CN115996785B - Improved method and device for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas - Google Patents

Improved method and device for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas Download PDF

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CN115996785B
CN115996785B CN202080105160.6A CN202080105160A CN115996785B CN 115996785 B CN115996785 B CN 115996785B CN 202080105160 A CN202080105160 A CN 202080105160A CN 115996785 B CN115996785 B CN 115996785B
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exhaust gas
absorbent
organic acid
nitrogen oxides
desulfurization
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CN115996785A (en
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柳海润
赵相济
尹大盛
石东圭
林泰贤
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Dst Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • B01D47/063—Spray cleaning with two or more jets impinging against each other
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1493—Selection of liquid materials for use as absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/79—Injecting reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/104—Ozone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/816—Sonic or ultrasonic vibration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Environmental & Geological Engineering (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Treating Waste Gases (AREA)

Abstract

The present invention relates to a method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, and more particularly, to a further improved method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas by performing a denitrification process of exhaust gas through a wet process under the same operation conditions as those of a desulfurization process, thereby enabling simultaneous denitrification process and desulfurization process of exhaust gas in one wet process equipment.

Description

Improved method and device for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas
Technical Field
The present invention relates to an improved method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, and more particularly, to a method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, which are further improved wet methods.
Background
When fossil fuel is burned, sulfur in the fuel is oxidized to produce sulfur dioxide as sulfur oxide, and nitrogen component in the fuel is oxidized The air for oxidation or combustion is decomposed at high temperature to inevitably produce Nitrogen Oxides (NO) x ). When sulfur oxide (SO x ) And Nitrogen Oxides (NO) x ) When discharged to the atmosphere, the particles combine with water vapor, inorganic substances, and the like in the air to form fine particles having PM2.5 or less, and become a main atmospheric pollutant that reduces the visible distance and induces cardiopulmonary diseases (non-patent document 0001).
Removal of Sulfur Oxides (SO) in atmospheric pollution discharge equipment using fossil fuels x ) A limestone wet desulfurization apparatus is generally used, but the desulfurization rate is 80% to 90%, and therefore, a part of the amount of produced gas is discharged to the atmosphere.
In addition, for removing nitrogen oxides (NO X ) The most common and effective denitrification method is the Selective Catalytic Reduction (SCR) method, but the denitrification rate is only 70% to 90%, so that 10% to 30% of the production amount is inevitably discharged into the atmosphere. Therefore, in order to improve the quality of the atmospheric environment, development of a technique for further reducing the emission is required.
Generally, an atmospheric pollution control apparatus using fossil fuel is arranged in the order of a selective catalytic reduction method, an electric dust collector, and flue gas desulfurization (Flue gas desulfurization, FGD). The selective catalytic reduction method is to reduce nitrogen oxides to nitrogen (N) by injecting ammonia or urea in a gaseous state 2 ) Is used for removing nitrogen oxides. In the flue gas desulfurization apparatus, a limestone slurry is sprayed to remove sulfur dioxide (SO 2 ) The gas is absorbed by the limestone slurry and oxidized, thereby being converted into solid gypsum (CaSO 4 ) Sulfur dioxide is removed by way of (a) means. However, if the injection amount of the denitrification agent and the desulfurization agent is increased to improve the removal rate, the increased unreacted materials may cause malfunction of the apparatus.
Residual Nitrogen Oxides (NO) which are not removed even when treated by the selective catalytic reduction method x ) Most of them are insoluble Nitric Oxide (NO), and therefore are not removed in the absorber of the flue gas desulfurization apparatus and are inevitably discharged to the atmosphere. For more complete removal, development of a wet method for removing nitrogen oxides by an absorption method in an absorption tower of a flue gas desulfurization apparatus has been requiredAnd (5) denitrification technology.
As a related art, a method for preparing nitrogen oxides by plasma and mixing them with Na is disclosed 2 S、Na 2 SO 3 Methods for removing nitrogen oxides by reaction (patent document 0001 and non-patent document 0002), and methods for removing SO by reaction are disclosed x 、NO x Adsorption in alcohols or glycols as organic solvents to remove SO x 、NO x But these prior arts have the following problems (patent document 0002): in order to simultaneously treat desulfurization and denitrification, further use of expensive Na is required 2 S、Na 2 SO 3 And it is required to additionally prepare a desulfurization and denitrification solution for use as a complex solution comprising polyol and/or polyethylene glycol, and it is required to adjust the temperature of flue gas before desulfurization and denitrification is performed, and there are problems such as treatment of desulfurization wastewater. There is a limit in practical use.
In addition, korean patent No. 10-1724358 discloses the following: a method of oxidizing a flue gas with ozone and then adsorbing the oxidized flue gas in an adsorption tower by droplets produced from hydrogen peroxide. Korean patent No. 10-1724358 discloses a method for electrochemical removal by using a reaction of iron-ethylenediamine tetraacetic acid (Fe-EDTA) and NO. However, these prior arts have problems in that a new process needs to be constructed. Also, a method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas are disclosed in korean patent application No. 10-2019-0042045 (filing date: 2019.04.10).
Even SO, there is still a need to develop a technology of further improved desulfurization and denitrification methods SO that the safety problems and environmental problems accompanying the existing desulfurization process can be solved, while the SO can be further improved without adding equipment x NO and NO x Is not limited, and the simultaneous removal rate of the same is not limited.
Prior art literature
Patent literature
Patent document 0001: korean patent application No. 10-1800517 (publication date: 2017.07.11)
Patent document 0002: korean patent application No. 10-1871197 (publication date: 2017.02.08)
Patent document 0003: korean patent application No. 10-1724358 (publication date: 2017.03.09)
Patent document 0004: korean patent application No. 10-2019-0042045 (date of application: 2019.04.10)
Non-patent literature
Non-patent document 0001: korean society of atmospheric environment, volume 31, phase 2, month 2015, month 4, pages 143-156.
Non-patent document 0002: moo beer Chang, how Ming Lee, feeling Wu & Chi Ren Lai, journal of the society of air and waste management, 54:941-949.
Disclosure of Invention
Problems to be solved by the invention
The main object of the present invention is to provide a further improved method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, which can simultaneously perform a denitrification process and a desulfurization process of exhaust gas by one wet treatment process, and can economically simultaneously treat sulfur oxides and nitrogen oxides without changing equipment for denitrification or adding expensive denitrification additives in the existing wet desulfurization process operated.
Solution for solving the problem
In order to achieve the above object, an integrated embodiment of the present invention provides a method for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, comprising: (a) A step of oxidizing nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone; (b) A step of obtaining an absorbent by mixing an organic acid or an organic acid salt in an alkaline earth metal compound in an aqueous solution state or a slurry state; and (c) a step of performing denitrification and desulfurization of the exhaust gas by bringing the exhaust gas oxidized by the reaction with ozone in the step (a) into contact with the absorbent of the step (b), the step (c) comprising: and (3) carrying out ultrasonic treatment on the absorbent contacted with the exhaust gas.
In a preferred embodiment of the present invention, the alkaline earth metal compound of step (b) is selected from the group consisting of calcium carbonate, calcium hydroxide and mixtures thereof.
In a preferred embodiment of the present invention, the organic acid in the step (b) is selected from the group consisting of RCOOH (r=h or alkyl group having 1 to 18 carbon atoms), dicarboxylic acid having 1 to 20 carbon atoms, and a mixture thereof.
In a preferred embodiment of the present invention, the organic acid or organic acid salt in the step (b) is contained in an amount of 1ppm to 3000ppm based on the solid content in the absorbent.
In a preferred embodiment of the present invention, the step (a) includes: oxidizing Nitric Oxide (NO) contained in the exhaust gas into nitrogen dioxide (NO) by reacting the exhaust gas with ozone 2 ) Is carried out by a method comprising the steps of.
In a preferred embodiment of the present invention, the desulfurization in the step (c) is a desulfurization reaction performed by a reaction between an alkaline earth metal compound in the absorbent and an oxide of sulfur in the exhaust gas. The denitrification in the step (c) is nitrogen dioxide (NO) obtained by reacting an alkaline earth metal sulfite formed by a desulfurization reaction of an alkaline earth metal compound containing an organic acid or an organic acid salt in an absorbent with Nitric Oxide (NO) contained in the exhaust gas in the step (a) with ozone 2 ) To react with nitrogen dioxide (NO 2 ) Conversion to nitrogen (N) 2 ) Is a denitrification reaction of (2).
In another embodiment of the present invention, there is provided an apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, comprising: a gas phase reaction unit that oxidizes nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone; an absorbent storage unit that stores an absorbent obtained by mixing an organic acid or an organic acid salt with an alkaline earth metal compound in an aqueous solution state or a slurry state; a wet reaction unit configured to perform denitrification and desulfurization of exhaust gas containing sulfur oxides and nitrogen oxides by bringing the absorbent in the absorbent storage unit into contact with the exhaust gas oxidized in the gas phase reaction unit; and an energy application unit provided in the wet reaction unit and configured to ultrasonically treat an absorbent in contact with the exhaust gas oxidized in the gas phase reaction unit.
In a preferred embodiment of the present invention, the wet reaction unit includes: a lower storage part for storing the absorbent injected from the absorbent injection nozzle; an absorbent jetting nozzle for jetting an absorbent; and a circulation pipe for conveying the absorbent to the injection nozzle, wherein the absorbent passes through the circulation pipe from the lower storage part and is injected by the injection nozzle, and then moves to the lower storage part again for circulation.
In a preferred embodiment of the present invention, the energy application unit is characterized in that at least one of a lower storage unit and a circulation line provided in the wet reaction unit is subjected to ultrasonic treatment. In this case, the energy application unit is disposed only in the circulation pipe in the wet reaction unit to perform ultrasonic treatment, or disposed only in the lower storage unit in the wet reaction unit to perform ultrasonic treatment, or disposed in both the lower storage unit and the circulation pipe in the wet reaction unit to perform ultrasonic treatment.
In a preferred embodiment of the present invention, the gas phase reaction section is a pipe or a reactor for transporting exhaust gas.
In a preferred embodiment of the present invention, the alkaline earth metal compound in the absorbent storage unit is selected from the group consisting of calcium carbonate, calcium hydroxide, and a mixture thereof.
In another preferred embodiment of the present invention, the organic acid in the absorbent storage unit is selected from the group consisting of RCOOH (r=h or an alkyl group having 1 to 18 carbon atoms), a dicarboxylic acid having 1 to 20 carbon atoms, and a mixture thereof.
In a preferred embodiment of the present invention, the gas phase reaction unit includes the following reaction: oxidizing Nitric Oxide (NO) contained in the exhaust gas into nitrogen dioxide (NO) by reacting the exhaust gas with ozone 2 )。
In a preferred embodiment of the present invention, the desulfurization in the wet reaction section is a desulfurization reaction performed by a reaction between an alkaline earth metal compound in the absorbent and an oxide of sulfur in the exhaust gas. The wet process reaction part is used for denitrification by mixing organic acid or organic acid salt with sulfur oxide of waste gasAn alkaline earth metal sulfite produced by the desulfurization reaction of the alkaline earth metal compound in the absorbent reacts with nitrogen monoxide (NO) and ozone contained in the exhaust gas of the gas phase reaction unit to obtain nitrogen dioxide (NO) 2 ) To react with nitrogen dioxide (NO 2 ) Conversion to nitrogen (N) 2 ) Is a denitrification reaction of (2).
In a preferred embodiment of the present invention, the gas phase reaction section includes a grid-type nozzle for injecting ozone so as to mix the exhaust gas and ozone sufficiently, and the nozzle is provided before the wet reaction section.
In another preferred embodiment of the present invention, the wet reaction unit is an absorber used in a flue gas desulfurization device in a thermal power plant, and the absorber is sprayed with an absorbent supplied from the absorbent storage unit, and the sprayed absorbent is brought into contact with the exhaust gas oxidized in the gas phase reaction unit to denitrify and desulfurize the exhaust gas containing sulfur oxides and nitrogen oxides.
Effects of the invention
According to the present invention, the denitrification process of the exhaust gas is performed by the wet process under the same operation conditions as the desulfurization process, not only the denitrification process and the desulfurization process of the exhaust gas can be simultaneously performed on one wet process equipment (wet flue gas desulfurization device), but also the denitrification and the desulfurization can be performed without changing the equipment for denitrification in the existing wet process, thereby having the effect of further effectively reducing the inefficiency and the side effects occurring when different operation conditions are applied to the denitrification process and the desulfurization process, respectively, while being economical.
In addition, according to the present invention, nitric Oxide (NO) of the exhaust gas having low reactivity is converted into nitrogen dioxide (NO) having high reactivity by ozone 2 ) And an absorbent is obtained by adding an organic acid or an organic acid salt, and when the absorbent is brought into contact with an exhaust gas to perform denitrification and desulfurization, the absorbent in contact with the exhaust gas is subjected to ultrasonic treatment to increase the reaction rate of sulfur oxides in the exhaust gas and the absorbent, and at the same time, an intermediate product of the sulfur oxides produced at this time is used as a stripping agentNitrogen agent, thereby eliminating the need for adding expensive denitrification additives (Na 2 S、Na 2 SO 3 ) Therefore, the method has the effect of realizing high denitrification and desulfurization efficiency of the waste gas.
Drawings
Fig. 1 is a schematic view of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides in exhaust gas according to an embodiment of the present invention.
Fig. 2 is a schematic view of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides in exhaust gas according to another embodiment of the present invention.
Fig. 3 is a block diagram of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides applied to an embodiment of the present invention.
Reference numerals illustrate:
10: a gas phase reaction section;
11: a mass flowmeter;
15: an air duct;
20: an absorbent storage section;
21. 33: a pipe;
22: a storage tank;
23. 32: a stirring unit;
30: a wet reaction section;
31: a wet process reactor;
35: an absorption tower;
40: an energy application unit.
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Generally, the nomenclature used in this specification is that well known and commonly employed in the art.
In the present specification, a certain portion "including" a certain structural element means that other structural elements may be included without excluding other structural elements unless the specifically stated to the contrary.
The present invention relates to a method for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, which comprises the following steps: (a) A step of oxidizing nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone; (b) A step of obtaining an absorbent by mixing an organic acid or an organic acid salt in an alkaline earth metal compound in an aqueous solution state or a slurry state; and (c) a step of performing denitrification and desulfurization of the exhaust gas by contacting the exhaust gas oxidized by the reaction with ozone in the above step (a) with the absorbent of the step (b), the step (c) comprising: and (3) carrying out ultrasonic treatment on the absorbent contacted with the exhaust gas. .
In addition, the present invention relates to an apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, comprising: a gas phase reaction unit that oxidizes nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone; an absorbent storage unit that stores an absorbent obtained by mixing an organic acid or an organic acid salt with an alkaline earth metal compound in an aqueous solution state or a slurry state; a wet reaction unit configured to denitrify and desulphurize exhaust gas containing sulfur oxides and nitrogen oxides by bringing the absorbent in the absorbent storage unit into contact with the exhaust gas oxidized in the gas phase reaction unit; and an energy application unit provided in the wet reaction unit and configured to ultrasonically treat an absorbent in contact with the exhaust gas oxidized in the gas phase reaction unit.
In particular, the method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas according to the present invention relates to a method and apparatus for accomplishing not only desulfurization of sulfur oxides but also denitrification of nitrogen oxides by using a wet desulfurization process for removing sulfur oxides contained in exhaust gas, which can simultaneously perform a denitrification process and a desulfurization process of exhaust gas by one wet treatment process and can simultaneously treat sulfur oxides and nitrogen oxides with economy without changing equipment for denitrification or adding expensive denitrification additives in the existing operating wet desulfurization process.
Hereinafter, a method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas according to the present invention will be described in detail with reference to the accompanying drawings and according to the steps.
Fig. 1 is a schematic view of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides in exhaust gas according to an embodiment of the present invention, fig. 2 is a schematic view of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides in exhaust gas according to another embodiment of the present invention, and fig. 3 is a structural view of an apparatus for simultaneously removing sulfur oxides and nitrogen oxides applied to an embodiment of the present invention.
According to the invention, sulfur Oxides (SO) contained in the exhaust gas are removed simultaneously x ) And Nitrogen Oxides (NO) x ) The device of (1) comprises: a gas phase reaction unit 10, an absorbent storage unit 20, a wet reaction unit 30, and an energy application unit 40.
The gas phase reaction unit 10 is provided between an exhaust gas generation source (not shown) and the wet process reaction unit 30. The exhaust gas discharged from the exhaust gas generating source is supplied to the gas phase reaction section 10, and then supplied to the wet process reaction section 30 through the gas phase reaction section 10.
The gas phase reaction unit 10 reacts the exhaust gas with ozone to react Nitrogen Oxides (NO) contained in the exhaust gas x ) Oxidation is performed [ step (a) ].
Nitrogen Oxides (NO) contained in the exhaust gas x ) Most consists of Nitric Oxide (NO) which is less reactive and soluble and more difficult to wet process. In the present invention, ozone (O) 3 ) To convert Nitric Oxide (NO) in such nitrogen oxides into highly reactive and soluble and wet-treatable nitrogen dioxide (NO) 2 ) Thus, the denitrification treatment in the denitrification process can be performed in the wet reaction section 30 described later, and the effect of the present invention can be improved.
For example, through the above step (a), nitric Oxide (NO) contained in the exhaust gas can be converted into nitrogen dioxide (NO) according to the following reaction formula 1 2 )。
[ reaction type 1 ]
NO(g)+O 3 →NO 2 (g)+O 2
At this time, the exhaust gas and ozone may be injected into the gas phase reaction section 10 by adjusting the flow rate by the mass flowmeter 11 or the like. The gas phase reaction part 10 may use a duct (duct) 15 for transporting exhaust gas, a teflon tube reactor 12, or the like, but is not limited thereto. The gas residence time in the reactor may be changed by changing the length of the reactor using the above-mentioned tube, the gas residence time in the gas phase reaction part may be changed, and the gas residence time in the gas phase reaction part is proportional to the volume of the reactor, and thus may be generally 1 to 30 seconds, preferably may be 2 to 10 seconds, but is not limited thereto.
In the present invention, in order to sufficiently mix the exhaust gas and ozone, the gas phase reaction unit 10 includes a grid nozzle (not shown) for injecting ozone, and as shown in fig. 1, the nozzle is provided in a step preceding the wet reaction unit.
Wherein the reaction conditions in the gas phase reaction section 10 are 160 ℃ or less, and the exhaust gas and ozone are preferably reacted at 130 ℃ or less. Since the molar ratio of ozone to nitrogen oxide reacts with nitrogen oxide in an equivalent manner, ozone may be injected in an equivalent amount in order to remove nitrogen oxide. If an excessive amount of ozone is used, ozone is discharged to the atmosphere to cause pollution, and therefore, the equivalent ratio of ozone to nitrogen oxides is preferably 1 or less.
On the one hand, the absorbent storage section 20 stores an absorbent obtained by mixing an organic acid or an organic acid salt with an alkaline earth metal compound in an aqueous solution state or a slurry state, and supplies the stored absorbent to the wet reaction section 30 where denitrification and desulfurization are performed [ step b ].
The absorbent storage unit 20 may be connected to the wet reaction unit through a connection pipe 21. The above-described connection pipe 21 has one side connected to the absorbent storage part 20 and the other side connected to the wet reaction part 30, so that the absorbent stored in the absorbent storage part 20 can be supplied to the wet reaction part 30 through the connection pipe, and may further include a pump, a valve, etc. for use therein.
The above-mentioned absorbent can be prepared by mixing an organic acid or an organic acid salt with an alkaline earth metal compound in the form of an aqueous solution or slurry in which the alkaline earth metal compound is dispersed in water. In this case, the above-mentioned mixing can be easily performed by a method used in the art.
The alkaline earth metal compound may be one or more selected from the group consisting of calcium carbonate and calcium hydroxide, and calcium carbonate is preferable in terms of treatment cost and practicality.
In one aspect, the organic acid is selected from the group consisting of RCOOH (r=h or alkyl of 1 to 18 carbon atoms), dicarboxylic acids of 1 to 20 carbon atoms, and mixtures thereof, preferably formic acid, and the organic acid salt is preferably an alkaline earth metal salt of formic acid.
The absorbent of the present invention as described above is prepared by mixing an organic acid or an organic acid salt with an alkaline earth metal compound, and the ion exchange reaction by the organic acid is carried out on the surface of the alkaline earth metal compound, so that the surface of the alkaline earth metal compound is continuously consumed, and the particle size of the absorbent can be made smaller.
This principle is very similar to CMP of semiconductor processes and the etching rate of the calcium carbonate surface depends on the acid content and the degree of particle movement. Although the higher the acid content or the greater the particle movement, the smaller the particle size, it is sufficient to determine its extent on the COD and cost limits of the wastewater.
In addition, the solubility of alkaline earth metal compounds in water is generally very low, and thus has a problem of very low reactivity with sulfur oxides and nitrogen oxides caused in an aqueous phase. This problem can be solved by adding an organic acid because an alkali metal salt such as a calcium salt that enhances water solubility can be formed by the reaction of an alkaline earth metal compound with the organic acid. That is, since sulfur oxides can only react with calcium in the aqueous phase, the higher the concentration of calcium salt soluble in water in the wet process, the more calcium ions come into contact with sulfur oxides and sulfur oxides can be effectively removed.
In particular, when formic acid is used as the above-mentioned organic acid, a sufficient effect can be obtained with a smaller amount of the organic acid due to the lower molecular weight of formic acid, and corrosion and/or erosion in the device can be prevented while minimizing the increase in COD.
In general, in order to promote removal of sulfur oxides in exhaust gas, a considerable amount of dibasic acid (dibasic acid) or the like needs to be continuously added to maintain a sufficient concentration in a liquid phase, but it is known that such an excessive amount of dibasic acid or the like can promote corrosion and/or erosion in the apparatus over a long period of time, and further COD problems may occur. That is, when COD is increased, there is a disadvantage in that the wastewater process needs to be performed again to remove it.
However, formic acid has a half carbon number of dibasic acid and excellent physicochemical properties of water solubility compared with dibasic acid, so that the particle size of the absorbent can be greatly reduced when it is mixed with the absorbent. In addition, by producing an alkali metal salt having improved solubility, not only desulfurization and denitrification efficiency can be improved, but also safety problems and environmental problems in the conventional desulfurization and denitrification processes to which dibasic acids are applied as organic acids can be solved.
Specifically, in the present invention, when the carbon number-containing catalyst is a dibasic acid (e.g., HOOC-CH 2 -CH 2 -COOH) as an additive, not only an alkali metal salt excellent in water solubility can be produced, but also the reactivity and absorptivity of sulfur oxides and nitrogen oxides in exhaust gas can be further improved as the surface of the absorbent is consumed by the ion exchange reaction with the surface of the alkaline earth metal compound, and the particle size of the absorbent becomes smaller.
In the present invention, the organic acid or organic acid salt contained in the absorbent is 1ppm to 3000ppm, preferably 10ppm to 2000ppm, relative to the solid content of the absorbent.
If the organic acid or organic acid salt is mixed so as to be less than 1ppm relative to the solid component of the absorbent, the effect of mixing the organic acid or organic acid salt cannot be exerted, and if it exceeds 3000ppm, the cost increases and problems such as COD and corrosion may occur.
In the present invention, in order to promote dissolution of calcium in the absorbent and further promote desulfurization and denitrification, the absorbent containing the above-mentioned organic acid may include, in addition to formic acid, an additional organic acid including an organic acid containing only carboxyl groups such as acetic acid, propionic acid, butyl carboxylic acid, amyl carboxylic acid, adipic acid, succinic acid, maleic acid, malic acid, and the like; or an organic acid containing both carboxyl and hydroxyl groups, such as 3-hydroxy-propionic acid (3-hydroxy-propionic acid), hydroxy-acetic acid (hydroxy-acetic acid), and the like. Wherein the organic acid containing both carboxyl and hydroxyl groups may be a polymer or a single molecule.
The absorbent storage unit 20 may include a storage tank 22 and a stirring unit 23. The storage tank 22 for storing the absorbent may store the absorbent in an aqueous solution state or a slurry state. The storage tank 22 may be connected to the wet reaction section 30 through a connection pipe 21.
The stirring unit 23 provided in the storage tank 22 stirs the absorbent stored in the storage tank 22 to be uniform, thereby promoting the reaction between the organic acid or the organic acid salt and the alkaline earth metal compound.
As described above, the absorbent in the absorbent storage part 20 and the exhaust gas oxidized in the gas phase reaction part 10 are supplied to the wet reaction part 30, and the exhaust gas supplied to the above wet reaction part 30 is contacted with the absorbent in the wet reaction part, thereby performing denitrification and desulfurization of the exhaust gas [ step (c) ].
In the wet reaction section 30, desulfurization is performed by a reaction between the sulfur oxide of the exhaust gas and the alkaline earth metal compound in the absorbent; by alkaline earth metal sulphites (SO 3 ) And nitrogen dioxide generated by oxidizing and absorbing nitrogen monoxide in the exhaust gas, wherein the alkaline earth metal sulfite is an intermediate product generated by a desulfurization reaction between an oxide of sulfur in the exhaust gas and an alkaline earth metal compound in the absorbent.
In one example, desulfurization in the wet reaction section 30 is achieved by: in passing the sulfur oxides of the exhaust gas through the liquid phase reactor or through the absorption tower of the flue gas desulfurization device at a thermal power plant or the like, the sulfur oxides are absorbed in the injected limestone slurry.
On the one hand, the composition will contain calcium carbonate (CaCO) 3 ) In the case where the absorbent is supplied from the absorbent storage section to the wet reaction section, desulfurization and denitrification reactions can be performed according to the following equations 2 to 7.
[ reaction type 2 ]
(parallel reaction, slow reaction)
[ reaction type 3 ]
CaCO 3 (s)+2H + →Ca 2+ +H 2 O+CO 2 (g) (slow)
[ reaction type 4 ]
CaCO 3 (s)+2RCOOH(l)→Ca(RCOO) 2 (l)+H 2 O+CO 2 (fast)
[ reaction type 5 ]
Ca(RCOO) 2 (l)+2H + →Ca 2+ +2RCOOH (l) (fast)
[ reaction type 6 ]
Ca 2+ +SO 3 2- (l)→CaSO 3 (S) (fast)
[ reaction type 7 ]
CaSO 3 (s)+1/2NO 2 →CaSO 4 (s)+1/4N 2 (fast)
As shown in the above equations 2 to 7, sulfur dioxide (SO) in the exhaust gas supplied from the gas phase reaction section 10 2 ) Reacts with water in the absorbent to generate hydrogen ions and sulfite ions, and the generated hydrogen ions (protons) react with calcium carbonate of the absorbent to generate calcium ions. However, the reaction rate of calcium ions generated therein is slow, and thus the completeness of desulfurization and denitrification reactions is limited.
Thus, as in the present invention, when an organic acid or an organic acid salt is added, calcium ions can be rapidly generated according to equations 4 and 5. The calcium ions generated in this way react with the previously generated sulfite ions according to equation 6 to generate calcium sulfite (CaSO 3 ). The calcium sulfite produced at this time is identical to the calcium sulfite produced beforeThe nitrogen dioxide generated in the gas phase reaction section is reacted to change the calcium sulfite into calcium sulfate, and the nitrogen dioxide is converted into nitrogen to perform a denitrification reaction.
On the one hand, the desulfurization is carried out by passing sulfur dioxide contained in the exhaust gas through sulfite ions (SO 3 2- ) The final conversion to calcium sulfate (calcium salt) is achieved and is thereby removed from the exhaust gas.
That is, as shown in reaction formula 7, calcium sulfite (CaSO) produced by desulfurization of sulfur dioxide 3 ) Is used as a reducing agent for nitrogen oxides and is produced by the above-mentioned calcium sulfite (CaSO 3 ) Reaction with nitrogen dioxide to produce nitrogen (N) 2 ) And calcium sulfate (CaSO) 4 ). Therefore, the method of the present invention is characterized in that, in the case where an organic acid is contained in calcium carbonate, such calcium sulfite that can be produced by desulfurization reaction can be reacted more rapidly, and in this case, in the case of the above-mentioned ultrasonic treatment, the reaction can be performed more effectively, and the above-mentioned calcium sulfite is used for denitrification, and therefore, nitrogen dioxide in exhaust gas is converted into nitrogen (N 2 ) Is removed from the exhaust gas.
As a result, the organic acid or organic acid salt mixed in the absorbent not only absorbs sulfur oxide but also enhances absorption of nitrogen oxide, and at the same time, the reaction rate of the slow reactions of equations 2 and 3 can be accelerated by the catalytic action of equations 4 to 5, as a result, the organic acid or organic acid salt generates more calcium sulfite (CaSO 3 ) Can play a decisive role.
In this case, in order to increase the denitrification efficiency of the exhaust gas, it is necessary to increase the concentration of calcium sulfite as a reducing agent. For this purpose, it is necessary to increase the desulfurization rate, and therefore, in the present invention, expensive denitrification additives (Na 2 S、Na 2 SO 3 Etc.), but the nitrogen removal and desulfurization efficiency of the exhaust gas can be maximized by using an absorbent mixed with an organic acid or an organic acid salt in the case of applying energy.
In one aspect, the energy application unit of the present invention is provided in the wet reaction unit 30, and can ultrasonically treat the absorbent contacted with the exhaust gas oxidized in the gas phase reaction unit. The energy application unit 40 is not limited to a device that can be attached or connected to the inside or outside of the wet reaction unit 30 or combined with the inside or outside of the wet reaction unit 30 to apply ultrasonic waves to the wet reaction unit.
Among them, the power (W) of the ultrasonic wave applied from the above-mentioned energy application part 40 should be applied in proportion to the scale of the wet reaction part, and thus it is difficult to limit or specify the range, and the vibration frequency thereof is generally applied in the range of 2kHz to 2000kHz, preferably in the range of 10kHz to 400kHz, more preferably in the range of 20kHz to 40kHz, but is not limited thereto.
Also, the wet reaction part 30 according to the present invention may include a wet reactor 31 and a stirring unit 32. As described above, sulfur oxides and nitrogen oxides are absorbed by limestone slurry injected during passage through the absorption tower 35 of a flue gas desulfurization apparatus at a thermal power plant or the like, and thus desulfurization and denitrification can be performed simultaneously.
That is, the wet reaction unit includes: a lower storage part for storing the absorbent injected from the absorbent injection nozzle; an absorbent jetting nozzle for jetting an absorbent; and a circulation pipe for conveying the absorbent to the injection nozzle, wherein the absorbent may be configured to circulate by moving again to the lower storage part after passing through the circulation pipe and being injected by the injection nozzle. In this case, the energy application unit may be provided only in a circulation pipe in the wet reaction unit to perform ultrasonic treatment, or may be provided only in a lower storage unit in the wet reaction unit to perform ultrasonic treatment; or the lower storage part and the circulating pipeline which are arranged in the wet reaction part can be simultaneously used for respectively carrying out ultrasonic treatment.
The above-described matters can be described in detail with reference to fig. 2, and fig. 2 shows a specific example in which the desulfurization reaction and the denitrification reaction according to the present invention can be performed in a flue gas desulfurization apparatus in a conventional thermal power plant. As a means corresponding to the above-mentioned gas phase reaction section in the present invention, a means for transporting waste is used The exhaust gas of the gas is conveyed by the air duct. Ozone generated from the ozone generating part in the air duct and Nitrogen Oxides (NO) x ) In particular Nitric Oxide (NO), to convert said nitric oxide into nitrogen dioxide (NO) 2 ) And the oxidation reaction product of nitrogen oxides by the above ozone [ comprising nitrogen dioxide (NO 2 ) Passes through an absorber 35 in an existing flue gas desulfurization apparatus. The slurry supplied from the absorbent storage unit 20 in the absorber is sprayed upward or downward, and as a result, the sprayed liquid falls downward by gravity, wherein the absorbent storage unit 20 contains limestone slurry used for the conventional desulfurization reaction. At this time, the injected slurry reacts with the oxidation reaction product of nitrogen oxides by the ozone [ comprising nitrogen dioxide (NO 2 ) The reaction is performed, and thus, an apparatus for simultaneously performing desulfurization and denitrification is shown in fig. 2.
That is, the wet reaction section in the present invention corresponds to an absorption tower used in a flue gas desulfurization apparatus in a thermal power plant, and the desulfurization and denitrification apparatus may be configured by injecting the absorbent of the present invention supplied from the absorbent storage section into the absorption tower so that the injected absorbent contacts the exhaust gas oxidized from the gas reaction section according to the present invention, thereby denitrifying and desulfurizing the exhaust gas containing sulfur oxides and nitrogen oxides. The energy application unit is provided only in a circulation pipe in the wet reaction unit (absorption tower) to perform ultrasonic treatment, or is provided only in a lower storage unit in the wet reaction unit (absorption tower) to perform ultrasonic treatment, or is provided in both the lower storage unit and the circulation pipe in the wet reaction unit (absorption tower) to perform ultrasonic treatment, respectively. As a result, the desulfurization and denitrification apparatus may be provided with an apparatus for applying ultrasonic waves to the absorbent in contact with the exhaust gas circulating in the wet reaction section (absorption tower) to thereby improve the denitrification and desulfurization efficiency.
Accordingly, the present invention uses the slurry injection device and the exhaust gas transfer duct in the absorber, which are used in the prior art, as the gas phase reaction part, and the exhaust gas transfer duct is further utilized in the oxidation reaction with ozone. Further, by adding only the alkaline earth metal compound in the form of an aqueous solution or slurry to the absorbent storage unit, mixing the alkaline earth metal compound with an organic acid or organic acid salt, and using the mixture as an absorbent, and applying ultrasonic waves to the wet reaction unit, it is possible to achieve the excellent effect that the desulfurization reaction and the denitrification reaction can be further performed in addition to the desulfurization reaction alone in the conventional absorption tower, and the respective reaction efficiencies of the desulfurization reaction and the denitrification reaction can be further improved.
On the other hand, in the case where the above-mentioned wet reactor according to the present invention includes the wet reactor 31 and the stirring unit 32 instead of the absorption tower system at the place of the thermal power generation station of the related art or the like, there may be formed: each inflow port (not shown) through which the absorbent and the exhaust gas can flow, respectively; a reaction unit (not shown) in which denitrification and desulfurization of the absorbent and the exhaust gas can be performed; a discharge port for discharging the denitrification and desulfurization products; and an energy generating unit (not shown) for applying ultrasonic waves to the reaction unit. Further, since the stirring unit 32 is provided in the wet reactor 31, the absorbent and the exhaust gas supplied to the wet reactor are stirred to promote denitrification and desulfurization of the exhaust gas. In this case, the stirring unit 32 may be used without limitation as long as it is a member for improving the gas-liquid contact efficiency between the absorbent and the exhaust gas; the stirring unit 32 may be a stirrer, a bubble generator (bubble generator), or the like.
After that, the above exhaust gas is discharged to the outside through the connection duct 33 after removing nitrogen oxides and sulfur oxides by desulfurization and denitrification processes in the wet reaction part. At this time, the alkali metal salt generated in the wet reaction section remains in the wet reaction section in the form of an aqueous solution or slurry, and can be recovered for use by obtaining calcium sulfate (gypsum) or discharging to a treatment facility (not shown).
According to the improved method and apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas of the present invention, nitrogen dioxide having a relatively low reactivity is converted into nitrogen dioxide having a relatively high reactivity by reaction with ozone, and then, in the case of denitrifying and desulfurizing exhaust gas by bringing exhaust gas oxidized by reaction with ozone into contact with an absorbent obtained by mixing an organic acid or an organic acid salt, the denitrification reaction is induced with further improved efficiency by the above-mentioned ultrasonic treatment, whereby by supplying the absorbent in an aqueous solution state or a slurry state containing an organic acid or an organic acid salt to perform a denitrification process in parallel under the same conditions as a desulfurization process, inefficiency and side effects occurring when different operation conditions are applied to the denitrification process and the desulfurization process, respectively, can be reduced, and residual nitrogen oxides which cannot be removed in a selective catalytic reduction apparatus can be effectively removed while improving desulfurization performance more than in the prior art by applying the existing wet desulfurization apparatus by applying the original place without adding expensive denitrification additives.
Hereinafter, the present invention will be described more specifically by way of examples of the present invention. However, the following embodiment is merely an example of the present invention, and the scope of the present invention is not limited to the following embodiment.
< examples 1 to 2>
Waste gas of Korean coal thermal power stations A (example 1) and B (example 2) was sampled, and an equal amount of 14ppm ozone was injected into a waste gas sampling line having a length of 10m, and nitrogen monoxide (NO) was converted into nitrogen dioxide (NO) by measuring 2 ) And is shown in table 1.
TABLE 1
Partitioning NO(ppm) NO 2 (ppm) Conversion (%)
Example 1 14 14 100
Example 2 25 25 100
As shown in table 1, it was confirmed that the oxidation reaction of nitric oxide by ozone completely converted nitric oxide into nitrogen dioxide.
< examples 3 to 8>
The flue gas containing nitrogen oxides and sulfur oxides is subjected to denitrification and desulfurization using the apparatus shown in fig. 2.
First, a mass flow meter was used to obtain a mixture containing 13ppm of Nitric Oxide (NO) and 425ppm of sulfur dioxide (SO 2 ) Is mixed with 4.5g/m of waste gas 3 Ozone of 4.8m 3 And/hr is injected into the gas phase reaction part 10. The molar ratio of ozone to nitric oxide is equivalent ratio.
The exhaust gas and ozone remain in the gas phase reaction section for 6 seconds, and the exhaust gas is oxidized by reaction with ozone at normal temperature and normal pressure. The oxidized waste gas is in a volume of 4.8m 3 The sample/hr was supplied to the wet reaction section 30, and in the case of ultrasonic (20 kHz) treatment, the sample was reacted with an absorbent, and the removal rates of nitrogen oxides and sulfur oxides were measured by a combustible gas detector (testo 350), and are shown in table 2.
At this time, an absorbent was prepared by adding the organic acid and the content of table 2 to the calcium carbonate slurry of 20% solid content, and the absorbent prepared above was supplied to the wet reaction section (100L) in a volume of 50L. In this case, the above-mentioned absorbent used an absorbent which passes 325 mesh at 90%.
Comparative examples 1 to 2 ]
The nitrogen oxides and sulfur oxides contained in the exhaust gas were removed by the same method as in example 3, and the nitrogen oxides and sulfur oxides of the exhaust gas were removed by the conditions of table 2, and the removal rates of the nitrogen oxides and sulfur oxides were measured using a flammable gas detector (testo 350) and are shown in table 2.
Comparative example 3 ]
The nitrogen oxides and sulfur oxides contained in the exhaust gas were removed by the same method as in example 4, the exhaust gas was reacted without ultrasonic irradiation to remove the nitrogen oxides and sulfur oxides of the exhaust gas, and the removal rates of the nitrogen oxides and sulfur oxides were measured using a flammable gas detector (testo 350) and are shown in table 2.
TABLE 2
As shown in table 2 above, it was confirmed that the removal rates of nitrogen oxides and sulfur oxides in examples 3 to 8 were far higher than those in comparative examples 1 to 3, and in particular, example 3 showed the nitrogen oxide removal rate improved by the ultrasonic treatment compared to comparative example 1, and examples 4 and 6 showed the nitrogen oxide removal rate improved by the ultrasonic treatment compared to comparative example 3.
The specific parts of the present invention have been described in detail above, and are not limited to what is illustrated in the accompanying drawings, but it is obvious to those skilled in the art that the above-described specific techniques are merely preferred embodiments, and the scope of the present invention is not limited thereto. Therefore, the actual scope of the invention should be defined by the appended claims and equivalents thereof.
Industrial applicability
The present invention relates to a further improved method and apparatus for removing sulfur oxides and nitrogen oxides contained in exhaust gas by performing a denitrification process of exhaust gas by a wet process under the same operation conditions as a desulfurization process, thereby enabling simultaneous denitrification process and desulfurization process of exhaust gas in one wet process equipment, and thus having industrial applicability.

Claims (12)

1. A method for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, comprising:
a step (a) of oxidizing nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone;
a step (b) of obtaining an absorbent by mixing an organic acid or an organic acid salt in an alkaline earth metal compound in an aqueous solution state or a slurry state; and
a step (c) of performing denitrification and desulfurization of the exhaust gas by contacting the exhaust gas oxidized by the reaction with ozone in the step (a) with the absorbent of the step (b),
the desulfurization in the step (c) is a desulfurization reaction performed by a reaction of sulfur oxides of exhaust gas and alkaline earth metal compounds in the absorbent,
the denitrification in the step (c) is nitrogen dioxide (NO) obtained by reacting an alkaline earth metal sulfite with Nitric Oxide (NO) contained in the exhaust gas with ozone in the step (a) 2 ) Nitrogen dioxide (NO) 2 ) Conversion to nitrogen (N) 2 ) Wherein the alkaline earth metal sulfite is produced by desulfurization of an alkaline earth metal compound in which an organic acid or an organic acid salt is mixed in an absorbent with a sulfur oxide of an exhaust gas,
Said step (c) comprises: a step of subjecting the absorbent contacted with the exhaust gas to ultrasonic treatment,
the alkaline earth metal compound of step (b) is selected from the group consisting of calcium carbonate, calcium hydroxide and mixtures thereof,
the organic acid or organic acid salt in the step (b) is contained in an amount of 1ppm to 3000ppm based on the solid content in the absorbent.
2. A method for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 1,
the organic acid of step (b) is selected from the group consisting of RCOOH, a dicarboxylic acid having 1 to 20 carbon atoms, and mixtures thereof; wherein R in RCOOH is H or alkyl with 1-18 carbon atoms.
3. An apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas, comprising:
a gas phase reaction unit that oxidizes nitrogen oxides contained in the exhaust gas by reacting the exhaust gas with ozone;
an absorbent storage unit that stores an absorbent obtained by mixing an organic acid or an organic acid salt with an alkaline earth metal compound in an aqueous solution state or a slurry state;
a wet reaction section for denitrifying and desulfurizing exhaust gas containing sulfur oxides and nitrogen oxides by bringing the absorbent in the absorbent storage section into contact with the exhaust gas oxidized in the gas phase reaction section; and
An energy application unit provided in the wet reaction unit and configured to ultrasonically treat an absorbent in contact with the exhaust gas oxidized in the gas phase reaction unit,
the desulfurization in the wet reaction section is a desulfurization reaction performed by a reaction of an alkaline earth metal compound in the absorbent with an oxide of sulfur of the exhaust gas,
the denitrification in the wet reaction section is nitrogen dioxide (NO) obtained by reacting alkaline earth metal sulfite with Nitric Oxide (NO) contained in the exhaust gas and ozone in the gas phase reaction section 2 ) Nitrogen dioxide (NO) 2 ) Conversion to nitrogen (N) 2 ) Wherein the alkaline earth metal sulfite is produced by desulfurization of an alkaline earth metal compound in an absorbent of a mixed organic acid or organic acid salt with a sulfur oxide of exhaust gas,
the alkaline earth metal compound is selected from the group consisting of calcium carbonate, calcium hydroxide, and mixtures thereof,
the content of the organic acid or organic acid salt is 1ppm to 3000ppm relative to the solid content in the absorbent.
4. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the wet reaction section includes:
A lower storage part for storing the absorbent injected from the absorbent injection nozzle;
an absorbent jetting nozzle for jetting an absorbent; and
a circulation pipe for feeding the absorbent to the injection nozzle,
the absorbent passes through the circulation pipe from the lower storage portion and is sprayed from the spray nozzle, and then moves to the lower storage portion again to circulate.
5. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the energy application unit is provided in at least one of a lower storage unit and a circulation pipe in the wet reaction unit, and performs ultrasonic treatment.
6. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 5, wherein,
the energy application unit is provided only in the circulation pipe in the wet reaction unit to perform ultrasonic treatment.
7. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 5, wherein,
the energy application unit is provided only in a lower storage unit in the wet reaction unit, and performs ultrasonic treatment.
8. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 5, wherein,
The energy applying part is simultaneously arranged at a lower storage part and a circulating pipeline in the wet reaction part to respectively carry out ultrasonic treatment.
9. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the gas phase reaction part is an air duct or a reactor for conveying waste gas.
10. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the organic acid is selected from the group consisting of RCOOH, a dicarboxylic acid having 1 to 20 carbon atoms, and mixtures thereof; wherein R in RCOOH is H or alkyl with 1-18 carbon atoms.
11. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the gas phase reaction part includes a grid-type nozzle for injecting ozone for sufficiently mixing exhaust gas and ozone, the nozzle being disposed at a step before the wet reaction part.
12. The apparatus for simultaneously removing sulfur oxides and nitrogen oxides contained in exhaust gas as claimed in claim 3, wherein,
the wet reaction section is an absorption tower used in a flue gas desulfurization apparatus in a thermal power plant, and the absorber supplied from the absorber storage section is injected into the absorption tower, and the injected absorber contacts the exhaust gas oxidized in the gas phase reaction section, thereby denitrifying and desulfurizing the exhaust gas containing sulfur oxides and nitrogen oxides.
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