KR20020094582A - Eliminator Removing Nitrogen Oxides In Flue Gases And Method For Removing Nitrogen Oxides Thereby - Google Patents

Abstract

PURPOSE: A NOx scavenger for removal of nitrogen oxides from exhaust gas and method for removing NOx using the same are provided, which can remove acidic gas such as hydrogen chloride, sulfur oxides, carbon monooxide and dioxin as well as nitrogen oxide. CONSTITUTION: With the removing agent containing more than 0.02 wt.% of oxidizing agent, 1 to 40 wt.% of metal halogen compound compared to the oxidizing agent, diluting agent of water, inorganic powder or mixture of water and inorganic powder in the form of solution, powder or slurry, and alkali or buffer, the removing method comprises the following steps of absorbing the nitrogen oxide as a stable state from the exhaust gas by spraying the liquid removing agent to the scrubber to oxidize the nitrogen oxide contained the exhaust gas; recovering the liquid removing agent from the scrubber with the purified gas being emitted.

Description

Eliminator Removing Nitrogen Oxides In Flue Gases And Method For Removing Nitrogen Oxides Thereby

The present invention relates to a remover for removing nitrogen oxide contained in exhaust gas and a method for removing nitrogen oxide thereby. More specifically, the present invention provides a removal agent for removing aromatic halides including acidic gases such as nitrogen oxides, hydrogen chloride and sulfur oxides, carbon monoxide and dioxins contained in exhaust gases emitted from various combustion facilities such as boilers, power plants, incinerators, and the like. This removal agent is used to provide a method for removing these harmful gases contained in the exhaust gas. The remover of the present invention can remove not only nitrogen oxides but also other harmful gases from the exhaust gas at the same time, and can also remove harmful gases such as nitrogen oxides from the exhaust gas by a simple method using the remover of the present invention.

Selective catalytic reduction (SCR) is the most representative technique for removing nitrogen oxides from exhaust gas. The selective catalytic reduction method generally makes the catalyst prepared by reacting precious metal materials such as platinum, palladium, rhodium, or other transition metal materials such as vanadium, iron, cobalt, copper, etc. with titanium dioxide, vanadium oxide, alumina, zeolite, etc. Combined with a substrate such as a strong honeycomb type Cordierrite and loaded into the reaction column in multiple stages or granulated to fill the reaction column, and then ammonia or ammonia water is used as a reducing agent to the catalyst heated to high temperature. By spraying, only nitrogen oxide is selectively reduced to change to nitrogen gas. However, this SCR method has the following problems. That is, a large amount of investment is required because a catalyst tower must be installed, and the reaction gas requires a facility for heating the exhaust gas separately because the temperature of the exhaust gas is 200 ° C.-300 ° C. or higher. In addition, additional storage and injection equipment for ammonia (water) is required, as well as a separate complement to remove excess or unreacted ammonia gas. In addition, when the particulate catalyst is packed and used, the pressure loss of the exhaust gas is very large, and when the honeycomb catalyst is laminated, the honeycomb structure is destroyed by dust and the like and the life of the catalyst is reduced.

On the other hand, the selective non-catalytic reduction method (SNCR) is to inject ammonia or ammonia or urea solution directly to the combustion site to reduce the nitrogen oxide, there are the following problems. In other words, it is difficult to inject ammonia completely and mix it with the hot exhaust gas, and it is difficult to control the temperature properly. (If the temperature is too low, unreacted ammonia is discharged. If the temperature is too high, NH ₃ becomes NO. Oxidized). In addition, there is a limit to the removal rate of nitrogen oxides (typically 60% is the limit line).

Meanwhile, as a prior art for removing nitrogen oxides using an oxidant, Korean Patent Application No. 1998-0027843 proposes a three-step process, as schematically shown in FIG. 1. That is, NOCl is oxidized to NO ₂ by injecting NaClO ₂ as an oxidizing agent to the first reaction tower (first water tower), and the NO ₂ gas introduced from the first reaction tower is converted into a second reaction tower (second). Na ₂ S, which is a reducing agent, was sprayed in the spraying tower to reduce NO ₂ to N ₂ (reduction step), and NaOH was added to neutralize the gas in which the redox reaction was terminated in the third reaction tower (third spraying tower). (Neutralization stage).

However, this method has a complicated process configuration compared to the conventional wet alkali scrubbing method using a single reaction column, and in order to effectively remove NO gas, the concentration of NaClO _{2, which} is an oxidizing agent, needs to be high. In addition, the process of adding sulfuric acid to NaClO ₂ as an oxidant in the first reaction column has a problem of lowering the pH of the solution, thereby lowering the ability to neutralize the acid gas contained in the exhaust gas. In addition, the process of increasing the oxidation efficiency by installing an oxidation catalyst in front of the first reaction tower to increase the NO removal efficiency by the oxidant not only requires additional energy cost to raise the exhaust gas but also lowers the economic efficiency due to the expensive catalyst cost. there is a problem.

The other technique using an oxidant (Patent application 1995-702056) also uses a combination of a reduction process and a neutralization process together with an oxidation process using an oxidant to simultaneously remove nitrogen oxides and sulfur oxides. As in 1998-0027843), there is a problem in that the cost of the drug is increased due to the economical efficiency due to the configuration of a complex process, the efficiency decrease when the concentration of the oxidant is low.

On the other hand, in the case of the aromatic halogen compound removal technology including dioxin, a technology for decomposing using a high-pressure discharge facility, a plasma, an oxidation catalyst tower, etc. has been developed, but all have high installation cost, maintenance cost, operation technology, and efficiency. In the case of using activated carbon to add a lot of adsorption.

Accordingly, it is an object of the present invention to remove nitrogen oxides as well as other acid gases, such as hydrogen chloride and sulfur oxides, carbon monoxide and dioxins, in a simple and convenient single process of spraying liquid (aqueous solutions), powders or slurries, and now It is to provide a method for removing harmful gases such as nitrogen oxides contained in the exhaust gas using a geoagent.

In addition, the object of the present invention is to simplify the process compared to the process of removing nitrogen oxides contained in the exhaust gas by using an existing oxidant, but the oxidation efficiency is improved, reducing the amount of expensive oxidants and reducing costs, It is to provide a product (nitrogen oxide remover in exhaust gas) with excellent oxidation and absorption ability of nitrogen oxides in all pH ranges. These removers are not very constrained by the applied pH and therefore have very high flexibility for the application.

It is also an object of the present invention to provide a remover capable of effectively removing nitrogen oxides from exhaust gas without incurring expensive catalyst towers or exhaust gas heating costs (energy costs) and a removal method using the same.

In addition, an object of the present invention is to provide an excellent application technology that does not require additional processes because the existing wet, (semi) dry alkali absorption tower, bag filter, electrostatic precipitator, cyclone or the like process is used as it is.

It is also an object of the present invention to provide a remover for removing nitrogen oxides in the exhaust gas applicable in a wide temperature range from room temperature to a high temperature of 500 ℃.

Other objects and advantages of the invention will be fully understood from the description and the specific examples thereof.

1 shows a schematic diagram of a process for treating nitrogen oxides in exhaust gases according to the prior art.

2 shows a conceptual diagram of a process for applying a remover in the form of a liquid or low concentration slurry according to the present invention.

3 shows a conceptual diagram of a process for applying a remover in powder or slurry form according to the invention.

4 shows a conceptual diagram of an apparatus for evaluating the performance of the remover in liquid, slurry and powder form of the present invention.

The present invention provides an aromatic halide including nitrogen oxides, sulfur oxides, and acid gases such as hydrogen chloride, carbon monoxide and dioxins contained in the exhaust gas, in particular, a removal agent capable of removing nitrogen oxides. The remover of the present invention includes an oxidizing agent and a metalhalogen compound. If the remover of the present invention can be injected to remove nitrogen oxides from the exhaust gas according to the state of the remover, it may have only an oxidizing agent and a metal halogen compound, but usually further includes a diluent, and the diluent is water, inorganic powder or water. And a mixture of inorganic powders. Thus, the remover of the present invention has the form of an aqueous solution, powder or slurry.

In the remover of the present invention, the amount of the oxidant is at least 0.02% by weight, and the amount of the metalhalogen compound may range from 0.5 to 40% by weight of the oxidant.

In addition, the scavenger of the present invention may further include an acid or base, particularly a base, or a buffer to mitigate the change in pH for the adjustment of pH. Usually pH is adjusted in the range of 2-14, Preferably it is 4-14.

In addition, the present invention provides a method for removing harmful gases such as nitrogen oxides from the exhaust gas by using the above remover. In the removal method of the present invention, when the removal agent is a liquid (aqueous solution), introducing an exhaust gas containing nitrogen oxide or the like into a wet scrubber, and the liquid removal agent as described above is introduced into the exhaust gas introduced from the wet scrubber. The step of oxidizing nitrogen oxides contained in the exhaust gas by spraying to absorb nitrogen oxides in a stable form into the liquid remover, and exhausting the exhaust gas from which nitrogen oxides are removed, and absorbing the nitrogen oxides. Recovering from the wet scrubber. In addition, the liquid scrubbing agent absorbing nitrogen oxides contained in the exhaust gas in a wet scrubber may be treated with a reducing agent to reduce nitrogen oxide (NO _x ) gas to nitrogen (N ₂ ).

In addition, the method for removing nitrogen oxides and the like from the exhaust gas of the present invention is a (semi) dry reactor, bag filter, dry or wet electrostatic precipitator when the exhaust gas containing nitrogen oxide when the remover is in the form of powder or slurry. Or through a cyclone, powder or slurry remover, or inorganic powder and liquid remover simultaneously through different nozzles (semi) dry reactor, (semi) dry reactor shear, bag filter shear, dry Or oxidizing nitrogen oxides in the exhaust gas by injecting them at the front end of the wet electrostatic precipitator or the cyclone to absorb or adsorb nitrogen oxides in a stable form to the remover, and exhaust gas from which nitrogen oxides are removed. In addition to the discharge, and recovering the adsorbent that absorbed or adsorbed nitrogen oxides and the like.

Hereinafter, the present invention will be described in more detail.

In order to achieve the object of the present invention, the present inventors use high efficiency and low cost by using a minimal process that is commonly installed in the existing exhaust gas treatment facility, without using a catalyst tower requiring a separate expensive facility and operation cost. While exploring ways to reduce nitrogen oxides in exhaust gases at a cost, almost all combustion plant exhaust gases have been used for the removal of fine particles and alkali absorption systems such as wet, semi-dry or dry reactors for the removal of sulfur oxides. In view of the fact that there is a dust collection system, a simple method of spraying the exhaust gas stream is used to remove acidic gases such as nitrogen oxides, hydrogen chloride and sulfur oxides and carbon monoxide, and to remove aromatic halogen compounds and the like. A method for removing noxious gases such as nitrogen oxides has been developed.

The present invention prepares scavengers (absorption stabilizers), such as nitrogen oxides, including oxidizing agents and metal halide compounds in various forms, i.e., liquid, slurry and powder forms and simply applies them in a single process to provide nitrogen oxides, sulfur oxides and It is to remove acidic gases such as hydrogen chloride, carbon monoxide and aromatic halogen compounds of dioxins simultaneously.

In the present invention, first, an oxidizing agent and a metal halogen compound (MX) are mixed with water to prepare a liquid mixture. At this time, the oxidizing agent is preferably at least 0.02% by weight, and the metal halide compound is mixed at least 0.0002% by weight. However, the upper limit of the addition amount of the oxidizing agent and the metal halide compound is not particularly limited as long as the remover of the present invention can be injected to remove harmful gas in the exhaust gas, but the oxidizing agent is usually in the range of 0.02-40% by weight. The amount of the metal halide compound may be added in an amount ranging from 1 to 40% by weight relative to the oxidizing agent.

As the oxidizing agent added to the remover of the present invention, chloric acid or salt thereof, hypochloric acid or salt thereof, hypochlorous acid or salt thereof, or other strong oxidizing agent can be used. For example, NaClO, NaClO ₂ , NaClO ₃ , KBrO. ₃ , KClO ₃ , Ca (ClO) ₂ , KMnO ₄ , and the like, and one or two or more of these oxidants may be used together.

In the metal halide compound (MX) added to the remover of the present invention, M includes alkali metal, alkaline earth metal and transition metal. For example, Li, Na, K, Be, Mg, Ca, Ba, Sr, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and the like can be mentioned. And X is a halogen element, and includes F, Cl, Br, and I. These metal halogen compounds can be used together 1 type (s) or 2 or more types.

Such liquid mixture may be used by itself, and in some cases, may be diluted and used within a range satisfying the above composition ratio. In addition, a base or buffer solution may be further added to the liquid mixture, if necessary according to the application process. As such a base or a buffer solution, those commonly used may be used, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, sodium bicarbonate, boric acid and its salts, formic acid and its salts, phthalic acid and its Salts, lactic acid and its salts, malic acid and its salts, tartaric acid and its salts, glycolic acid and its salts, succinic acid and its salts, oxalic acid and its salts, phosphoric acid and its salts, acetic acid and its salts, citric acid and its salts, and the like. have. These bases or buffers may be used together with one kind or two or more kinds as necessary.

Next, the remover of the present invention may be prepared in powder form. In order to prepare the remover of the present invention in powder form, the inorganic powder is added to the water-soluble liquid mixture containing the remover prepared in the form of a liquid mixture, that is, an oxidizing agent and a metal halide compound and, if necessary, a base or a buffer solution. The above ingredients are uniformly supported on the inorganic powder. Thereafter, evaporative drying, reduced pressure drying or vacuum drying is carried out at a temperature of 200 ° C. or lower, preferably 20 to 180 ° C., to obtain a powder form remover.

Thus, water is used as solvent in the remover of the present invention in the form of a liquid mixture, while inorganic powder is used as the carrier in the remover of the present invention in powder form. Such a solvent and a carrier may serve as a diluent in terms of diluting the concentration of the target component in addition to dissolving or supporting the target component. Therefore, in the present invention, the term diluent is used to encompass the solvent (water) and inorganic powder carrier used in the present invention.

Inorganic powders that can be used in the present invention are, for example, CaCO ₃ , CaO, Ca (OH) ₂ , CaCl ₂ , natural or artificial bentonite, activated alumina, activated silica, fly ash, slag, titanium dioxide, clay, volcanic ash, natural Or artificial zeolite, activated carbon, perlite, or turbulent powder, and these inorganic powders may be used together with one kind or two or more kinds.

In addition, the remover of the present invention may be prepared in the form of a slurry. Slurries in the form of slurries can be prepared by dispersing an appropriate amount of inorganic powder in the form of scavenger. In the slurry form remover of the present invention, the solid content is preferably in the range of 0.5 to 50% by weight. In addition, the above slurry products may be precipitated during storage or transport to harden or bind to each other to reduce the dispersibility when used, this problem is to improve the dispersibility of the slurry by adding a polymer dispersant suitable for the characteristics of the powder Can be.

Although the oxidizing agent solution composed of only the oxidizing agent and the base or the buffer solution specified in the present invention shows some degree of activity to remove nitrogen oxides in the acidic region and the high concentration region near pH 4, the activity and duration of activity are increased when the metal halide compound is added. It is greatly increased. The remover of the present invention comprising an oxidant and a metalhalogen compound exhibits good NO _x removal efficiencies that do not appear, especially when the oxidant alone is used, even at low concentrations of less than 0.1% by weight. This is considered to be due to the above-mentioned metal halide compound acting as a catalyst to increase the oxidation capacity.

The use of a base or a buffer solution in the remover of the present invention is such that as the reaction solution moves rapidly to a low pH region by an exhaust gas containing an acid gas such as hydrogen chloride or SO _x , acid gas absorption and removal ability decrease rapidly and the oxidant rapidly increases. It prevents the oxidant consumption from being accelerated as it is decomposed.

The present invention has many differences in the process from the method of removing nitrogen oxides and acid gases in the exhaust gas using known oxidants (Korean Patent Application No. 1998-0027843).

The existing process first converts NO into NO ₂ using an oxidant solution in the first oxidation process, then sends it to the secondary reduction process in gaseous state to reduce NO ₂ to N ₂ using a reducing agent solution, and remains in the exhaust gas. The acidic gas present is using a complex process of absorbing with alkali in the tertiary neutralization process. On the contrary, the present invention converts NO into NO ₂ in a single process using an oxidizer and an absorbent having an increased ability to absorb, and then adsorbs and stabilizes the liquid or powdered remover, and at the same time, acidic gas is applied to the liquid or powdered remover. Adsorption and stabilization.

In other words, in the existing process, the oxidant solution oxidizes NO to NO ₂ , but the oxidant solution has a poor ability to dissolve NO ₂ gas, so most of the NO ₂ is mixed back into the exhaust gas rather than absorbed into the solution and stabilized. I have a problem. Thus, a secondary reduction process is additionally needed. In addition, in the high pH region, since the oxidation capacity is lowered, a neutralization process using strong alkali is added to the end of the reduction process to remove acid gas. Accordingly, the inventors have recognized the limitations of this prior art and have the ability to oxidize NO and absorb NO ₂ and other acid gases in order to efficiently remove nitrogen oxides and acid gases contained in exhaust gases in a single process. Or a material or composition having a good ability to dissolve) and stabilize, preferably a material or composition that can be exerted over a wide pH range. As a result, the oxidizing ability of the oxidizing agent is maximized by mixing the metal halide compound with the oxidizing agent used in the conventional manner to prepare a remover in liquid form, powder form or slurry form, and exhaust gas in almost all pH regions including the acidic and alkaline regions. The removal agent of this invention which can exhibit high reactivity with nitrogen oxide in etc. was obtained.

The remover of the present invention likewise exhibits excellent reactivity not only for liquid products but also for powder or slurry products. In the case of treating the exhaust gas by spraying powder or slurry, a strong oxidizing capacity is necessary to exhibit high reactivity enough to process the exhaust gas sufficiently for a short reaction time of about 10 seconds. Have the ability. Thus, the remover of the present invention can exhibit excellent reactivity even in powder or slurry form.

In the case of using the powder or slurry form remover of the present invention, if the type is selected in consideration of the acid site of the powder surface according to the characteristics of the exhaust gas it will be able to obtain more effective efficiency. In addition, when a non-polar material having a large surface area and a large pore, such as activated carbon, is mixed, it is possible to effectively remove not only acidic gases such as nitrogen oxides, hydrogen chloride and sulfur oxides, but also carbon monoxide and dioxins.

Next, a method for removing acid gases such as nitrogen oxides, sulfur oxides, hydrogen chloride, carbon monoxide and dioxins contained in the exhaust gas by applying the remover of the present invention will be described with reference to the drawings.

Figure 2 shows a conceptual diagram of a process for applying a remover in the form of a liquid or low concentration slurry according to the present invention, Figure 3 shows a conceptual diagram of a process for applying a remover in the form of a powder or slurry according to the present invention.

The present invention is not provided with an expensive catalyst tower, but in the present invention in front of the wet, (semi) dry alkali absorption tower and the dust collector for treating the acid gas and the fine particles that are mostly installed in the exhaust gas treatment process of the combustion facility. The prepared liquid, slurry, or powder product may be sprayed to simultaneously remove nitrogen oxides, acid gases such as SO _x and HCl, carbon monoxide and dioxins in the exhaust gas.

First, referring to Figure 2, the process of applying the remover in the form of a liquid or low concentration slurry according to the present invention. In general, existing exhaust gas purification facilities have a wet alkali absorption tower to absorb and remove acid gases such as sulfur oxides. The removal agent in the form of a liquid or low concentration slurry of the present invention is injected into such a wet alkali absorption tower (wet scrubber) to oxidize nitrogen oxides (NO form) in the exhaust gas introduced into the wet scrubber to NO ₂ , and Absorbs NO ₂ in a stable form. At this time, the remover of the present invention can simultaneously dissolve other acid gases such as sulfur oxides and hydrogen chloride in a stable form. In addition, the carbon monoxide may be oxidized to carbon dioxide and then discharged in a stable form. The wet scrubber to which the remover of the present invention is applied may be operated in a batch manner or continuously. In the case of batch operation, the remover of the present invention is circulated for a predetermined number of times and then disposed of as waste liquid. In the case of continuous operation, the liquid phase remover of the present invention is sprayed and collected at the bottom of the scrubber, which is circulated using a circulation pump and sprayed at the top of the scrubber. At this time, as it continuously circulates, changes in pH, loss due to evaporation of water, and concentration of acid gases such as nitrogen oxides occur. First, in order to respond to a change in pH, a pH meter is installed so that the measured pH is injected with the liquid remover at the lower limit set by the controller, and stops the addition of the liquid remover at the upper limit so that the pH is maintained between the set values. To compensate for the loss due to evaporation of water, add the amount of make-up water as much as the evaporation amount by linking the loss amount with the level switch. In addition, in order to cope with the concentration of acid gases such as nitrogen oxides, an overflow pipe is provided to discharge a certain amount of the liquid remover from the circulation as a waste liquid.

When the pH range is adjusted in the range of pH 2 to 14, preferably in the range of pH 4 to 14, in which the reactivity of the scavenger appears, it is excellent in acidic gases such as nitrogen oxides, hydrogen chloride and sulfur oxides, carbon monoxide and dioxins. Removal efficiency can be obtained.

After the exhaust gas purification treatment, the waste liquid may be added with a water treatment step of reducing the NO _x gas dissolved in the liquid to N ₂ as needed. The waste liquid discharged through the overflow from the wet scrubber circulating water may be treated with a reducing agent. The reducing agent is specifically an alkali metal sulfide, alkaline earth metal sulfide, NaHSO ₃ , Na ₂ SO ₃ , Na ₂ SO ₄ , Na ₂ S ₂ O ₃ , Na ₂ S, K ₂ S, K ₂ SO ₃ , K ₂ S ₂ O ₃ , Na ₂ C ₂ O ₄ , H ₂ C ₂ O ₄ , and the like.

Meanwhile, the remover of the present invention in powder or slurry form may be sprayed onto (semi) dry reaction tower or at its front end as shown in FIG. 3. In this case, the remover and the exhaust gas flow along the turbulence formed in the (semi) dry reaction tower, and come into contact with acid gases such as nitrogen oxides, hydrogen chloride and sulfur oxides and dioxins to oxidize and absorb or adsorb these harmful substances. Remove

If there is no (semi) dry reactor, spraying from the front of a bag filter, cyclone, wet or dry electrostatic precipitator can remove acid gases, such as nitrogen oxides, hydrogen chloride and sulfur oxides, carbon monoxide and dioxins, as in the above reactors. . However, since the contact time between the exhaust gas and the slurry and powder products is small, it is very important to control the shape or length of the pipe or to spray the mixture well with the exhaust gas in order to increase the contact time.

Alternatively, instead of spraying the slurry form of remover, the liquid remover may be sprayed separately from the inorganic powder. Since the slurry-type remover is a mixture of the inorganic powder with the liquid remover, even if separately sprayed at the time of spraying without mixing beforehand can be mixed by the injection can have a similar effect.

The temperature of the above vibration suppression equipment, that is, wet, (semi) dry reactor and bag filter, dry or wet dust collector, cyclone shear is characterized in that the operation at a temperature of 300 ~ 500 ℃ or less, in the case of wet The temperature of is usually less than 90 ℃, in the case of dry, the exhaust gas discharge temperature is usually operating in the range of 120 to 250, and in the case of an electrostatic precipitator may be operated at a high temperature of about 400 to 500 ℃. The remover of the present invention can be applied in all of these various temperature ranges, but more preferably it is used in the range of 50 to 400 ° C. In addition, the remover of the present invention, as mentioned above, can also be harmless by oxidizing carbon monoxide to carbon dioxide.

Hereinafter, specific examples of the present invention will be presented through examples. However, the following examples are only intended to show specific examples of the present invention, it should not be understood that the scope of the present invention is limited to the embodiments.

FIG. 4 shows a conceptual diagram of an apparatus for evaluating the performance of the liquid, slurry and powder form of the present invention. In the following examples, the performance of the present invention was evaluated using these devices.

Example 1

20 ml of NaClO 20%, LiBr 3%, NiI ₂ 1%, NaOH 1% were prepared and placed in the liquid phase reactor of FIG. 4, and the nitrogen and sulfur oxides were maintained while maintaining a constant temperature of 70 ℃. The removal ability of nitrogen oxide and sulfur oxide was measured by passing through the exhaust gas. The exhaust gas composition described above was helium gas containing 1000 ppm of NO, 600 ppm of SO ₂ , 4% of O ₂ , and 7% of H ₂ O, and the mixed gas was passed through the reaction solution at a flow rate of 100 cc / min. In order to measure the removal ability of the nitrogen oxides, the NO concentration of the gas passing through the reaction solution was measured using a chemiluminescence type NO _x analyzer, and then the removal capacity was calculated by the following equation.

NOx removal rate (%) = (inlet NO concentration-outlet NO concentration) / (inlet NO concentration) X 100 (%)

In order to measure the ability to remove sulfur oxides, 200 μl of gas that passed through the reaction solution was collected, and the concentration of sulfur oxides was measured using a gas chromatograph system equipped with a flame photon detector. Was calculated.

Sulfur oxide removal rate (%) = (inlet SO ₂ concentration-outlet SO ₂ concentration) / (inlet SO ₂ concentration) X 100 (%)

The measurement results are shown in Table 1.

Example 2

20 ml of a reaction solution containing 0.2% KClO ₃ , 0.1% KClO, 0.005% MgF ₂ , 0.2 g of acetic acid and 0.2 g of sodium acetate were prepared, and the results were tested in the same manner as in Example 1. It was a sign on 1.

Example 3

20 ml of a reaction solution containing Ca (ClO) ₂ 5%, BaI ₂ 0.5%, VF 0.1%, 0.5 g citric acid and 2 g potassium citrate was prepared, and the results were tested in the same manner as in Example 1 Is shown in Table 1. In addition, as a result of measuring how long the time to remove more than 80% nitrogen oxides, it was confirmed that the time to remove more than 80% nitrogen oxides for 45 minutes.

Example 4

20 ml of a reaction solution having a composition of 5% KMnO _4, 5% NaClO ₂ , 3.5% NaI, and 0.4% NaOH were prepared, and the results were tested in the same manner as in Example 1, and the results are shown in Table 1.

Example 5

20 ml of a reaction mixture of KBrO ₃ 1%, KClO 0.1%, KBr 0.02%, CuF ₂ 0.01%, NaOH 0.04%, H ₃ PO ₄ 0.01% was prepared, and the performance was tested in the same manner as in Example 1. The results are shown in Table 1.

Example 6

The reaction solution of 0.05% NaClO, 0.01% NaI composition was adjusted to pH 2 using H ₂ SO ₄ in 20 ml, and the results were tested in the same manner as in Example 1, and the results are shown in Table 1. .

Example 7

The reaction solution of 0.05% NaClO, 0.01% NaI composition was adjusted to pH 5 using H ₂ SO ₄ in 20 ml, and the results were tested in the same manner as in Example 1, and the results are shown in Table 1. .

Example 8

The pH was adjusted to 8 using H ₂ SO ₄ in 20 ml of NaClO 0.05%, NaI 0.01% composition, and the results were tested in the same manner as in Example 1 and the results are shown in Table 1.

Example 9

After adjusting the pH to 10 using NaOH in a reaction solution of NaClO 0.05%, NaI 0.01% composition using NaOH, the performance was tested in the same manner as in Example 1 and the results are shown in Table 1.

Example 10

PH 20 was adjusted to 13 using NaOH in a reaction solution of NaClO 0.05% and NaI 0.01%, and the performance was tested in the same manner as in Example 1, and the results are shown in Table 1.

Example 11

20 ml of solution was added to 0.2 g of activated carbon (Samcheonli, SG100) by adding a solution of Ca (ClO) ₂ 5%, BaI ₂ 0.2%, VF 0.05%, phosphoric acid 0.2g and disodium hydrogen phosphate 2g. Exhaust gas containing 1000 ppm of nitrogen oxide, 600 ppm of sulfur oxide, 0.1 ng / ml of aromatic halokene compound (1,2-Dichlorobenzene), and 4% in O ₂ mass ratio was passed through at a flow rate of 100 cc / min. The removal capacity of nitrogen oxide and sulfur oxide was measured by the same method as described above, and the concentration of the aromatic halogen compound was measured by using a gas chromatography system equipped with an electron trap detector by collecting 200 µl of the gas that passed through the reaction slurry. The removal capacity was calculated by the equation.

Aromatic halogen compound removal rate (%)

= (Inlet Aromatic Halogen Compound Concentration-Outlet Aromatic Halogen Compound Concentration) / (Inlet Aromatic Halogen Compound Concentration) X 100 (%)

The results are shown in Table 1.

Example 12

A solution of 20 ml of NaClO 20%, LiBr 0.5%, NiI ₂ 0.25%, NaOH 9% was added to a mixed powder of 3 g of ovarian powder and 4 g of natural zeolite (Changno Chemical CLINOPTILOLITE). This was tested in the same manner as in Example 1 and the results are shown in Table 1.

Example 13

0.5 g of pearlite (Samson Co., Ltd., SB403) artificial bentonite (WG HYG2000) 0.5 g of KClO ₃ 0.05%, KClO 0.05%, MgF ₂ 0.01%, sodium bicarbonate 0.2g, sodium carbonate 0.2g, polymer dispersant 0.01% A 20 ml slurry solution was prepared by adding a solution of (strength emulsification, C) composition. This was tested in the same manner as in Example 1 and the results are shown in Table 1.

Example 14

After diluting 10 g of NaClO 0.3%, KMnO ₄ 0.1%, KI 0.05%, KOH 0.02%, and formic acid 0.01%, 10 g of the composition solution was carried on a mixed powder of 50 g of steelmaking slag powder and 50 g of titanium dioxide powder (Dupont), and then it was supported. The reaction sample was prepared by drying under reduced pressure at 1 ℃, ℃. 100 mg of the prepared reaction sample was taken and filled into the powder reactor as shown in FIG. 4, and the nitrogen gas and sulfur oxide removal capability was measured at the mixed gas concentration and flow rate as in Example 1 while maintaining a constant temperature of 200 ° C. FIG. The results are shown in Table 1.

Example 15

After diluting 100 g of a solution of 30% KClO ₃ , 0.5% LiBr, 0.5% KI, and 20% NaOH, the mixture was mixed with a mixed powder of 500 g of CaCO ₃ (Omiya) and 500 g of kaolin (domestic). The powder sample was removed by vacuum drying under pressure. This was tested in the same manner as in Example 15, and the results are shown in Table 1.

Example 16

1 g of a solution of 20% NaClO, 1% LiBr, 0.5% NiI ₂ , and 9% NaOH was taken, immersed in 1 g of ovarian powder, 0.5 g of fly ash, 1 g of natural zeolite, and evaporated at 40 ° C. for 30 minutes. Dried. This was tested in the same manner as in Example 15, and the results are shown in Table 1.

Example 17

2 g of a solution of 30% KClO ₃ and 3% LiI was mixed, mixed with 1.5 g of Ca (OH) ₂ (Dongyang Bentonite SP) and 0.5 g of the ovarian powder, followed by instant drying at 200 ° C. Experimental performance in the same manner as in and the results are shown in Table 1.

Example 18

100 kg of KClO _3, 5% KClO, 0.01% MgBr ₂ , 1% Acetate, 1% Sodium Acetate is injected into a wet scrubber where 10㎥ of water is circulated and injected, and exhausted at a rate of 5,000N㎥ / hr. At this time, the temperature of the circulating water circulated was 60 ° C., the temperature of the exhaust gas was 150 ° C., and the exhaust gas composition was NO 300 (± 50) ppm, SO ₂ 200 (± 30) ppm, HCl 100 (± 20) ppm and CO 300 (± 60) ppm O ₂ 7.5 (± 1)%. The concentrations of nitrogen oxides, sulfur oxides and carbon monoxide in the exhaust gas were measured using a flue gas analyzer (Testo 350, Testo, Germany), and the removal capacity was calculated by the following equation.

NOx removal rate (%) = (NO concentration before reaction-NO concentration after reaction) / (NO concentration before reaction) X 100 (%)

Sulfur oxides removal efficiency (%) = (SO ₂ concentration before reaction After reaction concentration of SO ₂₎ / (SO ₂ concentration before reaction) X 100 (%)

% Removal of carbon monoxide = (CO concentration before reaction-CO concentration after reaction) / (CO concentration before reaction) X 100 (%)

In addition, HCl was measured by absorbing light at around 460 nm using a photospectrophotometer using a thiocyanate mercury method in an air pollution process test method.

The removal capacity was calculated by the following equation from the sulfur oxide concentration determined by the above equation.

Hydrogen chloride removal rate (%) = (HCl concentration before reaction-HCl concentration after reaction) / (HCl concentration before reaction) X 100 (%)

The results are shown in Table 1.

Example 19

Ca (ClO) ₂ 3%, KI 0.5%, Citric Acid 0.05% and Potassium Citrate 0.1%, Ca (OH) ₂ 20%, Artificial Bentonite (Wyoming HYG2000) 5%, Polymer Dispersant 0.1% (Centrifuge, C) 100 kg of the liquid slurry was injected into a semi-dry reactor at 200 ° C. and reacted with the exhaust gas discharged at a rate of 10,000 Nm 3 / hr, where the exhaust gas composition was NO 250 (± 50) ppm and SO ₂ 150 (± 30) ppm, HCl 120 (± 20) ppm, CO 200 (± 60) ppm O ₂ 11 (± 2)% and reacted with the same exhaust gas. The results are shown in Table 1.

Example 20

A powder mixed with fly ash and activated silica in a 1: 1 weight ratio was sprayed with a powder containing 5% NaClO, 0.05% LiBr, 0.1% NiI ₂ , and 0.9% NaOH at 50 kg / hr in front of a bag filter at 170 ° C. And reacted with the exhaust gas discharged at a rate of 10,000 Nm3 / hr, at which time the composition of the exhaust gas was NO 150 (± 50) ppm, SO ₂ 300 (± 30) ppm, HCl 70 (± 20) ppm, CO 350 (± 60) ppm O ₂ 9 (± 2)%, and the performance was tested in the same manner as in Example 18 and the results are shown in Table 1.

Example 21

Powder prepared by mixing KClO ₃ 5%, MgBr ₂ 0.04%, NaOH 0.4% solution, synthetic zeolite (zeolite Y), and pearlite (Samson SB403) at a weight ratio of 1: 6: 6 to 50 kg / hr. The exhaust gas was discharged at a rate of 10,000 Nm3 / hr in a dry reactor at 190 ° C. At this time, the composition of the exhaust gas was NO 150 (± 50) ppm, SO ₂ 300 (± 30) ppm, and HCl 70 (± 20) ppm, CO (350 (± 60) ppm O ₂ 9 (± 2)%), the performance was tested in the same manner as in Example 18 and the results are shown in Table 1.

Example 22

5 kg of the solution of Example 4 and 50 kg of powder mixed with zeolite (Y), pearlite and Ca (OH) ₂ : 1: 1 by weight were sprayed simultaneously through different nozzles at the front of the electrostatic precipitator at 300 ° C. for 1 hour. It reacted with the exhaust gas discharged at 10,000Nm3 / hr, and the exhaust gas composition was NO 250 (± 50) ppm, SO ₂ 150 (± 30) ppm, HCl 120 (± 20) ppm, CO 200 It was (± 60) ppm O ₂ 11 (± 2)%, the performance was tested in the same manner as in Example 18 and the results are shown in Table 1.

Comparative Example 1

Dilute H ₂ SO ₄ solution was added to 20 ml of the reaction solution of 0.05% NaClO, and the pH was adjusted to 8. The results were measured in the same manner as in Example 1 and compared with Example 8. The results are shown in Table 1. .

Comparative Example 2

10 g of NaClO 0.3%, KMnO ₄ 0.1%, KOH 0.02%, and formic acid 0.01% were diluted 10-fold and supported on a mixed powder of 50g of steelmaking slag powder and 50g of titanium dioxide powder (Dupont), and then at 100 ° C and 1torr. The reaction sample was prepared by drying under reduced pressure. The reaction sample was tested in the same manner as in Example 15 to compare with Example 15, and the results are shown in Table 1.

Comparative Example 3

After preparing 20 ml of a solution of Ca (ClO) ₂ 5%, BaI ₂ 0.2%, VF 0.05%, 0.2 g phosphoric acid and 2 g disodium phosphate, the performance was measured in the same manner as in Example 11, and in particular, Example Comparison was made with the dioxin removal rate of 11 products (slurry in which activated carbon was dispersed in a solution of the same composition), and the results are shown in Table 1.

[Comparative Example 4]

20 mL of a reaction solution of 5% Ca (ClO) ₂ , 0.5% BaI ₂ , and 0.1% VF ₄ was prepared, and the removal rate of nitrogen oxide was measured in the same manner as in Example 1, and the nitrogen oxide was 80% or more. The duration to be removed was measured and compared with Example 3, and the results are shown in Table 1.

No removal rate (%) SO ₂ removal rate (%) Dioxin removal rate (%) (1.2-Dichloro benzen) HCl removal rate (%) CO removal rate (%) Duration ** (minutes) Example 1 100.0% 100% - - - Example 2 95.0% 90% - - - Example 3 99.0% 93% - - - 45 minutes Example 4 97.0% 99% - - - Example 5 90.0% 90% - - - Example 6 95.0% 70% - - - Example 7 99.0% 90% - - - Example 8 95.0% 99% - - - Example 9 85.0% 99% - - - Example 10 75.0% 99% - - - Example 11 99.0% 90% 99.9% - - Example 12 99.0% 99% - - - Example 13 85.0% 95% - - - Example 14 93.0% 95% - - - Example 15 85.0% 99% - - - Example 16 99.0% 98% - - - Example 17 100.0% 99% - - - Example 18 90.0% 99% - 99% 60% Example 19 92.0% 97% - 99% 55%

Table 1 continued

Example 20 84.0% 87% - 92% 50% Example 21 87.0% 85% - 90% 30% Example 22 85.0% 90% - 93% 40% Comparative Example 1 30.0% 99% - - - Comparative Example 2 40.0% 97% - - - Comparative Example 3 99.0% 90% 50.0% - - Comparative Example 4 90.0% 95% 15 minutes ** Duration of removal efficiency that removes nitrogen oxide (NO) continuously over 80%

The present invention provides a remover capable of removing not only nitrogen oxides but also other acid gases, such as hydrogen chloride and sulfur oxides, carbon monoxide and dioxins, in a simple and convenient single process of spraying a liquid (aqueous solution), powder or slurry. In addition, the present invention provides a method for removing harmful gases such as nitrogen oxide contained in the exhaust gas by using the remover.

The removal agent of the present invention can be applied to a simple process compared to the process of removing nitrogen oxides contained in the exhaust gas by using a conventional oxidant, the oxidation efficiency is improved to reduce the amount of expensive oxidant to reduce the cost It is excellent in oxidizing power and absorption of nitrogen oxides in almost all pH ranges. Therefore, these removers are not very constrained by the applied pH and therefore have very high flexibility for the application. In addition, by using the remover of the present invention, it is possible to effectively remove nitrogen oxides from the exhaust gas without incurring an expensive catalyst tower or exhaust gas heating cost (energy cost), and the conventional wet and (half) dry alkali absorption tower Since the process such as bag filter, electrostatic precipitator and cyclone is used as it is, no additional process is required. That is, the applicability is excellent. In addition, the remover of the present invention is applicable to a wide temperature range from room temperature to a high temperature of 500 ℃.

Claims (17)

A remover for removing nitrogen oxide contained in exhaust gas containing an oxidizing agent and a metal halogen compound. The remover of claim 1, further comprising a diluent. The remover of claim 2, wherein the diluent is water, an inorganic powder, or a mixture of water and an inorganic powder, and the form of the remover is an aqueous solution, a powder, or a slurry. 4. The remover of claim 3, wherein the amount of the oxidant is at least 0.02% by weight, and the amount of the metal halide compound is in the range of 1 to 40% by weight relative to the oxidant. The remover of claim 3, wherein the remover further comprises a base or a buffer. 5. The method of claim 5, wherein the base or buffer solution is sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, sodium bicarbonate, boric acid and salts thereof, formic acid and salts thereof, phthalic acid and salts thereof, lactic acid and salts thereof, malic acid At least one selected from the group consisting of salts thereof, tartaric acid salts thereof, glycolic acid salts thereof, succinic acid salts thereof, oxalic acid salts thereof, phosphoric acid salts thereof, acetic acid salts thereof, and citric acid salts thereof Remover for removing nitrogen oxide contained in the exhaust gas, characterized in that. According to claim 3, The inorganic powder is CaCO ₃ , CaO, Ca (OH) ₂ , CaCl ₂ , natural or artificial bentonite, activated alumina, activated silica, fly ash, slag, titanium dioxide, clay, volcanic ash, natural or artificial zeolite At least one selected from the group consisting of activated carbon, pearlite, and turbulent powder. The remover of claim 3, wherein the remover is in a range of pH 4 to pH 14. 4. The remover of claim 3, wherein when the remover is in a slurry state, the content of solids in the remover is in a range of 0.5 to 50 wt%. 4. The remover of claim 3, wherein when the remover is in a slurry state, the remover further comprises a polymer dispersant for preventing precipitation of the slurry and improving dispersion. . 4. The method of claim 3, wherein when the remover is in a powder state, the inorganic powder included in the remover supports the oxidizing agent and the metal halide compound or is simply mixed as a diluent, and evaporated or vacuum dried at a temperature of 200 ° C or lower. Remover to remove nitrogen oxides contained in the exhaust gas characterized in that the pulverized. The exhaust gas of claim 1, wherein the oxidizing agent is at least one selected from the group consisting of NaClO, NaClO ₂ , NaClO ₃ , KBrO ₃ , KClO ₃ , Ca (ClO) ₂ , and KMnO ₄ . Remover to remove nitrogen oxides contained. According to claim 1, wherein the metal halide compound (MX) is M is an alkali metal, alkaline earth metal or transition metal, Li, Na, K, Be, Mg, Ca, Ba, Sr, V, Cr, Mn, Fe, Nitrogen contained in the exhaust gas, wherein the nitrogen gas is selected from the group consisting of Co, Ni, Cu, and Zn, and X is at least one metal halide compound selected from the group consisting of F, Cl, Br, and I. Remover to remove oxides. Introducing a wet scrubber into the exhaust gas containing nitrogen oxides, The nitrogen oxide contained in the exhaust gas is oxidized by injecting the liquid removing agent of any one of claims 1 to 6, 8, 12, and 13 into the exhaust gas introduced from the wet scrubber. Absorbing the nitrogen oxide in a stable form into the liquid remover, and Exhausting the exhaust gas from which the nitrogen oxides have been removed, and recovering the liquid remover absorbing the nitrogen oxides from the wet scrubber. 15. The method of claim 14, wherein the liquid scrubber absorbing nitrogen oxide contained in the exhaust gas in the wet scrubber alkali metal sulfide, alkaline earth metal sulfide, NaHSO, Na ₂ SO ₃ , Na ₂ SO ₄ , Na ₂ S ₂ O _{3 , K 2 SO 3, Na 2} C 2 O 4, H 2 C 2 O at least one reducing agent selected from the group consisting of ₄ nitrogen oxides dissolved in the aqueous solution added (NO _x) gas nitrogen (N ₂₎ The method for removing nitrogen oxides from the exhaust gas further comprising the step of reducing. Passing an exhaust gas comprising nitrogen oxides through a (semi) dry reactor, a bag filter, a dry or wet electrostatic precipitator or a cyclone, Claim 1 to claim 13 of the powder or remover in the form of a slurry or inorganic powder and the liquid remover of any one of claims 1 to 13 at the same time (semi) dry reactor, (semi) dry Oxidizing the nitrogen oxides in the exhaust gas by spraying the front end of the reactor, the front end of the bag filter, the front end of the dry or wet electrostatic precipitator, or the front end of the cyclone to absorb or adsorb the nitrogen oxide in a stable form to the remover; and A method of removing nitrogen oxides from exhaust gas, comprising: exhausting the exhaust gas from which the nitrogen oxides have been removed, and recovering a remover that absorbs or adsorbs the nitrogen oxides. 17. The method of claim 14 or 16, wherein the temperature of the front end of the wet scrubber, the (semi) dry reactor, the bag filter, the front end of the dry or wet electrostatic precipitator or the front end of the cyclone is in the range of 50 to 400 ℃. A method of removing nitrogen oxides from exhaust gas.