JPH08285248A - Control of air feeding quantity for upper tuyere of waste melting furnace - Google Patents

Abstract

PURPOSE: To even the load sagging of charged articles, and stabilize the operation of a furnace by periodically performing the increase/decrease of air feeding quantities for respective tuyeres for an upper tuyere, a plurality of which are provided in the planar direction, at every specified time for a shaft furnace type waste melting furnace. CONSTITUTION: For a shaft furnace type melting furnace 1, a lower tuyere 2 is arranged around a furnace bed part (1a), and an upper tuyere 3 wherein, e.g. four units of upper and lower tuyeres 3a, 3b are provided in the planar direction, is arranged around a bosh-shaped part (1b), on the top of the lower tuyere 2, and air is fed to the upper tuyere 3, and air being enriched with oxygen is fed to the lower tuyere 2. Then, the air feeding quantities for the upper and lower tuyeres 3a, 3b are changed. Ip this case, when the air feeding is started, air is not fed to No.1 tuyere, and the same quantity of air is fed from remaining tuyeres. Then, after a specified period of time, e.g. 10 minutes have passed, an air feeding is started for No. 2 tuyere only. By periodically performing such motions, the thickness of a pyrolytic residue in the furnace is adjusted, and a ventilation pressure loss is reduced.

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 shaft furnace type waste melting furnace for treating general waste, industrial waste, etc., and particularly to controlling the amount of air blown into the upper tuyeres of the waste melting furnace. Regarding the method.

[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.

For example, in Japanese Patent Publication No. 60-11766, as shown in FIG. 3, the 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, the combustible residue generated by the thermal decomposition of combustible components in the charge is burned by the air blown from the upper tuyere, but the combustible residue burning rate is Is less than the combustible residue generation rate, unburned combustible residues are deposited in the furnace. Among the combustible residues, fine combustible residues are not burned in the furnace by the oxygen sent from the tuyere, but fly along the air flow and are scattered as combustible dust from the furnace top.

[0005]

However, the combustion gas generated by the partial combustion of the combustible residue causes the charge on the upper part of the combustible residue layer to be dried and pyrolyzed to reduce its volume. The charge drops, and the volume is reduced due to the burning and scattering of combustible residue, and the charge drops,
Since the ventilation resistance of the charge is uneven in the cross section of the furnace, the flow of the combustion gas is likely to be uneven, and the deposition thickness of the pyrolysis residue layer is partially different, resulting in the unloading of the charge. Also tends to be non-uniform.

[0006] If the unloading of the charge becomes uneven, deficiency of unloading and blow-through will occur due to cavitation, making stable furnace operation extremely difficult.

If the proportion of combustible dust scattered due to unstable furnace operation increases, the proportion of combustibles such as carbon and hydrogen available in the furnace decreases.
It was necessary to increase the proportion of by-products such as coke charged with the waste.

Further, the scattered combustible dust is completely combusted in the secondary combustion chamber in the latter stage, but when the scattered amount changes,
Unburned CO is generated and clinker is generated, which is not preferable.

Therefore, according to the present invention, the unloading of the charge in the shaft furnace type waste melting furnace is made uniform,
It is intended to provide a method for controlling the upper stage tuyere air blowing amount of a melting furnace for stabilizing the furnace operation.

[0010]

[Means for Solving the Problems] In controlling the air blowing amount of upper tuyeres installed in a plane direction of a shaft furnace type waste melting furnace, the air blowing amount of each tuyere of the upper tuyeres is controlled. It is characterized in that the gas flow in the furnace is made uniform by periodically increasing and decreasing it at regular intervals.

[0011]

According to the present invention, since the air blowing amount of a plurality of upper tuyeres installed in the height direction and the plane direction is increased or decreased for each tuyere, the gas flow in the furnace is positively stirred.
The unloading of the charge becomes uniform. Also, the charge is usually
Since the cross-sectional direction is not uniform, the gas becomes a biased flow toward the place where the charge most easily flows, but the increase or decrease of the air suppresses the buoyancy of the charge when it is reduced and promotes unloading, It also has an effect of suppressing the deviation of the gas flow.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

A shaft furnace type melting furnace 1 to which the present invention is applied has a lower stage tuyere 2 around a hearth portion 1a, and an upper stage tuyere 3 is provided above the lower stage tuyere 2 around a bosh section 1b. It is located in. In this embodiment, the upper tuyeres 3 are branched from the header pipe 5, and the upper tuyeres 3a and the lower tuyeres 3b are two-tiered,
Four are provided in the plane direction. The effect that the installation level of the upper tuyere 3a is closer to the drying completion level of the charge is more effective. Air is supplied to the upper tuyeres 3a and the lower tuyeres 3b of the upper tuyeres 3, and the air enriched with oxygen is supplied to the lower tuyeres 2 and blown into the melting furnace 1. The amount of air or oxygen-enriched air blown into the furnace by each tuyere opens and closes the shutoff valve 6 according to a preset time schedule.

In this embodiment, the amount of air blown into the upper tuyeres 3a and the lower tuyeres 3b is changed, but FIG.
Switching of air blowing will be described with reference to the time chart shown in FIG.

When the blowing is started, the No. No air is blown into one tuyere (upper and lower tuyere. The same applies below),
The remaining No. 2 to No. Blow the same amount of air from the 4 tuyeres. After 10 minutes, No. No. 2 at the same time when air blowing was stopped for only two tuyere. Start blowing air from one tuyere. After 10 minutes, No. No. 3 at the same time when the air blowing was stopped only for the 3 tuyeres. Re-inject the tuyere with air. After 10 minutes, No. No. 4 at the same time when the air blowing was stopped only for the 4 tuyeres. Start blowing air into the 3 tuyere again. After a further 10 minutes, No. No. 1 at the same time when air blowing was stopped for only one tuyere. Re-introduce the 4-tuyere air blowing. The above operation is periodically performed. In addition, No. 1 to No. The total air volume per unit time of the upper tuyeres is constant as shown in FIG. 2 regardless of the air volume required for the reaction in the furnace regardless of the blowing of the four tuyere and its stop.

Specific values of the amount of air blown in and the time are, for example, a throughput of 20 t / day, and in the case of a melting furnace having two stages of tuyeres and four tuyeres / stage, the air volume is 500 Nm ³ / h. As a result of repeating the pattern of sequentially blowing each tuyere for 10 minutes to blow, no blow-through and unloading failure occurred.

[0017]

The effects of the present invention are as follows.

(1) By periodically changing the amount of air from the upper tuyeres, the thickness of the pyrolysis residue layer in the furnace is controlled, and the ventilation pressure loss is reduced and stabilized, so that the buoyancy of the charging material is reduced. It has the effect of suppressing unsteady phenomena such as reduction, blow-through, and defective loading.

(2) As a result of (1), there is an effect of stabilizing the amount of power generation when energy is recovered by power generation.

[Brief description of drawings]

FIG. 1 is a schematic view of a waste melting furnace used in an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the upper tuyeres of the waste melting furnace used in the embodiment of the present invention.

FIG. 3 is a time chart of an example of the present invention.

FIG. 4 is a schematic view of a conventional waste melting furnace.

[Explanation of symbols]

1 shaft furnace type melting furnace, 2 lower stage tuyeres, 3
Upper tuyeres, 3a Upper tuyeres, 3b Lower tuyeres, 4
Flow control valve, 5 header pipes, 6, shutoff valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F23G 5/50 ZAB F23G 5/50 ZABH

Claims (1)

[Claims] 1. In a method for controlling the air blowing amount of upper tuyeres installed in a plurality of shaft furnace type waste melting furnaces in a plane direction, the air blowing amount of each tuyere of the upper tuyer is increased or decreased for a certain period of time. A method for controlling the amount of air blown into the upper tuyeres of a waste melting furnace, which is characterized in that it is periodically performed every time.