input port 4, the graphite can be continuously obtained. Powder 5 can be produced.

At this time, the carbon powder 2 in the graphitized region 8 generates heat by Joule heat by energization and becomes graphitized. Moreover, the surrounding carbon powder 2 stays in the furnace main body 1 surrounding the flow of the carbon powder 2 or the graphite powder 5 from the carbon powder input port 4 to the graphite powder recovery port 7, while gradually graphitizing from the inside, It functions as a heat insulator for the furnace body 1 side. Since the furnace body 1 contains only the carbon powder 2 as a raw material, there is no room for impurities to be mixed into the graphite powder 5 recovered from the graphite powder recovery port 7.
Only the pure graphite powder 5 can be reliably recovered. In addition, burnout of the furnace body 1 and the electrodes 9a and 9b is reduced, and the durability of the furnace body 1 and the electrodes 9a and 9b can be improved.

Further, since there is no room for impurities to be mixed into the graphite powder 5 recovered from the graphite powder recovery port 7 as described above, only the pure graphite powder 5 can be recovered satisfactorily. The stability of the quality of the powder 5 can be greatly improved.

During the production of the graphite powder, a large current is supplied to the electrodes 9a and 9b facing each other from the power supply 11 via the current control device 10, the cooling member 15, and the heat conduction member 12. . At this time, each electrode 9a, 9
b is heated to a high temperature by the Joule heat generated by the carbon powder 2 itself as described above.

On the other hand, since the cooling member 15 is cooled by the refrigerant supplied so as to always circulate in the refrigerant jacket 14, this cold heat is transmitted through the heat conducting member 12 which is in close contact with the cooling member 15. Further, the electrodes 9a,
9b. Therefore, these electrodes 9a, 9b
Temperature rise is suppressed, and quality deterioration due to high-temperature heating can be avoided together with the heat conduction member 12.

Further, since the temperature rise of the heat conducting member 12 itself is prevented as described above, the heat conduction to the supporting member 13 and the furnace wall 1a of the furnace body 1 to which the supporting member 13 is attached is hindered. When it is made of an insulating material such as an industrial hard plastic as described above, it is possible to prevent quality deterioration due to high-temperature heating.

Further, a cable end through which a current flows between the electrodes 9a and 9b is connected to the heat conducting member 12 or the cooling member 15, and the cable end is brazed or fixed with a fastener. Accidents such as melting of a part or cutting of an electric circuit due to thermal deformation can be avoided beforehand.

In the above description, the case where the heat conducting member 12 and the cooling member 15 are connected as separate bodies has been described. However, it is also optional to use a structure in which these are integrally formed from the beginning. However, in this case, it is important to prevent the refrigerant jacket 14 from entering the furnace body 1. This is to prevent the refrigerant in the refrigerant jacket 14 from vaporizing due to the high-temperature heating in the furnace body 1.

FIG. 4 shows another embodiment of the present invention. This is an electrode 9 such as a graphite electrode or a metal electrode.
a and 9b themselves are penetrated and supported on the furnace wall 1a of the furnace body 1 via a support member 13 having electrical insulation and heat resistance. Therefore, one end of each of the electrodes 9a and 9b faces so as to protrude into the furnace main body 1, and a cooling member 15 having a refrigerant jacket 14 is attached to an outer end which is the other end. Specifically, the outer ends of the electrodes 9a and 9b are fixed to the mounting holes J formed in the cooling member 15 by a method such as press fitting.

Most of the cooling member 15 is guided along a small space with respect to the furnace wall 1a, as shown in the figure. Therefore, it does not protrude greatly outside the furnace wall 1a.

In this embodiment, since the electrodes 9a, 9b are directly cooled by the cooling member 15, each electrode 9a, 9b is cooled.
The cooling efficiency of the furnace 9b and the furnace wall 1a is further enhanced.

[0030]

As described above, according to the present invention, the electrode is attached to the inner end of the heat conducting member penetrating into and out of the furnace body, and the heat conducting member is cooled from the outer end thereof. Therefore, the furnace body can be attached to the furnace wall while ensuring sufficient sealing performance, and the electrodes in the furnace body can be reliably cooled via the heat conducting member.
As a result, there is obtained an effect that thermal quality deterioration and breakage of not only the electrode itself but also the heat conductive member, the support member for the heat conductive member, the furnace wall, and the connection portion of the current supply cable can be sufficiently suppressed.

Further, since a cooling member having a cooling jacket is integrally or separably connected to the outer end of the heat conducting member, the cooling medium flowing through the cooling jacket is used to make the heat conductive member and the electrode. Can be cooled more efficiently, and in particular, the effect that the temperature of the electrode can be surely controlled to an arbitrarily selected level or less can be obtained.

Further, the electrode penetrates into and out of the furnace body,
Since cooling is performed from the outer ends of these electrodes, it is possible to apply cold heat directly to the outer ends of the electrodes, thereby further increasing the temperature of not only the electrodes themselves, but also the heat conducting members and supporting members thereof. It can be suppressed efficiently. By connecting a cooling member having a cooling jacket to the outer end of the electrode, the electrode itself and various components related thereto can be more efficiently cooled by using a refrigerant flowing through a refrigerant jacket. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a graphitizing electric furnace according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of the graphitizing electric furnace in FIG.

FIG. 3 is an enlarged cross-sectional view showing an electrode mounting structure in FIG.

FIG. 4 is an enlarged sectional view showing another mounting structure of the electrode in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Furnace main body 2 ... Carbon powder 3, 6 ... Screw conveyor 4 ... Carbon powder input port 5 ... Graphite powder 7 ... Graphite powder recovery port 8 ... Graphitized area 9a, 9b ... Electrode 10 ... ... Current control device 11 ... Power supply 12 ... Heat conduction member 13 ... Support member 14 ... Refrigerant jacket 15 ... Cooling member

Claims (4)

[Claims] An electric power is supplied to an electrode arranged opposite to a furnace body so as to sandwich the carbon powder in the furnace body so as to sandwich the carbon powder, and the carbon powder is graphitized by heat generation of the carbon powder by the energization. In the graphitized electric furnace, the electrode is attached to an inner end of a heat conducting member penetrating inside and outside of the furnace main body, and the heat conducting member is cooled from an outer end thereof. . 2. The graphitizing electric furnace according to claim 1, wherein a cooling member having a refrigerant jacket is integrally or separably connected to an outer end of the heat conducting member. 3. An electric power is supplied to an electrode, which is disposed opposite to the furnace body so as to sandwich the carbon powder, with respect to the carbon powder filled in the furnace body, and the carbon powder is graphitized by heat generation of the carbon powder due to the energization. In the graphitized electric furnace, the electrode is penetrated into and out of the furnace main body, and is cooled from an outer end of the electrode. 4. A cooling member having a cooling jacket is continuously provided at an outer end of said electrode.
2. The graphitizing electric furnace according to 1.