JP2005287759A - Dioxin reducing agent and dioxin reducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dioxin reducing agent and a method of reducing dioxin, capable of inexpensively and easily reducing dioxin generated from an incinerator. <P>SOLUTION: The dioxin reducing agent is characterized by comprising a halogenated organic compound decomposing agent and a dioxin generation preventive agent, and the method of reducing dioxin is characterized by blowing the dioxin reducing agent into a flue of the incinerator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dioxin reducing agent and a reducing method. More specifically, the present invention relates to a dioxin reducing agent and reduction method that can easily reduce dioxins generated from an incinerator at low cost.

Dioxins are substances that are unintentionally generated during the synthesis of chemical substances and the combustion process of waste, and their sources are diverse. A wide range of toxic effects such as carcinogenicity, reproductive toxicity, and teratogenicity have been reported. In particular, reproductive toxicity is concerned that even a very low concentration may affect the living body. In addition to the strength of toxicity, it is a hardly decomposable substance, so once produced, it stays in the environment for a long time, and environmental pollution by dioxins has become a major social problem.
Nearly 90% of the generation of dioxins in Japan is caused by incinerators, and it is required to suppress the generation of dioxins from incinerators. Dioxins are known to be generated in the intermediate temperature range when organic substances are burned in the presence of chlorine. Combustion exhaust gas and Attempts have been made to lower the concentration of dioxins at the exit of the flue by improving combustion methods such as cooling incineration dust as quickly as possible. However, only the improvement of the combustion method has a limit to the reduction of the concentration of dioxins.
As a method for easily removing dioxins generated from incinerators, a method in which powdered activated carbon is blown into the exhaust gas and dioxins are adsorbed and then collected with fly ash in a dust collector has been widely used. The method only recovers the generated dioxins as solids and cannot reduce the generated amount itself. For this reason, the development of chemicals, devices, methods and the like for decomposing dioxins and reducing their concentrations is underway.
For example, as a method for decomposing a chlorinated organic compound that is easy to operate and has a low processing cost, the chlorinated organic compound is released from the active oxygen donor substance in the presence of an active oxygen donor substance such as manganese dioxide or a manganese dioxide-containing substance. A method of decomposing a chlorinated organic compound that decomposes with active oxygen has been proposed (Patent Document 1). Also, as a method of decomposing halogenated organic compounds such as dioxins contained in the exhaust gas generated from the incinerator, a step of injecting trivalent or tetravalent Mn oxide into the exhaust gas generated from the combustion furnace for incinerating waste, and injecting However, a method for decomposing a halogenated organic compound in exhaust gas comprising a step of collecting the Mn oxide and a step of recovering a mixture containing the collected Mn oxide has been proposed (Patent Document 2). However, with these methods, it is difficult to sufficiently reduce the dioxin concentration so as to satisfy the regulation value. In addition, when sufficient contact time cannot be obtained, the decomposition becomes insufficient, and it can be converted into a lower molecular halogenated organic compound. Will work.
Dioxins are effective in preventing and removing dioxins, and can be applied even at high temperatures and are highly safe. Methods for preventing the formation of dioxins include carbonates and / or bicarbonates such as sodium and potassium, zeolites, and diatomaceous earth. A production inhibitor for dioxins obtained by mixing an inorganic adsorbent has been proposed (Patent Document 3). In this case, the use of sodium hydrogen carbonate can prevent the formation of dioxins from chlorophenol due to the fixing effect of chlorophenol, which is a direct precursor of dioxins, but it is not sufficient. In addition, sodium hydrogen carbonate powder having a particle size of about several tens of μm suitable for flue blowing has a problem of poor fluidity and is difficult to handle with an ordinary powder feeder.
As a means to enable removal of halogenated aromatic compounds contained in fly ash as well as desalination of exhaust gas, a chemical agent having an oxidation catalytic activity composed of oxides such as manganese and an alkaline reactant such as sodium bicarbonate A desalinizing composition containing selenium is supplied into the exhaust gas at a position upstream from the dust collector of the exhaust gas treatment device, and then fly ash containing a chemical agent having an oxidation catalytic ability is recovered from the dust collector, A fly ash treatment method has been proposed in which heating to 300 ° C. or higher in the presence is followed by rapid cooling to 200 ° C. or lower (Patent Document 4). However, this method requires a separate heating device in order to decompose the halogenated aromatic compound in the fly ash after adding the desalting composition to the exhaust gas and recovering it together with the fly ash. No method for reducing halogenated aromatic compounds in an incinerator flue is shown. Here, the mixing of the metal oxide and the desalting alkali agent has no particular meaning other than simplifying the operation of blowing the two agents into one agent.
Further, even in a low temperature range applied to bag filter exhaust gas, a specific surface area is 100 m ² / g as a remover capable of efficiently oxidizing and removing dioxins contained in gas discharged from an incinerator or the like. A dioxins remover in which a metal salt and / or a metal oxide is supported on β-MnO ₂ as described above has been proposed (Patent Document 5). However, β-MnO ₂ having a large specific surface area is expensive, and if a new catalyst is supported, the manufacturing cost becomes very high.
Therefore, there has been a demand for a halogenated organic compound reducing agent and reduction method that can easily reduce halogenated organic compounds such as dioxins generated from an incinerator at low cost.
JP 2000-202240 A (second page) JP 2000-364829 A (page 2) JP 2002-177737 A (2nd page) JP 2003-117345 A (page 2-4) JP 2000-135432 A (page 2)

  The present invention was made for the purpose of providing a halogenated organic compound reducing agent and reduction method that can easily reduce halogenated organic compounds such as dioxins generated from an incinerator at low cost. is there.

As a result of intensive studies to solve the above problems, the present inventors have found that an excellent dioxin reduction effect can be obtained by simultaneously using a halogenated organic compound decomposing agent and a dioxin formation inhibitor. It was. By using manganese dioxide, which is an oxidation catalyst with an excellent balance between effect and economy, as the halogenated organic compound decomposing agent, and by using sodium bicarbonate, which has the effect of fixing the dioxin precursor, as the dioxin production inhibitor. The present inventors have found that an excellent dioxin reduction effect can be obtained at low cost, and that an excellent effect is expressed by using γ-type manganese dioxide, and the present invention has been completed based on this finding.
That is, the present invention
(1) A dioxin reducing agent characterized by containing a halogenated organic compound decomposing agent and a dioxin production inhibitor;
(2) The dioxin reducing agent according to (1), wherein the halogenated organic compound decomposing agent is a manganese dioxide-containing substance, and the dioxin production inhibitor is sodium hydrogen carbonate.
(3) The dioxin reducing agent according to (2), wherein the manganese dioxide contained in the manganese dioxide-containing substance is γ-type,
(4) The dioxin reducing agent according to (2) or (3), wherein the content of the manganese dioxide-containing substance is 3 to 80% by weight,
(5) The dioxin reducing agent according to any one of (1) to (4), comprising a fluidization accelerator;
(6) The dioxin reducing agent according to any one of (1) to (5), which contains an inorganic adsorbent that adsorbs dioxins or dioxin precursors,
(7) The dioxin reducing agent according to any one of (1) to (6), wherein the ratio of particles having a particle size of 1 μm or less is 30% by weight or less and the average particle size is 1 to 100 μm,
(8) A dioxin reducing method characterized by blowing the dioxin reducing agent according to any one of (1) to (7) into an incinerator flue, and
(9) The method for reducing dioxins according to (8), wherein the gas temperature of the incinerator flue is 300 to 800 ° C.
Is to provide.

  Injecting a dioxin reducing agent of the present invention containing a halogenated organic compound decomposing agent and a dioxin formation inhibitor, particularly a dioxin reducing agent containing a manganese dioxide-containing substance and sodium hydrogen carbonate into the exhaust gas of a combustion furnace. As a result, a synergistic effect is produced between manganese dioxide and sodium hydrogen carbonate, and a significantly higher dioxin reduction effect can be obtained as compared with the case where each is blown into the exhaust gas of the combustion furnace alone.

The halogenated organic compound reducing agent of the present invention contains a halogenated organic compound decomposing agent and a dioxin production inhibitor. In particular, a substance containing a manganese dioxide-containing substance and sodium hydrogen carbonate can be suitably used.
In the present invention, manganese dioxide is a substance having x greater than 1.75 in the composition MnO _x . There is no restriction | limiting in particular in the manganese dioxide used for this invention, For example, electrolytic manganese dioxide, chemical conversion manganese dioxide, manganese dioxide derived from a mineral, the manganese dioxide collect | recovered as battery waste materials, etc. can be mentioned. The manganese dioxide-containing material used in the present invention may be pure manganese dioxide, but many of commercially available electrolytic manganese dioxide, chemical manganese dioxide, mineral-derived manganese dioxide and the like have a MnO ₂ content of 60 to 60. Such a commercial product can be used as the manganese dioxide-containing substance.
There is no restriction | limiting in particular in the transformation of the manganese dioxide used for this invention, For example, (alpha), (beta), (gamma), (delta), (epsilon), (eta) etc. can be mentioned. Among these, γ-type manganese dioxide is particularly suitable because it has a large action of decomposing halogenated organic compounds. γ-type manganese dioxide is produced by electrolyzing an acidic manganese solution on a positive electrode made of titanium, graphite, lead, etc. by electrolyzing a sulfuric acid manganese solution obtained by treating and purifying rhombomanganese, the main component of which is manganese carbonate, with sulfuric acid. It can be produced as manganese. Since β-type manganese dioxide is produced in large quantities for dry batteries, it can be obtained at low cost.
There is no restriction | limiting in particular in the sodium hydrogencarbonate used for this invention, For example, sodium hydrogencarbonate etc. which are prescribed | regulated to JISK8622, Japanese pharmacopoeia, food additive official regulations, cosmetic raw material standards, etc. can be mentioned.

In the present invention, by integrating into a single agent as a reducing agent for halogenated organic compounds containing manganese dioxide-containing substances and sodium hydrogen carbonate, not only a single chemical storage tank and injection facility are required, but also manganese dioxide containing By mixing the substance with sodium bicarbonate, the fluidity of the powder can be improved and handling is facilitated compared to handling sodium bicarbonate alone. That is, sodium bicarbonate powder having an average particle size of about 10 μm suitable for blowing into an incinerator is likely to solidify due to compaction, and depending on the storage environment, there is a risk of solidification due to moisture absorption. By mixing, solidification due to compaction or moisture absorption can be prevented.
In the reducing agent of the present invention, the content of the manganese dioxide-containing substance is preferably 3 to 80% by weight, and more preferably 5 to 50% by weight. If the content of the manganese dioxide-containing substance is less than 3% by weight, the effect of improving the fluidity may not be sufficiently exhibited. When the content of the manganese dioxide-containing substance exceeds 80% by weight, the effect of preventing dihydrogen generation from sodium hydrogen carbonate may not be recognized.
In the present invention, a fluidization accelerator can be contained in the halogenated organic compound reducing agent. The fluidity of the reducing agent can be further improved by adding a fluidization accelerator to the reducing agent containing the manganese dioxide-containing substance and sodium hydrogen carbonate. Examples of the fluidization promoter to be contained include fine zeolite, silica powder, diatomaceous earth, and pearlite. These fluidization accelerators reduce the adhesion between sodium hydrogencarbonate particles to prevent consolidation, and porous materials such as zeolite and silica absorb moisture, thereby absorbing sodium bicarbonate due to moisture absorption. Solidification can also be prevented.

The reducing agent of the present invention can contain an inorganic adsorbent that adsorbs dioxins or dioxin precursors. The inorganic adsorbent used in the present invention is preferably an adsorbent having many pores with a diameter of 2 to 5 nm suitable for adsorption of dioxins or dioxin precursors. Examples of such an inorganic adsorbent include activated carbon, zeolite, alumina, clay mineral, and the like. By including an inorganic adsorbent that adsorbs dioxins or dioxin precursors in the reducing agent, the effect of reducing dioxins in the exhaust gas can be enhanced. As the inorganic adsorbent, activated carbon having a large dioxin adsorption capacity and low cost can be suitably used. However, when the reducing agent of the present invention is blown into a combustion furnace at a temperature of 300 to 800 ° C., there is a risk of ignition. It is preferable to use inorganic adsorbents such as zeolite, alumina, and clay minerals.
In the reducing agent of the present invention, the ratio of particles having a particle size of 1 μm or less is preferably 30% by weight or less, and more preferably 5% by weight or less. Moreover, it is preferable that an average particle diameter is 1-100 micrometers, and it is more preferable that it is 1.2-60 micrometers. Bag filters used in combustion furnaces are said to be able to collect particles with a particle size of less than 1 μm, but manganese dioxide-containing substances with a particle size of less than 1 μm may clog the filter cloth of the bag filter. Or, there is a risk of causing problems such as passing through a filter cloth. Particles having a particle size exceeding 100 μm may settle and become difficult to disperse into the exhaust gas.

In the halogenated organic compound reduction method of the present invention, the reducing agent of the present invention is blown into the incinerator flue. There is no particular limitation on blowing amount of reducing agent, it is preferably, 0.4~1.2g / m ³ (standard state) is 0.2 to 2 g / m ³ (standard state) with respect to the exhaust gas It is more preferable. If the blowing amount of the reducing agent is less than 0.2 g / m ³ (standard state), the dioxins may not be sufficiently reduced. If the blowing amount of the reducing agent exceeds 2 g / m ³ (standard condition), the dust load on the dust collector may become excessive.
Blowing amount of manganese dioxide-containing material is preferably 50 to 400 mg / m ³ (standard state), and more preferably 100 to 300 mg / m ³ (standard state). Blowing amount of sodium bicarbonate is preferably 100 to 800 mg / m ³ (STP), more preferably 200-600 mg / m ³ (standard state). Blowing amount of the inorganic adsorbent is preferably from 30 to 200 mg / m ³ (STP), more preferably 70~150mg / m ³ (standard state). The optimum amount of blowing of these reducing agent components is influenced by the amount of organic matter and acidic components in the exhaust gas, the contact efficiency with the exhaust gas caused by the structure of the exhaust gas flue, etc., so that the incinerator to which the method of the present invention is applied It is preferable to confirm by conducting a test in advance.

In the method of the present invention, the gas temperature of the incinerator flue into which the reducing agent is blown is preferably 300 to 800 ° C, and more preferably 380 to 600 ° C. Since the temperature at which re-synthesis of dioxins is remarkable is about 300 ° C, dioxins are already generated even if the reducing agent is blown after the flue gas temperature drops below 300 ° C. May not develop. When the temperature of the flue gas exceeds 800 ° C., manganese dioxide is self-decomposed and its activity is lowered, and sodium carbonate produced by decomposition of sodium hydrogen carbonate is melted and may adhere to the inner wall. Examples of the place suitable for blowing the reducing agent include a gas cooling chamber immediately after the incinerator and the vicinity of the outlet of the waste heat boiler. When there is a heat exchanger having an exhaust gas temperature of 200 to 400 ° C., it is highly possible that the synthesis of dioxins is active, so it is preferable to blow in at the inlet of the heat exchanger.
In the method of the present invention, the method of blowing the reducing agent into the incinerator flue is not particularly limited, and examples thereof include a method of blowing the reducing agent supplied from a screw feeder or table feeder with air from a compressor or a blower.
In the method of the present invention, when the reducing agent is blown at the same bag filter inlet as that for blowing ordinary powdered slaked lime or powdered activated carbon, the gas temperature is about 180 ° C., the catalytic activity of manganese dioxide is low, and the halogenated organic compound This is not preferable because a sufficient reduction effect is not obtained. However, when addition at a gas temperature of 300 to 800 ° C. is difficult, a certain degree of effect can be expected even by addition at the front stage of the bag filter. The reduction effect of the halogenated organic compound is because manganese dioxide deposited on the primary adhesion layer of the bag filter becomes a catalyst fixing layer, and the contact efficiency with the exhaust gas becomes higher than when the reducing agent is dispersed in the exhaust gas. In addition, although the re-synthesis of dioxins with a bag filter is less than that of a high-temperature upstream flue, the effect is not negligible, so sodium bicarbonate prevents the synthesis of dioxins by fixing the dioxin precursor. Is also effective.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
Electrolytic manganese dioxide mainly composed of γ type on a quartz column with a diameter of 25 mm [Tosoh Corp., for manganese batteries] 0.1 g, sodium hydrogen carbonate [Asahi Glass Co., Ltd., food additive grade] 0.1 g and glass beads [ A mixture of spheres, average particle size 40 μm] 1.8 g was charged and heated to 300 ° C. Air containing 100 ppm (volume ratio) of dichlorobenzene was passed through the column at 160 mL / min. The concentration of dichlorobenzene in the gas flowing out from the column was 1.0 ppm (volume ratio), and the reduction rate of dichlorobenzene was 99%.
Example 2
The same operation as in Example 1 was performed except that chemical manganese dioxide [Chuo Electric Industry Co., Ltd., CMD-1], which is a mixture of β type and γ type, was used instead of electrolytic manganese dioxide mainly composed of γ type. went. The concentration of dichlorobenzene in the gas flowing out from the column was 13 ppm (volume ratio), and the reduction rate of dichlorobenzene was 87%.
Example 3
The same operation as in Example 1 was performed, except that manganese dioxide derived from minerals mainly containing β type [Kinsei Matec Co., Ltd., N] was used instead of electrolytic manganese dioxide mainly containing γ type. The concentration of dichlorobenzene in the gas flowing out from the column was 31 ppm (volume ratio), and the reduction rate of dichlorobenzene was 69%.
The results of Examples 1 to 3 are shown in Table 1.

As seen in Table 1, it can be seen that manganese dioxide mainly composed of γ-type is superior in resolution of halogenated organic compounds compared to β-type.
Example 4
A filtration test was conducted using a bag filter filter cloth made of a glass / polytetrafluoroethylene mixed nonwoven fabric used in an incinerator. FIG. 1 is an explanatory diagram of the differential pressure test apparatus used. A suction pump 3 and a differential pressure gauge 4 were attached to a filter 2 sandwiching a filter cloth 1 having a filtration area of 13.5 cm ² , and an agent 5 made of a mixture of manganese dioxide and sodium hydrogen carbonate was sucked.
A mixture of 0.1 g of chemical manganese dioxide (Chuo Denki Kogyo Co., Ltd., CMD-1) and 0.1 g of sodium bicarbonate [Asahi Glass Co., Ltd., food additive grade] containing no particles with a particle size of 1 μm or less was sucked. At that time, the differential pressure was 1.76 kPa, and no leakage of the agent from the filter cloth occurred.
Example 5
Instead of chemical conversion manganese dioxide containing no particles having a particle size of 1 μm or less, a mineral-derived manganese dioxide whose proportion of particles having a particle size of 1 μm or less is 35% by weight [Kinsei Matec Co., Ltd., N] was used. The same test as in Example 4 was performed. The differential pressure was 2.64 kPa, the agent leaked, and the filter cloth was clogged.
Comparative Example 1
The same test as in Example 4 was performed except that slaked lime (JIS R 9001 industrial special slaked lime) used in an incinerator was used instead of chemical manganese dioxide not containing particles having a particle size of 1 μm or less. The differential pressure was 1.81 kPa, and no agent leakage occurred.
Comparative Example 2
When the same differential pressure test apparatus as in Example 4 was used and only the suction pump was operated without sucking the agent, the differential pressure was 1.51 kPa.
The results of Examples 4-5 and Comparative Examples 1-2 are shown in Table 2.

As can be seen in Table 2, chemical manganese dioxide that does not contain particles with a particle size of 1 μm or less can be collected without any problem using the currently used bag filter as with slaked lime, but with a particle size of 1 μm or less. It can be seen that mineral-derived manganese dioxide having a particle ratio of 35% by weight is difficult to collect.
Example 6
1 part by weight of chemical manganese dioxide [Chuo Electric Industry Co., Ltd., CMD-1] and 99 parts by weight of sodium hydrogen carbonate [Asahi Glass Co., Ltd., food additive grade, average particle size 10 μm] as defined in JIS K 8622 After mixing, the degree of compression, angle of repose, spatula angle, and uniformity were measured using a powder tester [Hosokawa Micron Co., Ltd.], and Carr's fluidity index (RL Carr, Chem. Eng., Vol. 72, 163-168 pages, January 18, 1965 issue). The fluidity index was 47.
Example 7
3 parts by weight of chemical manganese dioxide and 97 parts by weight of sodium bicarbonate were mixed, and the fluidity index was determined in the same manner as in Example 6. The fluidity index was 53.
Example 8
33 parts by weight of chemical manganese dioxide and 67 parts by weight of sodium bicarbonate were mixed, and the fluidity index was determined in the same manner as in Example 6. The fluidity index was 54.
Example 9
50 parts by weight of chemical manganese dioxide and 50 parts by weight of sodium hydrogen carbonate were mixed, and the fluidity index was determined in the same manner as in Example 6. The fluidity index was 54.
Example 10
As in Example 6, 31.4 parts by weight of chemical manganese dioxide, 63.8 parts by weight of sodium hydrogen carbonate, and 4.8 parts by weight of synthetic zeolite [Asahi Glass Co., Ltd., 4A type, average particle size 1.4 μm] were mixed. Thus, the liquidity index was obtained. The fluidity index was 61.
Example 11
31.4 parts by weight of chemical manganese dioxide, 63.8 parts by weight of sodium hydrogen carbonate, and 4.8 parts by weight of fumed silica [Tokuyama Co., Ltd., Leolosil MT-10] were mixed, and the fluidity was the same as in Example 6. The index was determined. The fluidity index was 64.
Comparative Example 3
About sodium hydrogencarbonate [Asahi Glass Co., Ltd., food additive grade], the fluidity index was determined in the same manner as in Example 6. The fluidity index was 42.
Comparative Example 4
For chemical manganese dioxide [Chuo Electric Industry Co., Ltd., CMD-1], the flowability index was determined in the same manner as in Example 6. The fluidity index was 57.
The results of Examples 6 to 11 and Comparative Examples 3 to 4 are shown in Table 3.

As can be seen in Table 3, sodium hydrogen carbonate is not very fluid, but the addition of manganese dioxide improves the fluidity. In particular, when the amount of manganese dioxide is 3% by weight or more, the effect of improving fluidity is remarkable. Further, when synthetic zeolite or fumed silica is blended as a fluidization accelerator in addition to sodium bicarbonate and manganese dioxide, the fluidity is further improved.
Example 12
The halogenated organic compound reducing agent and reducing method of the present invention were applied to an exhaust gas path of a municipal waste incinerator having the treatment process shown in FIG.
A halogenated organic compound reducing agent in which a chemical manganese dioxide having an average particle size of 1.4 μm and sodium bicarbonate having an average particle size of 10 μm are mixed at a weight ratio of 1: 2 is applied to the exhaust gas at the inlet of an air preheater having an exhaust gas temperature of 450 ° C. Then, it was blown in continuously for 2 days so as to be 600 mg / m ³ (standard state), that is, 200 mg / m ³ (standard state) as manganese dioxide and 400 mg / m ³ (standard state) as sodium bicarbonate.
After reducing agent blowing for 2 days, the concentration of dioxins in fly ash collected in the chimney gas and bag filter was measured. The concentration of dioxins in the chimney gas was 0.31 ng-TEQ / m ³ (standard state), and the concentration of dioxins in the fly ash was 1.9 ng-TEQ / g.
Example 13
Halogenation of artificial zeolite synthesized with an average particle size of 1.4 μm, sodium bicarbonate with an average particle size of 10 μm, and artificial zeolite synthesized from coal ash with an average particle size of 3.4 μm in a weight ratio of 1: 2: 0.5. In the same manner as in Example 12, the organic compound reducing agent was 700 mg / m ³ (standard state) with respect to the exhaust gas at the inlet of the air preheater having an exhaust gas temperature of 450 ° C., that is, 200 mg / m ³ (standard state) as manganese dioxide. Then, it was blown in continuously for 2 days so as to be 400 mg / m ³ (standard state) as sodium hydrogen carbonate and 100 mg / m ³ (standard state) as artificial zeolite.
After reducing agent blowing was continued for 2 days, the concentration of dioxins was measured in the same manner as in Example 12. The concentration of dioxins in the chimney gas was 0.18 ng-TEQ / m ³ (standard state), and the concentration of dioxins in the fly ash was 2.1 ng-TEQ / g.
Comparative Example 5
In the same manner as in Example 12, a chemical obtained by mixing an artificial zeolite synthesized from sodium hydrogen carbonate having an average particle diameter of 10 μm and coal ash having an average particle diameter of 3.4 μm at a weight ratio of 500 mg / M ³ (standard state), that is, 400 mg / m ³ (standard state) as sodium hydrogen carbonate and 100 mg / m ³ (standard state) as artificial zeolite were blown continuously for 2 days.
After reducing agent blowing was continued for 2 days, the concentration of dioxins was measured in the same manner as in Example 12. The concentration of the dioxins in the chimney gas was 0.30 ng-TEQ / m ³ (standard state), and the concentration of the dioxins in the fly ash was 3.5 ng-TEQ / g.
Comparative Example 6
Sodium bicarbonate having an average particle size of 10 μm was blown in continuously for 2 days so that the exhaust gas was 400 mg / m ³ (standard state), and the concentration of dioxins was measured in the same manner as in Example 12. The concentration of the dioxins in the chimney gas was 0.45 ng-TEQ / m ³ (standard state), and the concentration of the dioxins in the fly ash was 3.1 ng-TEQ / g.
Comparative Example 7
Chemical manganese dioxide having an average particle size of 1.4 μm was blown in continuously for 2 days so as to be 200 mg / m ³ (standard state) with respect to the exhaust gas, and the concentration of dioxins was measured in the same manner as in Example 12. . The concentration of dioxins in the chimney gas was 0.90 ng-TEQ / m ³ (standard state), and the concentration of dioxins in the fly ash was 2.7 ng-TEQ / g.
Comparative Example 8
The concentration of dioxins in the chimney gas and the concentration of dioxins in fly ash when no chemical was blown into the exhaust gas were measured. The concentration of dioxins in the chimney gas was 0.92 ng-TEQ / m ³ (standard state), and the concentration of dioxins in the fly ash was 3.5 ng-TEQ / g.
The results of Examples 12 to 13 and Comparative Examples 5 to 8 are shown in Table 4.

  As can be seen from Table 4, in Comparative Example 8 where no chemical was blown into the exhaust gas, in Example 12 where the halogenated organic compound reducing agent of the present invention containing manganese dioxide and sodium hydrogen carbonate was blown, The concentration of dioxins in the chimney gas is reduced to about one third, and the dioxin concentration of fly ash is reduced to about one half. In Example 13 in which a reducing agent containing manganese dioxide, sodium hydrogen carbonate and artificial zeolite was blown, the concentration of dioxins in the chimney gas was further reduced. On the other hand, in Comparative Example 5 in which sodium hydrogen carbonate and artificial zeolite were blown in, Comparative Example 6 in which only sodium hydrogen carbonate was blown in, and Comparative Example 7 in which only manganese dioxide was blown in, the degree of decrease in the concentration of dioxins was small. .

  The concentration of dioxins is reduced by bringing the dioxins reducing agent containing the halogenated organic compound decomposing agent and dioxin formation inhibitor of the present invention into contact with exhaust gas or fly ash containing dioxins. can do. As a dioxin reducing agent of the present invention, by synthesizing a manganese dioxide-containing substance and sodium bicarbonate into the exhaust gas of the combustion furnace, a synergistic effect is developed between manganese dioxide and sodium bicarbonate, Compared with the case where the gas is blown into the exhaust gas of the combustion furnace alone, a significantly higher dioxin reduction effect can be obtained, and the combustion furnace can be operated safely.

It is explanatory drawing of the differential pressure test apparatus used in the Example. It is a treatment process figure of a municipal waste incinerator.

Explanation of symbols

1 Filter cloth 2 Filter 3 Suction pump 4 Differential pressure gauge 5 Agent

Claims (9)

  A dioxin reducing agent comprising a halogenated organic compound decomposing agent and a dioxin production inhibitor.   The dioxin reducing agent according to claim 1, wherein the halogenated organic compound decomposing agent is a manganese dioxide-containing substance, and the dioxin production inhibitor is sodium hydrogen carbonate.   The dioxin reducing agent according to claim 2, wherein the manganese dioxide contained in the manganese dioxide-containing substance is γ-type.   The dioxin reducing agent according to claim 2 or 3, wherein the content of the manganese dioxide-containing substance is 3 to 80% by weight.   The dioxin reducing agent according to any one of claims 1 to 4, comprising a fluidization accelerator.   The dioxin reducing agent according to any one of claims 1 to 5, comprising an inorganic adsorbent that adsorbs dioxins or dioxin precursors.   The dioxin reducing agent according to any one of claims 1 to 6, wherein the ratio of particles having a particle size of 1 µm or less is 30 wt% or less and the average particle size is 1 to 100 µm.   A method for reducing dioxins comprising blowing the dioxin reducing agent according to any one of claims 1 to 7 into an incinerator flue.   The method for reducing dioxins according to claim 8, wherein the gas temperature of the incinerator flue is 300 to 800 ° C.

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