JP2001241639A - Automatic control device for electric resistance type melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically perform horizontal and vertical movement of electrodes and discharge of molten slag according to the temperature and level of the molten slag, save electric power consumption and prevent breakage of a transformer, a furnace wall or the like. SOLUTION: A device comprises a plurality of electrodes 3, 4 which are disposed inside of an electric resistance type melting furnace 1, a horizontal movement device 7 for horizontally moving these electrodes, and an ammeter 14 for measuring the value of electric current that runs through the electrodes. The horizontal movement device is driven to control the distance between the electrodes based on the electric current value measured by the ammeter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an electric resistance melting furnace for melting incineration ash generated when incinerating general waste and industrial waste.

[0002]

2. Description of the Related Art Incinerated ash obtained by incinerating general waste or industrial waste at 900 ° C. or less contains substances and metals which are harmful to the environment and humans, and these harmful substances such as PCB and dioxin are contained. Means for eliminating pollution, lead, cadmium and the like cannot be solved by incinerators using ordinary fuels. If this incinerated ash is directly disposed of in landfills, it is natural that water and soil pollution will occur. In addition, recently, the above-mentioned metals are eluted due to acid rain reaching pH 3 and seriously affect drinking water. Give it.

Hitherto, in order to solve this problem, various methods have been proposed to melt incinerated ash to detoxify harmful substances. Since the furnace used for this purpose needs to minimize the oxygen present in the furnace, a furnace using oil and gas that burns a large amount of air cannot be used, and therefore, an electric furnace is used. Electric furnaces are like high-frequency furnaces, but it is difficult to create a large volume of space, and electric arc furnaces generate an arc between the molten metal and the graphite electrode, Although a melt is generated by heat, it is not desirable because furnace damage and electrode wear are severe due to high temperature, and enormous power is required. The most desirable electric furnace for carrying out the method is that the furnace is substantially sealed and has low air inflow,
It is essential to use an electric resistance melting furnace in which the inorganic melt itself generates heat using electric resistance to maintain the furnace temperature.

A basic patent for this electric resistance melting furnace is disclosed in Japanese Patent No. 1334791 (Japanese Patent Publication No. 60-56963).
This will be described with reference to FIG. On the ceiling 102 of the melting furnace 101, three graphite electrodes 103 for three-phase alternating current are provided so as to be able to move up and down through the ceiling 2. The ceiling 102 is provided with a chute 105 for inserting the incineration ash 104, an air port 106 for supplying combustion air, and an exhaust port 107, and the air port 106 is provided with a control valve 108 for adjusting the amount of air. I have. Further, a tap hole 110 for a metal melt 109 is provided at a lower portion of the melting furnace 101.

A current is applied to the electrode 3 whose tip is buried in the metal melt 109, and is higher than the melting temperature of the metal melt 109 by Joule heat using the metal melt 109 as a resistor.
Heat to about 0-1500 ° C. The incineration ash 104 is supplied from the chute 105 to the entire liquid surface of the metal melt 109. The supplied incineration ash 104 is sequentially melted from a portion in contact with the liquid surface of the metal melt 109, and a small amount of exhaust gas generated at the time of melting is discharged from the exhaust port 107. Incineration ash 1
The metal contained in the incineration ash accumulates at the bottom as a molten metal layer by melting of the incineration ash 04, on which the inorganic melt of the incineration ash separates to form a glass layer. The molten metal and the inorganic melt (hereinafter, referred to as molten slag) are sequentially taken out from tap hole 110.

[0006]

By the way, in the electric resistance type melting furnace, in the initial stage of the melting process, iron chips and copper chips are densely filled around the electrode 103 at the bottom of the melting furnace 101, The graphite electrode 103 is energized to melt the metal 109
Need to be formed. However, in the above-mentioned conventional electric resistance type melting furnace, the distance between the electrodes 103 is fixed and the melting temperature of the metal melt 109 cannot be controlled, so that the power consumption increases and the transformer and the road wall are damaged. In addition, since the level of the molten slag is unknown, it is not possible to accurately determine the charging timing of the incineration ash or the like, and there is a problem that the processing time becomes long.

The present invention solves the above-mentioned conventional problems, and automatically processes horizontal movement, vertical movement and discharge of molten slag according to the temperature and level of molten slag to save power consumption. An object of the present invention is to provide an automatic control device for an electric resistance type melting furnace capable of preventing damage to a transformer and a road wall.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of electrodes 3 and 4 disposed inside an electric resistance melting furnace 1 and a plurality of electrodes 3 are arranged horizontally. It comprises a horizontal moving device 7 for moving and a current measuring device 14 for measuring a current value flowing through the electrodes, and controls the distance between the electrodes by driving the horizontal moving device based on the current value measured by the current measuring device. The invention according to claim 2 is characterized in that, in claim 1, a temperature detection device 11 is provided inside the melting furnace, and based on a temperature of the molten slag 2 detected by the temperature detection device, 4. The method according to claim 3, wherein the distance between the electrodes is controlled by driving a horizontal moving device.
The invention described in claim 1 or 2, wherein an up-down moving device 6 for moving the electrode up and down is provided, and the electrode is moved up and down based on the current value or the temperature.
According to a fourth aspect of the present invention, in any one of the first to third aspects, an on-off valve 10 is provided at the bottom of the melting furnace, and a level detecting device 12 is disposed inside the melting furnace. On the basis of the value detected by the device, the on-off valve is driven to discharge the molten slag to the outside. Note that the numbers added to the above configuration are compared with the drawings to facilitate understanding of the present invention, and the configuration of the present invention is not limited by this.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of an automatic control device for an electric resistance melting furnace according to the present invention.

The melting furnace 1 is filled with a molten slag 2,
A center electrode 3 and two opposing electrodes 4 are arranged to face the center electrode 3 so as to be inserted into the molten slag 2.
Each of the electrodes 3 and 4 is mounted on a lifting stage 5, and the lifting stage 5 is provided so as to be vertically movable by a plurality of vertical moving devices 6. The opposing electrodes 4 are provided so as to be horizontally movable on the elevating stage 5 by the horizontal moving devices 7. A tapping pipe 9 is provided at the bottom of the melting furnace 1, and an on-off valve 10 for opening and closing the tapping pipe 9 is provided.

A temperature detecting device 11 for detecting the temperature of the molten slag 2 in a non-contact manner and a level detecting device 12 for detecting the level of the molten slag in a non-contact manner are provided above the melting furnace 1. On the primary side of the transformer 13, three-phase power supplies U, B, W
Are connected, the secondary terminal B of the transformer 13 is connected to the center electrode 3, and the secondary terminals A and C are connected to the current measuring devices 14 and 14, respectively.
Are connected to the opposing electrodes 4 and 4 via. The vertical moving device 6, the horizontal moving device 7, the on-off valve 10, the temperature detecting device 11, the level detecting device 12, and the current measuring device 14 are connected to the automatic control device 15.

The control of the electric resistance type melting furnace having the above configuration will be described. The electrodes 3, 4 whose tips are buried in the molten slag 2 are energized and 1400 higher than the melting temperature of the molten slag 2 by Joule heat using the molten slag 2 as a resistor.
Heat to about 1500 ° C. Incinerated ash is molten slag 2
And the supplied incinerated ash is sequentially melted from the portion in contact with the liquid surface of the molten slag 2, and a small amount of exhaust gas generated during melting is discharged from the exhaust port 107.
As the incineration ash 104 is melted, the metal component contained in the incineration ash accumulates at the bottom as a molten metal layer, on which the inorganic melt of the incineration ash separates to form a glass layer. The molten metal and the inorganic melt are sequentially taken out of the tapping pipe 9.

The current flowing through the counter electrode 4 is measured by a current measuring device 14, and the automatic control device 15
When the current flowing through the electrode exceeds the specified value, the horizontal moving device 7 is driven to move the opposing electrode 4 horizontally, and the distance between the electrodes 3 and 4, that is, the electric resistance value is increased and returned to a current within the specified value. The transformer 13 is prevented from being damaged. If the horizontal current does not return to the specified current value, the automatic controller 15 moves the elevating stage 5 upward to increase the electric resistance between the electrodes 3 and 4 so that the current within the specified value is obtained. Return to

When the melting temperature of the molten slag 2 exceeds the specified value as measured by the temperature detecting device 11, the automatic control device 15 drives the horizontal moving device 7 to move the counter electrode 4 horizontally, The electric resistance between the electrodes 3 and 4 is increased to reduce the current between the electrodes 3 and 4, thereby lowering the melting temperature of the molten slag 2 and preventing damage to the inner wall of the melting furnace.

Further, the level of the molten slag is measured by the level detecting device 12, and if the measured level and the temperature of the molten slag 2 are the specified values, the automatic control device 15
Operates the on-off valve 10 to discharge the molten slag 2 to the outside.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made. For example, in the above embodiment, two counter electrodes 4 are provided for the center electrode 3, but
Only one counter electrode 4 may be provided, or three or more counter electrodes 4 may be provided for the center electrode 3.

[0017]

As is apparent from the above description, according to the present invention, the horizontal and vertical movement of the electrode and the discharge of the molten slag are automatically processed according to the temperature and level of the molten slag, thereby saving power consumption. And the damage of the transformer and the road wall can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an automatic control device for an electric resistance melting furnace according to the present invention.

FIG. 2 is a sectional view of a conventional electric resistance melting furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Melting furnace 2 ... Molten slag 3, 4 ... Electrode 6 ... Vertical moving device 7 ... Horizontal moving device 10 ... Open / close valve 11 ... Temperature detecting device 12 ... Level detecting device 14 ... Current measuring device

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Claims (4)

[Claims] 1. An electric resistance measuring furnace comprising: a plurality of electrodes disposed inside an electric resistance melting furnace; a horizontal moving device for horizontally moving these electrodes; and a current measuring device for measuring a current value flowing through the electrodes. An automatic control device for an electric resistance type melting furnace, wherein a distance between electrodes is controlled by driving a horizontal moving device based on a current value measured by the device. 2. A method for controlling a distance between electrodes by disposing a temperature detecting device inside the melting furnace and driving a horizontal moving device based on a temperature of the molten slag detected by the temperature detecting device. The automatic control device for an electric resistance type melting furnace according to claim 1, wherein 3. The electric resistance type melting furnace according to claim 1, further comprising a vertical movement device for vertically moving the electrode, wherein the electrode is vertically moved based on the current value or the temperature. Automatic control device. 4. An on-off valve is provided at the bottom of the melting furnace, and a level detecting device is disposed inside the melting furnace. The on-off valve is driven based on values detected by the level detecting device and the temperature detecting device. The automatic control device for an electric resistance type melting furnace according to any one of claims 1 to 3, wherein the molten slag is discharged to the outside.