A denitration system for adding pure ammonia gas to high nitrogen oxide concentration flue gas

Abstract

The utility model belongs to the field of flue gas denitration, especially is involved in a kind of denitration system for adding pure ammonia gas to high nitrogen oxide concentration flue gas. In order to realize emission reduction, the utility model provides a kind of denitration system for adding pure ammonia gas to high nitrogen oxide concentration flue gas, the denitration system includes flue, denitration reactor, flue gas on-line monitor, pure ammonia gas adding system for adding pure ammonia gas to flue and automatic control system;Pure ammonia gas adding system includes the ammonia supply line for conveying pure ammonia gas, flow regulating valve and ammonia gas flowmeter are equipped on ammonia supply line, the downstream end of ammonia supply line is equipped with pure ammonia nozzle located in flue and located in the downstream of flue gas on-line monitor;Automatic control system is used to control the opening of flow regulating valve according to the flow and nitrogen oxide concentration of original flue gas. Directly add pure ammonia gas to original flue gas, and dilute pure ammonia gas using original flue gas, thereby saving the energy consumed by dilution fan and reducing the amount of flue gas finally discharged.

Description

Technical Field

[0001] This utility model belongs to the field of flue gas denitrification, and in particular relates to a denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration. Background Technology

[0002] like Figure 1 As shown, in industrial flue gas denitrification processes, ammonia water, urea solution, or ammonia gas needs to be added as a denitrification reducing agent to reduce nitrogen oxides (NOx). x For the removal of NO, the conventional method when using ammonia gas is to dilute the ammonia concentration to about 5% using a dilution fan 1 and a static mixer 2 (also known as an ammonia / air mixer) before introducing it into the flue gas 4. The diluted ammonia gas is then mixed with the original flue gas and enters the denitrification reactor 5 for NO removal. x The removal reaction.

[0003] It is important to note that a PID automatic control system is needed to control the ammonia dosage when adding the reducing agent (refer to Chinese invention patent application CN116272360A, published on June 23, 2023). If the ammonia dosage is too high, serious ammonia escape will occur, increasing costs and causing excess ammonia to react with flue gas to produce ammonium bisulfate, clogging flue ducts and subsequent treatment equipment. If the ammonia dosage is too low, the denitrification task will not be completed, leading to NO3-20% emissions. x Emissions exceeded standards and did not meet environmental protection requirements.

[0004] The above-mentioned process originated from the SCR (Selective Catalytic Reduction) denitrification process in coal-fired power plants. Its characteristics include: a relatively large raw flue gas volume (the volume of flue gas before mixing with ammonia) (generally one to several million standard cubic meters per hour), a large flue gas duct cross-section, but a relatively low initial NO content in the raw flue gas. x The concentration is not high (usually below 1500 mg / Nm³). 3 Furthermore, the SCR is located close to the boiler, and the unburned coal powder or coal particles in the original flue gas may carry open flames. The ammonia injection point is very close to the SCR reactor (i.e., denitrification reactor 5), and the mixing distance between the flue gas and ammonia is very short.

[0005] Under the above operating conditions, it is necessary to dilute the ammonia with air. Its function is to reduce the ammonia concentration to below the explosive concentration. Moreover, the diluted ammonia is injected into the flue gas 4 through the ammonia injection grid 3, which is more conducive to the uniform mixing of ammonia with the original flue gas as much as possible when the cross-section of the flue gas 4 is large and the mixing distance is short.

[0006] To facilitate understanding by those skilled in the art, two patent documents using diluted ammonia as a reducing agent are presented below.

[0007] (1) Chinese invention patent application with publication number CN114699889A and publication date of July 5, 2022, in which pure ammonia and dilution air are mixed by a gas mixer and diluted to a volume percentage of ammonia of less than 5%.

[0008] (2) Chinese invention patent with authorization announcement number CN109173635B and authorization announcement date of March 26, 2024. In this patent, the ammonia supply pipeline includes a pure ammonia branch pipe and a dilution air duct. Pure ammonia gas (NH3) is injected into the dilution air duct through a pure ammonia nozzle arranged on the pure ammonia branch pipe, thereby mixing the pure ammonia gas with air and using the mixed gas as a reducing agent.

[0009] It should be noted that, in this field, ammonia generally refers to a mixture of pure ammonia and air, that is, ammonia includes both pure ammonia and air.

[0010] When processing industrial flue gas from factories other than coal-fired power plants, the following operating conditions exist: the raw flue gas volume is low (less than 500,000 standard cubic meters per hour), but the initial NO content of the raw flue gas is high. x The concentration is relatively high.

[0011] The original flue gas volume was low, but the initial NO x Under conditions of high concentration, if ammonia gas with a concentration of less than 5% is still used as a reducing agent, the proportion of dilution air volume to the original flue gas volume will be relatively large, which will lead to the following problems: (1) The dilution air volume is large, and the power of the dilution fan is relatively large, which wastes energy; (2) The reaction temperature of the denitrification reactor is generally between 280 ℃ and 420 ℃. Within this temperature range, the catalyst has good activity. However, due to the low temperature and large volume of dilution air, the temperature of the flue gas in the denitrification reactor is low. This affects the activity of the catalyst, resulting in low denitrification efficiency and consequently, a decrease in NO content in the treated flue gas. x The high concentration is detrimental to environmental protection; on the other hand, the low temperature of the subsequent flue gas is not conducive to the subsequent utilization of waste heat. (3) The ratio of dilution air volume to original flue gas volume is relatively large, resulting in a significantly larger flow rate of flue gas after the dilution air, ammonia and original flue gas are mixed, which significantly increases the flue gas volume, increases the burden on flue gas treatment equipment, and the power of the main induced draft fan also needs to be increased accordingly, wasting energy. (4) The dilution air volume is relatively large compared with the original flue gas volume, which leads to a significant increase in the oxygen content of the mixed flue gas and a large amount of pollutant emissions after conversion, which is not conducive to environmental protection. Utility Model Content

[0012] The purpose of this invention is to provide a denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentrations, in order to solve the problem of low initial flue gas volume but high initial NO content. x Under high concentration conditions, the existing SCR denitrification process faces technical challenges in energy conservation and emission reduction.

[0013] To achieve the above objectives, the technical solution provided by this utility model for a denitrification system that adds pure ammonia to flue gas with high nitrogen oxide concentrations is as follows: A denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration includes a flue and a denitrification reactor connected to the flue, and also includes an online flue gas monitor for monitoring the flow rate and nitrogen oxide concentration of the original flue gas in the flue, a pure ammonia addition system for adding pure ammonia to the flue, and an automatic control system. The pure ammonia dosing system includes an ammonia supply pipeline for conveying pure ammonia, a flow regulating valve and an ammonia flow meter on the ammonia supply pipeline, and a pure ammonia nozzle located in the flue at the downstream end of the ammonia supply pipeline, and the pure ammonia nozzle is located downstream of the flue gas online monitoring instrument. The automatic control system is used to control the opening degree of the flow regulating valve according to the flow rate and nitrogen oxide concentration of the raw flue gas; The denitrification reactor is located downstream of the flue gas online monitoring instrument and the pure ammonia nozzle.

[0014] Furthermore, an emergency shut-off valve is installed on the ammonia supply pipeline, and the flue gas online monitoring instrument is used to monitor the flue gas temperature. The automatic control system is used to control the emergency shut-off valve to close when the flue gas flow rate is too low or the flue gas temperature is abnormal.

[0015] Furthermore, the ammonia supply pipeline is also connected to a purging pipeline, and the connection point between the purging pipeline and the ammonia supply pipeline is located downstream of the emergency shut-off valve; the purging pipeline is equipped with a purging valve for controlling the on / off state of the purging pipeline.

[0016] Furthermore, the end of the purging line furthest from the ammonia supply line is connected to a nitrogen cylinder or nitrogen port.

[0017] Furthermore, a mixer is installed on the flue between the pure ammonia nozzle and the denitrification device.

[0018] Furthermore, a spray gun fixed on the flue is connected to the downstream end of the ammonia supply pipeline, and the nozzle of the spray gun constitutes the pure ammonia nozzle.

[0019] Furthermore, the ammonia supply pipeline is equipped with a thermometer for monitoring the temperature of pure ammonia gas and a pressure gauge for monitoring the pressure of pure ammonia gas.

[0020] Furthermore, multiple pure ammonia nozzles are arranged at intervals within the flue.

[0021] Furthermore, a check valve is also installed on the ammonia supply pipeline, located downstream of the flow regulating valve and the ammonia flow meter.

[0022] Furthermore, a filter is installed on the ammonia supply line, located upstream of the flow regulating valve and the ammonia flow meter.

[0023] The beneficial effects of the denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration provided by this utility model are as follows: This utility model is an improved invention. In this utility model, the dilution fan and static mixer are eliminated. By directly adding pure ammonia to the original flue gas, there is no need to introduce dilution air, which can effectively reduce the flue gas volume and save the energy consumed by the dilution fan, thus contributing to energy conservation and emission reduction.

[0024] To facilitate understanding by those skilled in the art, the following description, in conjunction with specific usage scenarios, explains the beneficial effects of this utility model's denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentrations.

[0025] In use, firstly, the flue gas online monitoring instrument can monitor the flow rate and nitrogen oxide concentration of the raw flue gas in real time. The automatic control system determines the dosage of pure ammonia based on the above data and controls the dosage of pure ammonia by controlling the opening of the flow regulating valve and monitoring the data of the ammonia flow meter. Then, pure ammonia is sprayed from the pure ammonia nozzle into the flue and mixed with the raw flue gas in the flue. Finally, the mixed flue gas enters the denitrification reactor to complete the denitrification.

[0026] The purpose of controlling the amount of pure ammonia added is to ensure a suitable flue gas temperature and to ensure that the majority of NO in the flue gas is within acceptable limits. x It can react with pure ammonia to produce nitrogen and water.

[0027] Based on the above usage, it is clear that in this invention, there is no need to install a dilution fan to introduce dilution air, therefore this invention has the following beneficial effects: (1) Saves on dilution fans and energy; (2) Without diluting the air to lower the temperature of the flue gas, the flue gas temperature is relatively high. On the one hand, the catalyst activity is better and the denitrification efficiency is high; on the other hand, it is conducive to the subsequent utilization of waste heat. (3) The flue gas does not include dilution air, so the flue gas volume is small, which can reduce the burden on the flue gas treatment equipment, and the power of the main induced draft fan can be reduced accordingly, saving energy; (4) Since the flue gas does not include dilution air, the oxygen content in the flue gas is low, and the amount of pollutants emitted after conversion is small, which is beneficial to environmental protection. Attached Figure Description

[0028] Figure 1 A schematic diagram of the ammonia dosing system in an existing industrial flue gas denitrification process; Figure 2 This is a schematic diagram of the denitrification system of this invention, which involves adding pure ammonia to flue gas with high nitrogen oxide concentrations.

[0029] Explanation of reference numerals in the attached figures: Figure 1 The components are: 1. Dilution fan; 2. Static mixer; 3. Ammonia injection grid; 4. Flue; 5. Denitrification reactor.

[0030] Figure 2 The components include: 1. Manual control valve; 2. Pressure gauge; 3. Temperature gauge; 4. Pressure transmitter; 5. Purge valve; 6. Ammonia flow meter; 7. Flow regulating valve; 8. Maintenance valve; 9. Ammonia alarm; 10. Check valve; 11. Filter; 12. Emergency shut-off valve; 13. Nitrogen cylinder; 14. Bypass valve; 15. Drain valve; 16. Online flue gas monitor; 17. Flue; 18. Spray gun; 19. Mixer; 20. Denitrification reactor. Detailed Implementation

[0031] In this invention, the gas not mixed with ammonia is called raw flue gas, and the gas after mixing raw flue gas with ammonia is called flue gas.

[0032] To address the problems in the background technology, the core inventive concept of this utility model is: to directly add pure ammonia gas into the original flue gas according to the original flue gas flow rate, and to use the original flue gas to dilute the pure ammonia gas, thereby reducing the final amount of flue gas emitted.

[0033] The present invention will be further described in detail below with reference to the embodiments.

[0034] like Figure 2 As shown, the denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration includes a flue 17, a denitrification reactor 20 connected to the flue 17, an online flue gas monitor 16 for monitoring the flow rate, flue gas temperature, and nitrogen oxide concentration of the original flue gas in the flue 17, a pure ammonia dosing system for adding pure ammonia to the flue 17, and an automatic control system. The denitrification reactor 20 is located downstream of the online flue gas monitor 16 and the pure ammonia nozzle. The pure ammonia dosing system includes an ammonia supply pipeline for conveying pure ammonia, on which a flow regulating valve 7 and an ammonia flow meter 6 are installed. A pure ammonia nozzle is located in the flue 17 at the downstream end of the ammonia supply pipeline, and the pure ammonia nozzle is located downstream of the online flue gas monitor 16. The automatic control system controls the opening degree of the flow regulating valve 7 according to the flow rate and nitrogen oxide concentration of the original flue gas.

[0035] Among them, the denitrification reactor 20, flow regulating valve 7, ammonia flow meter 6 and flue gas online monitoring instrument 16 (CEMS) are existing products; the automatic control system adopts PID automatic control system; the downstream end of the ammonia supply pipeline is connected to a spray gun 18 fixed on the flue 17 by welding or other means, and the nozzle of the spray gun 18 constitutes the pure ammonia nozzle. Of course, the structure of the pure ammonia nozzle can also be the same as the structure of the pure ammonia nozzle in the Chinese invention patent with authorization announcement number CN109173635B mentioned in the background art. However, the pure ammonia nozzle in this utility model is set in the flue 17 to directly spray pure ammonia into the original flue gas.

[0036] The core difference between this invention and the prior art is that in this invention, pure ammonia is directly added to the original flue gas, resulting in a small total flue gas emission; while in the prior art, pure ammonia is first diluted with dilution air to obtain a 5% concentration of ammonia, and then the 5% concentration of ammonia is added to the original flue gas, resulting in a large total flue gas emission.

[0037] In use, firstly, the flue gas online monitoring instrument 16 can monitor the flow rate and nitrogen oxide concentration of the raw flue gas in real time. The automatic control system determines the dosage of pure ammonia gas based on the above data and controls the dosage of pure ammonia gas by controlling the opening of the flow regulating valve 7 and monitoring the data of the ammonia gas flow meter 6. Then, pure ammonia gas is sprayed from the pure ammonia nozzle into the flue duct 17 and mixed with the raw flue gas in the flue duct 17. Finally, the mixed flue gas enters the denitrification reactor 20 to complete the denitrification.

[0038] The purpose of controlling the amount of pure ammonia added is to ensure a suitable flue gas temperature and to ensure that the majority of NO in the flue gas is within acceptable limits. x It can react with pure ammonia to produce nitrogen and water.

[0039] The ammonia injection rate is calculated based on parameters such as the original flue gas volume, the nitrogen oxide concentration in the original flue gas, and the nitrogen oxide concentration in the permissible emission gas. It is controlled by a PID automatic control system and tracked by an ammonia flow meter 6.

[0040] The ammonia supply pipeline is equipped with a thermometer 3 for monitoring the temperature of pure ammonia, a pressure gauge 2 for monitoring the pressure of pure ammonia, and a pressure transmitter 4 for monitoring the pressure of pure ammonia, so as to obtain the temperature and pressure of pure ammonia; or, an ammonia cylinder is connected upstream of the ammonia supply pipeline, the ammonia cylinder including a cylinder body and a temperature transmitter and a pressure transmitter installed at the cylinder mouth, so as to obtain the temperature and pressure of pure ammonia.

[0041] Based on the above usage, it is clear that in this invention, there is no need to install a dilution fan to introduce dilution air, therefore this invention has the following beneficial effects: (1) Saves on dilution fans and energy; (2) Without diluting the air to lower the temperature of the flue gas, the flue gas temperature is relatively high. On the one hand, the catalyst activity is better and the denitrification efficiency is high; on the other hand, it is conducive to the subsequent utilization of waste heat. (3) The flue gas does not include dilution air, so the flue gas volume is small, which can reduce the burden on the flue gas treatment equipment, and the power of the main induced draft fan can be reduced accordingly, saving energy; (4) Since the flue gas does not include dilution air, the oxygen content in the flue gas is low, and the amount of pollutants emitted after conversion is small, which is beneficial to environmental protection.

[0042] To enhance safety, in a preferred embodiment, an emergency shut-off valve 12 is also provided on the ammonia supply pipeline. The emergency shut-off valve 12 is an existing product, and the automatic control system is used to control the emergency shut-off valve 12 to close when the original flue gas flow is too low or the flue gas temperature is abnormal, so as to ensure that no safety accidents occur.

[0043] Those skilled in the art can set the corresponding minimum flow rate and abnormal smoke temperature value according to the actual situation. No limitation is made here. The minimum flow rate and abnormal smoke temperature value will also be different depending on the actual working conditions. Those skilled in the art can set them reasonably according to the project parameter requirements.

[0044] In a preferred embodiment, the ammonia supply pipeline is also connected to a purging pipeline, and the connection between the purging pipeline and the ammonia supply pipeline is located downstream of the emergency shut-off valve 12; the purging pipeline is equipped with a purging valve 5 for controlling the opening and closing of the purging pipeline; the end of the purging pipeline away from the ammonia supply pipeline is connected to a nitrogen cylinder 13 or an air compressor, so as to use high-pressure nitrogen or compressed air to purge the ammonia supply pipeline downstream of the emergency shut-off valve 12 to avoid blockage of the ammonia supply pipeline.

[0045] The control air source for the emergency shut-off valve 12 can be high-pressure nitrogen or compressed air; similarly, the control air source for the flow regulating valve 7 can also be high-pressure nitrogen or compressed air.

[0046] In other embodiments, the end of the purging line away from the ammonia supply line is connected to a nitrogen interface, which is a common quick-connect interface in the art, allowing for quick connection to equipment such as nitrogen cylinder 13 or air compressor.

[0047] exist Figure 2 In the embodiment shown, the emergency shut-off valve 12 is located upstream of the ammonia flow meter 6 and the flow regulating valve 7. The connection between the purging pipeline and the ammonia supply pipeline is also located upstream of the ammonia flow meter 6 and the flow regulating valve 7. Downstream of the ammonia flow meter 6 and the flow regulating valve 7, there are a drain valve 15 and a maintenance valve 8 arranged in parallel.

[0048] When the emergency shut-off valve 12 and the maintenance valve 8 are closed, the drain valve 15 is opened, and the purging gas (high-pressure nitrogen or compressed air) can blow away the dirt in the ammonia flow meter 6 and the flow regulating valve 7 through the drain valve 15.

[0049] exist Figure 2 In the embodiment shown, another maintenance valve 8 is provided upstream of the emergency shut-off valve 12. The pipeline between the two maintenance valves 8 is connected in parallel with the bypass pipeline, and a bypass valve 14 is provided on the bypass pipeline.

[0050] Normally, bypass valve 14 is always closed to control the ammonia injection rate via ammonia flow meter 6 and flow regulating valve 7. If ammonia flow meter 6 or flow regulating valve 7 malfunctions, requiring maintenance of the pipeline between the two maintenance valves 8, both maintenance valves 8 are closed, and bypass valve 14 is opened to temporarily introduce pure ammonia into the flue gas. Workers manually control the opening of bypass valve 14 to regulate the ammonia injection rate. However, because the ammonia injection rate is not under real-time control by the automatic control system, ammonia escape or insufficient ammonia injection to complete the denitrification task can easily occur. Therefore, rapid maintenance is necessary.

[0051] Of course, in other preferred embodiments, the pipeline between the two maintenance valves 8 is defined as an ammonia supply branch. Then, there can also be two ammonia supply branches in parallel. When a failure occurs in one ammonia supply branch, the maintenance valve 8 in that ammonia supply branch is closed, and the maintenance valve 8 in the other ammonia supply branch is opened, so that the other ammonia supply branch can be used for quantitative ammonia supply.

[0052] To improve the mixing efficiency of pure ammonia and raw flue gas, in a preferred embodiment, a mixer 19 is also installed on the flue 17 between the pure ammonia nozzle and the denitrification device. The mixer 19 is an existing product, and its function is to mix the gases evenly. It is commonly used for mixing fuel gas with air (oxygen).

[0053] In this invention, based on the cross-sectional area of ​​the flue 17 (i.e., the flow area of ​​the flue 17), those skilled in the art can adaptably arrange one, two, three, or more pure ammonia nozzles within the flue 17. With a fixed ammonia dosage, the more pure ammonia nozzles there are, the larger the contact area between the pure ammonia gas and the original flue gas, resulting in a better mixing effect.

[0054] In a preferred embodiment, a check valve 10 or a check valve is also provided on the ammonia supply pipeline. The check valve 10 (check valve) is located downstream of the flow regulating valve 7 and the ammonia flow meter 6 to prevent gas backflow.

[0055] In other embodiments, the flow regulating valve 7 can also be a one-way flow regulating valve, that is, the flow regulating valve 7 has a built-in one-way valve function; or, the pressure of pure ammonia gas can be made greater than the pressure of the original flue gas.

[0056] In actual production, the entire denitrification system will have a main induced draft fan to make the flue gas flow quickly in the flue 17. Under the action of the main induced draft fan, the flue 17 is generally under negative pressure, and the ammonia supply pipeline is generally under positive pressure. Unless the flue 17 is blocked, the flue gas will not flow back into the ammonia supply pipeline.

[0057] In a preferred embodiment, a filter 11 is also provided on the ammonia supply pipeline. The filter 11 is located upstream of the flow regulating valve 7 and the ammonia flow meter 6 to filter impurities in the pure ammonia gas.

[0058] In other embodiments, the ammonia cylinder may also have its own filter (i.e., the ammonia cylinder includes a cylinder body and a filter installed at the cylinder opening), and the ammonia pipeline can be connected to the filter.

[0059] exist Figure 2 In the embodiment shown, a manual control valve 1 is also provided at the upstream end of the ammonia supply pipeline, which can be manually shut off in case the automatic control system fails; an ammonia alarm 9 is also provided around the ammonia supply pipeline, which is used to alarm when ammonia leaks, so as to notify maintenance personnel to quickly repair the ammonia supply pipeline.

[0060] Finally, it should be noted that the above are merely preferred embodiments of this utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features, or organically combine different embodiments to create the embodiments shown in the accompanying drawings. Of course, those skilled in the art can also create other embodiments not shown in the accompanying drawings. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration, comprising a flue and a denitrification reactor connected to the flue, characterized in that, It also includes an online flue gas monitoring instrument for monitoring the flow rate and nitrogen oxide concentration of the raw flue gas in the flue, a pure ammonia dosing system for adding pure ammonia into the flue, and an automatic control system; The pure ammonia dosing system includes an ammonia supply pipeline for conveying pure ammonia, a flow regulating valve and an ammonia flow meter on the ammonia supply pipeline, and a pure ammonia nozzle located in the flue at the downstream end of the ammonia supply pipeline, and the pure ammonia nozzle is located downstream of the flue gas online monitoring instrument. The automatic control system is used to control the opening degree of the flow regulating valve according to the flow rate and nitrogen oxide concentration of the raw flue gas; The denitrification reactor is located downstream of the flue gas online monitoring instrument and the pure ammonia nozzle.

2. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in claim 1, characterized in that, An emergency shut-off valve is also installed on the ammonia supply pipeline. The flue gas online monitoring instrument is used to monitor the flue gas temperature. The automatic control system is used to control the emergency shut-off valve to close when the flue gas flow rate is too low or the flue gas temperature is abnormal.

3. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in claim 2, characterized in that, The ammonia supply pipeline is also connected to a purging pipeline, and the connection between the purging pipeline and the ammonia supply pipeline is located downstream of the emergency shut-off valve; the purging pipeline is equipped with a purging valve for controlling the opening and closing of the purging pipeline.

4. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in claim 3, characterized in that, The end of the purging line furthest from the ammonia supply line is connected to a nitrogen cylinder or nitrogen port.

5. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, A mixer is also installed on the flue between the pure ammonia nozzle and the denitrification device.

6. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, The downstream end of the ammonia supply pipeline is connected to a spray gun fixed on the flue, and the nozzle of the spray gun constitutes the pure ammonia nozzle.

7. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, The ammonia supply pipeline is equipped with a thermometer for monitoring the temperature of pure ammonia gas and a pressure gauge for monitoring the pressure of pure ammonia gas.

8. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, Multiple pure ammonia nozzles are arranged at intervals within the flue.

9. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, A check valve is also installed on the ammonia supply pipeline. The check valve is located downstream of the flow regulating valve and the ammonia flow meter.

10. The denitrification system for adding pure ammonia to flue gas with high nitrogen oxide concentration as described in any one of claims 1 to 4, characterized in that, A filter is also installed on the ammonia supply pipeline, located upstream of the flow regulating valve and the ammonia flow meter.

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