JPH085247A - Plasma type melting furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an economical plasma melting furnace for melting incinerator ash or the like, which is easy to restart and has a simple electrode structure. A plasma-type melting furnace for heating and melting a melted material A composed of waste ash or incineration ash, or a composition of which is adjusted, and a melting furnace main body 21 for containing the melted material A, A pair of electrodes 24, which are provided in the melting furnace main body 21 so as to be positioned above the material A to be melted accommodated in the melting furnace main body 21 and eject the plasma gas 26,
25, one electrode 24 serves as an anode and the other electrode 25 serves as a cathode, and a plasma arc P is formed by a direct current from the DC power supply device 30 to heat and melt the material A to be melted. Also, these electrodes 24, 25
The position of is movable during the initial heating of the melted material A and during the steady heating.

Description

Detailed Description of the Invention

[0001]

The present invention relates to the incineration ash of waste,
The present invention relates to a plasma-type melting furnace for melting and processing for volume reduction, pollution-free, recycling and the like.

[0002]

2. Description of the Related Art As described above, furnaces for melting and treating incineration ash, etc. for volume reduction, pollution-free, recycling, etc., include swirling melting furnaces, coke beds (vertical shaft furnaces), surface melting furnaces. There are a method of burning fuel as a heating source for a furnace and a method of using electricity as a heating source for an arc furnace, a plasma furnace, a microwave furnace, and the like. However, in the method of burning fuel, the melting temperature of the material to be melted such as incinerated ash is 1200 ° C to 1
Although it is 600 ° C, the combustion temperature is usually about 2000 ° C, and the temperature difference from the melting temperature of the material to be melted is small,
For this reason, the thermal efficiency becomes poor and it is not economical. Further, even in such a fuel combustion system, if the combustion is carried out with an oxygen-enriched gas, the combustion temperature rises, but the economical efficiency is further impaired. On the other hand, the method of using electricity has the advantages of high temperature and a small amount of exhaust gas, so that it has high thermal efficiency and is economical.

Of these types of furnaces that use electricity,
In a plasma melting furnace, a DC (direct current type) plasma melting furnace in which an anode and a cathode are installed above and below the molten steel in the furnace, mainly for heating a continuous casting machine for molten steel, and the molten steel in the furnace An AC (alternating current type) plasma melting furnace in which two or more electrodes are installed above is conventionally known. Among these, as the one using the former plasma type melting furnace for melting the incineration ash, for example, one shown in FIG. 5 is known. This is Japanese Patent Laid-Open No. 25355/1993.
No. 7, the cathode 2 and the anode 3 are installed so as to be located above and below the material A to be melted such as incineration ash stored in the melting furnace body 1, and the cathode 2 and By ejecting the plasma gas 4, the melted material A is heated and melted by the plasma arc. In the figure, reference numerals 5, 6 and 7 respectively represent a melted material supply facility, a flow rate adjusting device, and an exhaust gas treatment facility. The melted material A is discharged as slag.

[0004]

However, when the incineration ash or the like is melted as the material A to be melted in this way, the incineration ash itself is not conductive when it is solid, and only when it is in a molten state is a saturated aqueous solution of salt. Since a certain degree of conductivity is generated, if the melted material A of the incineration ash is cooled and solidified, the conductivity is lost. Therefore, even if the melting furnace is restarted from the state where the melted material A is cooled and solidified and the melted material A is heated and melted again, the plasma arc is not formed as it is, and therefore pretreatment is required. It is unavoidable that the operation becomes complicated and becomes complicated. Further, the melted material A such as incineration ash exhibits a severe corrosive property when melted, so that the anode 3 installed at the bottom of the melting furnace main body 1 is corroded as the heating and melting progress, impairing the economical efficiency. The problem also arises.

On the other hand, an electrode is installed above the furnace A
When the C plasma melting furnace is applied to melting incineration ash or the like, such problems as pretreatment at the time of restart and erosion of electrodes can be avoided. However, in such a melting furnace, since the power source is an alternating current, as shown in FIG. 6, the internal electrode 9 forming the cathode 2 and the internal portion forming the anode 3 are formed at the tip of the nozzle 8 of the electrode for ejecting the plasma gas 4. Electrode 9
Are required respectively, which inevitably complicates the structure of the electrode and also results in a loss of economic efficiency. In addition, reference numerals 10 and 11 in the drawing are flow paths of cooling water supplied to the starter electrode and the nozzle 8, respectively.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an economical plasma type for melting incineration ash or the like which is easy to restart and has a simple electrode portion structure. To provide a melting furnace.

[0007]

In order to solve the above problems and to achieve the above object, the present invention provides a melting furnace main body for containing a material to be melted, and the above melting target to be melted contained in the melting furnace main body. At least one pair of electrodes provided in the melting furnace main body so as to be positioned above the object and ejecting plasma gas, at least one of these electrodes serving as an anode, and the remaining at least one serving as a cathode. It is characterized in that the material to be melted is heated and melted by a plasma arc method.

[0008]

According to the plasma type melting furnace having such a structure,
Since the electrode that ejects the plasma gas is installed above the material to be melted inside the melting furnace body, even if the material to be melted such as incinerated ash is in a solid state at the time of restarting etc., no pretreatment is required. A plasma arc can be formed between the electrodes, and erosion due to the melted melted material can be avoided. Further, one of the electrodes is an anode and the other is a cathode, that is, since the material to be melted is heated and melted by a DC power source, each electrode may be either an anode or a cathode. Therefore, the structure of the electrode can be simplified.

It is desirable that the positions of these electrodes can be moved between the initial stage of heating the object to be melted, such as at restart, and the steady state heating after the object has been melted to some extent. By adopting such a configuration, when the melted material such as incineration ash is in a solid state and has no conductivity, at the time of restart, etc., both electrodes are brought close to each other and a hollow plasma arc is formed between the anode and the cathode. And the object to be melted in the state of having no conductivity due to the radiant heat can be heated and melted. Further, after the material to be melted is melted to some extent in this way and conductivity is generated, the electrodes are separated from each other, and a plasma arc is formed through the material to be melted, which becomes conductive, thereby radiating heat and Joule heat. Thus, the material to be melted can be efficiently heated and melted.

[0010]

1 to 4 show one embodiment of the present invention. In these figures, reference numeral 21 indicates
It is a melting furnace main body of the plasma type melting furnace, and its inner wall is covered with a refractory material 22. This melting furnace body 2
A pair of electrodes 24 and 25 are provided on the upper lid portion 23 of the No. 1 so as to project downward in the furnace. As shown in FIG. 2, a nozzle 27 for ejecting the plasma gas 26 is provided at the tips of these electrodes 24, 25, and an internal electrode 28 is provided at the center of the nozzle 27.
Further, the nozzle 27 is provided with a flow path 29 for supplying cooling water.

A DC power supply device 30 is connected to each of the internal electrodes 28 of the electrodes 24 and 25, and one electrode 24 is used as a positive electrode and the other electrode 25 is a negative electrode. It is used as an electrode. A plasma gas supply device and a cooling water supply device (not shown) are connected to both electrodes 24 and 25, and the plasma gas and the cooling water are supplied to the nozzle 27 and the flow passage 29 at appropriate supply amounts and supply pressures, respectively. It is possible to supply.

Further, a driving device (not shown) is attached to the electrodes 24 and 25, and both electrodes 24 and 25 are driven by this driving device at the initial stage of heating the material A to be melted stored in the melting furnace main body 21. The position is movable during heating in the steady state. That is, at the beginning of heating, the tips of both electrodes 24, 25 are arranged close to each other as shown in FIG. 3, while at the time of steady heating, as shown in FIG. It is movable so as to be spaced apart.

A melted material supply hole 31 is provided in the center of the upper lid portion 23 of the melting furnace body 21, and a melted material supply facility 32 is connected to the supply hole 31.
Further, the upper lid portion 23 is provided with a gas discharge hole 33, and the gas discharge hole 33 is connected to an exhaust gas treatment facility 34. Further, a melt discharge hole 35 is opened in the side wall of the melting furnace body 21, and the melted material A
Is discharged from the discharge hole 35 to the outside of the melting furnace main body 21. The electrodes 24 and 25 are arranged by the driving device so that their tips are located above the lower edge of the melt discharge hole 35 during the initial heating and the steady heating, that is, the melting furnace main body 21. It is arranged to be located above the material A to be melted stored in.

In the plasma-type melting furnace having such a structure, the melted material A made of waste ash or incineration ash, or a composition of these ash or incineration ash is adjusted.
Is supplied into the melting furnace main body 21 from the melted material supply equipment 32 through the supply hole 31, ejects the plasma gas 26 from the electrodes 24 and 25, and uses the DC power supply device 30 to make the electrode 24 an anode and the electrode 25. By forming a plasma arc P by applying a direct current as a cathode,
It is heated and melted by the radiant heat and Joule heat, and is discharged from the discharge hole 35. Here, in a state where the melting furnace is stopped and the melted material A in the furnace is solidified and solidified, such as when restarted, the melted material A has no conductivity as described above. When the melting furnace is restarted from such a state, the plasma gas 26 is jetted with the tips of the electrodes 24 and 25 brought close to each other by the drive unit as shown in FIG. To the electrodes 24, 2 directly on the surface of the melted material A.
A plasma arc P is formed by the hollow discharge between 5,
The material A to be melted is heated exclusively by the radiant heat.

Then, after the material A to be melted is heated and melted to a certain extent by this, and the material A to be melted becomes conductive,
As shown in FIG. 4, both electrodes 24 and 2 are driven by the driving device.
5 are separated from each other, and a plasma arc P is formed through the plasma gas 26 jetted from the electrodes 24 and 25 and the melted material A, and when radiant heat of the plasma arc P and the melted material A are passed by a direct current. The object A to be melted is heated and melted by the Joule heat of. Further, the melted material A thus melted is discharged from the melt discharge hole 35 and processed, and the exhaust gas generated during heating and melting is discharged from the exhaust gas discharge hole 33 and processed by the exhaust gas processing equipment 34. .

As described above, according to the plasma type melting furnace having the above-described structure, the plasma arc P is formed between the pair of electrodes 24 and 25 located above the material A to be melted contained in the melting furnace body 21. Since the material A to be melted is heated and melted by a hollow discharge even when the material A to be melted is in a solid state and does not have conductivity such as when restarting. By the radiant heat of the plasma arc P
The material A to be melted can be heated and melted without performing pretreatment. Further, during steady heating after the melted material A is melted to some extent and conductivity is thereby generated, the plasma arc P is formed through the melted material A, so that the radiant heat of the plasma arc P is generated. The material A to be melted can be efficiently heated and melted by the Joule heat.
Furthermore, since both electrodes 24 and 25 are installed so as to be located above the material A to be melted in the melting furnace body 21,
It is possible to prevent the electrodes 24 and 25 from being eroded by the melted material A that is heated and melted and has a severe erosion property.
It is possible to extend the service life of 4, 25.

Furthermore, in the plasma type melting furnace having the above structure, the electrode 2 is supplied by the direct current from the DC power supply device 30.
Since the plasma arc P is formed between 4 and 25 to heat and melt the material A to be melted, one of the pair of electrodes 24 and 25 may be used as an anode and the other of the pair of electrodes may be used as a cathode. Since only one internal electrode 28, which serves as an anode or a cathode, needs to be provided at 25, the structure of the electrodes 24 and 25 can be simplified. Therefore, according to the plasma-type melting furnace having the above-described configuration, restarting is facilitated without requiring pretreatment, efficient heating and melting can be promoted during steady heating, and the electrode has a simple structure and It is possible to provide a plasma-type melting furnace which can have a long life and, as a result, is extremely economical.

In addition to these, in the plasma type melting furnace of this embodiment, the position of the electrodes 24 and 25 can be moved by the driving device at the time of restarting and at the time of steady heating. While the electrodes 24 and 25 are close to each other, both electrodes 24 and 25 are separated from each other during steady heating. Therefore, at the time of restarting when the melted material A has no conductivity, a hollow discharge can be promptly generated between the electrodes 24 and 25, and the melting heat of the melted material A can be promoted by the radiant heat of the plasma arc P. On the other hand, during steady heating when the melted material A has conductivity, the plasma arc P is surely formed through the melted material A to stabilize efficient heating by radiant heat and Joule heat. It becomes possible to do it. Therefore, by moving the positions of the electrodes 24 and 25 according to the state of the melted material A to form the plasma arc P in this manner, according to the present embodiment, the heat melting of the melted material A is effectively performed. It becomes possible to do so, and the economic efficiency thereof can be further improved.

In this embodiment, the pair of electrodes 24 and 25 are provided on the melting furnace main body 21 and one of them serves as an anode and the other serves as a cathode. However, depending on the scale of the melting furnace and the composition and amount of the material A to be melted, etc. Provides a plurality of pairs of electrodes, one of which serves as an anode, and the other of which serves as a cathode, and D is provided between them.
A DC current may be supplied by the C power supply device to form a plasma arc.

[0020]

As described above, according to the present invention, even when the object to be melted has no conductivity, the object to be melted can be heated and melted by radiant heat without performing pretreatment, while the object to be melted By forming a plasma arc through the material to be melted during steady-state heating where conductivity is generated, efficient heating and melting can be promoted by radiant heat and Joule heat. Moreover, the corrosion of the electrode due to the melted material can be prevented, the life of the electrode can be extended, and the structure of the electrode itself can be simplified. It is possible to provide a high plasma melting furnace.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma melting furnace showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing tips of electrodes 24 and 25 of the embodiment shown in FIG.

FIG. 3 is an electrode 2 upon restart of the embodiment shown in FIG.
It is sectional drawing which shows the position of 4,25.

4 is an electrode 2 during steady heating of the embodiment shown in FIG.
It is sectional drawing which shows the position of 4,25.

FIG. 5 is a cross-sectional view showing a conventional DC plasma melting furnace.

FIG. 6 is a sectional view showing a tip portion of an electrode of an AC plasma melting furnace.

[Explanation of symbols]

 21 Melting Furnace Main Body 24 Electrode (Anode) 25 Electrode (Cathode) 26 Plasma Gas 27 Nozzle 28 Internal Electrode 30 DC Power Supply Device 32 Molten Material Supply Equipment 34 Exhaust Gas Treatment Equipment 35 Melt Discharge Hole A Molten Material P Plasma Arc

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Keiichiro Miyano, 2-17-15 Tsukushima Machine, Chuo-ku, Tokyo Tsukishima Machinery Co., Ltd. (72) Inventor Yoshikazu Nagayoshi 2-17-15 Tsukushima, Chuo-ku, Tokyo Tsukishima Machine Incorporated (72) Inventor Charles Peter Henley England UK 79 7 AJ Oxfordshire Far Lyndon Letchled Road 5B Tetronics Research and Development Company Limited (72) Inventor John Kenneth Williams UK UK 7 8 NJ Oxon Farringdon Stanford in the Vail 4 ST Denise Close

Claims (2)

[Claims] 1. A plasma melting furnace for heating and melting a melted material composed of waste ash or incinerated ash, or a composition of the ash or incinerated ash, the melting furnace containing the melted material. A main body and at least a pair of electrodes for ejecting plasma gas, which are provided in the melting furnace main body so as to be located above the material to be melted accommodated in the melting furnace main body, and at least these electrodes are provided. One is an anode, and the other at least one is a cathode, and the plasma type melting furnace is characterized in that the above-mentioned melted material is heated and melted by a plasma arc method. 2. The plasma-type melting furnace according to claim 1, wherein the position of the electrode is movable between the initial stage of heating of the object to be melted and the steady state heating.