JPH08285250A - Disposal of fllamable dust of melting furnace for waste - Google Patents

Abstract

PURPOSE: To improve the heat efficiency, and reduce the consumption of a subsidiary fuel such as coke, etc., by a method wherein flammable dust is caught, and the caught flammable dust is fed from an upper tuyere for a shaft furnace type waste melting furnace which has an upper tuyere and lower tuyere. CONSTITUTION: Among residues being generated due to a pyrolysis of burnable articles in articles charged into a melting furnace 1, flammable dust which spreads from the furnace top is introduced to a dust separator 5 through an exhaust gas piping 4 at the furnace top, and caught. The caught flammable dust is temporarily stored in a flammable dust hopper 6, and when a specified quantity of dust is stored in the hopper 6, the dust is cut by a cut device 7 being arranged on the bottom of the hopper 6, and is fed to a distributor 11. The dust which is fed to each upper tuyere 3 by the distributor 11 is fed into the melting furnace 1 together with air. Thus, by catching flammable dust and burning it in front of the upper tuyere, the consumption of a subsidiary fuel such as coke, etc., can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a shaft furnace type waste melting furnace for pyrolyzing and melting general municipal solid waste and various industrial wastes, and more particularly to a method for operating a waste melting furnace of a shaft furnace type. The present invention relates to a method for treating combustible dust in a waste melting furnace for treating combustible residue (dust) generated as a result of thermal decomposition of combustible components.

[0002]

2. Description of the Related Art Waste treatment in a shaft furnace type waste melting furnace is a process of drying, pyrolyzing, burning, and melting general waste or industrial waste loaded in the furnace, It is taken out as slag.

The melting furnace is a shaft type furnace body having a circular cross section, and burns coke which is a fuel in order to dry, pyrolyze, burn and melt the waste charged in the furnace. . Due to the coke combustion, a plurality of stages of tuyeres are provided in the lower part of the furnace body, and among these tuyeres, the lower stage tuyeres arranged in a single stage or multiple stages near the hearth part are enriched with oxygen. Air is blown, and air is blown into the upper tuyeres arranged in a single stage or a plurality of stages on the lower tuyeres.

In the operation of the waste melting furnace, combustible components in the charge are thermally decomposed in the furnace to generate a 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 Then, it is scattered as combustible dust from the furnace.

As a technique for treating the above-mentioned scattered flammable dust, the present applicant has disclosed in Japanese Patent Laid-Open No. 340520/1993 that suppresses fluctuations in the amount of flammable dust generated after thermal decomposition in a waste melting furnace. In order to achieve stable energy recovery by suppressing fluctuations in the amount of exhaust gas and temperature in the secondary combustion furnace, and to stabilize the exhaust gas treatment process, we proposed a treatment technology using a waste melting furnace.

In the waste melting furnace, as shown in FIG. 2, the exhaust gas containing combustible dust scattered from the melting furnace 1 is burned by a dust remover 5 such as a cyclone provided in the exhaust gas pipe 4. Are collected, and the collected combustible dust is temporarily stored in the combustible dust hopper 6. The flammable dust hopper 6 is provided with a flammable dust cutting device 7, and the flammable dust cut by the cutting device 4 is sent to the secondary combustion furnace 12 and burned.

[0007]

Since the treatment technique described in the above publication can suppress fluctuations in the exhaust gas amount and temperature of the secondary combustion furnace, it suppresses fluctuations in the system after the secondary combustion furnace. You can However, since the operation of the melting furnace itself in the preceding stage of the secondary combustion furnace has not been improved, the thermal efficiency of the melting furnace (partial combustion ratio of the charge) is no different from the conventional one.

Therefore, the present invention reduces the amount of auxiliary fuel such as coke used by improving the thermal efficiency of the shaft furnace type waste melting furnace, and installs a gas recovery device instead of the secondary combustion furnace. It is intended to provide a method for treating combustible gas in a waste melting furnace, which enables treatment of combustible dust even in the case.

[0009]

DISCLOSURE OF THE INVENTION In the operation of a waste melting furnace having an upper stage tuyeres and a lower stage tuyeres at the lower part of a shaft furnace type waste melting furnace, the present invention is a combustible material that scatters from the top of the melting furnace. Dust is collected by a dust remover such as a cyclone, the collected combustible dust is blown together with air from the upper tuyeres, and the combustible dust is burned in front of the upper tuyeres,
It is used not only as a heat source for drying the charge, but also for raising the temperature of the charge. Since the recovered combustible dust burns and becomes a heat source, auxiliary fuel such as coke, which becomes a heat source for drying and melting, can be reduced.

Although it is considered that combustible dust is blown into the lower tuyeres, the collected combustible dust is 10
0-500 ^. Because of the low temperature and fineness of C, CO ₂
Since it reacts with the gas and easily causes an endothermic reaction, it lowers the combustion temperature and hinders melting. Therefore, it is preferable that the combustible dust be supplied to the upper tuyeres that mainly burn the charge.

[0011]

[Operation] After the combustible dust scattered from the top of the melting furnace is collected, the collected combustible dust burns in front of the upper tuyere, and this combustion is used for drying and raising the charge. Since it serves as a heat source for heating, it has become possible to reduce auxiliary fuel such as coke, which has been a heat source for drying and melting the charge in the past.

[0012]

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 flammable dust according to the present invention, a shaft furnace type melting furnace is used. The melting furnace 1 is configured so that waste can be charged into the furnace by a waste charging device (not shown) provided on the upper portion of the shaft portion 1a.

A plurality of lower tuyeres 2 and upper tuyeres 3 are arranged 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 come to the bottom of the furnace. On the other hand, the upper tuyeres 3 are provided in the bosh section 1c at the upper part of the hearth part, and the recovered combustible dust is blown into the furnace from the upper tuyeres 2 together with the air. The upper tuyeres may be provided in two or more stages.

Combustible dust generated in the melting furnace 1 and scattered from the furnace top is configured to be collected by a dust remover 5 such as a cyclone provided in the exhaust gas pipe 4 from the furnace top. The collected combustible dust is combustible dust hopper 6
Stored temporarily in. A cutting device 7 for cutting out the combustible dust to be supplied to the upper tuyere 2 is disposed below the combustible dust hopper 6.

The flammable dust cut out by a predetermined amount by the cutting device 7 is mixed with the carrier air from the blower 8 by the mixer 9 and is transported to the distributor 11 through the transport pipe 10, and the distributor 11 is transported. The combustible dust thus obtained is distributed to each upper tuyere 3.

Next, a method of treating combustible dust according to the present invention will be described.

Of the residue generated by the thermal decomposition of the combustible material in the charging furnace 1 in the charging furnace, the combustible dust scattered from the furnace top passes through the exhaust gas pipe 4 at the furnace top to the dust remover 5. guided by,
Collected. The combustible dust collected by the dust remover 5 is temporarily stored in the combustible dust hopper 6.

When a predetermined amount of combustible dust is stored in the combustible dust hopper 6, the combustible dust is cut out by a cutting device 7 arranged below the combustible dust hopper 6 and is blown by a blower 8. The carrier air is mixed with the mixer 11 and sent to the distributor 11. Note that when the temperature of the combustible dust is high, the combustible dust may be burned by the carrier air, so an inert gas is used instead of the air.

The combustible dust distributed by the distributor 11 for each upper tuyere 3 is blown into the melting furnace 1 together with air. The amount of blown air is set in consideration of the balance of the reaction in the furnace of the melting furnace 1. The combustible dust blown into the furnace is burned in front of the tuyere to serve as a heat source for drying the charge and also as a heat source for raising the temperature of the charge.

[0021]

The effects of the present invention are as follows.

(1) Combustible dust scattered from the top of the waste melting furnace is collected, blown into the furnace with air from the upper tuyeres of the melting furnace into the furnace, and burns in front of the upper tuyeres. As a result, it serves as a heat source for drying the charge and also as a heat source for raising the temperature of the charge, so that it is possible to reduce the amount of auxiliary fuel such as coke that is the heat source of the melting furnace.
The coke ratio (kg of coke per ton of waste) was reduced from 40 to 50 from 70 to 80 in the past.

(2) In the prior art, when the combustible dust scattered from the top of the melting furnace was blown into the secondary combustion chamber, it was necessary to treat about 50% of the ash as fly ash. Since it is not necessary to blow combustible dust scattered from the top of the melting furnace into the secondary combustion chamber, it is recycled and blown into the melting furnace, and most of it is discharged as slag from the bottom of the furnace. Can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a waste treatment facility for treating combustible dust according to the present invention.

FIG. 2 is an explanatory view of a conventional waste melting furnace.

[Explanation of symbols]

1 shaft furnace type melting furnace, 2 lower stage tuyeres, 3 upper stage tuyeres, 4 exhaust gas piping, 5 dust remover, 6 combustible dust hopper, 7 cutting device, 8 blower, 9 mixer, 10 transport pipe, 11 distribution Vessel, 12 secondary combustion furnace

Claims (1)

[Claims] 1. A shaft melting furnace waste melting furnace having an upper tuyeres and a lower tuyeres, wherein scattered flammable dust is collected and the collected combustible dust is blown from the upper tuyeres. A method for treating combustible dust in a shaft furnace type waste melting furnace.