Denitration agent composition, preparation method thereof and application of denitration agent composition in start-stop peak regulation of low-temperature boiler

Abstract

The invention relates to the technical field of air pollution control, in particular to a denitration agent composition and a preparation method thereof and application of the denitration agent composition in start-stop peak regulation of a low-temperature boiler, and the denitration agent composition comprises the following components in percentage by weight: 5%-20% of organic acid, 3%-10% of inorganic acid, 0.5%-5% of a surfactant, 1%-8% of a polyaniline compound, 2% of manganese sulfate and the balance of water. The preparation method comprises the following steps: S1, mixing the organic acid with the inorganic acid, and stirring at the temperature of 40-60 DEG C; s2, adding a surfactant and a polyaniline derivative, and continuously stirring for 1-2 hours at the speed of 200-500 rpm; s3, manganese sulfate is added, the PH is adjusted to be 3-4, and a stable composite solution is formed through electrochemical doping induction. The method has the advantages that polyaniline and heteropoly acid are compounded for low-temperature denitration for the first time, traditional high-temperature dependence is broken through, it is guaranteed that efficient operation is still conducted under the low-temperature condition of 25-90 DEG C, and the denitration efficiency is larger than or equal to 80%; according to the invention, the denitration cost is reduced by 20-30%, the catalyst replacement frequency is reduced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of air pollution prevention and control, and particularly relates to a denitration agent composition, a preparation method thereof, and an application of the denitration agent composition during start-up, shutdown, and peak regulation of a low-temperature boiler. Background Art

[0002] The existing SNCR / SCR technology has high temperature requirements and usually needs to operate effectively above 200°C. However, the denitration efficiency decreases significantly at low temperatures (such as 25°C - 90°C), and even completely fails. During start-up, shutdown, and peak regulation of the boiler, the flue gas temperature drops suddenly to 40°C - 90°C, resulting in the complete failure of the SNCR / SCR technology and the instantaneous NOx emission exceeding the standard by 2 - 3 times. The existing low-temperature denitration technology (such as the publication number CN112958153A) still requires a temperature above 200°C, and the solid catalyst is prone to deactivation and poisoning, which cannot meet the environmental protection requirements. In addition, the problems of equipment corrosion and side reactions under low-temperature conditions are serious, increasing the maintenance cost and equipment downtime. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a denitration agent composition, a preparation method thereof, and an application of the denitration agent composition during start-up, shutdown, and peak regulation of a low-temperature boiler, so as to solve the problem that the existing SNCR / SCR technology has high temperature requirements and cannot effectively solve the problem of low denitration efficiency at low temperatures of flue gas during start-up, shutdown, and peak regulation of the boiler.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: In the first aspect of the present invention, a denitration agent composition is provided, which includes the following components in weight percentages: organic acid 5% - 20%, inorganic acid 3% - 10%, surfactant 0.5% - 5%, polyaniline compound 1% - 8%, manganese sulfate 2%, and the balance is water or dimethylformamide.

[0005] Preferably, the organic acid is formic acid or acetic acid, the inorganic acid is sulfuric acid, the surfactant is AEO or AES, and the polyaniline compound includes polyaniline or derivatives.

[0006] In the second aspect of the present invention, a preparation method of a denitration agent composition is provided, which includes the following steps: S1: Mix the organic acid and the inorganic acid, and stir at 40°C - 60°C; S2: Add the surfactant and the polyaniline derivative, and continue to stir at a speed of 200 - 500 rpm for 1 - 2 hours; S3: Add manganese sulfate, adjust the pH to 3 - 4, and induce the formation of a stable composite solution through electrochemical doping.

[0007] Preferably, the denitration agent composition forms a heteropolyacid polynuclear complex through the connection of organic acids, inorganic acids and manganese ions by oxygen bridges, and the manganese ions are transformed from the low valence state of +2 to the high valence states of +3 and +4.

[0008] In the third aspect of the present invention, an application of a denitration agent composition is further provided. The denitration agent composition is used for catalytically reducing NO in flue gas during the start-up, shutdown and peak regulation of a low-temperature boiler at 25°C - 90°C.

[0009] Preferably, the application method is as follows: S1: Spray the denitration agent composition into the flue duct through an atomizing nozzle at a pressure of 0.3 - 0.5 MPa, and control the atomization particle size ≤ 50 μm; S2: Adjust the flue gas flow rate to 5 - 15 m / s, the baffle spacing to 1 / 5 - 1 / 3 mm, the reaction temperature to 25°C - 90°C, and the reaction time to 0.5 - 2 seconds; S3: Through the synergistic effect of heteropolyacid and polyaniline, complex and adsorb NO and reduce it to N2, H2O and CO2; S4: Dynamically adjust the injection amount of the denitration agent by using the PID algorithm to ensure that the denitration efficiency remains above 85% when the flue gas flow rate fluctuates by ±20%.

[0010] Preferably, an anti-corrosion coating PTFE is provided in the flue duct to resist the acidic corrosion of heteropolyacid.

[0011] Preferably, the conjugated π-electron system of polyaniline can promote electron transfer and accelerate the adsorption and reduction reactions of NO.

[0012] Compared with the prior art, the advantages of the present invention are as follows: 1. The present invention first combines polyaniline and heteropolyacid for low-temperature denitration, breaking through the traditional high-temperature dependence, ensuring efficient operation under low-temperature conditions of 25°C - 90°C, and the denitration efficiency ≥ 80%.

[0013] 2. The present invention reduces the denitration cost by 20% - 30%, reduces the catalyst replacement frequency, and extends the service life of the equipment. Description of the Drawings

[0014] Figure 1 is the equipment diagram used in the process of the present invention Figure 2 is the reaction mechanism involved in the denitration process of the present invention In the figure: 1. Gas turbine; 2. Boiler; 3. SCR denitration; 4. Agent A; 5. Agent B; 6. Control system; 7. Liquid medicine mixer; 8. Screw air compressor; 9. Atomized flue duct denitration system; 10. Chimney. Detailed Embodiments

[0015] To make the objectives and principles of the present invention clearer and more understandable, the following further elaborates in conjunction with the accompanying drawings and specific embodiments.

[0016] As mentioned above, the current existing SNCR / SCR technology has high temperature requirements and usually needs to operate effectively above 200°C. However, the denitration efficiency decreases significantly under low-temperature conditions and even completely fails. When the boiler starts, stops, or adjusts the peak load, the flue gas temperature drops suddenly, resulting in the complete failure of the SNCR / SCR technology and the instantaneous NOx emissions exceeding the standard by 2-3 times.

[0017] Based on the above problems, this embodiment provides a denitration agent composition, and its specific composition is 10% acetic acid, 3% sulfuric acid, 5% AEO-9, 1% AES, 8% polyaniline, 60% dimethylformamide, 2% manganese sulfate, and 13% electrolyzed water.

[0018] The specific preparation method of this denitration agent composition: Mix 10% acetic acid and 3% sulfuric acid, and stir at 40°C - 60°C; add 5% AEO-9 and 8% polyaniline, and continue to stir at a speed of 200 - 500 rpm for 1 - 2 hours; add 2% manganese sulfate, adjust the pH to 3 - 4, and induce the formation of a stable composite solution through electrochemical doping.

[0019] See Figure 1 , the application method of the denitration agent composition provided in this embodiment is as follows: The device includes a gas turbine 1, a boiler 2. The flue gas treated by SCR denitration 3 enters the atomizing flue gas denitration system 9. Agent A 4 and agent B 5 are mixed through a liquid medicine mixer 7. The control system 6 also includes a screw air compressor 8. After treatment, it enters the atomizing flue gas denitration system 9 and finally discharges from the chimney 10. The denitration agent composition of the present invention is sprayed into the flue through an atomizing nozzle at a pressure of 0.3 - 0.5 MPa, controlling the atomization particle size ≤ 50 μm, adjusting the flue gas flow rate to 5 - 15 m / s, the baffle plate spacing to 1 / 5 - 1 / 3 mm, the reaction temperature to 25°C - 90°C, the reaction time to 0.5 - 2 seconds, and using the PID algorithm to dynamically adjust the injection amount of the denitration agent to ensure that the denitration efficiency remains above 85% when the flue gas flow rate fluctuates by ±20%, and an anti-corrosion coating PTFE is set in the flue to resist the acidic corrosion of heteropolyacid.

[0020] See Figure 2, Principle of the present invention during denitrification: The denitrification agent composition is a polynuclear complex (IUPAC) formed by organic acids, inorganic acids and metal ions connected by oxygen bridges. The heteropolyacid denitrification solution is acidic, has redox properties, and is a multifunctional solution with good stability. It can be used in homogeneous reactions, is easily soluble in substances such as water and organic solvents, and shows high-performance co-catalytic ability. It has good thermal stability. When the heteropolyacid anions, cations, protons, and metal manganese ions undergo a reduction reaction by acidic substances such as polyaniline (PANI) during redox, the manganese ions (Mn2+) change from a low valence state (+2) to a high valence state (+3, +4). Polyaniline, as a nitriding agent, promotes the oxidation of Mn2+ to generate high-valence +3 and +4 ions, and at the same time, polyaniline is reduced. This process involves a catalyst for redox reactions of electron transfer oxidation intensity. Organic cations and crystal water or dimethylformamide (DMF) are good solvents. Compared with other solvents, it can improve the reaction efficiency. Aromatic aldehydes with electron-withdrawing groups can smoothly carry out the reduction of NO reaction, correspondingly improving the efficiency of N-phenylamine. For the denitrification rate of aromatic aldehydes and amines with electron-withdrawing groups such as NO2, the NO2 group undergoes reduction during the reaction. The denitrification agent composition provided in this example can decompose and reduce NO to generate N2, which is achieved by accelerating the catalysis through the synergistic effect of heteropolyacid and polyaniline. Nitric oxide generates azide, and the azide reaction rate is extremely fast, generating N2, H2O, and CO2. The denitrification agent composition is a polynuclear complex (IUPAC) formed by organic acids, inorganic acids and metal ions connected by oxygen bridges.

[0021] Chemical reaction formula:

[0022]

[0023] During the reaction process, the conjugated π-electron system of polyaniline can promote electron transfer, accelerate the adsorption and reduction reaction of NO, and confirm the complexation adsorption process of carboxyl (-COOH) and NO in the composition by in-situ infrared spectroscopy (FTIR).

[0024] The denitrification agent composition provided in this example can decompose and reduce NO to generate N2, because the heteropolyacid accelerates the catalysis of nitric oxide to generate azide, and the azide reaction rate is extremely fast, generating N2, H2O, and CO2.

[0025] Specific experimental data table of using the denitrification agent composition provided in this example for boiler combustion flue gas treatment:

[0026] From the data and engineering verification in multiple industries, it is known that by cooperating the denitrification agent composition with related equipment, it can adapt to the denitrification process of low-temperature flue gas and meet the process requirements, achieving denitrification efficiency improvement and environmental protection emission compliance.

[0027] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and the novel concept, makes equivalent replacements or changes, and should be covered within the protection scope of the present invention.

Claims

1. A denitrification agent composition, characterized in that: The invention comprises the following components in weight percentage: 5%-20% of organic acid, 3%-10% of inorganic acid, 0.5%-5% of surfactant, 1%-8% of polyaniline compound, 2% of manganese sulfate, and the balance is water or dimethylformamide.

2. The denitrification agent composition according to claim 1, characterized in that The organic acid is formic acid or acetic acid, the inorganic acid is sulfuric acid, the surfactant is AEO or AES, and the polyaniline compound includes polyaniline or a derivative.

3. A method for preparing the denitrification agent composition according to claim 1, characterized in that: The following steps are involved: S1: Mix the organic acid and the inorganic acid and stir at 40°C-60°C; S2: adding surfactant and polyaniline derivatives, and continuing stirring at a speed of 200-500 rpm for 1-2 hours; S3: Add manganese sulfate, adjust the pH to 3-4, and induce the formation of a stable composite solution through electrochemical doping.

4. The method for preparing the denitrification agent composition according to claim 3, characterized in that: The denitrification agent composition forms a heteropolyacid polynuclear complex by connecting an organic acid, an inorganic acid and a manganese ion through an oxygen bridge, and the manganese ion changes from a low valence state of +2 to a high valence state of +3 or +4.

5. An application of the denitrification agent composition as claimed in claim 1, characterized in that: The denitrification agent composition is used for catalytic reduction of NO in flue gas during the start-stop peak regulation of a 25°C-90°C low-temperature boiler.

6. The use of the denitrification agent composition according to claim 5, characterized in that: The application method is as follows: S1: spraying the denitrification agent composition into the flue through an atomizing nozzle at a pressure of 0.3-0.5 MPa, and controlling the atomized particle size to be ≤50 μm; S2: Adjust the flue gas velocity to 5-15 m / s, the baffle spacing to 1 / 5-1 / 3 mm, the reaction temperature to 25℃-90℃, and the reaction time to 0.5-2 seconds; S3: NO is complexed, adsorbed and reduced to N2, H2O and CO2 through the synergistic effect of heteropolyacid and polyaniline; S4: The PID algorithm is used to dynamically adjust the denitrification agent injection amount to ensure that the denitrification efficiency is maintained above 85% when the flue gas flow fluctuates by ±20%.

7. The use of the denitrification agent composition according to claim 5, characterized in that: An anti-corrosion coating PTFE is arranged in the flue to resist acid corrosion of heteropolyacid.

8. The use of the denitrification agent composition according to claim 5, characterized in that: The conjugated π-electron system of polyaniline can promote electron transfer and accelerate the adsorption and reduction reaction of NO.

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