JPH1038475A - DC ash melting furnace - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: In a movable electrode made of carbon, a portion in contact with incineration ash becomes high temperature and is considerably consumed by oxidation, so that the electrode may be damaged. SOLUTION: An electrode cover 13 in which a movable electrode insertion portion 14 which enables vertical sliding of a movable electrode 4 is formed at an upper portion, and a substantially bowl-shaped main body portion 15 which is opened at a lower portion is formed at a lower portion, is provided. It is supported in the furnace via stays 16 and 17. Further, an inert gas supply pipe 18 is connected to the outside of the electrode cover main body 13, and an inert gas is supplied into the electrode cover 13 from an end thereof. Thereby, since the movable electrode 4 in the electrode cover 13 is covered with the inert gas, consumption and loss due to oxidation are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC ash melting furnace for applying a DC current to incinerated ash remaining after incineration of municipal waste and sewage sludge, and heating and melting the incinerated ash by Joule heat to perform an integrated treatment. About.

[0002]

2. Description of the Related Art Conventionally, in order to facilitate the handling of incinerated ash remaining after incineration of municipal garbage and sewage sludge, a direct current is applied to the incinerated ash itself to generate Joule heat and heat and melt the powder. The incineration ash has been integrated. The direct current type ash melting furnace used in this process has a main body formed in a crucible shape with refractory bricks or carbon, and a furnace bottom electrode is buried at the bottom, and supported by an elevating mechanism at the top furnace top. A movable electrode made of carbon is provided. The incineration ash to be treated is put into the furnace, the movable electrode is lowered from above, and the lower end is kept inserted in the incineration ash. When a current is passed between the two electrodes in this state, Joule heat is generated due to the resistance of the incinerated ash, and the incinerated ash is heated. When the melting temperature is reached, the powdered incinerated ash is melted and integrated. The incinerated ash that has been melted and integrated facilitates handling of subsequent transportation, storage, and disposal.

[0003]

However, since the conventional DC ash melting furnace uses a carbon electrode as the movable electrode, the exposed portion is exposed to high-temperature air compared with the portion covered in the incineration ash. Due to exposure to the inside, consumption by oxidation is remarkable. In particular, since the surface of the incinerated ash (the liquid surface when it is melted) is at a high temperature, it is significantly consumed by oxidation, and its diameter gradually becomes smaller and narrower. FIG. 3 shows the progress of the oxidation. As the oxidation progresses, the electrode is eventually broken and the lower part falls. As a countermeasure for this, it is conceivable to fill an inert gas such as nitrogen in the furnace so that oxygen is not supplied to the exposed electrode portion. However, in order to fill the furnace with an inert gas, it is necessary to partition the inside of the furnace from the outside and keep it in a sealed state.However, since the furnace itself is in a high temperature and dusty atmosphere, it is difficult to completely seal it structurally. Impossible
If the inert gas is sealed in that state, the consumption of the inert gas increases to replenish the leakage,
It was not practical because of the scattering of incineration ash and the release of heat. Therefore, there has been a demand for the development of a DC ash melting furnace which can reduce the consumption of the movable electrode by a simple method.

[0004]

Therefore, in order to solve the above-mentioned problems, the present invention has an electrode disposed inside a furnace bottom and a movable electrode made of carbon supported on a furnace top so as to be vertically movable. By injecting incineration ash into the furnace body and applying a direct current between both electrodes with the lower end of the movable electrode inserted in the incineration ash, Joule heat is generated in the incineration ash itself to heat and melt the incineration ash In the direct current type ash melting furnace, a movable electrode insertion portion that allows the inserted movable electrode to slide in the vertical direction is formed on the upper portion, and the lower portion has a larger diameter than the insertion portion and has a lower portion opened. By supporting the electrode cover having the substantially bowl-shaped main body in the furnace via a stay, the lower end of the electrode cover is held below the surface of the incinerated ash heated in the furnace.

Further, an inert gas supply pipe communicating with the inside of the main body is connected to the outside of the main body of the electrode cover, and the inert gas is supplied into the electrode cover from an end thereof. As a result, the lower end of the electrode cover is held below the surface of the incinerated ash, the inside and outside of the cover are shut off, and only the upper movable electrode insertion part communicates with the outside, and the inert gas sent from the inert gas device is When the gas is filled in the electrode cover, some inert gas is released from the movable electrode insertion portion to the outside. As a result, the portion of the movable electrode that is in contact with the incineration ash surface is always covered with the inert gas, and is not oxidized even at high temperatures, thereby preventing the electrode itself from being consumed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a DC ash melting furnace according to the present invention. In the figure, reference numeral 1 denotes a furnace main body formed in a crucible shape, which is made of a refractory material such as a refractory brick or carbon. On the furnace body 1, a furnace lid 2 also made of a refractory material is formed. A furnace bottom electrode 3 is embedded in the inside bottom of the furnace body 1. The incineration ash A to be treated is put inside the furnace body 1, and the movable electrode 4 is inserted through the central opening of the upper furnace lid 2. The movable electrode 4 is supported by a lifting device 10 including an electrode lifting mast 5, a wire 6, a pulley 7, a wire drum 8, a drum driving motor 9, and the like so as to be movable up and down. The lifting device may be driven by hydraulic pressure.

A thyristor rectifier 11 is connected to the movable electrode 4 and the furnace bottom electrode 3 as a DC power supply.
Here, when the thyristor rectifier 11 is operated and a direct current flows between the electrodes 3 and 4 in a state where the lower end of the movable electrode 4 is inserted into the incineration ash A, Joule heat using the incineration ash A as a resistance load is generated. Occur. The incineration ash A itself in a powder state is heated and melted and integrated by the Joule heat. The configuration and operation up to this point are the same as the conventional one. Next, the configuration of the present invention will be described.

In this embodiment, the electrode cover shown in FIG. 2 is used to cover the periphery of the movable electrode 4 with an inert gas. In FIG. 2, reference numeral 13 denotes an electrode cover body made of ceramic, and a movable electrode insertion portion 14 is formed at the upper portion by a cylinder having an inner diameter slightly larger than the outer diameter of the movable electrode 4. At the lower end of the insertion portion 14, a cover portion 15 made of a cylinder having a larger diameter is formed continuously. The disc-shaped portion where the insertion portion 14 and the cover portion 15 are connected has two opposite
Stays 16 and 17 are protruded upward at the respective locations. The stays 16 and 17 hold the electrode cover main body 13 at a predetermined position in the furnace by supporting the tips of the stays on the furnace lid 2.

Similarly, a pipe 18 is connected to the disc-shaped portion. The other end of the pipe 18 is connected to an inert gas supply device (not shown) to supply an inert gas into the electrode cover body 13. Both the insertion portion 14 and the cover portion 15 have open ends, and the movable electrode 4 is inserted into the inside thereof while being installed in the furnace. The electrode cover body 13 of this embodiment
Has a convex shape due to a combination of large and small cylinders, but the cover portion 15 can be formed in a bowl shape.

Next, as shown in FIG. 1, the electrode cover body 13 thus configured is supported on the furnace lid 2 by stays 16 and 17 after the axis of the electrode cover body 13 is aligned with the movable electrode 4 in the furnace body 1. Let it. At the same time, the pipe 18 is pulled out of the furnace through the furnace lid 2 and connected to an inert gas supply device (not shown). A specific configuration of the inert gas supply device includes a cylinder for storing an inert gas such as nitrogen, a regulator, a solenoid valve, a cock, and the like. In this state, the movable electrode 4 is inserted into the insertion portion 14 and is driven up and down by the lifting device 10, so that the incineration ash A is held at an optimal position.

Next, the thyristor rectifier 11 is operated to supply a DC current between the electrodes 3 and 4, and the inert gas supply device is operated to pass the inert gas into the electrode cover body 13 through the pipe 18. Supply. The electrode cover body 13
When the inert gas is supplied, the initially filled air is removed from the insertion section 14, and the entire inside is filled with the inert gas. Here, the supply pressure of the inert gas is set to be higher than the atmospheric pressure.
The inert gas leaks upward through 4. This leakage can be reduced by making the gap between the insertion portion 14 and the movable electrode 4 inside the insertion portion 14 as small as possible.

As described above, at least the portion of the movable electrode 4 which is in contact with the surface of the incineration ash A is always covered with the inert gas, so that it is not contacted with oxygen in the air. As a result, even if the in-furnace ash A is melted due to the heating in the furnace and the surface thereof becomes high temperature, the movable electrode 4 in contact with the portion will not be consumed by oxidation, and the electrode is prevented from being damaged. In this embodiment, the electrode cover body is made of ceramic, but may be made of another material such as a heat-resistant metal.

[0013]

As described above, according to the present invention, the periphery of the movable electrode and the surface of the incineration ash are covered with the electrode cover and an inert gas is supplied into the inside thereof. Is always in an inert gas atmosphere, so that the electrodes are not oxidized even at high temperatures. As a result, the vicinity of the surface of the incinerated ash of the electrode is not oxidized and consumed, thereby preventing the electrode from being damaged, thereby preventing the occurrence of an electrode loss accident.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of a DC ash melting furnace according to the present invention.

FIG. 2 is an external perspective view of an electrode cover main body in FIG.

FIG. 3 is an explanatory view showing a state of oxidative consumption in a conventional movable electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 2 Furnace lid 3 Furnace bottom electrode 4 Movable electrode 5 Electrode lifting mast 6 Wire 7 Pulley 8 Wire drum 9 Drum drive motor 10 Lifting device 11 Thyristor rectifier 13 Electrode cover main body 14 Movable electrode insertion part 15 Cover part 16, 17 Stay 18 piping A incineration ash

Claims (1)

[Claims] An electrode is disposed inside the furnace bottom,
Injecting incineration ash into the furnace body in which a movable electrode made of carbon is vertically movable on the top of the furnace, and applying a direct current between both electrodes while the lower end of the movable electrode is inserted into the incineration ash, In a DC ash melting furnace that generates Joule heat in the incineration ash itself to heat and melt the incineration ash, a movable electrode insertion part that allows the inserted movable electrode to slide up and down is formed at the top, An electrode cover formed at the lower part with a substantially bowl-shaped main body having a diameter larger than that of the insertion portion and opening downward, a stay supporting the electrode cover in a furnace and holding the electrode cover at a predetermined level, An inert gas supply pipe connected to the outside of the main body and communicating with the inside of the main body; and an inert gas supply device connected to an end of the inert gas supply pipe and supplying the inert gas into the electrode cover. Specially DC type ash melting furnace to be.