Process and device for disposing nitrogen oxides in the medium temperature section of incineration

Abstract

The present application relates to a kind of process and its device for disposing nitrogen oxide in incineration medium temperature section flue gas, belong to flue gas processing technical field.The present application uses carbon reduction technology to process nitrogen oxide in incineration flue gas, overcome the shortcomings of existing SNCR technology, such as low denitration efficiency, ammonia escape risk, large SCR equipment investment, high operating cost and the like.The modified carbon reducing agent provided in the present application exhibits many advantages and significant progress in the process of disposing nitrogen oxide in incineration medium temperature section flue gas, and its advantages mainly include high efficiency reducing property, high thermal stability, high safety, excellent anti-poisoning ability and good catalytic activity.The combined effect of these advantages enables the modified carbon reducing agent to more efficiently remove nitrogen oxides during flue gas denitration while maintaining a longer service life and stable performance.

Description

Technical Field

[0001] This invention belongs to the field of flue gas treatment technology, and relates to a process and apparatus for incinerating nitrogen oxides in medium-temperature flue gas. Background Technology

[0002] Currently, common incineration processes for nitrogen oxide (NOx) treatment employ ammonia reduction (or urea reduction). NOx compounds are non-selectively reduced to nitrogen at high temperatures. This process has strict requirements on the amount of ammonia or urea solution added; excessive ammonia can cause ammonia escape, leading to secondary pollution of the flue gas. The NOx removal efficiency of this process is approximately 50%. To meet flue gas emission standards, some companies use a combined SNCR+SCR denitrification process. Because the SCR process has high requirements for dust content in the flue gas, this device is placed after a bag filter. The temperature in this process section is below 200℃, while the temperature of general denitrification catalysts is above 260℃, and vanadium-titanium catalysts require above 320℃. Therefore, the flue gas after the bag filter requires secondary heating, consuming a large amount of heat and resulting in excessively high denitrification costs. With increasingly stringent flue gas emission standards and the widespread use of online flue gas monitoring devices, this combined denitrification process has been adopted by some companies in recent years.

[0003] NO is a colorless, odorless, and tasteless gas, slightly soluble in water, soluble in ethanol and nitric acid. It slowly oxidizes to NO2 in air, reacts with oxidizing agents to form NO2, and reacts with reducing agents to form N2. NO2 is soluble in water and nitric acid, reacts with water to form HNO3 and HNO2, reacts with bases and acid salts of strong bases to form nitrates and nitrites, and is reduced to N2 with reducing agents.

[0004] NO x It originates from the combustion of nitrogen-containing compounds, such as flue gas from coal combustion in thermal power plants, incineration of hazardous waste (solid, liquid, and gaseous nitrogen-containing waste), incineration of municipal solid waste and sludge, and vehicle exhaust. In the presence of NO... x Among exhaust gases, the most harmful to the natural environment and human survival are NO and NO2, along with small amounts of other nitrogen oxides, collectively referred to as NO. x Whether it's the incineration industry or the industrial production and use of nitrite, nitric acid, and their salts, NO is generated. x All of them have strict mandatory emission standards. Summary of the Invention

[0005] The purpose of this invention is to provide a process and apparatus for incinerating nitrogen oxides in medium-temperature flue gas, which has the characteristics of high conversion efficiency.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A process for incinerating nitrogen oxides in intermediate-temperature flue gas, the specific process flow of which is as follows.

[0008] S1. Pretreatment and feeding:

[0009] Pre-treatment of hazardous waste or solid waste involves crushing and mixing the hazardous waste or solid waste, and then feeding the pre-treated hazardous waste or solid waste into an incinerator;

[0010] S2. Incineration and secondary combustion:

[0011] Pre-treated hazardous waste or solid waste is incinerated at high temperatures in an incinerator, with the incineration temperature being 850–1000℃. The resulting flue gas is introduced into a secondary combustion chamber, where it reaches a temperature of over 1100℃ and remains for more than 2 seconds to further burn and decompose harmful substances. After recovering heat energy from the flue gas generated in the secondary combustion chamber, the flue gas at 500–550℃ is further cooled by an electrostatic precipitator to reduce particulate matter. Finally, a medium-temperature section is used to remove harmful NOx components from the flue gas using a carbon reducing agent.

[0012] The carbon reducing agent for the intermediate temperature catalytic range described in this invention is prepared by the following method.

[0013] S2.1: Immerse amorphous carbon in a 10% ammonium phosphate solution with a solid-liquid mass ratio of 1:1 for 4-6 hours. After immersion, filter the solution and dry it at 180-200℃ for 2 hours to obtain pretreated amorphous carbon.

[0014] S2.2: Dissolve graphene oxide in deionized water to prepare a graphene oxide solution with a concentration of 0.1-1 g / L, which is solution A;

[0015] S2.3: Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a CTAB solution with a concentration of 0.05–0.1 mol / L, which is solution B;

[0016] S2.4: The pretreated amorphous carbon is immersed in solution A with a solid-liquid mass ratio of 1:1. Then, 1-2 wt% of niobium oxalate ammonium is added to the solid-liquid mixture, and the mixture is sonicated at 30°C for 0.5 h. After sonication, solid-liquid mixture C is obtained.

[0017] S2.5: Cool the temperature to room temperature and add solution B dropwise to the solid-liquid mixture C, wherein the volume ratio of solution A to solution B is 2:1. Stir at 150 r / min while adding the solution. After the addition is complete, continue stirring for 0.5 h to obtain solid-liquid mixture D.

[0018] S2.6: The solid-liquid mixture D is placed in a homogenizer and homogenized at 3-5 MPa for 20-30 min to obtain mixture F. After drying at 80℃ for 12 h, it is calcined at 200℃ for 2 h to obtain the carbon reducing agent for the medium temperature range.

[0019] S3. Flue gas purification:

[0020] The flue gas that has undergone secondary combustion is purified by dust removal and desulfurization processes to remove particulate matter or inorganic salts from the flue gas.

[0021] S4. Residue Treatment:

[0022] Collect the residue generated during the incineration process, and carry out harmless treatment and resource utilization of the residue.

[0023] Furthermore, the oxygen content of the dry flue gas in the secondary combustion chamber of S2 is 6% to 10%.

[0024] Furthermore, the amorphous carbon in S2.1 is either coke or activated carbon.

[0025] Furthermore, in S2.1, ammonium phosphate is either monoammonium phosphate or diammonium phosphate.

[0026] Furthermore, in step S2.5, solution B is added at a rate of 60 mL / min. An apparatus for incinerating nitrogen oxides in intermediate-temperature flue gas includes a carbon reducing agent storage chamber, a carbon reducing agent temporary storage chamber, and a carbon reducing agent reactor.

[0027] Furthermore, the carbon reducing agent storage chamber is located above the carbon reducing agent temporary storage chamber, with a first gate valve between them. The carbon reducing agent storage chamber is fixedly connected above the carbon reducing agent temporary storage chamber, with a first gate valve between them. The carbon reducing agent temporary storage chamber is fixedly connected above the carbon reducing agent reactor, with a second gate valve between them. A third gate valve is located below the carbon reducing agent reactor.

[0028] Furthermore, the carbon reducing agent reactor is equipped with a soot blowing device.

[0029] Furthermore, the carbon reducing agent reactor is equipped with a medium-temperature carbon reducing agent.

[0030] This invention employs carbon reduction technology to treat nitrogen oxides in incineration flue gas. More specifically, it describes a method and complete set of equipment for treating nitrogen oxides in incineration flue gas using modified coke or modified activated carbon as a reducing agent. This overcomes the shortcomings of existing SNCR technology, such as low denitrification efficiency, ammonia escape risk, and high investment and operating costs of SCR equipment.

[0031] Regarding NO xTo address the aforementioned problems with existing technologies, this invention, based on physicochemical principles, employs a "carbon reduction method" to treat the NO in the plant. x Exhaust gas, under certain conditions, NO x The following reduction reaction occurs when the reactant coke added to the device is reacted with the following:

[0032] 2NO + C → CO2↑ + N2↑

[0033] 2NO 2+ 2C→2CO2↑+N2↑

[0034] In hazardous waste incineration projects, the materials are complex, and the nitrogen oxide content in the flue gas is unstable. Based on actual operating conditions, the flue gas temperature at the secondary combustion chamber outlet is above 1100℃. The nitrogen oxides generated during combustion are mainly nitric oxide, accounting for approximately 90%–95%. x Concentrations can reach 1500 mg / m³ 3 The oxygen content in incineration flue gas is 6%–10%. Under low oxygen partial pressure, NO continues to be slowly oxidized to NO2, resulting in a long reaction time and a low conversion rate under normal operating conditions. In conventional flue gas purification processes, nitric oxide is poorly soluble in water, forming nitrite. Even if a small amount of nitrite is formed, it is easily decomposed under medium-temperature conditions. Using alkaline water washing to remove nitrogen oxides from incineration exhaust gas and achieve emission standards in flue gas with high NOx levels is essentially impossible.

[0035] The modified carbon reducing agent provided by this invention exhibits numerous advantages and significant advancements in the incineration process for treating nitrogen oxides in medium-temperature flue gas. Its advantages primarily include high reducing efficiency, high thermal stability, high safety, excellent resistance to poisoning, and good catalytic activity. The combined effect of these advantages enables the modified carbon reducing agent to remove nitrogen oxides more efficiently during flue gas denitrification, while maintaining a long service life and stable performance.

[0036] The modified carbon reducing agent exhibits higher reducing activity, effectively promoting the reduction reaction of nitrogen oxides in flue gas and improving denitrification efficiency. Through specific modification treatment, the structure of the carbon reducing agent is optimized, and its thermal stability is significantly improved, enabling it to maintain stable reducing performance in the mid-temperature combustion environment and enhancing its resistance to poisoning. This makes it particularly suitable for the one-time removal of high NOx levels in flue gas, replacing the current SNCR+SCR combined denitrification process. During the modification process, complex interactions exist between the added ammonium phosphate, graphene oxide, hexadecyltrimethylammonium bromide, and niobium oxalate.

[0037] This invention first activates the amorphous carbon surface through soaking in ammonium phosphate, increasing its specific surface area and porosity to provide more adsorption sites for subsequent modified substances. The introduction of graphene oxide not only enhances the structural strength of the carbon reducing agent but also promotes electron transfer through its excellent conductivity, accelerating the reduction reaction rate. CTAB, as a surfactant, reduces the surface tension of the solution, promoting the uniform distribution of modified substances such as ammonium niobate on the carbon surface. In addition to its surfactant role, CTAB also plays an important modifying role; its cationic groups can interact with the negative charge on the carbon surface to form a stable adsorption layer, further enhancing the stability and catalytic activity of the carbon reducing agent. Simultaneously, the addition of ammonium niobate can form specific catalytically active sites, further improving the reduction performance. The niobium element in ammonium niobate has high catalytic activity and can react with nitrogen oxides in flue gas, promoting their reduction and decomposition. Meanwhile, the introduction of niobium oxalate ammonium also improves the microstructure of the carbon reducing agent surface, increases the number and distribution of catalytic sites, thereby improving catalytic efficiency. Furthermore, there is a synergistic mechanism between CTAB and niobium oxalate ammonium during the modification process. The surface activity of CTAB can promote the uniform distribution and adsorption of niobium oxalate ammonium on the carbon surface, allowing the catalytic sites in niobium oxalate ammonium to be fully exposed and play their role. At the same time, the cationic groups of CTAB can also interact with the anions in niobium oxalate ammonium to form stronger adsorption force and a more stable catalytic structure. This synergistic mechanism not only improves the catalytic activity of the carbon reducing agent, but also enhances its resistance to poisoning and stability.

[0038] The preparation process, including stirring, sonication, and homogenization, ensures the uniform distribution and full reaction of the modified material within the carbon reducing agent, thereby improving the overall performance. The final drying and calcination steps remove residual moisture and volatile substances, forming a stable catalytic structure and guaranteeing the long-term effectiveness of the carbon reducing agent.

[0039] In the apparatus of this invention, the treated carbon reducing agent is loaded into a steel reactor. The reactor interior is constructed with refractory insulation material, the thickness of which is designed to vary according to different operating temperatures. The containers holding the reducing agent are equipped with porous, high-temperature resistant, and corrosion-resistant stainless steel or high-temperature resistant cast iron mesh plates at both the flue gas inlet and outlet ends to ensure that the carbon reducing agent is not blown away by the flue gas. The shape and size of the mesh plates are matched to the denitrification reactor. A double-door carbon reducing agent replenishment chamber is located at the top of the reactor to periodically replenish the consumed carbon reducing agent. The carbon chamber is as follows... Figure 1As shown, a fireproof first gate valve is installed between the carbon reduction reactor and the carbon reducing agent temporary storage chamber, and a second gate valve is installed between the carbon reducing agent temporary storage chamber and the carbon reducing agent storage chamber. Under normal circumstances, the reducing agent is replenished once a day. The replenishment process is as follows: first, place the carbon reducing agent in the carbon reducing agent storage chamber; open the second gate valve, allowing the material to fall into the carbon reducing agent temporary storage chamber; close the first gate valve; open the first gate valve again, allowing the material to fall into the carbon reduction reactor; close the first gate valve, and repeat this replenishment cycle. During idle periods, the carbon reducing agent is placed in the carbon reducing agent temporary storage chamber. To ensure the stability of the carbon reducing agent denitrification efficiency, the reactor is equipped with a soot blowing device. After a period of operation, the soot blowing device is activated to allow the fine dust adhering to the catalyst surface to be discharged with the flue gas. The soot blowing device can use compressed air, nitrogen, or steam. A more economical and effective soot blowing method is to use steam generated by the incineration system boiler, with the soot blowing airflow direction consistent with the flue gas flow direction.

[0040] The beneficial effects of this invention are:

[0041] The modified carbon reducing agent provided by this invention exhibits numerous advantages and significant advancements in the incineration process for treating nitrogen oxides in medium-temperature flue gas. These advantages primarily include high reducing efficiency, high thermal stability, excellent resistance to poisoning, and good catalytic activity. The combined effect of these advantages enables the modified carbon reducing agent to remove nitrogen oxides more efficiently during flue gas denitrification, while maintaining a long service life and stable performance. Attached Figure Description

[0042] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0043] Figure 1 A device for incinerating nitrogen oxides in intermediate-temperature flue gas;

[0044] Explanation of reference numerals in the attached figures:

[0045] Figure 1 In the middle section: 1. Carbon reducing agent storage bin; 2. First gate valve; 3. Carbon reducing agent temporary storage bin; 4. Second gate valve; 5. Carbon reducing agent for intermediate temperature section; 6. Soot blowing device; 7. Carbon reducing agent reactor; 8. Third gate valve. Detailed Implementation

[0046] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0047] Example 1

[0048] A process for incinerating nitrogen oxides in intermediate-temperature flue gas, the specific process flow of which is as follows.

[0049] S1. Pretreatment and feeding:

[0050] Pre-treatment of hazardous waste or solid waste involves crushing and mixing the hazardous waste or solid waste, and then feeding the pre-treated hazardous waste or solid waste into an incinerator;

[0051] S2. Incineration and secondary combustion:

[0052] Pre-treated hazardous waste or solid waste is incinerated at high temperature in an incinerator at 900℃. The resulting flue gas is introduced into a secondary combustion chamber, where it reaches a temperature of over 1100℃ and remains for more than 2 seconds. The dry flue gas in the secondary combustion chamber contains 8% oxygen to further burn and decompose harmful substances. After recovering heat energy from the flue gas generated in the secondary combustion chamber, the flue gas at 520℃ is further cooled by an electrostatic precipitator to reduce particulate matter. Finally, a medium-temperature section is used to remove harmful NOx components from the flue gas using a carbon reducing agent.

[0053] The preparation method of the carbon reducing agent for the intermediate temperature range is as follows:

[0054] S2.1: Soak coke in a 10% monoammonium phosphate solution with a solid-liquid mass ratio of 1:1 for 5 hours. After soaking, filter the coke and dry it at 200°C for 2 hours to obtain pretreated amorphous carbon.

[0055] S2.2: Dissolve graphene oxide in deionized water to prepare a graphene oxide solution with a concentration of 1 g / L, which is solution A;

[0056] S2.3: Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a CTAB solution with a concentration of 0.1 mol / L, which is solution B;

[0057] S2.4: The pretreated amorphous carbon is immersed in solution A with a solid-liquid mass ratio of 1:1. Then, 2 wt% of niobium oxalate ammonium is added to the solid-liquid mixture, and the mixture is sonicated at 30°C for 0.5 h. After sonication, solid-liquid mixture C is obtained.

[0058] S2.5: Cool the temperature to room temperature, add solution B dropwise to the solid-liquid mixture C at a rate of 60 mL / min, wherein the volume ratio of solution A to solution B is 2:1, and stir at a speed of 150 r / min while adding the solution. After the addition is completed, continue stirring for 0.5 h to obtain solid-liquid mixture D.

[0059] S2.6: The solid-liquid mixture D is placed in a homogenizer and homogenized at 5 MPa for 20 min to obtain mixture F. After drying at 80℃ for 12 h, it is calcined at 200℃ for 2 h to obtain the carbon reducing agent for the medium temperature range.

[0060] S3. Flue gas purification:

[0061] The flue gas that has undergone secondary combustion is purified by dust removal and desulfurization processes to remove particulate matter and organic pollutants from the flue gas.

[0062] S4. Residue Treatment:

[0063] Collect the residue generated during the incineration process, and carry out harmless treatment and resource utilization of the residue.

[0064] Example 2

[0065] A process for incinerating nitrogen oxides in intermediate-temperature flue gas, the specific process flow of which is as follows.

[0066] S1. Pretreatment and feeding:

[0067] Pre-treatment of hazardous waste or solid waste involves crushing and mixing the hazardous waste or solid waste, and then feeding the pre-treated hazardous waste or solid waste into an incinerator;

[0068] S2. Incineration and secondary combustion:

[0069] Pre-treated hazardous waste or solid waste is incinerated at high temperature in an incinerator at 850℃. The resulting flue gas is introduced into a secondary combustion chamber, where it reaches a temperature of over 1100℃ and remains for more than 2 seconds. The dry flue gas in the secondary combustion chamber contains 6% oxygen to further burn and decompose harmful substances. The flue gas from the secondary combustion chamber is then cooled to 500℃ after heat recovery in a waste heat boiler. After further reducing dust content in the flue gas through an electrostatic precipitator, a medium-temperature section is used to remove harmful NOx components from the flue gas using a carbon reducing agent.

[0070] The preparation method of the carbon reducing agent for the intermediate temperature range is as follows:

[0071] S2.1: Activated carbon is soaked in a 10% diammonium phosphate solution with a solid-liquid mass ratio of 1:1 for 4 hours. After soaking, it is filtered and dried at 180°C for 2 hours to obtain pretreated amorphous carbon.

[0072] S2.2: Dissolve graphene oxide in deionized water to prepare a graphene oxide solution with a concentration of 0.1 g / L, which is solution A;

[0073] S2.3: Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a CTAB solution with a concentration of 0.05 mol / L, which is solution B;

[0074] S2.4: The pretreated amorphous carbon is immersed in solution A with a solid-liquid mass ratio of 1:1. Then, 1 wt% of niobium oxalate ammonium is added to the solid-liquid mixture, and the mixture is sonicated at 30°C for 0.5 h. After sonication, solid-liquid mixture C is obtained.

[0075] S2.5: Cool the temperature to room temperature, add solution B dropwise to the solid-liquid mixture C at a rate of 60 mL / min, wherein the volume ratio of solution A to solution B is 2:1, and stir at a speed of 150 r / min while adding the solution. After the addition is completed, continue stirring for 0.5 h to obtain solid-liquid mixture D.

[0076] S2.6: The solid-liquid mixture D is placed in a homogenizer and homogenized at 3 MPa for 30 min to obtain mixture F. After drying at 80℃ for 12 h, it is calcined at 200℃ for 2 h to obtain the carbon reducing agent for the medium temperature range.

[0077] S3. Flue gas purification:

[0078] The flue gas that has undergone secondary combustion is purified by dust removal and desulfurization processes to remove particulate matter and inorganic salts from the flue gas.

[0079] S4. Residue Treatment:

[0080] Collect the residue generated during the incineration process, and carry out harmless treatment and resource utilization of the residue.

[0081] Example 3

[0082] A process for incinerating nitrogen oxides in intermediate-temperature flue gas, the specific process flow of which is as follows.

[0083] S1. Pretreatment and feeding:

[0084] Pre-treatment of hazardous waste or solid waste involves crushing and mixing the hazardous waste or solid waste, and then feeding the pre-treated hazardous waste or solid waste into an incinerator;

[0085] S2. Incineration and secondary combustion:

[0086] Pre-treated hazardous waste or solid waste is incinerated at high temperature in an incinerator at 1000℃. The resulting flue gas is introduced into a secondary combustion chamber, where it reaches a temperature of over 1100℃ and remains for more than 2 seconds. The dry flue gas in the secondary combustion chamber contains 10% oxygen to further burn and decompose harmful substances. The flue gas from the secondary combustion chamber is then cooled to 500℃ after heat recovery in a waste heat boiler. After further reducing dust content in the flue gas through an electrostatic precipitator, a medium-temperature section is used to remove harmful NOx components from the flue gas using a carbon reducing agent.

[0087] The preparation method of the carbon reducing agent for the intermediate temperature range is as follows:

[0088] S2.1: The coke was soaked in a 10% monoammonium phosphate solution with a solid-liquid mass ratio of 1:1 for 6 hours. After soaking, the coke was filtered and dried at 200°C for 2 hours to obtain pretreated amorphous carbon.

[0089] S2.2: Dissolve graphene oxide in deionized water to prepare a graphene oxide solution with a concentration of 0.5 g / L, which is solution A;

[0090] S2.3: Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a CTAB solution with a concentration of 0.075 mol / L, which is solution B;

[0091] S2.4: The pretreated amorphous carbon is immersed in solution A with a solid-liquid mass ratio of 1:1. Then, 2 wt% of niobium oxalate ammonium is added to the solid-liquid mixture, and the mixture is sonicated at 30°C for 0.5 h. After sonication, solid-liquid mixture C is obtained.

[0092] S2.5: Cool the temperature to room temperature, add solution B dropwise to the solid-liquid mixture C at a rate of 60 mL / min, wherein the volume ratio of solution A to solution B is 2:1, and stir at a speed of 150 r / min while adding the solution. After the addition is completed, continue stirring for 0.5 h to obtain solid-liquid mixture D.

[0093] S2.6: The solid-liquid mixture D is placed in a homogenizer and homogenized at 5 MPa for 20 min to obtain mixture F. After drying at 80℃ for 12 h, it is calcined at 200℃ for 2 h to obtain the carbon reducing agent for the medium temperature range.

[0094] S3. Flue gas purification:

[0095] The flue gas that has undergone secondary combustion is purified by dust removal and desulfurization processes to remove particulate matter and organic pollutants from the flue gas.

[0096] S4. Residue Treatment:

[0097] Collect the residue generated during the incineration process, and carry out harmless treatment and resource utilization of the residue.

[0098] Comparative Example 1

[0099] This comparative example uses only coke as a reducing agent; the remaining steps are the same as in Example 1.

[0100] Comparative Example 2

[0101] In this comparative example, the preparation of the carbon reducing agent in the medium temperature range does not involve soaking in ammonium phosphate solution; the remaining steps are the same as in Example 1.

[0102] Comparative Example 3

[0103] In this comparative example, graphene oxide was not added during the preparation of the carbon reducing agent in the intermediate temperature range; the remaining steps were the same as in Example 1.

[0104] Comparative Example 4

[0105] In this comparative example, CTAB was not added during the preparation of the carbon reducing agent in the intermediate temperature range, and the remaining steps were the same as in Example 1.

[0106] Comparative Example 5

[0107] In this comparative example, niobium oxalate ammonium was not added in the preparation of the carbon reducing agent in the intermediate temperature range, and the remaining steps were the same as in Example 1.

[0108] The nitrogen oxide removal rate of the flue gas emitted in the examples and comparative examples was tested. The emission standards for the flue gas were based on GB18484—2020 "Standard for Pollution Control of Hazardous Waste Incineration". The test results are summarized in the table below.

[0109] <![CDATA[NO x Removal rate (%) Example 1 99.3 Example 2 98.7 Example 3 98.9 Comparative Example 1 91.1 Comparative Example 2 95.3 Comparative Example 3 96.2 Comparative Example 4 95.0 Comparative Example 5 94.8

[0110] Experimental data show that the carbon reducing agent for the intermediate temperature range prepared in this invention effectively improves NO production. x Removal rate.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention are within the scope of the present invention.

Claims

1. A process for incinerating nitrogen oxides in intermediate-temperature flue gas, characterized in that, The specific process flow is as follows. S1. Pretreatment and feeding: Pre-treatment of hazardous waste or solid waste involves crushing and mixing the hazardous waste or solid waste, and then feeding the pre-treated hazardous waste or solid waste into an incinerator; S2. Incineration and secondary combustion: Pre-treated hazardous waste or solid waste is incinerated at high temperature in an incinerator, with an incineration temperature of 850–1000℃. The resulting flue gas is introduced into a secondary combustion chamber, where it reaches a temperature of over 1100℃ and remains for more than 2 seconds to further burn and decompose harmful substances. After recovering heat energy from the flue gas generated in the secondary combustion chamber, the flue gas at 500–550℃ is passed through a medium-temperature section where a carbon reducing agent is used to remove harmful NOx components from the flue gas. The preparation method of the carbon reducing agent in the intermediate temperature range of S2 is as follows: S2.1: Immerse amorphous carbon in a 10% ammonium phosphate solution with a solid-liquid mass ratio of 1:1 for 4-6 hours. After immersion, filter the solution and dry it at 180-200℃ for 2 hours to obtain pretreated amorphous carbon. S2.2: Dissolve graphene oxide in deionized water to prepare a graphene oxide solution with a concentration of 0.1-1 g / L, which is solution A; S2.3: Dissolve hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a CTAB solution with a concentration of 0.05–0.1 mol / L, which is solution B; S2.4: The pretreated amorphous carbon is immersed in solution A with a solid-liquid mass ratio of 1:

1. Then, 1-2 wt% of niobium oxalate ammonium is added to the solid-liquid mixture, and the mixture is sonicated at 30°C for 0.5 h. After sonication, solid-liquid mixture C is obtained. S2.5: Cool the temperature to room temperature and add solution B dropwise to the solid-liquid mixture C, wherein the volume ratio of solution A to solution B is 2:

1. Stir at 150 r / min while adding the solution. After the addition is complete, continue stirring for 0.5 h to obtain solid-liquid mixture D. S2.6: The solid-liquid mixture D is placed in a homogenizer and homogenized at 0.3-0.5 MPa for 20-30 min to obtain mixture F. After drying at 80℃ for 12 h, it is calcined at 200℃ for 2 h to obtain the carbon reducing agent for the medium temperature range. S3. Flue gas purification: The flue gas that has undergone secondary combustion is purified by a waste heat boiler and an electrostatic precipitator to remove most of the particulate matter from the flue gas.

2. The process for incinerating nitrogen oxides in intermediate-temperature flue gas according to claim 1, characterized in that, The oxygen content of the dry flue gas in the secondary combustion chamber of S2 is 6% to 10%.

3. The process for incinerating nitrogen oxides in intermediate-temperature flue gas according to claim 1, characterized in that, The amorphous carbon in S2.1 is either coke or activated carbon.

4. The process for incinerating nitrogen oxides in intermediate-temperature flue gas according to claim 1, characterized in that, The ammonium phosphate in S2.1 is either monoammonium phosphate or diammonium phosphate.

5. The process for incinerating nitrogen oxides in intermediate-temperature flue gas according to claim 1, characterized in that, The rate at which solution B is added in S2.5 is 60 mL / min.

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