A lime kiln flue gas denitration treatment method

Abstract

The application relates to the technical field of denitration, and specifically discloses a lime kiln flue gas denitration treatment method. The lime kiln flue gas denitration treatment method specifically comprises the following steps in sequence: SNCR and SCR; the process parameters of the SNCR section are as follows: the flue gas temperature is 900-1200 DEG C, 10-14 wt% urea solution is sprayed, and the target denitration efficiency is 10-30%; the process parameters of the SCR section are as follows: the flue gas temperature is 180-220 DEG C, 17-22 wt% ammonia water is used as a reducing agent, a honeycomb catalyst is used, and the space velocity is 3000-5000 h-1 1 ; the honeycomb catalyst is prepared from the following components: vanadium pentoxide, titanium dioxide, zinc-aluminum hydrotalcite and stearic acid. The technical scheme provided by the application has excellent denitration performance in the denitration treatment of lime kiln flue gas; the denitration system can be operated for a long time, and the denitration efficiency is relatively high after long-time continuous operation.

Description

Technical Field

[0001] This application relates to the technical field of denitrification, specifically to a method for denitrification treatment of flue gas from a lime kiln. Background Technology

[0002] With increasingly stringent environmental regulations, denitrification of industrial kiln flue gas has become a key focus of air pollution control. Currently, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are the mainstream denitrification technologies. SCR technology has high denitrification efficiency (up to 90% or more), but its investment and operating costs are high, and the catalyst is prone to poisoning and deactivation. SNCR technology has lower costs, but its denitrification efficiency is limited (usually 30%-70%), and ammonia slip is a serious problem. In addition, lime kiln flue gas is characterized by large temperature fluctuations and high dust content, which places higher demands on the adaptability of denitrification technologies. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a method for denitrification treatment of flue gas from lime kilns.

[0004] This application provides a method for denitrification treatment of flue gas from a lime kiln, which specifically includes the following steps in sequence: SNCR treatment and SCR treatment;

[0005] The process parameters for the SNCR section are: flue gas temperature 900-1200℃, injection of 10-14wt% urea solution, and target denitrification efficiency of 10-30%.

[0006] The process parameters for the SCR section are as follows: flue gas temperature 180-220℃, 17-22wt% ammonia water as the reducing agent, honeycomb catalyst, and space velocity 3000-5000 h⁻¹. -1 ;

[0007] The honeycomb catalyst is prepared from the following components in parts by weight: 3-10 parts vanadium pentoxide, 20-30 parts titanium dioxide, 40-50 parts zinc aluminum hydrotalcite, and 1-8 parts stearic acid.

[0008] The denitrification process and principle adopted in this application are as follows: urea solution is sprayed into the SNCR stage at around 900-1200℃ to initially remove 10%-30% of NOx; the SCR stage further denitrates under the action of a catalyst, with a total efficiency of over 90%.

[0009] In the process of in-furnace denitrification in the SCR section, honeycomb catalysts, due to their advantages such as large specific surface area, high mechanical strength, low fluid resistance, and uniform distribution of active components, have become a key core component in the SCR denitrification system, which can significantly improve the efficiency and stability of the denitrification reaction. Under the action of the denitrification catalyst of this application, the reducing agent (ammonia) reacts chemically with nitrogen oxides (NOx) in the flue gas under specific temperature conditions, reducing NOx to harmless nitrogen and water. At the same time, it can greatly reduce ammonia escape, reduce the corrosion and ash accumulation of ammonium salts on the pipe walls and furnace, thereby reducing the maintenance cost of the equipment.

[0010] Preferably, the process parameters of the SNCR section are: flue gas temperature 900-1200℃, injection of 10-14wt% urea solution, and target denitrification efficiency of 15-25%.

[0011] Preferably, the process parameters of the SNCR section are: flue gas temperature 900-1200℃, injection of 11-13wt% urea solution, and target denitrification efficiency of 17-22%.

[0012] In one specific implementation, the process parameters of the SNCR section are as follows: the flue gas temperature can be 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, or 1200℃, and a 10-14wt% urea solution is injected. The target denitrification efficiency can be 10%, 15%, 20%, 25%, or 30%.

[0013] Urea decomposes into ammonia at high temperatures, which then reacts with NO. x Reaction: 1 mol of urea decomposes into 2 mol of ammonia, which can remove 2 mol of NO. x The theoretical injection volume is determined by NO. x The concentration and target denitrification efficiency determine the urea solution injection rate: The formula for calculating the urea solution injection rate is: Urea solution flow rate (kg / h) = Q × C NOx ×η×M 尿素 ×10 -6 / (2×M NO2 ×ρ×X); Parameter description: Q: Flue gas flow rate (Nm³ / h); C NOx Initial NOx concentration (mg / Nm³, as NO2); η target denitrification efficiency; M 尿素 Molar mass of urea (60 g / mol); M NO2 : Molar mass of NO2 (46 g / mol); ρ: Mass concentration of urea solution; X: Efficiency of urea conversion to NH3 (taken as 0.9, considering that some urea is not completely decomposed).

[0014] Preferably, the process parameters of the SCR section are: flue gas temperature of 180-220℃; 18-21wt% ammonia water as the reducing agent; outlet pressure of 0.9-1.2MPa; and pump flow rate of 0.6-0.9m³ / h. 3 The air is pumped to the spray gun at a flow rate of 0.35-0.45 MPa and then atomized by compressed air at the spray gun inlet before being sprayed into the ammonia evaporator; the air velocity is 3500-4500 h⁻¹. -1 .

[0015] In one specific implementation scheme, the flue gas temperature is 220°C, 20wt% ammonia water is used as the reducing agent, and the space velocity is 4000 h⁻¹. -1 .

[0016] Preferably, the honeycomb catalyst is prepared using the following components in parts by weight: 5-8 parts vanadium pentoxide, 22-28 parts titanium dioxide, 42-48 parts zinc aluminum hydrotalcite, and 3-6 parts stearic acid.

[0017] The titanium dioxide has a particle size of 50-150 nm.

[0018] In one specific embodiment, the honeycomb catalyst is prepared using the following components in parts by weight: 6.5 parts vanadium pentoxide, 25 parts titanium dioxide, 45 parts zinc aluminum hydrotalcite, and 4 parts stearic acid.

[0019] Preferably, the preparation method of the zinc-aluminum hydrotalcite specifically includes the following steps in sequence: In a constant temperature water bath at 40-70℃, a mixed salt solution containing 0.6-1.0 mol / L soluble zinc salt and 0.1-0.3 mol / L soluble aluminum salt, and a NaOH alkaline solution at 0.8-1.2 mol / L are simultaneously added dropwise to a reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 50-80℃ for 2-8 hours. After washing, filtering, and drying, the product is obtained.

[0020] Preferably, the preparation method of the honeycomb catalyst is as follows: weigh the corresponding weights of each raw material component, mix them evenly, grind them so that the average particle size of the raw material particles is ≤5μm, add 2-8w / w% oxalic acid to the raw material system, and mix evenly; according to the molding requirements, use an extruder to extrude the mud, and then dry and calcine it to obtain the honeycomb catalyst.

[0021] Preferably, the drying conditions are: temperature 60-80℃, time 12-24h; the calcination conditions are: heating to 500-600℃ at a rate of 3-10℃ / min, and holding at that temperature for 3-5h.

[0022] Preferably, the specifications of the honeycomb catalyst are: 30×30 pores, pore diameter of 4-8 mm, and wall thickness of 0.8-1.2 mm.

[0023] Preferably, the lime kiln flue gas denitrification treatment method utilizes a lime kiln flue gas denitrification system for denitrification treatment, the lime kiln flue gas denitrification system comprising an SNCR reaction section, an SCR reaction section, and a chimney connected in sequence;

[0024] The SNCR section is located in the kiln tail flue and is equipped with ultrasonic atomizing nozzles; the SCR section adopts a modular catalyst bed and has an ash hopper at the bottom.

[0025] In summary, the technical solution of this application has the following effects:

[0026] The denitrification method provided in this application couples SNCR and SCR treatments, and optimizes the flue gas temperature, urea usage, and denitrification efficiency of the SNCR treatment; and optimizes the temperature, honeycomb catalyst, and space velocity in the SCR treatment. This can effectively improve denitrification efficiency, reduce the usage of denitrification agents such as urea or ammonia, and save operating costs.

[0027] This application significantly reduces ammonia escape due to the improved denitrification efficiency, thereby reducing corrosion and ash accumulation on pipe walls and furnaces, and indirectly lowering equipment investment and maintenance costs.

[0028] The denitrification method provided in this application can meet the requirements of long-term operation of the denitrification system, and the denitrification efficiency is high after continuous operation for a long time. Detailed Implementation

[0029] The present application will be further described in detail below with reference to embodiments, comparative examples and performance test results. These embodiments should not be construed as limiting the scope of protection claimed in this application. Example Example 1

[0030] Example 1 provides a method for denitrification treatment of flue gas from lime kilns.

[0031] The flue gas parameters are: flue gas volume to be treated is 120,000 m³. 3 / h, initial concentration of nitrogen oxides (NOx) 323.6 mg / Nm³ 3 Inlet sulfur dioxide concentration: 9.48 mg / Nm³ 3 .

[0032] The lime kiln flue gas denitrification treatment system includes an SNCR reaction section, an SCR reaction section, and a chimney connected in sequence; the SNCR section is located in the kiln tail flue and is equipped with ultrasonic atomizing nozzles; the SCR section adopts a modular catalyst bed and has an ash hopper at the bottom.

[0033] The specific steps of the denitrification method for lime kiln flue gas are as follows:

[0034] (1) SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 900℃, a 12% urea solution is injected. The target denitrification efficiency is 20%, and the injection rate is 46.9 kg / h.

[0035] The formula for calculating the amount of urea solution injected is as follows: Urea decomposes into ammonia at high temperature, which reacts with NO... x Reaction: 1 mol of urea decomposes into 2 mol of NH3, which removes 2 mol of NO. x The theoretical injection volume is determined by NO. x The concentration and target denitrification efficiency determine the urea solution flow rate (kg / h) = Q × C NOx ×η×M 尿素× 10 -6 / (2×M NO2 ×ρ×X); Parameter description: Q: Flue gas flow rate (Nm³ / h); C NOx Initial NOx concentration (mg / Nm³, as NO2); η target denitrification efficiency; M 尿素 Molar mass of urea (60 g / mol); M NO2 : Molar mass of NO2 (46 g / mol); ρ: Mass concentration of urea solution; X: Efficiency of urea conversion to NH3 (taken as 0.9, considering that some urea is not completely decomposed).

[0036] (2) SCR treatment: The flue gas enters the SCR section, the flue gas temperature in the furnace is 200℃, 20% ammonia water is used as the reducing agent, and the outlet pressure is 1.1MPa, the pump flow rate is 0.75m³ / h 3 The compressed air is pumped at a rate of / h to the spray gun, atomized by compressed air at the spray gun inlet at 0.4MPa, and then sprayed into the ammonia water evaporator made of 304 stainless steel, where denitrification takes place; a honeycomb 30×30-pore catalyst is used, with a space velocity of 4000 h⁻¹. -1 An acoustic soot blower is installed to prevent catalyst blockage.

[0037] The preparation method of zinc-aluminum hydrotalcite specifically includes the following steps: Under a constant temperature water bath of 65°C, a mixed salt solution containing 0.8 mol / L soluble zinc salt and 0.2 mol / L soluble aluminum salt and 1 mol / L NaOH alkaline solution are simultaneously added dropwise to a reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 65°C for 5 hours, washed, filtered, and dried at 60°C for 24 hours to obtain the final product.

[0038] The preparation method of the honeycomb catalyst is as follows: 6.5 kg of vanadium pentoxide, 25 kg of titanium dioxide, 45 kg of zinc aluminum hydrotalcite, and 4 kg of stearic acid are weighed out respectively, mixed evenly, and ground to make the average particle size of the raw materials ≤ 5 μm. 6 w / w% oxalic acid of the raw material system is added and mixed evenly. According to the molding requirements, the mud is extruded using an extruder, and then dried at 70℃ for 18 h. The temperature is then increased to 550℃ at a rate of 5℃ / min and calcined for 4 h to obtain a honeycomb catalyst with 30×30 pores, a pore diameter of 6 mm, and a wall thickness of 1 mm.

[0039] Examples 2-5

[0040] Examples 2-5 provide a method for denitrification treatment of flue gas from lime kilns.

[0041] The specific difference between the above embodiment and Embodiment 1 is that the process parameters of the SNCR segment are different, as shown below.

[0042] In Example 2: SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 900℃, a 12% urea solution is injected. The target denitrification efficiency is 10%, and the injection rate is 23.4 kg / h.

[0043] In Example 3: SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 950℃, a 12% urea solution is injected. The target denitrification efficiency is 15%, and the injection rate is 35.1 kg / h.

[0044] In Example 4: SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 1000℃, a 12% urea solution is injected. The target denitrification efficiency is 25%, and the injection rate is 58.6 kg / h.

[0045] In Example 5: SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 1050℃, a 12% urea solution is injected. The target denitrification efficiency is 30%, and the injection rate is 70.3 kg / h.

[0046] All other process parameters in the above embodiments are the same as those in Embodiment 1.

[0047] Examples 6-14

[0048] Examples 6-14 provide a method for denitrification treatment of flue gas from a lime kiln.

[0049] The specific difference between the above embodiment and Embodiment 1 is that the process parameters of the SCR section are different, as shown below.

[0050] In Example 6: SCR treatment: flue gas temperature in the furnace was 180°C, and space velocity was 5000 h⁻¹. -1 .

[0051] In Example 7: SCR treatment: flue gas temperature in the furnace was 200°C, and space velocity was 3000 h⁻¹. -1 .

[0052] In Example 8: SCR treatment: flue gas temperature in the furnace was 210°C, and space velocity was 4500 h⁻¹. -1 .

[0053] In Example 9: SCR treatment: flue gas temperature in the furnace was 220°C, and space velocity was 3500 h⁻¹. -1 .

[0054] In Example 10, the honeycomb catalyst was prepared by weighing 5 kg of vanadium pentoxide, 28 kg of titanium dioxide, 42 kg of zinc aluminum hydrotalcite, and 6 kg of stearic acid respectively to prepare the honeycomb catalyst.

[0055] In Example 11, the honeycomb catalyst was prepared by weighing 8 kg of vanadium pentoxide, 22 kg of titanium dioxide, 48 kg of zinc aluminum hydrotalcite, and 3 kg of stearic acid respectively to prepare the honeycomb catalyst.

[0056] In Example 12, the preparation method of zinc-aluminum hydrotalcite specifically includes the following steps: Under a constant temperature water bath of 65°C, a mixed salt solution containing 0.2 mol / L soluble zinc salt and 0.8 mol / L soluble aluminum salt and 1 mol / L NaOH alkaline solution are simultaneously added dropwise to a reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 65°C for 5 hours, washed, filtered, and dried at 60°C for 24 hours to obtain the final product.

[0057] In Example 13, the preparation method of zinc-aluminum hydrotalcite specifically includes the following steps: Under a constant temperature water bath of 65°C, a mixed salt solution containing 1.5 mol / L soluble zinc salt and 0.1 mol / L soluble aluminum salt and 1 mol / L NaOH alkaline solution are simultaneously added dropwise to a reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 65°C for 5 hours, washed, filtered, and dried at 60°C for 24 hours to obtain the final product.

[0058] In Example 14, the preparation method of zinc-aluminum hydrotalcite specifically includes the following steps: Under a constant temperature water bath of 65°C, a mixed salt solution containing 0.6 mol / L soluble zinc salt and 0.3 mol / L soluble aluminum salt and 1 mol / L NaOH alkaline solution are simultaneously added dropwise to a reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 65°C for 5 hours, washed, filtered, and dried at 60°C for 24 hours to obtain the final product.

[0059] All other process parameters in the above embodiments are the same as those in Embodiment 1. Comparative Example Comparative Example 1

[0060] Comparative Example 1 provides a method for denitrification treatment of flue gas from a lime kiln.

[0061] The difference between the above comparative examples and Example 1 is that the process parameters of the SNCR segment are different, as shown in Table 1.

[0062] In Comparative Example 1: SNCR treatment: When the flue gas enters the SNCR section and the flue gas temperature reaches 900℃, a 12% urea solution is injected. The target denitrification efficiency is 5%, and the injection rate is 11.7 kg / h.

[0063] All other process parameters in the above comparative examples are the same as those in Example 1.

[0064] Comparative Examples 2-4

[0065] Comparative Examples 2-4 each provide a method for denitrification treatment of flue gas from lime kilns.

[0066] The difference between the above comparative example and Example 1 is that the process parameters of the SCR section are different, as shown below.

[0067] Comparative Example 2: SCR treatment: flue gas temperature in the furnace was 180℃, and space velocity was 2500 h⁻¹. -1 .

[0068] In Comparative Example 3, the honeycomb catalyst was prepared by weighing 6.5 kg of vanadium pentoxide, 25 kg of titanium dioxide, and 4 kg of stearic acid, respectively, to prepare the honeycomb catalyst.

[0069] In Comparative Example 4, the honeycomb catalyst was prepared by weighing 6.5 kg of vanadium pentoxide, 45 kg of titanium dioxide, 25 kg of zinc aluminum hydrotalcite, and 4 kg of stearic acid respectively to prepare the honeycomb catalyst.

[0070] All other process parameters in the above comparative examples are the same as those in Example 1.

[0071] Performance testing

[0072] Before and after implementing the denitrification methods provided in the examples and comparative examples, the changes in nitrogen oxide concentration in the incinerator were monitored after denitrification treatment (continuous operation for 2 hours and continuous operation for 100 hours). The test results are shown in Table 1.

[0073] Table 1 Performance test results of the denitrification methods provided in the examples and comparative examples

[0074]

[0075] As can be seen from the test results in the table above, the technical solution provided in this application for denitrification treatment of lime kiln flue gas has excellent denitrification performance; it can meet the long-term operation of the denitrification system, and the denitrification efficiency is high when operating continuously for 100 hours.

[0076] By comparing the test results of Examples 1-5 and Comparative Example 1, it can be seen that in Comparative Example 1, when the denitrification efficiency of the SNCR stage was as low as 10%, the content of the injected urea solution was low, resulting in poor subsequent SCR denitrification efficiency. In contrast, in Examples 2-3, 1, and 4, when the denitrification efficiency of the SNCR stage gradually increased from 10% to 30%, the subsequent SCR denitrification efficiency gradually improved; however, in Example 5, when the denitrification efficiency of the SNCR stage was as high as 40%, the content of the injected urea solution was high, and the subsequent SCR denitrification efficiency was not improved. This application selects to control the denitrification efficiency of the SNCR stage to 10%-30%.

[0077] By comparing the test results of Examples 1, 6-14, and Comparative Examples 2-4, it can be seen that the flue gas temperature and space velocity in the SCR furnace in Comparative Example 2 did not meet the limits; zinc-aluminum hydrotalcite was not added to the catalyst in Comparative Example 3; and the dosage of each raw material component in the catalyst in Comparative Example 4 was mismatched, resulting in poor denitrification efficiency. In contrast, the embodiments of this application, by using appropriate flue gas temperature and space velocity in the furnace during the SCR treatment process, adding zinc-aluminum hydrotalcite to the catalyst, and controlling the dosage of each raw material component, significantly improve the denitrification efficiency.

[0078] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for denitrification treatment of flue gas from a lime kiln, characterized in that, Specifically, the following steps are performed sequentially: SNCR processing, SCR processing; The process parameters for the SNCR stage are: flue gas temperature 900-1200℃, injection of 10-14wt% urea solution, and target denitrification efficiency of 10-30%. The formula for calculating the urea solution injection rate is: Urea solution flow rate = Q × C NOx ×η×M 尿素 ×10 -6 / (2×M NO2 ×ρ×X); Wherein, the unit of urea solution flow rate is kg / h; Q: flue gas flow rate, Nm³ / h; C NOx Initial NOx concentration, mg / Nm³, as NO2; η: Target denitrification efficiency; M 尿素 Molar mass of urea, g / mol; M NO2 : Molar mass of NO2, g / mol; ρ: Mass concentration of urea solution; X: Efficiency of urea to NH3 conversion, taken as 0.9; The process parameters for the SCR stage are: flue gas temperature of 180-220℃, 17-22wt% ammonia water as the reducing agent, honeycomb catalyst, and space velocity of 3000-5000 h⁻¹. -1 ; The honeycomb catalyst is prepared from the following components in parts by weight: 3-10 parts vanadium pentoxide, 20-30 parts titanium dioxide, 40-50 parts zinc aluminum hydrotalcite and 1-8 parts stearic acid. The preparation method of the zinc-aluminum hydrotalcite includes the following steps: Under constant temperature water bath, a mixed salt solution of soluble zinc salt and soluble aluminum salt and NaOH alkaline solution are simultaneously added dropwise to the reactor. The pH value of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 50-80℃ for 2-8 hours. After washing, filtering and drying, the solution is obtained. The preparation method of the honeycomb catalyst is as follows: weigh the corresponding weights of each raw material component, mix them evenly, grind them so that the average particle size of the raw material is ≤5μm, add 2-8w / w% oxalic acid to the raw material system, and mix evenly; according to the molding requirements, use an extruder to extrude the mud, and then dry and calcine it to obtain the honeycomb catalyst.

2. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that... The process parameters for the SNCR section are: flue gas temperature 900-1200℃, injection of 10-14wt% urea solution, and target denitrification efficiency of 15-25%.

3. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The process parameters for the SNCR section are: flue gas temperature 900-1200℃, injection of 11-13wt% urea solution, and target denitrification efficiency of 17-22%.

4. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The process parameters for the SCR section are as follows: flue gas temperature 180-220℃; 18-21wt% ammonia water as the reducing agent; outlet pressure 0.9-1.2MPa; and pump flow rate 0.6-0.9m³ / h. 3 The air is pumped to the spray gun at a flow rate of 0.35-0.45 MPa and then atomized by compressed air at the spray gun inlet before being sprayed into the ammonia evaporator; the air velocity is 3500-4500 h⁻¹. -1 .

5. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The honeycomb catalyst is prepared from the following components in parts by weight: 5-8 parts vanadium pentoxide, 22-28 parts titanium dioxide, 42-48 parts zinc aluminum hydrotalcite and 3-6 parts stearic acid. The titanium dioxide has a particle size of 50-150 nm.

6. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The preparation method of the zinc-aluminum hydrotalcite specifically includes the following steps: In a constant temperature water bath at 40-70℃, a mixed salt solution containing 0.6-1.0 mol / L soluble zinc salt and 0.1-0.3 mol / L soluble aluminum salt, and a NaOH alkaline solution at 0.8-1.2 mol / L are simultaneously added dropwise to a reactor. The pH of the reaction solution is maintained between 9 and 10. After stirring and mixing evenly, the solution is crystallized at 50-80℃ for 2-8 hours. After washing, filtering, and drying, the product is obtained.

7. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, In the preparation method of the honeycomb catalyst, the drying conditions are: temperature 60-80℃, time 12-24h; the calcination conditions are: heating to 500-600℃ at a rate of 3-10℃ / min, and holding at that temperature for 3-5h.

8. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The specifications of the honeycomb catalyst are as follows: 30×30 pores, pore diameter of 4-8 mm, and wall thickness of 0.8-1.2 mm.

9. The method for denitrification of lime kiln flue gas according to claim 1, characterized in that, The lime kiln flue gas denitrification treatment method utilizes a lime kiln flue gas denitrification system for denitrification treatment, which includes an SNCR reaction section, an SCR reaction section, and a chimney connected in sequence. The SNCR section is located in the kiln tail flue and is equipped with ultrasonic atomizing nozzles; the SCR section adopts a modular catalyst bed and has an ash hopper at the bottom.

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