JP2002210443A - Method and apparatus for detoxicating waste containing harmful material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detoxicate waste with the thermal decomposition and/or the volatilization of harmful materials such as dioxins in the waste by heating the waste uniformly. SOLUTION: Fly ash 4 (the waste) discharged from a refuse incineration equipment is charged into a vessel 5 to form a fluidized bed 12 of the fly ash 4 in the vessel and simultaneously the fluidized bed 12 is stirred with stirring blade 7 and heated with a heater 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detoxifying waste containing harmful substances, and more particularly to a method for thermally decomposing and / or volatilizing harmful substances such as dioxins in waste by uniform heating of waste. The present invention relates to a method and an apparatus for detoxifying waste containing harmful substances, which can be easily and reliably detoxified.

[0002]

2. Description of the Related Art Conventionally, for example, wastes discharged from refuse incineration facilities contain organic halogen compounds such as dioxins which are harmful to the human body. Has been performed.

Here, the waste containing harmful substances is mainly composed of inorganic substances such as incineration residues discharged from refuse incineration facilities, residues discharged from refuse melting facilities, contaminated soil, and adsorption treatment residues. Contains harmful organic halogen compounds such as dioxins.

[0004] Here, incineration ash discharged directly from the combustion chamber of the refuse incineration facility to the outside of the furnace and fly ash contained in the combustion exhaust gas of the refuse are collectively referred to as incineration residues.

In particular, since fly ash in flue gas contains a large amount of the above-mentioned harmful substances, various methods for detoxifying harmful substances have been proposed. One of them is JP-A-9-225.
No. 431 discloses the following method (hereinafter, this method is referred to as Conventional Technique 1).

The fly ash collected from the exhaust gas is stirred and heated in an oxygen-deficient state, and held for a predetermined time to thermally decompose the fly ash dioxins. Oxides or chlorides of alkali metals or alkaline earth metals are added to lower the thermal decomposition reaction temperature of dioxins, and fly ash is heated by a heating medium recovered from a refuse incinerator to reduce dioxins. Harmless.

According to the above-mentioned prior art 1, thermal decomposition reaction of dioxins is performed by adding a hydroxide of an alkali metal or an alkaline earth metal or a chloride of an alkali metal or an alkaline earth metal to fly ash. Since the temperature can be reduced, it is possible to effectively decompose dioxins by heat, and to reduce the operating cost.

As another method of detoxifying incineration residues, Japanese Patent Application Laid-Open No. 10-80675 discloses the following method (hereinafter, this method is referred to as prior art 2).

[0009] In a method for treating incineration ash of a refuse incinerator, wherein the incineration ash discharged from the refuse incinerator is collected by a dust remover,
The recovered incinerated ash is granulated by a granulator, and then
The granulated product is supplied to a fluidized bed incinerator and heated to a temperature of 300 ° C. or higher to detoxify aromatic chlorides contained in the granulated product.

According to the above prior art 1, the incinerated ash is reduced to 300
By heating to a temperature of at least ° C., the amount of organic chlorine compounds in the incineration ash can be reduced.

[0011]

However, the above-mentioned prior art 1 has the following problems.

In order to heat the fly ash to thermally decompose the dioxins in the fly ash, the fly ash 4 is placed in a storage tank 1 (container) having a heating means 2 and a stirring blade 3, as shown in FIG. Since the fly ash 4 is heated by the heating means 2 while stirring the fly ash 4 by rotating the stirring blades 3,
Depending on the stirring conditions such as the rotation speed of the stirring blade 3, the fly ash 4
May not be sufficiently stirred. If the fly ash is not sufficiently stirred in this manner, the thermal decomposition of the dioxins in the fly ash will not be sufficiently performed, which will hinder the detoxification of the fly ash.

On the other hand, the above-mentioned prior art 2 has the following problems.

Since the incinerated ash needs to be granulated by a granulator, the granulation takes time and labor, and if the inside of the granulated material is not sufficiently heated, the harmless dioxins contained in the incinerated material are harmless. Can not be achieved enough.

Accordingly, an object of the present invention is to provide a harmful substance which can easily and reliably detoxify harmful substances such as dioxins by thermal decomposition and / or volatilization by uniformly heating waste containing harmful substances. It is an object of the present invention to provide a method for detoxifying waste containing substances.

[0016]

According to the first aspect of the present invention,
A waste containing an organic halogen compound such as dioxin is charged into a container, and a fluidized bed of the waste is formed in the container. At the same time, the fluidized bed is stirred by a stirring means and heated by a heating means. Thus, the organic halogen compound in the waste is thermally decomposed and / or volatilized to detoxify the waste.

According to a second aspect of the present invention, the fluidized bed is formed by blowing at least the hot air blown from the bottom of the container through a dispersion plate and stirring the waste in the container. It is characterized by being performed by.

[0018] In the invention according to claim 3, the stirring means comprises:
It is characterized by comprising a stirring blade provided in the container.

According to a fourth aspect of the present invention, the heating means includes:
It is characterized by comprising a heater provided on the outer periphery of the container.

[0020] The invention according to claim 5 is characterized in that exhaust gas from the container is removed by a dust removal device provided above the fluidized bed or outside the container, and then discharged.

According to a sixth aspect of the present invention, a partition is provided between an inlet of the waste into the container and a suction port of the dust remover, and the waste is directly sucked into the dust remover. It is characterized in that it is not performed.

The invention according to claim 7 is characterized in that the exhaust gas from the vessel is treated via a fluidized bed catalyst or a moving bed catalyst.

[0023] The invention according to claim 8 is characterized in that:
It is characterized by using an organic oxidation decomposition catalyst using a noble metal as an active component in a metal state.

According to a ninth aspect of the present invention, the exhaust gas from the container is supplied to a combustion section of a high-temperature device.

According to a tenth aspect of the present invention, a container into which waste containing an organic halogen compound such as dioxin is charged, a stirring blade provided in the container, and a heater provided on the outer periphery of the container. The flow of the waste into the container by blowing at least the hot air blown into the container from the bottom of the container via the dispersion plate into the container and stirring the waste in the container. A layer is formed, and the fluidized bed is heated by the hot air and the heater while being stirred by the stirring blade, whereby the organic halogen compound in the waste is thermally decomposed and / or volatilized. Have

The invention according to claim 11 is characterized in that a dust remover is provided above the fluidized bed or outside the vessel.

According to a twelfth aspect of the present invention, a partition is provided between an inlet of the waste into the container and a suction port of the dust removing device.

A thirteenth aspect of the present invention is characterized in that a fluidized bed catalyst tower or a moving bed catalyst tower for treating exhaust gas from the vessel is provided.

[0029]

Next, an embodiment of a method for detoxifying waste containing harmful substances according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing one embodiment of the method for detoxifying waste containing harmful substances according to the present invention.

In FIG. 1, reference numeral 5 denotes a cylindrical container, which is disposed of by a dust remover such as a bag filter (not shown) of a refuse incinerator and disposed of in a flue gas containing harmful substances. Fly ash 4 as an object is injected into the container 5 from the input port 6 by a fixed amount. Reference numeral 7 denotes a stirring blade provided in the container 5, and reference numeral 8 denotes an electric heater provided on the outer periphery of the container 5. The heater 8 assists the heating of the fly ash 4 by hot air described later, and uniformly heats the fly ash 4 to a predetermined temperature.

The bottom of the container 5 is partitioned by a porous dispersion plate 9 to form a wind box 10. Hot air 11 having a temperature of about 350 to 450 ° C. is blown into the wind box 10 from a heated air inlet. In this way, when the hot air 11 is blown into the container 5 through the dispersion plate 9, a fluidized bed 12 of the fly ash 4 is formed in the container 5. Fluidized bed 12
Is heated by the hot air 11 and the heater 8 while being stirred by the stirring blade 7 rotating at a speed of about 5 to 30 rpm.

In the case of a waste such as fly ash 4 having a small particle size, the fluidized bed 12 is formed more favorably by stirring by the stirring blades 7 in addition to the blowing of the hot air 11.

Numeral 13 denotes a dust remover provided above the fluidized bed 12 for removing the exhaust gas from the container 5. The dust removing device 13 may be provided outside the container 5.

When the dust removing device 13 is provided inside the container 5, for example, on the upper inside, the fly ash separated by the dust removing device 13 falls directly into the fluidized bed portion of the container 5. It is not necessary to newly install a fly ash return pipe or the like, and a simple device configuration is achieved.

On the other hand, the purpose of the present invention is to volatilize the organic halogen compound from the waste containing harmful substances, and the organic halogen compound volatilized in the fluidized bed 12 in the container 5 is discarded in the dust removing device 13. In order to prevent re-adsorption to an object, the temperature of the dust removing device 13 needs to be maintained higher than the temperature of the fluidized bed 12.

In order to control the temperature in the dust remover 13, it is necessary to isolate the fly ash inlet 6 newly introduced from the outside of the container 5 from the dust remover 13. This is because the temperature of the dust removing unit is lowered by the waste input at a low temperature. This can be achieved by installing the dust remover 13 away from the fly ash inlet 6, for example, outside the container 5.

If a partition is provided between the charging port 6 and the suction port of the dust removing device 13, even when the dust removing device 13 is installed inside the container 5, the gas temperature around the dust removing device 13 can be reduced. It can be effectively prevented. That is, when fly ash at normal temperature is put into the container 5, the temperature of the surrounding gas decreases, and the gas whose temperature has dropped is sucked into the dust removing device 13. By providing the partition, it is possible not only to prevent the temperature of the gas from lowering but also to effectively prevent fly ash charged into the container 5 from being directly sucked into the dust removing device 13. As a result, the efficiency of removing organic halogen compounds from fly ash can be significantly improved. Also,
Due to the effect of preventing the temperature of the gas from lowering, it is possible to reduce the energy required for heating during the heat treatment and the blowing gas used for promoting volatilization. In FIG. 1, the function of the partition is made by setting the length of the inlet 6 to a length that reaches the inside of the fluidized bed 12.

Numeral 14 denotes a fluidized bed type catalyst tower, which removes the volatile organic compounds which have been removed from the exhaust gas after the dust removal treatment from the dust remover 13. In the present invention,
Fluidized bed type or moving bed type catalysts can be applied to the detoxification treatment of volatile organic halogen compounds.

When the organic halogen compound is rendered harmless using a catalyst, the contact efficiency between the organic halogen compound and the catalyst can be increased as compared with the case where the organic halogen compound is not separated from fly ash. In particular, in the case of treating with a fluidized bed type or moving bed type catalyst, the contact efficiency with the catalyst can be higher than in the case of treating with a fixed bed catalyst. That is, even when a fine-grained catalyst capable of keeping the contact efficiency with the organic halogen compound contained in the exhaust gas high can be used, the catalyst is entrained in the exhaust gas by using a fluidized bed type or a moving bed type. As a result, an increase in pressure loss due to clogging due to dust entering the catalyst layer can be effectively avoided as compared with a fixed bed catalyst. As a result, a higher decomposition efficiency of the organic halogen compound can be obtained. In addition, since the contact efficiency is high, the required amount of the catalyst can be reduced, and the waste can be detoxified at low cost.

Further, when the gas discharged after the heat treatment is treated with an organic oxidative decomposition catalyst containing a noble metal, the catalyst using a noble metal as a catalytically active species is less effective than when a catalyst having an oxide type catalytically active species is used. Since it has a higher oxidative decomposition ability of organic substances, it is possible to completely oxidize and decompose an organic halogen compound to completely render it harmless. In addition, since it has the ability to effectively and completely oxidize and decompose dioxin-related substances and other organic compounds that cause the synthesis of dioxins and other harmful substances, the synthesis of dioxins and other harmful substances in treated exhaust gas is also effective. Can be prevented.

On the other hand, when an oxide catalyst having an inferior activity to a catalyst containing a noble metal in oxidizing activity of an organic substance is used, an organic halogen compound or another organic compound cannot be completely oxidized and decomposed. As a result, harmful substances may be synthesized in the exhaust gas after the treatment.

The fly ash 4 is formed in the vessel 5 from 350 by the formation of a fluidized bed by blowing in at least hot air from the hot air 11 and stirring and forced stirring by the stirring blade 7 and heating by the hot air 11 and heater 8. It is uniformly heated to a temperature of about 450 ° C. As a result, harmful substances such as dioxin contained in the fly ash 4 can be reliably detoxified by thermal decomposition and / or volatilization. The fly ash 4 from which the harmful substances have been rendered harmless is sequentially discharged out of the container 5 from the discharge port 15.

The formation of the fluidized bed can be carried out by vibrating the container 5 or vibrating the fly ash 4 by ultrasonic waves, instead of blowing hot air. Also,
The stirring of the fly ash 4 in the container 5 can be performed by blowing gas or the like in addition to the stirring blade 7. Further, the container 5
Heating of the fly ash 4 in the inside may be performed by the retained heat of the combustion exhaust gas from the refuse incineration equipment other than the electric heater 8.
In order to heat the fly ash 4 more efficiently, the stirring blade 7
It is also possible to provide a heater on the rotating shaft of the stirring blade 7 for heating.

The stirring blade 7 may have a rake-shaped blade attached to the stirring arm. However, in the case of fly ash with poor fluidity,
If a fixed bar is separately installed between the rotating blades, it is possible to prevent the stirring efficiency from being lowered due to the rotation with the rotating blades.

The above description has been made by taking fly ash as an example of waste. However, even when applied to waste such as incinerated ash,
Needless to say, the same effect as in the case of fly ash can be obtained.

It is also possible to directly supply the exhaust gas from the container to the combustion section of a heating furnace or a waste incinerator to thermally decompose the above harmful substances. Is unnecessary.

[0048]

As described above, according to the present invention, a fluidized bed of waste is formed in a container,
The waste can be heated uniformly by stirring the fluidized bed by the stirring means and heating by the heating means, thereby thermally decomposing and / or volatilizing harmful substances such as dioxin in the waste. Industrially useful effects such as easy and reliable detoxification can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a method for detoxifying waste in a refuse incineration plant according to the present invention.

FIG. 2 is a schematic sectional view showing a fly ash heating device in a conventional fly ash detoxification method.

[Explanation of symbols]

 1: storage tank 2: heating means 3: stirring blade 4: fly ash 5: container 6: fly ash inlet 7: stirring blade 8: heater 9: dispersion plate 10: wind box 11: hot air 12: fluidized bed 13: dust removal Device 14: Catalyst tower 15: Fly ash outlet after treatment

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F23J 1/00 B09B 3/00 303J 303K 303L 303P (72) Inventor Iwa ▲ Saki ▼ Toshihiko 1-Chome-1, Marunouchi, Chiyoda-ku, Tokyo No. 2 Nihon Kokan Co., Ltd. (72) Inventor Hajime Akiyama 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masashi Ayukawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo No. Nippon Kokan Co., Ltd. F-term (reference)

Claims (13)

[Claims] 1. A waste containing an organic halogen compound such as dioxin is charged into a container, and a fluidized bed of the waste is formed in the container. At the same time, the fluidized bed is stirred by stirring means. A method for detoxifying waste containing harmful substances, characterized in that the waste is detoxified by heating by a heating means and thus decomposing and / or volatilizing the organic halogen compound in the waste. 2. The method according to claim 1, wherein the formation of the fluidized bed is performed by hot air blown from a bottom of the container through a dispersion plate and at least the hot air blown out of the waste in the container. The method for detoxifying waste containing harmful substances according to claim 1. 3. The stirrer according to claim 1, wherein the stirrer comprises a stirrer provided in the vessel.
The detoxification method for waste containing hazardous substances as described in the above. 4. The waste material containing harmful substances according to claim 1, wherein said heating means comprises a heater provided on an outer periphery of said container. Detoxification method. 5. The method according to claim 1, wherein the exhaust gas from the container is discharged after dust is removed by a dust removing device provided above the fluidized bed or outside the container. The detoxification method for waste containing hazardous substances as described in the above. 6. An inlet for the waste into the container,
The harmless waste containing harmful substances according to claim 5, wherein a partition is provided between the dust remover and a suction port of the dust remover so that the waste is not directly sucked into the dust remover. Method. 7. The harmful substance according to claim 1, wherein the exhaust gas from the vessel is treated through a fluidized bed catalyst or a moving bed catalyst. Detoxification method of waste containing 8. The method for detoxifying waste containing harmful substances according to claim 7, wherein an organic matter oxidative decomposition catalyst using a noble metal as an active component in a metal state is used as the catalyst. 9. The harmless waste containing harmful substances according to claim 1, wherein the exhaust gas from the container is supplied to a combustion section of a high-temperature apparatus. Method. 10. A container into which waste containing an organic halogen compound such as dioxin is charged, a stirring blade provided in the container, and a heater provided on an outer periphery of the container, wherein a bottom portion of the container is provided. From the hot air blown into the container via the dispersion plate and at least the hot air blow out of the stirring of the waste in the container, a fluidized bed of the waste is formed in the container, The fluidized bed is heated by the hot air and the heater while being stirred by the stirring blade, and thus the organic halogen compound in the waste is thermally decomposed and / or volatilized, and contains a harmful substance. Waste harmless device. 11. The detoxifying apparatus for waste containing harmful substances according to claim 10, wherein a dust removing apparatus is provided above the fluidized bed or outside the container. 12. A harmful substance containing harmful substance according to claim 10, wherein a partition is provided between an inlet of said waste into said container and a suction port of said dust removing device. Waste harmless device. 13. The method according to claim 10, wherein a fluidized-bed catalyst tower or a moving-bed catalyst tower for treating exhaust gas from the vessel is provided. Detoxification equipment for waste containing harmful substances.