KR101797744B1 - Reduction Solution for the Removal of Nitrogen Oxide Using TNT Wastewater and Manufacturing Method the Same - Google Patents

Abstract

Provided are a reduction solution for nitrogen oxide using 2,4,6-trinitrotoluene (TNT) wastewater, and a production method thereof. The reduction solution of the present invention is used in a selective non-catalytic reduction for nitrogen oxide, is produced by using TNT wastewater, and enables easy adjustment of a reaction temperature during an operation. By reducing consumption of urea or ammonia, the reduction solution requires low production costs compared to existing reduction solution preparations while ensuring superior functions.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a nitrogen oxide reduction solution using TNT wastewater,

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, TNT wastewater is used to make it easy to control the reaction temperature during operation and to reduce the amount of urea or ammonia used so that the TNT wastewater can provide excellent performance even at low manufacturing cost compared to the conventional reducing solution, 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, , TNT wastewater which can reduce the production cost compared to the conventional reducing solution material while having a superior performance by reducing the NO conversion to N ₂ and suppressing the side reaction in which NO is converted into N ₂ O, 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 4.5-5.5 wt% urea or ammonia, 45-55 wt% TNT wastewater and 40.5-49.5 wt% water, wherein the TNT wastewater is Crude (crude) The waste water recovered by decanting the washed TNT mixture after washing with TNT (C ₇ H ₅ N ₃ O ₆ ) aqueous solution of sodium sulfite (sodium sulfite: Na ₂ SO ₃ ), Ca ²⁺ (calcium ion) ~ 12.1mg / L, K ⁺ (potassium ion) 14.4 ~ 17.6mg / L, Mg + ( magnesium ion) 0.9 ~ 1.1mg / L, Na + ( sodium ion) 18,030 ~ 22,036mg / L, Si 4 - ( silicon ion) 2.7 ~ 3.3mg / L, Cl - ( chloride ion) 6.3 ~ 7.7mg / L, NO 3 - ( nitrate) 12,077 ~ 14,761mg / L, SO 4 2- ( sulfate) 12,260 ~ 14,9842mg / L, HCO ₃ ^- (bicarbonate ions) 94 ~ 116mg / L, CO 3 2- ( carbonate ion) 2,005 ~ 2,451mg / L, OH - ( hydroxide ion) 103 ~ 127mg / L, and NH ₄ ⁺ (ammonium ion) 52 To about 64 mg / L, based on the total amount of the TNT waste water.

According to another aspect of the invention, Crude _{(crude) TNT (C 7 H 5 N} 3 O 6) for Sodium sulfie: washed (sodium sulphite Na ₂ SO ₃₎ aqueous solution, by decanting the wash the TNT mixture TNT Recovering the wastewater; And at least one of TNT 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 TNT 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 TNT wastewater while irradiating ultraviolet .

According to the NOx reduction solution using TNT waste water of the present invention, by mixing with the TNT be an element after highly oxidized waste water or in aqueous solution coming out from TNT manufacturing unit processes, elements, or while reducing the nitrogen oxide NO to the amount of ammonia 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 a TNT waste water recovery process in a TNT manufacturing 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 preparing a nitrogen oxide reduction solution using TNT wastewater according to the present invention comprises the steps of washing Crude (crude) TNT (C ₇ H ₅ N ₃ O ₆ ) with an aqueous solution of sodium sulfite (sodium sulfite: Na ₂ SO ₃ ) Disinfecting the washed TNT mixture to recover TNT wastewater; injecting ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ), and ferrous sulfate (FeSO 4) into the recovered TNT waste water while irradiating ultraviolet (UV) And a step of preparing a nitrogen oxide reduction solution by mixing at least one of TNT wastewater, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH), and water.

1 is a schematic diagram of a TNT waste water recovery process in a TNT manufacturing process.

The step of recovering the TNT wastewater is performed by first washing Crude (crude) TNT (C ₇ H ₅ N ₃ O ₆ ) with an aqueous solution of sodium sulfite (sodium sulfite: Na ₂ SO ₃ ) . This TNT mixture includes TNT, dinitrotoluene (DNT), Nitrobenzene (NB) and hexannitrobibenzene (HNB), which can be decantered to recover TNT wastewater (aka red water).

Conventionally, TNT manufacturers have spent a great deal of money to dispose of or dispose of TNT wastewater, which is essential in the TNT manufacturing process. The present invention provides a method for recovering TNT wastewater which is essentially generated in a TNT 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 TNT manufacturers to reduce the cost of processing / disposing TNT wastewater.

The TNT wastewater is Ca ^{2 +} (calcium ion) 9.9 ~ 12.1mg / L, K + ( potassium ion) 14.4 ~ 17.6mg / L, Mg + ( magnesium ion) 0.9 ~ 1.1mg / L, Na + ( sodium ion) ^{18,030 ~ 22,036mg / L, Si 4} - ( silicon ion) 2.7 ~ 3.3mg / L, Cl - ( chloride ion) 6.3 ~ 7.7mg / L, NO 3 - ( nitrate) 12,077 ~ 14,761mg / L, SO 4 ^2- (sulfate ion) 12,260 ~ 14,9842mg / L, HCO 3 - ( bicarbonate ions) 94 ~ 116mg / L, CO 3 2- ( carbonate ion) 2,005 ~ 2,451mg / L, OH - ( hydroxide ion) 103 to 127mg / L and and NH ₄ ⁺ (ammonium ion) contain 52 ~ 64mg / L, other nitrogen compounds (Total Nitrgen Chemicals) 7,890 ~ 9,644mg / L and suspended organic matter (suspended Solid) can be included are 34 to 42mg / L have.

The alkalinity of the TNT wastewater is 3,600-4,400 eq / l, and the CODcr (chemical oxygen demand by potassium dichromate) may be 2,028-8,800 mg / L.

The TNT wastewater recovered in accordance with 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 TNT 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 TNT waste water 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.

Next, the method for producing a nitrogen oxide reduction solution using TNT wastewater according to the present invention comprises mixing TNT waste water, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH) .

The TNT wastewater refers to wastewater that has been pretreated as it is recovered or selectively treated for odor removal.

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 TNT wastewater 45 to 55 wt%, urea ((NH ₂ ) ₂ CO) or ammonia (NH ₄ OH) and 40.5 to 49.5 wt% .

The TNT wastewater recovered in accordance with the present invention contains metal ions such as Ca ^{2 +} (calcium ion), K ⁺ (potassium ion), Mg ⁺ (magnesium ion), Na ⁺ (sodium ion) and NH ₄ ⁺ (ammonium ion) It promotes a large amount it contains elements or hydrolysis of ammonia, Si ^{4 -} (silicon ions), Cl ^- (chloride ion), SO ₄ ^2- (sulfate ion), HCO ₃ ^- (bicarbonate ions), CO ₃ ^2- (Carbonate ion) and OH ^- (hydroxide ion), it provides optimal pH optimum for urea or ammonia hydrolysis, so NO -> N ₂ maximum conversion rate increases and effective conversion rate And the NO -> N ₂ O side reaction is also supposed to be suppressed.

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.

TNT wastewater available 45 ~ 55wt%, and NO as compared to using less than 45wt%, only elements in use - does not have> N ₂ up conversion synergistic effect, even if it exceeds 55wt% NO -> N ₂ is the maximum conversion rate synergism 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 TNT 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 95% at 912 ° C and the effective conversion rate achievable temperature range is 800 to 1,030 ° C. Compared with the comparative example, the maximum conversion rate is improved from 82% to 95% by 16% in the case of the embodiment, and thus the present invention has an advantageous effect of reducing the amount of the nitrogen oxide reduction solution used by 16%.

Compared with the comparative example, the effective conversion rate achievable temperature range is expanded by about 200% at 130 ° C (= 1,030 - 900 ° C) -> 230 ° C (= 1,030 - 800 ° 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 At 936 ° C, the N ₂ O production concentration represents 33 ppm.

Compared with the comparative example, since the N ₂ O production concentration is reduced from 90 ppm to 33 ppm by 63.3% in the examples, the use of the nitrogen oxide reduction solution according to the present invention can advantageously reduce the N ₂ O production rate by 63.3% .

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)

Urea or 4.5 to 5.5 wt% of ammonia, 45 to 55 wt% of TNT wastewater, and 40.5 to 49.5 wt% of water,
The TNT wastewater is wastewater recovered by washing the Crude (crude) TNT (C ₇ H ₅ N ₃ O ₆ ) with an aqueous solution of sodium sulfite (sodium sulfite: Na ₂ SO ₃ ) and then decanting the washed TNT mixture ,
Ca ^{2 +} (calcium ion) 9.9 ~ 12.1mg / L, K + ( potassium ion) 14.4 ~ 17.6mg / L, Mg + ( magnesium ion) 0.9 ~ 1.1mg / L, Na + ( sodium ion) 18,030 ~ 22,036mg / L, Si ^{4 -} (silicon ion) 2.7 ~ 3.3mg / L, Cl - ( chloride ion) 6.3 ~ 7.7mg / L, NO 3 - ( nitrate) 12,077 ~ 14,761mg / L, SO 4 2- ( sulfate L), OH ^- (hydroxide ion) 103-127 mg / L, and the like, and the amount of HCO ₃ ^- (bicarbonate ion) 94 to 116 mg / L, CO ₃ ^2- (carbonate ion) 2,005 to 2,451 mg / NH ₄ ⁺ (ammonium ion) in an amount of 52 to 64 mg / L. delete delete

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