JP2000325734A - Apparatus and method for decomposing harmful substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject apparatus and method for individually or simultaneously detoxifying a halogenated aromatic compd. such as dioxins or the like, nitrogen oxide, sulfur oxide, a volatile org. compd. or the like contained in exhaust gas discharged from an urban refuse incinerator or the like. SOLUTION: First and second electrodes 11, (12), a potential difference imparting means 15 for imparting potential difference across the first and second electrodes 11, (12) and a harmful substance adsorbing material 14 arranged between the first and second electrodes 11, (12) are provided. By imparting potential difference across the first and second electrodes, the harmful substance adsorbed on the adsorbing material 14 is decomposed on the surface of the adsorbing material and in the vicinity thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various incinerators such as municipal waste incinerators, industrial waste incinerators, sludge incinerators, etc.
It relates to technology for purifying harmful substances such as exhaust gas emitted from pyrolysis furnaces, melting furnaces, and various industries such as food manufacturing and chemical manufacturing industries, and exhaust gas generated from vehicles, etc., particularly contained in exhaust gas. Halogenated aromatic compounds such as dioxins, highly condensed aromatic hydrocarbons, environmental hormones, nitrogen oxides, sulfur oxides, volatile organic compounds, etc.
Also, the present invention relates to an apparatus and a method for decomposing harmful substances for detoxification.

[0002]

BACKGROUND ART For example NO _X, VOC (volatile organic compounds, Volatile Organic Compound), harmful substances such as ethylene, a method in particular for decomposing toxic gas or the like, a method of performing plasma processing is known. Hereinafter, a conventional gas plasma processing method will be described.

FIG. 9 is a block diagram of a conventional gas decomposition apparatus. As shown in FIG. 9, in the conventional gas decomposition apparatus, a linear electrode 02 is provided at the center of a cylindrical vessel 01, and the vessel 01 is grounded and used as a negative electrode. The linear electrode 02 is a positive electrode and is connected to a high-voltage pulse power supply 03.

In the case of decomposing harmful substances in a gas by the gas decomposer, for example, an exhaust gas 06 discharged from an engine 04 flows into a vessel 01 through a pipe 05 (arrow D), and a voltage is applied to the linear electrode 02. To the container 0
By giving a potential difference between 1 and the linear electrode 02,
The harmful substances are decomposed by plasma treatment of the exhaust gas 06 by plasma discharge.

[0005] This plasma decomposition proceeds by the following reaction. That is, the moisture (H ₂ O) in the exhaust gas,
Nitrogen (N ₂ ) and oxygen (O ₂ ) are ionized and radicalized (activated) by the following reaction formulas (1) to (3) by plasma treatment. Where:
The symbol * indicates a radicalized product.

H ₂ O + e → H * + OH * + e (1) N ₂ + e → 2N * + e (2) O ₂ + e → 2O * + e (3) Here, the above reaction formulas (1) to (3) H generated in
*, 2N *, and O * are a hydrogen radical, a nitrogen radical, and an oxygen radical, respectively, and are chemically unstable because they are radicalized (activated). Therefore, the oxygen radical (O *) reacts with NO, which is a harmful substance in the exhaust gas, as shown in the following reaction formula (4), and chemically stable NO ₂
Generate NO + O * → NO ₂ (4) Next, NO ₂ reacts with OH * as shown in the following reaction formula (5). NO ₂ + OH * → HNO ₃ (5)

As described above, in the conventional plasma processing,
As shown in the reaction formula (5), nitric acid (HNO ₃ ) is produced as a by-product. Therefore, this nitric acid is then neutralized by adding NH ₃ (ammonia) to make it into powdery nitrate,
Had been disposed of.

[0008]

The above conventional plasma processing method has the following problems. The first problem is that since the exhaust gas to be treated is subjected to plasma processing while flowing in the container 01, the concentration does not increase when the exhaust gas concentration in the container 1 is low. Therefore, since the exhaust gas having a low concentration of harmful substances is subjected to the plasma treatment, the reactions of the reaction formulas (4) and (5) are difficult to proceed sufficiently, and the amount of decomposition of the exhaust gas is small accordingly. The first problem is a problem that occurs when the exhaust gas is processed while continuously flowing in the container 01.

Second, nitric acid (HNO ₃ ) is generated as a by-product when NOx is decomposed, and a neutralizing agent (NH ₃ ) is added to the nitric acid to produce nitric acid. Since the processing has to be performed, the number of processing steps is large and time-consuming, and the processing cost is increased. The second problem is a problem caused by performing the plasma processing in the air, that is, in the oxygen atmosphere.

Accordingly, an object of the present invention is to provide an adsorbent for plasma treatment capable of efficiently performing plasma treatment of a harmful substance, and an apparatus and a method for decomposing harmful substances using the adsorbent.

[0011]

According to a first aspect of the present invention, there is provided a first electrode and a second electrode, and a potential difference between the first electrode and the second electrode. Potential difference applying means, and an adsorbent disposed between the first electrode and the second electrode for adsorbing harmful substances, and applying a potential difference between the first electrode and the second electrode. Thereby, the harmful substance adsorbed by the adsorbent is decomposed on the adsorbent surface and in the vicinity thereof.

According to a second aspect of the present invention, there is provided a first electrode, a second electrode, potential difference applying means for applying a potential difference between the first electrode and the second electrode, and the first electrode. And the second
An adsorbent disposed between the first and second electrodes for adsorbing harmful substances, and applying a potential difference between the first electrode and the second electrode to reduce the harmful substances adsorbed on the adsorbent. It is characterized in that it decomposes on the surface of the adsorbent in the atmosphere and its vicinity.

According to a third aspect of the present invention, in the second aspect, a container for accommodating the adsorbent is provided, and reducing gas supply means for supplying a reducing gas is provided in the container.

According to a fourth aspect of the present invention, there is provided a first electrode, a second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and the first electrode. And the second
A plurality of decomposition units, each of which is composed of an adsorbent that adsorbs harmful substances and is disposed between the electrodes, and a gas supply unit that supplies exhaust gas to the adsorbent of each decomposition unit and discharges gas from the adsorbent. Gas discharging means is provided.

According to a fifth aspect of the present invention, in the fourth aspect, a container for accommodating the adsorbent is provided, and reducing gas supply means for supplying a reducing gas is provided in the container.

[0016] According to a sixth aspect of the present invention, in the first, second or fourth aspect, a pressure reducing means for reducing the pressure in the container for storing the adsorbent is provided, and the plasma treatment is performed while desorbing harmful substances from the adsorbent. It is characterized by.

According to a seventh aspect of the present invention, in the sixth aspect, a pressure reducing means for reducing the pressure inside the container for storing the adsorbent, and a plasma processing chamber for introducing harmful substances desorbed from the adsorbent by the pressure reducing means. And a harmful substance is plasma-treated in the treatment chamber.

[0018] The invention of claim 8 is characterized in that, in claim 1, 2, or 4, a photocatalyst is dispersed in a container containing the adsorbent.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the harmful substance is exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, or the like. .

[0020] In the invention of claim 10, in claim 9, the harmful substance in the exhaust gas is selected from dioxins, polyhalogenated biphenyls, halogenated benzenes, halogenated phenols and halogenated toluenes. It is characterized in that it is at least one halogenated aromatic compound, a highly condensed aromatic hydrocarbon, and an environmental hormone.

The invention of claim 11 is characterized in that, in claim 9, the harmful substance in the exhaust gas is nitrogen oxide.

[0022] The invention of claim 12 is an exhaust gas treatment apparatus for purifying exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, or the like, comprising: a dust removal apparatus for removing dust in the exhaust gas; 11. The harmful substance decomposing apparatus according to claim 1, which is provided on a downstream side of the apparatus.

According to a thirteenth aspect of the present invention, the exhaust gas is supplied to the adsorbent disposed between the first electrode and the second electrode to cause the adsorbent to adsorb harmful substances in the exhaust gas, By applying a potential difference between the first electrode and the second electrode by the potential difference applying means in that state, the harmful substances adsorbed by the adsorbent are decomposed on the surface of the adsorbent and in the vicinity thereof in a reducing atmosphere. And

According to a fourteenth aspect, in the thirteenth aspect, the decomposition is performed by supplying a reducing gas to the adsorbent from a reducing gas supply means.

According to a fifteenth aspect of the present invention, there is provided a first electrode, a second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and a first electrode. A plurality of decomposition units each of which is provided between the first electrode and the second electrode, and an adsorbent that adsorbs harmful substances, and a gas supply unit that supplies exhaust gas to the adsorbent of each decomposition unit; A gas decomposition method using a gas decomposition device provided with gas discharge means for discharging gas, wherein exhaust gas is supplied to an adsorbent of each decomposition unit to decompose harmful substances adsorbed by each adsorbent. It is characterized by doing.

[0026] The invention of claim 16 is characterized in that the decomposition is performed by supplying a reducing gas to the adsorbent from a reducing gas supply means.

[0027] The invention of claim 17 is characterized in that, in claim 13 or 15, plasma decomposition is performed while desorbing harmful substances from the adsorbent.

[0028] The invention of claim 18 is characterized in that, in claim 13 or 15, the harmful substance is desorbed from the adsorbent, introduced into another container and concentrated, and the plasma is decomposed in the container. I do.

[0029]

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

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. In FIG. 1, reference numeral 10 denotes a gas decomposition unit, and a container 13 is disposed between a first electrode 11 and a second electrode 12 in a plate shape. The container 13 is made of an insulating material such as glass, and contains an adsorbent 14 therein. The adsorbent 14 is large adsorption capacity of the NO _X contained the like in the exhaust gas of a gasoline engine. At this time, the shape of the electrode is not limited to the plate shape, but may of course include a wire-to-flat plate, a wire-to-cylinder, and the like.

The adsorbent 14 is not particularly limited as long as it has a property of adsorbing and holding harmful substances. For example, when adsorbing ethylene gas (food storage), Na-X is used. MEK (methyl ethyl ketone)
For adsorbing high silica zeolite, USY, ZS
Using M-5, pentasil type zeolite, Cu-ZSM ₅ or the like used in the case of adsorbing NOx, using a mesoporous silicate when adsorbing dioxins, V
When OC (volatile organic compound) is adsorbed, high silica zeolite, USY, ZSM-5 is used, and when dichloroethylene is adsorbed, Na-Y or the like can be used.

The first electrode 11 is a plasma electrode,
A power supply 15 such as a high-voltage AC power supply or a pulse power supply is connected as a potential difference applying means. The second electrode 12 is a negative electrode and is connected to the ground 16.
When an AC power supply is used as the power supply 15, the adsorbent 14 particularly has a ferroelectric substance. A first pipe 21 is connected to one surface of the container 13, and a second pipe 22 is connected to the other surface. The first pipe 21 has a first valve 2 as an opening / closing means for opening and closing the first pipe 21.
3 is provided, and the second pipe 22 is provided with a second valve 24 as opening and closing means for opening and closing the second pipe 22. The first pipe 21 and the first valve 23 are the container 1
3 constitutes a gas supply means for supplying gas to the adsorbent 14 in the second pipe 3 and the second pipe 22 and the second valve 24.
Are gas discharging means for discharging gas from the adsorbent 14 in the container 13.

A third pipe 25 is connected to the container 13. The third pipe 25 is provided with a third valve 26 as opening and closing means for opening and closing the third pipe 25. The third pipe 25 is connected to a reducing gas supply means 27 such as a nitrogen gas cylinder, and supplies a reducing gas such as nitrogen gas into the container 13 through the third pipe 25. It is not always necessary to provide such reducing gas supply means 27. The valves 23, 24, 26 and the like are automatically controlled by control means (not shown) such as a CPU.

This gas decomposing apparatus has the above-described configuration, and its operation will be described below. With the first valve 23 opened, exhaust gas containing NO is supplied from the gasoline engine (not shown) into the container 13 through the first pipe 21 (arrow A), and NO is adsorbed by the adsorbent 14. .
At this time, the second valve 24 of the second pipe 22 is open, and NO-less gas is discharged.

When the NO is sufficiently adsorbed by the adsorbent 14, the first valve 23 is preferably closed to prevent the exhaust gas from being supplied from the first pipe 21 so that the inside of the container 13 is substantially sealed. Then, a voltage is applied to the first electrode 11. Here, since the container 13 is hermetically closed and external air hardly enters from the surface of the adsorbent 14 to the inside, the container 13 is almost in a reducing atmosphere from the surface to the inside of the adsorbent 14. This is because the adsorbent surface also selectively adsorbs gas. In this case, desirably, the third valve 26 is opened and the reducing gas supply means 27 is opened.
By supplying a reducing gas such as nitrogen gas into the container 13 from (arrow C), the inside of the container 13 can be further made into a reducing gas atmosphere.

When a voltage is applied to the first electrode 11, a high potential difference is generated between the first electrode 11 and the second electrode 12, and the following reaction formulas (6) and (7) appear in a reducing atmosphere. The radical reaction shown in (1) occurs. 2NO + 2N * → 2N ₂ + 2O (6) 2O → O ₂ (7) That is, as shown in the above reaction formula (6), NO in the exhaust gas becomes nitrogen gas N ₂ in a reducing atmosphere, and the reaction formula ( The 2O generated in 6) becomes oxygen gas O ₂ as shown in the above reaction formula (7). This nitrogen gas N ₂ and oxygen gas O
₂ is a chemically stable and harmless gas.

When the reactions of the above reaction formulas (6) and (7) occur, the second valve 24 is opened, and the nitrogen gas N ₂ and the oxygen gas O ₂ in the container 13 are discharged to the outside (arrows). B). As described above, harmful NO in exhaust gas from the engine is decomposed into harmless nitrogen gas N ₂ and oxygen gas O ₂ .

This gas decomposition apparatus has the following advantages. First, since the decomposition of the gas is performed in a reducing atmosphere or a substantially reducing atmosphere, the HN is decomposed as in the above-described conventional method.
O ₃ is not generated, so there is no need to add a neutralizing agent such as ammonia to treat it with ammonium nitrate. Second, since the gas is substantially confined by adsorbing the gas onto the adsorbent 14 in the container and a reaction such as a radical reaction is performed as a batch method (ie, the gas is continuously flowed as in the above-described conventional method). Therefore, the gas concentration in the container is increased, and a large amount of gas can be decomposed by efficiently performing a reaction such as a radical reaction. However, it is not prohibited to generate a radical reaction in the container 13 while the first valve 23 and the second valve 24 are kept open. However, in this case, external air enters the container 13 to reduce it. It is desirable to avoid such an operation method because the atmosphere is reduced and the gas concentration in the container 13 is reduced to lower the radical reaction efficiency.

[0039] In the first embodiment that Second Embodiment above, except for the reducing gas supplying means 27 shown in FIG. 1, the adsorbent container 13, carrying a photocatalyst such as TiO ₂ A decomposition device is configured by dispersing a particle (not shown). With such an apparatus, not only the harmful substance is decomposed by the plasma treatment, but also the synergistic effect of decomposing the harmful substance by the oxidative decomposition of the photocatalyst using ultraviolet light generated by the plasma treatment is exhibited. Is done.

That is, in the present invention, harmful substances (for example, N 2) in the exhaust gas introduced into the plasma
O _X) is the following chemical reaction by plasma decomposition described above (8), the decomposition proceeds in (9), as described above, when the photocatalyst is supported on the spacer 104, the following chemical reaction by photocatalytic degradation The decomposition of (10) and (11) proceeds. Further, the generated reaction product such as nitric acid is excited and desorbed by the collision of plasma, and can be rendered harmless by adding NH ₃ on the downstream side to form ammonium nitrate. Note that although nitrogen oxides (NO _X) and as an example to explain the mechanism of degradation as hazardous substances, as described below, decomposition targets of the present invention is not limited any way.

<Decomposition by Plasma> NO + O → NO ₂ (8) NO ₂ + OH → HNO ₃ (9) <Decomposition by Photocatalyst> NO + O → NO ₂ (10) NO ₂ + OH → HNO ₃ (11)

The photocatalyst is not particularly limited as long as it is a commonly used photocatalyst. For example, titanium oxide (TiO ₂ ), zinc oxide (ZnO), iron oxide (F
e ₂ O ₃ ), tin oxide (SnO ₂ ), tungsten oxide (WO), and bismuth oxide (BiO ₃ ), but the present invention is not limited thereto. Any photocatalyst may be used as long as it causes decomposition. Of the above photocatalysts, titanium oxide is particularly preferable, and anatase type TiO ₂ and rutile type Ti
Any of O ₂ may be used.

Here, the harmful substances in the exhaust gas to be decomposed in the present invention include nitrogen oxides, dioxins and PCs.
Hazardous substances such as harmful aromatic compounds represented by Class B, harmful substances such as aromatic hydrocarbons with a high degree of condensation, and gaseous organic compounds, are harmful in exhaust gas that can be decomposed by the plasma decomposition and photocatalytic decomposition of the present invention. Substance (or environmental hormone)
However, it is not limited to these.

Here, the above dioxins are a general term for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).
It is said to be generated in trace amounts during the combustion of chlorine compounds and certain organic chlorine compounds, and is a chemically colorless crystal. There are 75 types of PCDDs and 135 types of PCDFs depending on the number of chlorines, from dichloride to octachloride. Of these, dibenzo-p-dioxin tetrachloride (T ₄ CDD) is the most common. It is known to be highly 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.) and must be removed from the exhaust gas. The dioxins include not only chlorinated aromatic compounds but also halogenated dioxins such as Br-dioxins.

PCBs (polychlorinated biphenyls)
Is a generic term for compounds in which several chlorine atoms are added to biphenyl, and there are isomers depending on the number of chlorine substitutions and substitution positions.
Typical are 2,6-dichlorobiphenyl, 2,2'-dichlorobiphenyl, 2,3,5-trichlorobiphenyl, etc., which are highly toxic and may generate dioxins when incinerated. Known as
It must be removed from the exhaust gas. In addition, coplanar P
CB is also included.

A high degree of condensation aromatic hydrocarbon is a general term for polynuclear aromatic compounds, which may contain one or more OH groups, is recognized as a carcinogen, and needs to be removed from exhaust gas. .

In many cases, exhaust gas containing gaseous organic compounds such as formaldehyde, benzene or phenol in addition to dust may be generated. These organic compounds are also environmental pollutants and significantly impair human health and need to be removed from the exhaust gas.

The nitrogen oxide to be treated in the present invention usually means NO and NO ₂ , and a mixture thereof.
It is also called NOx. However, the NOx often contains nitrogen oxides having various oxidation numbers and being unstable in addition to the above. Accordingly, x is not particularly limited, but is usually a value of 1 to 2. It becomes nitric acid, nitrous acid, etc. in rainwater or NO, or NO is said to be one of the main causes of photochemical smog, and is a harmful compound to the human body.

VOC (volatile organic compound)
It is particularly generated in chemical factories, printing factories, coating factories, etc., and includes, for example, hydrocarbons such as benzene, toluene, xylene, methane, butane, hexane, and cyclohexane, lower alcohols such as methanol and isopropanol, acetone, methyl ethyl ketone ( Examples include ketones such as MEK), organic acids such as formic acid and acetic acid, aldehydes such as formaldehyde and acetaldehyde, chlorofluoromethane, halocarbons such as chloromethane, dichloromethane, trichloroethane and trichloroethylene, ethyl acetate, butyl acetate, and ammonia. However, the present invention is not limited to this.

That is, the above-mentioned harmful substance is concentrated by the adsorbent by plasma treatment in a container in which the particle-size-supporting photocatalyst according to the present invention and the adsorbent are dispersed. Harmful substances and gaseous organic compounds such as nitrogen oxides, dioxins, and highly condensed aromatic hydrocarbons can be detoxified by plasma decomposition and oxidative decomposition.

Here, the principle of plasma decomposition of dioxins is not clear at present, but an example of the decomposition mechanism will be described with reference to the following "Chemical Formula 1". Physical collisions of high-energy electrons in the plasma dissociate the tail bonds of dioxins or break the benzene ring. Also, high-energy electrons collide with dioxins, and the impact decomposes ether bonds and benzene rings. Further, it is presumed that water and N ₂ in the exhaust gas are decomposed by plasma discharge to generate N *, O *, and OH *, which are decomposed by these radicals.

[0052]

Embedded image

[Third Embodiment] Next, an application example of the gas decomposition apparatus shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a configuration diagram showing a combination of a plurality of gas decomposition apparatuses according to the first embodiment of the present invention. As shown in FIG.
Two gas decomposition units 10A and 10B are provided in parallel, and the first pipe 21 is connected to the engine 28. The same elements as those in FIG. 1 are denoted by the same reference numerals. The apparatus shown in FIG. 2 includes two disassembly units 10 shown in FIG.
These are combined in parallel.

Next, the operation will be described. As shown in FIG.
Since this gas decomposing device is provided with two decomposing units 10A and 10B, it is desirable that the two gas decomposing units 10A and 10B alternately decompose the gas described above.
That is, when the first valve 23 on one decomposition unit 10A side is closed and the switch S1 is closed to supply a voltage to cause a radical reaction or the like in the decomposition unit 10A, the second valve 23 on the other decomposition unit 10B side is generated. One valve 23
Is opened, and the switch S2 is opened to supply exhaust gas from the engine 28 to the decomposition unit 10B. When the radical reaction or the like of one of the decomposition units 10A is completed and nitrogen gas N ₂ and oxygen gas O ₂ are discharged from the second pipe 22, or when the next exhaust gas is supplied from the engine 28 to the decomposition unit 10A , The switch S1 is opened, the switch S2 is closed, and the disassembly unit 1
A voltage is applied to the first electrode 11 of OB to generate a radical reaction.

If the two decomposition units are provided and the two decomposition units sequentially or alternately decompose the gas, the resolution rate can be significantly increased.
Of course, also in this case, preferably, the reducing gas is supplied from the reducing gas supply means 27 to each of the decomposition units. Of course, the radical reaction may be performed in parallel by the two decomposition units, and the operation method can be freely determined. In addition, three or more disassembly units may be provided, and in this case, the above-described processing can be performed alternately or sequentially in each disassembly unit, and further arbitrarily in parallel. As the type of the adsorbent, one having good adsorbability of the gas is selected and used according to the type of the gas to be decomposed.

[Fourth Embodiment] FIG. 3 shows a fourth embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. This disassembly unit 10C also includes a first electrode 11C and a second electrode 12C.
C, a container 13C is disposed between the two adsorbents 14A, 14B, 14C.
Is stored. These adsorbents 14A, 14B, 1
4C has different adsorption characteristics, and adsorbs different gases well. These adsorbents 14A, 14B, and 14C may be mixed, but the interior of the container 13C is partitioned by the air-permeable partition 29 as in the present embodiment, and the first chamber is provided in each partitioned chamber.
Adsorbent 14A, second adsorbent 14B, third adsorbent 1
It is desirable to store 4C separately from the viewpoint of handling management. The same elements as those in the above embodiments are denoted by the same reference numerals.

In this embodiment, the first adsorbent 14A is made of NO _X
The second adsorbent 14B is a VOC adsorbent, and the third adsorbent 14C is an adsorbent of another arbitrary gas. The plasma processing method of the present embodiment is the same as that of the first embodiment, but as described above, a plurality of types of adsorbents 14A and 14A are used.
By providing B and 14C, plasma processing of a mixed gas in which a plurality of types of gases are mixed can be performed at a time. Of course, a plurality of the decomposition units shown in FIG. 1 may be connected in series by a pipe or the like to perform the decomposition of the composite gas at a time. As described above, various design changes can be made to the disposition specifications and the structure of the disassembly unit and the adsorbent.

In the above configuration, a potential difference is applied between the first electrode and the second electrode in a state where the gas to be decomposed is adsorbed on the adsorbent, and the gas is decomposed by performing a plasma treatment. In this case, when the O ₂ concentration is originally low, external air hardly enters the inside and the surface of the adsorbent.
The inner surface of the adsorbent is almost kept in a reducing atmosphere containing little oxygen, and the gas is decomposed in this reducing atmosphere state. Thus, for example, if the gas is a low O ₂ gas, such as the exhaust gas of a gasoline engine, the gas will be exclusively decomposed into harmless N ₂ and O ₂ in a reducing atmosphere. In addition, dioxin, VO
C, ethylene and the like have a high O ₂ , and when there is a relatively large amount of O ₂ near the surface of the adsorbent, H ₂ O, CO ₂ and H
It can be converted to Cl or the like.

Further, a gas is sent to the adsorbent, the gas adsorbed on the adsorbent is subjected to plasma treatment to decompose the gas, and the decomposed gas is discharged from the adsorbent. If the treatment is performed, batch-type plasma treatment becomes possible, and the gas concentration can be increased as compared with the conventional plasma treatment performed while continuously flowing the gas, so that the amount of decomposition of the gas is increased accordingly. And efficient decomposition processing can be performed.

[Fifth Embodiment] FIG. 4 shows a fifth embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. The decomposition unit 10D includes a vacuum pump (for example, up to 1 torr, 1/760 atmospheric pressure) as a pressure reducing means having a valve 31 which can be opened and closed in a container 14 in which the adsorbent 13 is stored.
2 are provided. With the vacuum pump 32, the adsorbent 1
The harmful substances adsorbed in 3 can be desorbed by decompression,
When desorbed from the adsorbent, it is instantaneously decomposed by plasma decomposition. The apparatus of the present embodiment is particularly effective when the harmful substances adsorbed on the surface or inside of the adsorbent by the plasma cannot be directly decomposed in a state where the harmful substances are adsorbed. In FIG. 4, a pulse power supply is used as a power supply, for example, a pulse power supply having a pulse width of 100 ns or less and a voltage of 20 kV or more is used. However, in the present invention, the type of power supply for generating plasma is not particularly limited. . In addition,
At this time, when the harmful substance to be decomposed by the plasma is nitrogen or the like, the reducing gas supply means shown in FIG. 1 may be provided in order to provide a reducing atmosphere.

[Sixth Embodiment] FIG. 5 shows a sixth embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. In the sixth embodiment, the decomposing apparatuses of the fifth embodiment are arranged in parallel, and decompose harmful substances adsorbed on an adsorbent in a batch system. In FIG. 5, two gas decomposition units 10E and 10F are provided in parallel, and the first pipes 21A and 21B are connected to exhaust gas introduction means. The same elements as those in FIG. 4 are denoted by the same reference numerals. Here, in FIG. 5, the gas decomposition unit 10E
In this state, the exhaust gas is supplied to the exhaust gas and the harmful substances are adsorbed by the adsorbent 14, the valves 21A, 24A, 31B are closed, and the other valves 21B, 24B, 31A are open. When the inside of the container 13 of the decomposition unit 10E is decompressed by the vacuum pump 32 in such a state,
The harmful substances adsorbed inside the adsorbent are desorbed and decomposed by the plasma treatment. The harmful substances that are not decomposed by the plasma treatment are adsorbed by the adsorbent 14 in the container 13 of the decomposition unit 10F that adsorbs the harmful substances in the other exhaust gas, and are not discharged to the outside. By repeatedly performing such operations repeatedly, the decomposition of the exhaust gas can be efficiently treated. At this time, if the harmful substance to be decomposed by the plasma is nitrogen or the like, the reducing gas supply means shown in FIG. 1 may be provided in order to provide a reducing atmosphere.

[Seventh Embodiment] FIG. 6 shows a seventh embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. This decomposition unit 10G is a vacuum pump (for example, up to 1 torr, 1/760 atmospheric pressure) as a pressure reducing means provided with a valve 31 which can be opened and closed in a container 14 in which an adsorbent 13 is stored.
2 and a plasma processing chamber 33 for separately concentrating harmful substances desorbed by the decompression means. According to this apparatus, the harmful substances adsorbed by the adsorbent 13 are decompressed and desorbed by the vacuum pump 32, and the desorbed harmful substances are concentrated in the plasma processing chamber 33 to perform plasma treatment in a high concentration state. be able to. The plasma processing chamber 33 is provided with an electrode having a plate shape, a line-to-plate, a line-to-cylinder, and the like, and a power source such as a high-voltage AC power source or a pulse power source is connected as a plasma electrode as a potential difference applying means. I have. Thereby, the container 1 containing the adsorbent is
In addition to decomposing when desorbing from the adsorbent in 3, the harmful substances concentrated in the concentration vessel can be separately decomposed. Therefore, when the harmful substance adsorbed on the surface / inside of the adsorbent is hardly decomposed directly in the adsorbed state, the plasma decomposition treatment can be performed efficiently.

[Eighth Embodiment] FIG. 7 shows an eighth embodiment of the present invention.
It is a lineblock diagram of a gas decomposition device of an embodiment. In the eighth embodiment, the decomposition units of the seventh embodiment are arranged in parallel, and the harmful substances adsorbed on the adsorbent in a batch system are separately concentrated and decomposed. In FIG. 7, two gas decomposition units 10H and 10I are provided in parallel, and the first pipes 21A and 21B are connected to exhaust gas introduction means. The same elements as those in FIG. 6 are denoted by the same reference numerals. Here, in FIG. 7, the exhaust gas is supplied to the gas decomposition unit 10H, and the harmful substances are adsorbed by the adsorbent, and the valves 21A, 24A,
31B is closed, and the other valves 21B, 24B,
31A is open. When the pressure inside the container 13 of the decomposition unit 10H is reduced by the vacuum pump 32 in such a state, the harmful substances adsorbed in the adsorbent are desorbed and decomposed by the plasma treatment. At this time, undecomposed harmful substances are concentrated in a plasma processing chamber 33 as a concentration means, and then subjected to plasma processing. The harmful substances that are not decomposed by the plasma treatment are adsorbed by the adsorbent 14 in the container 13 of the decomposition unit 10I that adsorbs harmful substances in other exhaust gas, and are not discharged to the outside. Thereby, it can be decomposed when desorbed from the adsorbent in the container 13 in which the adsorbent is stored, and the harmful substances concentrated in the plasma processing chamber 33 can be separately decomposed. Therefore, when the harmful substance adsorbed on the surface / inside of the adsorbent is hardly decomposed directly in the adsorbed state, the plasma decomposition treatment can be performed efficiently.

[Ninth Embodiment] Next, a case where the decomposition apparatus of the present invention is applied to the treatment of exhaust gas from an incinerator will be described.

FIG. 8 shows a schematic example of an exhaust gas purifying apparatus using the above harmful substance decomposing apparatus, but the apparatus of the present invention is not limited to this.

As shown in FIG. 8, an exhaust gas treatment apparatus according to the present embodiment comprises a cooling device 52 provided on the downstream side of various incinerators 51 for incinerating various kinds of refuse such as municipal waste, industrial waste and sludge. And a bag filter 53 provided on the downstream side of the cooling device 52 for collecting dust, and the decomposition device 10 shown in FIGS. 1 to 7 for treating the exhaust gas after the dust collection. . As a result, the high-temperature exhaust gas from the incinerator is cooled and then dust-removed, and thereafter, the harmful substances in the exhaust gas are decomposed in the decomposer 110, and the exhaust gas obtained by decomposing and removing the harmful substances is discharged from the chimney 55 to the outside. I try to discharge. As a result, harmful substances such as dioxins and nitrogen oxides in the exhaust gas are decomposed, and the purified exhaust gas can be discharged from the chimney.

[0067]

As described above, according to the present invention,
According to the first aspect of the present invention, the first electrode and the second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and the first electrode An adsorbent disposed between the second electrodes to adsorb harmful substances,
By applying a potential difference between the first electrode and the second electrode, the harmful substances adsorbed by the adsorbent are decomposed on the adsorbent surface and in the vicinity thereof. It is possible to raise the gas concentration in a substantially closed state by adsorbing it, and to generate a radical reaction or the like in that state. it can.

According to the second aspect of the invention, the first electrode and the second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, An adsorbent that is disposed between the first and second electrodes and adsorbs harmful substances, and is applied to the adsorbent by applying a potential difference between the first and second electrodes. Harmful substances are decomposed in the reducing atmosphere on the surface of the adsorbent and in the vicinity thereof, so that the gas can be decomposed in the reducing atmosphere. And the like can be generated, so that the gas decomposing ability can be remarkably enhanced to perform efficient gas decomposition.

According to the third aspect of the present invention, since the container for accommodating the adsorbent is provided and the reducing gas supply means for supplying the reducing gas is provided in the container, efficient decomposition in a reducing atmosphere is provided. Can be.

According to the invention of claim 4, the first electrode and the second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and the first electrode Gas supply means for supplying exhaust gas to the adsorbent of each decomposition unit, comprising a plurality of decomposition units each comprising an adsorbent for adsorbing harmful substances and disposed between the first electrode and the second electrode; Since the gas discharging means for discharging the gas from the material is provided, the resolution ratio can be remarkably increased if the gas is decomposed sequentially or alternately by a plurality of decomposition units.

According to the fifth aspect of the present invention, since the container for accommodating the adsorbent is provided and the reducing gas supply means for supplying the reducing gas is provided in the container, efficient decomposition in the reducing atmosphere is provided. Can be.

According to the sixth aspect of the present invention, since the decompression means for decompressing the inside of the container accommodating the adsorbent is provided and the plasma treatment is performed while desorbing the harmful substance from the adsorbent, the harmful substances adsorbed by the adsorbent are removed. The substance can be desorbed under reduced pressure, and when desorbed from the adsorbent, it can be instantaneously decomposed by plasma decomposition.

According to the invention of claim 7, there is provided a pressure reducing means for reducing the pressure in the container storing the adsorbent, and a plasma processing chamber for introducing harmful substances desorbed from the adsorbent by the pressure reducing means. Since the harmful substance is subjected to the plasma treatment in the treatment chamber, the harmful substance adsorbed in the adsorbent is desorbed and decomposed by the plasma treatment in a state where the harmful substance is concentrated in the treatment chamber, thereby improving the decomposition efficiency.

According to the eighth aspect of the present invention, since the photocatalyst is dispersed in the container containing the adsorbent, a synergistic effect is obtained by decomposition by the photocatalyst together with plasma decomposition.

According to the ninth aspect of the present invention, the harmful substance can efficiently decompose exhaust gas discharged from an incinerator, a thermal decomposition furnace, a melting furnace, or the like.

According to the invention of claim 10, the harmful substance in the exhaust gas is at least one selected from dioxins, polyhalogenated biphenyls, halogenated benzenes, halogenated phenols and halogenated toluenes. Can degrade halogenated aromatic compounds, highly condensed aromatic hydrocarbons and environmental hormones.

According to the eleventh aspect, the nitrogen oxides in the exhaust gas can be efficiently decomposed because the decomposition is performed in a reducing atmosphere.

According to the invention of claim 12, the incinerator,
An exhaust gas treatment device for purifying exhaust gas discharged from a pyrolysis furnace, a melting furnace, etc., comprising a dust removal device for removing dust in the exhaust gas, and a harmful substance decomposition device provided downstream of the dust removal device. Therefore, harmful substances in the exhaust gas can be efficiently decomposed.

According to the thirteenth aspect of the present invention, the exhaust gas is supplied to the adsorbent disposed between the first electrode and the second electrode so that the adsorbent adsorbs harmful substances in the exhaust gas. In this state, by applying a potential difference between the first electrode and the second electrode by the potential difference applying means, the harmful substances adsorbed by the adsorbent are decomposed on the surface of the adsorbent and in the vicinity thereof in a reducing atmosphere. The gas can be decomposed in a reducing atmosphere, and it is possible to raise the gas concentration in a substantially sealed state and generate a radical reaction or the like in that state. Higher and more efficient gas decomposition can be performed.

According to the fourteenth aspect, since the reducing gas is supplied from the reducing gas supply means to the adsorbent to perform the decomposition, the decomposition can be efficiently performed in a reducing atmosphere.

According to the invention of claim 15, the first electrode and the second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, Gas supply means for supplying exhaust gas to the adsorbent of each decomposition unit, comprising a plurality of decomposition units each comprising an adsorbent for adsorbing harmful substances and disposed between the first electrode and the second electrode; A method for decomposing a gas by a gas decomposer provided with a gas discharge means for discharging gas from a material, wherein exhaust gas is supplied to an adsorbent of each decomposition unit and harmful substances adsorbed by each adsorbent are provided. Since the gas is decomposed, if a plurality of decomposition units sequentially or alternately decompose the gas, the resolution rate can be significantly increased.

According to the sixteenth aspect of the present invention, since the reducing gas is supplied from the reducing gas supply means to the adsorbent to perform the decomposition, efficient decomposition can be performed in a reducing atmosphere.

According to the invention of [claim 17], claim 1
In 3 or 15, since the plasma decomposition is performed while desorbing the harmful substance from the adsorbent, it is possible to instantaneously decompose by the plasma decomposition when desorbing from the adsorbent.

According to the invention of claim 18, claim 1
At 3 or 15, the harmful substances are desorbed from the adsorbent, introduced into another container and concentrated, and the plasma is decomposed in the container. Therefore, the harmful substances adsorbed inside the adsorbent are desorbed and treated in the processing chamber. In the state in which the harmful substances are concentrated, the harmful substances are separately decomposed by plasma treatment, and the decomposition efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a gas decomposition apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a gas decomposition apparatus according to a third embodiment of the present invention.

FIG. 3 is a configuration diagram of a gas decomposition apparatus according to a fourth embodiment of the present invention.

FIG. 4 is a configuration diagram of a gas decomposition apparatus according to a fifth embodiment of the present invention.

FIG. 5 is a configuration diagram of a gas decomposition apparatus according to a sixth embodiment of the present invention.

FIG. 6 is a configuration diagram of a gas decomposition apparatus according to a seventh embodiment of the present invention.

FIG. 7 is a configuration diagram of a gas decomposition apparatus according to an eighth embodiment of the present invention.

FIG. 8 is a configuration diagram of a gas decomposition apparatus according to a ninth embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional gas decomposition apparatus.

[Explanation of symbols]

 Reference Signs List 10 Gas decomposition unit 11 First electrode 12 Second electrode 13 Container 14, 14A, 14B, 14C Adsorbent 15 Power supply 21 First pipe 22 Second pipe 23 First valve 24 Second valve 25 First 3 pipe 26 third valve 27 reducing gas supply means 31 valve 32 vacuum pump 33 plasma processing chamber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akinori Yasutake 5-717-1 Fukahori-cho, Nagasaki-shi, Nagasaki Sanishi Heavy Industries Co., Ltd. No. 717-1 F-term in Nagasaki Laboratory, Mitsubishi Heavy Industries, Ltd. (Reference) 2E191 BA12 BB00 BD18 4D012 CA12 CB01 CF03

Claims (18)

[Claims] A first electrode, a second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and a potential difference applying means for applying a potential difference between the first electrode and the second electrode. An adsorbent that is disposed on the adsorbent and adsorbs harmful substances, and by applying a potential difference between the first electrode and the second electrode, the harmful substances adsorbed by the adsorbent are adsorbed on the adsorbent surface and the adsorbent. An apparatus for decomposing harmful substances, which decomposes in the vicinity. 2. A first electrode and a second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and a potential difference applying means between the first electrode and the second electrode. An adsorbent disposed on the adsorbent for adsorbing harmful substances, and applying a potential difference between the first electrode and the second electrode so that the harmful substances adsorbed on the adsorbent are adsorbed in a reducing atmosphere. An apparatus for decomposing harmful substances, which decomposes on and near the surface. 3. The harmful substance decomposition apparatus according to claim 2, further comprising: a container for storing the adsorbent; and a reducing gas supply unit for supplying a reducing gas into the container. 4. A first electrode and a second electrode, a potential difference applying means for applying a potential difference between the first electrode and the second electrode, and a potential difference applying means between the first electrode and the second electrode. Gas supply means for supplying exhaust gas to the adsorbent of each decomposition unit, and gas exhaust means for discharging gas from the adsorbent, the plurality of decomposition units being provided in the adsorbent and adsorbing the harmful substances. An apparatus for decomposing harmful substances, comprising: 5. The apparatus for decomposing harmful substances according to claim 4, wherein a container for storing the adsorbent is provided, and reducing gas supply means for supplying a reducing gas is provided in the container. 6. The method for removing harmful substances according to claim 1, 2 or 4, further comprising: a decompression means for reducing the pressure inside the container containing the adsorbent, wherein the plasma treatment is performed while desorbing the harmful substances from the adsorbent. Disassembly device. 7. The processing chamber according to claim 6, further comprising: a pressure reducing means for reducing the pressure in the container storing the adsorbent; and a plasma processing chamber for introducing harmful substances desorbed from the adsorbent by the pressure reducing means. An apparatus for decomposing harmful substances, characterized in that harmful substances are subjected to plasma treatment. 8. An apparatus for decomposing harmful substances according to claim 1, wherein a photocatalyst is dispersed in a container containing said adsorbent. 9. The apparatus for decomposing harmful substances according to claim 1, wherein the harmful substances are exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, or the like. 10. The method according to claim 9, wherein the harmful substance in the exhaust gas is at least one halogenated aromatic selected from dioxins, polyhalogenated biphenyls, halogenated benzenes, halogenated phenols and halogenated toluenes. A device for decomposing harmful substances, which is a compound, a highly condensed aromatic hydrocarbon or an environmental hormone. 11. The apparatus for decomposing harmful substances according to claim 9, wherein the harmful substances in the exhaust gas are nitrogen oxides. 12. An exhaust gas treatment device for purifying exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, or the like, comprising: a dust removal device for removing dust in the exhaust gas; and a dust removal device provided downstream of the dust removal device. An exhaust gas treatment apparatus comprising the harmful substance decomposition apparatus according to any one of claims 1 to 10. 13. An exhaust gas is supplied to an adsorbent disposed between a first electrode and a second electrode to cause a harmful substance in the exhaust gas to be adsorbed by the adsorbent, and in this state, a potential difference providing means is used. A method for decomposing harmful substances, characterized in that a harmful substance adsorbed on an adsorbent is decomposed on a surface of the adsorbent and in the vicinity thereof in a reducing atmosphere by applying a potential difference between the first electrode and the second electrode. . 14. The method for decomposing harmful substances according to claim 13, wherein the decomposition is performed by supplying a reducing gas to the adsorbent from a reducing gas supply means. 15. A first electrode and a second electrode, a potential difference providing means for providing a potential difference between the first electrode and the second electrode, and a potential difference providing means between the first electrode and the second electrode. Gas supply means for supplying exhaust gas to the adsorbent of each decomposition unit, and gas exhaust means for discharging gas from the adsorbent, the plurality of decomposition units being provided in the adsorbent and adsorbing the harmful substances. A method for decomposing gas by a gas decomposer provided with: a method of supplying exhaust gas to an adsorbent of each decomposition unit to decompose harmful substances adsorbed by each adsorbent. Decomposition method of the substance. 16. The method for decomposing harmful substances according to claim 15, wherein the decomposition is performed by supplying a reducing gas from the reducing gas supply means to the adsorbent. 17. The method for decomposing harmful substances according to claim 13 or 15, wherein plasma decomposition is performed while desorbing harmful substances from the adsorbent. 18. The method for decomposing a harmful substance according to claim 13 or 15, wherein the harmful substance is desorbed from the adsorbent, introduced into another container, concentrated, and subjected to plasma decomposition in the container.