KR101702831B1 - Abatement of Nitrogen Oxides and Sulfur Oxides - Google Patents

Abstract

The present invention relates to a method and an apparatus for removing nitrogen oxide, which enable nitrogen oxide to be quickly removed at a high rate by using an aqueous solution of sodium chlorite (NaClO_2), which is highly stable at room temperature and easy to handle, instead of using highly reactive chlorine dioxide (ClO_2). The apparatus for removing nitrogen oxide according to the present invention comprises: an ultrasonic atomizer configured to atomize acidified liquid sodium chlorite as a reactant solution; a vapor-phase reaction chamber configured to mix the atomized reactant solution with a sulfur-containing nitrogen oxide stream and to allow the mixture to stay therein; an absorber located above the vapor-phase reaction chamber so as to absorb nitrogen oxide from the mixture moving upward from the vapor-phase reaction chamber.

Description

Removal of Nitrogen Oxides and Sulfur Oxides {

The present invention in particular, a highly reactive chlorine dioxide (ClO ₂₎ instead of sodium chlorite with easy high stability treated at room temperature on the removal method, and a nitrogen oxide removal equipment for removing nitrogen oxides and sulfur oxides (NaClO ₂₎ To a removal method and a removal device for removal of nitrogen oxides and sulfur oxides, which makes it possible to remove nitrogen oxides by using an aqueous solution and to remove nitrogen oxides with a rapid and high removal rate.

Nitrogen oxide (NOx) is a pollutant that mainly monoxide was ilkeol nitrogen (NO) and nitrogen dioxide (NO _2), to be a cause of acid rain and mist, it should be removed from the exhaust bath such as gloss or high temperature furnace of the metal. Nitrogen oxides are also referred to as representative pollutants contained in combustion exhausts that are released after combustion of fossil fuels such as petroleum or coal with sulfur dioxide.

Sulfur oxides (SOx) generally refer to sulfur oxides combined with sulfur. However, sulfur dioxide (SO ₂ ), sulfur trioxide (SO ₃ ) and sulfuric acid mist are included in the soot in terms of environmental and piracy aspects. Sulfur dioxide and sulfur trioxide are the main causes of combustion of fossil fuels. They are included in combustion exhausts such as smelters, thermal power plants, sulfuric acid manufacturing plants, various plants and homes using Bunker-C and briquettes as fuel, and automobile exhaust. They are referred to as representative pollutants.

When sulfur dioxide released into the atmosphere or absorbed from the pores of plant leaves is absorbed, it inhibits enzymatic action, inhibits various metabolism, decomposes and binds to internal components, and particularly destroys cells and tissues such as chlorophyll, Causing a sulphurization phenomenon in part or in whole. Atmospheric sulfur dioxide is converted into sulfuric acid through catalytic oxidation and photooxidation process, and is present in gas phase and liquid phase. It is attached to the surface of aerosol type solid particulate, which is the cause of acid rain and acidification of soil and dissolution of nutrients Forest damage occurs, and lake water and so on are acidified, resulting in a decrease in fish and shellfish and contamination by heavy metal leaching. In addition, there are many damages to natural and living environment such as fading of textile products, corrosion of metal, destruction of cultural property and various structures.

Various methods have been studied to remove such nitrogen oxides and sulfur oxides. It is to be understood that nitrogen oxides and sulfur oxides are similar in terms of generation and elimination, and thus, the following description is based on nitrogen oxides but sulfur oxides can also be treated together without being otherwise indicated. In the following, the term "nitrogen oxides and sulfur oxides" should be understood to mean that they can selectively treat either or both of nitrogen oxides and sulfur oxides.

Nitrogen oxides can be easily removed by absorbing with a reducing agent solution, but it is known that the oxidation absorption method is more advantageous because of the problem of increasing the chemical oxygen demand (COD) of the treatment solution. Various oxidizing agents for use in the oxidation absorption method can be mentioned. Examples of the oxidizing agent that can be used include ozone, chlorine dioxide, sulfur, oxygen, and the like applicable to the gas phase reaction, and KMnO ₄ , NaClO ₂ , H ₂ O _2, and ferrous chelate, Compounds and the like. In general, an additive is added to an absorbent cleaning device to oxidize nitrogen oxides (NO) to nitrogen dioxide (NO ₂ ), which is relatively easy to absorb and absorb, and then absorbed with an alkali solution to be removed.

Republic of Korea Patent Application Registration No. 10-0622990 call (title of the invention: the method of removing sulfur dioxide and nitrogen oxides in exhaust gas using chlorine dioxide) is the combustion air sulfur dioxide with chlorine dioxide (ClO _2), (SO ₂₎ and nitrogen More particularly, the present invention relates to a method for removing sulfur dioxide and nitrogen oxides in a combustion exhaust capable of simultaneously removing sulfur dioxide and nitrogen oxides in a combustion exhaust by reacting chlorine dioxide with an alkali solution in an alkali solution. Here, in the removal of sulfur dioxide and nitrogen oxide in the combustion exhaust gas using chlorine dioxide, chlorine dioxide is reacted with the combustion gas in the alkali solution to remove sulfur dioxide and nitrogen oxide in the combustion exhaust, The present invention provides a method for removing nitrogen oxides, Chlorine dioxide is produced by a side reaction when sulfur dioxide and nitrogen oxide are simultaneously removed from the combustion exhaust, and chlorine dioxide produced in this way can be used to remove sulfur dioxide and nitrogen oxides in the combustion exhaust of the present invention.

Chlorine dioxide is a compound of chlorine and oxygen and exists as a reddish yellow gas with odor similar to chlorine or ozone at room temperature. It acts as a strong oxidant, but is extremely unstable to heat, and when heated it decomposes into oxygen and chlorine. It also decomposes by light. In this case, it produces chlorine trioxide in addition to oxygen and chlorine. When water is present, chlorine trioxide, hypochlorous acid, chlorous acid, chloric acid, and perchloric acid are produced. A mixture with hydrogen will explode when heated and will explode when in contact with sulfur, phosphorus, sulfides, etc. It reacts with mercury and ammonia but is absorbed without reacting with sulfuric acid. It is very well dissolved in water to give a yellowish brown aqueous solution. The aqueous solution is stable in the dark but is decomposed by light to produce hydrochloric acid and chloric acid. In addition, when inhaled, it gives severe irritation to the airway. It can cause bronchospasm or pulmonary edema, and can cause severe headache. Symptoms do not appear immediately, and last for a long time. Chronic bronchitis can occur if exposed for long periods of time. Severe irritation to the skin and eyes may occur, especially when the eyes are exposed, such as visible light.

Therefore, even though the reaction rate is fast and the nitrogen oxide removal efficiency is good, the chlorine dioxide itself is difficult to handle and unstable, so attention must be paid to its storage and use. In addition, when chlorine dioxide is exposed, Therefore, there is still a need to develop a removal method and a removal device for the removal of new nitrogen oxides and sulfur oxides that are more stable, faster and capable of removing high nitrogen oxides and sulfur oxides.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art and to develop a new nitrogen oxide and sulfur oxide removal method and apparatus for removing nitrogen oxides and sulfur oxides that are more stable and fast, It is an object of the present invention to improve the stability and the efficiency of removing nitrogen oxides and sulfur oxides while enhancing stability by using an aqueous solution of sodium chlorite as a liquid oxidizing agent instead of chlorine dioxide having high toxicity.

The method for removing nitrogen oxides and sulfur oxides according to the present invention comprises the steps of: (1) acidifying a liquid sodium hypochlorite as a reaction liquid; (2) atomization step of ultrasonically atomizing the acidified reaction solution; (3) an oxidizing step of mixing the atomized reaction liquid with a sulfur dioxide nitrogen oxide stream to form a mixing gas stream; And (4) an absorption step of contacting the mixed gas stream with water to absorb the oxidized nitrogen oxide.

The acidification step can be carried out by passing the reaction solution through a cation exchange resin.

In the atomization step, the ultrasonic wave may be within a range of 10 kHz to 2.5 MHz.

After the absorption step, it may further comprise a first spraying step of spraying the water or acid solution to the mixing air stream.

After the first spraying step, it may further comprise a second spraying step of spraying the water or base solution.

The apparatus for removing nitrogen oxides according to the present invention may further comprise: an ultrasonic atomizer for atomizing liquid sodium hypochlorite which is acidified as a reaction liquid; A gas phase reaction chamber for mixing an atomized reaction liquid and a sulfur oxides gas stream and for retaining a mixing gas stream; And an absorber positioned above the vapor-phase reaction chamber and absorbing oxidized nitrogen oxides in the gas-phase reaction chamber rising from the vapor-phase reaction chamber.

The nitrogen oxide removal apparatus may further comprise a first feeder for feeding water or an acid solution to the absorber.

The nitrogen oxide removal equipment may further include a neutralizer.

The nitrogen oxide removal equipment may further comprise a second feeder for feeding the water or base solution to the neutralizer.

The nitrogen oxide removal equipment may further comprise a third feeder for supplying the gaseous oxidizing agent.

According to the present invention, it is possible to oxidize nitrogen oxides by using a liquid oxidizing agent which is safer and easier to handle than a gaseous oxidizing agent, and to remove and remove oxidized nitrogen oxides at a rapid and high removal rate Gt; of the < / RTI >

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view schematically showing a configuration of a nitrogen oxide removal device according to one embodiment of the present invention. FIG.
2 is a side sectional view schematically showing a configuration of a nitrogen oxide removal device according to another embodiment of the present invention.
3 is a side sectional view schematically showing a configuration of a nitrogen oxide removal device according to another embodiment of the present invention.

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

The method for removing nitrogen oxides according to the present invention comprises the steps of: (1) acidifying a liquid sodium hypochlorite as a reaction liquid; (2) atomization step of ultrasonically atomizing the acidified reaction solution; (3) an oxidizing step of mixing the atomized reaction liquid with a sulfur dioxide nitrogen oxide stream to form a mixing gas stream; And (4) an absorption step of contacting the mixed gas stream with water to absorb the oxidized nitrogen oxide.

The term "sulfur oxides nitrogen oxide " in the present invention means that sulfur oxides and nitrogen oxides are both or alternatively contained, and it is used for various kinds of factories such as smelters, thermal power plants, sulfuric acid manufacturing plants, bunker- Home, and automobile exhaust.

The acidification step (1) comprises acidifying liquid sodium hypochlorite as a reaction liquid, and by this acidification, chlorine dioxide can be generated from sodium chlorite. Sodium chlorite itself has a pH of 12 or higher and is chemically very stable as long as it is not irradiated with ultraviolet rays. Therefore, it is used to effectively oxidize and absorb nitrogen oxides and sulfur oxides because the reaction rate is slow to oxidize nitrogen oxides There may be a disadvantage that the efficiency is low or the removal speed is low. On the other hand, sodium hypochlorite with a low pH can be used as an oxidizing agent useful for oxidation of nitrogen oxides and sulfur oxides, but sodium acid chlorite is very unstable and can not be stored as it is. Therefore, in the present invention, And it is characterized in that it is acidified just before it is mixed with the nitrogen oxide stream. In addition, since sodium hypochlorite easily dissolves in water, it can be easily removed subsequently. Anhydrous NaClO ₂ is stable and does not decompose even when heated at 350 ° C for 30 minutes, but starts to decompose at 130 to 140 ° C due to the moisture normally contained. The aqueous solution may be considered stable if it is not exposed to light in the case of alkalinity. The concentration of the aqueous sodium chlorite solution may be in the range of 0.2 to 15%, and more preferably 2 to 10%. If the concentration is less than 0.2%, the water content is too high to lower the oxidation rate of nitrogen oxides. If the concentration is more than 15%, the oxidizing power becomes too strong and corrosion problem arises.

The acidification step may be carried out by adding an acidic substance to the reaction solution, but it may preferably be performed by passing the reaction solution through the cation exchange resin in consideration of the design, manufacture, and operation convenience of the apparatus . Cation exchange resin is a synthetic resin that is added to other aqueous solution and plays a role of exchanging cations with cations in aqueous solution and plays a role of exchanging cations in own solution and cations in other aqueous solution. The cation exchange resin is an insoluble polymer acid, and is classified into a strongly acidic cation exchange resin and a weakly acidic cation exchange resin depending on the strength of acidity by the exchanger. As the matrix of the cation exchange resin, a hybrid polymer of styrene and divinylbenzene is usually used. In the weak acid cation exchange resin, a hybrid polymer of methacrylic acid and divinylbenzene is used. As the exchanger, there are sulfone groups as strong acid groups, carboxy groups and phenolic hydroxyl groups as weak acid groups, and sulfone group (-PO ₃ H ₂ ) and arson group (-AsO ₃ H ₂ ). The cation exchange resin may exist in various forms, and may be selected according to the effective pH range. For example, in case of pH 2 or more, R-SO ₃ H type; for pH 4 or higher, R-CH ₂ SO ₃ H type; When the pH is 6 or more, the R-COOH type can be used. As the cation exchange resin, a polystyrenesulfonic acid type resin, which is a strongly acidic cation exchange resin, can be preferably used. The strongly acidic cation exchange resin means a cation exchange resin having strong acidity, and a sulfonic acid type resin having a sulfone group can be used as an exchange agent. As the sulfonic acid type resin, phenol sulfonic acid type resin or polystyrol sulfonic acid type resin can be exemplified. The polystyryl sulfonic acid type resin may be one obtained by copolymerizing styrene and divinylbenzene followed by sulfonation with concentrated sulfuric acid. However, the present invention is not intended to be limited thereto, and any resin that can acidify the reaction solution may be used Possible is to be understood. The cation exchange resin can be regenerated and reused on a regular basis and in a deteriorated function, and the regeneration of the cation exchange resin can usually be carried out by passing an aqueous solution of strong acid or strong acid material.

In the atomization step (2), the acidified reaction liquid is atomized by ultrasonic waves, and the reaction liquid in the liquid phase becomes a droplet (mist) having a very small particle diameter by the atomization through the ultrasonic waves, so that the reaction liquid can float in the air stream. Therefore, in addition to oxidation by the gas phase reaction of nitrogen oxides and sulfur oxides in the sulfurized nitrogen oxide stream by the acidified reaction liquid, that is, acidified sodium chlorite by the chlorine dioxide generated in the acidified sodium chlorite, Oxidation of nitrogen oxides and sulfur oxides in the sulfur dioxide nitrogen oxide stream by sodium chlorate can be performed in parallel by the liquid phase reaction, so that the oxidation of nitrogen oxides and sulfur oxides can be promoted. That is, according to the present invention, it becomes possible to effectively oxidize nitrogen oxides by atomizing the acidified sodium chlorite and mixing with a sulfur oxides nitrogen oxide stream. Particularly, in this process, sodium dodecyl sulfate is more stable in liquid state so as to be present for as long as possible to facilitate handling, while acidification and atomization are performed just before oxidation of nitrogen oxides to promote oxidation of nitrogen oxides and sulfur oxides And to make it possible to remove it effectively and effectively.

In the atomization step, the ultrasonic wave may preferably be within the range of 10 kHz to 2.5 MHz, more preferably within the range of 20 kHz to 2.4 MHz, and most preferably from 1.0 MHz to 2.4 MHz. When the frequency of the ultrasonic wave is less than 10 kHz, the efficiency of atomization deteriorates, so that the nitrogen oxide removal rate is lowered and the removal time is also increased. As a result, the overall removal efficiency of nitrogen oxides and sulfur oxides may be lowered. The decomposition of sodium hypochlorite by strong ultrasonic energy is promoted, so that the efficiency of oxidation of nitrogen oxides and sulfur oxides may deteriorate.

In the oxidation step (3), oxidation is progressed automatically by mixing the atomized reaction liquid with a stream of nitrogen oxides of sulfur oxides to form a mixing air stream. Then, in the absorption step of (4), the mixing air stream is contacted with water The nitrogen oxides are oxidized from the nitrogen oxides stream and absorbed in the water by absorbing the oxidized nitrogen oxides. The nitrogen oxides are absorbed in the water and are liquefied by the waste liquid, that is, the acidic waste liquid, and are removed from the airflow.

According to the present invention, after the absorption step, it may further comprise a first spraying step of spraying the water or acid solution to the mixing air stream. In the first spraying step, an additional acid solution is further sprayed into the mixing stream to enable further conversion of unreacted sodium chlorite to chlorine dioxide, which can further promote oxidation of nitrogen oxides and sulfur oxides, Thereby promoting the absorption of oxidized nitrogen oxides and sulfur oxides. Therefore, even in the case where the content of nitrogen oxide in the sulfur oxides is rapidly increased, it is possible to efficiently oxidize and remove the nitrogen oxides.

According to the present invention, it is possible to further comprise a second spraying step for spraying the water or base solution after the first spraying step, and further spraying the base solution in the second spraying step, whereby the reaction by- Neutralization of nitrogen oxides and sulfur oxides that are not absorbed and removed by water, neutralization of acidic waste liquids that are absorbed and absorbed by water, and alternatively water is supplied to dilute or remove nitrogen oxides and sulfur oxides Can be increased.

The oxidation and absorption of nitrogen oxides and sulfur oxides in the sulfur oxides of nitrogen oxides as described above can be stoichiometrically reacted at an equivalence ratio. In particular, nitrogen monoxide and nitrogen dioxide in the nitrogen oxides are converted into nitrogen oxides And it can be absorbed and removed by water. Especially, it is stored and handled as sodium hypochlorite stable at room temperature, and acidification and atomization are performed immediately before the reaction to promote the oxidation reaction of nitrogen oxides and sulfur oxides to rapidly and effectively remove nitrogen oxides .

1 to 3, the apparatus for removing nitrogen oxides 10 according to the present invention comprises an ultrasonic atomizer 11 for atomizing a liquid sodium hypochlorite which has been acidified as a reaction liquid; A gas phase reaction chamber (12) for mixing an atomized reaction liquid and a sulfur oxide gas stream and for retaining a mixing gas stream; And an absorber (13) located above the vapor phase reaction chamber (12) and absorbing oxidized nitrogen oxides in a gas mixture rising from the vapor phase reaction chamber (12).

The ultrasonic atomizer 11 rapidly applies ultrasonic waves to a liquid reaction solution, that is, an acidified liquid sodium hypochlorite to atomize it, thereby rapidly vaporizing the chlorine dioxide generated by the acidification, and the liquid reaction solution also has a very small particle diameter It is made into a droplet (mist) so that it can float in the air stream. Therefore, in addition to oxidation by the gas phase reaction of nitrogen oxides and sulfur oxides in the sulfurized nitrogen oxide stream by the acidified reaction liquid, that is, acidified sodium chlorite by the chlorine dioxide generated in the acidified sodium chlorite, Oxidation of nitrogen oxides and sulfur oxides in the sulfur dioxide nitrogen oxide stream by sodium chlorate can be performed in parallel by the liquid phase reaction, so that the oxidation of nitrogen oxides and sulfur oxides can be promoted.

A sensor S for measuring the amount of nitrogen oxides and sulfur oxides in the sulfur oxide nitrogen oxide stream introduced into the nitrogen oxide removal apparatus 10 according to the present invention may be installed in front of the ultrasonic atomizer 11 , The sensor (S) measures the inflow of nitrogen oxides and sulfur oxides to induce a stoichiometric oxidation reaction. To this end, the ultrasonic atomizer (11) is connected to a reaction liquid conduit (111) The reaction liquid conduit 111 is connected to a means for acidifying the reaction liquid, preferably a cation exchange resin 112, and further includes a feed pump 113 for pumping and supplying the reaction liquid, The storage tank 114 may be further connected. In particular, the feed pump 113 may be a metering pump (metering pump) capable of increasing and decreasing the amount of the reaction liquid in proportion to the amount of the nitrogen oxide inflow detected by the sensor S.

The gas phase reaction chamber (12) functions to mix the atomized reaction liquid and the sulfur oxide nitrogen oxide stream and to keep the mixing air flow. The gas phase reaction chamber (12) temporarily stores the acidic waste liquid generated upon the removal of the oxidized nitrogen oxides and sulfur oxides by absorption It functions as a storage space. The gas-phase reaction chamber 12 may be omitted when a small amount of a stream of nitrogen oxides is treated, that is, when the amount of gas to be treated is small.

The absorber 13 is positioned above the vapor phase reaction chamber 12 and functions to absorb oxidized nitrogen oxides in the gas mixture rising from the vapor phase reaction chamber 12. The absorber 13 is composed of a packed bed packed with a filler such as a lashing or the like so that the contact area with the mixer flow is increased due to the increase of the specific surface area due to the packing in the packed bed, it is possible to increase the chance of contact and reaction between the sodium hypochlorite in the mixed gas stream and the converted chlorine dioxide in the mixed gas stream and the nitrogen oxide in the stream of the ammonium nitrogen oxide stream to be removed, And functions to help absorb and remove oxidized nitrogen oxides as objects to be removed by a liquid as a by-product. The Raschig ring filled in the absorber 13 may preferably be a Raschig ring having a diameter of 150 mm. Rashihing is a type of artificial filling, which is made of hollow, short cylinder of the same diameter and height, and is made of magnetic, stainless steel, carbon material and synthetic resin.

Therefore, it is preferable that the ultrasonic atomizer 11 is installed in the vicinity of the entrance of the apparatus 10 for removing nitrogen oxides according to the present invention. When the gas phase reaction chamber 12 is present, It is preferable that the vapor phase reaction chamber 12 is located at the rear side and the absorber 13 is positioned above the vapor phase reaction chamber 12. If the gas phase reaction chamber 12 is not present, it may be located behind the ultrasonic atomizer 11, more preferably after the ultrasonic atomizer 11.

The apparatus 10 for removing nitrogen oxides according to the present invention may further include a neutralizer 14. The neutralizer 14 is composed of a packed bed filled with a filler similar to the absorber 13, and neutralizes and absorbs an acidic substance (that is, oxidized nitrogen oxide) in the mixing air stream by spraying a basic aqueous solution such as sodium hydroxide Thereby preventing the acidic substance from being released into the atmosphere as it is. The neutralizer 14 may further include a second feeder 141 for supplying a water or base solution to the neutralizer 14 so as to assist in neutralizing and / or removing acidic substances in the mixing air stream have. The second feeder 141 may be a nozzle for supplying a water or base solution to the neutralizer 14, which may include a feed pump 142 for supplying a water or base solution and a reservoir 143 for storing a water or base solution Can be connected. Lashings that are filled in any other filler layer, including the neutralizer 14, may preferably be LASHILLING with a diameter of 25 mm.

2, the apparatus 10 for removing nitrogen oxides according to the present invention may further include a first feeder 131 for feeding water or an acid solution to the absorber 13, In addition to increasing the solubility of the oxidized nitrogen oxides and sulfur oxides by supplying water and increasing the solubility of nitrogen oxides and sulfur oxides by water in the acid solution by supplying the acid solution to the absorber 13, It may be possible to further convert unreacted sodium chlorite to chlorine dioxide. The first supply unit 131 may be connected to a supply pump 132 for supplying water or an acid solution by pumping and a reservoir 133 for storing water or an acid solution.

As shown in Fig. 3, the nitrogen oxide removal equipment 10 according to the present invention can further include a third feeder 15 for supplying a gaseous oxidizing agent. As the oxidizing agent in the gas phase, ozone, chlorine dioxide, oxygen and the like may be used, but the present invention is not intended to be limited thereto, but chlorine dioxide can be preferably used. This can efficiently oxidize the nitrogen oxide efficiently and sufficiently absorb and remove it in the subsequent absorption / removal process in the case where the nitrogen oxide content in the sulfur oxide nitrogen oxide stream increases sharply.

The third feeder 15 is preferably located on top of the ultrasonic atomizer 11 or between the ultrasonic atomizer 11 and the vapor phase reaction chamber 12 because the gaseous oxidant prior to the absorption process is in the sulfur dioxide nitrogen stream It can be an optimal arrangement that allows sufficient reaction with nitrogen oxides to sufficiently oxidize the nitrogen oxides. The third feeder 15 may be a nozzle, in which a storage tank 151 for storing the gaseous oxidizing agent and a feed pump 152 for supplying the gaseous oxidizing agent may be further connected.

The demister 16 may further be installed on the upper portion of the treatment apparatus 10 according to the present invention, preferably the neutralizer 14, and fine droplets, etc. in the airflow discharged by the demister 16 So that the finally purified air can be discharged to the atmosphere through the exhaust pipe 17. [

Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention.

Example  1 to 3

The nitrogen oxide removal apparatus according to the present invention as shown in FIG. 1 is used. In addition, while the ultrasonic frequency of the ultrasonic atomizer is varied, sodium hypochlorite is supplied as a reaction liquid to remove nitrogen oxide, And the results are shown in Table 1 below.

Comparative Example  One

The procedure was carried out in the same manner as in Example 1 except that an ultrasonic atomizer was not used.

Comparative Example  2

The procedure of Example 1 was repeated except that the ultrasonic atomizer and sodium chlorite were not used but only chlorine dioxide was used.

division Flesh Ultrasonic frequency Removal rate (%) Removal time Example 1 ○ 20 to 48 kHz 95% 13 seconds Example 2 ○ 220 kHz 96% 5 seconds Example 3 ○ 2.3MHz 98% 1.4 seconds Comparative Example 1 X X 92% 90 seconds Comparative Example 2 X X 98% 1.2 seconds

As shown in Table 1, according to the present invention, it has been confirmed that even by using liquid sodium hypochlorite by applying ultrasonic waves, nitrogen oxides can be removed at a sufficiently high rate in a short time . In particular, it can be seen that as the frequency of ultrasonic waves increases, the removal rate of nitrogen oxides and sulfur oxides increases and the removal time can be shortened in proportion to the increase in the frequency of the ultrasonic waves. Therefore, by using sodium hypochlorite as the reaction liquid by the ultrasonic atomizer, It can be confirmed that it can be removed.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

10: nitrogen oxide removal device 11: ultrasonic atomizer
12: gas phase reaction chamber 13: absorber
14: Heavy machine 15: Third feeder
16: Demister 17: Exhaust pipe

Claims (10)

In oxidizing and removing nitrogen oxides by water,
(1) an acidification step of acidifying liquid sodium hypochlorite as a reaction liquid;
(2) an atomization step of atomizing the acidified reaction solution with ultrasonic waves having a frequency within a range of 10 kHz to 2.5 MHz;
(3) an oxidizing step of mixing the atomized reaction liquid with a sulfur dioxide nitrogen oxide stream to form a mixing gas stream; And
(4) an absorption step of contacting the mixing air stream with water to absorb oxidized nitrogen oxide;
And removing the nitrogen oxides. The method according to claim 1,
Wherein the acidification step is carried out by passing the reaction solution through a cation exchange resin. delete The method according to claim 1,
Further comprising a first spraying step of spraying a water or acid solution to the mixing air stream after the absorption step. 5. The method of claim 4,
Further comprising a second spraying step of spraying a water or base solution after the first spraying step. An ultrasonic atomizer for atomizing liquid sodium hypochlorite, which has been acidified as a reaction liquid, with ultrasonic waves having a frequency within a range of 10 kHz to 2.5 MHz;
A gas phase reaction chamber for mixing an atomized reaction liquid and a sulfur oxides gas stream and for retaining a mixing gas stream; And
An absorber positioned above the gas-phase reaction chamber and absorbing oxidized nitrogen oxides in the gas mixture rising from the gas-phase reaction chamber;
Wherein the nitrogen oxide removal device comprises: The method according to claim 6,
Further comprising a first feeder for feeding water or an acid solution to the absorber. The method according to claim 6,
Further comprising a neutralizer. The method according to claim 6,
Further comprising a second feeder for feeding the water or base solution to the neutralizer. The method according to claim 6,
Further comprising a third feeder for feeding the gaseous oxidizing agent.

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