JPH119960A - Material for preventing emission of dioxin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive not to need a separate treatment of activated carbon discharged out of a dust collecting facility by impregnating an emissionpreventing material with activated carbon bearing an amine compound. SOLUTION: As an amine compound to be used for this material, one or two types of alkyl amines and alkanol amines may be employed and especially alkanol amines are preferable since the amines have high dioxin decomposing reactivity. The preferable amount of those amine compounds to be deposited is 0.1-10 wt.% to the amount of activated carbon, especially preferably 1-7 wt.%. The treatment apparatus mainly comprises a combustion furnace main body 1, an electric dust collector 2, and a scrubber 3 and substances 4 thrown to the combustion furnace main body 1 are fired and a combustion gas 5 is sent to a dust collecting process through a chimney 7. Bottom ash 6 is discharged out of the combustion furnace main body 1. The combustion gas is discharged outside air out of the chimney 9 after being passed further through the scrubber 3. The material for preventing emission is added one or a plurality of points somewhere between the point B and the point E illustrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dioxin emission preventive material for reducing the amount of dioxins released into the atmosphere due to exhaust gas from an incinerator.

[0002]

BACKGROUND OF THE INVENTION In incinerators such as refuse incinerators, during combustion, organic compounds such as phenol, benzene and acetylene, chlorinated aromatic compounds such as chlorophenol and chlorobenzene, and dioxin precursors such as chlorinated alkyl compounds. Occurs. When the fly ash coexists, these dioxin precursors become dioxins by the reaction shown in the following formula by the catalytic action, and are present in the exhaust gas. (In the present invention, the dioxin and the dioxin precursor are combined together. Dioxins ").

[0003]

Embedded image

[0004] The dioxin formation reaction is carried out at 40
It hardly occurs at a high temperature of 0 ° C. or higher, and occurs when the temperature is reduced to around 200 to 400 ° C.

That is, Karasek (Science 237: 754, 1987),
Stieglitz (Chemosphere 18: 1219,1989), Hutzinger
(Chemosphere 14: 581, 1985) indicate that the production of dioxins in incinerators is mainly due to the conversion of dioxin precursors contained in exhaust gas to dioxins by the catalytic action of fly ash. The optimum temperature for this reaction is around 300 ° C. When the dioxin precursor such as chlorophenol or chlorobenzene is adsorbed on the dioxin-forming catalytically active site of the fly ash particles and is exposed to a temperature condition of 200 to 400 ° C., the dioxin precursor is catalyzed by the fly ash. Reacts to produce dioxin.

Conventionally, as a method for removing these dioxins contained in exhaust gas, in the exhaust gas treatment process of a refuse incinerator, powdery activated carbon is injected before a dust collector, before a spray absorber, before a scrubber, or the like to remove dioxin. Method of adsorption ("Organohalogen Compounds" 27:17
7-182 (1996)).

[0007]

The ordinary activated carbon generally adsorbs and removes dioxins in exhaust gas almost effectively.
Activated carbon adsorbed with dioxins is collected in the dust collector together with fly ash, so that the concentration of dioxin in the collected ash increases and a separate activated carbon disposal method is required.

Further, activated carbon has a catalytic activity for producing dioxin from a dioxin precursor such as chlorobenzene and chlorophenol, similar to fly ash. For this reason, when the temperature in a dust collecting facility such as a bag filter or an electric dust collector is 200 ° C. or higher, a large amount of dioxin is generated by a catalytic reaction from activated carbon adsorbing a dioxin precursor. Furthermore, dioxin was also generated by the catalytic reaction of the coexisting fly ash.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a dioxin emission preventing material capable of reducing the concentration of dioxin in a gas released into the atmosphere. Another object of the present invention is to provide a dioxin emission preventive material capable of preventing the generation of dioxins in dust collection equipment.

A further object of the present invention is to provide a dioxin emission preventing material which does not require separate treatment of activated carbon discharged from a dust collecting facility.

[0011]

The dioxin emission preventing material of the present invention is characterized in that it contains activated carbon carrying an amine compound (hereinafter sometimes referred to as "amine-loaded activated carbon").

When the dioxin emission preventive material of the present invention is injected into exhaust gas from an incinerator or the like, the dioxin in the exhaust gas is adsorbed on the amine-supporting activated carbon of the emission preventive material and reacts with the amine compound to decompose. Further, the dioxin precursor is also adsorbed on the activated carbon together with the dioxin. However, since the amine compound carried on the activated carbon has an action of suppressing the dioxin generation reaction, the generation of new dioxin is suppressed.

The amine-carrying activated carbon added to the exhaust gas is collected by a dust-collecting facility. If the gas temperature in the dust-collecting facility is 200 ° C. or higher, preferably 220 ° C. or higher, the amine-carrying activated carbon is adsorbed on the amine-carrying activated carbon. The reaction (decomposition reaction) between the dioxin and the amine compound is accelerated.

[0014]

Embodiments of the present invention will be described below in detail.

In the present invention, the activated carbon has a particle size of several mm to 20 μm in view of its handleability and adsorption efficiency.
It is preferable to use those having a degree.

As the amine compound, one or two or more of alkylamines such as trimethylamine and alkanolamines such as triethanolamine and monoethanolamine can be used. In particular, alkanolamines have high dioxin decomposition reactivity. It is suitable.

The preferred loading of these amine compounds is from 0.1 to 10% by weight, particularly preferably from 1 to 7% by weight, based on the activated carbon.

For supporting the amine compound on activated carbon,
Activated carbon may be immersed in a solution in which an amine compound is dissolved in water or an organic solvent such as methanol or ethanol, and impregnated with the amine compound solution, and then the solvent may be evaporated under heating or reduced pressure. In this case, the concentration of the amine compound solution is appropriately determined depending on the amount of the amine compound to be supported on the activated carbon. It is preferable to use an amine compound solution having a moderate concentration.

This activated carbon carrying amine is preferably added to the exhaust gas stream in the form of particles or powder. In the case of incineration equipment, it is preferable that the amine-carrying activated carbon is added, for example, in an exhaust gas flue from an incinerator to a dust collector. The location of addition of the amine-carrying activated carbon in the flue is not particularly limited as long as it is before the dust collector, but in order to increase the contact time between the exhaust gas and the amine-carrying activated carbon, it is preferable that the addition be performed on the upstream side as much as possible. preferable. However,
In order to prevent the combustion of activated carbon, it is preferable to add the emission preventive material of the present invention to a gas having an exhaust gas temperature of 500 ° C. or lower.

In the case of incinerator exhaust gas, the injection amount of amine-supported activated carbon is about 10 to 500 mg, more preferably 50 to 150 mg, per 1 Nm ^{3 of} exhaust gas.

The addition site of the dioxin emission preventing material of the present invention is not limited to one site, but may be a plurality of sites.

After the emission preventing material is added to the exhaust gas, the exhaust gas is subjected to dust collection processing by a dust collecting facility such as an electric dust collector or a bag filter. At this time, if the temperature of the dust collector is 200 ° C. or higher, a large amount of dioxin is generated by the catalytic action of activated carbon or fly ash in the conventional method, but in this method, the decomposition of dioxin or its precursor adsorbed and collected on the activated carbon is performed. As the reaction occurs, part of the amine compound supported on the activated carbon volatilizes,
It acts on fly ash present in the surroundings and also suppresses the dioxin production reaction due to fly ash.

Next, an example in which a release preventing material is added in a normal exhaust gas treatment step will be described with reference to FIG.

The processing apparatus shown in FIG. 1 is mainly composed of an incinerator main body 1, an electric dust collector 2 and a scrubber 3, in which the input material 4 burns in the incinerator main body 1, and the exhaust gas 5 passes through a flue 7 for dust collection. Sent to the process. Bottom ash 6 from incinerator body 1
Is discharged. The collected fly ash 8 is discharged from the electric dust collector 2. The exhaust gas is further discharged from the chimney 9 through the scrubber 3 to the atmosphere.

The release-preventing material of the present invention is added, for example, at any one or a plurality of points between points B to E in the drawing.

The emission preventive material of the present invention can be added not only to an electric dust collector but also to a combustion facility provided with various dust collecting facilities such as a bag filter. When the temperature inside the dust collecting facility is set to 200 ° C. or more, particularly 220 ° C. or more, dioxin adsorbed on the amine-supported activated carbon can be decomposed by reaction with the amine compound supported on the activated carbon.

The dioxin release inhibitor of the present invention comprises:
In addition to various municipal waste incinerators, it can be applied to various types of exhaust gas from industrial waste incinerators, medical waste incinerators, incineration ash melting furnaces, RDF furnaces, and the like. In addition, furnace types such as stoker furnace, rotary kiln, fluidized bed furnace, continuous furnace, quasi-continuous furnace,
It can be applied to the treatment of exhaust gas from various furnaces regardless of the type of furnace such as a batch furnace.

[0028]

EXAMPLES The effects of the present invention will be described below with reference to examples and comparative examples.

[0029] Example 1 stoker, in a laboratory incinerator consisting of a waste heat boiler and bag filter is incinerated municipal waste, the amine-carrying activated carbon to the exhaust gas at a rate of 100mg to exhaust gas 1 Nm ^3, before the bag filter The exhaust gas was injected at a temperature of about 300 ° C., and the dioxin concentration was measured by the following measurement method. The amount of waste incinerated is 150 t / 24 hr, the exhaust gas flow rate is about 40,000 Nm ³ / hr, the concentration of dust in the exhaust gas flowing into the bag filter is 2.0 g / Nm ³ , and the average gas temperature in the bag filter is 220 ° C. Met. In the bag filter, dust collected on the filter was removed at intervals of once every four hours.

The amine-carrying activated carbon used was a mixture of activated carbon made of peat having an average particle diameter of 20 μm and a 5% by weight aqueous solution of triethanolamine at a weight ratio of 1: 1 and thoroughly stirred. Was prepared. The amount of triethanolamine supported by the amine-supported activated carbon was 5% by weight.

Measurement of Dioxin Concentration Samples were collected and analyzed in accordance with the “Manual for Analysis of Dioxins” of the Waste Research Foundation. The samples for dioxin analysis were two points: exhaust gas at the outlet of the bag filter and dust ash.

The results are shown in Table 1. Table 1 shows the dioxin concentration when no amine-supported activated carbon was added as a blank.

Comparative Example 1 The dioxin concentration was measured in the same manner as in Example 1 except that activated carbon not carrying triethanolamine was injected, and the results are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that 5% by weight
Dioxin concentration was measured in the same manner except that monoethanolamine-supported activated carbon was used, and the results are shown in Table 1.

Example 3 The procedure of Example 1 was repeated except that the amine-supported activated carbon was 5% by weight.
The dioxin concentration was measured in the same manner except that trimethylamine-supported activated carbon was used, and the results are shown in Table 1.

[0036]

[Table 1]

From Table 1, it can be seen that the amine-supported activated carbon can reduce both the dioxin concentration in the exhaust gas and the dioxin concentration in the dust ash.

[0038]

As described above in detail, according to the dioxin emission preventive material of the present invention, dioxin in exhaust gas is efficiently adsorbed and removed to reduce the concentration of dioxin in the exhaust gas, and the flue gas and exhaust gas are collected. The dioxin concentration in the dust ash can also be reduced by the prevention of dioxin generation and the decomposition reaction in the dust facility.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an exhaust gas treatment process illustrating an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator main body 2 Electric dust collector 3 Scrubber 4 Input material 5 Exhaust gas 6 Bottom ash 7 Flue 8 Fly ash 9 Chimney

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[Procedure amendment]

[Submission date] July 7, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

In the present invention, the activated carbon has a particle size of several mm to 10 μm in view of its handleability and adsorption efficiency.
It is preferable to use those having a degree.

Continued on the front page (72) Inventor Noboru Fujiwara 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Kurita Industry Co., Ltd.

Claims (1)

[Claims] 1. A dioxin release preventive material comprising activated carbon carrying an amine compound.