JP2003112012A - Method and apparatus for removing dioxins in exhaust gas from waste treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for removing dioxins in exhaust gas of a waste treatment furnace in which the emission concentration of dioxins is reduced to a lower level. SOLUTION: After exhaust gas discharged from a waste treatment furnace is cooled, dust is collected by a bag filter 1, and dioxins in the exhaust gas after dust are oxidatively decomposed by a catalytic reaction in a catalyst layer 3a, and further mist-like. The dioxins are adsorbed in the downstream by the adsorption layer 4a to remove dioxins in the exhaust gas from the waste treatment furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing dioxins from exhaust gas of a waste treatment furnace for removing dioxins from exhaust gas discharged from the waste treatment furnace of a waste treatment facility.

[0002]

2. Description of the Related Art A catalytic reaction tower is used as a removal device for removing dioxins from exhaust gas discharged from a waste treatment furnace of a waste treatment facility. For example, Japanese Patent No. 2633
In Japanese Patent No. 316, as shown in the flow chart of the conventional exhaust gas treatment of FIG. 3, the combustion exhaust gas generated in the incinerator 11 is cooled by the gas cooling tower 12 and the air preheater 13 and collected by the dust collector 14. After that, the titanium oxide carrier is introduced into a catalytic reactor 15 in which a catalyst supporting vanadium pentoxide and tungsten trioxide is packed, and toxic aromatic chlorine compounds (dioxins) are oxidatively decomposed to be harmless, A method for treating exhaust gas of a waste incinerator that is discharged from a chimney 17 by a blower 16 is described.

[0003]

In the catalytic reaction of the catalytic reaction tower, gaseous dioxins are oxidatively decomposed, but mist-like (particulate) dioxins trapped in oil or the like cannot be decomposed. . 0.01 for dioxins
At a concentration level of ngTEQ / m ³ N or less, the proportion of mist-like dioxins was relatively large, and there was a limit to the emission concentration of dioxins in the catalytic reaction.

Adsorption and removal are effective for removing mist-like dioxins, but in the case of adsorption and removal, dioxins are not decomposed but only accumulated in the adsorbent, so that the adsorbent is constantly replaced. Had to make layers.

There is also a process of adding an adsorbent such as activated carbon to adsorb and remove dioxin before introducing the exhaust gas into the bag filter. Requires heat treatment.

Therefore, the present invention provides a method and an apparatus for removing dioxins in exhaust gas of a waste treatment furnace, which makes the emission concentration of dioxins lower.

[0007]

The method for removing dioxins in exhaust gas of a waste treatment furnace according to the present invention is a method for cooling exhaust gas discharged from a waste treatment furnace, then collecting it with a bag filter, and collecting dust with a bag filter. It is characterized in that dioxins in exhaust gas are oxidatively decomposed by a catalytic reaction, and mist-like dioxins are adsorbed and removed by an adsorbent in a downstream flow.

Further, the apparatus for removing dioxins in exhaust gas of a waste treatment furnace of the present invention cools the exhaust gas discharged from the waste treatment furnace, collects it with a bag filter, and dioxins in the exhaust gas after collection. In a dioxin removing device for removing gases, (1) a catalytic reaction device having a catalyst layer for oxidizing and decomposing dioxin in exhaust gas is provided downstream of a dust collector,
Further, an adsorber having an adsorption layer for adsorbing mist-like dioxins in exhaust gas is connected to the downstream of the catalytic reactor (2) Dioxins in exhaust gas are oxidatively decomposed to the downstream of the dust collector A catalyst reaction / adsorption device is provided in which a catalyst layer is formed and an adsorption layer for adsorbing mist-like dioxins is formed in one can body in the downstream of the catalyst layer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The mist-like dioxins are those trapped in solids, liquids, oils, etc., and remain on the filter paper when the dioxin concentration is measured.

In the present invention, the catalyst is used in a conventional catalytic reaction apparatus of an exhaust gas apparatus, and for example, the catalyst in which vanadium pentoxide and tungsten trioxide are supported on the titanium oxide carrier is used. Activated carbon or activated coke is used as an adsorbent in the adsorption layer of the adsorption device or the catalytic reaction / adsorption device.

The catalyst having a higher temperature and the catalyst having a lower temperature are advantageous in removing dioxins, respectively, but the operating temperature according to the present invention is preferably 150 to 230 ° C, and preferably 170 to 200 ° C. The characteristics of can be fully exhibited. Before introducing the exhaust gas into the corrosion medium reactor, N
Denitration may be performed simultaneously by blowing H ₃ .

[0012]

EXAMPLE 1 FIG. 1 is a flow chart showing an example of a method for removing dioxins in exhaust gas according to the present invention.

The high-temperature exhaust gas discharged from a waste treatment furnace such as a waste incinerator or a waste melting furnace is cooled to a working temperature (170 ° C.) of the bag filter 1 and a reaction aid (slaked lime). ) Is added to neutralize and is introduced into the bag filter 1 to collect dust.

The exhaust gas discharged from the bag filter 1 is
The blower 2 introduces the catalyst layer 3a into the catalytic reaction device 3 and oxidatively decomposes gaseous dioxins in the exhaust gas by catalytic reaction.

The exhaust gas discharged from the catalytic reaction device 3 is
It is introduced into the adsorption device 4 in which the adsorption layer 4a made of an adsorbent is formed, and the mist-like dioxins that cannot be oxidized and decomposed in the catalytic reaction device 3 are adsorbed and removed. The exhaust gas discharged from the adsorption device 4 is discharged from the chimney.

Example 2 FIG. 2 is a flow chart showing another example of the method for removing dioxins in exhaust gas according to the present invention.

As in Example 1, the exhaust gas discharged from the bag filter 1 is introduced into the catalytic reaction / adsorption device 5 by the blower 2. In this example, the exhaust gas was subjected to catalytic reaction.
A heating device 6 is installed between the bag filter 1 and the catalytic reaction / adsorption device 5 in order to heat it to a temperature that accelerates the catalytic reaction before introducing it into the adsorption device 5.

In the catalytic reaction / adsorption device 5, a catalyst layer 5a for oxidatively decomposing dioxins in exhaust gas is formed in one can body, and an adsorption layer 5b is incorporated in the downstream of the catalyst layer 5a. In the catalytic reaction / adsorption device 5, the catalyst layer 5
In a, the gaseous dioxins in the exhaust gas are oxidatively decomposed by the catalytic reaction, and then the mist-like dioxins which have not been oxidatively decomposed in the catalyst layer 5a are adsorbed and removed in the downstream adsorption layer 5b.

Table 1 shows the dioxin concentration of each example, and the comparative example is an example in which only the catalytic reaction device is installed downstream of the bag filter.

Each of the examples is an example of melting treatment in a waste melting furnace. High-temperature exhaust gas discharged from the waste melting furnace is burned in a combustion chamber and recovered in heat by a hot water generator, and an exhaust gas temperature controller is provided. The temperature is lowered to 170 ° C. at a temperature of 70 ° C., the temperature is lowered to the operating temperature of the bag filter, the bag filter is neutralized with slaked lime, collected with the bag filter, and introduced into the catalytic reaction tower.

[0021]

[Table 1] As is clear from Table 1, mist-like dioxins that cannot be oxidatively decomposed by catalytic reaction can be adsorbed and removed by the adsorption layer, and the emission concentration of dioxins in the exhaust gas can be made extremely low.

[0022]

According to the present invention, the catalytic reaction device and the adsorption device are installed in series in the downstream of the dust collector, or the last flow part of the existing catalytic reaction device is replaced with an adsorption layer to form a catalytic reaction / adsorption device. Since the mist-like dioxins that cannot be decomposed by the catalyst can be adsorbed and removed by the adsorption layer, the emission concentration of dioxins in the exhaust gas can be made extremely low.

Further, according to the present invention, the amount of adsorbent used can be reduced and the time to breakthrough can be extended by disposing the adsorption layer after decomposing dioxins into carbon dioxide and hydrogen chloride with a catalyst. The adsorption tower equipment can be made compact.

Further, the catalyst layer and the adsorption layer are integrated with the can to form a catalytic reaction / adsorption device, which can be used as a simple facility, and the duct length can be shortened to reduce the dioxins extremely low. It is possible to prevent synthesis at the concentration level.

[Brief description of drawings]

FIG. 1 is a flow chart of a method for removing dioxins in exhaust gas according to the present invention.

FIG. 2 is a flow chart of another embodiment of the method for removing dioxins in exhaust gas according to the present invention.

FIG. 3 is a flow chart of conventional exhaust gas treatment.

[Explanation of symbols]

1: Bug filter 2: Blower 3: Catalytic reaction device 4: Adsorption device 5: Catalytic reaction / adsorption device 5a: catalyst layer 5b: Adsorption layer 11: Incinerator 12: Gas cooling tower 13: Air preheater 14: Dust collector 15: catalytic reactor 16: Blower 17: Chimney

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Kobayashi             46-59 Nakahara, Tobata-ku, Kitakyushu City Made in Japan             Engineering Co., Ltd. (72) Inventor Masakazu Higuchi             46-59 Nakahara, Tobata-ku, Kitakyushu             Into Design Co., Ltd. F-term (reference) 4D002 AA21 AC04 BA04 BA05 BA13                       BA14 BA16 CA07 DA41 DA70                       EA01 EA02 EA03 GA01 GB03                 4D048 AA11 AB01 AB03 CD01 CD03                       CD04 CD08 DA03 DA06                 4G066 AA04 AA05 BA09 CA33 DA02

Claims (5)

[Claims] 1. After cooling the exhaust gas discharged from the waste treatment furnace, it is collected by a dust collector, and the dioxins in the exhaust gas after dust collection are oxidatively decomposed by a catalytic reaction, and further in a mist form in the downstream. A method for removing dioxins in exhaust gas from a waste treatment furnace, which comprises adsorbing and removing the dioxins of the above with an adsorbent. 2. The method for removing dioxins from exhaust gas in a waste treatment furnace according to claim 1, wherein the exhaust gas temperature is 150 to 230 ° C. 3. A dioxin-removing device that cools exhaust gas discharged from a waste treatment furnace, collects it with a bag filter, and removes dioxins from the exhaust gas after collecting dust, in a downstream flow of the dust collector. A catalytic reaction device with a catalyst layer that oxidatively decomposes dioxins in exhaust gas is formed in the adsorption reactor, and an adsorption layer that adsorbs mist-like dioxins in exhaust gas is formed in the downstream of the catalytic reaction device. A device for removing dioxins from exhaust gas of a waste treatment furnace, which is characterized by connecting the device. 4. A dioxin-removing device that cools exhaust gas discharged from a waste treatment furnace, collects it with a dust collector, and removes dioxins in the exhaust gas after dust collection. A catalytic reaction / adsorption device in which a catalyst layer that oxidatively decomposes dioxins in exhaust gas is formed in the flow and an adsorption layer that adsorbs mist-like dioxins is formed in one can body in the downstream of the catalyst layer. A device for removing dioxins from exhaust gas in a waste treatment furnace, which is characterized by being provided. 5. The apparatus for removing dioxins in exhaust gas of a waste treatment furnace according to claim 3 or 4, wherein the adsorbent used in the adsorption layer is activated carbon or activated coke.