JP4113970B2 - DC electric resistance type reduction melting furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct current electric resistance type reduction melting furnace. More specifically, the present invention melts incineration ash of domestic waste, incineration ash of industrial waste, dried sewage sludge powder, etc. The present invention relates to a direct current electric resistance type reduction melting furnace for melting and reducing oxides.
[0002]
[Prior art]
Conventionally, in a DC electric resistance reduction melting furnace, one graphite electrode is inserted into the melt from the top of the furnace, and a current is passed between the graphite electrode and the bottom electrode (for example, a patent) Reference 1). Furthermore, the furnace wall refractory may use a conductive carbonaceous refractory (for example, carbon stamp or carbon brick).
In addition, a DC electric resistance reduction melting furnace has a method in which two graphite electrodes are inserted into a material to be melted from the upper part of the furnace, and a current is passed between the currents of the two electrodes. Is not energized. Therefore, in such a case, a non-conductive magnesia chrome brick or the like is usually used as the furnace wall refractory.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 09-196573 [0004]
[Problems to be solved by the invention]
The challenges are as follows.
(1) Since the refractory constituting the furnace wall is consumed, it is necessary to periodically repair the refractory. This has the problem that it takes time to maintain the DC electric resistance reduction melting furnace.
[0005]
(2) When the life of the refractory constituting the furnace wall is to be extended, it is necessary to cool the furnace wall with water. This has a problem that the structure becomes complicated.
(3) It is necessary to reduce heat radiation loss due to heat conduction from the furnace wall. However, when the road wall is water-cooled at the same time as in (2), the heat radiation loss due to heat conduction from the furnace wall becomes large.
[0006]
Note that Patent Document 1 discloses that a self-baking electrode used as a Soederberg electrode is used as an electrode disposed in the upper part of the furnace. However, even with such a configuration, the problems of items {circle around (1)} to {circle around (3)} cannot be solved.
Therefore, an object of the present invention is to provide a direct current electric resistance type reductive melting furnace that can solve these problems.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, the DC electric resistance type reduction melting furnace according to the invention of claim 1 applies a voltage between the electrodes to pass a current through the melted material accommodated in the furnace, In a direct current electric resistance type reductive melting furnace that heats and melts the material to be melted by Joule heat, one electrode is configured to form a wall in the furnace and the supplied first coal tar is melted. The first coal tar supply section communicates with a wall section in the furnace .
[0008]
The direct current resistance type reductive melting furnace according to claim 2 is the direct current resistance type reductive melting furnace according to claim 1, wherein the other electrode is an upper electrode installed on the furnace. The second coal tar that is supplied is formed by sintering with the heat generated by the melt , and the second coal tar supply portion is formed integrally with the furnace electrode. .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
This embodiment is a direct current electric resistance reduction melting furnace such as a reduction electric melting furnace or a ferroalloy furnace (alloy iron furnace) for reducing and melting heavy oxides contained in incinerated ash and separating them into slag and heavy metals.
[0010]
FIG. 1 shows the configuration of this DC electric resistance reduction melting furnace. As shown in FIG. 1, the resistance reduction melting furnace is roughly composed of a furnace body 10, a furnace lid 20, a furnace electrode 30, and a DC power supply 40.
The furnace body 10 is a structure composed of a main body portion 12 in which a material to be melted 200 is accommodated and a supply portion 13 to which coal tar 100 is supplied, and the outside is covered with a steel sheet-made iron skin. The main body 12 has a bottomed cylindrical shape, for example. As for the main-body part 12, the furnace wall and the furnace bottom are comprised by the refractory materials 14 and 15. FIG. Hereinafter, the refractory constituting the furnace wall is referred to as the furnace wall refractory 14, and the refractory constituting the furnace bottom is referred to as the furnace bottom refractory 15.
[0011]
The furnace bottom refractory 15 is, for example, magnesia / chrome brick.
The furnace wall refractory 14 is formed of coal tar 100 supplied from the supply unit 13, and is a so-called self-fired graphite refractory formed using coal tar 100 as a raw material using heat of fusion in the furnace. It is. This furnace wall refractory 14 forms a furnace wall electrode as a conductive graphite in a DC electric resistance reduction melting furnace. The furnace wall refractory 14 is provided with a connector 41 connected to a DC power source 40. The reason why the furnace wall refractory 14 is a self-fired graphite refractory will be described in detail later.
[0012]
The supply unit 13 is provided on the outer periphery of the upper end of the main body 12 and has a communication structure with a portion of the main body 12 where the furnace wall refractory 14 is formed. That is, the supply unit 13 has a shape that can supply the coal tar 100 supplied from the outside to the main body unit 12. For example, the supply unit 13 has a cylindrical shape.
For example, the supply amount of the coal tar 100 is controlled in the supply unit 13 by a control unit (not shown).
[0013]
The furnace lid 20 is a lid that closes the upper opening of the main body 12. Above the furnace lid 20, a coal tar 100 supply unit 21 is provided. The supply unit 21 has a cylindrical shape, for example. For example, the supply unit 21 is formed integrally with the furnace lid 20 or the furnace body 10. One furnace electrode 30 is disposed in the center portion of the furnace lid 20 so as to extend from the supply section 21 and penetrate into the furnace.
[0014]
Although not shown, the furnace lid 20 is formed with a melt supply part (supply hole) for supplying the melt into the furnace body 10. In addition, for example, the supply unit 21 is configured such that the supply amount of coal tar 100 is controlled by a control unit (not shown).
The on-furnace electrode 30 has a cylindrical shape as a whole, and has a sufficient length so that the tip end portion is inserted into the melt 200 in the furnace body 10. The on-furnace electrode 30 is formed of coal tar 100 supplied from the supply unit 21, and is a so-called self-fired graphite electrode formed using coal tar 100 as a raw material using heat of fusion in the furnace. is there. The reason why the furnace electrode 30 is a self-fired graphite electrode will be described in detail later.
[0015]
An electrode holder 42 connected to a DC power source 40 is attached to the furnace electrode 30.
The direct current electric resistance reduction melting furnace is configured as described above. Next, the operation of this DC electric resistance reduction melting furnace will be described.
After the melt 200 is supplied to the furnace body 10, when a voltage is applied between the connector 41 and the electrode holder 42 by the DC power supply 40, the gap between the furnace electrode 30 and the furnace wall refractory 14 of the furnace body 10 is applied. When a voltage is applied to the to-be-melted body 200, a direct current is applied to the melt 200 in the furnace body 10. Thus, the melt 200 is heated by Joule heat, and when the melt 200 contains heavy metal oxide, the slag and the metal are separated by specific gravity by reductive melting, and the molten metal 300 is formed at the furnace bottom. Accumulate. Accordingly, since the heavy metal is conductive, the current is diverted from the furnace electrode 30 not only to the furnace wall refractory 14 but also to the furnace bottom. Then, by continuously operating the DC electric resistance reduction melting furnace, a current flows radially in the furnace, that is, the entire furnace, so that the melt 200 is soaked and melted.
[0016]
At this time, the furnace electrode 30 is formed as a graphitized electrode (graphite electrode) by the coal tar 100 supplied from the supply unit 21 due to its heat conduction, and the furnace wall refractory 14 is also supplied from the supply unit 13. Due to the supplied coal tar 100, a graphitized electrode (graphite electrode) is formed. As described above, the furnace electrode 30 and the furnace wall refractory 14 are formed as so-called self-fired graphite electrodes by sintering using the heat of fusion of the material 200 to be melted.
[0017]
At this time, the supply amount of coal tar 100 is controlled in each of the supply units 13 and 21 in accordance with the degree of electrode formation or the degree of electrode wear. That is, the coal tar 100 is continuously supplied and the amount of the continuous supply is controlled.
Next, the effect will be described.
[0018]
Usually, a DC electric resistance furnace requires positive and negative electrodes in the furnace. This electrode generally comprises an electrode installed at the top of the furnace and an electrode at the bottom of the furnace. These electrodes are usually oxidized and consumed.
On the other hand, the present invention includes the furnace electrode 30 and the furnace wall refractory 14 formed by sintering the supplied coal tar 100 with the heat generated by the melt 200 as described above. Yes. Thereby, although the furnace electrode 30 and the furnace wall refractory 14 are oxidized and consumed, the furnace electrode 30 and the furnace wall refractory 14 also correspond to the consumption by continuously replenishing the coal tar 100. It is made to form continuously. This eliminates the need for regular addition work and periodic repair work for electrode consumption, which has been conventionally performed.
[0019]
Further, since the furnace wall refractory 14 also has a function as a furnace wall, it is not necessary to provide an electrode paired with the furnace electrode separately from the furnace wall.
In addition, since it is not necessary to consider the life of the furnace wall, it is not necessary to perform water cooling that has been performed to extend the life of the furnace wall.
Further, since periodic addition work for electrode wear and periodic repair work for furnace wall wear are not required, it is not necessary to stop operation for that work.
[0020]
Moreover, as mentioned above, the furnace electrode 30 and the furnace wall refractory 14 are formed by sintering with the heat which the to-be-melted material 200 generate | occur | produces. Therefore, the electrode can be generated by effectively utilizing the heat loss that radiates heat outside the furnace.
FIG. 2 shows the thermal efficiency of this DC electric resistance reduction melting furnace. As shown in FIG. 2, it can be seen that there is heat loss from the furnace lid and the furnace wall. In the present invention, an electrode can be manufactured by effectively utilizing the heat that would otherwise be lost.
[0021]
Moreover, the carbon of the furnace electrode 30 and the furnace wall refractory 14 contributes to the reduction reaction of the heavy metal oxide contained in the melt 200 as a reducing agent.
Further, since the electrode area can be increased, the current can be distributed throughout the furnace, the temperature distribution can be made uniform, and the material to be melted can be uniformly melted. .
[0022]
The embodiment of the present invention has been described above. However, the present invention is not limited to being realized as the above-described embodiment.
That is, in the above-described embodiment, both the furnace electrode 30 and the furnace wall refractory 14 are described as electrodes formed by sintering the supplied coal tar 100 with the heat generated by the melt 200. did. However, the present invention is not limited to this, and at least only the furnace wall refractory 14 may be formed as an electrode formed by sintering the supplied coal tar 100 with the heat generated by the melt 200. .
[0023]
【The invention's effect】
According to the present invention, an electrode formed by sintering the supplied coal tar with the heat generated by the melted material, for example, effectively utilizing the heat generated by the melted material. This can eliminate the need for electrode repair work.
[Brief description of the drawings]
FIG. 1 shows a configuration of a DC electric resistance reduction melting furnace according to an embodiment of the present invention.
FIG. 2 is a diagram used for explaining the effect.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Furnace 12 Main body part 13 Supply part 14 Furnace wall refractory 15 Furnace bottom refractory 20 Furnace lid 21 Supply part 30 Furnace electrode 40 DC power supply 41 Connector 42 Electrode holder 100 Coal tar 200 Melted material 300 Molten metal

Claims (2)

In a DC electric resistance type reductive melting furnace in which a voltage is applied between the electrodes to pass a current through the melted material accommodated in the furnace and the melted material is heated and melted by Joule heat.
One electrode is configured to form a wall in the furnace, and the first coal tar supplied is sintered by heat generated by the melted material ,
The direct current resistance type reductive melting furnace, wherein the first coal tar supply section communicates with a wall section in the furnace. The other electrode is a furnace electrode installed on the furnace, and the second coal tar that is supplied is formed by sintering with the heat generated by the melted material ,
The DC electric resistance type reduction melting furnace according to claim 1, wherein the second coal tar supply part is formed integrally with the furnace electrode .

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