JPH10288321A - Electrical resistance melting furnace of refuse incinerated ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the corrosion of electrodes by molten salt and prevent the electric current from the electrodes from flowing to the molten salt and enhance melting efficiency to molten slags. SOLUTION: This melting furnace arranges an electrode 3 to rise and fall freely inside a cylinder-shaped body 4 supported on an upper furnace cover 2 in a refuse incinerated ash melting electrical resistance furnace provided with the graphite electrode 3 by using an electrode lift device while the cylinder- shaped body 4 comprises an insulating refractory in the outer layer and an expandable refractory in the inner layer. In this case, the graphite electrode 3 is arranged to connect an electrode having a specified length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incineration ash electric resistance melting furnace which melts incineration ash generated when incinerating waste such as municipal solid waste, sewage sludge, industrial waste and the like to form slag.

[0002]

2. Description of the Related Art Since incinerated ash from municipal waste contains a large amount of harmful substances such as heavy metals, it is difficult to directly dispose of or incinerate municipal incinerated ash by leaching harmful substances. There is a safety problem from the above.

[0003] For this reason, Japanese Patent Application Laid-Open No. 7-77318 proposes that slag is formed by melting incinerated ash using an AC electric resistance melting furnace.

FIG. 5 is an overall view of a conventional AC electric resistance melting furnace, in which three graphite electrodes 3 are provided on an upper furnace lid 2 of a furnace body 1.
The tip of the graphite electrode 3 is immersed in the molten slag of the furnace, AC current is applied to the molten slag by applying an AC voltage to the graphite electrode 3, and the ash itself is resisted by Joule heat based on the electric resistance of the molten slag in a molten state. The body generates electric resistance heat, and the heat keeps the molten state of the slag and heats and melts the ash by the heat transfer from the molten slag. The incineration ash supplied into the furnace is melted by electric resistance heating, and each layer of molten metal, molten slag, and molten salt is generated from the lower layer.
The molten metal is discharged from the molten metal tap hole 1a,
Similarly, the molten slag is discharged from the molten slag outlet 1b, and the molten salt is discharged from the molten salt outlet 1c.

[0005]

Since fly ash generated from a refuse incinerator contains a large amount of salts such as KCl and NaCl, molten salt is generated together with molten slag when melting the incinerated ash. Is done. During operation, the electrode is
a ^{+ +} 2C1 ^- or 2K ⁺ + 2C1 ^- that there is a problem of corrosion by oxidation.

Further, since the molten salt has a high conductivity, the current from the electrode flows intensively into the molten salt layer in the low resistance portion,
There is also a problem that Joule heat generated in the molten slag is reduced and the molten slag is not sufficiently heated.

Therefore, the present invention provides an electric power generation system for refuse incineration ash which prevents corrosion of an electrode by molten salt and prevents current from the electrode from flowing into the molten salt, thereby improving the melting efficiency of molten slag. A resistance melting furnace is provided.

[0008]

According to the present invention, there is provided an electric resistance melting furnace for refuse incineration ash provided with a graphite electrode, wherein the electric resistance melting furnace for refuse incineration ash is provided inside a tubular body supported by an upper furnace lid. The graphite electrode is arranged so as to be able to move up and down by an electrode elevating device, and the cylindrical body has an outer layer made of an insulating refractory and an inner layer made of a foaming refractory.

As the graphite electrode, an electrode formed by connecting electrodes of a predetermined length is used.

[0010]

FIG. 1 is an overall view showing an embodiment of an electric resistance melting furnace according to the present invention, FIG. 2 is a sectional view of a tubular body and a graphite electrode shown in FIG. 1, and FIG. Cross-sectional view, FIG. 2- (b)
FIG. 3 is a longitudinal sectional view, and FIG. 3 is a perspective view of the tubular body and the graphite electrode shown in FIG.

The electric resistance melting furnace shown in FIG. 1 is a three-phase AC electric resistance melting furnace, in which three graphite electrodes 3 are provided on an upper furnace lid 2 of a furnace body 1, and each graphite electrode 3 is supported by the upper furnace lid 2. The inside of the formed cylindrical body 4 is provided so as to be movable up and down by an electrode lifting device 5. Furnace body 1 includes molten metal formed in the furnace,
In order to discharge molten slag and molten salt, a molten metal tapping port 1a, a molten slag tapping port 1b and a molten salt tapping port 1c for tapping molten salt are provided. The upper furnace lid 2 is provided with an ash supply port 2a for supplying incinerated ash and an exhaust gas outlet 2b for discharging gas generated in the electric furnace.

As shown in FIGS. 2 and 3, the cylindrical body 4 is
The outer layer is composed of an insulating refractory 4a and the inner layer is composed of a foaming refractory 4b, and the tubular body 4 is provided downward so as to be immersed in a molten slag layer in an electric furnace. As the insulating refractory of the outer layer, a refractory having an insulating property against molten salt,
For example, silica brick or magnesia brick is used. Further, the foamable refractory of the inner layer acts as a cushioning material between the expanding electrode and the insulating refractory of the outer layer,
For example, it is made of a heat-insulating plastic refractory or the like.

The end of the graphite electrode 3 projects from the lower end of the cylindrical body 4. The graphite electrode 3 in the tubular body 4 is connected by a male screw 3a and a female screw 3b formed at an end of the graphite electrode 3 having a predetermined length.

In the above configuration, an alternating current is applied to the molten slag by applying an alternating voltage to the graphite electrode, and the ash itself is converted into a resistor by the Joule heat based on the electric resistance of the molten slag in a molten state, thereby obtaining an electric resistance heat. Is generated, and the ash is heated and melted by maintaining the molten state of the slag by the heat and by transferring heat from the molten slag. Due to the melting of the ash, a molten metal layer, a molten slag layer, and a molten salt layer are generated from a lower layer in the furnace.
The molten metal is discharged from the molten metal outlet 1a, the molten slag is discharged from the molten slag outlet 1b, and the molten salt is discharged from the molten salt outlet 1c.

Since the graphite electrode 3 is protected from the molten salt by the cylindrical body 4 and does not come into contact with the molten salt, it is not eroded by the molten salt. Further, since the graphite electrode 3 is electrically insulated from the molten salt by the tubular body 4 disposed to a position below the generated molten salt, the current from the graphite electrode 3 melts the low-resistance portion. The molten slag is no longer concentrated and flows, and the molten slag is sufficiently heated by the current flowing through the molten slag layer.

When the tip of the graphite electrode 3 protruding from the cylindrical body 4 is worn out during operation, the graphite electrode 3 having a predetermined length is screwed and connected to the upper end of the graphite electrode 3, and the graphite lifting and lowering device 5 is used for the graphite electrode 3. The electrode 3 is lowered to project from the cylindrical body 4.

FIG. 4 is an overall view showing another embodiment of the electric resistance melting furnace of the present invention. The electric resistance melting furnace shown in FIG. One graphite electrode 3 is provided, and a furnace bottom electrode 6 is provided on the furnace bottom of the furnace main body 1 so as to face the graphite electrode 3. The graphite electrode 3 covers the inside of the cylindrical body 4 supported by the upper furnace lid 2. It is provided to be able to move up and down by an electrode lifting device 5.

In the single-phase AC electric resistance melting furnace of this embodiment, the structures of the furnace main body 1, the upper furnace lid 2, and the cylindrical body 4 are the same as those of the above-described embodiment, and the description thereof will be omitted.

In the above configuration, an alternating current is applied to the molten slag by applying an alternating voltage between the graphite electrode and the furnace bottom electrode, and the molten state of the slag is maintained by Joule heat based on the electric resistance of the molten slag in the molten state. Then, the ash is heated and melted by the heat transfer from the molten slag. The melting of the ash creates a molten metal layer, a molten slag layer, and a molten salt layer in the furnace,
The molten metal is discharged from the molten metal tap hole 1a,
Similarly, the molten slag is discharged from the molten slag outlet 1b, and the molten salt is discharged from the molten salt outlet 1c.

Since the graphite electrode 3 is protected from the molten salt by the tubular body 4 and does not come into contact with the molten salt, it is not eroded by the molten salt. In addition, since the graphite electrode 3 is electrically insulated from the molten salt by the cylindrical body 4, the current from the graphite electrode 3 does not concentrate on the molten salt layer, and
The molten slag is sufficiently heated by the electric current flowing through the molten slag layer.

[0021]

In order to protect the graphite electrode by the cylindrical body,
Since the corrosion of the electrodes due to the molten salt or the short circuit between the electrodes can be prevented, the frequency of consumption of the electrodes can be improved and a stable operation can be performed.

Further, since the electrodes are connected and fed out with electrodes of a predetermined length, the electrode tips protruding from the lower end of the cylindrical body are worn by operation, but by sending out the shortage, a sufficient voltage is supplied into the furnace. It becomes possible to apply.

[Brief description of the drawings]

FIG. 1 is an overall view showing an embodiment of an electric resistance melting furnace of the present invention.

FIG. 2 is a sectional view of the tubular body and the graphite electrode shown in FIG.
FIG. 2A is a transverse sectional view, and FIG. 2B is a longitudinal sectional view.

FIG. 3 is a perspective view of a tubular body and a graphite electrode shown in FIG. 1;

FIG. 4 is an overall view showing another embodiment of the electric resistance melting furnace of the present invention.

FIG. 5 is an overall view of a conventional AC electric resistance melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 1a Molten metal tap 1b Molten slag tap 1c Molten salt tap 2 Upper furnace lid 2a Ash supply port 2b Exhaust gas outlet 3 Graphite electrode 3a Male screw 3b Female screw 4 Cylindrical body 4a Insulating refractory 4b Foaming refractory 5 Electrode lifting device 6 Furnace bottom electrode

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshifumi Hasegawa 46-59, Nakahara, Tobata-ku, Kitakyushu City Inside Nippon Steel Plant Design Co., Ltd.

Claims (2)

[Claims] In an electric resistance melting furnace for refuse incineration ash provided with graphite electrodes, a graphite electrode is disposed inside a tubular body supported by an upper furnace lid so as to be able to move up and down by an electrode lifting device. An electric resistance melting furnace for refuse incineration ash, wherein the outer layer is made of an insulating refractory and the inner layer is made of a foaming refractory. 2. The electric resistance melting furnace for incinerated ash according to claim 1, wherein the graphite electrode is an electrode formed by connecting electrodes of a predetermined length.