A promoting denitration agent used in flue and its denitration process

Abstract

The present application relates to a kind of for flue in promoting denitrification agent and its denitration process, denitrification agent is water or the water solution of reinforcing agent, reinforcing agent is one or several of polyethylene glycol, quaternary ammonium salt, quaternary phosphonium salt, cyclodextrin, tertiary amine etc., is sprayed in flue upstream ozone injection point, denitrification agent is water or the water solution of reinforcing agent, reinforcing agent is one or several of polyethylene glycol, quaternary ammonium salt, quaternary phosphonium salt, cyclodextrin, tertiary amine etc., is sprayed in flue upstream ozone injection point.Compared with traditional O3+CFB semi-dry method absorption denitration technology, water is sprayed in flue to realize the NO x Concentration drop;Reinforcing agent is sprayed in flue to realize the NO x Concentration drop significantly.The present application promotes nitrogen oxides in flue inside CFB absorption tower import, i.e.it realizes the initial concentration reduction of import nitrogen oxides, and in flue by synergistic effect, promote subsequent CFB semi-dry method overall absorption denitration effect, more important is, the present application makes that absorption system antioxidant capacity is enhanced, ensures denitration effect and system stability.

Description

Technical Field

[0001] This invention belongs to the field of flue gas pollutant control, and relates to a denitrification agent and its denitrification process for use in flues. Background Technology

[0002] Nitrogen oxides (NOx) emitted from the combustion of fossil fuels x Nitrogen dioxide (NO2) and nitric oxide (NO) are the main contributors to a series of problems, including photochemical smog, ozone pollution, and acid rain, causing enormous damage to the environment (original flue gas NO). x In large-scale coal-fired power plants, NO content is ≥90%. Ammonia selective catalytic reduction (NH3-SCR) technology was used to reduce NO content in flue gas. x This technology achieves ultra-low emissions. However, it is only suitable for flue gas with temperatures between 300 and 400°C. For flue gas from sintering machines, industrial boilers, and glass kilns with temperatures below 180°C, direct use of NH3-SCR is not feasible. Therefore, a flue gas oxidation combined with CFB semi-dry desulfurization and denitrification technology has been industrially applied in these industries. Oxidants such as O3 oxidize as much of the difficult-to-absorb NO in the flue gas as possible into NO2. NO2 and SO2 are then absorbed through a semi-dry process to achieve simultaneous desulfurization and denitrification. This technology has already achieved a certain scale of industrial application, and it is simple, requires little space, has low investment, produces no waste liquid, and produces no wet flue gas, showing good development prospects.

[0003] However, in traditional flue gas oxidation combined with semi-dry desulfurization and denitrification processes, SO2 is absorbed relatively well, but NO2 is still difficult to absorb. Most projects struggle to achieve ultra-low emissions of nitrogen oxides and are often accompanied by yellow or even red smoke emissions (NO2 coloration). There is an urgent need to find new methods to effectively control nitrogen oxide emissions using existing equipment.

[0004] In existing O3+ circulating fluidized bed (CFB) semi-dry systems, the NO2 absorption reaction primarily occurs in the CFB semi-dry absorption tower, where calcium hydroxide, calcium sulfite, or other reducing agents within the tower neutralize or reduce NO2. -It is important to note that the above reaction relies on NO2 entering the liquid film at the phase interface to complete. However, because the absorbent (solid) added to the absorption tower forms a three-phase mixture zone with the flue gas (gas) and the water (liquid) injected into the tower, the limited reactor size and the space occupied by the solid reduce the degree to which NO2 enters the liquid film, thus inhibiting NO2 removal. Even adding a large excess of calcium hydroxide for NO2 absorption has minimal effect. Therefore, improving the degree to which NO2 enters the liquid film, and thus enhancing the NO2 removal efficiency, is crucial for ensuring ultra-low nitrogen oxide emissions without yellow smoke, and is a problem urgently needing to be solved in this field. In addition, because O3 has strong oxidizing properties, it can easily cause the reducing substances that absorb NO2 to be oxidized, thereby reducing the NO2 absorption capacity. For example, if the amount of O3 used in engineering is increased in order to reduce the NO at the outlet, the large amount of ozone will cause the sulfite (which has reducing properties and can absorb NO2) to be oxidized, which will reduce its NO2 absorption capacity, increase the NO2 at the outlet, and ultimately the total nitrogen oxides at the outlet will still exceed the standard. Therefore, how to improve the oxidation resistance of the denitrification process is also an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a denitrification agent and its denitrification process for flues. Compared with the traditional O3+CFB semi-dry desulfurization and denitrification technology, this invention can achieve higher NO2 absorption and removal efficiency. Furthermore, this invention enhances the antioxidant capacity of the absorption system, further ensuring the stability of the denitrification system.

[0006] The technical solution to achieve the purpose of this invention is: a denitrification agent for use in flues, wherein the denitrification agent is 100% water.

[0007] A denitrification agent for use in flues, the denitrification agent being an aqueous solution of a phase transfer agent, comprising, by mass percentage, one or more of the following components:

[0008]

[0009] Preferably, the relative molecular weight of polyethylene glycol is ≤8000 g / mol.

[0010] Preferably, the quaternary ammonium salt is tetrabutylammonium hydrogen sulfate or tetrabutylammonium chloride.

[0011] Preferably, the cyclodextrin is β- or γ-cyclodextrin.

[0012] Preferred quaternary phosphate salt is pentaerythritol.

[0013] Preferably, the tertiary amine is dodecyl dimethyl benzyl ammonium chloride.

[0014] This invention also provides a denitrification process using an O3+CFB semi-dry system, comprising the following main steps:

[0015] The above-mentioned denitrification agent is atomized and sprayed into the flue of the flue gas to be treated, ensuring that the denitrification agent and the flue gas to be treated are completely mixed before the ozone injection point;

[0016] The thoroughly mixed flue gas and denitrification agent are treated with ozone oxidation by an ozone generator before entering the CFB semi-dry process system. The denitrification agent injection rate is controlled at 0.5–8 t / h. When the denitrification agent is water, the ozone dosage is adjusted to achieve an outlet NO content of 15–40 mg / Nm³. 3 Adjust the amount of denitrification agent injected to achieve an outlet NO2 content of 0–10 mg / Nm³. 3 When the denitrification agent is an aqueous solution of an enhancing agent, adjust the ozone dosage to achieve an outlet NO content of 0–15 mg / Nm³. 3 Adjust the amount of denitrifying agent injected to achieve an outlet NO2 content of 0–5 mg / Nm³. 3 .

[0017] Preferably, the denitrification agent is injected at a position 5m or more upstream of the ozone injection point in the flue gas duct to ensure that the denitrification agent and the flue gas to be treated are completely mixed before the ozone injection point.

[0018] Preferably, the temperature of the flue gas entering the flue is controlled to be 110–180°C, and more preferably, the flue gas temperature is 140±5°C.

[0019] Preferably, the temperature of the flue gas after ozone oxidation treatment is controlled to be 65–95°C after entering the CFB semi-dry process system.

[0020] Preferably, the nitrogen oxides (NOx) in the flue gas to be treated (raw flue gas) are... x =150~380mg / Nm 3 SO2 = 600–2200 mg / Nm³ 3 More preferably, the nitrogen oxides (NOx) in the flue gas to be treated (raw flue gas) x =270mg / Nm 3 SO2 = 1450 mg / Nm 3 .

[0021] Preferably, the O3+CFB semi-dry system used should meet the requirement that the NO concentration in the outlet flue gas does not exceed 50 mg / Nm³ when operating without denitrification agents. 3 Or the NO2 concentration in the flue gas at the outlet should not exceed 65 mg / Nm³. 3 .

[0022] The above-mentioned denitrification agent is used for flue gas desulfurization and denitrification in flue gas ducts.

[0023] Compared with the existing O3+CFB semi-dry denitrification technology, the advantages and beneficial effects of this invention are as follows:

[0024] 1. Due to the promoting effect of the denitrification agent in the flue, the removal effect of NO2 is better, the denitrification rate is higher, and yellow smoke is avoided from the chimney.

[0025] 2. Based on the original O3+CFB, this invention can control the NO2 concentration at the absorber outlet (clean flue gas) by adjusting the flow rate of the denitrification agent.

[0026] 3. In the process of achieving NO2 emission reduction, the use of the denitrification agent and denitrification process involved in this invention can avoid the phenomenon of using a large amount of solid absorbent (such as calcium hydroxide injected by CFB semi-dry method) to deliberately and significantly reduce the NO2 concentration at the outlet (clean flue gas), thereby reducing operating costs.

[0027] 4. Since the injected denitrification agent is a dispersed mist droplet, which is a dispersion medium, the reducing substances in it, such as O3 (which can absorb NO2), are weakened (the free radical chain oxidation reaction cannot be continuously passed on). Therefore, the system's antioxidant capacity is enhanced. While increasing ozone to promote the conversion of NO to NO2, it can protect the reducing absorbent substances that can absorb NO2 from oxidation.

[0028] 5. The denitrification agent and denitrification process of the present invention enhance the stability of the system and make it easier to control. It is only necessary to control the water content of the digester (representing the activity of calcium hydroxide) and maintain the alkaline atmosphere of the system.

[0029] 6. Since the structure of the O3+CFB semi-dry reactor and its auxiliary equipment is not changed, only the denitrification agent storage tank and injection components are added, the use of this invention has almost no additional investment cost due to equipment modification. Attached Figure Description

[0030] Figure 1 This is a simplified diagram of the denitrification process layout corresponding to the denitrification agent described in this invention.

[0031] Figure 2 This is the laboratory evaluation device for denitrifying agents described in this invention.

[0032] Figure 1 In the diagram, 1 is the denitrification agent dosing unit, 2 is the ozone generator, 3 is the CFB semi-dry absorption tower, 4 is the denitrification agent injection point, 5 is the ozone injection point, 6 is the digester, 7 is the quicklime silo, 8 is the small inclined chute, 9 is the water tank, 10 is the pump, 11 is the recovery unit, 12 is the ash hopper, 13 is the slag discharger, 14 is the ash silo, 15 is the induced draft fan, and 16 is the chimney. Detailed Implementation

[0033] To better understand this invention, the principles and content of the invention are further illustrated below with reference to embodiments. However, the content of this invention is not limited to the following embodiments; that is, the following implementation examples further illustrate the content of this invention and should not be construed as limiting the invention. Modifications and substitutions made to the methods, steps, or conditions of this invention without departing from the spirit and substance of this invention are all within the scope of this invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0034] The reaction involving the oxidation of NO to NO2 in this invention is: NO + O3 = NO2 + O2; the main absorption reaction involved is 2NO2 + SO3. 2- +2OH - =2NO2 - +SO4 2- +H2O; the chain-like free radical oxidation side reaction involved is macroscopically manifested as O3 oxidizing SO3. 2- Generate SO4 2- .

[0035] The specific technical principle of this invention mainly lies in:

[0036] 1. According to the present invention, after the atomized denitrification agent is injected into the flue before the ozone injection point, since there are only two phases, gas and liquid, SO2 in the gas phase enters the liquid film faster (compared to the gas-liquid-solid three-phase process in the CFB semi-dry absorption tower. That is, in the gas-liquid-solid three-phase mass transfer process, the solid phase occupies a larger space and the gas-liquid phase contact is uneven).

[0037] 2. Subsequently, after ozone oxidation of NO to NO2, before reaching the feeding position of the CFB semi-dry desulfurization tower, since the system still consists of two phases, gas and liquid, NO2 will accelerate its entry into the liquid film under the action of the denitrification agent. At this time, two situations favorable to denitrification occur: (1) Promoting the denitrification process, that is, NO2 enters the liquid film from the gas phase in the same direction as SO2 entering the liquid film, and the concentration driving force is greater (compared to the gas-liquid-solid three phases in the CFB semi-dry reactor, the mass transfer of solid phase reactants to the liquid film in the liquid film is opposite to that of the gas phase to the liquid film, and the concentration driving force is smaller, resulting in poor mass transfer effect and affecting the NO2 absorption reaction in the liquid film). This will accelerate the reaction between dissolved NO2 and dissolved SO2 in the liquid film and reduce the NO2 concentration entering the CFB semi-dry reactor. (2) Antioxidant process: Since the injected denitrification agent is a dispersed mist droplet, which is a dispersion medium, it oxidizes the reducing substances in it (such as dissolved SO2, SO3, etc.) 2-When the absorption capacity of these substances for NO2 weakens (the free radical chain oxidation reaction cannot be continuously passed), the antioxidant capacity of the system is enhanced, protecting the reducing substances that can absorb NO2 and making them less susceptible to oxidation. (3) In the synergistic denitrification process, because NO2 and SO2 enter the liquid film faster in the CFB gas-liquid two-phase state, and this process occurs before the CFB semi-dry absorption tower, NO2 and SO2 enter the liquid film quickly and in advance. After colliding with the solid absorbent in the CFB semi-dry absorption tower, the denitrification reaction is faster, and the denitrification is enhanced synergistically with the CFB semi-dry absorption tower.

[0038] 3. The denitrification agent is an aqueous solution of water or a reinforcing agent, wherein the reinforcing agent is essentially a phase transfer agent, that is, it increases the rate at which NO2 and SO2 enter the liquid film.

[0039] When the denitrification agent is water: After water is injected into the flue, the flue gas temperature (101-180℃) is higher than the vaporization temperature of water, causing the water to continuously evaporate in the flue. During this process, the atomized water droplet size gradually decreases. According to the two-mode theory, the liquid film thickness of the droplets also gradually decreases. Therefore, the resistance encountered by SO2 and NO2 in the process of transferring from the gas phase to the liquid phase through the liquid film decreases, and the gas-liquid mass transfer rate increases. Some SO2 and NO2 are absorbed by the injected atomized water in the flue; in addition, because some SO2 is absorbed by the atomized water in the flue, it dissolves and transforms into water-soluble SO3. 2- Ions, SO3 2- Ions enter the FCB semi-dry reactor with the flue gas, thereby increasing the concentration of reducing substances that can react with NO2 in the absorption tower. Combined with CFB semi-dry denitrification, higher denitrification efficiency is achieved.

[0040] When the denitrification agent is an aqueous solution of an enhancing agent, its core components include polyethylene glycol, quaternary ammonium salts, quaternary phosphate salts, cyclodextrin, and tertiary amines. The aqueous solution of these five substances, within the content range described in this invention, further enhances the removal of NO2. In the absorption denitrification process, the mass transfer process before the gas passes through the liquid film to reach the solution is the rate-determining step in the entire absorption process. The low gas-liquid mass transfer rate of NO2 is the main reason limiting the denitrification efficiency. Therefore, the means to improve denitrification efficiency is to increase the mass transfer rate of NO2. The enhancing agent is essentially a phase transfer agent, which can help SO2 and NO2 reactants transfer from the gas phase to the liquid phase, thereby accelerating the reaction and dissolution rate between the gas and liquid phases. Compared to injecting water into the flue, injecting the enhancing agent into the flue further reduces the gas-liquid mass transfer resistance due to the phase transfer agent as its core component, facilitating the transfer of gas components to the liquid solution. This promotes the transfer of more SO2 and NO2 from the flue gas to the atomized water, meaning more SO2 and NO2 are dissolved and absorbed by the phase transfer agent. Furthermore, more SO2 is absorbed and converted into SO3 in the flue. 2-The addition of ions further increases the concentration of reducing substances that can react with NO2 in the absorption tower. Combined with the CFB semi-dry reactor for denitrification, the denitrification efficiency is further improved.

[0041] Based on this, corresponding denitrification agent injection adjustment and CFB process control are required to maintain the denitrification effect, thereby achieving efficient absorption of nitrogen oxides. It should be noted that the original O3+CFB semi-dry desulfurization and denitrification method needs to have a certain denitrification effect; that is, the O3+CFB semi-dry system used in this invention must meet the requirement that the NO concentration in the outlet flue gas does not exceed 50 mg / Nm³ when operating without any denitrification agent. 3 Or the NO2 concentration in the flue gas at the outlet should not exceed 65 mg / Nm³. 3 The O3+CFB semi-dry system must meet the above conditions for ultra-low nitrogen oxide emissions to be achieved using the denitrification agent of this invention. If the above values ​​are exceeded, it indicates that the original system itself has too low a denitrification effect, and this invention will also be unable to achieve ultra-low nitrogen oxide emissions.

[0042] The denitrification process based on the denitrification agent described in this invention is as follows: Figure 1 The entire treatment process requires a denitrification agent dosing assembly, denitrification agent atomizing spray, O3 injection from the existing denitrification system, and CFB semi-dry absorption tower, digester, quicklime silo, small inclined chute, and recovery assembly from the CFB system. The denitrification agent dosing assembly of this invention is used to hold and periodically add denitrification agent. It only needs to ensure that the added denitrification agent can be sprayed into the flue through the atomizing nozzle; there are no other special requirements. This invention specifically includes the following steps:

[0043] S1, the denitrification agent is atomized and sprayed into the flue through the atomizing nozzle; the injection position of the denitrification agent is 5m or more upstream of the ozone injection point, so as to keep the denitrification agent and flue gas completely mixed before the ozone injection point. Preferably, the injection position of the denitrification agent is 20m upstream of the ozone injection point.

[0044] S2, the completely mixed flue gas and denitrification agent, after ozone oxidation treatment by an ozone generator, enter the CFB semi-dry absorption system. The main operating parameters of this system are: the bed pressure drop of CFB semi-dry absorption tower 3 is 0.6-1.5 kPa, preferably 1.0 kPa; water in water tank 9 is injected into CFB semi-dry absorption tower 3 through a spray gun via pump 10. The temperature of the flue gas entering the CFB semi-dry absorption tower is adjusted by controlling the pump's water spray volume or the amount of denitrification agent injected, ensuring that the flue gas temperature is 65-95℃, preferably when the flue gas flow rate is 1.2 million Nm³. 3At a rate of 3.0 t / h, the injection rate of denitrifying agent is controlled, the water injection rate of the pump in the CFB system is controlled, and the flue gas temperature entering the CFB semi-dry absorption tower is controlled at 80.5℃. Similar to existing technologies, the digester water rate must be controlled at at least 300 L / t. The higher the water rate, the more stable the denitrification effect. The feed rate of the small inclined chute is 1.5 t to 10 t / h (i.e., the amount of calcium hydroxide used, and this amount decreases as the water rate increases during operation).

[0045] S3, the flue gas after the desulfurization and denitrification reaction is discharged from the top of the CFB semi-dry absorption tower 2 and enters the recovery component 11. The dust (containing unreacted absorbent and reaction products) is recovered by the dust collection component 11. The pressure drop of the filter bag in the recovery component is 0.8-1.8 kPa, preferably 1.0 kPa. The purified flue gas (outlet flue gas) is transported to the chimney 16 by the fan 15 and discharged into the atmosphere. The pressure difference of the ash hopper 12 under the recovery component is 5-15 kPa, preferably 9 kPa. The unreacted absorbent and reaction products settle at the bottom of the ash hopper 12. Some of the captured material enters the slag bin 14 through the slag discharger 13. The opening of the slag discharger 13 is controlled to control the amount of material discharged, preventing the large amount of nitrite generated by the absorbent from being reversed to generate NO due to excessive pressure difference.

[0046] S4, based on the existing O3+CFB semi-dry denitrification effect, that is, the NO concentration at the outlet of the original absorption tower (without using the denitrification agent of this invention) is not higher than 50 mg / Nm³. 3 Or the NO2 concentration at the absorber outlet should not exceed 65 mg / Nm³. 3 The denitrification agent injection rate is 0.5–8 t / h; when using water as the denitrification agent: the NO content in the outlet flue gas can be adjusted to 15–40 mg / Nm³ by adjusting the ozone dosage. 3 Adjust the dosage of denitrification agent to achieve an NO2 content of 0–10 mg / Nm³ in the outlet flue gas. 3 When using an enhanced aqueous solution as a denitrification agent: the ozone dosage is adjusted to achieve an NO content of 0–15 mg / Nm³ in the outlet flue gas. 3 Adjust the dosage of denitrification agent to achieve an NO2 content of 0–5 mg / Nm³ in the outlet flue gas. 3 Preferably, when the flue gas flow rate is 1.2 million Nm3 / h, the injection rate of the denitrification agent is 3.0 t / h.

[0047] It should be noted that the temperature of the flue gas to be treated in this invention is 101–180°C. In actual engineering, flue gas conditions below 101°C and above 180°C are almost nonexistent. Furthermore, laboratory testing methods (see attached diagram) are used. Figure 2When evaluating the denitrification performance of the denitrification agent described in this invention, it was found that when the flue gas temperature is below 101°C, the NO2 in the outlet flue gas can be adjusted to 10 mg / Nm³. 3 Below, and with total nitrogen oxides below 50 mg / Nm 3 However, due to the low flue gas temperature, the denitrification agent of this invention forms obvious liquid droplets. In actual engineering, these droplets absorb SO2 and become acidic, corroding the flue. Therefore, the temperature of the flue gas to be treated cannot be lower than 101°C. When the flue gas temperature is higher than 180°C, the amount of ozone used increases significantly, approximately 2.6 times that at 140°C (assuming the same conversion of NO to NO2). This indicates that O3 decomposes more significantly at this temperature, leading to a waste of O3 in practical engineering. Some projects, lacking sufficient ozone generators, cannot guarantee adequate conversion of NO to NO2 at high flue gas temperatures. Therefore, the flue gas temperature treated by the denitrification process using the denitrification agent of this invention is 101–180°C.

[0048] The raw materials used in Examples 1-43 below are industrial grade and contain impurities. These impurities do not react or interact with NO2, NO, or SO2. Furthermore, the following examples, which do not include specific laboratory-condition experiments, are based on data obtained from the O3+CFB semi-dry system. If laboratory-condition denitrification tests are conducted, laboratory conditions refer to a flue gas volume of 0.06–0.3 Nm³. 3 / h, other conditions are shown in Tables 1 and 2, and the operating system is as follows: Figure 2 Unless otherwise specified, the denitrification agents used in Examples 1-43 and the comparative examples are all denitrification agents protected by this invention.

[0049] Example 1

[0050] At a point 20m upstream of the ozone injection point in the flue, a denitrification agent (water) is injected through an atomizing nozzle at a rate of 3.0t / h. The inlet flue gas conditions are shown in Table 1, and the operating conditions are shown in Table 2.

[0051] Example 2

[0052] At a point 20m upstream of the ozone injection point in the flue, a denitrification agent, namely a 5wt% polyethylene glycol aqueous solution, is injected through an atomizing nozzle. The polyethylene glycol used is polyethylene glycol 4000, and the injection rate is 3.0t / h. The inlet flue gas conditions are shown in Table 1, and the operating conditions are shown in Table 2.

[0053] Comparative Example 1

[0054] No denitrification agent was sprayed into the flue.

[0055] Table 1 Inlet Flue Gas Conditions

[0056] Types of exhaust gases <![CDATA[Flue gas volume (Nm 3 / h)]]> <![CDATA[SO2(mg / Nm 3 )]]> <![CDATA[NO x (mg / Nm 3 )]]> Flue gas temperature (°C) Sintering flue gas 1000000～1250000 Around 1450 Around 270 140±5

[0057] Note: Operating time is calculated based on 24 hours / day; Import NO x The volume content of NO is over 95%.

[0058] Table 2 Main Operating Conditions

[0059]

[0060] Note: Adjusting O3 usage involves adjusting the ozone generator power, which in turn adjusts the O3 usage (the amount injected into the flue). The outlet NO concentration in this table fluctuates, with a positive and negative deviation of 2 mg / Nm³. 3 The values ​​listed in the operating conditions are average values.

[0061] Table 3 Comparison of the effects of using and not using denitrification agents.

[0062]

[0063] Note: The import conditions are in Table 1, and the main operating conditions are in Table 2. x Including NO and NO2. Denitrification rate: (imported NO) x -(Export NO2 + Export NO × 46 / 30)) ÷ Import NO x .

[0064] The comparison of the effects of using and not using denitrification agents is shown in Table 3. The O3 usage was adjusted to control the NO concentration at the CFB absorber outlet to 35 mg / Nm³. 3 The NO2 levels in the outlet flue gas were significantly lower than those without the denitrification agent (Comparative Example 1) after using the denitrification agent (Examples 1 and 2), indicating that the denitrification agent promoted the absorption and removal of NO2. Furthermore, the three sets of data in Table 3 show that the NO levels in the outlet flue gas were comparable to those at the inlet, indicating that NO was hardly absorbed. Therefore, in practical engineering, the amount of O3 used should be increased to continuously improve the conversion of NO (difficult to absorb) into absorbable NO2. Only then, through efficient NO2 absorption, can the total nitrogen oxides (NO) at the outlet be reduced. x The goal of ultra-low emissions.

[0065] Table 4 Antioxidant Effect

[0066]

[0067] Note: The inlet conditions in this table are from Table 1. The operating conditions are a reactor top temperature of 80.5℃ and a pressure drop of 1.0 kPa in the absorption tower bed. Adjusting the O3 usage is done by adjusting the ozone generator power, which in turn adjusts the O3 usage (the amount injected into the flue). Increasing the O3 usage decreases the outlet NO concentration, meaning NO is oxidized to NO2 (NO + O3 = NO2 + O2).

[0068] The antioxidant effects of this invention are listed in Table 4. In Examples 1, 2, and Comparative Example 1, the outlet NO concentration decreased continuously with increasing O3 usage, indicating that O3 converted NO to NO2, thus reducing NO levels. However, as the outlet flue gas NO levels in Examples 1, 2, and Comparative Example 1 remained at 35, 15, and 9 mg / Nm³, respectively... 3 At approximately [time missing], without the use of a denitrification agent (Comparative Example 1), the NO2 concentration in the outlet flue gas eventually rose to 61 mg / Nm³. 3 The NO2 concentration at the outlet increased significantly. Under these conditions, the desulfurization and denitrification products (ash discharged from the system) were tested, and the remaining mass content of the reducing substances that can absorb NO2 was less than 3%; while in Examples 1 and 2, the remaining reducing substances were >10%. Confirmation and analysis showed that because the injected denitrification agent was a dispersed mist droplet, it was a dispersion medium, which weakened the oxidation of reducing substances (which can absorb NO2) by O3 and other substances (these substances cannot continuously carry out the free radical chain oxidation reaction). Therefore, the system's antioxidant capacity was enhanced. While increasing ozone to promote the conversion of NO to NO2, it could protect the reducing substances that can absorb NO2 from oxidation.

[0069] Furthermore, with the continuous increase in O3 usage, the NO2 concentration in the flue gas at the outlet of Example 2 was relatively lower than that of Example 1. This phenomenon is related to two possible reasons: (1) the reinforcing agent polyethylene glycol has reducing properties, and its aqueous solution can react with O3, consuming excess O3, thereby enhancing the antioxidant capacity of the absorption system and thus improving NO2 absorption; (2) with the increase of O3, the amount of NO2 generated in the system increases, and the reinforcing agent polyethylene glycol aqueous solution itself has better capabilities, giving the system a higher NO2 absorption capacity.

[0070] Example 3

[0071] Under laboratory conditions, denitrification agent water was sprayed into the flue 5m upstream of the ozone injection point through an atomizing nozzle.

[0072] Example 4

[0073] Under laboratory conditions, denitrification agent water was sprayed into the flue 10m upstream of the ozone injection point through an atomizing nozzle.

[0074] Example 5

[0075] Under laboratory conditions, denitrification agent water was sprayed into the flue 20m upstream of the ozone injection point through an atomizing nozzle.

[0076] Example 6

[0077] Under laboratory conditions, denitrification agent water was sprayed into the flue 30m upstream of the ozone injection point through an atomizing nozzle.

[0078] Example 7

[0079] Under laboratory conditions, denitrification agent water was sprayed into the flue 40m upstream of the ozone injection point through an atomizing nozzle.

[0080] Table 5. Effect of distance between the denitrification agent injection point and the O3 injection point.

[0081]

[0082] Note: Due to the difficulty in engineering practice to drill holes and install atomizing nozzles at precise distances, the experimental data in this table were obtained from laboratory measurements. The laboratory setup process is as follows: Figure 2 As shown in the figure. The inlet flue gas temperature is 140℃, and the inlet flue gas NO concentration is 270 mg / Nm³. 3 (Without additional NO2 added), SO2 concentration is 1450 mg / Nm³. 3 In Example 5, the dosage of O3 and the dosage of denitrification agent were adjusted to achieve engineering-standard equal levels of NO2 and NO in the outlet flue gas (Example 1). The dosage of O3 used in other laboratory examples was the same as in Example 5.

[0083] The effect of the distance between the denitrification agent injection point and the O3 injection point is shown in Table 5. As the distance between the denitrification agent injection point and the O3 injection point increases to 20m, the NO2 content in the outlet flue gas gradually decreases. This is related to the mixing state of the denitrification agent before the O3 injection point; that is, the longer the distance, the better the mixing effect, and the residence time of SO2 in the liquid film is guaranteed, providing conditions for subsequent synergistic effects. After the flue gas reaches the O3 injection point, as O3 reacts with NO to generate NO2, the well-mixed denitrification agent will further react with NO2, promoting denitrification. When the distance between the denitrification agent injection point and the O3 injection point increases to 30m (Example 6), the NO2 and NO content in the outlet flue gas are basically consistent with the data in Example 5 (where the distance between the denitrification agent injection point and the O3 injection point is increased to 20m). Therefore, the denitrification effect can remain stable within a certain range of the distance between the denitrification agent injection point and the O3 injection point. When the distance between the denitrification agent injection point and the O3 injection point increased to 40m (Example 7), the NO2 and NO content in the outlet flue gas increased compared to Examples 5 and 6, while NO remained unchanged. This phenomenon can be attributed to the fact that, with the increase in distance, the injected denitrification agent partially vaporizes under the action of high-temperature flue gas, causing the SO2 ions obtained from the original liquid film to eventually return to the gas phase. This vaporization product cannot play a role in absorbing NO2.

[0084] Example 8

[0085] At a point 20m upstream of the ozone injection point in the flue, denitrification agent water is sprayed through an atomizing nozzle at a rate of 0.5t / h.

[0086] Example 9

[0087] At a point 20m upstream of the ozone injection point in the flue, denitrification agent water is injected through an atomizing nozzle at a rate of 1.5t / h.

[0088] Example 10

[0089] At a point 20m upstream of the ozone injection point in the flue, denitrification agent water is injected through an atomizing nozzle at a rate of 3.0t / h.

[0090] Example 11

[0091] At a point 20m upstream of the ozone injection point in the flue, denitrification agent water is injected through an atomizing nozzle at a rate of 5.0t / h.

[0092] Example 12

[0093] At a point 20m upstream of the ozone injection point in the flue, denitrification agent water is injected through an atomizing nozzle at a rate of 8.0t / h.

[0094] Table 6. Effect of Denitrification Agent Injection Amount

[0095]

[0096] Note: The import conditions in this table are shown in Table 1, the operating conditions are shown in Table 2, and the denitrification agent is water. x Including NO and NO2.

[0097] Table 6 shows the effect of the denitrification agent injection rate. As can be seen from Table 6, when the injection rate is 0.5 t / h, the NO2 content in the outlet flue gas is higher compared to other injection rates; as the injection rate increases to 1.5 t / h, the NO2 content in the outlet flue gas begins to decrease; after further increasing the injection rate (Examples 10, 11, and 12), the NO2 content in the outlet flue gas remains essentially unchanged. Therefore, there is an optimal amount of denitrification agent, and further increasing the injection rate does not change the denitrification effect. However, in practical applications, a larger injection rate will significantly reduce the flue gas temperature, leading to corrosion and water accumulation in the flue, which is detrimental to production and equipment.

[0098] Example 13

[0099] At a point 20m upstream of the ozone injection point in the flue, a 5wt% polyethylene glycol aqueous solution is sprayed into the flue through an atomizing nozzle. The polyethylene glycol is polyethylene glycol 2000, and the injection rate is 3t / h.

[0100] Example 14

[0101] At a point 20m upstream of the ozone injection point in the flue, a polyethylene glycol aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The polyethylene glycol is polyethylene glycol 6000, the concentration of the polyethylene glycol aqueous solution is 5%, and the injection rate is 3t / h.

[0102] Example 15

[0103] At a point 20m upstream of the ozone injection point in the flue, a polyethylene glycol aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The polyethylene glycol is polyethylene glycol 8000, the concentration of the polyethylene glycol aqueous solution is 5%, and the injection rate is 3t / h.

[0104] Example 16

[0105] At a point 20m upstream of the ozone injection point in the flue, a denitrification agent quaternary ammonium salt aqueous solution is sprayed through an atomizing nozzle. The quaternary ammonium salt refers to tetrabutylammonium hydrogen sulfate or tetrabutylammonium chloride. The concentration of the quaternary ammonium salt aqueous solution is 3%, and the injection rate is 3t / h.

[0106] Example 17

[0107] At a point 20m upstream of the ozone injection point in the flue, a denitrification agent quaternary phosphate aqueous solution is sprayed through an atomizing nozzle. The quaternary ammonium salt refers to pentaerythritol, the concentration of the quaternary phosphate aqueous solution is 3%, and the injection rate is 3t / h.

[0108] Example 18

[0109] At a point 20m upstream of the ozone injection point in the flue, an aqueous solution of β-cyclodextrin, a denitrification agent, is sprayed through an atomizing nozzle. The concentration of the β-cyclodextrin aqueous solution is 5%, and the injection rate is 3t / h.

[0110] Example 19

[0111] At a point 20m upstream of the ozone injection point in the flue, an aqueous solution of γ-cyclodextrin, a denitrification agent, is sprayed through an atomizing nozzle. The concentration of the γ-cyclodextrin aqueous solution is 5%, and the injection rate is 3t / h.

[0112] Example 20

[0113] At a point 20m upstream of the ozone injection point in the flue, an aqueous solution of tertiary amine denitrification agent is sprayed through an atomizing nozzle. The tertiary amine is dodecyl dimethyl benzyl ammonium chloride, the concentration of the tertiary amine aqueous solution is 3%, and the injection rate is 3t / h.

[0114] Table 7. Effects of different types of reinforcing agents on denitrification agents

[0115]

[0116] Note: The import conditions for this table are in Table 1, and the operating conditions are in Table 2. NO x Including NO and NO2. Denitrification rate: (imported NO) x -(Export NO2 + Export NO × 46 / 30)) ÷ Import NO x .

[0117] Table 7 shows the effect of different types of reinforcing agents in denitrification agents. As can be seen from Table 7, when the type of reinforcing agent changes, that is, when different polyethylene glycols, as well as quaternary ammonium salts, quaternary phosphate salts, cyclodextrins, and tertiary amine aqueous solutions are used as reinforcing agents, the denitrification effect is almost the same, indicating that all of the above substances can achieve the purpose of denitrification.

[0118] Example 21

[0119] At a point 20m upstream of the ozone injection point in the flue, a polyethylene glycol aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The polyethylene glycol is polyethylene glycol 4000, the concentration of the polyethylene glycol aqueous solution is 3%, and the injection rate is 3.5 tons / h.

[0120] Example 22

[0121] At a point 20m upstream of the ozone injection point in the flue, a polyethylene glycol aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The polyethylene glycol is polyethylene glycol 4000, the concentration of the polyethylene glycol aqueous solution is 10%, and the injection rate is 1.5 tons / h.

[0122] Example 23

[0123] At a point 20m upstream of the ozone injection point in the flue, a quaternary ammonium salt aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the quaternary ammonium salt aqueous solution is 2%, and the injection rate is 3.5 tons / h.

[0124] Example 24

[0125] At a point 20m upstream of the ozone injection point in the flue, a quaternary ammonium salt aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the quaternary ammonium salt aqueous solution is 5%, and the injection rate is 1.5 tons / h.

[0126] Example 25

[0127] At a point 20m upstream of the ozone injection point in the flue, a quaternary phosphate salt aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the quaternary phosphate salt aqueous solution is 2%, and the injection rate is 3.5 tons / h.

[0128] Example 26

[0129] At a point 20m upstream of the ozone injection point in the flue, a quaternary phosphate salt aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the quaternary phosphate salt aqueous solution is 5%, and the injection rate is 1.5 tons / h.

[0130] Example 27

[0131] At a point 20m upstream of the ozone injection point in the flue, an aqueous solution of γ-cyclodextrin, a denitrification agent, is sprayed through an atomizing nozzle. The concentration of the γ-cyclodextrin aqueous solution is 3%, and the injection rate is 3.5 tons / h.

[0132] Example 28

[0133] At a point 20m upstream of the ozone injection point in the flue, an aqueous solution of γ-cyclodextrin, a denitrification agent, is sprayed through an atomizing nozzle. The concentration of the γ-cyclodextrin aqueous solution is 10%, and the injection rate is 1.5 tons / h.

[0134] Example 29

[0135] At a point 20m upstream of the ozone injection point in the flue, a tertiary amine aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the tertiary amine aqueous solution is 2%, and the injection rate is 3.5 tons / h.

[0136] Example 30

[0137] At a point 20m upstream of the ozone injection point in the flue, a tertiary amine aqueous solution of denitrification agent is sprayed through an atomizing nozzle. The concentration of the tertiary amine aqueous solution is 5%, and the injection rate is 1.5 tons / h.

[0138] Table 8. Effect of Enhancer Concentration in Denitrification Agent

[0139]

[0140] Note: The import conditions for this table are in Table 1, and the operating conditions are in Table 2. NO x Including NO and NO2. Denitrification rate: (imported NO) x -(Export NO2 + Export NO × 46 / 30)) ÷ Import NO x .

[0141] Table 8 shows the effect of the enhancer concentration in the denitrification agent. The effect of the enhancer concentration on denitrification was clarified by increasing (decreasing) the concentration and decreasing (increasing) the injection rate. The denitrification results of Examples 1 and 21-30 show that the operation of increasing (decreasing) the enhancer concentration and decreasing (increasing) the injection rate has little effect on the denitrification effect. Therefore, under the condition of ensuring the injection rate, the enhancer concentration within the range covered in Examples 1 and 21-30 will not affect the denitrification effect.

[0142] Example 31

[0143] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, denitrification agent water was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) was 150 mg / Nm³. 3 The SO2 concentration is 600 mg / Nm³. 3 .

[0144] Example 32

[0145] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, denitrification agent water was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) was 150 mg / Nm³.3 The SO2 concentration was 2200 mg / Nm³. 3 .

[0146] Example 33

[0147] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, denitrification agent water was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) was 380 mg / Nm³. 3 The SO2 concentration is 600 mg / Nm³. 3 .

[0148] Example 34

[0149] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, denitrification agent water was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) was 380 mg / Nm³. 3 The SO2 concentration was 2200 mg / Nm³. 3 .

[0150] Comparative Example 2

[0151] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas, without the use of denitrification agents, the nitrogen oxide (NO) concentration in the flue gas to be treated (raw flue gas) is 380 mg / Nm³. 3 The SO2 concentration is 600 mg / Nm³. 3 .

[0152] Comparative Example 3

[0153] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas, without the use of denitrification agents, the nitrogen oxide (NO) concentration in the flue gas to be treated (raw flue gas) is 150 mg / Nm³. 3 The SO2 concentration was 2200 mg / Nm³. 3 .

[0154] Table 9. Effects of NO and SO2 concentrations in inlet flue gas on the denitrification efficiency of the denitrification agent.

[0155]

[0156] Note: Due to the difficulty in engineering experiments to determine high and low concentrations of NO and SO2 in inlet flue gas, the experimental data in this table are from laboratory equipment. Figure 2 The laboratory apparatus flow was measured as follows: Figure 2 As shown, the NO content in the outlet flue gas was adjusted to 35 mg / Nm³ by adjusting the O3 injection rate. 3 .

[0157] Table 9 shows the effects of inlet flue gas NO and SO2 concentrations on the denitrification effect of the denitrification agent. Example 31 shows that when the inlet flue gas NO concentration is low, even with a low inlet flue gas SO2 concentration, the outlet flue gas NO2 content can still be achieved at 10 mg / Nm³. 3 The following example, Example 32, shows that when the SO2 concentration in the inlet flue gas increases, the NO2 concentration in the outlet flue gas can be lower compared to Example 31. Example 33 shows that when the NO concentration in the inlet flue gas increases to 380 mg / Nm³, 3 When the SO2 concentration in the inlet flue gas is low, the NO2 concentration in the outlet flue gas increases significantly, reaching 41 mg / Nm³. 3 Example 34 shows that, similarly, when the NO concentration in the inlet flue gas was 380 mg / Nm³, 3 Under these conditions, the SO2 concentration in the imported flue gas increased to 2200 mg / Nm³. 3 At the same time, the NO2 concentration at the outlet can still be controlled at a low level. The above results indicate that the SO2 concentration in the inlet flue gas plays a certain role in the denitrification effect. Specifically, when the SO2 concentration in the inlet flue gas is at a reasonable value, more reducing sulfite ions are generated from the absorbed SO2, which can react with NO2 to remove NO2. Therefore, when the NO concentration in the inlet flue gas increases, the SO2 concentration also needs to increase further to ensure that after NO is converted to NO2, the reducing substances can further absorb and remove NO2. Comparative Example 2 shows that when the inlet flue gas NO is high, SO2 is low, and no denitrification agent is used, the NO2 concentration in the outlet flue gas reaches a high 79 mg / Nm³. 3 The increase was significant compared to Example 33, indicating that the denitrification agent played a role in the denitrification process. Analysis of the solid products from Examples 31-34 and Comparative Example 2 showed that examples or comparative examples with higher outlet flue gas NO2 concentrations had lower sulfite content in their solid products, while examples with lower NO2 concentrations had higher sulfite concentrations. Therefore, this conclusion also corroborates the role of the inlet flue gas SO2 concentration and the denitrification agent in denitrification. Comparative Example 3 showed that without the use of a denitrification agent, when the inlet flue gas NO concentration was as low as 150 mg / Nm³, the denitrification agent significantly increased the NO2 concentration. 3 SO2 levels as high as 2200 mg / Nm³ 3 At the same time, it can also achieve good NO2 absorption, indicating that when the flue gas inlet conditions meet the requirements of low NO and high SO2, the system itself has a good denitrification effect.

[0158] Comparative Example 4

[0159] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas, without the use of denitrification agents, the nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) is 270 mg / Nm³. 3 The SO2 concentration was 1450 mg / Nm³.3 Adjust the O3 usage to achieve an outlet NO concentration of 50 mg / Nm³. 3 .

[0160] Comparative Example 5

[0161] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas, without the use of denitrification agents, the nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) is 270 mg / Nm³. 3 The SO2 concentration was 1450 mg / Nm³. 3 Adjust the O3 usage to achieve an outlet NO2 concentration of 65 mg / Nm³. 3 .

[0162] Comparative Example 6

[0163] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas, without the use of denitrification agents, the nitrogen oxide (NO) content in the flue gas to be treated (raw flue gas) is 270 mg / Nm³. 3 The SO2 concentration was 1450 mg / Nm³. 3 Adjust the O3 usage to achieve an outlet NO2 concentration of 66 mg / Nm³. 3 .

[0164] Example 35

[0165] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, an aqueous solution of polyethylene glycol (PEG) was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (original flue gas) was 270 mg / Nm³. 3 The SO2 concentration was 1450 mg / Nm³. 3 The amount of O3 used was the same as in Comparative Example 4.

[0166] Example 36

[0167] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, an aqueous solution of polyethylene glycol (PEG) was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (original flue gas) was 270 mg / Nm³. 3 The SO2 concentration was 1450 mg / Nm³. 3 The amount of O3 used was the same as in Comparative Example 5.

[0168] Example 37

[0169] Under laboratory conditions, at a point 20m upstream of the ozone injection point in the flue gas duct, an aqueous solution of polyethylene glycol (PEG) was sprayed through an atomizing nozzle. The nitrogen oxide (NO) content in the flue gas to be treated (original flue gas) was 270 mg / Nm³. 3The SO2 concentration was 1450 mg / Nm³. 3 The amount of O3 used was the same as in Comparative Example 6.

[0170] Table 10 Relationship between the applicability of denitrification agents and the upper limit of NO and NO2 concentrations in inlet flue gas

[0171]

[0172] Note: Due to engineering limitations, it is difficult to specify the exact amounts of NO and NO2 at the outlet, especially when they exceed 50 mg / Nm³. 3 This would lead to failure to meet ultra-low emission standards. Therefore, the experiment needs to be conducted under laboratory conditions. The experimental data in this table are from laboratory equipment. Figure 2 The laboratory apparatus flow was measured as follows: Figure 2 As shown.

[0173] Table 10 shows the relationship between the applicability of denitrification agents and the upper limits of NO and NO2 concentrations in inlet flue gas. Without using denitrification agents, adjust the O3 dosage until the outlet NO concentration is 50 mg / Nm³. 3 At this point (Comparative Example 4), the amount of O3 used was relatively small, and NO did not convert to NO2 at a high conversion rate. Using the same amount of O3, with other conditions unchanged, after using the denitrification agent (Example 35), NO2 was significantly removed compared to Comparative Example 3, but NO was not removed. This phenomenon is related to the low solubility of NO, which prevents it from being absorbed and removed. This phenomenon also indicates that when the NO concentration in the inlet flue gas exceeds 50 mg / Nm³... 3 Even with denitrification agents, ultra-low emissions of nitrogen oxides (NOx) cannot be achieved. x Emissions below 50 mg / Nm 3 ).

[0174] Comparative Example 5 shows that, based on Comparative Example 4, further increasing the amount of O3 used increased the NO2 content in the flue gas to 65 mg / Nm³. 3 At this point, the NO content in the exhaust gas decreased to 3 mg / Nm³. 3 Using the same amount of O3 and other conditions remaining unchanged, after using the denitrification agent (Example 36), the NO2 content in the outlet flue gas was 10 mg / Nm³. 3 .

[0175] Comparative Example 6 shows that, based on Comparative Example 5, further increasing the amount of O3 used increased the NO2 content in the flue gas to 66 mg / Nm³. 3 At this point, the NO content in the exhaust gas decreased to 2 mg / Nm³. 3 Using the same amount of O3 and other conditions remaining unchanged, after using the denitrification agent (Example 37), the NO2 content in the outlet flue gas was 11 mg / Nm³. 3Although the total nitrogen oxides meet the ultra-low emission limits, this patent requires that the NO2 content at the outlet be maintained at 10 mg / Nm³ after using the denitrification agent. 3 Therefore, the NO2 content in the outlet flue gas exceeds 65 mg / Nm³ without the use of a denitrification agent. 3 Even with the use of denitrification agents, it cannot be guaranteed that the NO2 content in the flue gas will be lower than 10 mg / Nm³. 3 This phenomenon is related to the upper limit of the NO2 release effect of the denitrification agent.

[0176] The denitrification agent formulations for Examples 38-43 are listed in Table 11. Examples 38-43 used different proportions of reinforcing agents to form combined reinforcing agents. Table 12 shows the denitrification effects of the combined reinforcing agents in the corresponding examples.

[0177] Table 11 Denitrification agent formulations for Examples 38-43

[0178]

[0179] Note: All percentages are parts by weight. Example 37 is used as an example: its composition is 60% by weight of polyethylene glycol aqueous solution (concentration of 5%) + 40% by weight of quaternary ammonium salt aqueous solution (concentration of 3%).

[0180] Table 12 Denitrification effect of Examples 38-43

[0181]

[0182]

[0183] Note: The import conditions for this table are in Table 1, and the operating conditions are in Table 2. NO x Including NO and NO2. Denitrification rate: (imported NO) x -(Export NO2 + Export NO × 46 / 30)) ÷ Import NO x .

[0184] As can be seen from Table 12, the denitrification effects of each embodiment are almost the same. Therefore, after mixing different reinforcing agents to form a reinforcing agent, it still has the ability to denitrify.

[0185] In summary, this invention promotes the reduction of nitrogen oxides at the inlet of the CFB absorption tower within the flue, thereby reducing the initial concentration of nitrogen oxides at the inlet. Furthermore, through synergistic effects within the flue, it enhances the overall denitrification effect of the subsequent CFB semi-dry absorption process. More importantly, this invention strengthens the antioxidant capacity of the absorption system, ensuring denitrification efficiency and system stability.

Claims

1. A method for denitration, characterized by, The O3+CFB semi-dry system includes the following main steps: The denitration agent is atomized and sprayed into the flue of the flue gas to be treated to ensure that the denitration agent is completely mixed with the flue gas to be treated before the ozone injection point. The mixed complete flue gas to be treated and the denitration agent are oxidized by the ozone generated by the ozone generator, and then enter the CFB semi-dry system, the injection amount of the denitration agent is controlled to be 0.5-8 t / h, the ozone amount is adjusted so that the outlet NO content is 0-15 mg / Nm 3 , the injection amount of the denitration agent is adjusted so that the outlet NO2 content is 0-5 mg / Nm 3 . The denitration agent is an aqueous solution of a phase transfer agent, and is selected from one or more of the following components in terms of mass concentration: Polyethylene glycol 3~10% Quaternary ammonium salt 2~5% Quaternary phosphonium salt 2~5% Cyclodextrin 3~10% Tertiary amine 2~5%; The cyclodextrin is β-type or γ-type cyclodextrin. The tertiary amine is dodecyl dimethyl benzyl ammonium chloride.

2. The method of claim 1, wherein, The relative molecular weight of the polyethylene glycol is ≤8000 g / mol.

3. The method of claim 1, wherein, The quaternary ammonium salt is tetrabutylammonium hydrogen sulfate or tetrabutylammonium chloride.

4. The method of claim 1, wherein, The denitration agent is sprayed at a position 5 m or more upstream of the ozone injection point in the flue to ensure that the denitration agent is completely mixed with the flue gas to be treated before the ozone injection point.

5. The method of claim 1, wherein, The temperature of the flue gas to be treated entering the flue is controlled to be 110~180℃.

6. The method of claim 1, wherein, The temperature of the flue gas to be treated entering the flue is controlled to be 140±5℃.

7. The method of claim 1, wherein, The temperature of the flue gas after ozone oxidation treatment entering the CFB semi-dry system is controlled to be 65~95℃.

8. The method of claim 1, wherein, Nitrogen oxides NO in the flue gas to be treated x = 150 ~ 380 mg / Nm 3 , SO2 = 600 ~ 2200 mg / Nm 3 .

9. The method of claim 1, wherein, Ammonia oxides NO in the flue gas to be treated x = 270 mg / Nm 3 , SO2 = 1450 mg / Nm 3 .

10. The method of claim 1, wherein, The 03+CFB semi-dry system adopted needs to meet the condition that the NO concentration of the outlet flue gas is not higher than 50 mg / Nm 3 or the NO2 concentration of the outlet flue gas is not higher than 65 mg / Nm 3 .

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