JPH08285255A - Refining treatment for gas being generated in melting furnace, and waste melting furnace - Google Patents

Abstract

PURPOSE: To dispose tar in an exhaust gas by cracking at a high temperature by a method wherein in a shaft furnace type waste melting furnace, air is fed from an air feeding nozzle being provided in a refining zone upper than a waste stock level, and a flammable gas which ascends from the furnace lower part is partially burned. CONSTITUTION: For a melting furnace 1, a plurality of lower tuyeres 2 and upper tuyeres 3 are respectively provided around a furnace at a lower part of its shaft part (1a), and oxygen enriched air is fed from the lower tuyere 2 which is provided on a furnace bed part (1b). Also, air for combustion is fed into a furnace from the upper tuyere 3 which is provided on a bosh shaped part (1c) at on the top of the bed furnace bed part (1b). Also, the upper part of the shaft (1a) is made a refining zone, and a nozzle 4 which feeds air to an area higher than the stock level of an article to be charged is provided in the refining zone, and an injection port 5 for flammable dust being spread is provided on the top of the nozzle 4. Then, by partially burning the flammable gas which ascends from the lower part of the refining zone, tar in the furnace top gas is well disposed by cracking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a waste melting furnace for treating general waste or industrial waste, and more particularly to a method and an apparatus for reforming the gas generated from the waste melting furnace.

[0002]

2. Description of the Related Art The waste treatment in a waste melting furnace is a method in which general waste or industrial waste loaded in the furnace is dried, pyrolyzed, burned, and melted, and then taken out as slag. Is.

For example, in Japanese Patent Publication No. 60-11766, as shown in FIG. 2, a waste melting furnace 1 has a shaft-shaped furnace body having a circular cross section, and the waste is charged into the furnace. The coke, which is a fuel, is burned in order to dry, pyrolyze, burn and melt the product. Because of the coke burning,
The lower part of the furnace body is provided with a plurality of stages of tuyeres. Of these tuyeres, the lower stage tuyeres 2 located near the hearth blow the oxygen-enriched air and the upper stage of the lower stage tuyeres. Air is blown into the upper tuyeres 3 arranged in the.

In the operation of the waste melting furnace, combustible components in the charge are pyrolyzed in the furnace to generate a pyrolysis residue. The generated pyrolysis residue is burned by the air sent from the tuyere or is accumulated in the furnace, but the fine particles are not burned by the air sent from the tuyere After that, it scatters from the furnace as combustible dust and is treated in the secondary combustion chamber in the latter stage together with the exhaust gas.

[0005]

However, in the melting furnace, since the temperature of the exhaust gas at the top of the furnace is as low as 100 to 500 ° C,
Exhaust gas contains a large amount of tar. Therefore, when a secondary combustion chamber is installed, the duct in the middle is apt to be clogged with tar and periodical cleaning is required, and when recovering exhaust gas as fuel, a gas cleaning device such as a scrubber uses tar. Due to the inconvenience of blockage, the current situation is that fuel is not actually collected. Further, since the pyrolysis residue generated by the pyrolysis scatters as combustible dust, there is a disadvantage that the gasification efficiency deteriorates.

In view of this, the invention of the present application cracks the tar in the exhaust gas, which blocks the exhaust gas treatment equipment such as the exhaust gas duct and the gas cleaning device installed at the latter stage of the waste melting furnace, at a high temperature and scatters the combustible dust. The present invention provides a method for gasifying gas and a processing device therefor.

[0007]

According to the treatment method of the present invention, a reforming zone is provided above the stock level of a shaft of a melting furnace, and tuyeres for blowing air are provided in the reforming zone, and a reforming zone is provided from the bottom of the melting furnace. 100-500 ° C rising
Partial combustion of the gas in the reforming zone at 800 ° C
Adjusted as above and set the gas retention time in the reforming zone to 1
By securing at least 2 seconds, the cracking treatment of tar in the furnace top gas is sufficiently performed. The amount of air supplied to the reforming zone is controlled by a temperature indicating controller (TIC). It is also effective to add water vapor in order to accelerate the gasification of combustible dust. In addition, the gas to be recycled to the reforming zone and the combustible dust in the exhaust gas collected by the cyclone are sucked from the lower part of the cyclone, and the gas is supplied to the reforming zone together with air or an inert gas by the ejector to burn the combustible dust. Is gasified.

[0008] Further, most of the combustible dust which cannot be completely reacted in the reforming zone is collected by a cyclone installed in the middle of the exhaust gas duct, and is recycled to the reforming zone to further reduce the combustible dust content. A combustible gas can be provided.

The treatment apparatus according to the present invention is a waste melting furnace having a lower tuyere for blowing oxygen-enriched air into the lower part of the furnace body and an upper tuyere for blowing air into the furnace body. An air blowing tuyere is installed in the upper reforming zone.Furthermore, the combustible dust blowing port that returns the combustible dust collected by the exhaust gas dust removal device from the furnace top of the waste melting furnace to the reforming zone. May be provided in the reforming zone.

[0010]

According to the present invention, the tar-containing combustible gas rising from the lower part of the waste melting furnace is burned, the tar is decomposed, and the scattered combustible dust is recycled to the melting furnace and burned. Fewer combustible dust is also scattered.

[0011]

Embodiment An embodiment of the present invention will be described with reference to FIG.

As a waste treatment facility for carrying out the method for treating combustible dust according to the present invention, a melting furnace of a shaft furnace type is used, and the melting furnace 1 is provided with a waste device provided above the shaft portion 1a. It is configured so that the waste can be charged into the furnace by the charging device.

A plurality of lower tuyeres 2 and upper tuyeres 3 are provided around the furnace at the lower portion of the shaft portion 1a of the melting furnace 1. The lower tuyeres 2 are provided in the hearth 1b, and oxygen-enriched air is blown into the furnace from the lower tuyeres 2 in order to burn the coke that has descended to the bottom of the furnace. On the other hand, the upper tuyeres 3 are provided in the bosh section 1c above the hearth floor, and combustion air is blown into the furnace from the upper tuyeres 2. The upper tuyeres 2 may be provided in two or more stages.

A reforming zone is formed in the upper portion of the shaft 1a of the melting furnace 1, a nozzle 4 for injecting air is provided above the stock level of the charge, and flammable dust scattered further above the nozzle 4 is provided. Blow-in port 5 is provided.

Most of the combustible dust in the exhaust gas discharged from the furnace top is collected by a dust remover 6 such as a cyclone installed in the middle of the exhaust gas duct, and melted from the combustible dust blowing port 5 by an ejector 7. It is returned to the furnace and burned.

The amount of air blown from the nozzle 4 into the reforming zone and the amount of combustible dust blown into the reforming zone from the combustible dust inlet 5 are controlled by the temperature controller (TC) to adjust the opening of the regulating valve 8. Do it.

In the melting furnace, the waste material charged from the charging hopper on the upper part of the furnace body is dried as it descends in the furnace body, and then the combustible material is thermally decomposed to generate a thermal decomposition residue. The thermal decomposition residue burns in contact with the air blown from the upper tuyere, but the uncombusted thermal decomposition residue accumulates, and the fine thermal decomposition residue (combustible dust) is a combustible gas stream from the lower part of the furnace. Climbs up. In the reforming zone, the temperature of the combustible gas containing combustible dust is about 1
At 00 to 500 ° C, the components consist of about 50% combustible gas, about 30% tar, and about 20% combustible dust in terms of calories. Air is blown from the upper tuyere into the reforming zone to partially burn and reform. By adjusting the zone to about 800 ° C or higher, tar is cracked to CnHm or the like.

Combustible dust is decomposed by thermal decomposition and CO ₂
Gasification is promoted by a reaction such as + C → 2CO. As a result, the amount of combustible dust that scatters is reduced, and a high-calorie combustible gas with a small amount of combustible dust can be obtained.
Further, most of the combustible dust scattered in the exhaust gas is collected by the cyclone installed in the exhaust gas duct from the furnace top, and returned to the melting furnace from the combustible dust blowing port of the reforming zone and burned. As a result, the amount of combustible dust that scatters is reduced, and a high-calorie combustible gas with a small amount of combustible dust can be obtained.

[0019]

The effects of the present invention are as follows.

(1) According to the present invention, the tar in the gas rising from the lower part of the furnace is cracked at a high temperature in the reforming zone to decompose the tar in the exhaust gas, so that it is provided in the latter stage of the blast furnace. Exhaust gas treatment equipment such as exhaust gas ducts and gas cleaning equipment will not be closed by tar.

(2) Since the combustible dust contained in the exhaust gas is collected, recirculated to the reforming zone and burned, the gasification efficiency is good.

(3) When the exhaust gas of the melting furnace of the present invention is completely combusted in the secondary combustion furnace installed in the latter stage, the combustion is stable because the exhaust gas temperature is high, and the combustible dust is extremely small. Therefore, combustion is stable and pollution problems are reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of a waste melting furnace according to the present invention.

FIG. 2 is a schematic view of a conventional waste melting furnace.

[Explanation of symbols]

1 melting furnace, 1a shaft, 1b hearth, 1
c Morning glory, 2 lower tuyeres, 3 upper tuyeres, 4
Nozzle, 5 flammable dust inlet, 6 dust remover,
7 ejector, 8 adjusting valve

Claims (4)

[Claims] 1. A flammable material which blows air into a furnace from an air blowing nozzle provided in a reforming zone above a stock level of waste in a shaft furnace type waste melting furnace and rises from a lower part of the furnace. A method for reforming a gas generated from a melting furnace, which comprises partially burning the gas. 2. Exhaust gas containing combustible dust discharged from the top of a shaft furnace type waste melting furnace is dedusted,
The method for reforming a gas generated from a melting furnace according to claim 1, wherein the collected combustible dust is returned to the reforming zone and burned. 3. A waste melting furnace having a lower tuyeres for blowing oxygen-enriched air into the lower part of the furnace body and an upper tuyeres for blowing air, and reforming above the furnace body and above the stock level of waste. A waste melting furnace characterized in that an air blowing nozzle is provided in the zone. 4. The reforming zone is provided with a combustible dust blowing port for returning the combustible dust collected by the exhaust gas dust removing device from the furnace top of the shaft furnace type waste melting furnace to the reforming zone. The waste melting furnace according to claim 3, wherein: