JPH11322318A - Electric furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric furnace to reduce the operating cost through efficiently recovering a specified gas blown into the furnace body. SOLUTION: This electric furnace is designed to treat a feedstock powder charged into the furnace body 1 under heating in a graphitizing zone (heating zone) 6 and withdraw the resulting graphite powder from the furnace body 1, and is provided with a gas feed means 12 for blowing a specified gas into the interior of the furnace body 1 and exhaust nozzles for discharging the specified gas from the furnace body 1; and the exhaust nozzles is made up of a 1st nozzle 13 through which the specified gas is discharged from the furnace body 1 before it comes to the graphitizing zone 6 and 2nd nozzles 14, 15 through which the specified gas is discharged from the furnace body 1 after it passes through the zone 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric furnace for producing a powder such as graphite powder, and more particularly to an electric furnace capable of efficiently recovering a predetermined gas supplied inside a furnace body and improving the efficiency of the recovered predetermined gas. The present invention relates to a device that can be used effectively and can reduce operating costs.

[0002]

2. Description of the Related Art Generally, in order to industrially produce a powder such as a graphite powder, a raw material powder such as a carbon powder is heat-treated at, for example, about 3000 to 3500 ° C. in an inert atmosphere to graphitize the raw material powder. It is done by doing. As a device used for this heat treatment, a conventional device is disclosed in Japanese Patent Application Laid-Open No. 7-252.
No. 726, Japanese Patent Publication No. 3-330, Patent No. 257
An Acheson furnace as described in US Pat. No. 9561 or the like is used.

[0003]

However, the Acheson furnace employs a batch-type manufacturing process in which a raw material powder is charged into a case, then heated to be graphitized, cooled, and then the graphite powder is taken out of the case. To do so, it has the following problems. The basic unit of electric power is large, and the power supply equipment is also large, resulting in high costs. It takes a long time to cool the graphite powder, resulting in poor productivity. It is not suitable for small-lot production. It takes time and effort to fill the raw material powder into the case, and the working environment is deteriorated by dust and the like generated during the work. Since the raw material powder is heated by the conduction of the heating material filled in the case and the heat conduction, the heating efficiency is poor, and there is a problem of contamination of the raw material powder from the case.

In order to cope with such a problem, the raw material powder is introduced from the upper part of the furnace main body, heated while the raw material powder descends to graphitize, and the graphite powder is continuously taken out from the lower part of the furnace main body. A graphitizing electric furnace is conceivable. In this graphitizing electric furnace, it is necessary to set the inside of the furnace main body to a predetermined gas atmosphere in order to prevent the burning of the raw material powder. In this case, it is necessary to efficiently recover the predetermined gas blown into the furnace main body, to reliably discharge the impurity gas generated during heating of the raw material powder from the furnace main body, and to effectively use the recovered predetermined gas. However, it is desired to reduce operating costs.

The present invention has been made in view of such problems, and efficiently recovers a predetermined gas blown into a furnace body together with an impurity gas, and reuses the recovered predetermined gas to reduce operating costs. It is an object of the present invention to provide a graphitizing electric furnace capable of reducing the temperature.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is to heat a raw material powder charged into a furnace main body in a heating area, and to take out the produced powder from the furnace main body. An electric furnace, comprising: gas supply means for blowing a predetermined gas into the furnace main body; and a discharge nozzle for discharging the predetermined gas from the furnace main body. The first to be discharged from the main body
A technique including a nozzle and a second nozzle that discharges a predetermined gas from the furnace body after passing through the heating area is employed. In this electric furnace, gas that has not passed through the heating area is recovered from the first nozzle, and gas that has passed through the heating area is recovered by the second nozzle.
Since the gas is recovered from the nozzles, the gas recovered from each nozzle can be processed by a specific processing apparatus, thereby reducing costs required for gas processing and reducing operating costs.

According to a second aspect of the present invention, in the electric furnace according to the first aspect, a technique in which a plurality of second nozzles are arranged along a flow direction of a predetermined gas is applied. In this electric furnace, gas that cannot be recovered by the second nozzle on the upstream side is discharged to the second nozzle on the downstream side.
Since the gas is recovered by the nozzle, the predetermined gas that has passed through the heating area can be reliably and efficiently discharged from the furnace body.

The invention according to claim 3 is the invention according to claim 1 or 2
In the electric furnace, a technique of forming a circulation path of the predetermined gas is applied so that the predetermined gas discharged from the first nozzle is blown into the furnace main body by the gas supply means. In this electric furnace, since the predetermined gas discharged from the first nozzle is blown into the furnace main body by the gas supply means, the operation cost is reduced by reusing the predetermined gas.

According to a fourth aspect of the present invention, in the electric furnace according to the third aspect, a technique is employed in which a heat exchanger is interposed in a circulation path to exchange heat between a temperature management fluid supplied to the furnace body and a predetermined gas. Is done. In this electric furnace, the temperature control fluid supplied to the furnace body is heated by the heat exchanger, so that a predetermined gas is used as a heat source for heating the fluid, thereby eliminating the need for a heating device and reducing costs. I'm trying.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view showing an electric furnace according to the present invention. This electric furnace has a rigid structure and is a graphitizing electric furnace for producing graphite powder.
The furnace body 1 is connected to a raw material powder supply unit (not shown) via an upper inlet 2 and a graphite powder (product powder) recovery unit (not shown) is connected to a lower part via a tubular member 3. Longitudinal electrodes 4 and 5 are provided on opposing side walls, respectively.
Is attached. In the graphitizing electric furnace, a portion above the electrodes 4 and 5 of the furnace body 1 is defined as a preheating zone a, a portion including the graphitized region 6 between the electrodes 4 and 5 is defined as a heating zone b, and a portion below the electrodes 4 and 5 is defined as a heating zone b. Is a cooling / discharge zone c.

As shown in FIG. 1, the furnace body 1 is formed in such a shape as to be narrowed toward the lower part, thereby increasing the cooling efficiency. However, whether or not the lower part is narrowed in this manner is optional. It is. Furnace body 1 may have a circular or square horizontal cross section, and may further include preheating zones a,
A cooling means such as water cooling (liquid cooling) or air cooling (gas cooling) may be provided corresponding to either the heating zone b or the cooling and discharging zone c.

As a means for supplying the raw material powder, a screw conveyor, a belt conveyor, a turntable or the like for continuously supplying the raw material powder at a predetermined flow rate is used. Is set. In addition, the raw material powder to be charged includes a powdery material and a granular material, and can be graphitized when heated at a high temperature, and has conductivity in a heating temperature range. A precursor or the like is used.

As a collecting means, a turntable, a screw conveyor, or a belt conveyor for continuously cutting the graphite powder sent from the tubular member 3 is used, and the amount of the graphite powder taken out per hour is set by the driving speed of the turntable. Thereby, the residence time of the raw material powder (graphite powder) inside the furnace main body 1 is adjusted.

As shown in FIG. 2, the electrodes 4 and 5 are mounted on the opposite side walls of the furnace main body 1 via insulating materials 7 and 8 corresponding to the graphitized area 6 of the heating zone b. Is connected to the power supply 9. Further, curved plate-shaped insulating materials 10 and 11 are attached to the inner wall of the furnace main body 1 extending over the electrodes 4 and 5. These insulating materials 7, 8, 10, 11 prevent the electric current from short-circuiting through the furnace body 1.

When a current is applied between the electrodes 4 and 5 (for example, 50 V, 1000 A), the raw material powder (graphite powder) generates heat by itself with Joule heat corresponding to the specific resistance.
An elliptical heating region (graphitized region 6) at 500 ° C. to 3500 ° C. is formed and graphitized in this region. Incidentally, the heat source in the preheating zone a is obtained by heat conduction from the heating zone b. However, the raw material powder in the preheating zone a also functions as a heat insulating layer that restricts heat dissipation from the heating zone b.

The arrangement of the electrodes 4 and 5 is not limited to being arranged at the same horizontal level as shown in FIG. 1 or symmetrically arranged with respect to the center of the furnace body 1 as shown in FIG.
They may be arranged in a shifted state. Further, a plurality of sets of electrodes are arranged to face each other,
A configuration may be adopted in which any one set of electrodes is successively energized at predetermined time intervals by switching including 5. With this configuration, the graphitized region 6 is formed from an elliptical shape to a substantially circular shape.

Returning to FIG. 1, the intake 3a of the tubular member 3
Are disposed immediately below the graphitized region 6. The position of the inlet 3a is determined by the inside of the furnace body 1 shown by the dotted line in FIG. Is determined in consideration of the angle of repose of the raw material powder (graphite powder). However, the position of the inlet 3a can be set arbitrarily, and may be arranged in the cooling / discharge zone c, for example, on the bottom surface of the lower end of the furnace body 1.

Further, the graphitizing electric furnace is provided with gas supply means 12 for blowing a predetermined gas into the furnace main body 1. The gas supply means 12 blows a predetermined gas through the tubular member 3 toward the graphitized region 6 in the furnace main body 1. As a gas to be supplied, a gas that does not hinder graphitization of the raw material powder, for example, a nitrogen gas or an argon gas containing no oxygen is used.

The means for blowing gas into the furnace body 1 is not limited to the use of the tubular member 3, and a gas blowing nozzle may be provided at a lower portion of the furnace body 1, for example. Further, the blowing position may be set not in the vicinity of the graphitized region 7 but in the cooling / discharge zone c to promote the cooling of the cooling / discharge zone c by gas blowing. By blowing gas into the furnace main body 1 in this manner, it is possible to set a predetermined pressure so that air does not enter the inside of the furnace main body 1.

The furnace body 1 is provided with a discharge nozzle for collecting a predetermined gas. As shown in FIG. 1, the discharge nozzle is located near the inlet 3a of the tubular member 3 (heating zone b).
And a first nozzle 13 for discharging the predetermined gas from the furnace body 1 before the predetermined gas passes through the graphitization region 6, and a predetermined gas which opens to the upper part of the heating zone b and the preheating zone a. And second nozzles 14 and 15 for discharging from the furnace main body 1 after passing through the region 6.

The first nozzle 13 and the second nozzle 1
Each of the pipes 4, 15 is provided at equal intervals over the circumference of the side wall of the furnace body 1, and the pipes 16, 17, 1
8 is connected. However, whether or not to use these annular tubes 16 and the like is optional. In addition, the second nozzles 14 and 15
Although the predetermined gas is collected at two points along the flow direction of the predetermined gas, the present invention is not limited to this. The predetermined gas may be collected at three or more points along the flow direction.

The annular pipe 16 is connected to the tubular member 3 through a circulation path 19. That is, the gas discharged from the first nozzle 13 is sent from the annular pipe 16 to the tubular member 3 via the circulation path 19 by driving the fan 20. In addition,
The predetermined gas blown from the tubular member 3 is the graphitized region 6
Because it does not pass through, it does not contain impurity gases and can be reused.

A heat exchanger 21 is provided in a part of the circulation path 19. The heat exchanger 21 heats the temperature management fluid (for example, water) sent from the supply source 22 to a predetermined temperature. The heated fluid is supplied to the furnace body 1 and used for keeping the furnace body 1 warm, and prevents dew condensation inside the furnace body 1 when the operation is stopped. On the other hand, the predetermined gas that has passed through the heat exchanger 21 is appropriately cooled.

Whether the circulation path 19 is formed or whether the temperature management fluid is heated by the heat exchanger 21 is optional. The heat exchanger 21 can be used as a heat source for heating other fluids. Effective use may be achieved. You. Further, the temperature management fluid is not limited to be sent from the supply source 22, and may be sent from the furnace body 1 to the heat exchanger 21 again. Further, a temperature management fluid may be used for cooling the furnace body 1.

The annular pipes 17 and 18 are connected to gas processing systems 23 and 24, respectively. That is, the gas discharged from the second nozzle 14 is driven by the fan 25 so that
After being heated by the heater 26 from the heater 7, it is processed by a processing device 27 such as a combustion device or a coagulation pot (oiling device), and is discharged to the atmosphere from a discharge portion 28 such as a chimney. Similarly,
The gas discharged from the second nozzle 15 is supplied from the annular pipe 18 to the heater 30 and the processing device 31 by driving the fan 29.
Is released from the discharge section 32 to the atmosphere. Heater 26,
Numeral 30 is for heating the exhaust gas so as not to be oiled or solidified during the discharge, and in particular, the exhaust gas from the upper second nozzle 15 has passed through the preheating zone a,
The temperature is somewhat low, and it is preferable to appropriately heat the heater 30 in order to prevent oiling and the like.

Since the gas that has passed through the graphitized region 6 contains an impure gas (for example, CmHn gas, etc.), these gas processing systems 23 and 24 appropriately process the impure gas components. In the illustrated example, the gas processing systems 23 and 24 are provided for each of the second nozzles 14 and 15, but the present invention is not limited to this.
15 Gases from both may be treated.

In the course of heating the raw material powder, an impurity gas (for example, CmHn gas or the like) is generated from the raw material powder by thermal decomposition or the like, and the CmHn gas is condensed and liquefied when the temperature decreases, and the preheating zone a This causes the raw material powder to be suspended on the shelf. However, the gas blown into the furnace main body 1 from the tubular member 3 is configured to be heated by passing through the graphitization region 6, and the gas is recovered by the second nozzles 14, 15 above the graphitization region 6. Thereby, the impurity gas can be discharged out of the furnace main body 1 without being condensed.

As a result, the formation of tar-like substances and solids due to the condensation of the impurity gas is prevented, the hanging of the shelves is effectively suppressed, and the lowering of the raw material powder to the heating zone b is made smooth. Further, the impurity gas is prevented from solidifying and adhering to the wall surface in the low temperature portion near the inner wall of the furnace main body 1, and the inner wall of the furnace main body 1 is prevented from being stained. In addition, the gas supplied to the furnace body 1 passes through the tubular member 3 to suppress the cooling of the graphite powder passing through the tubular member 3 and the hanging of the shelves in the tubular member 3. Promotes fluidization of graphite powder.

Next, the operation of the graphitizing electric furnace configured as described above will be described. In the graphitizing electric furnace according to the present invention, the graphitizing treatment is continuously performed without storing a large amount of the raw material powder prepared in the preceding step. First, the raw material powder sent from the supply means at a predetermined flow rate is supplied from the inlet 2 to the furnace body 1.
The raw material powder is lowered in the furnace main body 1 by cutting the graphite powder from the tubular member 3 at a predetermined flow rate by driving the collecting means together. The temperature of the raw material powder at the time of charging is room temperature, but is not limited thereto, and the raw material powder may be heated by the supply means.

When a predetermined current and voltage are applied between the electrodes 4 and 5, the raw material powder itself is heated in the heating zone b by Joule heat according to the specific resistance of the raw material powder. In addition, the input raw material powder is supplied to the preheating zone a.
Since the preheating is performed by the heat conduction from the heating zone b, even if it is non-conductive at the charging stage, a material that becomes conductive by preheating can be used.

In addition, powders generally have low thermal conductivity. Therefore, since the raw material powder itself performs a heat insulating function, external heat is radiated to the outside of the furnace main body 1, while internal heat is difficult to escape, and as a result, the graphitized region 6 has a temperature of 2500 ° C. to 3 ° C.
It will be kept at a temperature of 500 ° C. However, the temperature of the graphitized region 6 can be appropriately set according to the size of the furnace main body 1, a change in current or voltage between the electrodes 4 and 5, the moving speed of the raw material powder in the furnace main body 1, and the graphitized region 7 Can be set similarly.

While being efficiently preheated in the preheating zone a, the raw material powder supplied to the preheating zone a falls with the passage of time in accordance with the amount of the graphite powder cut out by the recovery means. During the passage, it is heated and graphitized. Thereafter, the graphite powder is taken into the tubular member 3 from the inlet 3a, cooled while passing through the tubular member 3, cut out by the collecting means, and sent to another device or the like.

As described above, while the raw material powder is continuously charged into the furnace main body 1 from the charging port 2 by the supply means, the graphite powder formed in the graphitized region 6 is continuously recovered by the recovery means via the tubular member 3. Is taken out. In such a process, the predetermined gas blown into the furnace main body 1 from the tubular member 3 is taken into the first nozzle 13 before reaching the graphitization region 6, and is again transferred from the tubular member 3 through the circulation path 19 to the furnace main body 1. It is blown into 1.

The gas that has passed through the graphitization region 6 is taken into the second nozzle 14 as a carrier gas for the impurity gas, and is discharged to the atmosphere after the impurity gas is processed by the gas processing system 23. Further, the gas that cannot be recovered by the second nozzle 14 is taken into the second nozzle 15, and is similarly released to the atmosphere after the impurity gas is processed by the gas processing system 24. In addition, by suppressing the condensation of the impure gas by the high-temperature gas that has passed through the graphitization region 6, it is possible to prevent the raw material powder from hanging on the shelves and to contaminate the inner wall of the furnace body 1 with the contaminant of the impure gas. To prevent

In this graphitizing electric furnace, the raw material powder is taken out of the furnace body as the graphite powder in the graphitizing region 6 while descending inside the furnace body 1, so that the raw material powder is supplied by the supply means. High quality graphite powder can be efficiently and continuously taken out by the recovery means while being continuously charged, and a continuous production process of graphite powder with high productivity can be realized without storing the raw material powder for a long period of time. Furthermore, since the continuous production process is used, the power consumption is small (about one third of the conventional furnace), the power supply equipment is small, and the cost can be reduced.

Further, the entire apparatus is compact and can be easily adapted to small-quantity production. Even if the operation is stopped due to a trouble during the operation, the damage is small and the operation can be restarted quickly. A case to fill the raw material powder like the Acheson furnace is not required, and there is no problem of contamination from the case,
Generation of dust at the time of filling and discharging the case is reduced, and a favorable working environment can be maintained. The charging of the raw material powder into the furnace body 1 and the removal of the graphite powder can be mechanized, and the automation of the apparatus can be easily performed.

Further, since the residence time of the raw material powder in the graphitization region 6 is set by adjusting the supply amount of the raw material powder and the recovered amount of the graphite powder, the residence time required for graphitization can be easily set by the supply amount of the raw material powder. Thus, optimization of production efficiency in a continuous manufacturing process can be reliably performed with simple control.

Further, since the intake 3a of the tubular member 3 is arranged near the graphitized region 6, the graphitized region 6, ie, the graphite powder heat-treated in the desired temperature region is efficiently taken into the tubular member 3. By taking it out of the furnace body 1, the quality can be made uniform, and the graphite powder is appropriately cooled while passing through the tubular member 3, so that the subsequent processing of the graphite powder taken out of the furnace body 1 can be performed. It will be easier.

By the way, in the furnace body 1 shown in FIG. 1, the graphite powder outside the tubular member 3 stays without being discharged as it is.
It prevents graphite powder from contaminating foreign materials and also functions as a heat insulating material. Further, the shapes, combinations, and the like of the respective constituent members shown in the above-described embodiment are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention. Furthermore, the illustrated one is a graphitizing electric furnace for producing graphite powder, but the electric furnace according to the present invention can also be applied to a powder firing furnace for metal or conductive ceramics.

[0040]

As described above, in the electric furnace according to the first aspect, the gas not passing through the heating area is recovered from the first nozzle, and the gas passing through the heating area is recovered from the second nozzle. In addition, the gas collected from each nozzle can be processed by a specific processing apparatus, so that the cost required for gas processing can be reduced and the operating cost can be reduced.

In the electric furnace according to the present invention, the gas which cannot be recovered by the second nozzle on the upstream side is recovered by the second nozzle on the downstream side. Can be discharged from

In the electric furnace according to the third aspect, since the predetermined gas discharged from the first nozzle is blown into the furnace main body by the gas supply means, the gas consumption is reduced by reusing the predetermined gas, and the operating cost is reduced. Can be achieved.

In the electric furnace according to the fourth aspect, since the temperature control fluid supplied to the furnace main body is heated by the heat exchanger, the heating apparatus is provided by using a predetermined gas as a heat source for heating the fluid. Operation costs can be reduced by making energy unnecessary, such as by using waste heat for raising the temperature of the fluid. Moreover, since the predetermined gas is cooled by the heat exchanger, it is easy to handle the predetermined gas to be reused.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 4, 5 electrode 6 Graphitization area (heating area) 12 Gas supply means 13 1st nozzle (discharge nozzle) 14, 15 2nd nozzle (discharge nozzle) 19 Circulation path 21 Heat exchanger

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenichi Nishi 1 Shinnakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawajima-Harima Heavy Industries, Ltd. Inside the Yokohama Engineering Center (72) Inventor Shigeki Iijima Isogo-ku, Yokohama-shi, Kanagawa 1 Shin-Nakaharacho Ishi Kawashima-Harima Heavy Industries, Ltd. Yokohama Engineering Center

Claims (4)

[Claims] 1. An electric furnace wherein a raw material powder charged into a furnace main body is subjected to a heat treatment in a heating area, and the produced powder is taken out from the furnace main body, wherein a predetermined gas is blown into the furnace main body. A gas supply means, and a discharge nozzle for discharging the predetermined gas from the furnace main body, wherein the discharge nozzle is configured to discharge a first nozzle from the furnace main body before the predetermined gas reaches the heating region; Is discharged from the furnace body after passing through the heating area.
An electric furnace comprising a nozzle. 2. The apparatus according to claim 1, wherein a plurality of the second nozzles are arranged along a flow direction of the predetermined gas.
An electric furnace as described. 3. A circulation path for the predetermined gas is formed such that the predetermined gas discharged from the first nozzle is blown into the furnace main body by the gas supply unit. An electric furnace as described. 4. The electric furnace according to claim 3, wherein a heat exchanger is interposed in the circulation path to exchange heat between the temperature management fluid supplied to the furnace main body and the predetermined gas.