A device for flue gas denitrification to prevent ammonia escape

Abstract

This invention relates to the field of flue gas purification technology and discloses a device for preventing ammonia escape during flue gas denitrification. The device includes a denitrification reactor, a flue gas duct on the left side of the reactor's exterior, and a flue gas channel, an ammonia mixing zone, and a catalyst layer arranged sequentially from top to bottom inside the reactor. An ammonia injection grid is installed in the flue gas channel, and multiple nozzles are mounted on the grid. A purified flue gas duct is located on the right side of the reactor's exterior, with a tail gas outlet at its end. A denitrification outlet monitoring probe is installed on the tail gas outlet. Each nozzle includes a reducing agent solution pipe, a compressed air pipe, and a protective sleeve. The reducing agent solution pipe is located inside the compressed air pipe, which is also located inside the protective sleeve. This structure ensures that the stable flue gas and premixed reducing agent can be uniformly and fully mixed in the ammonia mixing zone, further improving the overall denitrification reaction efficiency of the device.

Description

Technical Field

[0001] This invention relates to the field of flue gas purification technology, specifically to a device for flue gas denitrification to prevent ammonia escape. Background Technology

[0002] SCR (Selective Catalytic Reduction) flue gas denitrification technology has been widely used in the flue gas treatment process of coal-fired, gas-fired, and waste incineration boilers. The basic principle of this technology is to inject ammonia or ammonia water, or other reducing agents, into the flue gas. Under the action of a catalyst, the reducing agent reacts with the nitrogen oxides (NOx) in the flue gas to produce harmless nitrogen (N2) and water (H2O), thereby purifying the flue gas.

[0003] However, existing denitrification systems suffer from several structural and control defects in actual operation. Limited by the traditional ammonia injection grid structure and the airflow distribution within the flue, the raw flue gas entering the reactor is prone to flow deviation and eddies, resulting in uneven mixing of the flue gas and the injected ammonia. This uneven mixing leads to incomplete reaction at the catalyst bed cross-section. To maintain overall denitrification efficiency, the amount of reducing agent injected is usually increased during operation, resulting in severe ammonia excess in localized areas. This localized excess ammonia cannot fully participate in the reduction reaction and is discharged from the system with the clean flue gas, directly causing an increase in ammonia slip rate.

[0004] Ammonia escape not only wastes reducing agent and increases system operating costs, but also causes serious secondary hazards. Escaping ammonia readily reacts with acidic components in the downstream flue gas, forming ammonium salt crystals such as ammonium bisulfate. These ammonium salts are highly adhesive and corrosive, adhering to and clogging catalyst channels, air preheaters, and downstream dust removal equipment. They also exacerbate corrosion of the metal flue gas, increasing system operating resistance and severely shortening the service life of related equipment and catalysts.

[0005] Furthermore, current denitrification systems generally lack real-time, multi-point monitoring methods for ammonia slip at the outlet section of the denitrification reactor. Moreover, the monitoring system is independent of the upstream ammonia injection device, failing to establish a coordinated control mechanism. When localized ammonia slip exceeds the limit, the control system cannot obtain accurate cross-sectional concentration feedback, thus hindering targeted flow correction for each zone of the ammonia injection grid. This crude operating mode, lacking closed-loop intelligent regulation, prevents existing denitrification devices from accurately controlling the ammonia injection rate in each area, making it difficult to fundamentally solve the problems of excessive ammonia slip and the resulting equipment blockage and corrosion. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a device for preventing ammonia escape in flue gas denitrification. This device solves the problem that existing SCR denitrification devices suffer from uneven mixing of flue gas and reducing agent, as well as the lack of a real-time monitoring and linkage adjustment mechanism, which leads to excessive ammonia in some areas, causing ammonia escape exceeding the standard, and consequently resulting in ammonium salt blockage and corrosion in downstream equipment, as well as high operating costs.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A device for preventing ammonia escape during flue gas denitrification includes a denitrification reactor. A flue gas duct is provided on the left side of the outside of the denitrification reactor. Inside the denitrification reactor, from top to bottom, there are a flue gas channel, an ammonia mixing zone, and a catalyst layer. An ammonia injection grid is installed in the flue gas channel, and multiple nozzles are installed on the ammonia injection grid. A purified flue gas duct is provided on the right side of the outside of the denitrification reactor. A tail gas emission port is provided at the end of the purified flue gas duct, and a denitrification outlet monitoring probe is installed on the tail gas emission port.

[0009] Preferably, the nozzle includes a reducing agent solution pipe, a compressed air pipe, and a protective sleeve, wherein the reducing agent solution pipe is disposed inside the compressed air pipe, and the compressed air pipe is disposed inside the protective sleeve.

[0010] Preferably, a reducing agent solution inlet is installed at one end of the reducing agent solution pipeline, and a mechanical conical atomizing nozzle is installed at the other end. A swirl vane is installed inside the reducing agent solution pipeline.

[0011] Preferably, a compressed air inlet is installed at one end of the compressed air pipeline, and a fan-shaped air atomizing nozzle is installed at the other end.

[0012] Preferably, a soot blowing cooling air inlet is installed on the side wall of the protective sleeve, and quick-connect flanges are installed on both sides of the outer side of the protective sleeve.

[0013] Preferably, a jet mixer is installed on the left side outside the flue gas duct, a dilution fan is installed on the left side outside the jet mixer, a flue gas denitrification device is installed on the left side outside the dilution fan, and an ammonia water evaporator is installed outside the flue gas denitrification device.

[0014] Preferably, the device further includes a static mixer, which has cross-distributed swirl blades installed inside. One end of the static mixer is provided with a mixed gas inlet, and the other end is provided with a mixed gas nozzle.

[0015] Preferably, the external part of the denitrification outlet monitoring probe is equipped with a laser emitting end, and multiple distributed sensors are installed on one side of the external part of the denitrification outlet monitoring probe.

[0016] Preferably, the device is also equipped with a PLC controller and an electric regulating valve. The electric regulating valve is installed on the ammonia injection grid, and the denitrification outlet monitoring probe, PLC controller and electric regulating valve are electrically connected.

[0017] The ammonia injection grille is set up in multiple independent zones, and the flue gas duct above the flue gas passage is equipped with multi-layer rectifier distribution plates.

[0018] This invention provides a device for flue gas denitrification to prevent ammonia escape. It has the following beneficial effects:

[0019] 1. This invention constructs a monitoring network spanning the entire cross-section of the denitrification outlet by coordinating a monitoring probe at the denitrification outlet, a laser emitter, and multiple distributed sensors. The real-time ammonia concentration data collected from each zone is fed back to a PLC controller. After calculation, the PLC controller controls the electric regulating valves installed on the zoned ammonia injection grids, enabling real-time correction of the ammonia injection amount for each zone and achieving uniform ammonia injection across the entire cross-section. This closed-loop regulation structure eliminates localized ammonia excess, preventing ammonia escape from the source and reducing the system's reducing agent consumption and operating costs.

[0020] 2. The nozzle in this invention adopts a nested coaxial structure consisting of a reducing agent solution pipeline, a compressed air pipeline, and a protective sleeve. After the reducing agent solution undergoes rotation and primary atomization by the swirl vanes and the mechanical conical atomizing nozzle, a second pneumatic shearing is performed using high-speed compressed air ejected from the fan-shaped air atomizing nozzle, achieving fine atomization of the reducing agent and increasing the gas-liquid contact area. Furthermore, the protective sleeve introduces cooling air to form an air film, cooling and purging the atomizing components to prevent escaping ammonia gas from forming ammonium salt crystals at the front end, causing blockage or corrosion, and extending the service life of the equipment and catalyst layer.

[0021] 3. This invention incorporates a static mixer with cross-distributed swirl blades in the reducing agent pretreatment link. Utilizing the dual mixing effects of spatial deflection and forced rotation, it ensures that ammonia and air reach a highly uniform state before being injected into the reactor. Simultaneously, multiple layers of rectifying and distributing plates are installed inside the flue gas duct to distribute and streamline the incoming flue gas, eliminating flue gas deviation and eddy current phenomena. This dual flow equalization structure guarantees that the stable flue gas and premixed reducing agent can be uniformly and fully mixed within the ammonia mixing zone, further improving the overall denitrification reaction efficiency of the device. Attached Figure Description

[0022] Figure 1 This is a perspective view of the present invention;

[0023] Figure 2 A schematic diagram illustrating the nozzle structure of the present invention is provided.

[0024] Figure 3 To highlight the schematic diagram of the reducing agent solution pipeline structure of the present invention;

[0025] Figure 4 A schematic diagram of the static mixer structure of the present invention is provided to highlight the present invention;

[0026] Figure 5 A schematic diagram of the structure of the denitrification export monitoring probe of the present invention is shown.

[0027] The components include: 1. Ammonia evaporator; 2. Flue gas denitrification unit; 3. Dilution fan; 4. Injection mixer; 5. Flue gas duct; 6. Denitrification reactor; 7. Purified flue gas duct; 8. Tail gas outlet; 9. Nozzle; 10. Ammonia injection grid; 11. Catalyst layer; 12. Flue gas passage; 13. Ammonia mixing zone; 14. Fan-shaped air atomizing nozzle; 15. Compressed air duct; 16. Swirl vane; 17. Mechanical cone atomizing nozzle; 18. Reducing agent solution duct; 19. Protective sleeve; 20. Quick-connect flange; 21. Reducing agent solution inlet; 22. Compressed air inlet; 23. Soot blowing and cooling air inlet; 24. Static mixer; 25. Mixed gas inlet; 26. Mixed gas nozzle; 27. Multi-point distributed sensor; 28. Denitrification outlet monitoring probe; 29. ​​Laser emitter. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example:

[0030] Please see the appendix Figure 1 - Appendix Figure 5This invention provides a device for preventing ammonia escape during flue gas denitrification, comprising a denitrification reactor 6. A flue gas duct 5 is located on the left side of the reactor 6, serving as the initial channel for the raw flue gas. Inside the reactor 6, from top to bottom, are a flue gas channel 12, an ammonia mixing zone 13, and a catalyst layer 11. The flue gas channel 12 serves as the initial contact area between the raw flue gas and the reducing agent. This area has sufficient height to ensure adequate residence time for the raw flue gas as it flows downwards, and its inner wall is treated with a high-temperature resistant and corrosion-resistant coating to withstand flue gas scouring, providing a foundation for subsequent reactions. The ammonia mixing zone 13 is used to accommodate and buffer the airflow to eliminate defects such as uneven mixing and incomplete reaction. This zone has no other obstructive structures, presenting a spacious cavity state, allowing the downward flow... The moving flue gas stream and the injected reducing agent stream mix in this space. The catalyst layer 11 at the bottom is the working area that promotes the reduction reaction of NOx and ammonia to generate N2 and H2O. When the ammonia-containing flue gas passes through the fine pores inside the catalyst layer 11, a denitrification reaction occurs, ensuring a denitrification efficiency of ≥90% and making NOx emissions meet the standards. An ammonia injection grid 10 is installed in the flue gas channel 12. Multiple nozzles 9 are installed on the ammonia injection grid 10. The ammonia injection grid 10 and the multiple nozzles 9 together constitute the ammonia injection structure of the device. The multiple nozzles 9 are symmetrically arranged on the ammonia injection grid 10 to achieve uniform coverage by matching the cross section. A purified flue gas pipe 7 is set on the right side of the outside of the denitrification reactor 6. A tail gas emission port 8 is set at the end of the purified flue gas pipe 7. A denitrification outlet monitoring probe 28 is installed on the tail gas emission port 8.

[0031] The nozzle 9 includes a reducing agent solution pipe 18, a compressed air pipe 15, and a protective sleeve 19. The reducing agent solution pipe 18 is located inside the compressed air pipe 15, and the compressed air pipe 15 is located inside the protective sleeve 19. The nozzle 9 serves as a structure for injecting the reducing agent into the flue gas channel 12. Its main body includes the reducing agent solution pipe 18, the compressed air pipe 15, and the protective sleeve 19. The reducing agent solution pipe 18 is located at the very center and is located inside the compressed air pipe 15. A first annular gap is left between the pipe walls of the reducing agent solution pipe 18 and the compressed air pipe 15 as a passage for compressed air. The compressed air pipe 15 is further located inside the protective sleeve 19, and a second annular gap is left between the pipe walls of the compressed air pipe 15 and the protective sleeve 19 as a passage for cooling and purging gas. These three layers of pipes are sequentially wrapped from the inside out along the same central axis, forming a nested coaxial structure of the nozzle 9. This structure ensures that the reducing agent, compressed air, and cooling gas can be independently transported along their respective channels inside the nozzle 9. At the output end, this structure can cause the centrally ejected reducing agent liquid flow and the compressed air surrounding it to undergo gas-liquid two-phase mixing, using pneumatic shearing to refine the atomized particle size of the reducing agent. At the same time, the outermost protective sleeve 19 forms a barrier to isolate high-temperature flue gas. The outer airflow forms a temperature protection layer to prevent the reducing agent flowing inside from prematurely vaporizing or crystallizing due to high temperature, and to prevent unreacted escaped ammonia and dust in the flue gas from adhering and agglomerating at the nozzle tip to form ammonium salts, thereby avoiding nozzle tip blockage and flue corrosion.

[0032] A reducing agent solution inlet 21 is installed at one end of the reducing agent solution pipeline 18, and a mechanical conical atomizing nozzle 17 is installed at the other end. A swirl vane 16 is installed inside the reducing agent solution pipeline 18. During operation, the reducing agent solution flowing axially into the reducing agent solution pipeline 18 first passes through the swirl vane 16. The inclined guiding structure of the swirl vane 16 changes the fluid's trajectory, causing the fluid to generate tangential velocity and form a rotating flow, thus obtaining initial centrifugal force. Subsequently, the rotating fluid with centrifugal force enters the mechanical conical atomizing nozzle 17. The internal flow channel of this nozzle has a gradually narrowing structure, compressing the fluid and increasing its velocity. Through the guidance of the internal swirl vane 16 and the compression of the primary aperture of the end mechanical conical atomizing nozzle 17, the incoming reducing agent solution can be subjected to a first layer of rotational and breaking force. At the moment the fluid exits the orifice, the rotational centrifugal force and the sudden pressure drop overcome the surface tension of the liquid, causing the liquid column to break and disperse into primary droplets, providing a basis for the peripheral secondary pneumatic shear atomization.

[0033] One end of the compressed air pipe 15 is equipped with a compressed air inlet 22, and the other end is equipped with a fan-shaped air atomizing nozzle 14. The fan-shaped air atomizing nozzle 14 covers the periphery of the mechanical cone atomizing nozzle 17. High-speed compressed air is used to perform a second pneumatic shearing on the reducing agent of the primary atomization. This swirling atomization structure can ensure that the particle size of the final sprayed ammonia droplets is controlled within the range of ≤60μm, thereby increasing the surface area of ​​gas-liquid contact.

[0034] A soot blowing cooling air inlet 23 is installed on the side wall of the protective sleeve 19. Quick-connect flanges 20 are installed on both sides of the outer side of the protective sleeve 19. The medium introduced by the soot blowing cooling air inlet 23 can form an air film inside the protective sleeve 19, which can cool the core atomizing component in real time and blow away the particles attached to the end, avoid local ammonium salt crystallization blockage, and extend the service life of the equipment and catalyst layer 11.

[0035] A jet mixer 4 is installed on the left side of the outside of the flue gas duct 5. A dilution fan 3 is installed on the left side of the outside of the jet mixer 4. A flue gas denitrification unit 2 is installed on the left side of the outside of the dilution fan 3. An ammonia evaporator 1 is installed outside the flue gas denitrification unit 2. The ammonia evaporator 1, located at the front end, is responsible for receiving liquid ammonia solution and heating it to convert it into gaseous ammonia reducing agent. The vaporized reducing agent enters the flue gas denitrification unit 2 for buffering and stabilization before being transported. Then, the dilution fan 3 starts and introduces outside air. The power provided by the fan is used to collect the air and gaseous reducing agent to reduce the ammonia concentration and achieve a safe transport ratio. The mixed airflow transported by the fan then enters the jet mixer 4, where the airflow converges and is initially mixed in the flow channel with varying cross-section inside the jet mixer 4. This section, consisting of the ammonia evaporator 1, flue gas denitrification unit 2, dilution fan 3, and jet mixer 4, forms the pretreatment supply chain for the reducing agent, from liquid phase change vaporization, concentration dilution to initial mixing, providing raw materials that meet the requirements for subsequent injection of the reducing agent into the main reaction zone.

[0036] The device also includes a static mixer 24, which has cross-distributed swirl vanes installed inside. One end of the static mixer 24 is provided with a mixed gas inlet 25, and the other end is provided with a mixed gas nozzle 26. The static mixer 24 and its cooperating components constitute an ammonia and air mixing enhancement device. Through the deflection of the internal space of the static mixer 24 and the forced rotation generated by the cross-distributed swirl vanes, a dual mixing effect of the static mixer 24 and the swirl vanes is achieved. This ensures that ammonia and air are highly and fully mixed inside the static mixer 24 before being transported through the mixed gas nozzle 26 and finally injected into the flue gas, thus eliminating the potential danger of local over-mixing caused by uneven concentration of the reducing agent itself.

[0037] A laser emitter 29 is externally mounted on the denitrification outlet monitoring probe 28. The laser emitter 29 is installed at the pipe wall opening on one side of the exhaust port 8, with its emitting lens facing the internal center of the exhaust port 8. A multi-point distributed sensor 27 is installed externally on one side of the denitrification outlet monitoring probe 28. The multi-point distributed sensor 27 is installed on the pipe wall at the corresponding position on the other side of the exhaust port 8. It contains photoelectric conversion elements and signal amplification circuits. The probe and sensor assembly together constitute an online ammonia escape monitoring system. Unlike traditional single-point detection, the multi-point distributed sensor 27 works in conjunction with the laser emitter 29 to form a multi-point distributed detection system spanning the entire cross-section of the denitrification outlet. The laser monitoring network emits multiple wavelength laser beams from the laser emitter 29. These beams pass horizontally through the exhaust gas flow inside the exhaust port 8 and illuminate the receiving surface of the multi-point distributed sensors 27 arranged in a matrix on the opposite side. When the exhaust gas flow contains escaped ammonia, the ammonia molecules absorb some wavelengths of laser energy, causing the intensity of the laser beam received by the multi-point distributed sensors 27 to weaken. This enables high-precision acquisition of ammonia concentration data in each protection zone of the denitrification outlet. The multi-point distributed sensors 27 convert the attenuation of the laser beam intensity into an analog signal, which is then used to calculate the specific ammonia concentration value in each grid area. This solves the problem of lacking real-time ammonia escape monitoring feedback in existing technologies.

[0038] The device is also equipped with a PLC controller and an electric regulating valve. The electric regulating valve is installed on the ammonia injection grid 10. The denitrification outlet monitoring probe 28, the PLC controller, and the electric regulating valve are electrically connected. These three components together constitute the device's intelligent closed-loop regulation system. Specifically, the real-time monitoring data acquired by the multi-point distributed sensor 27 is immediately transmitted to the PLC controller. The PLC controller compares the target value with the data using a built-in algorithm. The upper limit of the ammonia slip rate of 3 ppm is pre-entered into the PLC controller's memory. The microprocessor reads the real-time values ​​sent by the multi-point distributed sensor 27 cyclically according to a set time period, and subtracts the real-time value from the pre-entered benchmark value to obtain the deviation difference. The microprocessor then outputs an electrical signal to the electric regulating valve in the corresponding area to adjust its opening. When the deviation difference is greater than zero, the PLC controller outputs a control voltage to drive the drive motor in that area to rotate forward, causing the valve core to reduce the channel cross-sectional area. When the concentration value returns to the set range, the PLC controller outputs a command to stop the drive motor. This intelligent closed-loop regulation system can achieve unattended automated operation.

[0039] The ammonia injection grid 10 is configured with multiple independent zones. Combined with the aforementioned electric regulating valve, it can correct the ammonia injection amount for each zone in real time, achieving automatic adjustment of the ammonia injection amount and uniform ammonia injection across the entire cross-section. Where excessive ammonia is detected, the ammonia injection amount in that zone is automatically reduced, eliminating localized ammonia excess and solving the problem of inaccurate ammonia injection control in traditional processes. This meets environmental protection requirements and saves 10%–20% of the ammonia injection amount, reducing the overall operating cost of the system. Simultaneously, to further ensure the uniformity of mixing, a multi-layer rectifier distribution plate is installed inside the flue gas duct 5 above the flue gas channel 12. This component constitutes the flue gas distribution structure of the device. The multi-layer rectifier distribution plate at the inlet can distribute and streamline the incoming raw flue gas, eliminating common flow deviation and eddy current phenomena in the raw flue gas duct, ensuring that the flue gas can enter the downstream denitrification reactor 6 uniformly and smoothly, thereby improving the mixing efficiency of flue gas and atomized ammonia in the ammonia mixing zone 13.

[0040] Working principle: Ammonia water first enters the ammonia evaporator 1 and is converted into ammonia gas or gaseous reducing agent. Then, under the action of the dilution fan 3, it mixes with air and enters the injection mixer 4 and the static mixer 24. The mixed gas enters the static mixer 24 through the mixed gas inlet 25. After double mixing by the internally cross-distributed swirl blades, it is discharged from the mixed gas nozzle 26, ensuring that ammonia and air reach a uniform state before being injected into the flue gas. At the same time, the raw flue gas enters the flue gas duct 5 and is rectified by the multi-layer rectifier and uniform distribution plate installed inside, eliminating flue gas deviation and eddies, and ensuring that the flue gas enters the flue gas channel 12 above the denitrification reactor 6 uniformly and smoothly.

[0041] The premixed ammonia gas or reducing agent solution is distributed to the ammonia injection grid 10 in the flue gas channel 12. Since the ammonia injection grid 10 is arranged in independent zones, the flow rate of each zone is independently controlled by the front-end electric regulating valve. The reducing agent enters the innermost reducing agent solution pipe 18 of the nozzle 9 through the reducing agent solution inlet 21, and rotates under the guidance of the internal swirl vane 16. Then it is sprayed out through the mechanical conical atomizing nozzle 17. At the same time, compressed air enters the compressed air pipe 15 through the compressed air inlet 22, and performs secondary shearing and pneumatic atomization on the centrally sprayed reducing agent through the outer fan-shaped air atomizing nozzle 14, controlling the ammonia droplet size to ≤60μm. In addition, the soot blowing cooling air enters the outermost protective sleeve 19 through the soot blowing cooling air inlet 23 to cool and prevent clogging of the entire nozzle 9, extending the nozzle life.

[0042] The refined and atomized ammonia gas is injected into the ammonia mixing zone 13, where it is deeply mixed with the uniformly flowed flue gas across the entire cross section. The uniformly mixed ammonia-containing flue gas flows downward through the catalyst layer 11. Under the action of the catalyst, the NOx in the flue gas undergoes a reduction reaction with the ammonia gas to generate harmless N2 and H2O, thus completing the denitrification process.

[0043] After the reaction is completed, the clean flue gas flows downward into the purified flue gas duct 7 and is discharged from the exhaust port 8. At the exhaust port 8, the laser emitter 29 emits a laser, which, together with the denitrification outlet monitoring probe 28 and the external multi-point distributed sensor 27, performs gridded and multi-point distributed real-time acquisition of ammonia escape concentration of the exhaust section. The ammonia concentration data of each area collected by the sensor is fed back to the PLC controller in real time. When the ammonia escape rate of a certain local area is detected to be close to or exceed the set threshold, such as 3ppm, the PLC controller calculates and outputs a command to adjust the electric regulating valve installed at the front end of the ammonia injection grille 10 in the corresponding zone, reducing or increasing the ammonia injection volume in that zone.

[0044] Through the closed-loop control of real-time monitoring, automatic feedback, and zoned adjustment, the phenomenon of local ammonia excess was eliminated, preventing ammonia escape from exceeding the standard and subsequent ammonium salt formation from clogging and corroding the equipment, thus realizing unattended automated denitrification.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for preventing ammonia escape during flue gas denitrification, comprising a denitrification reactor (6), characterized in that, A flue gas duct (5) is provided on the left side of the denitrification reactor (6). A flue gas channel (12), an ammonia mixing zone (13) and a catalyst layer (11) are arranged from top to bottom inside the denitrification reactor (6). An ammonia injection grid (10) is installed in the flue gas channel (12). Multiple nozzles (9) are installed on the ammonia injection grid (10). A purified flue gas duct (7) is provided on the right side of the denitrification reactor (6). A tail gas discharge port (8) is provided at the end of the purified flue gas duct (7). A denitrification outlet monitoring probe (28) is installed on the tail gas discharge port (8).

2. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, The nozzle (9) includes a reducing agent solution pipe (18), a compressed air pipe (15), and a protective sleeve (19). The reducing agent solution pipe (18) is disposed inside the compressed air pipe (15), and the compressed air pipe (15) is disposed inside the protective sleeve (19).

3. The device for preventing ammonia escape in flue gas denitrification according to claim 2, characterized in that, One end of the reducing agent solution pipeline (18) is equipped with a reducing agent solution inlet (21), and the other end is equipped with a mechanical conical atomizing nozzle (17). A swirl vane (16) is installed inside the reducing agent solution pipeline (18).

4. The device for preventing ammonia escape in flue gas denitrification according to claim 2, characterized in that, One end of the compressed air pipe (15) is equipped with a compressed air inlet (22), and the other end is equipped with a fan-shaped air atomizing nozzle (14).

5. The device for preventing ammonia escape in flue gas denitrification according to claim 2, characterized in that, The protective sleeve (19) is equipped with a soot blowing cooling air inlet (23) on its side wall, and quick-connect flanges (20) are installed on both sides of the outer side of the protective sleeve (19).

6. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, A jet mixer (4) is installed on the left side outside the flue gas duct (5). A dilution fan (3) is installed on the left side outside the jet mixer (4). A flue gas denitrification device (2) is installed on the left side outside the dilution fan (3). An ammonia water evaporator (1) is installed outside the flue gas denitrification device (2).

7. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, The device also includes a static mixer (24), which has cross-distributed swirl blades installed inside. One end of the static mixer (24) is provided with a mixed gas inlet (25), and the other end is provided with a mixed gas nozzle (26).

8. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, The external side of the denitrification outlet monitoring probe (28) is equipped with a laser emitting end (29), and a multi-point distributed sensor (27) is installed on one side of the external side of the denitrification outlet monitoring probe (28).

9. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, The device is also equipped with a PLC controller and an electric regulating valve. The electric regulating valve is installed on the ammonia injection grid (10). The denitrification outlet monitoring probe (28), the PLC controller and the electric regulating valve are electrically connected.

10. The device for preventing ammonia escape in flue gas denitrification according to claim 1, characterized in that, The ammonia injection grille (10) is configured with multiple independent zones, and the flue gas duct (5) above the flue gas passage (12) is equipped with a multi-layer rectifier distribution plate.

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