JP2000171016A - Waste melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste melting furnace, melting waste directly without incinerating the same and reducing the amount of consumption of fuel, such as coke or the like. SOLUTION: A waste melting furnace is provided with a charging device 2 of waste and auxiliary materials, such as coke, limestone and the like, at the top of the furnace and a single stage or plurality of stages of tuyeres 3, 4, arranged in a shaft furnace 1. A heating coil 10, excited by AC current to heat coke, piled on a hearth 7, through induction heating, is installed around the outer periphery of lower part of the shaft furnace while the heating coil 10 is excited by AC current to heat the coke 12, piled on the hearth 7, through induction heating and melt unburnt matters in the waste by contacting them with the coke 12 under the condition of a high-temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for directly melting slag by directly melting waste such as municipal solid waste, industrial waste, sludge, incinerated ash from municipal solid waste, and waste buried in landfill waste. It relates to the waste melting furnace to be manufactured.
The slag produced by the waste melting furnace of the present invention can be used for civil engineering materials, road pavement materials, concrete aggregates, and the like.

[0002]

2. Description of the Related Art At present, most waste is treated by an incineration method, but the incineration method has a drawback that a disposal site for incinerated ash is required. Particularly in metropolitan areas, it is difficult to secure a disposal site for incinerated ash.
There is an increasing need to dissolve incinerated ash from waste in a manner that allows volume reduction and further recycling.

[0003] As a method of melting incinerated ash of waste, a method of melting in an arc furnace is disclosed in Japanese Patent Publication No. 4-81084. Also, a method of directly melting waste in a shaft furnace (vertical furnace) without incineration is disclosed in Japanese Patent Publication No. 60-1.
No. 1766 discloses this.

[0004]

However, in the former arc furnace method, waste is once incinerated and then melted, so that two-stage treatment is required, expensive graphite electrode rods are largely worn, and arc discharge is difficult. There is a problem such as noise generated from the sound. Further, the latter method of directly melting in a shaft furnace has a problem that a fuel such as coke is required. An object of the present invention is to provide a waste melting furnace which directly melts waste without incineration and reduces the consumption of fuel such as coke in order to solve the above problems.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a device for charging waste and co-materials such as coke and limestone at a furnace top, and a single-stage or multiple-stage shaft furnace. A waste melting furnace having a tuyere disposed therein, wherein a heating coil for supplying an alternating current for induction heating of coke deposited on the hearth is provided on an outer periphery of a lower part of the shaft furnace, and the tuyere is disposed from the tuyere. The combustibles of the waste are burned by the supplied air, and the incombustibles in the waste are brought into contact with the coke heated to a high temperature state by the induction heating and melted.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for directly melting waste such as municipal waste in a shaft furnace by drying and burning the shaft, the bosh section and the upper part of the hearth with air blown from the tuyere. Then, high-temperature coke, which is induction-heated by a heating coil installed in the lower part of the hearth, and incinerated ash are brought into contact and melted. In the prior art, coke was burned at the hearth with oxygen-enriched air blown from the lower tuyere, and the incineration ash was melted by the combustion heat. Consumption can be reduced. Furthermore, the oxygen added to the air blown from the lower tuyere can be reduced or made unnecessary. In addition, as a heating method using electricity, there is a method such as electric heating, but it is necessary to install electrodes through the furnace wall of the melting furnace, and the structure becomes complicated, and furthermore, replacement of worn out electrodes is complicated. However, in the case of induction heating, there is no such problem.

[0007] Further, in comparison with a case where incinerated ash is melted in an arc furnace, in a shaft furnace type melting furnace using coke, the furnace can be set to a reducing atmosphere, and lead and the like in the slag after melting. Since it is known to volatilize and reduce heavy metals, there is no concern about adverse effects on the environment when slag is used effectively. Therefore, the present invention is a waste melting furnace having the advantages of using a shaft furnace while reducing the heavy metals in slag while using electricity.

[0008]

FIG. 1 shows an embodiment in which waste is directly melted using coke as an example of melting the waste. In FIG. 1, coke and limestone as waste and by-products are charged from a furnace upper part of a shaft furnace 1 into a charging apparatus 2.
It is charged from. Municipal waste was disposed of as waste.
Table 1 shows the properties of the melted municipal solid waste.

The shaft furnace 1 comprises a shaft portion 5, a bosh section 6, and a hearth section 7, and an upper tuyere 3 provided around the bosh section and a lower tuyere 4 provided around the hearth section.
Is supplied with air. The waste disposal amount is 560kg /
h, coke and limestone are each about 1% and 6% of the waste, air was supplied to 400 Nm ³ / h from the upper tuyere 200 Nm ³ / h, from the lower tuyeres.

The waste, coke and the like charged into the melting furnace form a packed bed in the furnace, and the combustibles of the waste are burned by the air blown from the upper tuyere 3 and the lower tuyere 4. The combustion gas rises in the melting furnace from the bottom of the furnace, and the waste is preheated, dried and thermally decomposed by the sensible heat of the combustion gas. Steam, pyrolysis gas and fine dust generated in the process of drying and pyrolysis of the waste are discharged from the gas discharge pipe 8.
On the other hand, the ash and non-combustion of waste, coke, and limestone are heated to a high temperature and descend to the hearth 7.

An alternating current is applied from a high-frequency power supply 11 to a heating coil 10 installed on the outer periphery of the floor to inductively heat the coke 12 deposited on the furnace floor, and to cause the coke 12
The ash in the waste and the incombustibles are brought into contact with and melted.
The ash and the non-combustibles are heated from 1300 ° C. to 1550 ° C. to be in a molten state, and discharged from the slag discharge holes 9 to the outside of the furnace. Limestone and lime CaO and the ratio of the silicic acid content of SiO ₂ basicity namely slag slag is 0.7 or more,
It is added to adjust the fluidity of the molten slag. In addition, as the electric power for induction heating, the electric power generated by burning the gas discharged from the gas discharge pipe and generating steam by the boiler using the heat was used.

The molten bear slag discharged from the slag discharge port 9 is water-cooled to be fine sand-like particles. Also,
Slag in the molten state contains molten metal,
Metal also becomes fine particles like slag. Slag is used as aggregate or civil engineering material for secondary concrete products such as interlocking blocks.

Although coke is used in this embodiment, it is also possible to use a graphite block. It is also possible to burn coke near the lower tuyere by adding a small amount of oxygen to the lower tuyere to melt the incombustibles, and to raise and keep the temperature of the incombustibles melted by the heat of induction heating of the coke. It is. The optimal rate of coke combustion and induction heating can be selected depending on the amount of power available.

FIG. 2 shows a conventional shaft furnace type direct melting furnace of the prior art. The same members as those of the melting furnace of the present invention shown in FIG. When the same waste is treated in the conventional melting furnace shown in FIG. 2, 6% of the coke is required with respect to the waste, and it is necessary to supply oxygen by enriching 45 Nm ³ from the lower tuyere. Was. Compared with this conventional method, the waste melting furnace of the present invention shown in FIG. 1 can reduce coke consumption and oxygen.

[0015]

[Table 1] Properties of waste

[0016]

According to the present invention, the following effects can be realized. 1) Compared with the method in which the waste is incinerated and then melted in an arc furnace, the waste melting furnace according to the present invention can directly melt the waste, and the equipment configuration is simple and economical. Further, not only is it unnecessary to handle the incineration ash of the arc furnace type, but also the thermal efficiency is higher than the method of once cooling the incineration ash and melting it in an arc furnace.

2) When waste is directly melted in a waste melting furnace without incineration, coke is induction-heated to melt ash, thereby reducing coke consumption and reducing the amount of air blown from tuyeres. It is possible to reduce or eliminate the enriched oxygen. Further, the temperature of the molten slag can be easily adjusted by adjusting the power input amount of the induction heating.

3) As a heating method using electricity in a shaft furnace type melting furnace, there is a method such as energization heating. However, it is necessary to install electrodes through the furnace wall of the melting furnace, and the structure becomes complicated. In addition, replacement of worn electrodes is complicated. In contrast, induction heating does not have such a problem.

4) Compared to the case where incinerated ash is melted in an arc furnace, in a shaft furnace type melting furnace using coke, the inside of the furnace can be set to a reducing atmosphere, and lead and the like in the slag after melting. Can be reduced by volatilization of heavy metals, and there is no concern about adverse effects on the environment when slag is used effectively. Therefore, the present invention is a waste melting furnace having the advantages of using a shaft furnace while reducing the heavy metals in slag while using electricity.

5) As the electric power for induction heating the coke, it is not necessary to purchase power from the outside by generating electricity using the calorific value of the waste and using it effectively.

6) By recycling the slag after the melting treatment, not only is the slag disposal site unnecessary, but also natural destruction due to mining of natural sand can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a shaft furnace type direct heating furnace according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft furnace 2 Charging device 3 Upper tuyere 4 Lower tuyere 5 Shaft part 6 Bosh part 7 Furnace floor part 8 Gas exhaust pipe 9 Slag exhaust port 10 Heating coil 11 High frequency power supply 12 Coke

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K061 AA16 AB03 AC01 AC02 AC03 CA08 CA13 DA03 DB16 4D004 AA02 AA36 AA46 BA02 BA03 CA26 CA29 CB02 CB33 CB50 CC02 CC11

Claims (1)

[Claims] 1. A waste melting furnace comprising a furnace top and a device for charging waste and co-materials such as coke and limestone, and a single-stage or multiple-stage tuyere disposed in a shaft furnace, wherein Waste melting furnace with a heating coil installed on the outer periphery of the lower part of the shaft furnace to supply an alternating current for induction heating of coke deposited in the furnace.