JPH05261358A - Method and apparatus for melting incineration ash - Google Patents

Abstract

PURPOSE:To increase melting capacity and to melt incineration ash within a short time with high efficiency by melting incineration ash by both of the resistance heat generated by the current flowing through unmelted incineration ash made conductive from an electrode and the heat of the arc generated from the electrode. CONSTITUTION:When incineration ash is melted in a furnace 1 by the arc generated from an electrode 6, molten slag 15 is foamed to be infiltrated in unmelted incineration ash 16 to make the incineration ash conductive. A current flows into the conductive unmelted incineration ash 16 to generate resistance heat and the unmelted incineration ash 16 is also heated and melted by said heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting residues of incinerated municipal waste and the like, and incinerator ash such as dust in an incinerator for reducing the volume, and a melting apparatus therefor.

[0002]

2. Description of the Related Art Unmelted incinerated ash is deposited on a molten slag in a furnace, and an electric power is applied to an electrode arranged above the molten slag to generate an arc from the electrode, and the heat of the arc causes The unmelted incinerated ash is heated and melted (see, for example, JP-A-62-49988).

This type of incineration ash melting method has the advantages that it has a large melting capacity because it is heated by a high temperature arc, and that it can be efficiently melted in a short time.

[0004]

In this type of incinerator ash melting method and melting apparatus, if the melting capacity is desired to be further increased, a method of increasing the input power for generating the arc is conceivable. However, in such a case, there are problems that the consumption of the electrodes is increased and the noise is increased with the generation of a large arc.

The present invention has been made to solve the above-mentioned problems (technical problems) of the prior art. It is possible to melt unmelted incineration ash by both heating by high temperature arc and heating by resistance heat. In addition, it has a large melting capacity and can perform efficient melting in a short time. Moreover, even if the melting capacity is large, the consumption of electrodes and the generation of noise are suppressed to a low level. It is an object to provide a melting method and a melting device.

[0006]

In order to achieve the above object, the method for melting incinerated ash according to the present invention is such that the lower end portion of the electrode arranged above the molten slag is buried on the molten slag in the furnace. In a method for melting incinerated ash, in which the unmelted incinerated ash deposited on the electrode is melted by electric power applied to the electrode, the molten slag under the unmelted incinerated ash is foamed in order to convert the unmelted incinerated ash into a conductor. Infiltrate it into the unmelted incineration ash above and form an electric current from the electrode into the conductive unmelted incinerated ash, and the unmelted incinerated ash flows in the unmelted incinerated ash. It is melted by both the resistance heat generated by the electric current and the heat of the arc generated by the electrode.

[0007]

The unmelted incineration ash is heated and melted by the arc generated from the electrode. Foamed molten slag is infiltrated into the unmelted incinerated ash, and the unmelted incinerated ash is made into a conductor.
An electric current also flows from the electrode through the unmelted incineration ash made into a conductor. The unmelted incinerated ash is heated by the heat of the arc and the resistance heat generated in the unmelted incinerated ash when the current flows.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the incinerator ash melting apparatus shown in FIG. 1, 1 indicates a furnace. Reference numeral 2 denotes a main body of the furnace 1, which is made of a refractory material as is well known. Reference numeral 3 denotes a charging space and an outlet port formed inside the furnace body, respectively. Reference numeral 5 denotes the ceiling of the furnace 1. Next, reference numeral 6 denotes an arc-generating electrode provided so as to penetrate the ceiling 5, and in the case of an AC arc furnace, a plurality (for example, three) are provided as well known, although not shown. In the case of a DC arc furnace, a bottom electrode is additionally provided. Reference numeral 7 indicates an incineration ash charging port, and 8 indicates an exhaust gas outlet. Next, 9 is a through hole provided at a high position on the side wall of the furnace body 2 for inserting a gas body inlet pipe, into which a foaming gas body inlet pipe 10 is detachably inserted. Reference numeral 11 denotes an inlet for the gas body, which is constituted by the tip of the inlet pipe 10. The through hole 9 may be provided in the ceiling 5. 1 shows the operating state of the melting apparatus, 14 is a base metal, 15 is molten slag spread on it, 16 is unmelted incinerated ash deposited on the molten slag 15, for example, It has a granular or powdery shape of about 5 to 10 mm. In the above-mentioned unmelted incinerated ash 16, the unmelted incinerated ash in the range in which the foamy molten slag permeates and is filled (the range covered by the foamed molten slag. The range indicated by the hatched lines in the figure) Reference numerals 18 denote arcs generated between the lower end 6a of the electrode 6 and the base metal 14, respectively.

Next, the operation of the melting device will be described. In the initial stage of operation, by applying electric power to the electrode 6, it is deposited on the base metal 14 by an arc emitted from the electrode 6, for example, an arc generated between the lower end 6a of the electrode 6 and the base metal 14. Unmelted ash
16 is heated. The unmelted incinerated ash 16 is melted by the heating and becomes molten slag 15 and spreads on the base metal 14. An example of the composition of the molten slag 15 is that Al ₂ O ₃ is 1
2-25%, SiO ₂ 30-75%, CaO 7-1
5%, FeO is 1 to 25%. The temperature of the arc is 3000 ° C and the temperature of the molten slag 15 is about 1400 ° C.

After the molten slag 15 is formed as described above, the inlet pipe 10 is inserted through the through hole 9 so that the inlet 11 is located in the molten slag 15, and the bubble is passed through the inlet pipe 10. Introducing a gas body for atomization, for example, air, and introducing it 11
Is blown into the molten slag 15 from. By this blowing, oxygen contained in the gas body reacts with unburned components (mainly carbon) generated from incineration ash, and CO gas or CO
₂ Gas is generated. A part of the molten slag 15 is foamed by the gas and the remaining oxygen or nitrogen in the foaming gas body. The foamed molten slag thus generated permeates into the unmelted incinerated ash 16 deposited on the foamed molten slag, and the unmelted incinerated ash 17 in the permeated range is made into a conductor. In this state, the arc generated from the electrode 6, for example, the arc generated between the lower end 6a and the base metal 14
The unmelted incineration ash is heated and melted by 18 and at the same time,
From the lower portion 6b of the electrode 6, that is, the portion 6b with which the unmelted incinerated ash 17 made into a conductor by permeation of the foamy molten slag comes in contact, the current flows to the unmelted incinerated ash 17 made into a conductor (between the electrodes or between the electrodes). 6 and molten slag 15), depending on the current,
The unmelted incinerated ash 17 made into a conductor and in contact with the periphery of the lower portion 6b of the electrode 6 generates heat due to resistance heat, and the unmelted incinerated ash due to the heat is also melted in parallel.

During the above-mentioned operation, the molten slag 15 formed on the base metal 14 by melting the unmelted incinerated ash sequentially flows out from the outlet 4 as is well known. In addition, new unmelted incineration ash 16 is charged from the charging port 7. On the other hand, the exhaust gas generated by the melting is discharged from the exhaust gas outlet 8.

Next, the combustion of unburned components during the above operation will be described. Approximately 3% of the unburned ash remains in the unmelted incineration ash 16. This unburned component evaporates during heating and melting in the furnace 1 (mainly carbon). However, in the melting device, in the process in which the air sent through the inlet pipe 10 passes through the individual unmelted incinerated ash 16, the unburned components and the air in the air generated from the individual unmelted incinerated ash It is efficiently mixed with oxygen (each of the unmelted incineration ash serves as a mixing device), and burns to form CO gas or CO ₂ gas.
The CO gas in the gas generated as described above is used as a heat source for other equipment after being discharged from the exhaust gas outlet 8.

Next, in the operation of the above-mentioned melting apparatus, carbonaceous powder may be fed together with the gas body for foaming through the feeding pipe 10. When such carbon is fed, the foamed molten slag can be formed more actively.
It is also effective in keeping the arc 18 from the electrode 6 stable. In addition, when carbon powder is to be fed, the feeding pipe
It is advisable to raise 10 a little and position the inlet 11 in the unmelted incineration ash.

During the above operation, carbon C in the unmelted incinerated ash 16, iron oxide FeO in the molten slag 15, and the inlet pipe
A reaction of FeO + C → Fe + CO occurs due to C or the like in the foaming gas body fed into the furnace through 10.
In this case, if the carbon C generated from the unmelted incineration ash 16 is insufficient, the carbon of the carbon-based refractory that constitutes the furnace is utilized in the above reaction, and the carbon-based refractory is damaged. However, when carbon is fed through the feed pipe 10 as described above, carbon is replenished for the above reaction, and damage to the refractory can be prevented. The iron produced by the reduction of the iron oxide is mixed in the base metal 14.

[0015]

As described above, in the present invention, when the unmelted incinerated ash is melted, the unmelted incinerated ash is heated by the arc 18 generated from the electrode 6. Of course, there is an effect that can be achieved, for example, a large melting ability can be exhibited due to a high-temperature arc, and an effect of efficiently melting in a short time,

In the case of the above-mentioned melting, in the present invention, since the unmelted incinerated ash 17 is made into a conductor by the foamed molten slag, in addition to the heating by the arc 18, the inside of the unmelted incinerated ash 17 made into a conductor is The unmelted incinerated ash can be heated by the resistance heat generated in the unmelted incinerated ash due to the flow of the electric current, which has the effect of further increasing the melting capacity.

Moreover, even if the melting capacity can be increased as described above, the lower portion 6b of the electrode 6 is covered with the foamed molten slag during the heating of the unmelted incinerated ash. It has the effect of suppressing the oxidation of the electrode lower part 6b by the atmospheric gas inside and reducing the consumption thereof, and since the arc 18 is also wrapped with the foamed molten slag, the sound emission caused by the arc generation is suppressed. It also has the effect of suppressing noise and reducing noise.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an incineration ash melting device.

[Explanation of symbols]

 1 Furnace 6 Electrode 10 Foaming gas inlet tube 15 Molten slag 16 Unmelted incinerated ash 17 Unmelted incinerated ash penetrated by foamed molten slag 18 Arc

Claims (2)

[Claims] 1. Melting of incinerated ash, in which unmelted incinerated ash deposited on the molten slag in the furnace so that a lower end portion of an electrode arranged above the molten slag is buried by electric power applied to the electrode In the method, in order to make the unmelted incinerated ash into a conductor, the molten slag under the unmelted incinerated ash is foamed to penetrate it into the upper unmelted incinerated ash, and the conductive material is applied from the electrode. An electric current is passed through the unmelted incinerated ash that has been solidified, and the unmelted incinerated ash is melted by both the resistance heat generated by the current flowing in the unmelted incinerated ash and the heat of the arc generated from the electrode. A method for melting incinerated ash, which is characterized by: 2. A furnace for containing the molten slag and the unmelted incinerated ash to be deposited on the molten slag, and an electrode for producing an arc for heating the unmelted incinerated ash is provided inside the furnace. The melting apparatus for incinerated ash, wherein the melting apparatus for incinerating ash is provided with an inlet pipe for feeding a gas body for foaming the molten slag into the molten slag in the furnace.