Long-lived, low-nitrogen emission microwave plasma assisted ammonia burner system and method

Abstract

The application discloses a long-life, low-nitrogen emission microwave plasma assisted ammonia burner system and method, which comprises a power supply, a microwave head, a circulator, a water load, a three-pin nail, a plasma ammonia burner, a short circuit piston, the plasma ammonia burner comprises a high-frequency igniter, a microwave plasma coupling cavity, a first-stage combustion reaction cavity, a second-stage combustion reaction cavity, a third-stage combustion reaction cavity and a tail gas emission collector. The application utilizes microwave plasma assisted combustion technology, ammonia staged combustion technology and low-nitrogen control technology to realize the long-life, low-nitrogen emission microwave plasma assisted ammonia combustion system, effectively improves ammonia combustion efficiency and reduces NOx emission generated by combustion, and is easy to enlarge to realize industrial production.

Description

Technical Field

[0001] This invention belongs to the field of low-temperature plasma-assisted combustion, specifically relating to a long-life, low-NOx emission microwave plasma-assisted ammonia burner system and method. Background Technology

[0002] Non-renewable fossil fuels such as coal, oil, and natural gas produce CO2 upon combustion, and their reserves are limited. Ammonia, as an excellent hydrogen storage medium, not only does not produce greenhouse gases during combustion, but also boasts a high octane number, resulting in excellent explosion-proof performance and superior safety. However, current ammonia energy development still faces certain challenges. Due to ammonia's high ignition point and slow flame propagation rate, combustion in boilers using pure ammonia as fuel is prone to instability and low power output. Furthermore, the presence of nitrogen atoms in ammonia fuel's chemical formula leads to the simultaneous production of both thermal and fuel-type NOx during combustion. Therefore, it is necessary to develop new technologies to improve the combustion characteristics of ammonia and effectively control the formation of various types of NOx during combustion. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a long-life, low-NOx microwave plasma-assisted ammonia burner system and method. It utilizes microwave plasma technology and staged combustion technology to achieve efficient combustion and low-NOx emission control in ammonia fuel combustion systems. Arc plasma uses electrical energy to ionize gas and generate thermal plasma, which features high temperature, concentrated energy, controllable atmosphere, and high heating rate. Compared with plasma generated by other gas discharge methods, microwave discharge plasma has advantages such as higher ionization density, wider discharge pressure range, stable discharge, and good controllability. Furthermore, its long lifespan, achieved without electrodes, makes it an important tool in energy, environment, materials preparation, and processing fields, playing an increasingly important role in modern industry. Using plasma-assisted ammonia combustion technology is an effective and feasible solution to ammonia combustion problems. The highly reactive particles in the plasma can greatly promote the ammonia combustion rate and alter the conversion of nitrogen (N) during combustion, significantly reducing NOx emissions.

[0004] The technical solution adopted in this invention is: a long-life, low-NOx emission microwave plasma-assisted ammonia burner system and method, including a power supply, a microwave head, a circulator, a water load, a three-pin, a plasma ammonia burner, a short-circuit piston, and a control system;

[0005] The plasma ammonia burner includes a high-frequency igniter, a microwave plasma coupling cavity, a first-stage combustion reaction cavity, a second-stage combustion reaction cavity, a third-stage combustion reaction cavity, and an exhaust gas emission collection and detection terminal;

[0006] The high-frequency igniter is used to generate pre-ionized plasma, assist microwave plasma ignition, and improve the working stability of microwave plasma. It includes a high-frequency power supply, a high-voltage transmission line, a plasma discharge cavity, and a high-frequency ignition gas inlet.

[0007] The microwave plasma coupling cavity is used to feed microwaves into the plasma ammonia burner. After ignition by the high-frequency igniter, the working gas in the coupling cavity is broken down by the microwaves to generate plasma. The cavity includes a coupling cavity air inlet assembly, a hollow inner conductor, a coaxial outer conductor, a coupling cavity rectangular waveguide, a coupling cavity wave converter, a cyclone ring, and a ceramic ring.

[0008] The first-stage combustion reaction chamber is used to realize the first-stage control of plasma-assisted ammonia fuel combustion, including a primary ammonia fuel inlet and a primary combustion air inlet;

[0009] The second-stage combustion reaction chamber is used to achieve the second-stage control of ammonia fuel combustion, including a secondary ammonia fuel inlet and a secondary combustion air inlet;

[0010] The third-stage combustion reaction chamber is used to realize the third-stage control of ammonia fuel combustion, including a tertiary combustion air inlet and a flame stabilizing component;

[0011] The exhaust emission detection terminal is used to detect the gas composition of the combustion gas, including a detection port and an online detector.

[0012] The specific technical solution is as follows:

[0013] A long-life, low-NOx emission microwave plasma-assisted ammonia burner system includes a power supply, a microwave head, a circulator, a water load, a three-pin connector, a plasma ammonia burner, a short-circuit piston, and a control system. The power supply is sequentially connected to the microwave head, circulator, three-pin connector, plasma ammonia burner, and short-circuit piston. The control system is connected to the plasma ammonia burner. The control system is also connected to the power supply. The circulator is connected to the water load.

[0014] The plasma ammonia burner includes a high-frequency igniter, a microwave plasma coupling cavity, a first-stage combustion reaction cavity, a second-stage combustion reaction cavity, a third-stage combustion reaction cavity, and an exhaust gas emission collection and detection terminal;

[0015] The high-frequency igniter is used to generate pre-ionized plasma, assist microwave plasma ignition, and improve the working stability of microwave plasma. It includes a high-frequency power supply, a high-voltage transmission line, a plasma discharge cavity, and a high-frequency ignition gas inlet. The high-frequency power supply is connected to the plasma discharge cavity through the high-voltage transmission line, and a high-frequency ignition gas inlet is provided on the plasma discharge cavity.

[0016] The microwave plasma coupling cavity is used to feed microwaves into the plasma ammonia burner. After ignition by the high-frequency igniter, the microwaves break down the working gas in the coupling cavity to generate plasma. The cavity includes a coupling cavity inlet assembly, a hollow inner conductor, a coaxial outer conductor, a coupling cavity rectangular waveguide, a coupling cavity wave converter, a cyclone ring, and a ceramic ring. The coupling cavity inlet assembly includes a microwave plasma working gas end and a microwave plasma working gas equalization end. The coaxial outer conductor sequentially connects the coupling cavity rectangular waveguide and the microwave plasma working gas equalization end. The coaxial outer conductor and the coupling cavity rectangular waveguide... Both the microwave plasma working gas distribution end and the microwave plasma working gas distribution end are sleeved on the outside of the hollow inner conductor; the microwave plasma working gas end is set on the microwave plasma working gas distribution end; a coupled cavity wave-to-same converter is set at the connection between the coupled cavity rectangular waveguide and the microwave plasma working gas distribution end; the coupled cavity rectangular waveguide is sequentially divided into an upper waveguide port, a wave-to-same conversion transition section, and a lower waveguide port; a swirling gas ring is set inside the coaxial outer conductor; a ceramic ring is set at the end of the coaxial outer conductor; the outlet of the coaxial outer conductor is sequentially set with a first-stage combustion reaction chamber, a second-stage combustion reaction chamber, and a third-stage combustion reaction chamber;

[0017] The first-stage combustion reaction chamber is used to realize the first-stage control of plasma-assisted ammonia fuel combustion, including a primary ammonia fuel inlet and a primary combustion air inlet;

[0018] The second-stage combustion reaction chamber is used to achieve the second-stage control of ammonia fuel combustion, including a secondary ammonia fuel inlet and a secondary combustion air inlet;

[0019] The third-stage combustion reaction chamber is used to realize the third-stage control of ammonia fuel combustion, including a tertiary combustion air inlet and a flame stabilizing component;

[0020] The exhaust emission detection terminal is used to detect the gas composition of the combustion gas, including a detection port and an online detector.

[0021] Furthermore, in the long-life, low-NOx emission microwave plasma-assisted ammonia burner system, the low-power microwave power supply has a frequency of 2.45 GHz or 915 MHz.

[0022] Furthermore, in the long-life, low-NOx emission microwave plasma-assisted ammonia burner system, the microwave plasma coupling cavity, the first-stage combustion reaction cavity, the second-stage combustion reaction cavity, and the third-stage combustion reaction cavity are at atmospheric pressure or at an ultra-atmospheric pressure of 1-10 atm.

[0023] Furthermore, in the long-life, low-NOx emission microwave plasma-assisted ammonia burner system, the fuel used in the reactions of the first-stage combustion reaction chamber, the second-stage combustion reaction chamber, and the third-stage combustion reaction chamber is natural gas, ammonia, hydrogen, ethane, propane, pulverized coal, gasoline, or diesel.

[0024] Furthermore, in the long-life, low-NOx emission microwave plasma-assisted ammonia burner system, the microwave head outputs microwaves at a single frequency point in the range of 1GHz-10GHz or a microwave frequency band with a certain bandwidth.

[0025] This invention also discloses a method for generating a long-life, low-NOx emission microwave plasma-assisted ammonia burner, comprising: connecting the high-frequency igniter system to the microwave plasma coupling cavity; rotating and introducing high-frequency ignition plasma discharge gas from the center of the high-frequency igniter plasma discharge cavity; the high-frequency igniter generating a high-frequency electric field to excite the high-frequency ignition plasma discharge gas introduced from the center of the high-frequency igniter plasma discharge cavity to form primary plasma; placing the high-frequency igniter at the top center of the hollow inner conductor in the microwave plasma coupling cavity; the working gas of the coupling cavity entering the system through the coupling cavity air inlet assembly along the gap between the hollow inner conductor and the coaxial outer conductor in the microwave plasma coupling cavity; initially introducing the high-frequency ignition plasma discharge gas and the coupling cavity working gas during system startup, then starting the high-frequency igniter; after generating the primary plasma, starting the power supply to generate microwave plasma; and waiting for the... After the microwave plasma is generated and stabilized, the high-frequency igniter is shut off, and the high-frequency ignition plasma discharge gas is continuously introduced. The first-stage ammonia fuel and the first-stage combustion air are introduced through the first-stage combustion reaction chamber, and stable and efficient combustion is achieved under the assistance of the microwave plasma. The first-stage ammonia fuel and the first-stage combustion air are detected, regulated, and controlled by the control system. The second-stage ammonia fuel and the second-stage combustion air are introduced through the second-stage combustion reaction chamber, and stable and efficient combustion is achieved under the assistance of the microwave plasma. The second-stage ammonia fuel and the second-stage combustion air are detected, regulated, and controlled by the control system. The third-stage combustion air is introduced through the third-stage combustion reaction chamber to further and fully combust the residual fuel from the previous combustion stages and control the gas temperature. The amount of the third-stage combustion air is monitored, regulated, and controlled by the control system. Ultimately, a long-life, low-NOx emission microwave plasma-assisted ammonia burner system is obtained.

[0026] The advantages of this invention are:

[0027] This invention utilizes high-power microwave generation and transmission technology, plasma-assisted combustion technology, and low-NOx emission combustion organization technology to achieve a high-efficiency ammonia combustion and low-NOx emission system assisted by high-power microwave plasma. It effectively improves the absorption efficiency of high-power microwaves in plasma, enhances the combustion efficiency of ammonia fuels with low combustion characteristics, and effectively reduces NOx emissions. The microwave plasma technology involved in this invention can be used for the synthesis and preparation of high-purity, high-melting-point materials, as well as for the auxiliary combustion of fuels such as pulverized coal, ammonia, and natural gas. It can also replace traditional oil or plasma torches for ignition and stable combustion in coal-fired power plants, and can replace high-power burners in scenarios such as cement kilns, blast furnaces, and hydrogen-based vertical shaft furnaces. Compared to traditional high-power plasma torch technology, microwave plasma has the characteristics of higher efficiency and longer lifespan, achieving a longer burner system lifespan in conjunction with the burner system. During the reaction process, using low-power plasma to ignite high-power microwave plasma significantly improves the flexibility and stability of the equipment. The size of the device can be flexibly adjusted as needed, greatly reducing the development difficulty and material manufacturing cost of the equipment, and facilitating scale-up for industrial production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the main components of the microwave plasma-assisted ammonia combustion system of the present invention;

[0029] Figure 2 This is a flowchart illustrating the operation of the ammonia burner components and control system of the present invention.

[0030] Figure 3 This is a schematic diagram of the microwave plasma-assisted ammonia burner structure of the present invention.

[0031] In the diagram, 01 is the auxiliary air intake end, 02 is the high-frequency igniter working gas intake end, 03 is the high-frequency igniter, 04 is the hollow inner conductor, 05 is the microwave plasma working gas end, 06 is the microwave plasma working gas equalization end, 07 is the wave-to-same converter, 08 is the upper port of the waveguide, 09 is the lower port of the waveguide, 10 is the wave-to-same conversion transition section, 11 is the coaxial outer conductor, 12 is the primary fuel intake end, 13 is the secondary air intake end, 14 is the secondary fuel intake end, 15 is the tertiary air intake end, 16 is the cyclone ring, 17 is the ceramic ring, I is the primary combustion zone, II is the secondary combustion zone, and III is the tertiary combustion zone. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The specific application and implementation methods of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 This is a schematic diagram of the main components of the long-life, low-NOx emission microwave plasma-assisted ammonia burner system of the present invention. The long-life, low-NOx emission microwave plasma-assisted ammonia burner system of the present invention includes a power supply, a microwave head, a circulator, a water load, a three-pin connector, a plasma ammonia burner, a short-circuit piston, and a control system. The control system is connected to the plasma ammonia burner. The control system is connected to the power supply. The circulator is connected to the water load. The power supply is sequentially connected to the microwave head, circulator, three-pin connector, plasma ammonia burner, and short-circuit piston.

[0035] like Figure 2 The flowchart of the ammonia burner components and control system of the present invention is shown. It includes an ammonia burner, ammonia fuel, an air source, a tail gas emission collection and detection system, a microwave plasma system, a high-frequency igniter, and a control system. The air source is divided into two paths: one is combustion air directly supplied to the ammonia burner, and the other is the plasma working gas. The plasma working gas is further divided into two paths: one is sequentially supplied to the high-frequency igniter and the microwave plasma, and the other is directly supplied to the microwave plasma as the microwave plasma discharge gas. The combustion air is directly supplied to the ammonia burner to participate in the ammonia combustion process. The tail gas emission collection and detection system is used to detect ammonia combustion. After combustion, the burner produces NOx and temperature parameters in the exhaust gas, which are then fed back to the control system to adjust the parameters of the entire system. The control system is connected to the air source, the combustion air, the plasma working gas, the high-frequency igniter, the microwave plasma, the ammonia fuel, and the exhaust gas emission collection and detection system. By communicating with the exhaust gas emission collection and detection system, the control system can bidirectionally detect and control the ammonia fuel, the combustion air, the air source, the plasma working gas, the high-frequency igniter, the microwave plasma, and other components to achieve control of the ammonia burner.

[0036] like Figure 3This is a schematic diagram of the microwave plasma-assisted ammonia burner structure of the present invention. The plasma ammonia burner includes a high-frequency igniter 03, a microwave plasma coupling cavity, a first-stage combustion reaction cavity, a second-stage combustion reaction cavity, a third-stage combustion reaction cavity, and a tail gas emission collection and detection end. Specifically, the microwave plasma-assisted ammonia burner includes an auxiliary air inlet end 01, a high-frequency igniter working gas inlet end 02, a high-frequency igniter 03, a hollow inner conductor 04, a microwave plasma working gas end 05, a microwave plasma working gas equalization end 06, a wave-to-same converter 07, a waveguide upper port 08, a waveguide lower port 09, a wave-to-same conversion transition section 10, a coaxial outer conductor 11, a first-stage fuel inlet end 12, a second-stage air inlet end 13, a second-stage fuel inlet end 14, a third-stage air inlet end 15, a cyclone ring 16, a ceramic ring 17, a first-stage combustion zone I, a second-stage combustion zone II, and a third-stage combustion zone III.

[0037] The microwave power supply is connected to the microwave plasma coupling cavity.

[0038] The high-frequency igniter 03 is used to generate pre-ionized plasma, assisting microwave plasma ignition and improving the operational stability of the microwave plasma. The high-frequency igniter includes a high-frequency power supply, a high-voltage transmission line, a plasma discharge cavity, and a high-frequency ignition gas inlet. The working gas inlet 02 of the high-frequency igniter is connected to the high-frequency igniter through the high-frequency ignition gas inlet. The high-frequency power supply is connected to the plasma discharge cavity through the high-voltage transmission line, and the plasma discharge cavity is equipped with a high-frequency ignition gas inlet. The high-frequency igniter is placed at the top center of the hollow inner conductor 04 within the microwave plasma coupling cavity. The coaxial outer conductor 11 is coaxially arranged with the hollow inner conductor 04. The auxiliary gas inlet 01 is placed in the gap between the high-frequency igniter 03 and the inner hole of the hollow inner conductor 04, used to introduce air or ammonia fuel, cooling the hollow inner conductor and promoting combustion in the primary combustion zone I. The microwave plasma coupling cavity is used to feed microwaves into the plasma ammonia burner. After ignition by the high-frequency igniter 03, the microwaves break down the working gas in the coupling cavity to generate plasma. The microwave plasma coupling cavity includes a coupling cavity inlet assembly, a hollow inner conductor 04, a coaxial outer conductor 11, a coupling cavity rectangular waveguide, a coupling cavity wave-to-same converter 07, a swirling gas ring 16, and a ceramic ring 17. The coupling cavity inlet assembly includes a microwave plasma working gas end 05 and a microwave plasma working gas equalization end 06. The coaxial outer conductor 11 connects the coupling cavity rectangular waveguide and the microwave plasma working gas equalization end 06 in sequence. The coaxial outer conductor 11, the coupling cavity rectangular waveguide, and the microwave plasma working gas equalization end 06 are all sleeved outside the hollow inner conductor 04. The microwave plasma working gas end 05 is located on the microwave plasma working gas equalization end 06. The coupling cavity wave-to-same converter 07 is located at the connection between the coupling cavity rectangular waveguide and the microwave plasma working gas equalization end 06. The coupling cavity rectangular waveguide is sequentially divided into an upper waveguide port 08, a wave-to-same conversion transition section 10, and a lower waveguide port 09. The primary fuel inlet 12, secondary air inlet 13, secondary fuel inlet 14, and tertiary air inlet 15 are each independently connected to the coaxial outer conductor 11. A cyclone ring 16 is disposed within the coaxial outer conductor 11. A ceramic ring 17 is disposed at the end of the coaxial outer conductor 11. The outlet of the coaxial outer conductor 11 is sequentially provided with a primary combustion zone I (i.e., the first-stage combustion reaction chamber), a secondary combustion zone II (i.e., the second-stage combustion reaction chamber), and a tertiary combustion zone III (i.e., the third-stage combustion reaction chamber).

[0039] The hollow inner conductor 04 is connected to the tail of the microwave plasma working gas equalization end 06 via a threaded connection or a sealing ring, used to evenly distribute the air entering from the microwave plasma working gas end 05 into the primary combustion zone I. The microwave plasma working gas equalization end 06 is fixed to the side of the wave-to-phase conversion transition section via a thread. The microwave plasma working gas equalization end 06 is connected to the wave-to-phase converter 07 via a thread, which is used to convert the microwave mode from TE10 mode to TEM electromagnetic wave mode. The upper port 08 and lower port 09 of the waveguide are respectively connected to the three pins and the short-circuit piston for efficient transmission of electromagnetic waves. The coaxial outer conductor 11 is connected to the wave-to-phase conversion transition section 10 via a thread, so that the electromagnetic waves are transmitted forward in TEM mode. The primary fuel inlet end 12 introduces ammonia fuel into the system, which interacts with the microwave plasma in the primary combustion zone I. Air plasma, generated by ionization, enters through the working gas end 05 and participates in combustion; the secondary air inlet end 13 is used to introduce air participating in secondary combustion, which mixes with the primary combustion zone I and continues to enhance combustion in the secondary combustion zone II; the secondary fuel inlet end 14 is used to introduce ammonia fuel, which mixes with the secondary combustion zone II and continues to enhance combustion in the tertiary combustion zone III; the tertiary air inlet end 15 is used to introduce excess air, which is used to continue mixing in the tertiary combustion zone III and thus burn off the residual fuel in the tertiary combustion zone III, while controlling the gas temperature in the tertiary combustion zone III; the swirling ring 16 is used to form a swirling flow of air entering through the microwave plasma working gas end 05, enhancing the stability of the plasma generated after being ionized by microwaves; the ceramic ring 17 is fixed inside the coaxial outer conductor 11 for efficient transmission of electromagnetic waves and efficient coupling with the microwave plasma.

[0040] Preferably, the frequency of the microwave power supply is 2.45 GHz or 915 MHz.

[0041] Preferably, the working pressure of the primary combustion zone I, the secondary combustion zone II, and the tertiary combustion zone III is atmospheric pressure or ultra-atmospheric pressure of 1-10 atm.

[0042] Preferably, the fuel used in the reaction in which the fuel combustion provides heat energy is natural gas, ammonia, hydrogen, ethane, propane, pulverized coal, gasoline, or diesel.

[0043] Preferably, the low-power microwave power supply has a frequency of a single frequency point in the range of 1GHz-10GHz or a microwave frequency band with a certain bandwidth.

[0044] The working method of this invention is as follows:

[0045] The high-frequency igniter system is connected to the microwave plasma coupling cavity. High-frequency ignition plasma discharge gas is introduced from the center of the plasma discharge cavity of the high-frequency igniter 03. The high-frequency igniter 03 generates a high-frequency electric field to excite the high-frequency ignition plasma discharge gas introduced from the center of the high-frequency igniter plasma discharge cavity, thereby forming primary plasma. The high-frequency igniter 03 is placed at the top center of the hollow inner conductor 04 in the microwave plasma coupling cavity. The working gas of the coupling cavity enters the system through the microwave plasma working gas distribution end 06 along the gap between the hollow inner conductor 04 and the coaxial outer conductor 11 in the microwave plasma coupling cavity. In the initial stage of system startup, the high-frequency ignition plasma discharge gas and the working gas of the coupling cavity are introduced first, then the high-frequency igniter 03 is started. After the primary plasma is generated, the microwave power supply is started to generate microwave plasma. The microwave plasma is then generated. After the plasma is generated and stabilized, the high-frequency igniter 03 is shut off, and the high-frequency ignition plasma discharge gas is continuously introduced. The primary ammonia fuel and the primary combustion air are introduced through the first-stage combustion reaction chamber, and stable and efficient combustion is achieved under the assistance of the microwave plasma. The amounts of the primary ammonia fuel and the primary combustion air are detected, adjusted, and controlled by the control system. The secondary ammonia fuel and the secondary combustion air are introduced through the second-stage combustion reaction chamber, and stable and efficient combustion is achieved under the assistance of the microwave plasma. The amounts of the secondary ammonia fuel and the secondary combustion air are detected, adjusted, and controlled by the control system. The tertiary combustion air is introduced through the third-stage combustion reaction chamber to further and fully combust the residual fuel from the previous combustion stages and to control the gas temperature. The amount of the tertiary combustion air is monitored, adjusted, and controlled by the control system. Finally, a long-life, low-NOx emission microwave plasma-assisted ammonia burner system is obtained.

[0046] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A long lifetime, low nitrogen emission microwave plasma assisted ammonia burner system characterized by: The device comprises a power supply, a microwave head, a circulator, a water load, a three-pin, a plasma ammonia burner, a short circuit piston, a control system; the power supply is connected to the microwave head, the circulator, the three-pin, the plasma ammonia burner and the short circuit piston in sequence; the control system is connected to the plasma ammonia burner; the control system is connected to the power supply; the circulator is connected to the water load. The plasma ammonia burner comprises a high-frequency igniter, a microwave plasma coupling cavity, a first-stage combustion reaction cavity, a second-stage combustion reaction cavity, a third-stage combustion reaction cavity and a tail gas discharge collection and detection end. The high-frequency igniter is used to generate pre-ionized plasma, assist microwave plasma ignition and improve microwave plasma working stability, and comprises a high-frequency power supply, a high-voltage transmission line, a plasma discharge cavity and a high-frequency ignition gas inlet; the high-frequency power supply is connected to the plasma discharge cavity through the high-voltage transmission line, and the plasma discharge cavity is provided with the high-frequency ignition gas inlet. The microwave plasma coupling cavity is used to feed microwaves into the plasma ammonia burner, and generate plasma under the action of microwaves after the high-frequency igniter is ignited; the microwave plasma coupling cavity comprises a coupling cavity gas inlet assembly, a hollow inner conductor, a coaxial outer conductor, a coupling cavity rectangular waveguide, a coupling cavity wave same converter, a gas rotating ring and a ceramic ring; the coupling cavity gas inlet assembly comprises a microwave plasma working gas end and a microwave plasma working gas equal division end; the coaxial outer conductor is connected to the coupling cavity rectangular waveguide and the microwave plasma working gas equal division end in sequence, and the coaxial outer conductor, the coupling cavity rectangular waveguide and the microwave plasma working gas equal division end are all arranged outside the hollow inner conductor; the microwave plasma working gas end is arranged on the microwave plasma working gas equal division end; the coupling cavity rectangular waveguide and the microwave plasma working gas equal division end are provided with the coupling cavity wave same converter at the connection position; the coupling cavity rectangular waveguide is divided into a waveguide upper end port, a wave same conversion transition section and a waveguide lower end port in sequence; the gas rotating ring is arranged in the coaxial outer conductor; the ceramic ring is arranged at the end of the coaxial outer conductor; the outlet of the coaxial outer conductor is provided with the first-stage combustion reaction cavity, the second-stage combustion reaction cavity and the third-stage combustion reaction cavity in sequence. The first-stage combustion reaction cavity is used to realize first-stage control of plasma assisted ammonia fuel combustion, and comprises a primary ammonia fuel gas inlet end and a primary combustion air gas inlet end. The second-stage combustion reaction cavity is used to realize second-stage control of ammonia fuel combustion, and comprises a secondary ammonia fuel gas inlet end and a secondary combustion air gas inlet end. The third-stage combustion reaction cavity is used to realize third-stage control of ammonia fuel combustion, and comprises a tertiary combustion air gas inlet end and a flame stabilizing component. The tail gas discharge detection end is used to detect the gas composition of the combustion gas, and comprises a detection port and an online detector.

2. The long lifetime, low nitrogen emission microwave plasma assisted ammonia burner system of claim 1, wherein: The microwave plasma coupling cavity, the first-stage combustion reaction cavity, the second-stage combustion reaction cavity and the third-stage combustion reaction cavity are normal pressure or 1-10 atm overpressure.

3. The long lifetime, low nitrogen emission microwave plasma assisted ammonia burner system of claim 1, wherein: The frequency of the microwave output by the microwave head is a single frequency point or a microwave frequency section with a certain bandwidth in the range of 1 GHz-10 GHz.

4. The method of operating a long lifetime, low nitrogen emission microwave plasma assisted ammonia burner of any of claims 1-3, characterized in that: The high-frequency igniter system is connected with the microwave plasma coupling cavity, high-frequency ignition plasma discharge gas is rotated from the center of the high-frequency igniter plasma discharge cavity; the high-frequency igniter generates a high-frequency electric field to excite the high-frequency ignition plasma discharge gas from the center of the high-frequency igniter plasma discharge cavity to form a primary plasma; the high-frequency igniter is placed at the center top end of the hollow inner conductor in the microwave plasma coupling cavity, the coupling cavity working gas enters the system through the gap between the hollow inner conductor and the coaxial outer conductor in the microwave plasma coupling cavity through the coupling cavity gas inlet assembly; the high-frequency ignition plasma discharge gas and the coupling cavity working gas are first introduced at the initial stage of system start-up, then the high-frequency igniter is started, the microwave plasma is generated after the primary plasma is generated, the high-frequency igniter is turned off after the microwave plasma is generated and stabilized, and the high-frequency ignition plasma discharge gas is continuously introduced; first-stage ammonia fuel and first-stage combustion air are introduced through the first-stage combustion reaction cavity and burned under the assistance of the microwave plasma, the amount of the first-stage ammonia fuel and the first-stage combustion air is detected, adjusted and controlled through the control system; second-stage ammonia fuel and second-stage combustion air are introduced through the second-stage combustion reaction cavity and stably and efficiently burned under the assistance of the microwave plasma, the amount of the second-stage ammonia fuel and the second-stage combustion air is detected, adjusted and controlled through the control system; third-stage combustion air is introduced through the third-stage combustion reaction cavity, used for further fully burning the residual fuel of the previous stage and controlling the gas temperature, and the amount of the third-stage combustion air is monitored, adjusted and controlled through the control system; and finally, a long-life, low-nitrogen emission microwave plasma assisted ammonia combustor system is obtained.

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