JP2002349818A - Combustible dust injection method for waste melting furnace - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To directly measure the temperature in the vicinity of a portion where a difference in airflow resistance in the cross-sectional direction of a dry distillation residue is likely to occur, identify the generation location early, and combustible dust to the vicinity of the generation location. By controlling (increasing) the amount of air blown, the difference in the ventilation resistance in the cross-sectional direction of the dry distillation residue is eliminated early without increasing. SOLUTION: The combustible dust scattered from the furnace top of the waste melting furnace 1 is collected, and the collected combustible dust is sent from a blowing tuyere 10 of the waste melting furnace 1 to a coke bed at room temperature oxygen-enriched air. Alternatively, in the method of blowing together with the high-temperature air, a space is provided above the tuyere 10 for blowing the combustible dust of the waste melting furnace 1 and in the cross-sectional direction of the furnace body filled with the object to be treated. Multiple thermometers 1 installed
The temperature in the furnace is measured in 2, and when the measured temperature becomes equal to or higher than a preset temperature, the amount of combustible dust blown from the tuyere close to the measurement point is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of blowing combustible dust into a waste melting furnace for thermally decomposing and melting waste such as general waste and industrial waste.

[0002]

2. Description of the Related Art As a method of treating general waste and industrial waste, waste is charged into a shaft furnace type waste melting furnace, and the waste is dried, preheated, pyrolyzed, burned, and melted. And
There is known a thermal decomposition / melting method for extracting slag or metal.

FIG. 4 is an explanatory view of a waste melting facility provided with a shaft furnace type waste melting furnace. In the waste melting furnace 1, waste, coke as a secondary material, and limestone are doubled from the furnace upper part. It is charged through the charging device 2 of the seal valve mechanism, and dried, thermally decomposed, burned, and melted. On the other hand, combustible components from the furnace are discharged from the duct 3 in the upper part of the furnace as pyrolysis gas,
After the combustion, the heat is used as heat and electric energy by auxiliary equipment such as the boiler 5 and the turbine generator. afterwards,
The exhaust gas is cooled by a gas cooler 6, passes through a dust collecting device 7, and is discharged from a chimney 9 by an induced blower 8.

[0004] At the lower part of the waste melting furnace, there are provided a plurality of blowing tuyeres 10 for blowing oxygen-enriched air in which air and oxygen are mixed, and ash is taken out from the slag port 11 as slag and metal. The oxygen-enriched air blown from the tuyere 10 burns coke in the furnace and char generated by pyrolysis,
The heat of combustion is used for drying, pyrolysis,
And used for melting incombustibles.

[0005] In the operation of the waste melting furnace, the combustible components in the charge are thermally decomposed at the lower portion in the waste melting furnace to generate dry distillation residues. The generated residue is burned by the air sent from the tuyere or deposited in the furnace.
Fines are scattered as combustible dust from the furnace in the air stream without being burned by the air sent from the tuyere. The combustible dust scattered from the furnace top is collected and blown into the furnace again through a tuyere provided in the furnace main body, which has the effect of reducing the coke ratio.

[0006] The applicant of the present application has filed a method of blowing fuel from a tuyere into a coke bed in Japanese Patent Application No. 11-217997 as a technique for treating flammable dust that has been scattered. What is blown from the tuyere is not limited to collected dust, but is used as general fuel.) This method
As shown in FIG. 4, coke wastes into a waste melting furnace,
When charged with limestone and dried, pyrolyzed, burned, melted and discharged, fuel is blown into the coke bed together with oxygen-enriched air at normal temperature or high-temperature air from the blast tuyere of the waste melting furnace into the coke bed. In the method, the top gas temperature of the waste melting furnace is detected, and when the top gas temperature exceeds a set value, the fuel injection amount is controlled so that the top gas temperature falls within a predetermined top gas temperature range. Or CO concentration (%) and CO ₂ concentration (%) in the top gas of waste melting furnace
Is calculated to calculate ηCO = CO ₂ / (CO ₂ + CO), and when the calculated ηCO exceeds a set value, the fuel injection amount is controlled so as to fall within a predetermined range.

[0007] In the case of processing various kinds of refuse having large fluctuations such as high-moisture refuse and irregular refuse, as well as general municipal refuse, the refuse falls to the furnace bottom without completing thermal decomposition of the refuse. There is. The combustible dust blown into the coke bed packed bed is appropriately mixed in the coke bed packed bed, and the blown combustible dust and coke are preferentially blown through the tuyere by oxygen-enriched air or hot air. The excess oxygen burns the incompletely pyrolyzed refuse directly in front of the tuyere. When the pyrolysis-incomplete refuse is directly burned, a space portion is generated due to a large volume reduction, a difference in ventilation resistance in a cross-sectional direction is generated, and the heat exchange efficiency may decrease.

The object of the invention of this application is to eliminate this space portion at an early stage. As means for this purpose, the temperature of the furnace top gas, the concentration of CO and CO ₂ in the furnace top gas are measured,
The occurrence of the space is known from this value, and the space is eliminated by controlling the fuel from the tuyere of the shaft furnace based on the information. However, the difference in the ventilation resistance in the cross-sectional direction of the dry distillation residue (space) is as follows.
Generally, it is likely to occur before the tuyere even in a furnace. However, as described above, since it is based on the information (temperature and concentration) of the top gas, there is a distance gap from the generation point, so that the discovery of the space is delayed, and the temperature of the top gas is Since the average temperature of each part is used, it is not possible to specify at which part in the cross-sectional direction the space part is generated. Therefore, there is a problem that it takes time to eliminate the phenomenon. Further, since it is necessary to blow dust in a direction where there is no space, a large amount of combustible dust stock is required, and a large hopper is required.

Accordingly, the present invention is to directly measure the temperature in the vicinity of a portion where a difference in airflow resistance in the cross-sectional direction of the dry distillation residue is likely to occur, to identify the generation location at an early stage, and to detect the flammable dust near the generation location. By controlling (increasing) the amount of air blown, the difference in gas flow resistance in the cross-sectional direction of the dry distillation residue is not eliminated as soon as possible.

[0010]

According to the present invention, a method for injecting combustible dust into a waste melting furnace comprises charging waste together with coke and limestone into a waste melting furnace, drying, pyrolyzing, burning and melting. Combustible dust scattered from the top of the waste melting furnace and collect the combustible dust from the blast tuyere of the waste melting furnace to the coke bed at room temperature. Alternatively, in the method of blowing together with high-temperature air, the furnace is disposed above the tuyere of the waste melting furnace at which the combustible dust is blown, and is disposed at intervals in the cross-sectional direction of the furnace body filled with the object to be treated. The temperature in the furnace is measured with a plurality of thermometers, and when the measured temperature is equal to or higher than a preset temperature, the amount of combustible dust blown from the tuyere close to the measurement point is controlled. It is characterized by the following.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 (a) shows a main part of equipment for carrying out a method for injecting dust in a waste melting furnace according to the present invention, and FIG. 1 (b) explains control of the injecting method. FIG. The same components as those of the conventional waste melting facility shown in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 15 denotes a dust remover that collects dust scattered from the furnace top, and 16 denotes a blowing device that blows the collected dust through the tuyere 10.

As described above, as an object to be melted,
When treating not only general municipal waste but also various refuse with large fluctuations, such as high-moisture refuse and deformed refuse, the refuse may fall to the furnace bottom without being completely pyrolyzed. The combustible dust blown into the coke bed packed bed is appropriately mixed in the coke bed packed bed, and the blown combustible dust and coke are preferentially blown through the tuyere by oxygen-enriched air or hot air. Reacts with and burns,
Excess oxygen burns the incompletely pyrolyzed waste directly in front of the tuyere. When the incompletely pyrolyzed refuse is directly burned, a space portion is generated due to a large volume reduction, a difference in ventilation resistance occurs in a cross-sectional direction, and the heat exchange efficiency may be reduced. Therefore,
The temperature measurement point for specifying the difference (space portion) of the ventilation resistance needs to be at least above the tuyere that blows combustible dust, and is preferably as close as possible to the tuyere that blows combustible dust. If the temperature in the packed bed of the object to be treated can be measured, the occurrence of the space can be easily grasped.

In FIG. 1 (a), it is above the tuyere of the waste melting furnace 1 for blowing combustible dust, and
A plurality of thermometers 12 are installed at intervals in the direction of the cross section of the furnace that is filled with the workpiece. If a difference in ventilation resistance (space part) occurs in the carbonization residue, the heat exchange efficiency in that part decreases, and the gas temperature rises. Therefore, the space generated from the installation place of the thermometer 12 that measures the risen temperature. The part can be specified.

The measurement signal of each thermometer 12 is input to a space specifying operation unit 13 for specifying a space, and it is determined whether or not the temperature measured by each thermometer is higher than a preset temperature. From the result, the occurrence and location of the space part are specified.

Information on the location and temperature at which the space is generated from the space specifying operation unit 13 is input to the combustible dust blowing amount calculation unit 14 to identify the tuyere to be increased, and to blow the combustible dust to the tuyere. The inset amount is calculated.

The signal of the operation result is supplied to a flow controller (FIC) provided in the combustible dust blowing device of the specified tuyere.
And the amount of combustible dust blown into the tuyere is adjusted. FIG. 2 is a graph showing an example of injectable combustible dust of the present invention and a temperature change in a shaft part furnace.

As shown in the figure, four thermometers (12-
1, 12-2, 12-3, 12-4). That is, there are four measurement points (a), (b), (c), and (d).

In the figure, up to the time x,
The blowing amount of the combustible dust is constant at 100 kg for each tuyere, and shows a state in which the blowing amount control (increase) corresponding to the set temperature has been performed after time x.

By the way, in this figure, (c) (12)
Looking at the temperature change at the position of -3), a sharp temperature rise is observed at the beginning, but it is determined that a space portion is generated near this portion and the heat exchange efficiency is reduced. However, as can be seen from this example, there is a case where the space is naturally resolved with the passage of time. However, in general, the space remains for a long period of time, resulting in a decrease in slag temperature and a decrease in the amount of waste disposal.

Therefore, in the present invention,
Comprehend the correlation between the space formed and the furnace temperature, and assume the temperature range where the space starts to be formed from this temperature process (setting)
The amount of dust blown when the temperature reaches the set temperature range is increased.

The set temperature must be empirically determined based on the positional relationship of the shaft thermometer in the height direction and the like. In this embodiment, the set temperature is 400 ° C.

In FIG. 2, (c) (12-
In the temperature of 3), since the measured temperature in the furnace exceeded the set temperature of 400 ° C. after 8:00 of the elapse of time, it was determined that a space portion was generated in the dry distillation residue in the vicinity, and the blade located in the vicinity was determined. By controlling (increasing) the amount of flammable dust blown from the mouth, the temperature of the portion does not rise thereafter,
After changing around 0 ° C., the temperature dropped to a temperature of about 300 ° C.

FIG. 3 compares the measurement result of the furnace top gas temperature with the measurement result of the gas temperature in the shaft portion.

As described above, conventionally, the generation of the space was grasped while observing the change in the furnace gas temperature, and the amount of flammable dust blown from all tuyeres was increased. The generation of the space is grasped from the change in the gas temperature in the section, and only the amount of flammable dust blown from the tuyere in the vicinity is to be increased, but as shown in the figure, the furnace top gas temperature is Although it shows an extremely gradual change because it has been averaged for each part in the furnace, as in the present invention, the temperature history measured inside the shaft part reacts sensitively like an elbow, The timing of the temperature rise is also early. This means that the present invention makes it possible to know the beginning of the space portion sooner and to know it more clearly.

[0025]

According to the present invention, the gas temperature is measured at a plurality of locations from the vicinity of the tuyere where the difference in air flow resistance (space portion) in the cross-sectional direction of the dry distillation residue is likely to occur, and in the material-filled layer above the tuyere. By doing so, it is possible to quickly and clearly grasp the occurrence of the space, and to eliminate the occurrence of the space early by increasing the amount of combustible dust blown into the vicinity of the occurrence You can do it. As a result, stable operation can always be maintained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of equipment for implementing a method of the present invention.

FIG. 2 is a graph showing an example of flammable dust injection according to the present invention.

FIG. 3 is a graph showing temperature measurement results of the present invention and a comparative example.

FIG. 4 is an explanatory view of a waste melting facility provided with a shaft furnace type waste melting furnace.

[Explanation of symbols]

1: Waste melting furnace 2: Charging device 3: Duct
4: Combustion chamber 5: Boiler 6: Gas cooler 7: Dust collector 8: Induction blower 9: Chimney 10: Blower tuyere 11: Slag outlet 12:
Thermometer 13: Space part specific calculation part 14: Combustible dust blowing amount calculation part 15: Dust remover 16: Blowing device

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F27B 1/28 F27D 19/00 A F27D 19/00 B09B 3/00 303K (72) Inventor Hideharu Shibaike Tobata-ku, Kitakyushu Nakahara 46-59 Nippon Steel Corporation Engineering Business Headquarters (72) Inventor Yoshiharu Ueno 14-1 Higashinonomiyacho, Ibaraki City, Osaka Prefecture Ibaraki City Environmental Sanitation Center (72) Inventor Ryohei Kosaka Higashinonomiyamachi, Ibaraki City, Osaka Prefecture No. 14-1 Ibaraki City Environmental Health Center (72) Inventor Yoshinobu Nishida 14-1 Higashinonomiyamachi, Ibaraki City, Osaka Prefecture F-term in Ibaraki City Environmental Health Center 3K061 AA16 AB02 AB03 AC01 BA04 CA07 DB16 3K062 AA16 AB02 AB03 AC01 BA02 CA01 CB04 DA01 DA32 DB01 4D004 AA46 BA03 CA24 CA29 CA42 CB04 CC02 CC11 DA01 DA02 DA06 DA10 4K045 AA01 BA10 DA02 DA04 GB11 NA01 4K056 BB01 CA20 FA03 FA13

Claims (1)

[Claims] When the waste is charged together with coke and limestone into a waste melting furnace, and dried, thermally decomposed, burned, melted and discharged, combustible dust scattered from the top of the waste melting furnace is discharged. In the method in which combustible dust is collected and collected and blown into the coke bed together with the oxygen-enriched air at room temperature or high-temperature air through the tuyere of the waste melting furnace, Is also at the top, and the temperature in the furnace is measured with a plurality of thermometers installed at intervals in the cross-sectional direction of the furnace body filled with the object to be processed, and the measured temperature is determined in advance. A method for injecting combustible dust into a waste melting furnace, comprising controlling an amount of combustible dust to be blown from a tuyere close to the measurement point when the temperature reaches or exceeds a set temperature.