JP3762450B2 - Control method of air blowing rate of upper tuyere of waste melting furnace - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for operating a shaft furnace type waste melting furnace for treating general waste or industrial waste, and more particularly to a method for controlling the upper tuyere air blowing rate of a waste melting furnace.
[0002]
[Prior art]
Waste treatment using a shaft furnace type waste melting furnace takes out the waste as slag through the process of drying, pyrolysis, combustion and melting of general waste or industrial waste charged in the furnace. is there.
[0003]
For example, in Japanese Examined Patent Publication No. 60-11766, as shown in FIG. 3, the waste melting furnace 1 has a shaft-type furnace body having a circular cross section, and the waste charged in the furnace is dried. The coke as a fuel is burned for pyrolysis, combustion and melting. For the coke combustion, a plurality of tuyere are provided in the lower part of the furnace body, and among these tuyere, the lower tuyere 2 disposed near the hearth part blows air enriched with oxygen, The upper tuyere 3 disposed on the lower tuyere is designed to blow air.
[0004]
In the operation of the waste melting furnace, the flammable residue generated by the thermal decomposition of the combustible material in the charge is burned by the air blown from the upper tuyere, but the flammable residue burning rate is combustible. Since it is smaller than the residue generation rate, unburned combustible residue accumulates in the furnace. Among the flammable residues, fine flammable residues are scattered as flammable dust from the top of the furnace without being burned in the furnace by oxygen sent from the tuyere.
[0005]
[Problems to be solved by the invention]
However, the charge above the combustible residue layer is dried and pyrolyzed by the combustion gas generated by the partial combustion of the combustible residue, and the volume of the charge is reduced due to the volume reduction. The volume of the combustible residue is reduced due to combustion and scattering of the combustible residue, and the charge falls. However, since the flow resistance of the charge is non-uniform in the cross section of the furnace, the combustion gas flow tends to be non-uniform and pyrolysis The deposit thickness of the residue layer is partially different, and as a result, the load unloading tends to be uneven.
[0006]
If the load of the charged material becomes uneven, unloading failure or blow-through due to cavitation occurs, and stable furnace operation becomes very difficult.
[0007]
Also, if the proportion of combustible dust that scatters increases due to unstable furnace operation, the proportion of combustible materials such as carbon and hydrogen that can be used in the furnace will decrease, so it will be charged with waste. It was necessary to increase the proportion of the auxiliary materials such as coke.
[0008]
Further, the scattered combustible dust is completely combusted in the secondary combustion chamber at the subsequent stage. However, if the amount of scattering fluctuates, unburned CO is generated and clinker is generated, which is not preferable.
[0009]
Accordingly, the present invention provides a method for controlling the upper tuyere air blowing amount of the melting furnace that stabilizes the furnace operation by uniforming the unloading of the charge in the shaft furnace type waste melting furnace. is there.
[0010]
[Means for Solving the Problems]
The method for controlling the amount of air blown from the upper tuyere of the waste melting furnace according to the present invention is provided with a plurality of tuyere at the lower part of the furnace body, and oxygen enriched air is supplied from the lower tuyere of the tuyere. In the method for controlling the amount of air blown in the upper tuyere installed in the plane direction of the shaft furnace type waste melting furnace, the air is blown into each tuyere of the upper tuyere. A shut-off valve that shuts off air and a flow rate adjusting valve that regulates the amount of air are connected, and the shut-off valve is periodically opened and closed at regular intervals according to a preset schedule to blow air into each tuyere and Stopping is performed periodically and the amount of air blown from each upper tuyere is adjusted.
[0011]
[Action]
According to the present invention, the amount of air blown into a plurality of upper tuyere installed in the height direction and the plane direction is increased or decreased for each tuyere and the gas flow in the furnace is actively stirred. Unloading becomes uniform. In addition, since the charge is usually not uniform in the cross-sectional direction, the gas flows in a biased direction toward the place where the charge flows most easily, but the increase or decrease in the air suppresses the buoyancy of the charge when it is reduced. In order to promote unloading, there is also an effect of suppressing the deviation of the gas flow.
[0012]
【Example】
Embodiments of the present invention will be described with reference to the drawings.
[0013]
A shaft furnace type melting furnace 1 to which the present invention is applied has a lower tuyere 2 around the hearth part 1a, and an upper tuyere 3 is arranged around the morning glory part 1b above the lower tuyere 2. ing. In the present embodiment, the upper tuyere 3 is branched from the header pipe 5, and the upper tuyere 3a and the lower tuyere 3b are provided in two stages and four in the plane direction. The closer the installation level of the upper tuyere 3a is to the dry completion level of the charge, the more effective. Air is supplied to the upper tuyere 3 a and the lower tuyere 3 b of the upper tuyere 3, and air enriched with oxygen is supplied to the lower tuyere 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 shut-off valve 6 according to a preset time schedule.
[0014]
In the present embodiment, the air blowing amount of the upper tuyere 3a and the lower tuyere 3b is changed. Switching of the air blowing will be described with reference to the time chart shown in FIG .
[0015]
When air blowing is started, No. No air is blown into one tuyere (upper tuyeres on the upper and lower sides, the same shall apply hereinafter), and the remaining No. 2-No. Blow the same amount of air through the four tuyere. After 10 minutes, no. No. 2 at the same time the air blowing is stopped at the two tuyere. Start 1-air blow. After 10 minutes, no. No. 3 at the same time the air blowing was stopped for only the three tuyere. Start the 2 tuyere air blow again. After 10 minutes, no. No. 4 at the same time the air blowing was stopped at only the four tuyere. Start the 3 tuyere air blow again. After a further 10 minutes, no. At the same time as stopping the air blowing for only one tuyere, Start the 4 tuyere air blow again. The above operation is performed periodically. In addition, No. 1-No. 4 birds mouth blown and regardless of the stop of the total air volume per unit of time the upper tuyeres, from the air amount required for reaction in the reactor, is constant as shown in FIG.
[0016]
For example, in the case of a melting furnace having a processing rate of 20 t / day, a number of tuyere stages of 2, and a number of tuyeres of 4 per stage, the specific values of the air blowing amount and time are each blown with a total air volume of 500 Nm ³ / h. As a result of repeating the pattern in which the tuyere was sequentially blown and stopped for 10 minutes, no blow-through or unloading failure occurred.
[0017]
【The invention's effect】
The effects of the present invention are as follows.
[0018]
(1) By periodically changing the amount of air from the upper tuyere, the pyrolysis residue layer thickness in the furnace is controlled, and the air pressure loss is lowered and stabilized, so the buoyancy of the charge is reduced and blown through. It has the effect of suppressing unsteady phenomena such as unloading defects.
[0019]
(2) As a result of (1), when recovering energy by power generation, there is an effect of stabilizing the power generation amount.
[Brief description of the 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 an upper tuyere portion of a waste melting furnace used in an embodiment of the present invention.
FIG. 3 is a time chart of an embodiment 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 tuyere, 3 upper tuyere, 3a upper tuyere, 3b lower tuyere, 4 flow control valve, 5 header pipe, 6, shutoff valve

Claims (1)

A shaft furnace type waste melting furnace is provided with a plurality of tuyere at the bottom of the furnace body, in which oxygen-enriched air is blown from the lower tuyere and air is blown from the upper tuyere. In the control method of the air blowing amount of the upper tuyere installed in the plane direction,
Wherein connecting the shut-off valve and flow control valve for adjusting the amount of air that blocks air blown into the tuyeres of the upper tuyere, and periodically opened and closed at regular time intervals according to the schedule set the shut-off valve in advance A method for controlling the amount of air blown from the upper tuyere of the waste melting furnace, characterized by periodically blowing and stopping air for each tuyere and adjusting the amount of air blown from each upper tuyere.

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