Low-temperature low-nitrogen green ammonia coal compound combustion system of large wall type tangential boiler

Abstract

The invention discloses a low-temperature and low-nitrogen green ammonia coal compound combustion system of a large wall type tangential boiler, which is characterized in that one end of a green ammonia pipe of a green ammonia burner nozzle is communicated with the output end of a green ammonia synthesizer, the other end of the green ammonia pipe is respectively communicated with the input ends of two green ammonia speed-reducing and pressurizing devices through lead-in pipelines, and a valve is arranged on the green ammonia pipe; the green ammonia speed reducing and pressurizing device is of a box body structure, and the end face of the output end is fixedly connected with a green ammonia nozzle; a channel between the two green ammonia speed reducing and pressurizing devices is a combustion-supporting air channel; the shell, the peripheral air separation wall and the Venturi tube wall are sequentially arranged from outside to inside in a sleeved mode, and the green ammonia speed reducing and pressurizing device is fixedly connected to the inner side, close to the output end, of the Venturi tube wall. A cavity between the peripheral air separation wall and the shell is used as a peripheral air channel; and a cavity between the pipe wall of the Venturi pipe and the peripheral air separation wall is used as an air distribution channel. The low-temperature, low-nitrogen and homogeneous-like combustion can be realized, and the emission of NOx is reduced.

Description

Technical Field

[0001] The invention relates to the field of large boiler combustion, and in particular to a low-temperature, low-nitrogen, green ammonia-coal composite combustion system for a large wall-type tangentially-circular boiler. Background Art

[0002] The ammonia-coal blending is a technical realization of the efficient combination of renewable zero-carbon energy and traditional utilization methods, and is an important way to gradually decarbonize national economy and people's livelihood such as low-carbon power generation and clean heating. However, the existing large-scale boiler wall-type tangential pulverized coal boiler ammonia blending combustion is simply to send ammonia and pulverized coal into the furnace. The high-proportion ammonia blending combustion has key technical bottlenecks such as rate mismatch and large differences in NOx generation, which seriously restricts its large-scale development. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention proposes a low-temperature, low-nitrogen, green ammonia coal composite combustion system for a large wall-type tangentially-circular boiler.

[0004] The specific technical solutions are as follows:

[0005] A green ammonia burner nozzle, whose output end outputs green ammonia to the combustion zone of the boiler, comprises: a green ammonia nozzle, an air distribution nozzle, a green ammonia speed reduction and pressure boosting device, a combustion-supporting air channel, an introduction pipeline, a venturi tube, a green ammonia pipe, a valve, a green ammonia synthesis device, a shell, and a peripheral wind partition wall;

[0006] One end of the green ammonia pipe is connected to the output end of the green ammonia synthesis device, and the other end is connected to the input ends of the two green ammonia speed reduction and pressure boosting devices through the introduction pipeline. A valve is arranged on the green ammonia pipe; the green ammonia speed reduction and pressure boosting device is a box structure, and a guide plate is arranged inside it. A green ammonia nozzle is fixedly connected to the end face of the output end, and the green ammonia nozzle is a plate with multiple regular through holes; the channel between the two green ammonia speed reduction and pressure boosting devices is a combustion-supporting air channel;

[0007] The outer shell, the peripheral wind partition wall, and the venturi tube wall are sequentially arranged from the outside to the inside, and the green ammonia speed reduction and pressurization device is fixedly connected to the inner side of the venturi tube wall near the output end; the cavity between the peripheral wind partition wall and the outer shell serves as a peripheral wind channel; one end of the venturi tube wall is flush with the output end of the green ammonia nozzle, and the other end is inclined toward the outer shell, and the cavity between it and the peripheral wind partition wall serves as an air distribution channel.

[0008] Furthermore, a damper plate is provided in the air distribution channel for adjusting the air volume and wind speed.

[0009] Furthermore, it also includes a wind speed measuring device, which is arranged in the air distribution channel and is used to measure the hot air volume.

[0010] A low-temperature, low-nitrogen, green ammonia-coal composite combustion system for a large wall-type tangentially-shaped boiler, comprising four groups arranged along the boiler, each group comprising a separate overburnt air burner and at least one green ammonia-coal composite burner; the four groups of separate overburnt air burners are arranged in four corners or four walls, and the green ammonia-coal composite burners are arranged in four walls;

[0011] The green ammonia coal composite burner includes in order: an upper hot air nozzle, a first low-nitrogen burner, a first green ammonia burner nozzle, a second low-nitrogen burner, an intermediate hot air nozzle, a first plasma or micro-oil ignition burner nozzle, a second green ammonia burner nozzle, a second plasma or micro-oil ignition burner nozzle, and a lower hot air nozzle;

[0012] The two low-nitrogen burners and the two plasma or micro-oil ignition burner nozzles are all pulverized coal combustion devices. The green ammonia burner nozzle is used to deliver green ammonia and hot air into the boiler combustion zone. The pulverized coal combustion device is used to deliver pulverized coal and primary hot air into the boiler combustion zone. The two plasma or micro-oil ignition burner nozzles are also used for ignition. The upper hot air nozzle, the middle hot air nozzle, and the lower hot air nozzle are used to supplement secondary hot air to the boiler combustion zone.

[0013] Furthermore, air dampers are respectively provided in the upper hot air nozzle, the middle hot air nozzle and the lower hot air nozzle to adjust the air volume and wind speed of the secondary hot air.

[0014] Furthermore, a flame monitoring device is provided in the combustion system, and the detection result is fed back to the control system to adjust the combustion conditions in real time; the control system includes a programmable logic controller and a distributed control system.

[0015] The beneficial effects of the present invention are:

[0016] The system of the present invention can be equipped with the ability to burn more than 10% green ammonia, and the coal consumption and carbon emission levels are significantly reduced; the system of the present invention adopts a wall-type layout, the furnace is more full, the flame is wider and more uniform, and low-temperature, low-nitrogen, quasi-homogeneous combustion can be achieved, NO x Lower emissions and better environmental performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of a green ammonia burner nozzle provided in an embodiment of the present invention, wherein (a) is a left view and (b) is a front view.

[0018] Figure 2 It is a schematic diagram of the overall structure of a low-temperature, low-nitrogen, green ammonia-coal composite combustion system for a large wall-type tangential circle boiler provided in an embodiment of the present invention.

[0019] Figure 3 yes Figure 2A schematic diagram of the structure of a medium-separated ember-burning wind device, wherein (a) is a front view of a single separated ember-burning wind device, and (b) is a cross-sectional view of the layer where the separated ember-burning wind device is located when the system is divided into four groups and arranged along the furnace.

[0020] Figure 4 yes Figure 2 Schematic diagram of the structure of the medium green ammonia coal composite burner, where (a) is the main view, (b) is the cross-sectional view of the layer where the green ammonia burner nozzle is located when the system is divided into four groups and arranged along the furnace, and (c) is the cross-sectional view of the layer where the low nitrogen burner is located when the system is divided into four groups and arranged along the furnace.

[0021] In the figure, a green ammonia burner nozzle 1, a green ammonia nozzle 1-1, an air distribution channel 1-2, a green ammonia speed reduction and pressure boosting device 1-3, a combustion-supporting air channel 1-4, an introduction pipeline 1-5, a venturi tube 1-6, a green ammonia tube 1-7, a valve 1-8, a green ammonia synthesis device 1-9, a shell 1-10, a peripheral wind partition wall 1-11, and a wind speed measuring device 1-12;

[0022] Separate overburnt air burner 2, green ammonia coal composite burner 3, upper hot air nozzle 3-1, low nitrogen burner 3-2, middle hot air nozzle 3-3, plasma or micro-oil ignition burner nozzle 3-4, lower hot air nozzle 3-5. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effect of the present invention will become more clear. The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Before further describing the embodiments of the present invention in detail, the nouns and terms involved in the embodiments of the present invention are described. The nouns and terms involved in the embodiments of the present invention are subject to the following explanations.

[0025] (1) Green hydrogen refers to hydrogen obtained by decomposing water using renewable energy (such as wind energy, solar energy, etc.). Since it does not produce carbon dioxide during the production process and achieves zero carbon dioxide emissions from the source, it is regarded as one of the clean energy sources with the greatest development potential.

[0026] (2) Green ammonia refers to ammonia that is directly synthesized by catalysts at room temperature and pressure using air and water as raw materials, driven by renewable energy. Unlike traditional ammonia production methods, the production process of green ammonia does not rely on fossil energy. It is essentially a zero-carbon fuel that only produces nitrogen and water after combustion, and no carbon dioxide.

[0027] (3) Low nitrogen burner is a kind of burner used in the field to reduce nitrogen oxides (NO x) emissions and optimize the combustion process. By adjusting the mixing ratio, speed and temperature of primary air and pulverized coal, uniform combustion of pulverized coal is achieved, which helps to reduce local high temperature areas during the combustion process, thereby reducing NO x The generation of NO is suppressed by adopting specific burner structure and air flow regulation methods, such as staged combustion and air staging, to reduce the oxygen concentration during the combustion process. x Generation of.

[0028] (4) Plasma or micro-oil ignition burners are two different types of ignition burners commonly used in this field. Among them, the plasma ignition burner is a coal powder burner equipped with a plasma generator and uses plasma for ignition and stable combustion. It has a fast ignition speed and a high flame temperature. It is more suitable for those types of coal that are difficult to ignite and have poor stable combustion performance, as well as occasions that require high temperature and high energy characteristics; the micro-oil ignition burner is a burner that uses a small amount of fuel oil or gas to ignite the coal powder airflow. It is more suitable for boilers that need to be frequently started and shut down, as well as occasions with strict requirements on oil consumption. Both types of ignition burners have strong adaptability to coal types and can ignite various types of coal powder airflows.

[0029] (5) Separated Over Fire Air (SOFA), also known as overfire air, is a burner used to improve combustion efficiency and reduce nitrogen oxides (NO x There is a distance between the SOFA device and the main burner, which makes the NO generated in the main burner area x In a reducing atmosphere, it is reduced to nitrogen (N2). This reaction process is relatively slow and requires sufficient time to complete. After this distance, SOFA air is added to achieve complete combustion of the remaining fuel. In addition, SOFA air can also reduce the NO x and the deviation of flue gas temperature, which is achieved through cyclone elimination technology, which can reduce the four-corner cutting circle deviation.

[0030] Based on the above structure, the embodiment of the present invention proposes a green ammonia burner nozzle, such as Figure 1 As shown, the green ammonia burner nozzle 1 includes: a green ammonia nozzle 1-1, an air distribution channel 1-2, a green ammonia speed reduction and pressure boosting device 1-3, a combustion-supporting air channel 1-4, an introduction pipeline 1-5, a venturi tube wall 1-6, a green ammonia tube 1-7, a valve 1-8, a green ammonia synthesis device 1-9, a shell 1-10, a peripheral wind partition wall 1-11, and a wind speed measuring device 1-12. The green ammonia nozzle 1-1 is made of wear-resistant and high-temperature resistant silicon carbide material.

[0031] The green ammonia synthesis device 1-9 is used to convert the input green hydrogen into green and environmentally friendly green ammonia. The output end of the green ammonia synthesis device 1-9 is connected to the input end of the green ammonia speed reduction and pressure boosting device 1-3 through the green ammonia pipe 1-7. The green ammonia pipe 1-7 is provided with a valve 1-8 for controlling the green ammonia flow rate; when there are multiple green ammonia speed reduction and pressure boosting devices 1-3, when the green ammonia pipe 1-7 is connected to the green ammonia speed reduction and pressure boosting device 1-3, the diversion is achieved by introducing the pipeline 1-5. The green ammonia synthesis device 1-9 is generally arranged outside the burner and is connected to the inside of the burner through the green ammonia pipe 1-7.

[0032] The green ammonia speed reduction and pressure boosting device 1-3 is a box structure, and a green ammonia nozzle 1-1 is fixedly connected to the end surface of the output end thereof. The green ammonia nozzle 1-1 is a plate with a plurality of regular through holes. A guide plate is arranged inside the green ammonia speed reduction and pressure boosting device 1-3 to make the green ammonia entering the green ammonia nozzle 1-1 more uniform, so that it can enter the boiler combustion zone more uniformly through the green ammonia nozzle 1-1. Due to the arrangement of the green ammonia nozzle 1-1, the flow rate of green ammonia is reduced, and the pressure inside the green ammonia speed reduction and pressure boosting device 1-3 is increased, which helps the green ammonia enter the boiler combustion zone at a suitable speed.

[0033] In this embodiment, the green ammonia speed reduction and pressure boosting devices 1-3 are symmetrically arranged along the central axis of the green ammonia burner nozzle 1, and there is a distance between the two green ammonia speed reduction and pressure boosting devices 1-3. The central channel serves as the combustion-supporting air channel 1-4, which is used to provide initial air supply for green ammonia combustion.

[0034] The outer shell 1-10, the peripheral wind partition wall 1-11, and the venturi tube wall 1-6 are sequentially arranged from the outside to the inside (the present embodiment adopts a coaxial sleeve arrangement), the axial length of the venturi tube wall 1-6 is smaller than the axial length of the outer shell 1-10, the axial length of the peripheral wind partition wall 1-11 is smaller than the axial length of the venturi tube wall 1-6, and one end of the outer shell 1-10, the peripheral wind partition wall 1-11, and the venturi tube wall 1-6 are all flush with the output end of the green ammonia nozzle 1-1; the green ammonia speed reduction and pressurization device 1-3 is fixedly connected to the inner side of the venturi tube wall 1-6 near the output end.

[0035] The cavity between the peripheral wind partition wall 1-11 and the outer shell 1-10 serves as a peripheral wind channel, and the peripheral wind output from the peripheral wind channel is used to protect the green ammonia combustion burner 1 to prevent it from being damaged by the flame; and the spacing of the peripheral wind channels is moderate, which will neither lose the protective effect due to being too small nor affect the flame intensity in the boiler combustion area due to being too large.

[0036] One end of the venturi tube wall 1-6 is flush with the output end of the green ammonia nozzle 1-1, and the other end is inclined toward the housing 1-10, which plays a certain role in guiding the wind direction, so that most of the wind is gathered in the combustion-supporting air channel 1-4 in the center. The cavity between the venturi tube wall 1-6 and the peripheral wind partition wall 1-11 is the air distribution channel 1-2, which is used to assist the combustion-supporting air channel 1-4 in air distribution; the air volume and wind speed of the air distribution channel 1-2 can be adjusted by the damper. The wind speed measuring device 1-12 is arranged in the air distribution channel 1-2 to monitor the hot air volume.

[0037] In practical applications, the surplus electricity from renewable energy sources such as wind power and solar power generation is used to produce green hydrogen through water electrolysis (or other methods), and the green hydrogen produced is input into the green ammonia synthesis device 1-9. The green ammonia produced is transported through the green ammonia pipe 1-7 and respectively input into two green ammonia speed reduction and pressure boosting devices 1-3 through the introduction pipeline 1-5. At this time, the green ammonia flow rate is reduced to 1-8m / s, and the green ammonia pressure is increased. Under the synergistic effect of the green ammonia speed reduction and pressure boosting device 1-3 and the green ammonia nozzle 1-1, the green ammonia is delivered to the boiler combustion zone at a flow rate of 9-160m / s and a certain angle (2-25°).

[0038] Based on the above green ammonia burner nozzle 1, this embodiment also proposes a large wall-type tangential boiler low-temperature low-nitrogen green ammonia coal composite combustion system, which includes four groups arranged along the boiler furnace, such as Figure 2 As shown, each group includes a separate overfire air burner 2 and at least one green ammonia coal composite burner 3 (two green ammonia coal composite burners 3 are provided in this embodiment).

[0039] like Figure 3 As shown, when four groups are arranged along the boiler furnace, the four groups of separate overburnt air burners 2 are arranged at four corners or four walls (four corners are arranged in this embodiment), and the separate overburnt air burners 2 output at the same inclination angle, and their output forms a tangential circle in the center of the boiler combustion area, which can reduce the four-corner tangential circle deviation.

[0040] like Figure 4 As shown, the green ammonia coal composite burner 3 includes in sequence: an upper hot air nozzle 3-1, a first low-nitrogen burner 3-2, a first green ammonia burner nozzle 1, a second low-nitrogen burner 3-2, an intermediate hot air nozzle 3-3, a first plasma or micro-oil ignition burner nozzle 3-4, a second green ammonia burner nozzle 1, a second plasma or micro-oil ignition burner nozzle 3-4, and a lower hot air nozzle 3-5.

[0041] Among them, the two low-nitrogen burners 3-2 and the two plasma or micro-oil ignition burner nozzles 3-4 are all pulverized coal combustion devices, the green ammonia burner nozzle 1 is used to deliver green ammonia and hot air into the boiler combustion zone, and the pulverized coal combustion device is used to deliver pulverized coal and primary hot air into the boiler combustion zone, and the pulverized coal is introduced from the coal mill; the two plasma or micro-oil ignition burner nozzles 3-4 are also used for ignition. The upper hot air nozzle 3-1, the middle hot air nozzle 3-3, and the lower hot air nozzle 3-5 are used to supplement the boiler combustion zone with secondary hot air.

[0042] When the four groups are arranged along the boiler furnace, the four groups of green ammonia coal composite burners 3 are arranged in four walls, such as Figure 4 As shown in (b), the four green ammonia burners located on the same layer output at the same angle, and the combustion-supporting air and green ammonia output form a vortex in the center of the boiler combustion area, and after being ignited, a spiral rising flame is formed. Correspondingly, as Figure 4 As shown in (c), the outputs of the four low-nitrogen burners 3-2 located on the same layer form a vortex in the center of the boiler combustion zone, and after being ignited, a spiral rising flame is formed.

[0043] In actual application, the primary hot air is sent into the boiler combustion zone through the pulverized coal combustion device, and the secondary hot air is sent into the boiler combustion zone through the green ammonia burner nozzle 1, the upper hot air nozzle 3-1, the middle hot air nozzle 3-3, and the lower hot air nozzle 3-5 to supplement the hot air. The air volume and wind speed of the secondary hot air can be adjusted by the damper to achieve two-level air distribution. The low-temperature and low-nitrogen green ammonia coal composite combustion system of the large wall-type tangential boiler adopts plasma or micro-oil ignition burner nozzle 3-4 to ignite under control.

[0044] After the green ammonia enters the combustion zone of the boiler, the flue gas generated by the upstream and surrounding coal powder and green ammonia combustion is sucked in, which increases the ignition heat for the green ammonia combustion. The total excess air coefficient of the main combustion zone is equal to or less than 1 (in the present embodiment, it is in the range of 0.6 to 1), and the entire furnace forms a large combustion flame with flue gas spiraling upward, thereby realizing the state of local low-temperature combustion of the flame and quasi-homogeneous combustion, and ultimately achieving the purpose of reducing the generation of fuel nitrogen during green ammonia combustion.

[0045] Furthermore, there is a certain requirement for the distance between the center of the separate ember burning wind device 2 and the uppermost pulverized coal combustion device to ensure that the green ammonia and pulverized coal can be completely burned at the same time with low nitrogen combustion. In this embodiment, the distance from the center of the separate ember burning wind device 2 to the low nitrogen burner 3-2 located relatively at the uppermost layer in the first green ammonia coal composite burner 3 is ( Figure 1 L1) in the figure is the burning height.

[0046] The system is also equipped with an online monitoring system. A wind speed measuring device 1-12 is set in the air distribution channel 1-2 of the green ammonia burner nozzle 1. The measurement result is transmitted to the control end, which can be a programmable logic controller (PLC), a distributed control system (DCS) or other control systems. The control end controls the opening of valves 1-8 according to the feedback results, and then adjusts the output air volume of the green ammonia burner nozzle 1. A flame monitoring device is set in the combustion system to monitor the ammonia combustion flame and the coal combustion flame online, and the combustion conditions are adjusted online and in real time through PLC, DCS or other control systems to meet the safety production, low pollution emissions and user parameters for the output of the boiler. The operation is simple and effective.

[0047] For large wall-mounted tangential boilers, the amount of entrained smoke (heat) and the mixing of fuel and hot air in the early stage of combustion have a great impact, while the turbulence intensity of the entire furnace combustion area has a great impact in the later stage of combustion. The present invention adjusts the green ammonia jet velocity by controlling the mixing of green ammonia and hot air in two dimensions: space (where to ignite) and time (at what stage to ignite), and adjusting the jet hole area of ​​the jet assembly of the green ammonia burner nozzle and the two types of pulverized coal burner nozzles, thereby changing the jet rigidity; changing the jet angle of the jet assembly to adjust the combustion position, and finally achieving the control of the size of the flame tangential circle formed by the combustion of green ammonia and the size of the flame tangential circle formed by the combustion of pulverized coal, so as to promote rapid ignition, low-temperature combustion and stable combustion of ammonia and coal composite fuels, thereby achieving the purpose of homogeneous combustion of green ammonia and coal, and reducing NO x The generated concentration.

[0048] The purpose of the present invention is to make better use of ammonia, an ideal energy source, and to propose a large-scale wall-type tangentially-circular boiler low-temperature, low-nitrogen green ammonia-coal composite combustion system in combination with the current technical status of coal-fired power units under the dual carbon target. The system uses surplus electricity from renewable energy sources such as wind power and solar power generation to produce green hydrogen and synthesize green ammonia through water electrolysis (or other methods), and then mixes green ammonia with coal to achieve green ammonia-coal composite combustion in the boiler, reducing NO x Generation of.

[0049] Those skilled in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the invention shall be included in the protection scope of the invention.

Claims

1. A green ammonia burner nozzle, whose output end outputs green ammonia to the boiler combustion zone, characterized in that: Including: green ammonia nozzle, air distribution nozzle, green ammonia speed reduction and pressure boosting device, combustion-supporting air channel, introduction pipeline, venturi tube, green ammonia pipe, valve, green ammonia synthesis device, shell, perimeter wind partition wall; One end of the green ammonia pipe is connected to the output end of the green ammonia synthesis device, and the other end is connected to the input ends of the two green ammonia speed reduction and pressure boosting devices through the introduction pipeline. A valve is arranged on the green ammonia pipe; the green ammonia speed reduction and pressure boosting device is a box structure, and a guide plate is arranged inside it. A green ammonia nozzle is fixedly connected to the end face of the output end, and the green ammonia nozzle is a plate with multiple regular through holes; the channel between the two green ammonia speed reduction and pressure boosting devices is a combustion-supporting air channel; The outer shell, the peripheral wind partition wall, and the venturi tube wall are sequentially arranged from the outside to the inside, and the green ammonia speed reduction and pressurization device is fixedly connected to the inner side of the venturi tube wall near the output end; the cavity between the peripheral wind partition wall and the outer shell serves as a peripheral wind channel; one end of the venturi tube wall is flush with the output end of the green ammonia nozzle, and the other end is inclined toward the outer shell, and the cavity between it and the peripheral wind partition wall serves as an air distribution channel.

2. The green ammonia burner nozzle according to claim 1, characterized in that: A damper plate is arranged in the air distribution channel to adjust the air volume and wind speed.

3. The green ammonia burner nozzle according to claim 1, characterized in that: It also includes a wind speed measuring device, which is arranged in the air distribution channel and is used to measure the hot air volume.

4. A large-scale wall-type tangential boiler low-temperature low-nitrogen green ammonia coal composite combustion system, characterized in that: It includes four groups arranged along the boiler, each group includes a separate overfire air burner and at least one green ammonia coal composite burner; the four groups of separate overfire air burners are arranged in four corners or four walls, and the green ammonia coal composite burners are arranged in four walls; The green ammonia coal composite burner comprises in order: an upper hot air nozzle, a first low-nitrogen burner, a first green ammonia burner nozzle according to any one of claims 1 to 3, a second low-nitrogen burner, an intermediate hot air nozzle, a first plasma or micro-oil ignition burner nozzle, a second green ammonia burner nozzle, a second plasma or micro-oil ignition burner nozzle, and a lower hot air nozzle; The two low-nitrogen burners and the two plasma or micro-oil ignition burner nozzles are all pulverized coal combustion devices. The green ammonia burner nozzle is used to deliver green ammonia and hot air into the boiler combustion zone. The pulverized coal combustion device is used to deliver pulverized coal and primary hot air into the boiler combustion zone. The two plasma or micro-oil ignition burner nozzles are also used for ignition. The upper hot air nozzle, the middle hot air nozzle, and the lower hot air nozzle are used to supplement secondary hot air to the boiler combustion zone.

5. The large-scale wall-type tangentially fired boiler low-temperature, low-nitrogen, green ammonia coal composite combustion system according to claim 4 is characterized in that: The upper hot air nozzle, the middle hot air nozzle and the lower hot air nozzle are respectively provided with air door baffles for adjusting the air volume and wind speed of the secondary hot air.

6. The large-scale wall-type tangentially fired boiler low-temperature, low-nitrogen, green ammonia coal composite combustion system according to claim 4 is characterized in that: A flame monitoring device is arranged in the combustion system, and the detection result is fed back to the control system to adjust the combustion conditions in real time; the control system includes a programmable logic controller and a distributed control system.

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