JP2000000430A - Dioxins suppressing method, treatment of waste gas and treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dioxins suppressing method, treatment of waste gas and treating device by which the reproduction of dioxins contained in waste gas discharged from various incinerators such as a city refuse incinerator, an industrial waste incinerator and a sludge incinerator and a melting furnace. SOLUTION: Four chemical injection nozzles 14a to 14d are vertically arranged two by two in a gas treating device 14, a chemical 15 (N,N- diethylaminoethanol) corroding the active metal contained in the porous fly ash in a waste gas is sprayed into the gas treating device 14 as the film to corrode the metal contained in the fly ash in the waste gas, the reproduction of dioxins is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an incinerator for municipal waste,
Dioxin control method and exhaust gas treatment that suppresses regeneration of dioxins contained in exhaust gas discharged from various types of incinerators such as industrial waste incinerators, sludge incinerators, pyrolysis furnaces, gasifiers, and melting furnaces The present invention relates to a method and a processing device.

[0002]

2. Description of the Related Art The flow of a conventional refuse incinerator is shown in FIG. As shown in FIG.
When incinerating the refuse, the refuse 01 is put into the incinerator 02, and the moisture is evaporated and dried by radiant heat or the like in the incinerator 02, and the volatile component is pyrolyzed to gas. The combustible gas and the fixed carbon come into contact with oxygen in the primary air 03 and burn in the high temperature incinerator 02. The combustion residue 04 is discharged from the furnace bottom to the outside of the furnace. The gaseous unburned portion in the combustion area in the incinerator 02 comes into contact with oxygen in the secondary air 05 and immediately burns completely. After the exhaust gas 06 generated in the incinerator 02 is cooled by the exhaust gas cooling device 07, the fly ash 09 is removed by an exhaust gas treatment device (eg, a bag filter) 08 and discharged from the chimney 010. The fly ash is converted into slag in the fly ash melting furnace 011 and discharged as slag 012.

[0003] The fly ash that has flew out in the combustion area in the incinerator 02 is porous, and unburned liquid tar and unburned solid particles adhere to the surface. These surface adhering substances form condensation polymers such as hydrocarbons in a high-temperature combustion zone, and form a porous heat insulating layer. This heat insulation layer has a problem that it prevents complete combustion of unburned substances in the porous fly ash. A similar problem occurs when unburned substances enter the porous portion of the porous fly ash. The unburned substances in the fly ash include toxic dioxins and their precursors. Dioxins are thermally decomposed at high temperatures in an incinerator, and as shown in FIG. 6, even when exhaust gas 06 enters the exhaust gas cooling device 07, it is decomposed in the thermal decomposition / combustion region of dioxins at 400 ° C. or higher. However, the low temperature range of 400 ° C or lower of the exhaust gas cooling device (400 to 150 ° C)
In this case, dioxins may be regenerated, which is a problem.

Here, the dioxins are a general term for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).
It is said that a small amount is generated when a chlorine compound and a certain kind of organic chlorine compound are burned, and it is a chemically colorless crystal at normal temperature. There are from monochloride to octachloride depending on the number of chlorine,
There are 75 isomers of PCDDs and 135 isomers of PCDFs, and among them, dibenzo-p-
Dioxins (T ₄ CDDs) are known to be the most toxic. In addition, as harmful chlorinated aromatic compounds, in addition to dioxins, various organic chlorine compounds (for example, aromatic compounds such as phenol and benzene (for example, chlorobenzenes, chlorophenol and chlorotoluene) ), Chlorinated alkyl compounds, etc.) must be removed from the exhaust gas, and in the exhaust gas treatment, the regeneration of dioxins must be suppressed.

The following Table 1 shows an example of the components of fly ash.

[Table 1]

[0006] As shown in Table 1, C is contained in fly ash.
u, Fe, etc., in a high-temperature gas, due to the catalytic action of these active metals, in the above-mentioned temperature range, a dioxin precursor is converted into Cu
The dioxins are regenerated as a catalyst.

[0007]

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In view of the above problems, the present invention provides a method for controlling dioxins, which suppresses regeneration of trace amounts of dioxins contained in exhaust gas from precursors in exhaust gas treatment.
An object of the present invention is to provide an exhaust gas treatment method and a treatment apparatus.

[0009]

Means for Solving the Problems The invention of claim 1 which solves the above problems is characterized in that active metals contained in porous fly ash in exhaust gas are corroded, and regeneration of dioxins is suppressed. And

[0010] The invention of claim 2 is characterized in that, in claim 1, the substance that corrodes the active metal contained in the porous fly ash in the exhaust gas is N, N-diethylaminoethanol.

The invention of claim 3 is characterized in that, in claim 1 or 2, the corrosion of the active metal contained in the porous fly ash in the exhaust gas is performed in a region higher than the regeneration temperature of dioxins. I do.

[0014] The invention of claim 4 is a method for treating harmful substances in exhaust gas, which corrodes active metals contained in porous fly ash in exhaust gas and regenerates dioxins in exhaust gas. It is characterized by suppression.

[0013] The invention of claim 5 is a device for treating harmful substances in exhaust gas, wherein a gas cooling device for cooling exhaust gas discharged from an incinerator corrodes active metals contained in porous fly ash. A means for introducing a substance to be added.

According to a sixth aspect of the present invention, in the fifth aspect, the material for forming the corrosion film is charged into a film form, and the material is brought into contact with the porous fly ash in a temperature range of 400 ° C. or more after the charging. And

The invention of claim 7 is the exhaust gas treatment device according to claim 5 or 6, wherein an exhaust gas treatment device is provided on the downstream side of the gas cooling device.

The invention of claim 8 is characterized in that, in claim 7, the exhaust gas treatment device is provided with catalyst means for decomposing harmful substances.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

FIGS. 1 to 3 show an example of an exhaust gas treatment apparatus for implementing the method for controlling dioxins of the present invention.

FIG. 1 is a schematic diagram of an exhaust gas treatment apparatus according to the first embodiment. As shown in FIG. 1, an exhaust gas treatment apparatus according to the present embodiment is used for municipal waste, industrial waste,
A gas cooling device 14 for cooling exhaust gas 13 discharged from various incinerators 12 for incinerating various refuse 11 such as sludge, and a chemical for forming a corrosion film on the surface of porous fly ash in the exhaust gas in the gas cooling device 14 The system is composed of a medicine introduction means for introducing the gas, a flue gas treatment device (for example, a bag filter) for removing dust and the like in the flue gas 13 and a chimney 17 for discharging flue gas from which fly ash has been removed to the outside. .

FIG. 2 is a schematic diagram of an exhaust gas treatment apparatus according to a second embodiment. Further, in the exhaust gas treatment apparatus shown in FIG. 2, a pyrolysis furnace 21 for thermally decomposing the refuse 11, a melting furnace 22 for melting the ash, a gas cooling device 14 for cooling the exhaust gas 13 from the melting furnace 22, A chemical introduction means for introducing a chemical 15 for forming a corrosion film on the surface of the porous fly ash in the exhaust gas 13 into the cooling device 14, and an exhaust gas treatment device (for example, a bag filter or the like) for removing fly ash, dust and the like in the exhaust gas ) 16 and a chimney 17 for discharging exhaust gas from which fly ash has been removed to the outside.

FIG. 3 is a schematic diagram of an exhaust gas treatment apparatus according to the third embodiment. Further, in the exhaust gas treatment apparatus shown in FIG. 3, a pyrolysis furnace 31 for pyrolyzing the refuse 11, a combustion furnace 32 for burning pyrolysis products from the pyrolysis furnace 31, and an ash from the combustion furnace 32 are melted. A melting furnace 33, a gas cooling device 14 for cooling the exhaust gas 13 from the melting furnace 33, and a chemical injection for charging a chemical 15 for forming a corrosion film on the surface of the porous fly ash in the exhaust gas 13 into the gas cooling device 14. It is composed of a means, an exhaust gas treatment device (for example, a bag filter or the like) 16 for removing dust and the like in the exhaust gas, and a chimney 17 for discharging the exhaust gas from which fly ash has been removed to the outside.

If necessary, the treatment apparatus may further include an exhaust gas treatment catalyst (titanium, vanadium, tungsten, a mixture of two or more of these metal elements, and a mixture of two or more of these metal elements) for decomposing dioxins. Catalyst containing at least one selected from the group consisting of solid solution oxides: in particular, a catalyst having a specific surface area of 100 m ² / g or more)
Alternatively, a catalyst device having a similar exhaust gas treatment catalyst for decomposing dioxins and introducing ammonia to remove NOx and the like may be provided on the downstream side of the exhaust gas treatment device 16.

A gas cooling device 1 for cooling the exhaust gas 13
FIG. 4 shows the details of the chemical feeding means for feeding the chemical 15 for forming a corrosion film on the surface of the porous fly ash provided in FIG. FIG.
As shown in (1), the gas cooling device 14 is provided with two drug injection nozzles 14a to 14d at upper and lower portions, respectively, and sprays the drug 15 into the gas processing device 14 in a film form. Further, nozzles may be provided in two or three stages in the method of traveling the exhaust gas 13. In addition, as long as it can be sprayed in the form of a film by means other than the nozzle, the means for injecting the drug of the present invention is not limited to the nozzle, and the arrangement and number of the nozzles depend on the shape and the shape of the gas cooling device 14. What is necessary is just to change suitably according to a volume.

The chemical 15 is atomized to form a gas cooling device 1
The reason why the film is sprayed into the film 4 is as follows. When the chemical 15 is sprayed in the form of a film, the chemical adsorbs to the porous fly ash contained in the exhaust gas 1 passing through the gas cooling device 14. The agent rapidly corrodes the surface of an active metal such as Cu in a high-temperature gas, and covers the porous fly ash surface with a corrosion film. In addition, the above-mentioned drug enters the porous portion and acts on the active metal which has already entered the porous portion. The active metal in the cover fly ash is corroded by the corrosion film, and the activity of the porous fly ash as a catalyst is reduced. In addition, when acting on the active metal that has entered the porous portion, when corrosion of the active metal occurs, a corrosive substance precipitates on the surface of the porous fly ash to form a film on the surface of the fly ash, and the film forms Catalyst activity decreases. As described above, when the porous fly ash having reduced activity as a catalyst enters a region of 400 ° C. or less, which is an exhaust gas cooling region, gaseous dioxins and precursors thereof become liquid or solid, Although deposited on the surface of the porous fly ash, since the surface activity of the porous fly ash is reduced, dioxins are not further generated on the surface of the porous fly ash, and its concentration increases. No more.

Preferred conditions of the atmosphere in the gas cooling device 14 for injecting the medicine are as follows. The temperature range of the gas cooling device 14 is set to 400 ° C. or higher, which is a temperature higher than the regeneration temperature of dioxins,
preferable. This is because if the temperature is lower than 400 ° C., regeneration of dioxins is started before the active metal is corroded. The required gas residence time after injection of the drug 15 is preferably 5 seconds or more, more preferably 5 to 10 seconds, in a temperature range of 400 ° C. or more. This is 5
If the time is less than seconds, good coating or the like is not performed. The concentration of the porous fly ash in the gas is preferably 1 g / m ³ N or more, to which the fine drug droplets are adsorbed. This is because, if it is less than 1 g / m ³ N, the probability that the drug droplets will be adsorbed on fly ash will decrease, and the vaporization and burning will occur before the droplets are adsorbed on fly ash. This is because it will decrease. It is preferable that the actual gas velocity at which the fine porous fly ash floats is 1 m / sec or less. This is 1m
If it exceeds / sec, the particle diameter of the suspended particles increases, making it difficult for the drug to reach the active metal present inside the particles,
This is because it becomes difficult to corrode even the active metal at the particle center.

The injection form of the medicine 15 and the conditions of the injection area are shown below. The form before the injection of the drug is preferably a liquid or a slurry. This is for injecting into the gas cooling device 14 in a good film spray state. As shown in FIG. 4 described above, the injection of the chemical is preferably performed by spraying in a film shape (a so-called flat pattern spray) using a nozzle so as to be orthogonal to the gas flow direction. This is because when not sprayed in the form of a film, it does not adhere well to fly ash in the exhaust gas floating over the entire area in the gas cooling device,
This is because the film cannot be coated. It is preferable that the particle size of the spray injected with the nozzle through the nozzle is such that the particle size adsorbed on fly ash is 100 μm or less. This is because when the particle size exceeds 100 μm, good coating cannot be performed or the fly ash cannot penetrate into the porous portion. It is preferable that the injection amount of the chemical is 10% by weight or less based on the fly ash amount. This is because even if added in excess of 10% by weight, no further effect is exhibited.

The conditions of the chemical 15 for forming a corrosion film on the surface of the porous fly ash of the present invention are shown below. Must be soluble in water and have a specific gravity of 0.8 or more. Low odor, not volatile or explosive. Viscosity is 3cP or less (20 ° C) and boiling point is 200 ° C
Must be: Low heat of dissolution in water. Many N groups. Corrosion of active metals such as copper and iron. Examples of the agent that forms a corrosion film on the surface of the porous fly ash that satisfies the above conditions include N, N-diethylaminoethanol, but the present invention is not limited to this, and the present invention is not limited thereto. Any material may be used as long as it has a function of corroding the contained active metal.

In the following, catalytic corrosion using N, N-diethylaminoethanol (active metals such as Cu catalysts are corroded; Cl is eliminated from compounds having chlorine groups).
Is shown in “Formula 2”.

[0029]

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The above N, N-diethylaminoethanol
Other drugs include, for example, monoethanolamine (H_Two
NCH_TwoCH_TwoOH), triethanolamine (CH_Two
CH _TwoOH)_ThreeN, triethylamine (C_TwoH_Five)_ThreeN
Etc. can be exemplified.

Table 2 below shows properties and physical properties of N, N-diethylaminoethanol.

[Table 2]

Table 3 below shows the results of dioxin reduction tests using the above N, N-diethylaminoethanol. In the table, when dioxins (O ₂ 12% conversion value) were measured at the inlet of the exhaust gas treatment apparatus, the result was 190 ng-TEQ / m ³ N before the injection of the drug, but 99 ng-TEQ / m ³ N after the injection of the drug. m ³ N, and the reduction rate was as good as 48%. In addition, dioxins (O ₂ 12) in the collected ash collected by the exhaust gas treatment device
% Conversion value), 5.7n before drug injection
What was g-TEQ / g was 3.0 g after injecting the drug.
ng-TEQ / g, which was as good as the reduction rate of 47%.

[0033]

[Table 3]

[0034]

As described above, according to the first aspect of the present invention, the active metal contained in the porous fly ash in the exhaust gas is corroded and the regeneration of dioxins is suppressed. Further, it is sufficient to treat the exhaust gas without regeneration of dioxins, and the treatment of the exhaust gas becomes easy.

According to the second aspect of the present invention, in the first aspect, the substance which corrodes the active metal contained in the porous fly ash in the exhaust gas is N, N-diethylaminoethanol. The corrosion becomes good, and the suppression of dioxins is improved.

According to the third aspect of the present invention, according to the first or second aspect, the active metal contained in the porous fly ash in the exhaust gas is corroded in a region higher than the regeneration temperature of dioxins. The active metals in the fly ash can be corroded before the dioxins are regenerated.

According to a fourth aspect of the present invention, there is provided a method for treating harmful substances in exhaust gas, wherein active metals contained in porous fly ash in the exhaust gas are corroded to regenerate dioxins in the exhaust gas. Since the formation is suppressed, it is sufficient to treat the exhaust gas without regenerating dioxins, thereby facilitating the exhaust gas treatment.

According to the fifth aspect of the present invention, there is provided a device for treating harmful substances in exhaust gas, wherein the gas cooling device for cooling exhaust gas discharged from an incinerator is provided with an active metal contained in porous fly ash. Since a means for introducing a substance that corrodes is provided, dioxins are not regenerated more than before, and no burden is placed on subsequent exhaust gas treatment equipment, and exhaust gas treatment is facilitated.

According to a sixth aspect of the present invention, in accordance with the fifth aspect, the substance for forming the corrosion film is charged in a film form, and the dioxin comes into contact with the porous fly ash in a temperature range of 400 ° C. or more after the charging. The active metals in the fly ash can be corroded before the ash is regenerated, so that no burden is placed on the exhaust gas treatment equipment thereafter, and the exhaust gas treatment is facilitated.

According to the invention of claim 7, in claim 5 or 6, an exhaust gas treatment device is provided on the downstream side of the gas cooling device, so that fly ash can be removed and high efficiency exhaust gas treatment can be performed. It becomes possible.

According to the invention of claim 8, in claim 7, the exhaust gas treatment device is provided with a catalyst means for decomposing harmful substances, so that dioxins, nitrogen-containing compounds and the like can be further decomposed. Highly efficient exhaust gas treatment becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an exhaust gas treatment apparatus according to a first embodiment.

FIG. 2 is a schematic diagram of an exhaust gas treatment apparatus according to a second embodiment.

FIG. 3 is a schematic diagram of an exhaust gas treatment apparatus according to a third embodiment.

FIG. 4 is a detailed view of a gas cooling device provided with a chemical injection means for forming a corrosion film on the surface of porous fly ash.

FIG. 5 is a schematic diagram of an exhaust gas treatment apparatus according to the related art.

FIG. 6 is a detailed view of a gas cooling device according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Garbage 12 Incinerator 13 Exhaust gas 14 Gas cooling device 14a-14d Chemical injection nozzle 15 Chemical 16 Exhaust gas treatment device 17 Chimney 21 Thermal decomposition furnace 22 Melting furnace 31 Thermal decomposition furnace 32 Combustion furnace 33 Melting furnace

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23J 15/00 HF term (Reference) 3K070 DA01 DA02 DA06 DA07 DA12 DA14 DA25 DA32 DA40 DA48 DA58 DA77 4D002 AA21 AA28 AC04 BA03 BA12 BA13 BA14 CA01 CA13 DA32 EA02 GA01 GA02 GB01 GB02 GB03 GB06 HA10 4D048 AA11 AB03 AC03 BA07X BA23X BA27X BA41X BA42X CA03 CD01 CD03 CD08 DA02 DA03 DA05 DA06 DA10 DA20

Claims (8)

[Claims] 1. A method for controlling dioxins, which comprises corroding active metals contained in porous fly ash in exhaust gas to suppress regeneration of dioxins. 2. The method for controlling dioxins according to claim 1, wherein the substance that corrodes the active metal contained in the porous fly ash in the exhaust gas is N, N-diethylaminoethanol. 3. The method for controlling dioxins according to claim 1, wherein the corrosion of the active metal contained in the porous fly ash in the exhaust gas is performed in a region higher than a temperature at which the dioxins are regenerated. 4. A method for treating harmful substances in exhaust gas, wherein the active metal contained in the porous fly ash in the exhaust gas is corroded,
An exhaust gas treatment method comprising suppressing regeneration of dioxins in exhaust gas. 5. An apparatus for treating harmful substances in exhaust gas, comprising means for charging a substance that corrodes active metals contained in porous fly ash into a gas cooling apparatus that cools exhaust gas discharged from an incinerator. An exhaust gas treatment device characterized by being provided. 6. The exhaust gas treatment apparatus according to claim 5, wherein the substance for forming the corrosion film is charged in a film form, and is contacted with the porous fly ash in a temperature range of 400 ° C. or more after the charging. 7. The exhaust gas treatment device according to claim 5, wherein an exhaust gas treatment device is provided downstream of the gas cooling device. 8. The exhaust gas treatment device according to claim 7, wherein the exhaust gas treatment device is provided with catalyst means for decomposing and processing harmful substances.