KR100828703B1 - Equipment and method of treating nitrogen oxides in incinerator - Google Patents

Abstract

An apparatus and method for treating nitrogen oxides for incinerators are disclosed. The disclosed incinerator nitrogen oxide treatment apparatus includes a leachate storage tank for storing leachate generated from the waste in a device for treating nitrogen oxide in exhaust gas discharged from an incinerator for burning waste by a reduction reaction, and the leachate storage tank. Ammonia water generated by the microbial reaction from the leachate in the interior, a nitrogen oxide treatment tank for receiving the exhaust gas and reducing it by the ammonia water, and ammonia water disposed between the leachate reservoir and the nitrogen oxide treatment tank and generated in the leachate storage tank. It characterized in that it comprises ammonia water input line for supplying to the nitrogen oxide treatment tank.

Accordingly, the disclosed incinerator nitrogen oxide treatment apparatus and method can reduce the overall operating cost by reducing the reducing agent cost and leachate disposal costs.

Description

Equipment and method of treating nitrogen oxides in incinerator}

1 is a view showing the configuration of an incineration exhaust gas treatment system having a nitrogen oxide treatment apparatus for incinerators according to an embodiment of the present invention.

2A to 2C are views schematically showing various forms of a leachate storage tank provided in a nitrogen oxide treatment apparatus for an incinerator according to the present invention.

3A and 3B are cross-sectional views schematically illustrating a form in which the carrier is filled when the carrier is provided in the leachate storage tank of the incinerator nitrogen oxide treatment apparatus according to the present invention.

4a and 4b are cross-sectional views schematically showing different forms of the leachate return line provided in the leachate storage tank of the nitrogen oxide treatment apparatus for incinerators according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: incinerator 2: centrifugal dust collector

3: compressor 4: alkaline material supply tank

5: alkali material supply line 6: semi-dry reactor

7: Atomizing nozzle 8: Fly ash dust collector

9: conveyor belt 10: sediment collection tank

11: nitrogen oxide treatment tank 12: leachate input line

13: Leachate reservoir 14: Leachate discharge line

15: leachate return line 15a, 15a ′: leachate distribution pipe

16: ammonia water input line 17: blower

18: stack 19, 19 ': carrier

The present invention relates to a nitrogen oxide treatment apparatus and method for incinerators, and more particularly to a nitrogen oxide treatment apparatus and method for incinerators that can reduce the operating cost.

In general, exhaust gases emitted from waste incinerators contain trace components such as fly ash, hydrogen chloride (HCl), sulfur oxides (SOx), nitrogen oxides (NOx), heavy metals containing mercury, or dioxins. These hazardous ingredients must be removed to protect the environment.

The facilities for purifying exhaust gas can be roughly divided into a sulfur oxide treatment apparatus for removing sulfur oxides, a dust treatment apparatus for removing dust such as fly ash, and a nitrogen oxide treatment apparatus for removing nitrogen oxides. .

Among them, the nitrogen oxide treatment apparatus injects a reducing agent such as ammonia (NH ₃ ), carbon monoxide (CO), or hydrogen sulfide (H ₂ S) into the exhaust passage to contact the exhaust gas, thereby contacting the nitrogen oxide and the reducing agent. It is a device that removes nitrogen oxides by causing a reduction reaction.

The nitrogen oxide treatment apparatus may be classified into selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) depending on whether a catalyst is used. In the selective catalytic reduction apparatus (SCR), first, a reducing agent is injected into the exhaust gas, and then the mixture passes through a catalyst layer such as TiO ₂ or V ₂ O ₅ to cause denitrification. The optimum denitrification temperature is 300 to 450 ° C. At temperatures below 300 ° C, the catalytic activity decreases, which is undesirable. If the temperature exceeds 450 ° C, ammonia is oxidatively decomposed, which is not preferable. In a selective non-catalyst reduction apparatus (SNCR), a denitrification reaction occurs in a temperature range of 870 to 1,200 ° C without a catalyst by injecting a reducing agent into the exhaust gas. The selective non-catalytic reduction device (SNCR) has a lower construction cost and maintenance cost than the selective catalytic reduction device (SCR).

As described above, the conventional nitrogen oxide treatment apparatus has a problem of separately injecting an expensive reducing agent from the outside.

It is an object of the present invention to provide a nitrogen oxide treatment apparatus and method for an incinerator that can reduce a reducing agent.

Still another object of the present invention is to provide a nitrogen oxide treatment apparatus and method for an incinerator that can reduce the cost of leachate disposal.

According to the invention,

An apparatus for treating nitrogen oxide in exhaust gas discharged from an incinerator for burning wastes by a reduction reaction,

Leachate storage tank for storing the leachate generated from the waste,

Ammonia water generated by the microbial reaction from the leachate in the leachate reservoir,

A nitrogen oxide treatment tank receiving the exhaust gas and reducing it by the ammonia water, and

A nitrogen oxide treatment apparatus for an incinerator is disposed between the leachate reservoir and the nitrogen oxide treatment tank and has an ammonia water input line for supplying ammonia water generated in the leachate reservoir to the nitrogen oxide treatment tank.

According to one embodiment of the invention, the leachate storage tank, the leachate input line receiving the leachate from the waste, the leachate discharge line, and the leachate return line for returning the leachate to the leachate storage tank, the leachate discharge line The ammonia water input line is connected to one side of the leachate return line is connected to the other side.

According to another embodiment of the present invention, at the end extending to the inner top of the leachate storage tank of the leachate return line is provided with a straight leachate distribution pipe and the leachate distribution pipe is formed with a plurality of outlets.

According to another embodiment of the invention, the leachate reservoir is spherical.

According to another embodiment of the invention, the leachate reservoir is cylindrical.

According to a preferred embodiment of the present invention, the leachate reservoir is maintained in anaerobic conditions.

According to another embodiment of the invention, the leachate reservoir is maintained in aerobic conditions.

According to another embodiment of the invention, the leachate reservoir is maintained in semi-anaerobic conditions.

According to another embodiment of the present invention, the leachate reservoir is filled with a carrier for supporting microorganisms.

According to another embodiment of the present invention, the carrier is filled in the leachate reservoir in fluid form.

According to another embodiment of the present invention, the carrier is filled in the leachate reservoir in the form of a stationary phase.

Also according to the invention.

In a method for treating nitrogen oxide in exhaust gas discharged from an incinerator for burning wastes by a reduction reaction,

(a) generating ammonia water by microbial reaction from the leachate from the waste,

(B) there is provided a nitrogen oxide treatment method for an incinerator comprising the step of reducing the exhaust gas using the ammonia water.

According to an embodiment of the present invention, the step of (a) and at the same time further comprises the step of mixing the leachate.

According to a preferred embodiment of the present invention, step (a) is carried out under anaerobic conditions.

According to another embodiment of the present invention, step (a) is carried out under aerobic conditions.

According to another embodiment of the present invention, step (a) is performed under semi-anaerobic conditions.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing the configuration of an incineration exhaust gas treatment system having a nitrogen oxide treatment apparatus for incinerators according to an embodiment of the present invention.

1, the incineration exhaust gas treatment apparatus according to the present embodiment is an incinerator (1), centrifugal dust collector (2), semi-dry reactor (6), fly ash dust collector (8), sediment collection tank (10), nitrogen oxide treatment A device, a blower 17, and a stack 18.

The incinerator 1 burns waste, and the exhaust gas discharged from the incinerator 1 includes fly ash generated from the combustion process, acid gases (HCl, SOx, HF, H ₂ S, etc.) and nitrogen oxides. Harmful air pollutants include (NO, NO ₂ ), heavy metals (Hg, As, Pb, etc.), dioxins (PCDD, PCDF), and volatile organic compounds (VOCs).

The centrifugal dust collector 2 receives exhaust gas discharged from the incinerator 1 and primarily removes particulate matter having a large particle size. The exhaust gas discharged through the centrifugal dust collector 2 flows into the semi-dry reactor 6 described later. Such a centrifugal dust collector 2 may not be provided by selection.

 The semi-dry reactor 6 neutralizes the acidic exhaust gas of the inflowed exhaust gas with an alkaline substance, and an injection nozzle 7 for supplying the alkaline substance is provided at the upper portion thereof. The injection nozzle 7 is connected to the compressor 3 and the alkaline material supply tank 4 through the alkaline material supply line 5 and serves to disperse the alkaline material into fine particles. Here, as the alkaline substance, sodium hydroxide, sodium carbonate, calcium hydroxide, or magnesium hydroxide may be used. In addition, the injection nozzle 7 may be installed at various other positions such as the upper part of the semi-dry reactor 6 as well as the lower part or the side part thereof. In the semi-dry reactor (6) by using a spray nozzle (7) installed therein by spraying a mixture of water and alkaline substances in a certain ratio with fine particles having a diameter of several tens to hundreds of micrometers to contact with the hot exhaust gas Through the reaction mechanism of absorption, drying and adsorption, pollutants in the exhaust gas are removed. That is, in the semi-dry reactor (6) it can be seen that the neutralization reaction between the alkali material and the acid gases. The exhaust gas containing the fly ash discharged from the semi-dry reactor 6 is introduced into the fly ash dust collector 8 described later to remove the fly ash from the exhaust gas.

The collecting hopper 6a is provided in the lower part of the semi-dry reactor 6, and the fly ash discharge port 6b is provided in the lower end of this collection hopper 6a. Through the collection hopper 6a and the fly ash outlet 6b, dry matter such as a reaction product generated by spraying fly ash and alkaline substances accumulated in the semi-dry reactor 6 as the treatment time elapses is discharged to the outside. The dried product is introduced into the sediment collection tank 10 through the conveyor belt (10). Here, the conveyor belt 10 may not be installed by selection, in which case the dry matter is introduced directly into the sediment collection tank 10.

The fly ash dust collector 8 is installed at the rear end of the semi-dry reactor 6 and serves to remove fly ash from the exhaust gas. As the fly ash dust collector 8, a catalytic reduction reactor, a catalytic reduction reactor, an activated carbon adsorption tower, a cyclone, or a bag filter may be used. The collecting hopper 8a is provided in the lower part of the fly ash dust collector 8, and the fly ash discharge port 8b is provided in the lower end of this collection hopper 8a. Through the fly ash outlet 8b, dry matter such as fly ash accumulated in the fly ash dust collector 8 is discharged to the outside as the processing time passes. The dried product is introduced into the sediment collection tank 10 through the conveyor belt (10). Here, the conveyor belt 10 may not be installed by selection as described above.

A nitrogen oxide treatment apparatus is installed at the rear end of the fly ash dust collector 8, and the nitrogen oxide treatment apparatus includes a nitrogen oxide treatment tank 11 and a leachate storage tank 13.

The nitrogen oxide treatment tank 11 receives the exhaust gas and is responsible for reducing nitrogen oxide in the exhaust gas with a reducing agent such as ammonia water. Here, the nitrogen oxide contained in the exhaust gas is generated as the nitrogen in the combustion gas and the nitrogen contained in the waste are oxidized. Nitrogen oxides mainly contain nitrogen monoxide (NO) and nitrogen dioxide (NO ₂ ). Such nitrogen oxide is reduced by a reducing agent such as ammonia water while passing through the nitrogen oxide treatment tank 11, and when ammonia water is used as the reducing agent, the chemical formula is as follows.

[Formula 1]

2NO ₂ + O ₂ + 4NH ₃ → 3N ₂ + 6H ₂ O

[Formula 2]

4NO + O ₂ + 4NH ₃ → 4N ₂ + 6H ₂ O

Nitrogen oxides are reduced to nitrogen gas (N ₂ ) and water (H ₂ O), which are harmless to the human body, by the reduction reaction with ammonia water and air according to the above formulas (1) and / or ( ₂ ).

In this embodiment, instead of using a separate reducing agent, ammonia water generated in the leachate described later is used.

On the other hand, in the nitrogen oxide treatment tank 11 as described above, both selective catalytic reduction technology (SCR) or selective non-catalytic reduction technology (SNCR) may be employed.

Leachate storage tank 13 is a place for receiving and storing the leachate generated from the waste loaded in the incinerator through the leachate input line 12. In the leachate reservoir 13, the microorganisms originally contained in the leachate react with the nitrogen component in the leachate to generate ammonia water. The residence time of the leachate in the leachate reservoir 13, the operating temperature of the leachate reservoir 13, and the shape thereof may vary depending on the leachate conditions. Here, the operating temperature of the leachate storage tank 13 is preferably maintained at medium temperature (25 ~ 40 ℃) or room temperature (40 ~ 60 ℃) in order to improve the microbial reaction rate.

The leachate storage tank 13 includes a leachate input line 12, a leachate discharge line 14, and a leachate return line 15. The leachate input line 12 is a passage through which the leachate generated from the waste is transferred to the leachate storage tank 13. The leachate discharge line 14 is a passage through which the leachate is discharged from the leachate storage tank 13 so that the leachate is transferred to the leachate return line 15 and the ammonia water input line 16, which will be described later. That is, the ammonia water input line 16 is connected to one side of the leachate discharge line 14 and the leachate return line 15 is connected to the other side. One end of the leachate return line 15, that is, the opposite end of the side connected to the leachate discharge line 14, is connected to the leachate reservoir 13. In this way, the leachate discharged from the leachate storage tank 13 through the leachate discharge line 14 is returned to the leachate storage tank 13 by a predetermined amount. That is, the leachate in the leachate reservoir 13 is continuously recycled to a certain amount, whereby the leachate in the leachate reservoir 13 is continuously and uniformly mixed. The leachate mixing method in the leachate storage tank 13 using the leachate return line 15 will be described later in more detail.

As such, the leachate in the leachate reservoir 13 is uniformly mixed, whereby a dead zone is prevented from being generated inside the leachate reservoir 13, which in turn results in an improvement in the efficiency of the microbial reaction. The method of uniformly mixing the leachate in the leachate storage tank 13 is not limited thereto, and various other methods such as using an ultrasonic wave or an agitator may be used.

One end of the ammonia water input line 16, that is, the opposite end of the side connected to the leachate discharge line 14, is connected to the nitrogen oxide treatment tank 11. In this way, the leachate discharged from the leachate storage tank 13 through the leachate discharge line 14 is introduced into the nitrogen oxide treatment tank 11 through the ammonia water input line 16. In this way, the leachate introduced into the nitrogen oxide treatment tank 11 through the ammonia water input line 16 contains a predetermined amount of ammonia water generated in the leachate storage tank 13. Therefore, when using the nitrogen oxide treatment apparatus according to the present invention, there is no need to use a separate reducing agent, thereby reducing the reducing agent cost. In addition, since the leachate generated from the waste is recycled with a certain amount of reducing agent, the amount of leachate to be finally disposed of may be reduced, thereby reducing the cost of leachate disposal.

 The shape of the leachate reservoir 13 may be variously changed, such as spherical and cylindrical, as shown in FIGS. 2A to 2C. Here, the same reference numerals as in the above-described drawings indicate the same components or parts of the same components.

The production of ammonia water in the leachate reservoir 13 is preferably performed under anaerobic conditions, but the present invention is not limited thereto, and may be performed under aerobic or semi-anaerobic conditions. Under anaerobic conditions, the amount of reacting with oxygen in the nitrogen component in the nitrogen oxide is reduced, so that most of the nitrogen component is converted into ammonia form as shown in the following formula (3). On the other hand, in aerobic conditions, the nitrogen component is reacted with a large amount of oxygen and converted to nitric acid or nitrogen in addition to the ammonia form as shown in the following formula (4). Thus, more ammonia water can be obtained under anaerobic conditions than under aerobic conditions.

[Formula 3]

N → NH ₃ + NH ^{4 +}

[Formula 4]

_{^{N → NH 3 + NH 4 +}} + N 2 + NO 3 -

The leachate reservoir 13 may be filled with a carrier for supporting microorganisms. The carrier is for promoting the growth of microorganisms inherently present in the leachate, and as shown in FIGS. 3A and 3B, the carriers 19, 19 ′ are in fluidized form in the leachate reservoir 13 (FIG. 3A). It may be filled or filled in stationary phase (FIG. 3B). In this way, when the leachate is discharged through the leachate discharge line 14 by fixing the microorganisms to the carriers 19 and 19 ', the discharge of the microorganisms can be minimized. Therefore, by maintaining a large amount of microorganisms in the leachate storage tank 13 it is possible to maximize the production of ammonia water by the microbial reaction. As such a carrier, various materials such as polymer, ceramic, or activated carbon may be used.

4A and 4B are cross-sectional views schematically showing different forms of the leachate return lines 15 and 15 'provided in the leachate storage tank 13 of the nitrogen oxide treatment apparatus for an incinerator according to the present invention. Here, the same reference numerals as in the above-described drawings indicate the same components or parts of the same components.

4A and 4B, one end of the leachate return line 15, 15 'is provided with a straight leachate distribution pipe (15a, 15a'). More specifically, the leachate distribution pipe (15a, 15a ') is provided at one end of the leachate return line 15, that is, the end extending to the inner upper end of the leachate reservoir (13). In addition, a plurality of discharge ports 15b and 15b 'are formed in the leachate distribution pipes 15a and 15a'. In this way, a predetermined amount of the leachate discharged from the leachate storage tank 13 is sequentially passed through the return line 15 through the leachate distribution pipes 15a and 15a 'and the outlets 15b and 15b'. From bottom to bottom over a wide area. Therefore, the small amount of leachate returned is uniformly mixed with a large amount of leachate in the leachate reservoir 13.

The blower 17 and the stack 18 are sequentially installed at the rear end of the nitrogen oxide treatment tank 11, and the exhaust gas discharged from the nitrogen oxide treatment tank 11 is discharged to the outside through the 17 and 18. .

On the other hand, in the present embodiment has been described by taking an incinerator nitrogen oxide treatment apparatus according to the present invention in an incineration exhaust gas treatment system having a semi-dry reactor as an example, the present invention is not limited thereto, but incinerator according to the present invention The nitrogen oxide treatment apparatus may be used in incineration exhaust gas treatment systems having various other configurations.

Although the preferred embodiment according to the present invention has been described above, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the protection scope of the present invention should be defined by the appended claims.

According to the present invention, there can be provided a nitrogen oxide treatment apparatus and method for an incinerator that can reduce the reducing agent.

In addition, according to the present invention, there can be provided a nitrogen oxide treatment apparatus and method for an incinerator that can reduce the leachate disposal costs.

Claims (16)

An apparatus for treating nitrogen oxide in exhaust gas discharged from an incinerator for burning wastes by a reduction reaction, Leachate storage tank for storing the leachate generated from the waste; Ammonia water generated by the microbial reaction from the leachate in the leachate reservoir; A nitrogen oxide treatment tank for receiving the exhaust gas and reducing the exhaust gas with the ammonia water; And And an ammonia water input line disposed between the leachate reservoir and the nitrogen oxide treatment tank to supply ammonia water generated in the leachate storage tank to the nitrogen oxide treatment tank. The method of claim 1, The leachate storage tank includes a leachate input line receiving leachate from the waste, a leachate discharge line, and a leachate return line for returning the leachate to the leachate storage tank, And an ammonia water input line and the leachate return line are connected to each other so as to communicate with each other. The method of claim 2, Nitrogen oxide treatment apparatus for an incinerator, characterized in that the leachate distribution pipe of the leachate is provided at the end extending to the upper end of the leachate storage tank of the leachate return line is formed in the leachate distribution pipe. The method of claim 1, The leachate storage tank is nitrogen oxide processing apparatus for an incinerator, characterized in that the sphere. The method of claim 1, The leachate storage tank is nitrogen oxide processing apparatus for an incinerator, characterized in that the cylindrical. The method according to claim 4 or 5, The leachate storage tank is nitrogen oxide treatment apparatus for an incinerator, characterized in that maintained in anaerobic conditions. The method according to claim 4 or 5, The leachate storage tank is nitrogen oxide processing apparatus for an incinerator, characterized in that maintained in aerobic conditions. The method according to claim 4 or 5, The leachate storage tank is nitrogen oxide processing apparatus for an incinerator, characterized in that maintained in a semi-anaerobic condition. The method of claim 1, The leachate storage tank is nitrogen oxide processing apparatus for an incinerator, characterized in that the carrier for supporting the microorganism is filled. The method of claim 9, The carrier is nitrogen oxide treatment apparatus for an incinerator, characterized in that the leachate storage tank is filled in the form of a fluidized bed. The method of claim 9, The carrier is nitrogen oxide treatment apparatus for an incinerator, characterized in that the leachate storage tank is filled in a fixed phase form. In a method for treating nitrogen oxide in exhaust gas discharged from an incinerator for burning wastes by a reduction reaction, (a) generating ammonia water by the microbial reaction from the leachate from the waste; And (b) a nitrogen oxide treatment method for an incinerator comprising the step of reducing the exhaust gas using the ammonia water. The method of claim 12, The nitrogen oxide treatment method for an incinerator further comprising the step of mixing the leachate simultaneously with the step (a). The method of claim 12, The step (a) is a nitrogen oxide treatment method for an incinerator, characterized in that carried out under anaerobic conditions. The method of claim 12, The step (a) is nitrogen oxide treatment method for incinerator, characterized in that carried out under aerobic conditions. The method of claim 12, The step (a) is nitrogen oxide treatment method for incinerator, characterized in that carried out under semi-anaerobic conditions.

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