JPH08121739A - Electric melting furnace - Google Patents

Abstract

PURPOSE: To prolong the life of a refractory of the overflow unit of a tapping hole and permit the stabilized tapping of a molten metal from the tapping hole. CONSTITUTION: In an overflow tapping type electric melting furnace, in which matters to be molten 8, such as the ash of incineration, the dust of soot and the like which are generated from an incinerating furnace, are molten by an electrode 2 while molten matters 8a are tapped by overflowing from a tapping hole 4, an air flow passage 11 for cooling the refractory of an overflow unit is formed in the overflow unit of the tapping hole 4. The terminal unit of the cooling air flow passage 11 is opened in the tapping hole 4 and cooling air 15, which cooled the refractory, is supplied into the tapping hole 4 to burn combustible gas 9, generated by the melting of the matters to be molten 8, in the tapping hole 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overflow tap type electric melting furnace used for melting a melted material such as incinerated ash or dust generated when incinerating general waste or industrial waste. Therefore, the refractory in the overflow section of the tap hole is cooled with cooling air, and the flammable gas generated in the melting furnace is burned by this cooling air, and the combustion heat is used to melt the overflow from the tap hole. It relates to an electric melting furnace adapted to heat an object.

[0002]

2. Description of the Related Art Conventionally, a large amount of general waste and industrial waste are incinerated in a refuse incinerator to render them harmless and reduce their volume, and incinerator ash and dust are landfilled. However, since the incinerated ash and soot and dust contain harmful substances such as heavy metals and dioxins, there is a risk that environmental pollution will occur after landfill treatment, and securing landfill sites is becoming difficult year by year. , Has caused various problems in practice.

Therefore, in order to solve the above problems,
Recently, by further melting and solidifying combustion ash and dust,
Measures are being taken to make it harmless and further reduce the volume.
For this melting and solidification, combustion-type melting furnaces that use fuels such as oil and gas, and electric melting furnaces such as arc furnaces, plasma furnaces, and electric resistance furnaces are mainly used, but in cities that require melting and solidification. In many cases of waste incinerators, electric power is generated by using the combustion heat of the waste, and therefore surplus power can be used, and therefore, there are many cases in which an electric melting furnace, for example, an overflow melting type electric melting furnace is used.

FIGS. 5 and 6 show an example of a conventional overflow melting type electric melting furnace of this kind. In the melting furnace main body 20, arc heat from an electrode 21 (graphite electrode) produces incineration ash or the like. The melted material 22 is melted, and the melted material 22a accumulated on the bottom of the furnace is sequentially discharged from the overflow portion of the discharge opening 23 to the outside. In addition, the combustible gas 24 generated by melting the melted material 22 is
Through the exhaust gas to the combustion chamber outside the furnace where it is re-burned by using auxiliary fuel. This is because, when the combustible gas 24 is burned in the melting furnace, the vicinity of the graphite electrode 21 becomes an oxidizing atmosphere, and the oxidizing consumption becomes severe.

In the overflow tap type electric melting furnace, when the overflow amount (processing amount) of the melt 22a is decreased, the melt 22a is cooled in the tap hole 23 so that the fluidity is lowered and It will be difficult and in some cases it will solidify. Therefore, in the electric melting furnace shown in FIG. 5, the auxiliary electrode 26 is provided near the tap hole 23 on the furnace wall side.
In the electric melting furnace shown in FIG. 6, the auxiliary burner 27 for city gas is used.
Are provided respectively to heat the melted material 22a in the tap hole 23.

[0006]

However, the melt 22
In the conventional electric melting furnace in which the auxiliary electrode 26 and the auxiliary burner 27 are provided in the vicinity of the tap hole 23 in order to facilitate the tapping of a, the heating by the auxiliary electrode 26 and the auxiliary burner 27 and the melt 22a itself are Due to the high temperature, there is a problem that the corrosiveness of the melt 22a is great and the life of the refractory at the overflow portion of the tap hole 23 becomes extremely short.

The present invention was created in order to solve the above-mentioned problems, and its purpose is to extend the life of the refractory material by cooling the refractory material at the overflow portion of the tap hole with cooling air. , Overflow tap electric melting that burns combustible gas generated in the melting furnace by heated refractory cooling air and uses the combustion heat to stably discharge the melt from the tap To provide a furnace.

[0008]

In order to achieve the above object, the electric melting furnace of the present invention melts a material to be melted such as incinerated ash and dust from a refuse incinerator with an electrode, and melts this molten material. In an overflow hot-melting type electric melting furnace adapted to overflow from a tap hole, a cooling air flow path for cooling refractory in the overflow section is formed in the overflow section of the tap hole, and the cooling air is formed. The end of the flow path is opened to the tap, and cooling air that has cooled the refractory is supplied into the tap so that flammable gas generated by melting the material to be melted is burned in the tap. Is.

[0009]

[Operation] In the electric melting furnace, the melted material such as combustion ash and soot dust from the refuse incinerator supplied into the furnace is melted by the arc heat of the electrode, the plasma heat or the Joule heat of the melted material itself. Then, it becomes a fluid melt, overflows from the overflow portion of the tap hole, is cooled by water cooling or air cooling, and is then discharged.

At the overflow portion of the tap hole, cooling air is constantly supplied to the cooling air passage, and the refractory inside the overflow portion is cooled by the cooling air. As a result, the life of the refractory in the overflow portion is significantly extended. Further, the cooling air that has cooled the refractory in the overflow portion is jetted into the tap hole from the end opening of the cooling air flow path.

On the other hand, the flammable gas generated when the material to be melted is melted in the melting furnace is sucked from the inside of the furnace to the tap hole side,
By being mixed with the heated refractory cooling air in the tap hole, it is almost completely combusted. This high temperature combustion exhaust gas is discharged to the outside from the exhaust gas discharge port while heating the melt flowing in the overflow portion. As a result, the melt in the tap hole maintains its fluidity and taps smoothly and satisfactorily.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an overflow hot-melting type electric melting furnace according to an embodiment of the present invention, in which 1 is a furnace body, 2 is a graphite electrode, 3 is a melted material supply port, 4 is a tapping port, 5 is a hot water discharge port, and 6 Is a combustion exhaust gas discharge port, 7 is a cooling water tank, 8 is a melted material such as incineration ash or soot dust, 8a is a melted material, 9 is a combustible gas, 10 is a combustion exhaust gas, 11 is a cooling air flow path, and 12 is cooling. The air supply pipe 13 is a cooling fan.

The furnace body 1 has a side wall 1a and a ceiling wall 1b formed of refractory such as castable refractory and refractory bricks.
And the furnace bottom 1c is formed into a substantially box shape, and the side wall 1a
The melted material supply port 3 for feeding the melted material 8 into the furnace
And a tap hole 4 for tapping the molten material 8a in the furnace. Further, on the downstream side of the tap hole 4, there are a hot water discharge port 5 for guiding the melt 8a discharged from the hot water port 4 to the cooling water tank 7, and a combustion exhaust gas discharge port 6 for discharging the combustion exhaust gas 10 to the outside, respectively. It is formed in a communicating state.

In the electric melting furnace of the present invention,
In the overflow portion 1d of the tap hole 4, a cooling air passage 11 for cooling the refractory material in the overflow portion 1d is formed. That is, in this embodiment, the cooling air passage 11
As shown in FIG. 2, is provided in the lower portion, side surface portion and weir portion of the runner 14 formed in the overflow portion 1d from the inside of the furnace to the hot water discharge port 5, and the refractory material in substantially the entire area of the overflow portion 1d It has a branched structure so that it can be cooled. Further, each terminal portion 11a of the cooling air flow path 11 is open to the hot water outlet 4, and the cooling air 15 can be supplied into the hot water outlet 4. Furthermore, the cooling air flow path 1
A cooling air supply pipe 12 and a cooling fan 13 are connected to the starting end of the cooling device 1 so that the cooling air 15 can be supplied to the cooling air passage 11.

As the refractory material of the overflow portion 1d forming the cooling air flow passage 11, a refractory material that can be easily processed in the cooling air flow passage 11 and is suitable for the chemical composition and characteristics of the melt 8a. in use. In this embodiment, magnesia dolomite, magnesia calcia, etc. are used as the refractory material.

In the electric melting furnace configured as described above, the material to be melted 8 such as incinerated ash and dust from the refuse incinerator supplied to the furnace is melted by the arc heat of the graphite electrode 2. Becomes a fluid melt 8a, overflows from the overflow portion 1d of the tap hole 4 to the hot water discharge port 5 side, is cooled in the cooling water tank 7, and is then discharged.

At this time, the overflow section 1 of the tap hole 4
At d, since the cooling air 15 is constantly supplied from the cooling fan 13 and the cooling air supply pipe 12 to the cooling air flow path 11, the cooling air 15 causes the inside of the refractory material in the overflow portion 1d to be cooled. Is cooled. As a result, the life of the refractory material in the overflow portion 1d is significantly extended. or,
Cooling air 1 for cooling the refractory in the overflow section 1d
5 is jetted into the tap hole 4 from the opening of the terminal end 11a of the cooling air flow path 11.

On the other hand, the combustible gas 9 generated when the material 8 to be melted is melted in the melting furnace is sucked from the furnace to the tap 4 side, and the refractory material heated in the tap 4 is cooled. By being supplied and mixed with the working air 15, it is almost completely combusted. This high temperature combustion exhaust gas 10 flows into the overflow portion 1
Combustion exhaust gas discharge port 6 while heating the melt 8a flowing through d
Is discharged from the outside. As a result, the melted material 8a in the tap hole 4 retains its fluidity, and tapping is smoothly and favorably performed.

In this electric melting furnace, the combustion air of the combustible gas 9 (cooling air 15) is supplied into the tap hole 4,
Since the combustion exhaust gas 10 is discharged from the combustion exhaust gas discharge port 6 to the outside, the central portion of the melting furnace is not in an oxidizing atmosphere, and therefore the graphite electrode 2 is not oxidized and consumed.

In the above embodiment, the cooling air passage 11 is formed directly in the overflow portion 1d of the tap hole 4, but in other embodiments, it is shown in FIGS. As shown in FIG.
At the bottom of the runner 14 formed over the
1'is embedded in a meandering manner to form a cooling air flow path 11, and cooling air 15 is sent to the cooling pipe 11 'from a cooling fan 13 and a cooling air supply pipe 12 so that substantially the entire overflow portion 1d is formed. The refractory may be cooled. The end portion 11a of the cooling pipe 11 'is open to the hot water outlet 4, and the cooling air 15 can be supplied into the hot water outlet 4. Also in this embodiment,
The same effects as those of the first embodiment can be obtained.

[0021]

As described above, in the overflow hot-melting type electric melting furnace of the present invention,
Since the cooling air flow path for cooling the refractory in the overflow portion is formed and the cooling air is flown through the cooling air flow passage to cool the inside of the refractory, the life of the refractory in the overflow portion is reduced. Is greatly extended.

Further, in the electric melting furnace of the present invention, the end portion of the cooling air flow path is opened to the tap hole to supply the cooling air, which has cooled the refractory, to the tap hole, and the refrigerating air melts it. Combustible gas generated from the material is burned in the tap hole, and the heat of combustion heats the melt flowing in the overflow portion. As a result, the melt in the tap hole maintains its fluidity and taps smoothly and satisfactorily.

Further, since the electric melting furnace of the present invention uses air for cooling the refractory, it is excellent in safety. That is, when water is used to cool the refractory, if the cooling water leaks into the furnace, there is a risk of steam explosion due to mixing with the melt, but in the case of air, such There is no danger.

In addition, the electric melting furnace of the present invention heats the melt which combustible gas satisfactorily burns and overflows only by supplying the cooling air to the space of the tap hole.
Unlike the conventional electric melting furnace, no special heating device such as an auxiliary electrode or an auxiliary burner is required, and running costs and initial costs can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an overflow tapping type electric melting furnace according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of an overflow portion of an electric melting furnace.

FIG. 3 is a schematic plan view of an overflow portion of an electric melting furnace in which a cooling air passage is formed by a cooling pipe.

FIG. 4 is a schematic cross-sectional view of the overflow section of FIG.

FIG. 5 is a schematic cross-sectional view of a conventional overflow melting type electric melting furnace.

FIG. 6 is a schematic cross-sectional view showing another example of the conventional overflow tapping type electric melting furnace.

[Explanation of symbols]

1d is an overflow part, 2 is an electrode, 4 is a tap hole, 8 is a melted material, 8a is a melted material, 9 is a flammable gas, 11 is a cooling air flow path, and 11a is an end part of the cooling air flow path.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kotaro Kato 1-3-23, Dojimahama, Kita-ku, Osaka, Osaka Prefecture Takuma Co., Ltd. (72) In-house, Miku Kawai 1-3-3, Dojimahama, Kita-ku, Osaka, Osaka No.23 Takuma Co., Ltd.

Claims (1)

[Claims] 1. A molten material (8) such as incinerated ash or dust from a refuse incinerator is melted by an electrode (2), and this molten material (8a) is made to overflow from a tap hole (4). In the overflow melting type electric melting furnace,
In the overflow portion (1d) of the tap hole (4), a cooling air flow passage (11) for cooling the refractory in the overflow portion (1d) is formed, and the cooling air flow passage (1) is formed.
Generated by melting the melted substance (8) by opening the end (11a) of 1) to the tap hole (4) and supplying cooling air (15) for cooling the refractory into the tap hole (4). An electric melting furnace, wherein the combustible gas (9) is burned in the tap hole (4).