KR20190043942A - Apparatus and method for removing nitrogen oxide and sulfur oxide - Google Patents

Abstract

According to an embodiment of the present invention, a nitrogen oxide and sulfur oxide removing apparatus includes: an electrochemical cell in which a first chlorinated oxidizer and hydroxide ions (OH^-) are generated; an acidity control unit which includes a second chlorinated oxidizer generated as pH is controlled after mixing the hydroxide ions with the chlorinated oxidizer introduced from the electrochemical cell; a contact unit which is in contact with the second chlorinated oxidizer introduced from the outside and introduced from acidity control unit and exhaust gas including nitrogen oxide and sulfur oxide, and includes nitrate ions generated by oxidizing nitrogen oxide and sulfite ions generated by oxidizing sulfur oxide or being dissolved with water; and a collection unit which is connected with the electrochemical cell and collects and removes ammonium salts generated as each of sulfur ions and nitrate ions introduced to the electrochemical cell from the contact unit is combined with the ammonium ion. The present invention is able to reduce installation and operation costs.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an apparatus for removing nitrogen oxides and sulfur oxides,

There is provided a nitrogen oxide and sulfur oxide removal device and a removal method capable of continuously and simultaneously removing nitrogen oxides and sulfur oxides from an exhaust gas through a chlorine-based oxidant produced by an electrochemical method.

Exhaust gases from fossil fuel-based power plants, boilers, incinerators and automobile engines contain large quantities of nitrogen oxides and sulfur oxides. Here, nitrogen oxides cause photochemical smog by irradiation of the sunlight, can stimulate the eyes and nose, can cause pulmonary hyperemia, pulmonary edema, obstructive bronchitis, etc., and bind to blood hemoglobin to form methemoglobin Thereby preventing oxygen transmission in the human body. Sulfuric acid reacts with water in high atmospheric humidity to produce aerosol, which can cause light scattering, corrosion of metals and materials, reduction in visual field, and can cause acute, chronic respiratory disease, asthma .

Currently, the process for removing NOx can be divided into dry denitrification and wet denitrification. Catalytic cracking, selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) catalytic reduction, non-selective catalytic reduction, spinning, and adsorption. The most widely used denitrification technology is a selective catalytic reduction process. The selective catalytic reduction process exhibits high denitrification performance and relatively low secondary pollution. However, it may have a problem that the energy consumption is relatively large.

Wet denitrification techniques include absorption-oxidation, absorption-reduction, oxidation-absorption, and oxidation-absorption-reduction. The wet denitrification technique can be performed by an aqueous solution containing an oxidizing agent such as KMnO ₄ , H ₂ O ₂ , NaClO ₂ , O _3, etc. and a metal chelate. Such wet denitrification technology can perform denitrification and desulfurization at the same time, but the installation cost is relatively higher than that of the dry denitrification technology and the denitrification efficiency may be low.

Currently, processes for removing sulfur oxides can also be classified as dry processes and wet processes. Approximately 90% of large combustion facilities such as power plants are performing sulfuric acid removal by wet limestone process (flue gas desulfurization, FGD) or spray drying process. This sulfuric acid removal process shows a sulfuric acid removal rate of about 90%. However, calcium sulfide collected as a calcium end product is low in utilization, and heavy metals such as mercury used in the process have toxicity, which may cause secondary environmental pollution.

Nitrogen oxides and sulfur oxides are the main cause of air pollution such as causing fine dusts, and it is very harmful to the human body and it is necessary to reduce them. However, the process for effectively removing them simultaneously has not been commercialized. In addition, since the nitrogen oxides and the sulfur oxides are now removed by complicated treatment processes in which the respective substances are separated, the cost and the processing time are increased. Therefore, an efficient and continuous process is required to minimize this. In addition, it is necessary to develop a technology that is highly applicable in the field in consideration of other contaminant composition, space velocity, and exhaust gas flow rate of the exhaust gas generating source.

In the case of the Korean patent (Application No. 10-2005-0034119) concerning the method of removing sulfur dioxide and nitrogen oxide in combustion exhaust gas using chlorine dioxide, chlorine dioxide alone may not be effective as an oxidizing agent, The removal can be smoothly performed, and the operation cost can be increased because separate equipment for adjusting the pH is required.

The apparatus and method for removing nitrogen oxides and sulfur oxides according to an embodiment of the present invention are for simultaneously removing nitrogen oxides and sulfur oxides contained in the exhaust gas.

The apparatus and method for removing nitrogen oxides and sulfur oxides according to an embodiment of the present invention are intended to simplify the process and reduce installation cost and operation cost.

The apparatus and method for removing nitrogen oxides and sulfur oxides according to one embodiment of the present invention are for recycling recovered material.

Embodiments according to the present invention can be used to accomplish other tasks not specifically mentioned other than the above-described tasks.

An apparatus for removing nitrogen oxides and sulfur oxides according to an embodiment of the present invention includes an electrochemical cell in which a first chlorine-based oxidizing agent and a hydroxide ion (OH ^- ) are generated, a chlorine-based oxidizing agent introduced from an electrochemical cell, An acidity control unit comprising a second chlorine-based oxidant produced by adjusting pH, an exhaust gas introduced from outside and containing nitrogen oxide and sulfur oxide, and a second chlorine-based oxidizer introduced from the acidity control unit, A contact portion including nitrate ions generated by oxidation of oxides and sulfuric acid ions generated by oxidizing sulfur oxides or dissolved in water, and a contact portion connected to the electrochemical cell, wherein nitrate ions and sulfate ions And a recovery unit for recovering and removing the ammonium salt, which is formed by combining with the ammonium ion, respectively.

The electrochemical cell includes a first region and a second region facing each other and spaced apart from each other, a first electrode positioned in the first region and a voltage applied thereto, a second electrode positioned in the second region and applied with a voltage, A second ion exchange membrane located between the first ion exchange membrane and the second ion exchange membrane, the first ion exchange membrane being located between the first ion exchange membrane and the first ion exchange membrane, the second ion exchange membrane being located between the first and second regions, An intermediate region, and an electrolyte may be contained throughout the electrochemical cell.

The first chlorine-based oxidizing agent includes Cl ₂ , and the first chlorine-based oxidizing agent is generated by chlorine ions (Cl ^- ) located in the middle region passing through the first ion exchange membrane and oxidized at the first electrode, Can be generated at the contact portion and introduced into the intermediate region.

Chlorine ions can be generated by reducing the second chlorine-based oxidant at the contact portion.

The hydroxide ion may be generated by reducing water contained in the electrolyte at the second electrode, and the hydroxide ion may pass through the second ion exchange membrane to the intermediate region.

A second chlorine based oxidizing agent is Cl _2, HClO, ClO ^- may include one or more of ^-, or ClO _2.

In the acidity control part, when the acidity is adjusted to less than 3, the second chlorine-based oxidizing agent may include Cl ₂ as a main species, and when the acidity is controlled to 3 to 6, the second chlorine- based oxidizing agent contains HClO and Cl ₂ as the main species If the acidity is controlled to 7 to 9, the second chlorinated oxidizing agent may include HClO, OCl ^- and ClO ₂ ^- as the main species, and when the acidity is adjusted to more than 9, the second chlorinated oxidizing agent may include OCl ^- It can be included as a main species.

At the contact, the second chlorine-based oxidizing agent can be contacted with the exhaust gas by means of one of the spray tower, packed tower, cyclone scrubber, venturi scrubber, jet scrubber, monopole, bubble column, perforated plate tower or bubble tower.

The nitrate ion produced at the contact may contain at least one of NO ₂ ^- or NO ₃ ^- and the sulfate ion produced at the contact may be one of SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , or HOSO ₂ ^- Or more.

And an ammonia supply unit connected to the electrochemical cell and supplying ammonia to the first region.

Water contained in the electrolyte is oxidized at the first electrode, and the protons (H ⁺ ) generated by the first electrode are combined with ammonia to generate ammonium ions.

Nitrate ions and sulfate ions introduced into the intermediate region from the contact portion can pass through the first ion exchange membrane and combine with ammonium ions in the first region.

The ammonium salt may comprise at least one of NH ₄ NO ₂ , NH ₄ NO ₃ , (NH ₄ ) ₂ SO ₃ , or (NH ₄ ) ₂ SO ₄ .

The method of removing nitrogen oxides and sulfur oxides according to an embodiment of the present invention includes the steps of generating a first chlorine-based oxidizing agent and hydroxide ions by applying a voltage to an electrochemical cell, mixing the chlorine-based oxidizing agent with a hydroxide ion pH is controlled to adjust the acidity to produce a second chlorine-based oxidizing agent, an exhaust gas containing nitrogen oxide and sulfur oxide is externally introduced and brought into contact with the second chlorine-based oxidizing agent to oxidize the nitrogen oxide to generate nitrate ions, A contact step of oxidizing cargo or dissolving in water to produce sulfate ion, and a step of introducing nitrate ion and sulfate ion generated in the contact step into an electrochemical cell and then combining with ammonium ion to generate and remove ammonium salt .

The electrochemical cell includes a first region and a second region facing each other and spaced apart from each other, a first electrode positioned in the first region and a voltage applied thereto, a second electrode positioned in the second region and applied with a voltage, A second ion exchange membrane located between the first ion exchange membrane and the second ion exchange membrane, the first ion exchange membrane being located between the first ion exchange membrane and the first ion exchange membrane, the second ion exchange membrane being located between the first and second regions, An intermediate region, and an electrolyte may be contained throughout the electrochemical cell.

In the step of producing the first chlorine-based oxidizing agent and the hydroxide ion, the first chlorine-based oxidizing agent contains Cl ₂ , and the first chlorine-based oxidizing agent passes chlorine ions (Cl ^- ) located in the middle region through the first ion- Which is produced by oxidation at the electrode, and at least a part of the chlorine ions can be produced by reducing the second chlorine-based oxidant in the contacting step.

In the step of producing the first chlorine-based oxidizing agent and the hydroxide ion, the hydroxide ion is generated by reducing the water contained in the electrolyte at the second electrode, and the hydroxide ion can be supplied to the intermediate region through the second ion exchange membrane.

A second chlorine based oxidizing agent is Cl _2, HClO, ClO ^- may include one or more of ^-, or ClO _2.

In the pH adjustment step, adjusting the pH to less than 3 to produce a Cl _2, or adjusting the pH to 3 to 6 to generate HClO and Cl _2, or by adjusting the pH to 7 to 9 HClO, OCl ^-, and ClO ₂ ^- create or adjust the pH to 9 exceeds the OCl ^- may generate.

The nitrate ions produced in the contacting step comprise at least one of NO ₂ ^- or NO ₃ ^- , and the sulfate ions generated in the contacting step comprise one of SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , or HOSO ₂ ^- Or more.

In the recovery step, the protons (H ⁺ ) generated by the oxidation of water contained in the electrolyte at the first electrode and the ammonia supplied from the ammonia supply unit are reacted in the first region to generate ammonium ions, and nitric acid Ions and ammonium ions may be reacted in the first region to produce an ammonium salt, and then the ammonium salt may be separated and removed.

The nitrogen oxide and sulfur oxide removing device and the removing method according to an embodiment of the present invention can simultaneously remove the nitrogen oxide and the sulfur oxide contained in the exhaust gas continuously and can simplify the process and reduce the installation cost and operation cost And the recovered material can be recycled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus for removing nitrogen oxides and sulfur oxides according to an embodiment. FIG.
FIG. 2 is a detailed view of an electrochemical cell in the apparatus for removing nitrogen oxides and sulfur oxides of FIG. 1. FIG.
FIG. 3 is a detailed view of the pH controller and the contact portion in the apparatus for removing nitrogen oxides and sulfur oxides of FIG. 1;

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same reference numerals are used for the same or similar components throughout the specification. In the case of publicly known technologies, a detailed description thereof will be omitted.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. It will be understood that when an element such as a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the element directly over another element, On the other hand, when a part is "directly on" another part, it means that there is no other part in the middle. On the contrary, when a portion such as a layer, film, region, plate, or the like is referred to as being "under" another portion, this includes not only the case where the other portion is "directly underneath" On the other hand, when a part is "directly beneath" another part, it means that there is no other part in the middle.

Throughout the specification, when an element is referred to as " comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

2 is a detailed view of an electrochemical cell in the apparatus for removing nitrogen oxides and sulfur oxides of FIG. 1, and FIG. 3 is a cross- FIG. 3 is a view showing in detail the acidity adjusting unit and the contact portion in the nitrogen oxide and sulfur oxide removing apparatus of FIG.

1 to 3, an apparatus 100 for removing nitrogen oxides and sulfur oxides according to an embodiment of the present invention includes an electrochemical cell 110, an acidity adjusting unit 140, a contact unit 160, (180).

The electrochemical cell 110 includes a first region 112 and a second region 124 facing each other and spaced apart from each other, a first electrode 116 positioned in the first region 112 to which a voltage is applied, A second electrode 126 positioned on the first region 124 and a voltage applied thereto, a first ion exchange membrane 118 positioned between the first region 112 and the second region 124 and adjacent to the first region 112, A second ion exchange membrane 122 located between the first region 112 and the second region 124 and adjacent to the second region 124 and a second ion exchange membrane 122 located between the first ion exchange membrane 118 and the second ion exchange membrane 122, (Not shown).

A water (H ₂ O) -based electrolyte is contained in all the areas of the electrochemical cell 110. For example, an electrolyte may be contained in all portions of the first region 112, the first ion exchange membrane 118, the intermediate region 120, the second ion exchange membrane 122, and the second region 124 . However, the electrolyte in each region may contain different materials.

The first region 112 may consist of a first electrode 116 located below the first electrode 116 and a region 114 which is not the first electrode 116 located above the first electrode 116 in the figure. The second region 124 may consist of a second electrode 126 located at the top in the figure and a region 128 which is not the second electrode 126 located at the bottom in the figure.

The first electrode 116 may be, for example, an oxidizing electrode and may be used in the same sense as an anode or an anode in the specification. The second electrode 126 may be, for example, a reducing electrode, and may be used in the same sense as the cathode or cathode in the specification.

The first electrode 116 and the second electrode 126 may be formed of various known electrode materials applicable to an electrolytic device, a water electrolytic device, a fuel cell, or the like. For example, various kinds of conductors may be used as the electrodes, or electrodes including the electrode substrate and the catalyst applied to the electrode substrate may be used. At this time, the conductor may be formed of at least one selected from the group consisting of titanium (Ti), stainless steel, nickel (Ni), a nickel / chromium (Ni / Cr) alloy, platinum, gold, palladium, iridium ), Ruthenium (Ru), mixtures thereof, or oxides thereof. In the case of the electrode including the electrode substrate and the catalyst, a carbon cloth or the like may be used as the electrode substrate, and a catalyst such as platinum (Pt), ruthenium (Ru), osmium (Os), palladium (Pd) Materials selected from the group consisting of iridium (Ir), carbon (C), other transition metals, or mixtures thereof may be used.

The first electrode 116 and the second electrode 126 may be disposed at appropriate positions to apply electrical attraction to various ions contained in the first region 112 and the second region 124. The shape of the first electrode 116 and the second electrode 126 is not particularly limited and may be variously modified.

Although not shown, the first electrode 116 and the second electrode 126 may be connected to a power supply. Any known power supply may be used as long as it can apply a predetermined voltage to the first electrode 116 and the second electrode 126 as a power supply.

When a predetermined voltage is applied to the first electrode 116 and the second electrode 126, the electrochemical cell 110 is driven to generate the first chlorine-based oxidizing agent and hydroxide ions (OH ^- ).

Here, the first chlorine-based oxidizing agent includes Cl ₂ . The first chlorinated oxidizing agent (Cl ₂₎ is a chloride ion which is located in the intermediate region (120) (Cl ^-) is to move to the first ion exchange membrane 118, a first electrode 116 through the first electrode (116 ). ≪ / RTI > At this time, at least a portion of the chlorine ions may be generated in the contact portion 160, which will be described later, and introduced into the intermediate region 120. The chlorine ions introduced into the intermediate region 120 are again oxidized at the first electrode 116 via the first ion exchange membrane 118 and converted into the first chlorine based oxidizing agent.

The hydroxide ion, which is a basic substance, is produced by reducing water (H ₂ O) contained in the electrolyte at the second electrode 126. The generated hydroxide ions pass through the second ion exchange membrane 122 and are supplied to the intermediate region 120.

The first ion exchange membrane 118 and the second ion exchange membrane 122 may be anion exchange membranes selectively transmitting anions, and various kinds of anion exchange membranes used in electrolysis apparatuses, fuel cells, etc. may be used. For example, the first ion exchange membrane 118 and the second ion exchange membrane 122 may be made of AMX, AHA, ACS of Japan Tokuyama Co., AAV, APS-4 of Japan Celemento, FAN-AEM of Germany Puma- But is not limited thereto.

The first ion exchange membrane 118 and the second ion exchange membrane 122 can separate the first electrode 116 and the second electrode 126 and can separate the first electrode 116 and the second electrode 126, The function of preventing the mixing of the chlorine-based oxidizing agent and the hydroxide ions generated in the second electrode 126 can be performed. Also, the first ion exchange membrane 118 and the second ion exchange membrane 122 can prevent the chlorine-based oxidizing agent, which may remain in the electrolyte, from being reduced at the second electrode 126, which is a cathode.

An intermediate region 120 containing an electrolyte is located between the first ion exchange membrane 118 and the second ion exchange membrane 122. The electrolyte in the intermediate region 120 may contain at least about 1.94 mass% of chloride ions for stable production of the first chlorine-based oxidant.

The first chlorine based oxidizing agent generated in the electrochemical cell 110 is supplied to the acidity adjusting unit 140 in the first region 112 through the first moving pipe 132 and the hydroxide ions are supplied through the second moving pipe 134 And is supplied to the acidity adjusting unit 140 in the intermediate region 120.

The acidity regulator 140 includes a second chlorine-based oxidant generated by mixing a first chlorine-based oxidizing agent and a basic hydroxide ion. A second chlorine based oxidizing agent is Cl _2, HClO, ClO ^- may be one or more ^-, or ClO _2.

The conventional nitrogen oxide and sulfur oxide removal apparatus uses a single oxidizer, but the nitrogen oxide and sulfur oxide removal apparatus 100 according to the embodiment can improve the nitrogen oxide and sulfur oxide removal performance by using various chlorine based oxidizers.

In the acidity regulator 140, the first chlorine-based oxidizing agent and hydroxide ions as basic substances can be mixed at a predetermined ratio by a control device (not shown), whereby the pH can be controlled, The kind of the second chlorine-based oxidizing agent may be different.

For example, if the acidity of the acidity regulator 140 is adjusted to less than about 3, the second chlorine-based oxidizer may include Cl ₂ as the main species, and when the acidity is controlled from about 3 to about 6, The oxidizing agent may include HClO and Cl ₂ as the main species, and when the acidity is adjusted to about 7 to about 9, the second chlorine-based oxidizing agent may include HClO, OCl ^- and ClO ₂ ^- as the main species, when adjusted to exceed the second chlorine-based oxidizing agent is OCl ^- may include the main and slave. The inclusion as a main species means that in addition to the main species, a small amount of other chlorinated oxidizing agents may be contained.

The first chlorine-based oxidizing agent and the hydroxide ion may be continuously injected into the acidity adjusting unit 140, or may be injected stepwise.

The second chlorine-based oxidizing agent generated in the acidity adjusting unit 140 is supplied to the contacting unit 160 through the third moving pipe 142 in the acidity adjusting unit 140.

In the contact portion 160, the externally introduced exhaust gas 152 is brought into contact with the second chlorine-based oxidizing agent introduced from the acidity regulating portion 140.

The exhaust gas 152 is exhausted from an exhaust gas exhaust facility 150 using fossil fuels such as various power generation facilities and is supplied to the contact portion 160 through the fourth moving pipe 154. The exhaust gas 152 is nitrogen Oxides and sulfur oxides. The exhaust gas 152 may include, for example, about 15 ppm or more of nitrogen oxides and about 25 ppm or more of sulfur oxides. A small amount of gases such as CO ₂ , HF, HCl, NH ₃ , SiF ₄ , O ₂ , N ₂ , CO and SH ₂ may be present in the exhaust gas 152 in addition to nitrogen oxides or sulfur oxides. And can be discharged to the outside of the removal device 100 as it is through a separate moving pipe (not shown).

The manner in which the exhaust gas 152 and the second chlorine-based oxidizer are brought into contact can be achieved, for example, by using a second chlorine-based oxidizer in a spray tower, a packed tower, a cyclone scrubber, a venturi scrubber spraying or spraying by means of one of a scrubber, a jet scrubber, a plate tower, a bubble tower, a sieve plate tower, or a bubble cap tray tower. Lt; / RTI >

When the exhaust gas 152 and the second chlorine-based oxidizer are in contact with each other, the nitrogen oxide contained in the exhaust gas 152 is oxidized to generate nitrate ions, and the sulfur oxide contained in the exhaust gas 152 is oxidized It can be dissolved in water to generate sulfate ion. At this time, the nitrate ion may include at least one of NO ₂ ^- or NO ₃ ^- , and the sulfate ion may include at least one of SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , or HOSO ₂ ^- .

The reaction that may be caused by the contact between the nitrogen oxide and the second chlorine-based oxidizing agent can be represented by the following Reaction Schemes 1 to 13.

[Reaction Scheme 1]

NO (g) ↔ NO (aq)

[Reaction Scheme 2]

_{NO (aq) + Cl 2 (} aq) + H 2 O ↔ NO 2 (aq) + 2H + + 2Cl -

[Reaction Scheme 3]

3NO ₂ (aq) + HOCl ↔ NO ₂ (aq) + H ⁺ + Cl ^-

[Reaction Scheme 4]

3NO ₂ (aq) + H ₂ O ↔ 2H ⁺ + 2NO ₃ ^- + NO (aq)

[Reaction Scheme 5]

2NO ₂ (aq) + H ₂ O ↔ HNO ₂ + H ⁺ + NO ₃ ^-

[Reaction Scheme 6]

NO ₂ ^- + HOCl ^- > NO ₃ ^- + H ⁺ + Cl ^-

[Reaction Scheme 7]

HNO ₂ ↔ H ⁺ + NO ₂ ^-

[Reaction Scheme 8]

3HNO ₂ ↔ H ⁺ + NO ₃ ^- + 2NO (aq) + H ₂ O

[Reaction Scheme 9]

NO ₂ (aq) ↔ NO ₂ (g)

[Reaction Scheme 10]

_{2NO (g) + Cl 2 (} g) → 2NOCl (g)

[Reaction Scheme 11]

_{NOCl (g) + H 2 O} → H + + Cl - + HNO 2

[Reaction Scheme 12]

NO (aq) + OCl ^- ↔ NO ₂ (aq) + Cl ^-

[Reaction Scheme 13]

NO ₂ ^- + OCl ^{- -} > NO ₃ ^- + Cl ^-

Referring to equations (1) to (13), NO ₂ ^- or NO ₃ ^- can be generated by an oxidation reaction caused by the contact between the nitrogen oxide and the second chlorine-based oxidizer, and NO or NO ₂ may remain.

The reaction that may occur by the contact of the sulfur oxide and the second chlorine-based oxidizing agent can be represented by the following reaction formulas 14 to 19.

[Reaction Scheme 14]

SO ₂ (g) ↔ SO ₂ (aq)

[Reaction Scheme 15]

SO ₂ (aq) + H ₂ O ↔ HOSO ₂ ^-

[Reaction Scheme 16]

HOSO ₂ ^- ↔ SO ₃ ^2-

[Reaction Scheme 17]

HOSO ₂ ^- ↔ H ⁺ + SO ₃ ^-

[Reaction Scheme 18]

SO ₃ ^2- + H ₂ O → SO ₄ ^2- + 2H ⁺

[Reaction Scheme 19]

SO ₃ ^2- + 2OH ^{- -} SO ₄ ^2- + H ₂ O

Referring to Reaction Scheme 14 to 19, HSO by a reaction which is soluble in water or oxidation of the contact of the sulfur oxides and a second chlorine-based oxidizing agent ₃ ^- (bisulfite ^{_{ion), SO 3 2-, HOSO 2}} - ( hydroxyl sulfonyl ion), and SO ₄ ^2- can be generated, in addition to the SO ₂ can be retained. These sulfate ions may be generated by an oxidation reaction with a second chlorine-based oxidizing agent, or they may be generated by dissolving in water.

In the contact 160, the second is the NOx contained in the exhaust gas (152) by a chlorine-based oxidizing agent and the oxidation, the sulfur oxide as the oxidation / dissolution and second chlorine based oxidant is reduced chloride ion (Cl ^-) is created . The chloride ion (Cl ^-) are oxidized at the first electrode passes through the through 5 Lee Dong - kwan 162 may be fed to the middle region 120 of the electrochemical cell 110, the first ion exchange membrane of claim 1 Chlorine It can be regenerated with an oxidizing agent. Therefore, the nitrogen oxide and sulfur oxides removal apparatus 100 according to the embodiment can be continuously driven without a separate oxidant supply, thereby reducing the process operation cost.

Compounds such as NO, NO ₂ , NO ₂ ^- , NO ₃ ^- , SO ₂ , SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , HOSO ₂ ^- and Cl ^- And may be supplied to the middle region 120 of the electrochemical cell 110 through the second electrode 162. The effluent of the contact portion 160 including these various compounds can be used as the electrolyte of the electrochemical cell 110.

Referring to the above reaction schemes, in the materials introduced into the intermediate region 120 at the contact portion 160, NO and NO ₂ can be converted to nitrate ions NO ₂ ^- or NO ₃ ^- through reaction with water , SO ₂ , HSO ₃ ^- and HOSO ₂ ^- can be converted to sulfate ions SO ₃ ^2- or SO ₄ ^2- .

The nitrate ions and sulfate ions introduced into the intermediate region 120 can be removed and moved to the recovery unit 180 in the form of ammonium salt, and the removal mechanism is as follows.

The nitrate ions and the sulfate ions pass through the first ion exchange membrane 118 and move to the first region 112.

The ammonia supply unit 190 connected to the first region 112 of the electrochemical cell 110 via the sixth moving pipe 192 is configured to supply ammonia NH _{3 in a} urea form or the like, . Next, ammonia (NH ₃ ) combines with water (H ₂ O) contained in the electrolyte and the proton (H ⁺ ) generated by oxidation at the first electrode 116 to generate ammonium ions.

The generated ammonium ions pass through the first ion exchange membrane 118 and combine with nitrate ions and sulfate ions that migrate to the first region 112 to form ammonium salts. The ammonium salts are recovered in the recovery section 180 Can be removed. At this time, the ammonium salt may include at least one of NH ₄ NO ₂ , NH ₄ NO ₃ , (NH ₄ ) ₂ SO ₃ , or (NH ₄ ) ₂ SO ₄ .

The recovery unit 180 can recover the ammonium salt through the precipitation method using the solubility of the ammonium salt or recover the ammonium salt by evaporating the solvent. The recovered ammonium salt can be recycled at an appropriate location.

The reactions that may occur in the first region 112 are summarized in the following Reaction Schemes 20 to 23.

[Reaction Scheme 20]

2Cl ^- ? Cl ₂ + 2e ^-

[Reaction Scheme 21]

2H ₂ O - > O ₂ + 4H ⁺ + 4e ^-

[Reaction Scheme 22]

SO ₃ ^2- + H ₂ O → SO ₄ ^2- + 2H ⁺ + 2e ^-

[Reaction Scheme 23]

NO _x ^- + NH ₄ ^{+ -} > NH ₄ NO _x

(x = 2 or 3)

[Reaction Scheme 24]

SO _x ^- + 2 NH ₄ ^{+ -} (NH 4) ₂ SO _x

(x = 3 or 4)

Referring to equations (20) to (24), in the first region 112, chlorine ions can be oxidized to produce a first chlorine-based oxidant, water can be oxidized to produce protons, and this reaction is one of the sulfate ions SO reach the first region (112) ₃ ² is oxidized to SO ₄ ^2- can take place, the nitrate ions and sulfate ions can take place this reaction is converted into ammonium salt form.

On the other hand, the reaction that can occur in the second region 124 is a reaction of generating hydroxide ions, which can be represented by the following reaction formula (24).

[Reaction Scheme 25]

2H ₂ O + 2e ^- ? 2OH ^- + H ₂

For example, a voltage of 1.00 V or more may be applied to the first electrode 116 and the second electrode 126, and the oxidation reaction of the reaction formula 22 and the water reduction reaction of the reaction formula 25 may occur. Also, when a voltage of 2.06 V or more is applied, the water oxidation reaction as shown in Reaction Formula 21 and the water reduction reaction in Reaction Formula 25 can occur. When a voltage higher than 2.19 V is applied, the chlorine ion oxidation reaction as shown in reaction formula 20 and the water reduction reaction as shown in reaction formula 25 can occur.

The first moving pipe 132 to the sixth moving pipe 192 may be made of a material that is not corroded or damaged by the fluid and may be made of a material such as stainless steel, stainless steel, acrylic polymer, Teflon, or nylon Lt; / RTI >

Further, although not shown, the nitrogen oxides and sulfur oxides removal apparatus 100 may further include an apparatus for monitoring a fluid flow rate regulator, electric conductivity, temperature, or the like.

Hereinafter, the detailed description of the elements overlapping with those of the components and processes described above may be omitted.

The method for removing nitrogen oxides and sulfur oxides according to the embodiment includes the steps of generating a first chlorine-based oxidizing agent and hydroxide ions by applying a voltage to the electrochemical cell 110, mixing the first chlorine based oxidizing agent with the hydroxide ion (pH) to control the acidity to produce a second chlorine-based oxidizing agent; introducing an exhaust gas 152 containing nitrogen oxides and sulfur oxides from the outside into contact with the second chlorine-based oxidizing agent to oxidize the nitrogen oxides to generate nitrate ions A nitric acid ion and a sulfate ion generated in the contact step are introduced into the electrochemical cell 110 and then combined with the ammonium ion to form an ammonium salt, And a recovery step of generating and removing.

First, a step of generating a primary chlorine-based oxidizing agent and a hydroxide ion is carried out.

The first chlorine-based oxidizing agent includes Cl ₂ , and the first chlorine based oxidizing agent oxidizes chlorine ions (Cl ^- ) located in the middle region 120 through the first ion-exchange membrane 118 and the first electrode 116 And at least a portion of the chlorine ions may have been produced by reducing the second chlorine-based oxidant in the contacting step.

The hydroxide ion is generated by reducing water (H ₂ O) contained in the electrolyte at the second electrode 126. After the hydroxide ion passes through the second ion exchange membrane 122 and is supplied to the intermediate region 120, And may be injected into the acidity regulator 140.

Then, an acidity control step is performed.

The second chlorine-based oxidizing agent generated in the acidity controlling step may include at least one of Cl ₂ , HClO, ClO ^- , or ClO ₂ ^- , and the main species may vary depending on the acidity.

Next, a contact step and a recovery step are performed.

(H ⁺ ) generated by oxidation of water (H ₂ O) contained in the electrolyte in the first electrode 116 and ammonia supplied from the ammonia supply unit 190 are supplied to the first region 112 And the ammonium salt is produced by reacting the nitrate ion, the sulfate ion and the ammonium ion generated in the contacting step in the first region 112, and then the ammonium salt is precipitated by the difference in solubility or the solvent is evaporated Separately remove by the method.

The nitrogen oxide and sulfur oxide removing device and the removing method according to the embodiments can remove the nitrogen oxide and sulfur oxide contained in the exhaust gas 152 at the same time continuously and simplify the existing separated and complicated removal process Installation and maintenance can be facilitated. Also, it is possible to efficiently remove nitrogen oxides and sulfur oxides by using various chlorine-based oxidizing agents, and the economical efficiency can be greatly improved by continuously reusing chlorine-based oxidizing agents. In addition, the nitrogen oxides and sulfur oxides removal systems are smaller in scale compared to the most commonly used selective catalytic reduction (SCR) and wet limestone processes (FGD) systems, and therefore, small-scale power plants, fossil fuel- And the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

100: nitrogen oxide and sulfur oxide removal device 110: electrochemical cell
112: first region 116: first electrode
118: first ion exchange membrane 120: intermediate region
122: second ion exchange membrane 124: second region
126: second electrode 140:
150: Exhaust gas discharge facility 152: Exhaust gas
160: contact portion 180:
190: Ammonia supply part

Claims (21)

An electrochemical cell in which a first chlorine-based oxidant and a hydroxide ion (OH < ^- & gt ^; ) are generated,
A second chlorine-based oxidant formed by mixing the chlorine-based oxidant introduced from the electrochemical cell with the hydroxide ion and adjusting the pH thereof;
A nitrate ion which is introduced from the outside and is brought into contact with an exhaust gas containing nitrogen oxides and sulfur oxides and the second chlorine based oxidizing agent introduced from the acidity regulating portion, the nitrate ions generated by oxidizing the nitrogen oxides, And a contact portion containing sulfate ions generated by dissolving
A recovery unit connected to the electrochemical cell for recovering ammonium nitrate ions and ammonium sulfate ions generated by combining the nitrate ions and the sulfate ions with ammonium ions,
Wherein the nitrogen oxides and sulfur oxides are removed.
The method of claim 1,
Wherein the electrochemical cell comprises a first region and a second region facing each other and spaced apart from each other, a first electrode positioned in the first region and applied with a voltage, a second electrode positioned in the second region and applied with a voltage, A first ion exchange membrane located between the first region and the second region and adjacent to the first region, a second ion exchange membrane located between the first region and the second region and adjacent to the second region, And an intermediate region located between the exchange membrane and the second ion exchange membrane, wherein an electrolyte is contained in the entire electrochemical cell.
3. The method of claim 2,
Wherein the first chlorine based oxidizing agent comprises Cl ₂ and the first chlorine based oxidizing agent is generated by chlorine ions (Cl ^- ) located in the middle region passing through the first ion exchange membrane and oxidized at the first electrode, Wherein at least a portion of the chlorine ions are generated at the contact portion and introduced into the intermediate region.
4. The method of claim 3,
And the chlorine ions are generated by reducing the second chlorine-based oxidizing agent at the contact portion.
3. The method of claim 2,
Wherein the hydroxide ion is generated by reducing water (H ₂ O) contained in the electrolyte at the second electrode, and the hydroxide ion passes through the second ion exchange membrane to remove nitrogen oxides and sulfur oxides Removal device.
4. The method of claim 3,
The second chlorine based oxidizing agent is Cl _2, HClO, ClO ^-, ClO _2, or ^- a nitrogen oxide and sulfur oxide removal comprises at least one device.
The method of claim 6,
Wherein the second chlorine-based oxidizing agent contains Cl ₂ as a main species when the acidity is controlled to less than 3, and the second chlorine-based oxidizing agent contains HClO and Cl ₂ as the main species when the acidity is controlled to 3 to 6 includes, and pH that the second chlorine-based oxidizing agent when adjusted to 7 to 9 HClO, OCl ^- when including the main and slave, and the pH is adjusted to 9 more than the second chlorine-based oxidizing agent is OCl ^{- -,} and ClO ₂ predominantly the And the nitrogen oxide and sulfur oxide removal device.
The method of claim 1,
In the contact portion, the second chlorine-based oxidizing agent is sprayed from a spray tower, a packed tower, a cyclone scrubber, a venture scrubber, a jet scrubber, a plate tower ), A bubble tower, a sieve plate tower, or a bubble cap tray tower, wherein the exhaust gas is in contact with the exhaust gas.
The method of claim 1,
The nitrate ion generated at the contact portion includes at least one of NO ₂ ^- or NO ₃ ^- , and the sulfate ion generated at the contact portion is one of SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , or HOSO ₂ ^- Wherein the nitrogen oxides and the sulfur oxides are removed.
3. The method of claim 2,
And an ammonia supply unit connected to the electrochemical cell and supplying ammonia to the first region.
11. The method of claim 10,
Wherein the protons (H ⁺ ) generated by oxidation of water (H ₂ O) contained in the electrolyte are oxidized at the first electrode and the ammonia are combined to generate the ammonium ion.
12. The method of claim 11,
Wherein the nitrate ions and the sulfate ions introduced into the intermediate region from the contact portion pass through the first ion exchange membrane to bond with the ammonium ion in the first region.
The method of claim 1,
Wherein the ammonium salt comprises at least one of NH ₄ NO ₂ , NH ₄ NO ₃ , (NH ₄ ) ₂ SO ₃ , or (NH ₄ ) ₂ SO ₄ .
Generating a first chlorine-based oxidizing agent and a hydroxide ion (OH < ^- & gt ^; ) by applying a voltage to an electrochemical cell,
A pH adjusting step of adjusting pH by mixing the first chlorine-based oxidizing agent and the hydroxide ion to produce a second chlorine-based oxidizing agent,
An exhaust gas containing nitrogen oxides and sulfur oxides is introduced from the outside and brought into contact with the second chlorine based oxidizing agent to oxidize the nitrogen oxides to generate nitrate ions and oxidize or dissolve the sulfur oxides to generate sulfate ions Contact step, and
A step of introducing the nitrate ion and the sulfate ion generated in the contacting step into the electrochemical cell and then combining with the ammonium ion to generate and remove an ammonium salt
≪ / RTI >
The method of claim 14,
Wherein the electrochemical cell comprises a first region and a second region facing each other and spaced apart from each other, a first electrode positioned in the first region and applied with a voltage, a second electrode positioned in the second region and applied with a voltage, A first ion exchange membrane located between the first region and the second region and adjacent to the first region, a second ion exchange membrane located between the first region and the second region and adjacent to the second region, And an intermediate region located between the exchange membrane and the second ion exchange membrane, wherein an electrolyte is included in the entire electrochemical cell.
16. The method of claim 15,
In the step of producing the first chlorine-based oxidizing agent and the hydroxide ion,
Wherein the first chlorine based oxidizing agent comprises Cl ₂ and the first chlorine based oxidizing agent is generated by chlorine ions (Cl ^- ) located in the middle region passing through the first ion exchange membrane and oxidized at the first electrode, Wherein at least a portion of the chlorine ions are generated by reducing the second chlorine-based oxidizing agent in the contacting step.
16. The method of claim 15,
In the step of producing the first chlorine-based oxidizing agent and the hydroxide ion,
Wherein the hydroxide ion is generated by reducing water (H ₂ O) contained in the electrolyte at the second electrode, and the hydroxide ion passes through the second ion exchange membrane and is supplied to the intermediate region, Removal method.
17. The method of claim 16,
Wherein the second chlorine-based oxidant comprises at least one of Cl ₂ , HClO, ClO ^- , or ClO ₂ ^- .
The method of claim 18,
In the step of adjusting the acidity,
Adjusting the pH to less than 3 to produce a Cl _2, or adjusting the pH to 3 to 6 to generate HClO and Cl _2, or adjusting the pH to 7 to 9 by HClO, OCl ^-, and ClO ₂ ^- generate, or pH the adjusted to 9 to greater than OCl ^- a generation method for removing nitrogen oxides and sulfur oxides to.
The method of claim 14,
The nitrate ion produced in the contacting step comprises at least one of NO ₂ ^- or NO ₃ ^- , and the sulfate ion generated in the contacting step is SO ₃ ^2- , SO ₄ ^2- , HSO ₃ ^- , or HOSO ₂ ^- ≪ / RTI > wherein at least one of the nitrogen oxides and sulfur oxides is removed.
The method of claim 14,
In the recovering step,
(H ⁺ ) generated by oxidation of water (H ₂ O) contained in the electrolyte in the first electrode and ammonia supplied from the ammonia supply unit react in the first region to generate the ammonium ion,
Wherein the nitrate ion and the ammonium ion generated in the contacting step are reacted in the first region to produce the ammonium salt, and then the ammonium salt is separated and removed.

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