WO2020241379A1 - Incineration facility - Google Patents

Abstract

An incineration facility is provided with: an incineration furnace (1) for incinerating a waste material; a temperature-decreasing column (2) for decreasing the temperature of an exhaust gas generated as the result of the incineration of the waste material; a bagfilter (3) for removing soot and dust from the exhaust gas of which the temperature has been decreased; a reducing agent injection section (8) for injecting a reducing agent for denitration use into the exhaust gas from which the soot and dust have been removed; and a catalytic reaction column (6) for accelerating the reaction of the exhaust gas with the reducing agent with a catalyst. The reducing agent comprises an alcohol or a hydrocarbon. The catalyst comprises at least one metal which is selected from the group consisting of Ag, Bi and Pb and is supported on a catalyst support comprising MFI-type or FER-type zeolite.

Description

Incineration facility

The present invention relates to an incineration facility that incinerates waste.

Exhaust gas emitted from incineration facilities contains harmful substances such as nitrogen oxides, and it is necessary to remove harmful substances from the exhaust gas before it is released into the atmosphere in order to prevent air pollution. In order to remove nitrogen oxides from exhaust gas, denitration of exhaust gas by reaction with a reducing agent is adopted. As a specific configuration of the incinerator, for example, as described in Japanese Patent Application Laid-Open No. 2003-220317 (hereinafter, Patent Document 1), an incinerator that incinerates waste and an incinerator from this incinerator. It is equipped with a catalytic reaction tower that denitrates exhaust gas.

In the incineration facility described in Patent Document 1, as shown in FIG. 1 of Patent Document 1, the exhaust gas from the incinerator 1 is not denitrated as it is in the catalytic reaction tower 6, but is previously removed from the exhaust gas by the bag filter 3. Soot and dust are removed. Further, a filter cloth for filtering the soot and dust of the exhaust gas is installed in the bag filter 3, and since this filter cloth is damaged by the high temperature exhaust gas, the temperature reducing tower (EC) 2 is located on the upstream side of the bag filter 3. Be prepared.

By the way, in the incineration facility described in Patent Document 1, if the exhaust gas is cooled by the temperature reducing tower (EC) 2, the catalytic activity of the catalyst reaction tower 6 is low due to the low temperature, so a catalyst for supplementing the exhaust gas. Amount is needed. Further, in order to raise the temperature of the exhaust gas to the catalytic reaction tower 6, as shown in FIG. 1 of Patent Document 1, a steam type reheater 5 for heating the exhaust gas is provided on the upstream side of the catalytic reaction tower 6. As described above, the incineration facility has a complicated structure by providing the steam type reheater 5.

And there is also a method of using ammonia as a reducing agent. This method is also called an ammonia selective reduction method, and is a mainstream method for removing nitrogen oxides in exhaust gas. However, in these configurations, in an atmosphere in which the injected ammonia exists, it reacts with the sulfur oxide present in the exhaust gas to generate ammonium sulfate such as acidic ammonium sulfate. Therefore, the accumulation of ammonium sulfate on the catalyst in the catalytic reaction tower 6 lowers the catalytic activity. Further, the generated ammonium sulfate may cause the exhaust gas flow path to be blocked in the equipment downstream of the catalytic reaction tower 6.

Therefore, an object of the present invention is to provide an incineration facility capable of preventing a decrease in catalytic activity and blockage of an exhaust gas flow path with a simple configuration.

In order to solve the above problems, the incinerator according to the first invention includes an incinerator that incinerates waste and an incinerator.
A heating tower that cools the exhaust gas generated by incineration of the waste,
A bug filter that removes soot and dust from the cooled exhaust gas,
A reducing agent injection unit that injects a reducing agent for denitration into the exhaust gas from which soot and dust have been removed,
It is provided with a catalytic reaction tower that promotes the reaction between the exhaust gas and the reducing agent by a catalyst.
The reducing agent is alcohol or hydrocarbon,
The catalyst is a catalyst carrier containing MFI-type or FER-type zeolite on which at least one metal selected from the group consisting of Ag, Bi and Pb is supported.

Further, in the incineration facility according to the second invention, the alcohol as the reducing agent in the incineration facility according to the first invention is methanol or ethanol.

Further, in the incineration facility according to the third invention, the temperature of the exhaust gas is 130 ° C. to 200 ° C. in the catalytic reaction tower of the incineration facility according to the first or second invention.

In addition, the incineration facility according to the fourth invention is the incineration facility according to the first or second invention without a reheating device for reheating the exhaust gas.

According to the incineration facility, it is not necessary to reheat the exhaust gas sent to the catalytic reaction tower, so that the configuration for reheating the exhaust gas required for the conventional incineration facility becomes unnecessary, and as a result, the configuration is simplified. Can be. Further, since the reducing agent of the incineration facility does not generate ammonium sulfate, it is possible to prevent a decrease in catalytic activity and blockage of the exhaust gas flow path due to the production of ammonium sulfate.

It is a schematic block diagram of the incineration facility which concerns on embodiment of this invention.

Hereinafter, the incineration facility according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the incineration facility 10 includes an incinerator 1 for incinerating waste, a temperature reducing tower 2 for reducing the temperature of exhaust gas generated by incineration of the waste, and soot dust from the reduced temperature exhaust gas. It is provided with a bug filter 3 for removing the above. Further, the incineration facility 10 includes a reducing agent injection unit 8 that injects a reducing agent for denitration into the exhaust gas from which soot and dust have been removed, and a catalytic reaction tower 6 that promotes the reaction between the exhaust gas and the reducing agent by a catalyst. To be equipped. Further, the incineration facility 10 may include a chimney 7 that discharges the denitrated exhaust gas into the atmosphere, if necessary.

Here, as the reducing agent, one that does not generate ammonium sulfate such as acidic ammonium sulfate, such as alcohol or hydrocarbon, is adopted. This is because ammonium sulfate may reduce the catalytic activity by accumulating on the catalyst and may cause the exhaust gas flow path to be blocked in the equipment downstream of the catalytic reaction tower 6. As the catalyst, one in which at least one metal selected from the group consisting of Ag, Bi and Pb is supported on a catalyst carrier containing MFI type or FER type zeolite is adopted. This is because the exhaust gas into which the above-mentioned reducing agent (alcohol, hydrocarbon, etc.) that does not generate acidic ammonium sulfate is injected can be sufficiently denitrated even in a low temperature region of about 130 ° C. to 200 ° C. without reheating. .. Therefore, the incineration facility 10 does not need to have a reheater between the bag filter 3 and the catalytic reaction column 6.

The alcohol as the reducing agent is not particularly limited as long as it has a reducing power at the temperature at the time of the reduction treatment of the combustion exhaust gas, but it is preferable to use methanol or ethanol which is an alcohol having a small number of carbon atoms.

An inorganic acid salt (for example, nitrate, chloride, etc.) or an organic acid salt (for example, acetate, etc.) can be used as a precursor compound of a metal supported on zeolite (hereinafter, catalyst metal) as a catalyst. As a method for supporting the catalyst metal, it is sufficient that the denitration performance can be exhibited, and examples thereof include an ion exchange method and an impregnation supporting method. For example, in the ion exchange method, zeolite is suspended in an aqueous solution containing a precursor compound of at least one metal selected from the group consisting of Ag, Bi, and Pb, and the zeolite to which the catalyst metal is bound by ion exchange is obtained. There is a method of taking it out of an aqueous solution, drying it, and then firing it.

The shape of the catalyst can be arbitrarily selected depending on the reactor to be applied and the gas flow conditions, such as granular, pellet-shaped, honeycomb-shaped, and plate-shaped. From the viewpoint of pressure loss, the catalyst is preferably one in which zeolite is supported on a honeycomb structure made of an inorganic fiber sheet (including an inorganic fiber paper). In particular, the inorganic fiber sheet is preferably a glass fiber sheet or a ceramic fiber sheet.

To produce the catalyst using a honeycomb structure made of an inorganic fiber sheet as a base material, for example, in an aqueous solution containing a precursor compound of at least one metal selected from the group consisting of Ag, Bi, and Pb. , Zeolite is suspended, and a base material of a honeycomb structure made of an inorganic fiber sheet is immersed in a catalyst component-containing slurry containing zeolite to which a catalyst metal is bonded by ion exchange, and after taking this out of the slurry, it is dried and 550. Bake below ° C.

The honeycomb (honeycomb) structure refers to an integrated structure composed of a plurality of through holes (cells) partitioned by a partition and through which exhaust gas can flow, and the partition, and has a cross-sectional shape (of the cell) of the through holes. The cross-sectional shape) is not particularly limited, and examples thereof include a circular shape, an arc shape, a square shape, a rectangular shape, and a hexagonal shape.

To immerse the base material of the honeycomb structure in the slurry, a method (A) of immersing the base material of the honeycomb structure in which an inorganic fiber sheet is previously assembled into a honeycomb (honeycomb) structure and a method (A) of immersing the base material of the honeycomb structure There is a method (B) in which the glass fiber sheet, which is a material, is immersed in the sheet state.

In the above method (A), zeolite was suspended in an aqueous solution containing a precursor compound of at least one metal selected from the group consisting of Ag, Bi, and Pb, and the catalyst metal was bonded by ion exchange. A honeycomb-shaped structure base material in which an inorganic fiber sheet is previously assembled into a honeycomb structure is immersed in a catalyst component-containing slurry containing zeolite, and after taking it out from the slurry, the conditions are 100 to 200 ° C. for 1 to 2 hours. After drying in, and further firing at 300 to 550 ° C. for 1 to 4 hours, the honeycomb structure substrate is provided with at least one catalytic metal selected from the group consisting of Ag, Bi, and Pb. A denitration catalyst is produced by binding the carried zeolite. In the case of the above method (A), the inorganic fiber sheet is preferably a glass fiber sheet or a ceramic fiber sheet.

On the other hand, in the above method (B), a honeycomb structure made of a glass fiber sheet is used as a base material, and a precursor compound of at least one metal selected from the group consisting of Ag, Bi, and Pb is contained. A catalyst component-containing slurry containing zeolite to which a catalyst metal is bound by ion exchange is prepared by suspending zeolite in an aqueous solution, and the catalyst component-containing slurry is applied to a glass fiber sheet to obtain a catalyst-containing slurry-coated glass fiber sheet. Then, the catalyst-containing slurry-coated glass fiber sheet was shaped by a corrugated mold and a pressing jig, and the shaped corrugated plate-shaped catalyst-containing slurry-coated glass fiber sheet was placed at 100 to 200 ° C. for 1 to 2 hours. Dry under and peel from the mold, while flat plate-shaped, catalyst-containing slurry-coated fiberglass sheets that are not corrugated are dried at 100-200 ° C. for 1-2 hours and waved. A group consisting of Ag, Bi, and Pb obtained by firing a plate-shaped catalyst-containing slurry-coated glass fiber sheet and a flat plate-shaped catalyst-containing slurry-coated glass fiber sheet at 300 to 550 ° C. for 1 to 4 hours. A catalyst-supported flat glass fiber sheet and a catalyst-supported corrugated glass fiber sheet in which zeolite supporting at least one catalyst metal selected from the above are bonded are formed, and the catalyst-supported flat glass fiber sheet and the catalyst after firing are formed. A denitration catalyst is produced by laminating supported corrugated glass fiber sheets to form a catalyst-supported honeycomb structure.

Hereinafter, a method for purifying exhaust gas in the incineration facility 10 will be described.

As shown in FIG. 1, in incinerator 1, when waste is incinerated, exhaust gas is generated by the incineration. This exhaust gas is sent to the temperature reducing tower 2, where the temperature is reduced to a temperature suitable for the bug filter 3 on the downstream side of the temperature decreasing tower 2. The bug filter 3 removes soot and dust from the exhaust gas from the temperature reducing tower 2. The exhaust gas from the bag filter 3 is injected with a reducing agent (alcohol, hydrocarbon, etc.) that does not generate acidic ammonium sulfate by the reducing agent injector 8 without being reheated. In the catalytic reaction tower 6, a catalyst metal (at least one metal selected from the group consisting of Ag, Bi and Pb) is supported on a catalyst carrier containing MFI-type or FER-type zeolite, and the exhaust gas is combined with the exhaust gas. The reaction with the reducing agent is promoted. By this reaction, nitrogen oxides are removed from the exhaust gas, that is, the exhaust gas is denitrated. The denitrated exhaust gas is released into the atmosphere from the chimney.

As described above, according to the incineration facility 10, it is not necessary to reheat the exhaust gas sent to the catalytic reaction tower 6, so that the reheating device for reheating the exhaust gas required in the conventional incineration facility becomes unnecessary. As a result, the configuration can be simplified. Further, since the reducing agent of the incineration facility 10 does not generate ammonium sulfate (alcohol, hydrocarbon, etc.), it is possible to prevent a decrease in catalytic activity and blockage of the exhaust gas flow path due to the production of ammonium sulfate.

Claims (4)

An incinerator that incinerates waste and
A heating tower that cools the exhaust gas generated by incineration of the waste,
A bug filter that removes soot and dust from the cooled exhaust gas,
A reducing agent injection unit that injects a reducing agent for denitration into the exhaust gas from which soot and dust have been removed,
It is provided with a catalytic reaction tower that promotes the reaction between the exhaust gas and the reducing agent by a catalyst.
The reducing agent is alcohol or hydrocarbon,
An incineration facility characterized in that the catalyst is a catalyst carrier containing MFI-type or FER-type zeolite on which at least one metal selected from the group consisting of Ag, Bi and Pb is supported. The incineration facility according to claim 1, wherein the alcohol as the reducing agent is methanol or ethanol. The incineration facility according to claim 1 or 2, wherein the temperature of the exhaust gas in the catalytic reaction tower is 130 ° C to 200 ° C. The incineration facility according to claim 1 or 2, wherein there is no reheating device for reheating the exhaust gas.

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