KR101780750B1 - Reduction Solution for the Removal of Nitrogen Oxide Using Aniline Wastewater and Manufacturing Method the Same - Google Patents

Abstract

The present invention relates to a solution used in selective non-catalytic reduction with respect to nitrogen oxide and, more specifically, to a reduction solution for nitrogen oxide using aniline wastewater and a manufacturing method thereof. The reduction solution is manufactured by using aniline wastewater, easily adjusts the reaction temperature in operation and reduces the usage of urea or ammonia, thereby being manufactured at low costs compared to an existing reduction solution and having excellent performance.

Description

TECHNICAL FIELD The present invention relates to an aniline wastewater and a method for producing the same,

The present invention relates to a nitrogen oxide reduction solution for removing nitrogen oxide generated in an incinerator, and more particularly, to a solution used for selective non-catalytic reduction of nitrogen oxide, Aniline wastewater is used to make it easy to control the reaction temperature during operation and to reduce the amount of urea or ammonia to reduce the amount of nitrogen oxides by using aniline wastewater, And a method for producing the same.

Exhaust gas is discharged from various incinerators such as thermal power plants or waste disposal sites. Nitrogen oxides (NOx) contained in the exhaust gases are nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ) and nitrous oxide (N ₂ O ), And if it is discharged without any treatment, it becomes a representative environmental pollutant causing air pollution. For example, nitrogen monoxide acts as a causative substance of acid rain, causes urban smog, and is absorbed in a human respiratory tract, which can lead to bronchial inflammation and death when exposed to high concentrations. Nitrous oxide is a major source of global warming .

Nitrogen oxides are generated when fossil fuels are burned at high temperatures. Separate control is required to prevent air pollution. Control methods for such nitrogen oxides are largely controlled by controlling the combustion conditions to reduce the emission concentration, There is a way to do post-processing before it happens.

However, in the case of the control method of the combustion condition, it is not considered as an effective control method due to the limit of the reduction concentration and the emission allowance standard which is strengthened. As a result, the selective catalyst reduction method using the post- And a selective non-catalytic reduction method.

Selective catalytic reduction using a catalyst is a method of converting the nitrogen oxides into harmless nitrogen and water vapor by inducing the adsorption of the reducing agent and the reaction between the nitrogen oxides at the active sites of the catalyst surface. Such a selective catalytic reduction method has a high removal efficiency but a short period of use and requires disposal of used catalysts.

On the other hand, the selective non-catalytic reduction method is a method in which NO is reduced to N ₂ by directly spraying a reducing agent containing urea water or ammonia water at various points in the middle of the exhaust path of an incinerator. This selective non-catalytic reduction method has advantages over the selective catalytic reduction method because it has a long period of use and requires no additional facilities, thus providing installation / maintenance. However, in comparison with the selective catalytic reduction method, the efficiency of reducing nitrogen oxides is low and the temperature range for exhibiting high removal efficiency of nitrogen oxides is narrowly limited to about 900 to 1,000 DEG C, so that the removal efficiency is significantly lowered at a lower temperature, The reduction rate of the injected reducing agent is increased and the reduction reaction of the nitrogen oxide is not properly induced.

That is, in the case of the selective non-catalytic reduction method, the conversion rate is improved only within a narrow temperature range. If the urea water or ammonia water is directly sprayed to the exhaust gas, the temperature of the exhaust gas is rapidly lowered, A problem that can not be easily occurred occurs.

Also, the urea water or ammonia water is an expensive material, and the production cost of the reducing solution increases accordingly.

Korean Patent No. 10-0393322

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to enlarge the reaction temperature range effective for conversion of NO to N ₂ , thereby making it easy to control the reaction temperature in the nitrogen oxide reduction process, the while reducing NO improve the percentage that is converted to N ₂ and NO, while having excellent performance such that a side reaction which is converted to N ₂ O is suppressed using aniline wastewater to reduce production costs as compared to conventional reducing solution sanctions There is provided a nitrogen oxide reduction solution and a production method thereof.

According to one aspect of the present invention, there is provided a nitrogen oxide reduction solution comprising 4.5 to 5.5 wt% of urea or ammonia, 45 to 55 wt% of aniline wastewater and 40.5 to 49.5 wt% of water, wherein the aniline wastewater is a hydrochloric acid (HCl) A mixture of MDA (4,4-Methylene Dianiline: CH ₂ (C ₆ H ₄ NH ₂ ) ₂ ) was prepared by reacting formalin (CH ₂ O) with an excess of aniline (C ₆ H ₅ NH ₂ ) and the caustic effluent is neutralized with (NaOH) and collected to give the MDA, Ca ^{2 +} (calcium ion) 0.9 ~ 1.1mg / L, K + ( potassium ion) 11 ~ 13mg / L, Na + ( sodium ion) ^{8,820 ~ 10,780mg / L, Cl -} ( chlorine ions) 24 ~ 30mg / L, NO 3 - ( nitrate) _{1,802 ~ 2,203mg / L, SO 4} 2- ( sulfate ^{_{ion) 4,006 ~ 4,897, HCO 3 -}} ( bicarbonate ions) 4,731 ~ 5,283mg / L, CO 3 2- ( carbonate ion) 1,177 ~ 1,439mg / L, OH - (Hydroxide ion) of 0.9 to 1.1 mg / L, and NH ₄ ⁺ (ammonium ion) of 71 to 87 mg / L.

According to another aspect of the present invention there is provided a process for the preparation of 4,4-methylenedianiline: CH ₂ (C ₆ H ₄ ) by reacting formalin (CH ₂ O) with an excess of aniline (C ₆ H ₅ NH ₂ ) NH ₂ ) ₂ ) mixture, neutralizing the MDA mixture with caustic soda (NaOH), purifying the MDA, and recovering the aniline wastewater; And at least one of aniline wastewater, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH), and water to prepare a nitrogen oxide reduction solution; The present invention also provides a method for producing a nitrogen oxide reduction solution using aniline wastewater.

According to a preferred feature of the present invention, the step of injecting ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ) and ferrous sulfate (FeSO ₄ ) into the recovered aniline wastewater while irradiating ultraviolet .

According to the NOx reduction Solution of aniline waste water of the present invention, when the aniline effluent from MDI batches step height after oxidation treatment urea or mixed with ammonia, urea or the nitrogen oxide NO while reducing the amount of ammonia it is N ₂ And the side reaction in which NO is converted to N ₂ O is suppressed. Thus, it is possible to reduce the production cost as compared with the conventional reducing solution preparation while having excellent performance.

Further, by expanding the effective reaction temperature range for converting NO to N ₂ , the temperature can be easily controlled in the nitrogen oxide reduction treatment process as compared with the conventional reducing solution preparation, and the conversion ratio can be further improved.

1 is a schematic diagram of an aniline waste water recovery process in an MDI production process.
FIG. 2 is a graph showing NO conversion ratios of the nitrogen oxide reduction solution according to the present invention and Comparative Example.
FIG. 3 is a graph showing the N ₂ O production concentration of the nitrogen oxide reduction solution according to the embodiment of the present invention and the comparative example according to the temperature range.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the following embodiments. In addition, to include an element throughout the specification does not exclude other elements unless specifically stated otherwise, but may include other elements.

The method for producing a nitrogen oxide reduction solution using aniline wastewater according to the present invention comprises reacting formalin (CH ₂ O) with an excess of aniline (C ₆ H ₅ NH ₂ ) under a hydrochloric acid (HCl) : Preparing a mixture of CH ₂ (C ₆ H ₄ NH ₂ ) ₂ ), neutralizing the MDA mixture with caustic soda (NaOH), purifying the MDA and then recovering the aniline wastewater, ozone (O _3), hydrogen peroxide (H ₂ O ₂₎ and the step of the ferrous sulfate (FeSO4) implanted in the recovered aniline waste water to remove the odor and aniline waste water, components ((NH _{2) 2} CO) or ammonia (NH ₄ OH) and water to prepare a nitrogen oxide reduction solution.

1 is a schematic diagram of an aniline waste water recovery process in an MDI production process.

Retrieving the aniline waste water, hydrochloric acid (HCl) under formalin catalyst (CH ₂ O) to an excess of the aniline (C ₆ H ₅ NH ₂₎ is reacted with _{MDA (4,4-MethyleneDianiline: CH 2} (C 6 H ₄ NH ₂ ) ₂ ) mixture, neutralizing the MDA mixture with caustic soda (NaOH), separating the organic material layer containing MDA, purifying the organic material layer, and recovering the aniline wastewater from which the organic material has been extracted have.

Conventionally, manufacturers of methylene diphenyl diisocyanate (MDI) have spent a great deal of money to dispose or dispose of aniline wastewater, which is essential in the MDI manufacturing process. The present invention provides a method for recovering aniline wastewater that is essentially generated in the MDI manufacturing process and using it as a nitrogen oxide reduction solution prepared by mixing it with urea ((NH ₂ ) ₂ CO) water or ammonia (NH ₄ OH) water Thereby benefiting MDI manufacturers to reduce the cost of treating / disposing aniline wastewater.

The aniline waste water has Ca ^{2 +} (calcium ion) 0.9 ~ 1.1mg / L, K + ( potassium ion) 11 ~ 13mg / L, Na + ( sodium ion) 8,820 ~ 10,780mg / L, Cl - ( chlorine ions) 24 ~ 30 mg / L, NO ₃ ^- (nitrate ion) _{1,802 ~ 2,203mg / L, SO 4} 2- ( sulfate ^{_{ion) 4,006 ~ 4,897, HCO 3 -}} ( bicarbonate ions) 4,731 ~ 5,283mg / L, CO 3 2- ( carbonate ion) 1,177 ~ 1,439mg / L, OH - (Hydroxide ion) of 0.9 to 1.1 mg / L and NH ₄ ⁺ (ammonium ion) of 71 to 87 mg / L, and other nitrogen compounds (Total Nitrgen Chemicals) of 1,339 to 1,592 mg / L and Suspended Solid 34 to 42 mg / L may be included.

The aniline wastewater has an alkalinity of 3,600 to 4,400 eq / l and a CODcr (chemical oxygen demand by potassium dichromate) of 1,830 to 2,238 mg / L.

The aniline wastewater recovered according to the present invention may contain organic substances such as C12-Lactone, 2-ethylhexanol-diol-butyrate and butyric acid, The chromaticity needs to be corrected for the rejection of wastewater recycling or the improvement of the merchantability.

Alternatively, the method for producing a nitrogen oxide reduction solution using aniline wastewater according to the present invention may further comprise the step of adding ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ) or ferrous sulfate (FeSO ₄ ) while irradiating ultraviolet And injecting the recovered aniline wastewater to remove the odor.

Ultraviolet irradiation, hydrogen peroxide or ferrous sulfate acts as an ozone oxidizing agent, and it is possible to irradiate only ozone with ultraviolet rays, or add at least one of hydrogen peroxide or ferrous sulfate to ozone, but it is preferable to inject both hydrogen peroxide and ferrous sulfate It is most effective for organic matter decomposition (maximum decomposition rate: 96%) and chromaticity correction (maximum removal rate: 100%) in a short time because it increases the amount of generated hydroxyl radicals.

The ozone injection flow rate may be from 0.026 to 0.053 g / min, and when injected at a rate of 0.053 g / min or more, the organic material removal rate is slowed, so it is preferable that the injection rate is 0.053 g / min.

The injection concentration of hydrogen peroxide may be from 5 to 25 mM, and the organic matter removal rate and the chromaticity correction effect are not greatly improved when the concentration is more than 10 mM. This is presumed to be due to the fact that hydrogen peroxide forms a peroxide radical at a concentration of 10 mM or more, thereby lowering the reactivity of the hydroxyl radical.

The injection concentration of ferrous sulfate may be 0.04-0.1 mM, and it is preferable that the concentration of 0.1 mM is injected because the organic matter removal rate is lower than 0.1 mM. This is presumably because ferrous sulfate acts as a scavenger of hydroxyl radicals at concentrations of 0.1 mM or higher.

The method for producing a nitrogen oxide reduction solution using aniline wastewater according to the present invention is characterized by mixing at least one of aniline wastewater, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH) .

The aniline wastewater refers to wastewater that has been pretreated selectively as it is recovered or for removing odors.

The nitrogen oxide reduction solution according to the present invention is prepared by mixing 4.5 to 5.5 wt% of at least one of aniline wastewater 45 to 55 wt%, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH) and 40.5 to 49.5 wt% .

According to the invention the recovered aniline waste water has Ca ^{2 +} (calcium ion), K ⁺ (potassium ion), Na ⁺ (sodium ion), and NH ₄ ⁺ (ammonium ion) it is the metal ion containing a large amount such as the element or ammonia promotes the hydrolysis, Cl ^- (chloride ion), NO ₃ ^- (nitrate), SO ₄ ^2- (sulfate ion), HCO ₃ ^- (bicarbonate ions), CO ₃ ^2- (carbonate ions) and OH ^- (Hydroxide ion), it provides pH optimum condition suitable for urea or ammonia hydrolysis, so NO -> N ₂ maximum conversion rate is increased and effective conversion rate temperature range is expanded and NO -> N ₂ O side reaction is also inhibited.

4.5 to 5.5 wt% of at least one of the elements ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH) can be used. If the amount is less than 4.5 wt%, the effect of NO-> N ₂ conversion is insignificant. wt.%, the NO -> N ₂ conversion effect does not increase.

Aniline wastewater can be used in 45 ~ 55wt%. If it is used less than 45wt%, the NO -> N ₂ maximum conversion rate increase effect will not occur and the NO -> N ₂ maximum conversion rate will increase even if it is used in excess of 55wt% Do not increase.

Experimental Example

The nitrogen oxide reduction solutions according to Examples and Comparative Examples of the present invention are as follows. The example is a nitrogen oxide reduction solution according to the present invention prepared by mixing 5wt% of element, 50wt% of aniline wastewater and 45wt of water. The comparative example is a conventional nitrogen oxide reduction solution prepared by mixing 5wt% of element and 95wt% of water to be.

FIG. 2 is a graph showing NO conversion ratios of the nitrogen oxide reduction solution according to the present invention and Comparative Example.

The current regulations regulate the NO -> N ₂ conversion rate of the incinerator to be more than 60%, so 60% is referred to as the effective conversion rate.

2, the maximum conversion rate of the nitrogen oxide reduction solution according to the comparative example is 82% at 964 ° C and the effective conversion rate achievable temperature range is 900 to 1,030 ° C, while the maximum conversion rate of the nitrogen oxide reduction solution according to the embodiment The conversion rate is 96% at 914 占 폚 and the effective conversion rate achievable temperature range is 700 to 1,030 占 폚. Compared with the comparative example, the maximum conversion rate is improved from 82% to 96% by 17% in the case of the embodiment, so that the present invention has an advantageous effect of reducing the use amount of the nitrogen oxide reduction solution by 17%.

As compared with the comparative example, the effective conversion rate is extended by about 300% at a temperature range of 130 ° C. (= 1,030 - 900 ° C.) -> 330 ° C. (= 1,030 - 700 ° C.), so that the temperature control process of the incinerator exhaust gas And it has an advantageous effect that can be facilitated.

Current regulations regulate NO -> N ₂ conversion rates in incinerators but are indifferent to the emission of N ₂ O, another major contributor to fine dust. Although undesirable, when a urea or ammonia is used as a nitrogen oxide reducing agent, a NO -> N ₂ O side reaction also occurs.

FIG. 3 is a graph showing the N ₂ O production concentration of the nitrogen oxide reduction solution according to the embodiment of the present invention and the comparative example according to the temperature range.

As shown in FIG. 3, the maximum conversion rate of the nitrogen oxide reduction solution according to the embodiment is recorded while the N ₂ O generation concentration at 904 ppm is recorded at 964 ° C. at which the maximum conversion rate of the nitrogen oxide reduction solution according to the comparative example is recorded The N ₂ O production concentration at 914 ° C is 8 ppm.

Compared with the comparative example, in the case of the embodiment, the concentration of N ₂ O is reduced from 90 ppm to 8 ppm by 91.1%. Therefore, when the nitrogen oxide reduction solution according to the present invention is used, an advantageous effect of reducing the N ₂ O production rate by 91.1% .

The present invention is not limited by the above-described embodiments but is intended to be limited by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (3)

Or an ammonia, 4.5 to 5.5 wt% of ammonia, 45 to 55 wt% of aniline wastewater, and 40.5 to 49.5 wt% of water,
The aniline wastewater is reacted with formalin (CH ₂ O) with an excess amount of aniline (C ₆ H ₅ NH ₂ ) under a hydrochloric acid (HCl) catalyst to obtain MDA (4,4-Methylenedianiline: CH ₂ (C ₆ H ₄ NH ₂ ) ₂ ) Mixture, neutralizing the MDA mixture with caustic soda (NaOH) and purifying the MDA,
Ca ^{2 +} (calcium ion) 0.9 ~ 1.1mg / L, K + ( potassium ion) 11 ~ 13mg / L, Na + ( sodium ion) 8,820 ~ 10,780mg / L, Cl - ( chlorine ions) 24 ~ 30mg / L , NO ₃ ^- (nitrate ion) _{1,802 ~ 2,203mg / L, SO 4} 2- ( sulfate ^{_{ion) 4,006 ~ 4,897, HCO 3 -}} ( bicarbonate ions) 4,731 ~ 5,283mg / L, CO 3 2- ( carbonate ion) 1,177 ~ 1,439mg / L, OH - (Hydroxide ion) of 0.9 to 1.1 mg / L and NH ₄ ⁺ (ammonium ion) of 71 to 87 mg / L. A mixture of MDA (4,4-MethyleneDianiline: CH ₂ (C ₆ H ₄ NH ₂ ) ₂ ) was prepared by reacting formalin (CH ₂ O) with an excess of aniline (C ₆ H ₅ NH ₂ ) under a hydrochloric acid (HCl) Neutralizing the MDA mixture with caustic soda (NaOH), purifying MDA, and then recovering the aniline wastewater; And
Preparing a nitrogen oxide reduction solution by mixing at least one of aniline wastewater, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH), and water; And an aniline wastewater. 3. The method of claim 2,
Characterized by further comprising the step of injecting ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ) and ferrous sulfate (FeSO ₄ ) into the recovered aniline wastewater while irradiating ultraviolet rays (UV) A method for producing a nitrogen oxide reduction solution using wastewater.

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