JPH0531323A - Method for exhaust gas treatment - Google Patents

Abstract

PURPOSE:To provide a method for exhaust gas treatment requiring no large scale equipment and removing harmful substances in the exhaust gas with a high efficiency. CONSTITUTION:In a combustion exhaust gas line at the outlet of a boiler, a sprayer 1 for powdery activated carbon and, downstream of it, a sprayer 2 for a basic absorbent to remove acid components are installed. The substances captured by the activated carbon and the absorbent are collected in a dust catcher 3 with the activated carbon and the absorbent and removed. The combustion exhaust gas eliminated of harmful substances is discharged from a stack 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment method for removing harmful substances in combustion exhaust gas discharged from an incinerator facility. The harmful substances include heavy metals such as mercury and organic chlorine compounds such as dioxins.

[0002]

BACKGROUND OF THE INVENTION Many methods have been shown to remove or recover mercury from flue gas. In addition, various methods have been shown as a method for reducing harmful chlorine compounds such as dioxins in flue gas. PCT application WO85 /
According to the 03455 specification, activated carbon or coke is used on a fixed bed. This method has the disadvantages that the particle size of the activated carbon or the like becomes relatively coarse, the production of the particulate activated carbon is expensive, and the activity of the activated carbon or the like becomes low.

[0003]

In the conventional method, there is room for improvement in that a large-scale device is required and the removal efficiency is not good. Accordingly, there is a need for improved methods of removing mercury vapor and / or harmful organic compounds from flue gases. The present invention has been made based on this point of view, and an object thereof is to provide an exhaust gas treatment method capable of solving the above-mentioned drawbacks of the prior art.

[0004]

In order to achieve the above object, in the method of the present invention, a powdered activated carbon having a high adsorptivity is installed as an exhaust gas treatment facility from an incinerator facility without installing a large apparatus. By spraying in the exhaust gas,
It is characterized by efficiently adsorbing harmful substances in exhaust gas and collecting and removing them with a dust collector installed downstream. The powdered activated carbon can be sprayed upstream and / or downstream of the step of absorbing the acidic component by spraying the basic absorbent in the exhaust gas in a dry state.

[0005]

The method according to the present invention sprays powdered activated carbon into the combustion exhaust gas from a general refuse incineration plant, adsorbs heavy metals such as mercury in the exhaust gas to the activated carbon,
It also adsorbs harmful organic chlorine compounds such as dioxins. Activated carbon on which these harmful substances are adsorbed is collected by a dust collector such as a bag filter provided downstream and excluded from the exhaust gas.

Generally, the combustion exhaust gas contains an acidic component such as hydrogen chloride. To remove the acidic component, a basic absorbent is sprayed into the exhaust gas. The basic absorbent absorbs exhaust gas with a gas cooling device such as a gas cooler.
It is supplied after cooling to 0 ° C to 200 ° C. Further, the basic absorbent is sprayed inside the exhaust gas line after installing the dry reaction tower at the boiler outlet in the exhaust gas line or directly in the exhaust gas line.

Therefore, the method of the present invention is the same position as the spraying position of the basic absorbent in the exhaust gas line (the above-mentioned dry reaction tower installation position or direct spraying position), or upstream and / or above that position.
Alternatively, the spray position of the powdered activated carbon is arranged at the downstream position.

In order to enhance the adsorption activity of the powdered activated carbon, a powder having a particle size of less than 44 μm and a particle size of 30 wt% was used as a trial, and the flue gas Nm ³ The amount is 1 to 600 mg per spray.

[0009]

1 to 3 are views showing different flows in an incinerator facility to which the method according to the present invention is applied. Corresponding parts in the drawings are designated by the same reference numerals.

In the first embodiment shown in FIG. 1, in the combustion exhaust gas line at the outlet of the boiler, a spraying section 1 for powdered activated carbon is provided.
And the spraying section 2 of the basic absorbent for removing the acidic component is disposed downstream thereof. The substances adsorbed on the activated carbon and the absorbent are collected and removed together with them by the dust collector 3, and the combustion exhaust gas from which the harmful substances are removed is discharged from the stack 4 to the outside of the system.

In the embodiment shown in FIG. 2, the spraying part 1 of powdered activated carbon and the spraying part 2 of the basic absorbent are arranged in an upstream / downstream relationship opposite to that of the first embodiment. The dust collector 3 and the stack 4 are the same as in the first embodiment.

In the embodiment shown in FIG. 3, the spraying section 1 of powdered activated carbon and the spraying section 2 of the basic absorbent are arranged at the same position. The dust collector 3 and the stack 4 are the same as in the first embodiment.

The powdered activated carbon can be supplied from a silo while being quantitatively controlled by a screw feeder or the like, and can be sprayed into the exhaust gas by compressed air. Alternatively, the powdered activated carbon can be sprayed using any other suitable means.

Table 1 shows the analysis results of harmful substances in the exhaust gas in the first embodiment. As shown in this result,
According to the incinerator equipment to which the method of the present invention is applied, Hg and dioxin in the combustion exhaust gas are removed with high efficiency.

[0015]

[Table 1]

[0016]

According to the method of the present invention, it is possible to remove harmful substances such as mercury and dioxins in exhaust gas with high efficiency without requiring a large-scale device.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of an incinerator facility to which an exhaust gas treatment method according to the present invention is applied.

FIG. 2 is a diagram showing a second embodiment of incinerator equipment to which the exhaust gas treatment method according to the present invention is applied.

FIG. 3 is a diagram showing a third embodiment of incinerator equipment to which the exhaust gas treatment method according to the present invention is applied.

[Explanation of symbols]

1 ... Powdery activated carbon spraying part, 2 ... Basic absorbent spraying part, 3
… Dust collector, 4… Stack.

Front Page Continuation (72) Inventor Tsuyoshi Nakao 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kentaro Ito 1-2-1, Marunouchi, Chiyoda-ku, Tokyo In the company

Claims (1)

Claim: What is claimed is: 1. A method for removing harmful substances in a combustion exhaust gas discharged from an incinerator facility, comprising:
After cooling to 0 ° C. to 200 ° C., a step of spraying a basic absorbent for absorbing an acidic component into the exhaust gas line in a dry state, and including 30 wt% of a particle size of 44 μm or less in the exhaust gas line Powdered activated carbon was added to the above exhaust gas Nm ³ Spraying 1 to 600 mg per step, and collecting the powdered activated carbon adsorbing harmful substances with a dust collector provided in the exhaust gas line downstream of the spraying position of the basic absorbent and the spraying position of powdered activated carbon A method for treating exhaust gas, comprising: