A method of using a synergist for denitration of an SNCR system

Abstract

This application discloses a method for using a synergistic enhancer in SNCR system denitrification, relating to the field of flue gas denitrification technology. The method includes the following steps: S1, preparation of the synergist composition: including potassium acetate, sodium carbonate, and water, the above raw materials are placed in a synergist preparation tank and stirred to prepare a synergist solution; S2, ammonia water delivery: the ammonia water solution is delivered through an ammonia water delivery pipeline; S3, delivery and mixing of the synergist solution for denitrification: the synergist solution is delivered to the ammonia water delivery pipeline through a synergist delivery device, so that the synergist solution and the ammonia water solution are mixed to obtain a mixed solution, which is then sprayed into the incinerator furnace for denitrification reaction. This application uses potassium acetate and sodium carbonate in a specific ratio to form a denitrification enhancer, which has a simpler structure, is easier to prepare, and requires a lower synergist dosage, effectively reducing the raw material and preparation costs of denitrification operations in incinerators, and significantly improving denitrification efficiency and reducing NOx emissions.

Description

Technical Field

[0001] This application relates to the technical field of flue gas denitrification treatment, and in particular to a method for using a synergistic agent in an SNCR system for denitrification. Background Technology

[0002] Currently, SNCR (Selective Non-Catalytic Reduction) is a catalyst-free flue gas denitrification process. Its core principle involves injecting ammonia or urea solution into the flue gas as a reducing agent within a specific temperature range of 850-1100℃. Through a chemical reaction, nitrogen oxides (NOx) are reduced to nitrogen (N2) and water vapor (H2O). This technology is characterized by low investment costs in industrial applications due to its catalyst-free nature and simple system structure. However, strict temperature control is necessary to ensure effective denitrification, with denitrification efficiency typically between 30% and 60%. Only about half of the ammonia nitrogen in the ammonia solution entering the furnace system reacts with NO. In the SNCR process, adding specific concentrations of potassium, sodium, or acetate salts as additives to the reducing agent (ammonia solution) can significantly optimize the reaction activity, increasing NOx removal efficiency to a higher level of 66%-72%, thus achieving more efficient flue gas denitrification.

[0003] In related technologies, the invention patent document with publication number CN120789888A provides an SNCR denitrification enhancer, a denitrification composition, and a denitrification method. This denitrification enhancer comprises an organic solvent and an alkali metal carboxylate, with a mass ratio of organic solvent to alkali metal carboxylate of (0.1–1):1. The organic solvent is one or more selected from alcohols, ketones, ethers, and aldehydes, and the alkali metal carboxylate is at least one selected from alkali metal formate, acetate, citrate, oxalate, ascorbate, and tartrate. This technology uses a complex enhancer, requires a large dosage, and has not verified the emission reduction effect of SNCR across the entire temperature reaction range in a production facility.

[0004] Meanwhile, the invention patent document with authorization announcement number CN111715050B also provides a method for improving the denitrification efficiency of urea using an alkaline alcohol solution. This synergist is composed of the following raw materials in parts by weight: 90-98 parts ethanol; 2-10 parts strong alkali. The strong alkali is sodium hydroxide, potassium hydroxide, or a mixture thereof. The volume ratio of the denitrification synergist to the urea solution is 5-15:100. This technology suffers from limited potential for improving denitrification efficiency. Summary of the Invention

[0005] The purpose of this application is to provide a method for using a synergistic enhancer in SNCR system denitrification, in order to solve the problems of existing synergists being complex, requiring large dosages, not verifying the emission reduction effect of SNCR across the entire temperature reaction range in a production setting, and having limited room for improvement in denitrification efficiency.

[0006] The technical solution provided in this application for a method of using a synergistic enhancer in an SNCR system for denitrification is as follows: A method for using a synergistic enhancer in an SNCR system for denitrification includes the following steps: S1. Raw material components and preparation of the synergist composition: The synergist composition is a mixture of acetate and carbonate solutions. The mixture includes the following raw material components in parts by mass: 60-80 parts potassium acetate, 20-40 parts sodium carbonate, and 3200-10000 parts water. The above raw materials are sequentially placed into a synergist preparation tank and stirred and mixed to prepare a synergist solution with a mass concentration of 1%-3%. S2. Ammonia water transportation: A 20% ammonia water solution is transported through an ammonia water transportation pipeline; S3. Delivery and mixing of synergist solution for denitrification: The synergist solution prepared in step S1 is delivered to the ammonia water delivery pipeline through the synergist delivery device, so that the synergist solution and the ammonia water solution are mixed to obtain a mixed solution, and the mixed solution is sprayed into the furnace of the incinerator for denitrification reaction.

[0007] Further, in step S1, the mass concentration of the synergist solution is 2%.

[0008] Further, in step S3, the volume ratio of the synergist solution to the ammonia solution is 5~10:100.

[0009] Furthermore, the temperature of the mixed solution injected into the incinerator furnace is between 1000-1100°C.

[0010] Furthermore, the synergist solution prepared using potassium acetate and sodium carbonate can form a dual buffer system, effectively neutralizing the strongly acidic components in the flue gas and inhibiting sudden drops in local pH; the buffering capacity of the dual buffer system follows the Henderson-Hasselbalch equation: Among them, pKa≈4.76, which enables it to still play an auxiliary role in stabilizing pH under high temperature flue gas conditions.

[0011] Furthermore, the high-temperature environment of the flue gas is 700-950℃. Under the high-temperature environment of the flue gas at 700-950℃, the synergist solution forms a low-melting-point potassium acetate-sodium carbonate eutectic mixture, and the melting point of the eutectic mixture is 550-650℃.

[0012] Furthermore, the synergist delivery device is disposed between the synergist preparation tank and the ammonia water delivery pipeline. The synergist delivery device includes a synergist delivery pipeline with one end connected to the output end of the synergist preparation tank and the other end connected to the ammonia water delivery pipeline. A reagent pump, a synergist pressure gauge and a synergist flow meter are also sequentially disposed on the synergist delivery pipeline.

[0013] Furthermore, an synergist return pipeline is also provided between the synergist delivery pipeline and the synergist preparation tank.

[0014] Furthermore, an ammonia flow meter and an ammonia pressure gauge are sequentially installed on the ammonia water delivery pipeline.

[0015] Furthermore, the incinerator is connected to a mixed liquid input pipeline at its input end, and the input end of the mixed liquid input pipeline is connected to the output end of the ammonia water delivery pipeline. A mixed liquid pressure gauge is also installed on the mixed liquid input pipeline.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: This application proposes a denitrification enhancer composed of potassium acetate and sodium carbonate in a specific ratio. Its structure is simpler, its preparation is more convenient, and the amount of enhancer used is lower. This effectively solves the problems of complex enhancers and large dosage requirements in the prior art, thereby reducing the raw material cost and preparation cost of denitrification operations in incineration plants. Meanwhile, through the synergistic effect of potassium acetate and sodium carbonate, the problem of low denitrification efficiency caused by the effective ammonia nitrogen participating in the reaction during the operation of SNCR technology in incineration plants, which is only about 50%, can be solved. This can significantly improve denitrification efficiency and reduce NOx emission indicators, thereby enabling production to achieve lower nitrogen oxide emission indicators to meet environmental emission requirements. This also makes up for the limited room for improvement in denitrification efficiency in existing technologies. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the SNCR system synergistic denitrification method according to an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the synergist delivery device according to an embodiment of this application.

[0019] Explanation of reference numerals in the attached figures: 1. Synergist preparation tank; 2. Ammonia water delivery pipeline; 21. Ammonia water flow meter; 22. Ammonia water pressure gauge; 3. Synergist delivery device; 31. Synergist delivery pipeline; 32. Agent pump; 33. Synergist pressure gauge; 34. Synergist flow meter; 35. Synergist return pipeline; 4. Incinerator; 41. Mixed liquid input pipeline; 42. Mixed liquid pressure gauge. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0021] This application discloses a method for using a synergistic enhancer in an SNCR system for denitrification, referring to... Figure 1 In this embodiment, the method of use includes the following steps: S1. Raw material components and preparation of the synergist composition: The synergist composition is a mixture of acetate and carbonate solutions, and the mixture comprises the following raw material components in parts by mass: 60-80 parts potassium acetate, 20-40 parts sodium carbonate, and 3200-10000 parts water. The above raw materials are sequentially placed into the synergist preparation tank 1 and stirred to prepare a synergist solution with a mass concentration of 1%-3%. Specifically, in step S1, the potassium acetate and sodium carbonate are in powder form, and the preferred mass concentration of the synergist solution is 2%.

[0022] S2, Ammonia water delivery: A 20% ammonia solution is transported through ammonia delivery pipeline 2.

[0023] S3. Delivery and mixing of synergist solution for denitrification: The synergist solution prepared in step S1 is transported to the ammonia water delivery pipeline 2 through the synergist delivery device 3, so that the synergist solution and the ammonia water solution are mixed to obtain a mixed solution, and the mixed solution is sprayed into the furnace of the incinerator 4 for denitrification reaction.

[0024] Specifically, in step S3, the volume ratio of the synergist solution to the ammonia solution is 5~10:100. When a denitrification reaction is required, a 2% (w / w) synergist solution and a 20% (w / w) ammonia solution are mixed at a volume ratio of 5~10:100 and then injected into the furnace of incinerator 4 to carry out the denitrification reaction. This improves the denitrification efficiency and addresses the current situation in incinerators where the effective ammonia nitrogen participating in the reaction during the operation of SNCR technology with ammonia denitrification agents is only about 50%, resulting in excessively low denitrification efficiency.

[0025] Meanwhile, the temperature of the mixed solution injected into the furnace of incinerator 4 is between 1000-1100℃ to ensure that the denitrification reaction fully covers the optimal reaction temperature range, while avoiding the high-temperature range of side reactions where effective ammonia nitrogen is oxidized.

[0026] Preferably, in this embodiment, the mechanism by which potassium acetate can be used as a synergist to improve denitrification efficiency is as follows: potassium acetate can rapidly pyrolyze in high-temperature flue gas at temperatures >700°C, releasing atomic potassium (K·) or low-oxidation potassium species, which can stabilize the transition state of free radical intermediates such as NH2· and NO·, thereby significantly reducing the activation energy of the main reaction NH3+NO→N2+H2O, and thus increasing the reaction rate constant by about 30-40%.

[0027] Meanwhile, in this embodiment, the mechanism by which sodium carbonate is used as an synergist to improve denitrification efficiency is as follows: Sodium carbonate, as a strong alkaline salt, can neutralize acidic components in flue gas, such as SO2 and HCl, thereby maintaining a local alkaline environment. This expands the effective reaction temperature range of SNCR from the traditional 850-1100℃ to 800-950℃, and can significantly improve NOx reduction efficiency, especially in the low-temperature range. Thus, by adding sodium carbonate, the low-temperature denitrification efficiency can be increased by 15-25%, and the generation of byproducts such as N2O can be inhibited.

[0028] Furthermore, in this embodiment, the mechanism by which a mixture of potassium acetate and sodium carbonate can improve denitrification efficiency is as follows: the synergist solution prepared using potassium acetate and sodium carbonate can form a dual buffer system, effectively neutralizing the strongly acidic components in the flue gas and suppressing sudden local pH drops; and the buffering capacity of this dual buffer system follows the Henderson-Hasselbalch equation. Its pKa is approximately 4.76, which allows it to maintain a stable pH even under high-temperature flue gas conditions. These high-temperature conditions range from 700 to 950°C.

[0029] Specifically, the acetate ion, as the conjugate base of acetic acid, reacts with the carbonate ion (CO3). 2- Together, they form a dual buffer system, effectively neutralizing strong acidic components in flue gas, such as SO2 and HCl, thereby suppressing sudden drops in local pH. Furthermore, this buffering effect maintains the stability of the reducing agent (NH3) in the gas phase, preventing its conversion to NH4 under acidic conditions. + It loses its reducing activity, thereby prolonging the effective reaction window.

[0030] Simultaneously, under the high-temperature environment of flue gas at 700-950℃, this synergist solution can form a low-melting-point potassium acetate-sodium carbonate eutectic mixture, and the melting point of this eutectic mixture is 550-650℃. Specifically, acetate ions and potassium ions (K... +At high temperatures, a low-melting-point potassium acetate-sodium carbonate eutectic mixture with a melting point of approximately 550-650℃ is formed, allowing this liquid phase to coat the surface of fly ash particles, thereby significantly reducing the mass transfer resistance of the gas-solid reaction. Furthermore, the weak polarity and spatial structure of the acetate ion contribute to liquid film stability, enhancing the adsorption density and diffusion rate of NH3 molecules on the particle surface, thus compensating for the low gas-phase reaction efficiency in non-catalytic systems.

[0031] Therefore, the present application proposes a denitrification enhancer composed of potassium acetate and sodium carbonate in a specific ratio. This enhancer has a simpler structure, is easier to prepare, and requires a lower dosage. This effectively solves the problems of complex enhancers and large dosage requirements in the prior art, thereby reducing the raw material and preparation costs of denitrification operations in incineration plants.

[0032] Meanwhile, through the synergistic effect of potassium acetate and sodium carbonate, the problem of low denitrification efficiency caused by the effective ammonia nitrogen participating in the reaction during the operation of SNCR technology in incineration plants, which is only about 50%, can be solved. This can significantly improve denitrification efficiency and reduce NOx emission indicators, thereby enabling production to achieve lower nitrogen oxide emission indicators to meet environmental emission requirements. This also makes up for the limited room for improvement in denitrification efficiency in existing technologies.

[0033] The structure of the synergist delivery device 3 is described in detail below: Specifically, refer to Figure 2 In this embodiment, the synergist delivery device 3 is installed between the synergist preparation tank 1 and the ammonia water delivery pipeline 2 to deliver the synergist solution prepared in the synergist preparation tank 1 to the ammonia water delivery pipeline 2.

[0034] The synergist delivery device 3 includes a synergist delivery pipeline 31, a reagent pump 32, a synergist pressure gauge 33, and a synergist flow meter 34. One end of the synergist delivery pipeline 31 is connected to the output end of the synergist reagent preparation tank 1, and the other end of the synergist delivery pipeline 31 is connected to the outside of the output end of the ammonia water delivery pipeline 2. The reagent pump 32, the synergist pressure gauge 33, and the synergist flow meter 34 are respectively installed sequentially on the outside of the synergist delivery pipeline 31.

[0035] The chemical pump 32 provides power to transport the synergist solution in the synergist preparation tank 1 along the synergist delivery pipeline 31 to the ammonia delivery pipeline 2. The synergist pressure gauge 33 effectively monitors the delivery pressure in the synergist delivery pipeline 31 to ensure sufficient pressure for the safe and smooth delivery of the synergist solution to the ammonia delivery pipeline 2. The synergist flow meter 34 enables real-time monitoring and precise flow control of the synergist solution flow rate in the synergist delivery pipeline 31.

[0036] Preferably, in this embodiment, an synergist return pipeline 35 is also provided between the synergist delivery pipeline 31 and the synergist preparation tank 1; after the denitrification operation is completed, under the action of the agent pump 32, the remaining synergist solution in the synergist delivery pipeline 31 can be returned to the agent preparation tank along the synergist return pipeline 35. In this way, the synergist return pipeline 35 is provided to adjust the synergist outlet flow rate and pressure to the required value, or to stop the use of synergist in case of emergency.

[0037] At the same time, refer to Figure 2 In this embodiment, an ammonia storage tank and a delivery pump are installed at the end of the ammonia delivery pipeline 2 away from the synergist delivery pipeline 31. The ammonia storage tank stores an ammonia solution, and the delivery pump delivers the ammonia solution into the ammonia delivery pipeline 2, so that the ammonia solution and the synergist solution mix at the output end of the ammonia delivery pipeline 2.

[0038] Furthermore, an ammonia flow meter 21 and an ammonia pressure gauge 22 are installed sequentially on the ammonia water delivery pipeline 2. The ammonia flow meter 21 enables real-time monitoring and precise control of the ammonia solution flow rate in the ammonia water delivery pipeline 2. The ammonia pressure gauge 22 enables effective monitoring of the delivery pressure in the ammonia water delivery pipeline 2, ensuring sufficient pressure for safe and smooth delivery of the ammonia solution.

[0039] Additionally, refer to Figure 2 In this embodiment, a mixed liquid input pipe 41 is connected to the input end of the incinerator 4. The input end of the mixed liquid input pipe 41 is connected to the output end of the ammonia water conveying pipe 2. Compressed air is also introduced at the connection end between the mixed liquid input pipe 41 and the ammonia water conveying pipe 2. In this way, the mixed liquid input pipe 41 allows the ammonia water solution and the synergist solution to mix in the ammonia water conveying pipe 2 and then be discharged into the mixed liquid input pipe 41. Finally, the mixed solution is sprayed into the furnace of the incinerator 4 for denitrification reaction.

[0040] Furthermore, a mixture pressure gauge 42 is installed on the mixture inlet pipeline 41. The mixture pressure gauge 42 can effectively monitor the delivery pressure in the ammonia water delivery pipeline 2 to ensure that there is sufficient pressure to safely and smoothly deliver the mixture solution into the incinerator 4.

[0041] Example 1: Referring to Table 1 below, taking a 500-ton / day incinerator as an example, the load was controlled to fluctuate between 57-62 t / h during the test, and the ammonia water usage was around 50 L / h.

[0042] As can be seen from Table 1 above, in the above Example 1, after adding a specific combination of synergists, the denitrification efficiency can reach 66-71%, the NOx index can be reduced by 10-22%, and the denitrification efficiency can be increased by about 10-15%.

[0043] Example 2: Referring to Table 2 below, this example still uses a 500-ton / day incinerator. During the test, the load was controlled to fluctuate between 57-62 t / h, and the ammonia water usage was around 50 L / h.

[0044] As can be seen from Table 2 above, in the above Example 2, using potassium acetate alone as a synergist can reduce the NOx index by 2-8% and improve the denitrification efficiency by 2-5%.

[0045] Example 3: Referring to Table 3 below, this example still uses a 500-ton / day incinerator. During the test, the load was controlled to fluctuate between 57-62 t / h, and the ammonia water usage was around 50 L / h.

[0046] As can be seen from Table 3 above, in the above Example 3, using sodium carbonate alone as a synergist can reduce the NOx index by 4-10% and improve the denitrification efficiency by 3-6%.

[0047] Example 4: Referring to Table 4 below, in this example, a 500-ton / day incinerator is still used as an example. During the test, the load is controlled to fluctuate between 57-62 t / h, and the ammonia water usage is about 50 L / h.

[0048] As can be seen from Table 4 above, in the above Example 4, when the addition ratio of the mixture synergist is adjusted, the NOx index can be reduced by 23-28%, and the denitrification efficiency can be increased by 12-15%.

[0049] In summary, although adding sodium carbonate or potassium acetate alone can improve denitrification efficiency to varying degrees in the four embodiments described above, the combined use of the two reagents can achieve a synergistic effect greater than the sum of its parts due to the interaction mechanism between them. Therefore, the present application proposes a method that involves mixing 60-80 parts of potassium acetate, 20-40 parts of sodium carbonate, and water to prepare a 2% (w / w) synergist solution. This solution is then mixed with a 20% (w / w) ammonia solution at a volume ratio of 5-10:100 and injected into the incinerator furnace for denitrification reaction. This can reduce NOx levels by 10-28% and improve denitrification efficiency by approximately 10-15%.

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for using a synergistic agent in an SNCR system for denitrification, characterized in that: Includes the following steps: S1. Raw material components and preparation of the synergist composition: The synergist composition is a mixture of acetate and carbonate solutions. The mixture includes the following raw material components by mass: 60-80 parts of potassium acetate, 20-40 parts of sodium carbonate and 3200-10000 parts of water. The above raw materials are put into the synergist preparation tank (1) in sequence and stirred to prepare a synergist solution with a mass concentration of 1%-3%. S2, Ammonia water transportation: Ammonia water solution with a mass fraction of 20% is transported through ammonia water transportation pipeline (2); S3. Delivery and mixing of synergist solution for denitrification: The synergist solution prepared in step S1 is delivered to the ammonia water delivery pipeline (2) through the synergist delivery device (3) so that the synergist solution and the ammonia water solution are mixed to obtain a mixed solution, and the mixed solution is sprayed into the furnace of the incinerator (4) for denitrification reaction.

2. The method of using a synergistic agent for denitrification in an SNCR system according to claim 1, characterized in that: In step S1, the mass concentration of the synergist solution is 2%.

3. The method of using a synergistic agent for denitrification in an SNCR system according to claim 1, characterized in that: In step S3, the volume ratio of the synergist solution to the ammonia solution is 5~10:

100.

4. The method of using a synergistic agent for denitrification in an SNCR system according to claim 3, characterized in that: The temperature of the mixed solution injected into the furnace of the incinerator (4) is between 1000-1100℃.

5. The method of using a synergistic agent for denitrification in an SNCR system according to claim 1, characterized in that: A synergist solution prepared using potassium acetate and sodium carbonate can form a dual buffer system, effectively neutralizing strongly acidic components in flue gas and inhibiting sudden drops in local pH; the buffering capacity of the dual buffer system follows the Henderson-Hasselbalch equation. Among them, pKa≈4.76, which enables it to still play an auxiliary role in stabilizing pH under high temperature flue gas conditions.

6. The method of using a synergistic agent for denitrification in an SNCR system according to claim 5, characterized in that: The high-temperature environment of the flue gas is 700-950℃. Under the high-temperature environment of the flue gas at 700-950℃, the synergist solution forms a low-melting-point potassium acetate-sodium carbonate eutectic mixture, and the melting point of the eutectic mixture is 550-650℃.

7. The method of using a synergistic agent for denitrification in an SNCR system according to claim 1, characterized in that: The synergist delivery device (3) is located between the synergist preparation tank (1) and the ammonia water delivery pipeline (2). The synergist delivery device (3) includes a synergist delivery pipeline (31) with one end connected to the output end of the synergist preparation tank (1) and the other end connected to the ammonia water delivery pipeline (2). The synergist delivery pipeline (31) is also equipped with a drug pump (32), a synergist pressure gauge (33), and a synergist flow meter (34) in sequence.

8. The method of using a synergistic agent for denitrification in an SNCR system according to claim 7, characterized in that: An synergist return pipeline (35) is also provided between the synergist delivery pipeline (31) and the synergist preparation tank (1).

9. The method of using a synergistic agent for denitrification in an SNCR system according to claim 7, characterized in that: The ammonia water delivery pipeline (2) is also equipped with an ammonia water flow meter (21) and an ammonia water pressure gauge (22) in sequence.

10. The method of using a synergistic agent for denitrification in an SNCR system according to claim 1, characterized in that: The incinerator (4) is connected to a mixed liquid input pipeline (41) at its input end. The input end of the mixed liquid input pipeline (41) is connected to the output end of the ammonia water conveying pipeline (2). A mixed liquid pressure gauge (42) is also installed on the mixed liquid input pipeline (41).

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