JP2000189754A - Removing device of harmful material in waste gas, its method and activated carbon for removing harmful material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a harmful material removing device and a harmful material removing method capable of increasing the removing efficiency of the harmful material such as dioxins. SOLUTION: In the waste gas treating device provided with the adsorption column for adsorbing the harmful material such as dioxins in waste combustion waste gas and the desalting device for removing the acidic gas. such as gaseous hydrogen chloride in the waste gas, the adsorption column is disposed at the upstream side of the desalting device, and the device is operated so that the inside of the adsorption column may be a gaseous hydrogen chloride atmosphere. The inside of the column is kept in gaseous hydrogen chloride or gaseous chlorine atmosphere by injecting the gaseous hydrogen chloride or the gaseous chlorine into the adsorption column for adsorbing the harmful material such as dioxins in the waste combustion waste gas. The temp. at the inside of the adsorption column is kept at 100-200 deg.C and the concn. of the gaseous hydrogen chloride or the gaseous chlorine is kept at 1-100 ppm (dry) preferably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for removing harmful substances typified by dioxins (hereinafter abbreviated as DXN) in waste combustion exhaust gas,
Further, the present invention relates to activated carbon used in the method.

[0002]

2. Description of the Related Art As a method for removing harmful substances such as DXN generated in a waste incinerator, a method using an adsorbent has been proposed. Among the adsorbents, the most promising one for removing DXN is activated carbon.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a harmful substance removing apparatus and a harmful substance removing method which can enhance the efficiency of removing harmful substances such as DXN. An object of the present invention is to provide an adsorbent that can increase the efficiency of removing harmful substances.

[0004]

According to the present invention, there is provided an apparatus for removing harmful substances from exhaust gas, comprising: an adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas; In an exhaust gas treatment device provided with a desalination device for removing acidic gas components, an adsorption tower is provided upstream of the desalination device, and the operation is performed so that the inside of the adsorption tower becomes a hydrogen chloride gas atmosphere. It is assumed that.

A method for removing harmful substances from exhaust gas according to the present invention comprises the steps of: injecting hydrogen chloride gas or chlorine gas into an adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas; Is a hydrogen chloride gas or chlorine gas atmosphere.

In the above method, the temperature inside the adsorption tower is set to 1
It is preferable that the concentration of hydrogen chloride gas or chlorine gas is set to 1 to 100 ppm (dry) at 00 to 200 ° C.

It is preferable to fill an adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas with activated carbon containing 0.01 to 5% by weight of chlorine as an adsorbent.

The activated carbon for removing harmful substances used in the above method is preferably one containing a chlorine content of 0.01 to 5% by weight in the production process.

The above-mentioned activated carbon is preferably obtained by impregnating an activated carbon raw material with an aqueous solution containing an inorganic chlorine compound and then activating the activated carbon raw material in the production process. As the activated carbon raw material, sawdust, wood chips, vegetable fiber, crushed charcoal, coconut shell and the like are used. Activation is performed by a conventional method such as a chemical activation method or a steam activation method.

[0010] Particularly preferred activated carbon is obtained by performing the activation in an atmosphere of hydrogen chloride gas or chlorine gas.

The above-mentioned activated carbon may be used before use, for example,
After activated carbon production, after filling in the adsorption tower (before exhaust gas treatment)
In the meantime, those containing 0.01 to 5% by weight of chlorine by exposure to a hydrogen chloride gas or chlorine gas atmosphere or by impregnation with hydrochloric acid water are also preferable.

[0012]

The apparatus and method for removing harmful substances according to the present invention and the activated carbon according to the present invention provide DXN
The efficiency of removing harmful substances such as harmful substances can be greatly increased.
Although the reason is not certain, the adsorption tower is provided upstream of the desalination unit, or hydrogen chloride gas or chlorine gas is injected into the adsorption tower, or hydrogen chloride gas or By including chlorine gas, HCl and Cl ₂ are preferentially adsorbed to the hydrophilic groups of the activated carbon, and the Cl groups convert these hydrophilic groups to hydrophobic groups, and thus the increased hydrophobic groups enhance DXN adsorption. It is considered something.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 This embodiment relates to an exhaust gas treatment apparatus provided with an adsorption tower and a smoke washing tower, that is, a desalination apparatus, in which an adsorption tower is provided upstream of the smoke washing tower. It shows. This flow sheet is as follows.

Electric dust collector → adsorption tower → smoke washing tower

In the above harmful substance removing apparatus, the flue gas discharged from the waste incinerator is firstly dusted off by an electric dust collector, then passed through an adsorption tower, and finally passed through a smoke washing tower. When the combustion exhaust gas is treated in this order, the inside of the adsorption tower becomes a hydrogen chloride gas atmosphere, and the adsorbent is exposed to the atmosphere.

The removal rate of DXN obtained by this operation was 0.73, and the removal rate of organic compounds (such as chlorobenzene) other than DXN was 0.52. This is about 1.2 times the corresponding value of Comparative Example 1 described later.

Example 2 The same operation as in Example 1 was repeated, except that a bag filter was installed instead of the electric dust collector. This flow sheet is as follows.

Bag filter → adsorption tower → smoke washing tower

No desalting agent is blown into the bag filter. When the flue gas is treated in this order, the inside of the adsorption tower is again in a hydrogen chloride gas atmosphere, and the adsorbent is exposed to the same atmosphere.

Example 3 Another harmful substance removing apparatus comprising a high-efficiency DXN removal adsorption tower is shown. In this example, DX from the bottom of the adsorption tower
N-containing exhaust gas flows into the tower. 10 ppm (dry) of hydrogen chloride gas or chlorine gas is injected into the inlet of the adsorption tower so that the inside of the adsorption tower becomes a hydrogen chloride gas or chlorine gas atmosphere.

Example 4 This example relates to a method for producing a highly efficient adsorbent for removing DXN.

First, 100 g of sawdust, a raw material of activated carbon, was immersed in an aqueous hydrochloric acid solution (1 molar concentration) for 5 hours and dried. Next, this was heat-treated at a temperature of 800 ° C. to be activated. The thus obtained activated carbon finally containing about 3% by weight of chlorine is used as an adsorbent for removing harmful substances.

Example 5 The same operation as in Example 4 was repeated except that the hydrogen chloride gas or chlorine gas was flowed into the inert gas atmosphere in the activation step without performing the impregnation treatment with the aqueous hydrochloric acid solution of Example 4. .

Example 6 Activated carbon was treated with hydrogen chloride gas or chlorine gas, and the gas was adsorbed on the activated carbon. The obtained flue gas was treated using the activated carbon finally containing about 2.5% by weight of chlorine as an adsorbent for removing harmful substances.
The removal rate of XN was 0.80, and the removal rate of organic compounds other than DXN was 0.54. This is about 1.3 times the corresponding value of Comparative Example 2 described later.

Example 7 100 g of activated carbon was immersed in a hydrochloric acid aqueous solution (1 molar concentration) for 5 hours and dried. The thus obtained activated carbon finally containing about 3% by weight of chlorine is used as an adsorbent for removing harmful substances.

Comparative Example 1 The flue gas discharged from a waste incinerator was firstly dusted off by an electric dust collector, and then passed through a smoke washing tower, that is, a desalination device.
Finally, it passes through the adsorption tower. This flow sheet is as follows.

Electric precipitator → Smoke tower → Adsorption tower

The removal rate of DXN obtained by this operation was 0.64, and the removal rate of organic compounds other than DXN was 0.42.

Comparative Example 2 The same operation as in Example 6 was repeated except that the activated carbon was not treated with hydrogen chloride gas or chlorine gas. As a result, the removal rate of DXN was 0.64. The removal rate of the organic compound was 0.42.

[0030]

According to the present invention, the efficiency of removing harmful substances such as DXN can be greatly improved. Therefore, the present invention greatly contributes to a reduction in the size of the adsorption tower and a reduction in the amount of the adsorbent used.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kiichi Nagaya 1-7-89 Minami Kohoku, Suminoe-ku, Osaka F-term in Tachibai Shipbuilding Corporation (reference) 4D002 AA21 AC04 BA04 BA14 CA07 DA26 DA41 DA70 EA05 EA06 EA07 GA01 GA02 GB02 GB03 GB08 HA10 4D012 BA03 4G066 AA05B AA08D AA34D BA36 CA33 DA02 FA12 FA18 FA37

Claims (8)

[Claims] 1. Exhaust gas comprising an adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas, and a desalination device for removing acidic gas components such as hydrogen chloride gas in the exhaust gas. An apparatus for removing harmful substances from exhaust gas, wherein an adsorption tower is provided on the upstream side of a desalination apparatus in the treatment apparatus and the inside of the adsorption tower is operated in a hydrogen chloride gas atmosphere. 2. Injecting hydrogen chloride gas or chlorine gas into an adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas, so that the inside of the tower becomes a hydrogen chloride gas or chlorine gas atmosphere. Characterized by
How to remove harmful substances in exhaust gas. 3. The temperature inside the adsorption tower is 100 to 200 ° C.
Hydrogen chloride gas or chlorine gas concentration of 1-100ppm
The method for removing harmful substances according to claim 2, wherein the method is (dry). 4. An adsorption tower for adsorbing harmful substances such as dioxins in waste combustion exhaust gas is filled with activated carbon containing 0.01 to 5% by weight of chlorine as an adsorbent. How to remove harmful substances in exhaust gas. 5. Activated carbon for adsorbing harmful substances such as dioxins in waste flue gas, characterized in that the production process contains a chlorine content of 0.01 to 5% by weight. , Activated carbon for removing harmful substances. 6. The harmful substance according to claim 5, wherein the activated carbon is obtained by impregnating an activated carbon raw material with an aqueous solution containing an inorganic chlorine compound and then activating the activated carbon raw material in the production process. Activated carbon for removal. 7. The activated carbon for removing harmful substances according to claim 6, wherein the activated carbon is obtained by performing activation in an atmosphere of hydrogen chloride gas or chlorine gas. 8. The method for removing harmful substances according to claim 4, wherein the activated carbon is exposed to a hydrogen chloride gas or a chlorine gas atmosphere or impregnated with hydrochloric acid before use.