KR100927327B1 - Nitrogen oxide reduction device and method for exhaust gas - Google Patents

Abstract

In the apparatus and method for reducing nitrogen oxides in exhaust gas, the apparatus for reducing nitrogen oxides has a reactor body having a gas-liquid contact therein, a gas inlet for introducing exhaust gas containing nitrogen oxides into the reactor body, and exhaust gas from the reactor body. And a gas-liquid contact unit having a gas outlet, and a liquid supply unit connected to the gas-liquid contact part to supply a nitrogen oxide removal liquid including sulfuric acid, urea and water to the gas-liquid contact part. The nitrogen oxide reduction device can remove nitrogen oxide contained in the exhaust gas at high temperature with high efficiency.

Description

Apparatus and method for reducing nitrogen oxides in an exhaust gas

The present invention relates to a nitrogen oxide reduction device and a nitrogen oxide reduction method. More particularly, the present invention relates to a nitrogen oxide reduction device used to remove nitrogen oxides contained in exhaust gas and a method for removing nitrogen oxides using the same.

Nitrogen oxide (NOx) is a material that combines nitrogen and oxygen such as NO, NO ₂ , etc. In addition, the nitrogen components contained in the fuel are thermally decomposed into low molecular weight nitrogen compounds such as NH ₃ , HCN and CN, and these substances are generated by reaction with oxygen. In addition to the combustion process, nitrogen oxides are also frequently generated in the etching process using nitric acid. For example, in the etching process of copper and silicon, nitrogen oxides may be generated according to the following reaction formulas (1) to (3).

3Cu + 8HNO ₃ (dilute) → 3Cu (NO ₃ ) ₂ + 4H ₂ O + 2NO ...... (1)

Cu + 4HNO ₃ (conc.) → Cu (NO ₃ ) ₂ + 2H ₂ O + 2NO ₂ ...... (2)

3Si + 4HNO ₃ → 3SiO ₂ + 4NO + 2H ₂ O ...... (3)

Nitrogen oxide generated as described above is not only a cause of acid rain, but also causes photochemical smog, which causes eye and respiratory diseases, and is known as a pollutant that is a main culprit of global warming together with carbon dioxide. Therefore, studies have been actively conducted to reduce nitrogen oxide emissions or to remove nitrogen oxides in consideration of environmental pollution and human hazards.

As a technique for reducing the emission of nitrogen oxides, a method of using a raw material having a low nitrogen content or removing a nitrogen component from the raw material has been considered. In addition, when oxidation of nitrogen in the air during the combustion process is a major source of nitrogen oxides, a technique for suppressing the generation of nitrogen oxides by adjusting the temperature and oxygen concentration of the combustion process has been developed.

Meanwhile, techniques for removing nitrogen oxides that have already been generated are largely classified into Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) depending on the use of a catalyst.

Selective catalytic reduction, a representative method for the removal of nitrogen oxides, uses NH ₃ , CO, H ₂ S, etc. Mainly, ammonia (NH ₃ ) is injected into the exhaust gas, and the exhaust gas is passed through a catalyst layer such as TiO ₂ , WO ₃ , V ₂ O ₅ , MoO ₃ , and maintained at a temperature of 300 ° C. to 400 ° C. Treat nitrogen oxides.

The selective catalytic reduction method has a relatively high removal rate of nitrogen oxides of 70-90%, which has the advantage of simple and stable operation. However, the cost of equipment is high, and the use of expensive catalysts and SO ₂ contained in the exhaust gas shortens the life of the catalysts, resulting in a large maintenance cost due to frequent catalyst replacements.

The selective non-catalytic reduction method is a method of treating nitrogen oxide by injecting ammonia or urea water into the exhaust gas at a high temperature of 700 ° C to 1,100 ° C without using a catalyst. The selective non-catalytic reduction method is easy to apply to incinerators that do not need to use a separate fuel, but other exhaust facilities require enormous costs to maintain high temperatures and require a large amount of reducing agent to maintain high efficiency. have.

Accordingly, an object of the present invention is to provide an apparatus for reducing nitrogen oxides of exhaust gas, which can reduce nitrogen oxides economically and efficiently at low temperatures.

Another object of the present invention is to provide a method for reducing nitrogen oxides in exhaust gas which can reduce nitrogen oxides economically and efficiently at low temperatures.

An apparatus for reducing exhaust gas nitrogen oxide according to an embodiment for achieving the above object of the present invention includes a reactor body having a gas-liquid contact therein, a gas inlet for introducing exhaust gas containing nitrogen oxide into the reactor body, and A gas-liquid contact unit having a gas outlet for discharging the exhaust gas from the reactor body, and a liquid supply unit connected to the gas-liquid contact unit to supply nitrogen oxide removal liquid including sulfuric acid, urea and water to the gas-liquid contact unit. do.

According to an embodiment of the present invention, the nitrogen oxide removal liquid may include sulfuric acid at a concentration of 10 to 40 w / v%, and urea at a concentration of 1 to 15 w / v%.

According to one embodiment of the invention, the gas-liquid contact unit may further include a liquid outlet located in the lower portion of the reactor body and connected to the liquid supply unit.

According to an embodiment of the present invention, the nitrogen oxide reduction device may further include a blower located inside or outside the gas-liquid contact unit.

According to an embodiment of the present invention, the nitrogen oxide reduction device may further include a liquid regeneration unit connected to the liquid supply unit and regenerating the nitrogen oxide removal liquid.

In a method for reducing nitrogen oxides in exhaust gas according to an embodiment for achieving the above object of the present invention, the nitrogen oxide removal liquid containing sulfuric acid, urea, and water is brought into contact with the exhaust gas containing nitrogen oxides to exhaust the exhaust gas. Remove nitrogen oxides from the gas.

In addition, in the method for reducing the nitrogen oxides of the exhaust gas according to an embodiment of the present invention for achieving another object of the present invention described above, the exhaust gas containing nitrogen oxide is introduced into the gas-liquid contact unit having a gas-liquid contact portion, The nitrogen oxide removal liquid containing sulfuric acid, urea and water is supplied to the gas-liquid contact unit. The nitrogen gas is removed from the exhaust gas by contacting the exhaust gas with the nitrogen oxide removal liquid in the gas-liquid contact portion, and then the exhaust gas from which the nitrogen oxide is removed is discharged from the gas-liquid contact unit.

According to an embodiment of the present invention, the nitrogen oxide removal liquid in contact with the exhaust gas may be recovered and resupplied to the gas-liquid contact unit.

According to one embodiment of the present invention, there are a plurality of gas-liquid contact units, and the exhaust gas discharged from the first gas-liquid contact unit may flow into the second gas-liquid contact unit to make secondary contact with the nitrogen oxide removal liquid.

The above-described apparatus and method for reducing nitrogen oxides of exhaust gases of the present invention can remove nitrogen oxides contained in exhaust gases with high efficiency by using a wet solution for removing nitrogen oxides. Therefore, since the expensive solid catalyst used in the conventional selective catalytic reduction method is not used, the facility cost and maintenance costs associated with the use of the solid catalyst can be greatly reduced. In addition, in the above-described method, since nitrogen oxides are removed at a low temperature such as room temperature, fuel costs can be reduced because heat processes such as heating of a reducing agent are not involved, and secondary generation of nitrogen oxides due to combustion of air can be prevented. It can remove nitrogen oxides economically and environmentally.

EMBODIMENT OF THE INVENTION Hereinafter, the nitrogen oxide reduction apparatus and method of exhaust gas of this invention are demonstrated in detail.

As the inventive concept allows for various changes and numerous modifications, the embodiments will be described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "consist of" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described on the specification, but one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

1 is a schematic diagram of a nitrogen oxide reduction device having one gas-liquid contact unit according to an embodiment of the present invention.

Referring to FIG. 1, a nitrogen oxide reduction apparatus 100 according to embodiments of the present invention includes a gas liquid having a reactor body 110, a gas inlet 112, a gas liquid contacting part 114, and a gas outlet 116. And a liquid supply unit connected to the contact unit and the gas-liquid contact unit to supply a nitrogen oxide removal liquid including sulfuric acid, urea and water to the gas-liquid contact unit.

Specifically, the gas-liquid contact unit includes a gas inlet 112 located at one side of the reactor body 110, and exhaust gas containing nitrogen oxides is passed through the gas inlet 112 to the reactor body 110. Can be introduced. The introduced exhaust gas comes out of the reactor body 110 through the gas outlet 116 after contacting with the nitrogen oxide removal liquid supplied from the liquid supply unit while passing through the gas-liquid contact 114.

The gas-liquid contact portion 114 is configured to induce contact between the nitrogen oxide removal liquid and the exhaust gas. For example, a spray tower type having a plurality of spray nozzles, a packed tower type having a packed bed, a venturi scrubber type, a baffle spray scrubber type Although these etc. are mentioned, It is not limited to these.

The nitrogen oxide abatement apparatus 100 according to embodiments of the present invention includes a liquid supply unit for supplying a nitrogen oxide removal liquid including sulfuric acid, urea, and water to the gas-liquid contact portion 114. The liquid supply unit is not particularly limited in configuration, and may include, for example, a liquid tank 120, a liquid supply pump 122, and a liquid supply pipe 124. The liquid tank 120 includes a nitrogen oxide removal liquid including sulfuric acid, urea, and water, and the nitrogen oxide removal liquid is supplied to the gas-liquid contact portion 114 through the liquid supply pipe 124.

According to embodiments of the present invention, the reactor body 110 of the gas-liquid contact unit may further include a liquid outlet 118 at the bottom. The reaction product of the liquid phase discharged through the liquid discharge port 118 may be discharged to the outside of the nitrogen oxide reduction device 100, but may be recovered to the liquid tank 120 in consideration of reuse of the nitrogen oxide removal liquid. In this case, the liquid outlet 118 has a structure connected to the liquid tank 120 as shown in FIG.

In addition, according to embodiments of the present invention, the reactor body 110 and the liquid tank 120 may have a separate structure as shown in FIG. 1, but may also have an integrated structure. In this case, a lower portion of the reactor body 110 serves as a liquid tank, and nitrogen oxide removal liquid may be supplied to the gas-liquid contact portion 114 through a liquid supply pipe 124 connected to the lower portion of the reactor body 110.

The nitrogen oxide removal solution is an aqueous solution containing sulfuric acid, urea and water, and in consideration of the removal efficiency of nitrogen oxide, sulfuric acid is about 10 to about 40w / v% (w / v% is the weight of the component (g) in 100mL of the solution). And urea at a concentration of about 1 to about 15 w / v%. More preferably, sulfuric acid may be included in a concentration range of about 15 to about 30 w / v% and urea may be included in a concentration range of about 5 to about 10 w / v%.

The nitrogen oxide reduction apparatus according to an embodiment of the present invention may further include a liquid regeneration unit for regenerating the nitrogen oxide removal liquid connected to the liquid tank 120. The liquid regeneration unit may include a liquid regeneration unit 140 and a liquid supply valve 142 as a means for maintaining the concentrations of sulfuric acid and urea in the nitrogen oxide removal liquid within a predetermined range.

On the other hand, the nitrogen oxide reduction device according to an embodiment of the present invention may further include a blower 130 located inside or outside the reactor body 110 in order to smooth the flow of the exhaust gas.

2 is a schematic diagram of a nitrogen oxide reduction apparatus including a plurality of gas-liquid contact units according to another embodiment of the present invention.

Referring to FIG. 2, the nitrogen oxide reduction device 200 may include a plurality of gas-liquid contact units and a liquid supply unit for supplying a nitrogen oxide removal liquid to each gas-liquid contact unit.

Each gas-liquid contact unit has a reactor body 210, a gas inlet 212, a gas-liquid contact 214 and a gas outlet 216, as described with reference to FIG. 1. In addition, the nitrogen oxide reduction device 200 may further include a liquid outlet 218 at the bottom of the reactor body 210. The plurality of gas-liquid contact units are connected to the gas outlet 216 and the gas inlet 212 of the subsequent gas-liquid contact unit to enable continuous processing of the exhaust gas.

Similarly, as described with reference to FIG. 1, the liquid supply unit of the nitrogen oxide abatement device 200 includes a liquid tank 220 that is separate or integral with each reactor body 210. The liquid supply unit includes a liquid supply pump 222 and a liquid supply pipe 224. Nitrogen oxide removal liquid containing sulfuric acid, urea and water contained in the liquid tank 220 is constantly supplied to the gas-liquid contact portion 214 of each gas-liquid contact unit through the liquid supply pump 222 and the liquid supply pipe 224. .

According to embodiments of the present invention, a liquid regeneration unit for regeneration of nitrogen oxide may be connected to the liquid tank 220. In addition, a blower 230 may be installed inside or outside the gas-liquid contact unit to smooth the flow of the exhaust gas.

The exhaust gas treated in the first gas-liquid contact unit can be increased to 98% or more by removing nitrogen oxides through the gas-liquid contact units such as the second and third. At the point 202 where the exhaust gas is introduced through the gas inlet of the first gas-liquid contact unit and at the point 204 where it is discharged to the gas outlet of the last gas-liquid contact unit, a gas concentration meter for measuring the concentration of nitrogen oxides is provided. Can be. Therefore, by comparing the concentration of nitrogen oxides measured at the two points it can be calculated and monitored the removal efficiency of nitrogen oxides.

3 is a flowchart illustrating a method for reducing nitrogen oxides of exhaust gas according to embodiments of the present invention.

Referring to FIG. 3, first, an exhaust gas including nitrogen oxide is introduced into a gas-liquid contact unit including a gas inlet, a gas outlet, and a gas-liquid contact unit (S10). The exhaust gas containing nitrogen oxide includes exhaust gas generated in various industrial facilities, such as generated in a combustion process of fuel in a boiler, incinerator, generator, or the like, or in an etching process of metal or silicon using nitric acid. The gas-liquid contact unit used to remove the nitrogen oxides includes a gas-liquid contact unit which is commonly used, and may be substantially the same as the gas-liquid contact unit of the nitrogen oxide reduction device described with reference to FIGS. 1 and 2.

Subsequently, a nitrogen oxide removal liquid including sulfuric acid, urea and water is supplied to the gas-liquid contact unit (S20). The nitrogen oxide removal liquid may be prepared by mixing an aqueous solution of urea with a predetermined concentration with an aqueous sulfuric acid solution. The nitrogen oxide removal liquid is a concentration of sulfuric acid from about 10 to about 40 w / v% (w / v% is the weight (g) of the component in 100 mL of solution in terms of percent) in consideration of the removal efficiency of the nitrogen oxide, Urea is preferably included at a concentration of about 1 to about 15 w / v%. More preferably, sulfuric acid may be included in a concentration range of about 15 to about 30 w / v% and urea may be included in a concentration range of about 5 to about 10 w / v%.

The nitrogen oxide removal liquid supplied to the gas-liquid contact unit contacts the exhaust gas at the gas-liquid contact portion to remove nitrogen oxides from the exhaust gas (S30). The reaction of the nitrogen oxide contained in the removal liquid and the exhaust gas may be represented by the following formulas (4) and (5).

NO + NO ₂ + 2H ₂ SO ₄ → 2NOHSO ₄ + H ₂ O ...... (4)

2NOHSO ₄ + NH ₂ CONH ₂ → 2N ₂ + CO ₂ + H ₂ O + 2H ₂ SO ₄ ...... (5)

Referring to the formulas (4) and (5), nitrogen oxides such as NO and NO ₂ react with sulfuric acid to produce an intermediate NOHSO ₄ , and NOHSO ₄ is reduced by urea to discharge nitrogen gas and carbon dioxide and again. Produce sulfuric acid. Sulfuric acid in the nitrogen oxide removal liquid is not consumed in theory because it functions as a chemical catalyst, urea is a component consumed in proportion to the throughput of nitrogen oxides. Therefore, in the case of recovering the nitrogen oxide removal liquid in contact with the exhaust gas and reusing it for the treatment of the exhaust gas, a process of adding urea to the removed removal liquid by the consumed amount in order to maintain the concentration of the urea in an appropriate range is additionally performed. Can be performed. In addition, the reaction may be carried out at a low temperature such as room temperature to prevent the reduction of fuel costs and the generation of secondary nitrogen oxides due to the combustion of air.

As described above, the exhaust gas treated with the nitrogen oxide removal liquid and the nitrogen oxide is removed is discharged through the gas outlet of the gas-liquid contact unit (S40).

According to embodiments of the present invention, the removal of nitrogen oxides can be performed in a plurality of gas-liquid contact units. In this case, the exhaust gas which flows into the first gas-liquid contact unit and comes out of contact with the nitrogen oxide removing liquid is discharged into the second gas-liquid contact unit and comes into contact with the nitrogen oxide removing liquid again. While repeating the above process while passing through a plurality of gas-liquid contact units, the concentration of nitrogen oxide contained in the exhaust gas may be drastically reduced to increase the removal rate by 98% or more.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are provided to illustrate the present invention, and the present invention is not limited to the following examples and may be variously modified and changed.

Removal and Evaluation of Nitric Oxide

Example 1

In order to quantitatively generate nitrogen oxides, an aqueous solution containing 50% by weight of NaNO ₂ and excess water was reacted with an excess of 25% aqueous sulfuric acid solution to produce nitrogen oxides according to the following formula (6).

₂ NaNO ₂ + H ₂ SO ₄ → Na ₂ SO ₄ + H ₂ O + NO + NO ₂ ...... (6)

Moreover, the nitrogen oxide reduction apparatus provided with the some gas-liquid contact unit as shown in FIG. 2 was provided. In this embodiment, the apparatus is configured to have four screwer units.

Meanwhile, 5L of 96% sulfuric acid aqueous solution with specific gravity 1.8L, 1.5kg of urea with specific gravity 1.335 and 23.9L of water were mixed, so that the concentration of sulfuric acid dissolved in water was about 30w / v% (w / v% was the component in 100mL of solution). And a weight (g) in percent), and about 30 L of a nitrogen oxide removal liquid having a concentration of urea of about 5 w / v% was prepared. Thus prepared nitrogen oxide removal liquid contained about 25.1 wt% sulfuric acid, 4.4 wt% urea and 70.5 wt% water based on the total weight of the composition. The prepared nitrogen oxide removal liquid was introduced into the liquid tank of the liquid supply unit.

A gas containing nitrogen oxide generated according to Equation (6) is introduced through the gas inlet of the nitrogen oxide reduction device, and the nitrogen oxide removal liquid is supplied through the spray nozzle of the scrubber to induce contact with the gas at room temperature. It was. The nitrogen oxide concentration of the incoming gas was kept constant at about 1,700 ppm. As a result of measuring the concentration of nitrogen oxide discharged through the gas outlet of the fourth screw unit, it was confirmed that the process time was maintained at about 20 ppm or less. Therefore, it was confirmed that the removal rate of nitrogen oxide was maintained at about 98.8% or more.

Stoichiometric evaluation

As discussed above, the theoretical scheme for the removal of nitrogen oxides in Example 1 is as follows.

NO + NO ₂ + 2H ₂ SO ₄ → 2NOHSO ₄ + H ₂ O ...... (4)

2NOHSO ₄ + NH ₂ CONH ₂ → 2N ₂ + CO ₂ + H ₂ O + 2H ₂ SO ₄ ...... (5)

Referring to the above formulas (4), (5) and (6), 2 moles (138 g) of NaNO ₂ produces 1 mole (30 g) of NO and 1 mole (46 g) of NO ₂ , and element 1 for removal thereof. It can be seen that mole (60.06 g) is required. In addition, it can be seen that sulfuric acid contained in the removal liquid acts as a chemical catalyst.

In Example 1, about 6,900 mL (about 50 moles on a NaNO ₂ basis) of 50% of NaNO ₂ was treated using about 1.5 kg (about 24.97 moles) of urea. Given that a small amount of NOx of 20 ppm or less was discharged through the gas outlet and some dissolved in the removal liquid, most of the NOx (25 moles of NO, 25 moles of NO ₂ ) generated from NaNO ₂ contained urea and sulfuric acid according to the above scheme. It was confirmed experimentally that it was removed by an aqueous solution.

Example 2

In order to confirm the appropriate concentrations of sulfuric acid and urea contained in the nitrogen oxide removal liquid, nitrogen oxide removal experiments were performed by changing only the concentrations of sulfuric acid and urea included in the removal liquid in Example 1. The concentration of sulfuric acid was adjusted to 5w / v%, 10w / v%, 15w / v%, 20w / v% and 40w / v% instead of 30w / v% of Example 1, and the concentration of urea was Was adjusted to 1.0w / v%, 2.5w / v%, 10w / v% and 15w / v% instead of 5w / v%.

As a result of the removal of nitrogen oxides, sulfuric acid showed a similar treatment effect in the concentration range of 10w / v% to 40w / v%, and the removal effect of nitrogen oxides was lowered at the concentration below 10w / v%. In the case of urea, the removal effect of nitrogen oxides increased as the concentration increased from 1.0w / v% to 5w / v%, but the removal effect at 5w / v% to 15w / v% was similar. Therefore, it was confirmed that the concentration of sulfuric acid removal liquid is preferably in the range of about 10 to about 40 w / v%, more preferably in the concentration range of about 15 to about 30 w / v%. In addition, in the case of urea, it was confirmed that the concentration range of about 1 to 15 w / v% is preferable, and the concentration range of about 5 to about 10 w / v is more preferable.

Comparative example  One

In order to evaluate the effect of removing nitrogen oxides when treating with pure water, about 25 liters of pure water was used instead of nitrogen oxide removal liquid containing sulfuric acid, urea and water in the nitrogen oxide reduction apparatus used in Example 1 to remove nitrogen oxides. The experiment was performed. The circulation rate of water was adjusted to about 20 L / min and the inlet concentration of the gas was maintained at about 1,688 ppm. Emission concentrations were measured to increase from about 0 ppm initially to about 150 ppm after about 13 minutes.

The removal of nitrogen oxides by water is represented by the following reaction formulas (7) to (9).

2NO ₂ + H ₂ O → HNO ₃ + HNO ₂ ... (7)

2HNO ₂ → NO + NO ₂ + H ₂ O ...... (8)

NO + 1 / 2O ₂ → NO2 ... (9)

That is, NO ₂ reacts with water to produce HNO ₂ and HNO ₃ . HNO ₂ is unstable and decomposes to produce NO and NO ₂ . At this time, the generated NO ₂ reacts with water again to repeat the reaction of Formula (7), but NO is almost not dissolved in water and reacts with oxygen to become NO ₂ , and then repeats the reaction of Formula (7) again. The reactions of (7) and (8) do not proceed completely at higher concentrations of nitric acid (HNO ₃ ) but in pure water. Thus, the first NOx is removed by water, but as the process time elapses, the removal rate is lowered and the removal rate is significantly lowered. In addition, nitric acid absorbed by water has a problem that wastewater treatment for the removal of nitrogen again. In the nitrogen oxide removal experiment, the nitrogen oxide emission concentration increases from about 0 ppm to about 13 minutes afterwards and then to about 150 ppm, indicating that the analysis according to the above reaction equation is valid.

Comparative Example 2

In order to evaluate the effect of removing nitrogen oxides by the aqueous sulfuric acid solution, about 25 liters of 30% sulfuric acid aqueous solution was used instead of nitrogen oxide removal liquid containing sulfuric acid, urea and water in the nitrogen oxide reduction apparatus used in Example 1 to remove nitrogen oxides. The experiment was performed. The inlet concentration of the gas was maintained at about 1,688 ppm and the emission concentration was measured to increase to 150 ppm after about 12 minutes. In other words, the aqueous sulfuric acid solution was found to have a similar ability to remove nitrogen oxides as pure water.

The above-described apparatus and method for reducing nitrogen oxides of exhaust gases of the present invention can remove nitrogen oxides contained in exhaust gases with high efficiency by using a wet solution for removing nitrogen oxides. Therefore, since the expensive solid catalyst used in the conventional selective catalytic reduction method is not used, the facility cost and maintenance costs associated with the use of the solid catalyst can be greatly reduced. In addition, in the above-described method, since nitrogen oxides are removed at a low temperature such as room temperature, fuel costs can be reduced because heat processes such as heating of a reducing agent are not involved, and secondary generation of nitrogen oxides due to combustion of air can be prevented. It can remove nitrogen oxides economically and environmentally.

As described above with reference to the preferred embodiment of the present invention, those skilled in the art without departing from the spirit and scope of the present invention described in the claims below various modifications and It will be appreciated that it can be changed.

1 is a schematic diagram of a nitrogen oxide reduction device having one gas-liquid contact unit according to an embodiment of the present invention.

2 is a schematic diagram of a nitrogen oxide reduction apparatus including a plurality of gas-liquid contact units according to another embodiment of the present invention.

3 is a flowchart illustrating a method for reducing nitrogen oxides of exhaust gas according to embodiments of the present invention.

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

100, 200: nitrogen oxide reduction device

110, 210: reactor body 112, 212: gas inlet

114, 214: gas-liquid contact 116, 216: gas outlet

118, 218: liquid outlet 120, 220: liquid tank

122, 222: liquid supply pump 124, 224: liquid supply pipe

130, 230 blower 140: liquid regeneration unit

Claims (11)

Reactor bodies 110 and 210 having gas-liquid contacts 114 and 214 therein, gas inlets 112 and 212 for introducing exhaust gas containing nitrogen oxides into the reactor body, and the exhaust gas into the reactor body. A gas-liquid contact unit having gas outlets 116 and 216 to discharge therefrom; And A liquid supply unit connected to the gas-liquid contact unit to supply nitrogen gas removal liquids 120 and 220 including sulfuric acid at a concentration of 10 to 40 w / v%, urea at a concentration of 1 to 15 w / v%, and water to the gas-liquid contact unit. Nitrogen oxide reduction apparatus of the exhaust gas comprising a. delete 2. The apparatus of claim 1, wherein the gas-liquid contacting unit further comprises a liquid outlet (118, 218) located below the reactor body and connected with the liquid supply unit. The nitrogen oxide reduction apparatus for exhaust gas according to claim 1, wherein the nitrogen oxide reduction apparatus further includes a blower (130, 230) located inside or outside the gas-liquid contact unit. The nitrogen oxide reduction apparatus for exhaust gas according to claim 1, wherein the nitrogen oxide reduction apparatus further includes a liquid regeneration unit (140) connected to the liquid supply unit and regenerating the nitrogen oxide removal liquid. Contacting the nitrogen oxide removal liquid comprising sulfuric acid at a concentration of 10 to 40 w / v%, urea at a concentration of 1 to 15 w / v%, and water with an exhaust gas containing nitrogen oxides to remove the nitrogen oxides from the exhaust gas. A method for reducing nitrogen oxides in exhaust gas. delete Introducing an exhaust gas containing nitrogen oxide into a gas-liquid contact unit having a gas-liquid contact; Supplying the gas-liquid contact unit with a nitrogen oxide removal liquid comprising sulfuric acid at a concentration of 10 to 40 w / v%, urea at a concentration of 1 to 15 w / v%, and water; Contacting the exhaust gas with the nitrogen oxide removal liquid at the gas-liquid contacting portion to remove the nitrogen oxide from the exhaust gas; And And exhausting the exhaust gas from which the nitrogen oxides have been removed from the gas-liquid contact unit. 9. The method of claim 8, further comprising the step of recovering the nitrogen oxide removal liquid in contact with the exhaust gas and resupplying it to the gas-liquid contact unit. 9. The gas-liquid contact unit is plural, and the exhaust gas discharged from the first gas-liquid contact unit flows into the second gas-liquid contact unit to be in contact with the nitrogen oxide removal liquid containing sulfuric acid, urea and water. A method for reducing nitrogen oxides in exhaust gas. delete

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