JP2001046994A - Method for decomposing dioxins and decomposing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat dioxins with high decomposition efficiency at a low temperature by reacting dioxins or dioxins-containing materials and a polyether compound or polyester compound under heating. SOLUTION: The dioxins or dioxins-containing materials, such as fly ashes, incineration ashes or soil contaminated with the dioxins, and dioxins-containing solids such as active carbon adsorbing the dioxins, and dioxins-containing gases, such as flue gases of incineration equipment, and the polyether compound, such as polyethylene glycol, polypropylene glycol or polyethylene oxide and the polyester compound, such as polyethylene terephthalate or polybutyrene terephthalate, are reacted under heating. As a result, the dioxins may be treated with the high decomposition efficiency at the low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently decomposing dioxins generated in an incinerator and the like, and a decomposing agent therefor.

[0002]

2. Description of the Related Art In an incinerator such as a refuse incinerator, a dioxin precursor such as a chlorinated aromatic compound such as chlorophenol or chlorobenzene or a chlorinated alkyl compound is generated during combustion. These dioxin precursors are:
When fly ash coexists, it becomes a dioxin (polychlorinated dibenzodioxin and polychlorinated dibenzofuran) due to its catalytic action, and becomes present in dust and exhaust gas. "Dioxins").

[0003] Conventionally, as a method for treating dioxins,
The following chemical treatment methods have been proposed. Dioxin-containing fly ash is heat-treated at 300 to 500 ° C in the presence of a dioxin formation inhibitor (Japanese Patent Laid-Open No. 4-2).
No. 41880). Specifically, fly ash is heated at 400 ° C. for 2 hours in the presence of pyridine vapor as a production inhibitor. Calcium polyoxyethylene alkyl ether carboxylate is sprayed on refuse or entrained in water sprayed for temperature control in a combustion furnace (JP-A-10-300)
031 publication). A dioxin or a dioxin-containing substance is brought into contact with a gaseous amine compound at a temperature of 100 ° C. or more and less than 300 ° C. (JP-A-10-272440). Dioxin is decomposed while supplying incineration ash and waste plastic to a gasification / melting device to gasify the plastic to generate a reducing atmosphere gas (Japanese Unexamined Patent Publication No.
No. 1-304410).

[0004]

Among the above-mentioned conventional chemical treatment methods, the above method requires a long heating time of 2 hours at a high temperature of 300 ° C. or more, so that heat energy increases and the treatment cost increases. . According to the method described above, the organic anion group of the calcium polyoxyethylene alkyl ether carboxylate is decomposed at a high temperature in the combustion furnace, so that the effect of preventing the release of dioxin becomes insufficient.

[0005] In addition, a good processing effect can be obtained by the above method, but there are the following problems. That is,
When processing fly ash from refuse incineration plants, etc., it is necessary to perform heavy metal fixing processing. However, when a treatment with a compound containing a nitrogen atom, such as an amine compound, is performed, these compounds remain in the fly ash and form heavy metals and complex ions. May not be obtained.

In the method (1), a large amount of heat energy is required because the waste plastic is partially burned at a high temperature above the ash melting point (for example, about 1300 ° C.) for gasification.

The present invention solves the above-mentioned conventional problems and does not require the use of a special reaction vessel, and can treat dioxins at a relatively low temperature with a high decomposition efficiency.
It is another object of the present invention to provide a method for decomposing dioxins and a decomposing agent which have excellent handleability and do not adversely affect the heavy metal fixing treatment.

[0008]

The method for decomposing dioxins of the present invention is characterized by reacting a dioxin or a dioxin-containing substance with a polyether compound or a polyester compound under heating.

The dioxin decomposer of the present invention is characterized by containing a polyether compound or a polyester compound.

The details of the decomposition mechanism of dioxins in the present invention are not clear, but are presumed as follows.

That is, by heating in the presence of water,
The polyether compound or polyester compound is hydrolyzed to produce alcohol compounds such as ethylene glycol and propylene glycol. Then, the dioxins are decomposed by reacting the resulting compounds such as alcohol compounds with the dioxins.

Since the polyether compound or polyester compound used in the present invention has almost no toxicity, handling of the drug becomes easy. Further, by selecting a polyether compound or a polyester compound that does not contain a nitrogen atom, there is no adverse effect on the heavy metal fixing treatment. And without using special containers, 100 ~
Dioxins can be efficiently decomposed and removed at a relatively low temperature of about 600 ° C.

As the polyether compound or polyester compound, wastes such as waste plastics can be used.

[0014]

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

The dioxin decomposer of the present invention contains a polyether compound or a polyester compound.

The polyether compound is not particularly limited, and the ether bond may be in either the main chain or the side chain. From the viewpoint of the heavy metal fixing treatment, the compound is preferably a compound containing no nitrogen, and examples thereof include polyethylene glycol, polypropylene glycol, and polyethylene oxide. Further, polyvinyl acetal, polyvinyl formal, polyvinyl butymal and the like are also exemplified.

On the other hand, as the polyester compound, polyethylene terephthalate, polyethylene naphthalate,
Examples thereof include polybutylene terephthalate.

Of these, polyethylene terephthalate and polyethylene naphthalate are used for applications such as fibers and bottles. In addition, polybutylene terephthalate is used as automobile parts and the like, and the present invention can use various products made of these materials and wastes thereof.

Also, various copolymers containing these compounds and materials obtained by mixing them can be used.
Note that the use of a nitrogen-containing polyether compound such as polyurethane is not excluded at all. Also,
Depending on the degree of polymerization, the polyether compound is classified into a liquid compound and a solid compound at room temperature. In the present invention, either compound may be used.

In the case where wastes such as PET bottles using these compounds as raw materials are used as the compounds used in the present invention, wastes other than polyvinyl chloride or the like containing chlorine atoms which cause generation of dioxins, waste plastics Are preferred. However, even if it contains a small amount of chlorine atom and generates dioxins, there is almost no problem because the dioxins generated by the action of the decomposing agent of the present invention are decomposed.

When these wastes are used, they may be used as they are, but are preferably used as crushed or pulverized materials.

In the method for decomposing dioxins of the present invention, such a decomposing agent is reacted with a dioxin-containing substance under heating.

The form of the dioxin-containing substance to be treated according to the present invention is not particularly limited. Fly ash, incinerated ash, soil contaminated with dioxins, dioxin-containing solids such as activated carbon adsorbed with dioxins, Examples include dioxin-containing gas such as flue gas of incineration equipment and dioxin-containing liquid such as scrubber water.

In the present invention, if the heating temperature is too low, the decomposition efficiency of dioxins is not sufficient, and if the heating temperature is higher than 600 ° C., the polymer added as a decomposing agent is oxidized, and the decomposing agent can contribute to the decomposition reaction. There is a problem that the amount is reduced or the processing temperature is too high, which is industrially disadvantageous. Therefore, the heating temperature is 100
The temperature is preferably from 600 to 600 ° C, particularly from 100 ° C to less than 400 ° C, especially from 200 to 300 ° C.

The method of adding the dioxin-decomposing agent of the present invention is not particularly limited, and it may be added in a plurality of portions or may be added in a plurality of portions.

The method of the present invention is specifically carried out by the following method.

When the dioxin-containing substance is a solid such as soil, incineration ash, and collected fly ash, the dioxin-containing substance and the decomposing agent of the present invention are kneaded.
It is carried out by heating to 100 to 600 ° C, preferably 100 to 400 ° C, particularly preferably 200 to 300 ° C.

When the dioxins and the dioxin-containing substances are present in a gaseous state or in the form of particles and suspended in an air stream such as an incineration exhaust gas, the air stream may have a flow rate of 100 to
In the region where the temperature is 600 ° C., the decomposing agent of the present invention is supplied into this gas stream.

When the dioxin-containing substance is treated in this manner, the amount of the release inhibitor of the present invention used depends on the substance to be treated, the treatment form, etc., but is different from that of the dioxin-containing substance such as fly ash. Alternatively, the amount of the active ingredient is preferably 0.1 to 10% by weight, particularly preferably 1 to 5% by weight, based on the amount of dust in the exhaust gas.

In the method of the present invention, the processing time is not particularly limited, but an excessively long processing time is disadvantageous in terms of processing cost. In the method of the present invention, generally 1 hour or less,
In particular, a sufficient decomposition rate can be obtained by a treatment for about 5 to 30 minutes.

In the present invention, in addition to the polyether compound or the polyester compound, if necessary, a chelating agent (piperazinedithiocarbamic acid, piperidinedithiocarbamic acid), a phosphoric acid-based heavy metal-fixing agent or a pH adjuster, or Other dioxin decomposers or dioxin generation inhibitors, for example, monoethanolamine, amines such as triethanolamine, ethanol, ethylene glycol, aliphatic alcohols such as propylene glycol, alkali, silicic acid, silicate, carbon disulfide, Sulfur dioxide may be used in combination.

In the present invention, a dioxin adsorbent such as activated carbon, activated coke, zeolite, silica gel and bentonite, preferably activated carbon or activated coke, particularly preferably activated carbon is used in combination with a polyether compound or a polyester compound. May be. For example,
A polyether compound is supported on these dioxin adsorbents, and is contacted with dioxin-containing water such as scrubber water, or is blown into a flue or a scrubber, collected, heated and adsorbed. Dioxins may be decomposed.

[0033]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 Assuming that all polyethylene glycol is hydrolyzed, the produced ethylene glycol is 5% by weight based on fly ash.
Fly ash (dioxins concentration 122.0n
g / g) was kneaded with a polyethylene mortar in a mortar, and the obtained kneaded material was charged into a three-necked flask heated to 300 ° C. and heated with stirring for 10 minutes. At this time, a cooling tube was attached to the opening to prevent the compound generated by heating from diffusing out of the flask. After that, measure the dioxin concentration of the obtained processed product and determine the dioxin decomposition rate from the dioxin concentration before and after the treatment,
The results are shown in Table 1.

[0035]

[Table 1]

Table 1 shows that dioxins can be efficiently decomposed and removed by using polyethylene glycol.

Example 2 A polyethylene terephthalate bottle containing soft drink was pulverized, and the obtained powder was adjusted to 5% by weight with respect to fly ash (dioxin concentration: 816.6 ng / g). Mixed. This mixture was treated as in Example 1 for 30
The mixture was charged into a three-necked flask heated to 0 ° C., and heated with stirring for 10 minutes. The dioxin concentration and the decomposition rate of the obtained treated product were determined. The results are shown in Table 2.

COMPARATIVE EXAMPLE 1 In Example 2, fly ash in which powder was not mixed was subjected to only heat treatment in the same manner, and the dioxin concentration and the decomposition rate of the obtained treated product were determined. The results are shown in Table 2. Was.

[0039]

[Table 2]

As is clear from Table 2, when the fly ash in which the powder was not mixed was heated (Comparative Example 1), the dioxin concentration increased as compared with the raw ash. On the other hand, fly ash mixed with powder (Example 2) provided a high decomposition rate.

From the above results, it is apparent that the concentration of dioxins in the incineration ash can be reduced by mixing the polyethylene terephthalate bottle, which is a waste, with the incineration ash discharged from the incineration plant and heating it. .

[0042]

As described above in detail, according to the present invention, it is possible to decompose and remove dioxins at a relatively low temperature without using a special reaction vessel, and it is excellent in handleability. In addition, a dioxin-decomposing agent that does not adversely affect the heavy metal fixing treatment can be efficiently decomposed.

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[Procedure amendment]

[Submission date] August 31, 1999 (1999.8.3)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

BACKGROUND OF THE INVENTION incinerators such as refuse incinerators, during combustion, chlorophenols, dioxins <br/> Precursor chlorinated aromatics or chlorinated alkyl compounds such as chlorobenzene occurs. These dioxins before driving body,
When fly ash coexist dioxins in the catalysis (polychlorinated dibenzodioxins and polychlorinated dibenzofurans), and comes to exist in the dust and the exhaust gas (in the present invention together with driving front dioxins and dioxins body, Hereinafter referred to as "dioxins").

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The polyether compound is not particularly limited, and the ether bond may be in either the main chain or the side chain. From the viewpoint of the heavy metal fixing treatment, the compound is preferably a compound containing no nitrogen, and examples thereof include polyethylene glycol, polypropylene glycol, and polyethylene oxide. Further, polyvinyl acetal, polyvinyl formal, even such Poribinirubuchi La Lumpur are exemplified.

Claims (4)

[Claims] 1. A method for decomposing dioxins, comprising reacting a dioxin or a dioxin-containing substance with a polyether compound or a polyester compound under heating. 2. A method for decomposing dioxins, wherein the heating temperature is 100 to 600 ° C. 3. The method for decomposing dioxins according to claim 1, wherein the polyether compound or the polyester compound is waste. 4. A dioxin decomposer comprising a polyether compound or a polyester compound.