JP2003200022A - Method for treating hazardous material of exhaust gas and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating hazardous materials, such as acidic gas and dioxins in exhaust gas capable of treating the hazardous materials at a high removal rate and treating these materials at a low cost by reducing the amount of the chemical to be added, and an apparatus for the same. <P>SOLUTION: The apparatus has a bag filter 10 for separating fly ash 22 from the exhaust gas, a scrubber 11 for removing the hazardous materials from the exhaust gas separated of the fly ash, a fly ash mixing vessel 12 for adding and mixing an acid 31 to and with the separated and captured fly ash 22, and a decomposing vessel 14 built in with means for mixing the fly ash 22 and the waste water of the scrubber 11 and strongly agitating the mixture while slurrying the mixture, and means for oxidizing and decomposing the hardly decomposable materials contained in the fly ash in the presence of hydroxyl radicals. The makeup water 24 of the scrubber 11 is the makeup water containing active carbon 30 and the hazardous materials, such as acidic gas and hardly decomposable materials, in the exhaust gas are removed by the active carbon. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to treatment of hardly decomposable substances such as dioxins contained in exhaust gas discharged from a boiler, incinerator, or melting furnace. The present invention relates to a method and an apparatus for treating harmful substances in exhaust gas, in which ash is mixed with water such as industrial waste water to form a slurry, which is oxidatively decomposed by hydroxy radicals having strong oxidizing power.

[0002]

2. Description of the Related Art Exhaust gas discharged from a boiler, incinerator, or melting furnace contains harmful substances such as sulfur oxides, nitrogen oxides, hydrogen chloride, heavy metals, and dioxins, which have a harmful effect on the human body and the environment. Has been done. Among them, persistent substances such as dioxins are highly toxic and have toxicity such as carcinogenicity and teratogenicity, so that they have recently been regulated by strict environmental standards. The dioxins are organic chlorine compounds such as polychlorinated dibenzofuran (PCDF) and polychlorinated dibenzo-para-dioxin (PCDD), which are unintentionally generated in the process of burning the organic compound under the coexistence of chlorine. .

The organic chlorine compounds such as dioxins and PCBs are chemically stable and hardly decomposable substances, and in an incinerator or the like, in a temperature range of about 250 to 350 ° C.,
It may be resynthesized by contact between a precursor substance such as chlorobenzene and fly ash, or contact between inorganic chlorine, air, water and the like with unburned carbon using unburned carbon as a starting material. As a method for suppressing the emission of the hardly decomposable substance, in the combustion process, combustion control is performed to improve the combustion state and prevent re-synthesis of the hardly decomposable substance in the temperature range, and further in the temperature range for decomposable substance decomposition. Reburning and the like can be mentioned, but it is difficult to eliminate the generation of hardly decomposable substances even by these methods.

Therefore, as a method for treating solid matter such as fly ash containing a hardly decomposable substance, a melting method, a gas phase hydrogen reduction method,
Reductive heating dechlorination system, supercritical hydroxylation decomposition system, sodium metal dispersion system, photochemical decomposition system, oxidative decomposition system, etc.
Although various methods can be mentioned, among them, the oxidative decomposition method using a hydroxy radical having a strong oxidizing power is considered to be a highly cost effective method because of its high efficiency of removing hardly decomposable substances. Japanese Unexamined Patent Application Publication No.
01-137803 is a mixture of incineration ash containing a hardly decomposable substance with water to form a slurry, and at the same time as or after slurrying in an acidic state, in a neutral to alkaline state and in the presence of hydroxy radicals. A method for oxidatively treating the hardly decomposable substance is provided.

Furthermore, the present inventors have proposed a processing method as shown in FIG. 9 in Japanese Patent Application No. 2001-72826 (not known) as an invention that further develops the above technique. In this treatment method, the incineration ash 04 containing the hardly decomposable substance discharged from the incinerator is mixed with the waste water 05 in the fly ash dissolution tank 01 to form a slurry, and the acid 07 is added in the pretreatment tank 010. After depositing a hardly decomposable substance on the surface of incineration ash,
Reaction tank 02 in which alkali 08 was added to make it alkaline
In addition, the incineration ash is rendered harmless by oxidatively decomposing the hardly decomposable substance in the presence of hydrogen peroxide 06 and hydroxy radicals generated by ozone generated by the ozone generator 03.

On the other hand, apart from the hardly decomposable substance, acid gas such as hydrogen chloride, which is a harmful component contained in exhaust gas, is mainly removed by neutralization reaction, and the treatment method is a wet method. There are semi-dry method and dry method.
It is treated by reacting with an alkaline agent such as Ca (OH) ₂ (slaked lime). Among them, a dry method in which an alkaline powder such as slaked lime is blown into an exhaust gas flue or a bag filter is widely used as a method that can be incorporated into an existing apparatus without requiring a dedicated apparatus.

Japanese Patent Laid-Open No. 2000-176244 discloses a method of removing a hardly decomposable substance and supplying slaked lime to remove an acid gas by using such a method. As shown in FIG. 8, such a treatment method includes an incinerator 1
The exhaust gas from 01 is cooled by the waste heat boiler 102 and the desuperheater 103 supplied with the slaked lime slurry, and the activated carbon powder and the slaked lime powder are supplied, and then the solid matter is collected by the dust collector 104. It consists of a removal step of removing fly ash, and a decomposition step of supplying acid and industrial water to decompose and detoxify dioxins in the solid matter. Thus, the fly ash can be detoxified in the dry exhaust gas treatment facility at the same time.

[0008]

However, in the above exhaust gas treatment equipment, no particular treatment is carried out for harmful substances remaining in the exhaust gas that has passed through the dust collector,
Although it is a simple facility, it is difficult to meet the strict emission regulations for harmful substances. In addition, if a treatment facility for hardly decomposable substances is installed in parallel for the above-mentioned exhaust gas treatment, there is a problem that a large amount of chemicals must be used. This is because most of the exhaust gas is discharged as acidic, but after being once made alkaline with the alkaline agent used in the acid gas removal treatment, it has to be further acidified to extract the hardly decomposable substance, It is difficult to adjust pH, and the amount of alkali and acid added increases, resulting in an increase in drug cost.

Furthermore, a non-degradable substance is used in the above-mentioned Japanese Patent Application No. 20.
In the treatment of oxidative decomposition with hydroxy radicals such as 01-72826, it is necessary to further add an alkaline agent in order to bring it into an alkaline state in which the hydroxy radicals are easily generated, and a larger amount of the drug is required. come.
In view of the problems of the prior art, the present invention is capable of treating harmful substances such as hardly decomposable substances such as acid gas and dioxins in exhaust gas with a high removal rate and reducing the amount of chemicals to be added. It is an object of the present invention to provide a method for treating harmful substances in exhaust gas and an apparatus therefor capable of performing treatment at low cost.

[0010]

Therefore, in order to solve the above problems, the present invention provides, as an invention according to claim 1, exhaust gases discharged from a combustion apparatus such as a boiler, a melting furnace, an incinerator, dioxins and the like. In the method for treating a harmful substance containing a hardly decomposable substance, the exhaust gas is guided to a scrubber, and water containing an adsorbent for a hardly decomposable substance is sprayed in the scrubber to acid gas and hardly decomposable substance in the exhaust gas. We propose a method for treating harmful substances in exhaust gas, which is characterized by removing the harmful substances.

Further, in the invention according to claim 2, the fly ash is separated from the exhaust gas on the upstream side of the scrubber, an acid is added to the separated fly ash, and the fly ash in an acidic state and the scrubber are separated. It is characterized in that the discharged wastewater is mixed to form a slurry, and the slurry is oxidatively decomposed in the presence of hydroxy radicals to render the hardly decomposable substance contained in the slurry harmless. According to such an invention, by adding and spraying a hardly decomposable substance adsorbent such as activated carbon or zeolite to the scrubber makeup water, the acidic gas can be removed by the scrubber and the hardly decomposable contained in the exhaust gas. Of organic substances and heavy metals can be adsorbed and separated by the adsorbent, and harmful substances in exhaust gas can be treated with a high removal rate. At this time, an alkaline agent may be added to the scrubber makeup water to remove the acidic gas by a neutralization reaction.

By mixing the scrubber wastewater containing the harmful substances with the fly ash to form a slurry and subjecting it to an oxidative decomposition treatment, the wastewater can be efficiently treated without separately providing a treatment device. Furthermore, in such a treatment, it is possible to omit the acid gas removal treatment by the supply of the alkaline agent which is performed before the fly ash separation means as in the above-mentioned conventional technique. Therefore, it is possible to reduce the supply amount of the acid when the acid is added to precipitate the hardly decomposable substance.

Further, as described in claim 3, by crushing the slurry at a stage before the oxidative decomposition or at the same time as the oxidative decomposition, the fly ash in the slurry is crushed to increase the surface area of the fly ash, The contact with the hydroxy radical becomes large, the decomposition reaction is carried out in a short time, and the hardly decomposable substance can be rendered harmless with a high decomposition rate.

The invention according to claim 4 is the method for treating harmful substances in exhaust gas according to claim 1 or 2, wherein an alkaline agent is supplied to the exhaust gas containing fly ash to remove the acidic gas in the exhaust gas. It is characterized in that the supply amount of the alkaline agent is set so that the pH concentration of is about pH 8 or less. Further, the invention according to claim 5 is the method for treating harmful substances in exhaust gas according to claim 1 or 2, wherein an alkaline agent is supplied to the fly ash-containing exhaust gas to remove the acidic gas in the exhaust gas. The supply amount is about 2 equivalent ratios or less.

According to the present invention, the amount of the acid added in the next step can be reduced by reducing the amount of the alkaline agent supplied to the exhaust gas discharged from the combustion device to be smaller than the conventional amount, and the treatment cost can be suppressed. It becomes possible. The amount of the alkaline agent supplied is preferably such that the alkaline agent does not remain in the fly ash, and the pH concentration is about pH 8 or less,
Alternatively, the equivalent ratio of the alkaline agent is 2 or less, preferably 1.4 or less. Incidentally, it is considered that the hardly decomposable substance remains in the exhaust gas by reducing the supply amount of the alkaline agent, but since it can be removed by a scrubber spraying the adsorbent-containing water located in the latter stage, There is no fear of leaving harmful substances.

The invention according to claims 6 to 10 relates to an exhaust gas treating apparatus, and the invention according to claim 6 separates fly ash from exhaust gas discharged from a combustion apparatus such as a boiler, a melting furnace, or an incinerator. And a scrubber for removing harmful substances such as acidic gas from the exhaust gas from which the fly ash has been separated, in which a acid is added to the fly ash collected by the fly ash separating means and mixed. Means, a means for supplying scrubber wastewater to the fly ash to form a slurry and performing strong stirring, and means for oxidatively decomposing hardly-decomposable substances such as dioxins contained in the slurry in the presence of hydroxy radicals. Along with, the scrubber has a means for adding a hardly-decomposable substance adsorbent to the makeup water of the scrubber,
The adsorbent separates and collects the hardly decomposable substance in the exhaust gas, and the oxidative decomposition means decomposes and renders the hardly decomposable substance harmless with the fly ash.

Further, the invention according to claim 7 is a hazardous substance treating apparatus comprising a scrubber for removing harmful substances such as acid gas from exhaust gas discharged from a combustion device such as a boiler, a melting furnace, an incinerator, and the like. A means for strongly stirring the slurry containing the fly ash separated and collected by, and a means for oxidatively decomposing a hardly decomposable substance such as dioxins contained in the slurry in the presence of hydroxy radicals, and the scrubber is provided. The scrubber has a means for introducing a hardly decomposable substance adsorbent into the makeup water, and the adsorbent separates and collects the hardly decomposable substance in the exhaust gas, and the oxidative decomposition means causes the hardly decomposed substance to be absorbed together with the fly ash. It is characterized by decomposing and detoxifying degradable substances.

Further, as in the eighth aspect of the present invention, it is preferable that a means for crushing the fly ash is provided upstream of the decomposing means. According to this invention, the acid gas, the hardly decomposable substance, and the heavy metals in the exhaust gas can be treated with a high removal rate, similarly to the effects of the first to third aspects.
It should be noted that the scrubber may be arranged in a plurality of stages in series depending on the processing conditions of the harmful substance.

According to a ninth aspect of the present invention, in the hazardous substance treating apparatus according to the sixth or seventh aspect, wherein means for supplying an alkaline agent to the fly ash-containing exhaust gas is provided, the fly ash has a pH concentration of about pH 8 or less. The supply amount of the alkaline agent is set so that Further, the invention according to claim 10 is the hazardous substance treating apparatus according to claim 6 or 7, wherein means for supplying an alkaline agent to the fly ash-containing exhaust gas is provided, wherein the alkaline agent supplying means has a ratio of about 2 equivalents. It is characterized by supplying the following alkaline agents. According to this invention, the same effect as that of the invention described in claim 4 or 5 can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless specifically stated otherwise, and are merely illustrative examples. Not too much. FIG. 1 is a schematic configuration diagram of an apparatus for treating persistent substances according to a first embodiment of the present invention, and FIGS. 2 to 7 are schematic configuration diagrams of second to seventh examples which are different embodiments of FIG. is there.

In FIGS. 1 to 7, reference numeral 10 denotes exhaust gas 20.
The bag filter for separating the fly ash 22 from the exhaust gas may be any device capable of solid-gas separation such as an electrostatic precipitator or a multi cyclone. Reference numeral 11 is a scrubber that sprays makeup water 24 to remove soot dust and acid gas in the exhaust gas. Activated carbon 30 is added to the makeup water 24 sprayed by the scrubber 11 to simultaneously remove persistent substances. Composed. The activated carbon 30 can be replaced with zeolite having an adsorption function. Reference numeral 12 denotes a fly ash mixing tank, which has a supply port for the acid 31 and the fly ash 22 and a mixing means such as a stirring blade or bubbling means. Reference numeral 14 is a strong stirring means 16, an air diffuser 15 for ozone 28, and hydrogen peroxide 2
Reference numeral 6 designates a decomposition tank equipped with an oxidative decomposition means for generating hydroxy radicals and promoting oxidative decomposition, and numeral 13 is a crusher equipped with a crushing means for crushing the fly ash.

The crusher 13 is, for example, a high-speed rotary impact crusher such as a disc mill or a pin mill, a roller mill, a ball mill, a stirring type crusher, a jet mill, a colloid mill, a disperser, and a mixer. It is possible to use a device such as a machine that can atomize incinerated ash to a predetermined particle size by dispersing and mixing, but especially fly ash and balls are inserted into a high hardness container and this is driven by a motor. A ball mill in which fly ash collides with the balls, the walls of the container, and the fly ash to crush the fly ash in a short time by rotating and vibrating with a ball mill, a rolling ball mill, a vibrating ball mill, a planetary ball mill, etc. are suitable. ing. Incidentally, these devices may be of batch type or continuous type, respectively.

In FIG. 1, first, exhaust gas 20 is slaked lime 2.
After being blown with 1 to remove the acid gas and the like, the bag ash 10 separates the fly ash 22 and the exhaust gas.
The supply amount of the slaked lime 21 is preferably such that the slaked lime 22 does not remain in the fly ash 22.
It is advisable to supply so that the concentration is about pH 8 or less, or the equivalent ratio of the alkaline agent is 2 or less, preferably 1.4 or less. As a result, the amount of acid added in the next step can be reduced, and the chemical cost can be reduced. The exhaust gas from which the fly ash has been separated is introduced into the scrubber 11, and the scrubber 11 sprays the makeup water 24 into which the activated carbon 30 has been added, so that the acidic gas, the hardly decomposable substance, and the heavy metals remaining in the exhaust gas are discharged. Hazardous substances are absorbed and removed. The scrubber may be provided in a plurality of stages depending on the concentration of harmful substances in the exhaust gas.

On the other hand, the fly ash 22 separated and collected by the bag filter 10 is introduced into the fly ash mixing tank 12 to generate the acid 31.
Is added, the hardly decomposable substance in the fly ash is deposited and introduced into the decomposition tank 14. In the decomposition tank 14, the fly ash is mixed with the scrubber wastewater 25 and oxidatively decomposed in the presence of hydroxy radicals. In the decomposition tank 14, the fly ash and the scrubber wastewater 25 are strongly stirred by the strong stirring means 16, and the fly ash is generated by the hydroxy radical having a strong oxidizing power generated by the hydrogen peroxide 26 and the ozone 28. And the persistent substances contained in the scrubber drainage are decomposed and rendered harmless.

In the present embodiment, hydrogen peroxide and ozone are used as the means for generating the hydroxy radicals, but the means is not particularly limited as long as it is a means for generating the hydroxy radicals, and hydrogen peroxide, ozone, Using at least two or more of photocatalyst or ultraviolet irradiation, for example, reaction between hydrogen peroxide and ozone, ozone oxidation under high pH, ozone oxidation under ultraviolet irradiation, ultraviolet irradiation in the presence of hydrogen peroxide, Hydroxyl radicals can be generated by UV irradiation in the presence of chlorite, photooxidation in the presence of photocatalyst, oxidation by Fenton's reagent, and the like. In particular, ozone oxidation in the presence of hydrogen peroxide or ozone oxidation under high pH is preferable because it is difficult for ultraviolet rays to pass through in the fly ash made into a slurry. Of course, the decomposition is not limited to this, and decomposition by a single oxidizing action of hydrogen peroxide, ozone or the like is also possible.

At this time, it is preferable that the decomposition tank 14 is in an alkaline state where hydroxy radicals are easily generated. The slurry that has been subjected to the oxidative decomposition treatment can be solid-liquid separated as drainage 27 after sufficiently removing the hardly decomposable substance, and can be returned to the makeup water 24.

FIG. 2 shows a second embodiment of the present invention. First,
Exhaust gas 20 discharged from an incinerator or the like is used as a bag filter 10
After separating the fly ash, the exhaust gas from which the fly ash has been removed is sprayed with makeup water 24 containing activated carbon 30 in the scrubber 11 to remove the acid gas, hardly decomposable substances and heavy metals in the exhaust gas. , The scrubber drain 25 is sent to the crusher 13 described later. In the present embodiment, slaked lime is not supplied before the bag filter 10, but slaked lime having a ratio of about 2 equivalents or less at which no slaked lime remains in the fly ash may be supplied as in the first embodiment. The scrubber 11 may be provided in a plurality of stages depending on the concentration of harmful substances in the exhaust gas.

Then, the fly ash 22 separated and collected from the exhaust gas is added with the acid 31 in the fly ash mixing tank 12 and then introduced into the crusher 13. In the crusher 13, the scrubber drainage 2
5 and the fly ash are mixed and stirred to form a slurry, and the slurry is crushed and oxidatively decomposed in the decomposition tank 14 in the presence of hydroxy radicals as in the first embodiment. In the second embodiment, since the fly ash is slurried and pulverized, the surface area of the fly ash becomes large, the contact area with the hydroxy radicals increases, and the reaction is further promoted. In addition, in the second example and the third to seventh examples shown below, description of the same components as those of the first embodiment will be omitted.

In the third embodiment shown in FIG. 3, the fly ash 22 separated and collected from the exhaust gas 20 by the bag filter 10 is mixed with acid in the fly ash mixing tank 12 and then the scrubber drainage is discharged. 25 is mixed in the crushing / decomposing tank 17 introduced into a slurry, and while the slurry is crushed, the hardly decomposable substance contained in the slurry is decomposed and rendered harmless in the presence of hydroxy radicals. The crushing / decomposing tank 17 has substantially the same structure as the crusher of the second embodiment.

In the fourth embodiment shown in FIG. 4, the fly ash 22 collected by the bag filter 10 is guided to the crushing / mixing machine 18,
The acid 31 is added by the crushing / mixing machine 18 and crushed while mixing. The crusher / mixer 18 may have a structure similar to that of the crusher of the second embodiment. Further, the fly ash atomized by the crushing / mixing machine 18 is introduced into the decomposition tank 14 and mixed with the scrubber wastewater 25 to form a slurry, and the hardly decomposable substance contained in the slurry is hydroxy radicals. It is decomposed and made harmless underneath. By configuring as in the third and fourth embodiments,
The hardly decomposable substance can be made harmless with a high decomposition rate, and at the same time, mixing-pulverization or pulverization-decomposition can be performed at the same time, which enables space saving and energy saving.

The fifth to seventh embodiments shown in FIGS. 5 to 7 are devices which do not have a bag filter. In the fifth embodiment of FIG. 5, first, the exhaust gas 20 discharged from the incinerator is scrubbered. The scrubber 11 is sprayed with make-up water 24 charged with activated carbon 30 to separate fly ash in the exhaust gas and to remove acidic gas such as hydrogen chloride, and at the same time, a hardly decomposable substance adsorbed on the activated carbon. And fly ash are separated and collected. Then, the scrubber drainage 25 containing the collected fly ash and the hardly decomposable substance is guided to the decomposition tank 14, and the decomposition tank 1
At 4, the substance is oxidatively decomposed in the presence of hydroxy radicals generated by hydrogen peroxide 26 and ozone 28 to render the hardly decomposed substance and the hardly decomposed substance contained in the fly ash harmless.

According to this method, since the dust is removed from the exhaust gas, the acid gas is removed, and the hardly decomposable substance is removed only by the scrubber 11 without using a bag filter, fly ash can be collected by a dry method. Therefore, it is possible to prevent the persistent pollutant from being contaminated by fly ash and dust scattering. Furthermore, since no bag filter, mixing tank, etc. are provided, space and energy can be saved and efficient processing can be performed.

The sixth embodiment shown in FIG. 6 has substantially the same construction as that of the fifth embodiment, but a crushing / decomposing tank 17 is provided instead of the decomposing tank 14 and the crushing is carried out. In the decomposition tank 17, the fly ash contained in the scrubber wastewater 25 is crushed and oxidatively decomposed in the presence of the hydroxy radicals. Thereby, the decomposition efficiency of the hardly decomposable substance is improved, and the oxidative decomposition reaction can be carried out in a short time.

In the seventh embodiment shown in FIG. 7, after the fly ash and the hardly decomposable substances in the exhaust gas are separated and collected by the scrubber 11, the scrubber wastewater 25 is introduced into the crusher 13, The fly ash contained in the scrubber wastewater 25 is crushed by the crusher 13 and introduced into the decomposition tank 14, where the hard-decomposable substance contained in the fly ash is stirred with strong stirring in the presence of hydroxy radicals. It is oxidatively decomposed and rendered harmless. In addition, it is preferable to supply a surfactant on the upstream side of the decomposition tank 14, whereby the rate of dissolution of the tar component in the fly ash in water is improved and the decomposition is promoted. As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant and the like can be used, and specifically, carboxylate, sulfate ester salt, ethylene glycol, polyhydric alcohol and the like can be used. Can be mentioned. According to such an apparatus, since the pulverization process is sufficiently performed and then the oxidative decomposition process is performed, the decomposition reaction can be performed with high efficiency.

[0035]

As described above, according to the present invention, an adsorbent is added to the makeup water of the scrubber and the mixture is sprayed to remove hardly decomposable substances such as dioxins and heavy metals together with the acidic gas. Therefore, harmful substances in the exhaust gas can be simultaneously treated with a high removal rate. Further, the scrubber wastewater containing the harmful substance is mixed with the fly ash separated from the exhaust gas to be slurried and subjected to the oxidative decomposition treatment, whereby the wastewater treatment equipment need not be separately provided and the treatment can be efficiently performed.

Further, by not introducing a fly ash separating means such as a bag filter and directly introducing the exhaust gas into the scrubber, it is possible to prevent the persistent ash and dust from scattering the hardly decomposable substance, thereby saving energy and space. Can be realized. Furthermore, in such an invention, the alkaline agent is not sprayed on the fly ash-containing exhaust gas, or the amount can be reduced compared to the conventional amount of alkali supplied, and thereby the amount of acid added when precipitating a hardly decomposable substance is reduced. Therefore, the drug cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hardly decomposable substance processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a second example which is another embodiment of FIG.

FIG. 3 is a schematic configuration diagram of a third example which is another embodiment of FIG.

FIG. 4 is a schematic configuration diagram of a fourth example which is another embodiment of FIG.

5 is a schematic configuration diagram of a fifth example which is another embodiment of FIG.

FIG. 6 is a schematic configuration diagram of a sixth example which is another embodiment of FIG.

FIG. 7 is a schematic configuration diagram of a seventh example which is another embodiment of FIG.

FIG. 8 is a schematic configuration diagram showing a conventional apparatus for treating a persistent substance.

FIG. 9 is a schematic configuration diagram showing a conventional treatment device for a hardly decomposable substance.

[Explanation of symbols]

10 Bug filter 11 scrubber 12 Fly ash mixing tank 14 Decomposition tank 17 Crushing / decomposing tank 18 Crusher / Mixer 21 slaked lime 22 Fly ash 24 Make-up water 25 scrubber drainage 26 Hydrogen peroxide 27 drainage 28 Ozone 30 activated carbon 31 acid

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[Procedure amendment]

[Submission date] January 11, 2002 (2002.1.1
1)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Method and apparatus for treating exhaust gas harmful substances

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 11/06 B09B 3/00 304G (72) Inventor Yusuke Kawasaki 1-chome, 1-chome, Sachiura, Kanazawa-ku, Yokohama 1 Mitsubishi Heavy Industry Co., Ltd. Yokohama Research Laboratory (72) Inventor Kimito Kose 1-8-1, Koura, Kanazawa-ku, Yokohama City Mitsubishi Heavy Industries, Ltd. Yokohama Research Laboratory F-term (reference) 4D002 AA19 AA21 AB01 AC04 AC10 BA03 BA04 BA14 CA01 CA07 DA02 DA05 DA12 DA42 EA02 GA01 GA03 GB06 GB09 HA01 4D004 AA37 AB06 AB07 CA04 CA15 CA36 CA43 CB13 CC01 CC11 CC12 4D059 AA30 BC10 BJ01 BK11 BK23 DA43 DA44 DA45

Claims (10)

[Claims] 1. A method of treating harmful substances including hardly decomposable substances such as dioxins from exhaust gas discharged from a combustion device such as a boiler, a melting furnace, an incinerator, and guiding the exhaust gas to the scrubber. A method for treating harmful substances in exhaust gas, comprising spraying water containing an adsorbent for hardly decomposable substances to remove harmful substances such as acidic gas and hardly decomposable substances in the exhaust gas. 2. The fly ash is separated from the exhaust gas on the upstream side of the scrubber, an acid is added to the separated fly ash, and the fly ash in an acidic state is mixed with the waste water discharged from the scrubber. 2. The method for treating harmful substances in exhaust gas according to claim 1, wherein the slurry is slurried, and the slurry is oxidatively decomposed in the presence of hydroxy radicals to render the hardly decomposable substance contained in the slurry harmless. 3. The method for treating harmful substances in exhaust gas according to claim 2, wherein the slurry is pulverized before the oxidative decomposition or simultaneously with the oxidative decomposition. 4. The method for treating harmful substances in exhaust gas according to claim 1, wherein an alkaline agent is supplied to the fly ash-containing exhaust gas to remove the acidic gas in the exhaust gas, wherein the fly ash has a pH concentration of about pH 8. A method for treating harmful substances in exhaust gas, wherein the supply amount of the alkaline agent is set as follows. 5. The method for treating harmful substances in exhaust gas according to claim 1 or 2, wherein an alkaline agent is supplied to the fly ash-containing exhaust gas to remove the acidic gas in the exhaust gas. A method for treating harmful substances, characterized by having a ratio of 2 equivalents or less. 6. A means for separating fly ash from exhaust gas discharged from a combustion device such as a boiler, a melting furnace, an incinerator, and a scrubber for removing harmful substances such as acid gas from the exhaust gas from which the fly ash has been separated. In the harmful substance treating apparatus, means for adding an acid to the fly ash collected by the fly ash separating means and mixing, means for supplying scrubber wastewater to the fly ash to form a slurry and vigorously stirring the slurry. And a means for oxidatively decomposing a hardly decomposable substance such as dioxins contained in the above in the presence of a hydroxy radical, and the scrubber introducing a hardly decomposable substance adsorbent into the scrubber make-up water. The adsorbent separates and collects the hardly decomposable substance in the exhaust gas, and the oxidative decomposition means decomposes and harmlessly decomposes the hardly decomposed substance at the same time as fly ash. Quality processing equipment. 7. A toxic substance treating apparatus comprising a scrubber for removing toxic substances such as acid gas from exhaust gas discharged from a combustion device such as a boiler, a melting furnace, an incinerator, and the fly ash separated and collected by the scrubber. And a means for oxidatively decomposing hardly-decomposable substances such as dioxins contained in the slurry in the presence of hydroxy radicals, and the scrubber hardly decomposes into makeup water for the scrubber. A means for introducing an adsorbent for a persistent substance, the adsorbent separates and collects a hardly decomposable substance in the exhaust gas, and the oxidative decomposition means decomposing and detoxifying the hardly decomposed substance at the same time as fly ash. A device for treating harmful substances in exhaust gas, which is characterized in that 8. The exhaust gas harmful substance treating apparatus according to claim 6, further comprising means for crushing the fly ash upstream of the decomposing means. 9. The harmful substance treating apparatus according to claim 6, further comprising means for supplying an alkaline agent to the fly ash-containing exhaust gas, wherein the alkaline agent is adjusted so that the fly ash has a pH concentration of about 8 or less. An exhaust gas toxic substance treatment device characterized by setting the supply amount of the exhaust gas. 10. The harmful substance treating apparatus according to claim 6, further comprising means for supplying an alkali agent to the fly ash-containing exhaust gas, wherein the alkali agent supplying means supplies an alkali agent having a ratio of about 2 equivalents or less. An exhaust gas toxic substance treatment device characterized by being supplied.