Ammonia-doped hydrogen-doped low-nitrogen coal-fired boiler and working method thereof

Abstract

The invention belongs to the technical field of low-nitrogen combustors, and discloses an ammonia-doped hydrogen-doped low-nitrogen coal-fired boiler and a working method thereof.Each corner of a corner tangential boiler body is provided with a plurality of primary air nozzles in the height direction of a main combustion area, the primary air nozzles are provided with stable combustion teeth, and the stable combustion teeth are used for transversely dividing primary air into a thick part and a thin part; a concentrated phase is arranged inside, and a light phase is arranged outside; an ammonia-doped and hydrogen-doped nozzle is arranged above and / or below each primary air nozzle; and each corner of the four-corner tangential boiler body is provided with an over-fire air nozzle in the over-fire air area. By controlling supply of air, fire coal, ammonia and hydrogen fuel, the combustion process is carried out in stages, and generation of nitric oxide is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of low-nitrogen burners, and in particular relates to an ammonia-doped, hydrogen-doped and low-nitrogen coal-fired boiler and a working method thereof. Background Art

[0002] Ammonia-hydrogen combustion refers to the process of mixing ammonia (NH3), hydrogen (H2) and fuel (such as coal, natural gas, etc.) for combustion. This combustion method can reduce the use of fossil fuels, improve combustion efficiency and reduce carbon emissions. Although ammonia and hydrogen can directly replace fossil fuels and achieve zero carbon emissions, ammonia and hydrogen also have their own disadvantages: ammonia is toxic, and special facilities are required for storage and transportation. Nitrogen oxides are easily produced during ammonia combustion, which are toxic and harmful gases; hydrogen is a very light gas that is easy to escape during storage and transportation. Hydrogen itself is flammable and explosive, and there are certain dangers during use. In addition, it takes a lot of energy to produce hydrogen from fossil fuels.

[0003] When ammonia and hydrogen are mixed and burned, the flame speed of ammonia is slow and the flame temperature is low, so it is usually necessary to add a combustion aid to improve the combustion efficiency. The addition of hydrogen can increase the combustion speed and temperature. The rapid combustion characteristics of hydrogen can drive the combustion of ammonia, thereby improving the overall combustion efficiency.

[0004] Ammonia and hydrogen can reduce carbon dioxide emissions by replacing part of the coal, which helps achieve the carbon reduction target. However, when the hydrogen blending ratio exceeds 0.8, the flame temperature rises, the local heat release increases, and the increase in NOx (i.e. nitrogen oxide) emissions increases. When the ammonia blending ratio is below 20%, NOx emissions decrease, and when the ammonia blending ratio is between 20% and 60%, NOx emissions increase. Therefore, how to achieve carbon emission reduction while effectively controlling the generation of nitrogen oxides when blending ammonia and hydrogen in coal-fired boilers is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an ammonia-hydrogen-doped low-nitrogen coal-fired boiler and a working method thereof, which can effectively control the generation of nitrogen oxides while performing ammonia-doped hydrogen combustion in the coal-fired boiler to achieve carbon emission reduction.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A coal-fired boiler with low nitrogen content and doped with ammonia, hydrogen and water, comprises a four-corner rounded boiler body, each corner of the four-corner rounded boiler body is provided with a plurality of primary air nozzles in the height direction in the main combustion area, and the primary air nozzles are provided with combustion stabilizing teeth, and the combustion stabilizing teeth are used to divide the primary air into two streams, dense and light, with the dense phase inside and the light phase outside; ammonia and hydrogen doping nozzles are provided above and / or below each primary air nozzle; Each corner of the four-corner rounded boiler body is provided with a burnout air nozzle in the burnout air area.

[0007] Preferably, the several primary air nozzles include a first primary air nozzle, a second primary air nozzle, a third primary air nozzle, a fourth primary air nozzle and a fifth primary air nozzle, and the first primary air nozzle, the second primary air nozzle, the third primary air nozzle, the fourth primary air nozzle and the fifth primary air nozzle are distributed in sequence from the bottom to the top of the main combustion area.

[0008] Preferably, the ammonia-doped hydrogen-doped nozzles include a first ammonia-doped hydrogen-doped nozzle, a second ammonia-doped hydrogen-doped nozzle, a third ammonia-doped hydrogen-doped nozzle, a fourth ammonia-doped hydrogen-doped nozzle, a fifth ammonia-doped hydrogen-doped nozzle and a sixth ammonia-doped hydrogen-doped nozzle; The first ammonia and hydrogen mixing nozzle is arranged below the first primary air nozzle, the second ammonia and hydrogen mixing nozzle is arranged above the second primary air nozzle, the third ammonia and hydrogen mixing nozzle is arranged below the third primary air nozzle and above the second ammonia and hydrogen mixing nozzle, the fourth ammonia and hydrogen mixing nozzle is arranged above the third primary air nozzle, the fifth ammonia and hydrogen mixing nozzle is arranged below the fourth primary air nozzle and above the fourth ammonia and hydrogen mixing nozzle, and the sixth ammonia and hydrogen mixing nozzle is arranged above the fifth primary air nozzle.

[0009] Preferably, a large first and second air nozzle is provided at the bottom of each corner of the four-corner cut-round boiler body below the first ammonia and hydrogen doping nozzle, and the large first and second air nozzle serves as bottom supporting wind.

[0010] Preferably, a second large secondary air nozzle is provided between the first primary air nozzle and the second primary air nozzle at each corner of the four-corner cut-circle boiler body, and the second large secondary air nozzle serves as auxiliary air for boiler combustion.

[0011] Preferably, a third large secondary air nozzle is provided between the fourth primary air nozzle and the fifth primary air nozzle at each corner of the four-corner cut-circle boiler body, and the third large secondary air nozzle serves as auxiliary air for boiler combustion.

[0012] Preferably, a fourth large secondary air nozzle is provided above the sixth ammonia and hydrogen doping nozzle at each corner of the four-corner cut-circle boiler body, and the fourth large secondary air nozzle serves as the burnout air of the main combustion zone.

[0013] Preferably, a first small secondary air nozzle is provided between the second ammonia-hydrogen nozzle and the third ammonia-hydrogen nozzle at each corner of the four-corner cut-circle boiler body, and a second small secondary air nozzle is provided between the fourth ammonia-hydrogen nozzle and the fifth ammonia-hydrogen nozzle. The first small secondary air nozzle and the second small secondary air nozzle are used to supplement the required oxygen for the main combustion area.

[0014] Preferably, each corner of the four-corner tangentially circular boiler body is provided with a plurality of burnout air nozzles in the burnout air area, and the plurality of burnout air nozzles can swing vertically and horizontally.

[0015] The working method of the coal-fired boiler with ammonia, hydrogen and low nitrogen as described above of the present invention comprises: When the coal-fired boiler is burning, the pulverized coal enters the main combustion area through the pulverized coal fuel outlet of the primary air nozzle, the ammonia enters the main combustion area through the ammonia fuel outlet of the ammonia and hydrogen nozzle, and the hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder of the ammonia and hydrogen nozzle; When a coal-fired boiler is burning, in the main combustion area, all the fuel and most of the air are introduced to make the fuel burn under oxygen-deficient conditions to reduce the generation of nitrogen oxides. Among them, the primary air nozzle divides the primary air horizontally into two streams, thick and thin. The thick phase is inside, the combustion tangent circle is relatively small, and it is closer to the center of the flame, and the thin phase is outside, and the combustion tangent circle is relatively large. The flame temperature in the thick phase is relatively high, and the oxygen content is relatively low, so as to reduce the generation of nitrogen oxides. The temperature outside the phase is relatively low, and the oxygen content is relatively high, so as to reduce the generation of nitrogen oxides. At the same time, ammonia and hydrogen are introduced through ammonia and hydrogen mixing nozzles. The flame speed of ammonia is relatively slow, and the flame temperature is relatively low. It is arranged outside the primary air nozzle to delay the mixing of coal powder and oxygen, thereby reducing the generation of nitrogen oxides. The addition of hydrogen can increase the combustion speed and temperature, and use the rapid combustion of hydrogen to drive the combustion of ammonia and reduce the nitrogen oxides in the early stage of coal powder combustion. In the overburnt air area, the remaining air is introduced through the overburnt air nozzle. The flame temperature here is relatively low, which reduces part of the nitrogen oxides produced in the main combustion area and further reduces the generation of nitrogen oxides.

[0016] The present invention has the following beneficial effects: Compared with the existing burner arrangement structure, the coal-fired boiler with ammonia and hydrogen blended and low nitrogen content and its working method of the present invention have the advantage of controlling the supply of air and coal, ammonia and hydrogen fuels to make the combustion process proceed in stages, effectively reducing the generation of nitrogen oxides. First, in the main combustion area, all the fuel and most of the air are introduced through the nozzle to reduce the local oxygen concentration and temperature, so that the fuel burns under oxygen-deficient conditions, forming a reducing atmosphere in the main combustion area, effectively reducing the generation of nitrogen oxides. Among them, the primary air nozzle and the combustion stabilizing teeth divide the primary air horizontally into two streams, thick and thin. The thick phase is inside, the combustion tangent circle is smaller, and it is closer to the center of the flame, and the thin phase is outside, and the combustion tangent circle is larger. The flame temperature in the thick phase is higher, but the oxygen is less, so the nitrogen oxides generated are less, while the temperature outside the thin phase is lower, the oxygen is more, and the nitrogen oxides generated are also less. At the same time, ammonia and hydrogen are introduced through the ammonia and hydrogen nozzles. Ammonia has a slower flame speed and a lower flame temperature. It is arranged outside the primary air nozzle, which can delay the mixing of coal powder and oxygen and reduce the generation of nitrogen oxides. The addition of hydrogen can increase the combustion speed and temperature. The rapid combustion characteristics of hydrogen can drive the combustion of ammonia and reduce the nitrogen oxides in the early stage of coal powder combustion. Secondly, after the main combustion process, the remaining air is introduced through the burnout air nozzle in the burnout zone. The flame temperature here is lower, which can reduce some of the nitrogen oxides generated in the main combustion zone and further reduce the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic structural diagram of the coal-fired boiler with mixed ammonia, mixed hydrogen and low nitrogen according to the present invention.

[0019] Figure 2 The present invention is a schematic diagram of the structure of the ammonia-hydrogen-doped nozzle of the low-nitrogen coal-fired boiler.

[0020] Figure 3 The present invention is a schematic diagram of the primary air nozzle structure of the coal-fired boiler with ammonia, hydrogen and low nitrogen content.

[0021] In the figure: 101-first large secondary air nozzle, 102-second large secondary air nozzle, 103-third large secondary air nozzle, 104-fourth large secondary air nozzle, 201-first ammonia and hydrogen nozzle, 202-second ammonia and hydrogen nozzle, 203-third ammonia and hydrogen nozzle, 204-fourth ammonia and hydrogen nozzle, 205-fifth ammonia and hydrogen nozzle, 206-sixth ammonia and hydrogen nozzle, 2-1-hydrogen fuel outlet cylinder , 2-2-ammonia fuel outlet, 301-first primary air nozzle, 302-first primary air nozzle, 303-first primary air nozzle, 304-first primary air nozzle, 305-first primary air nozzle, 3-1-coal powder fuel outlet, 3-2-stable combustion teeth, 3-3-gap air outlet, 401-first secondary air small nozzle, 402-second secondary air small nozzle, 5-burnout air nozzle, 6-four-corner cut-circle boiler body. DETAILED DESCRIPTION

[0022] According to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structures and implementations. Therefore, the following specific implementation methods and drawings are only examples of the technical solution of the present invention and should not be regarded as the entirety of the present invention or the limitation of its technical solution.

[0023] See also Figure 1-Figure 3 The coal-fired boiler with ammonia, hydrogen and low nitrogen in this embodiment includes a four-corner cut-round boiler body 6, and each corner of the four-corner cut-round boiler body 6 is provided with a plurality of primary air nozzles in the height direction in the main combustion area, and the primary air nozzles are provided with stabilizing teeth 3-2, and the stabilizing teeth 3-2 are used to divide the primary air horizontally into two streams, the dense phase is inside and the light phase is outside; an ammonia and hydrogen nozzle is provided above and / or below each primary air nozzle; each corner of the four-corner cut-round boiler body 6 is provided with a burnout air nozzle 5 in the burnout air area.

[0024] The working method of the coal-fired boiler with ammonia, hydrogen and low nitrogen in the above embodiment of the present invention includes the following process: When the coal-fired boiler is burning, the pulverized coal enters the main combustion area through the pulverized coal fuel outlet 3-1 of the primary air nozzle, ammonia enters the main combustion area through the ammonia fuel outlet 2-2 in the ammonia and hydrogen nozzle, and hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder 2-1 of the ammonia and hydrogen nozzle; In the main combustion area, by introducing all the fuel and most of the air, the fuel is burned under oxygen-deficient conditions to reduce the generation of nitrogen oxides; the primary air nozzle divides the primary air horizontally into two streams, a dense phase inside, with a relatively small combustion tangent circle and closer to the flame center, and a light phase outside, with a relatively large combustion tangent circle; the flame temperature in the dense phase is relatively high and the oxygen content is relatively low to reduce the generation of nitrogen oxides, while the temperature outside the phase is relatively low and the oxygen content is relatively high to reduce the generation of nitrogen oxides; at the same time, ammonia and hydrogen are introduced through ammonia and hydrogen mixing nozzles, the flame speed of ammonia is relatively slow and the flame temperature is relatively low, and they are arranged outside the primary air nozzle to delay the mixing of coal powder and oxygen, thereby reducing the generation of nitrogen oxides; the addition of hydrogen can increase the combustion speed and temperature, and use the rapid combustion of hydrogen to drive the combustion of ammonia and reduce the nitrogen oxides in the early stage of coal powder combustion; In the overburnt air area, the remaining air is introduced through the overburnt air nozzle 5. The flame temperature here is relatively low, which reduces part of the nitrogen oxides produced in the main combustion area and further reduces the generation of nitrogen oxides.

[0025] As a preferred embodiment of the present invention, see Figure 1 In the present embodiment, a total of five primary air nozzles are provided, including a first primary air nozzle 301, a second primary air nozzle 302, a third primary air nozzle 303, a fourth primary air nozzle 304 and a fifth primary air nozzle 305. The first primary air nozzle 301, the second primary air nozzle 302, the third primary air nozzle 303, the fourth primary air nozzle 304 and the fifth primary air nozzle 305 are distributed in sequence from the bottom to the top of the main combustion area.

[0026] As a preferred embodiment of the present invention, on the basis of the above embodiment, in this embodiment, six ammonia-doped hydrogen-doped nozzles are provided, specifically including a first ammonia-doped hydrogen-doped nozzle 201, a second ammonia-doped hydrogen-doped nozzle 202, a third ammonia-doped hydrogen-doped nozzle 203, a fourth ammonia-doped hydrogen-doped nozzle 204, a fifth ammonia-doped hydrogen-doped nozzle 205 and a sixth ammonia-doped hydrogen-doped nozzle 206; See also Figure 1, wherein the first ammonia and hydrogen doping nozzle 201 is arranged below the first primary air nozzle 301, the second ammonia and hydrogen doping nozzle 202 is arranged above the second primary air nozzle 302, the third ammonia and hydrogen doping nozzle 203 is arranged below the third primary air nozzle 303 and above the second ammonia and hydrogen doping nozzle 202, the fourth ammonia and hydrogen doping nozzle 204 is arranged above the third primary air nozzle 303, the fifth ammonia and hydrogen doping nozzle 205 is arranged below the fourth primary air nozzle 304 and above the fourth ammonia and hydrogen doping nozzle 204, and the sixth ammonia and hydrogen doping nozzle 206 is arranged above the fifth primary air nozzle 305. Among them, the ammonia-hydrogen blending nozzle has a hydrogen fuel outlet cylinder 2-1 and an ammonia fuel outlet 2-2. The flame speed of ammonia is slow and the flame temperature is low. The ammonia-hydrogen blending nozzle is arranged above and / or below the primary air nozzle, which can delay the mixing of coal powder and oxygen and reduce the generation of nitrogen oxides. At the same time, hydrogen can be added through the hydrogen fuel outlet cylinder 2-1. The addition of hydrogen can increase the combustion speed and temperature. The rapid combustion characteristics of hydrogen can drive the combustion of ammonia and reduce nitrogen oxides in the early stage of coal powder combustion.

[0027] As a preferred embodiment of the present invention, based on the above embodiment, in this embodiment, the bottom of each corner of the four-corner cut-circle boiler body 6 is provided with a first large secondary air nozzle 101 below the first ammonia and hydrogen nozzle 201, and the first large secondary air nozzle 101 serves as bottom air. The use of a large secondary air nozzle for the bottom air at the bottom layer can increase the secondary air flow rate here and effectively reduce the generation of slag.

[0028] As a preferred embodiment of the present invention, based on the above embodiment, in this embodiment, each corner of the four-corner cut-circle boiler body 6 is provided with a second large secondary air nozzle 102 between the first primary air nozzle 301 and the second primary air nozzle 302, and the second large secondary air nozzle 102 serves as boiler combustion auxiliary air. The boiler combustion auxiliary air between the two primary air nozzles at the bottom layer and between the two primary air nozzles at the top layer adopts a large secondary air nozzle, and the larger secondary air flow rate here can ensure the stability of combustion in the main combustion area of ​​the boiler.

[0029] As a preferred embodiment of the present invention, based on the above embodiment, in this embodiment, each corner of the four-corner tangential boiler body 6 is provided with a third secondary air large nozzle 103 between the fourth primary air nozzle 304 and the fifth primary air nozzle 305, and the third secondary air large nozzle 103 is used as boiler combustion auxiliary air. The use of a secondary air large nozzle for the top burnout air in the main combustion zone can increase the secondary air flow rate here and effectively reduce the generation of fly ash.

[0030] As a preferred implementation scheme of the present invention, based on the above-mentioned embodiments, in this embodiment, each corner of the four-corner cut-circle boiler body 6 is provided with a fourth large secondary air nozzle 104 above the sixth ammonia and hydrogen doping nozzle 206, and the fourth large secondary air nozzle 104 serves as the burnout air of the main combustion zone.

[0031] As a preferred embodiment of the present invention, based on the above embodiment, in this embodiment, each corner of the four-corner cut-circle boiler body 6 is provided with a first secondary air small nozzle 401 between the second ammonia and hydrogen nozzle 202 and the third ammonia and hydrogen nozzle 203, and a second secondary air small nozzle 402 is provided between the fourth ammonia and hydrogen nozzle 204 and the fifth ammonia and hydrogen nozzle 205. The first secondary air small nozzle 401 and the second secondary air small nozzle 402 are used to supplement the required oxygen for the main combustion area. In this embodiment, the secondary air small nozzles are all located between the two ammonia and hydrogen nozzles, and also between the two primary air nozzles. The secondary air small nozzles can be used to supplement the required oxygen for the main combustion area.

[0032] As a preferred embodiment of the present invention, based on the above embodiment, in this embodiment, each corner of the four-corner tangential boiler body 6 is provided with a plurality of overburnt air nozzles 5 in the overburnt air area, and the plurality of overburnt air nozzles 5 can be swung vertically and horizontally according to the combustion adjustment requirements. The overburnt air nozzles can be used to feed the residual air of the secondary air into the furnace of the four-corner tangential boiler body 6. Since the flame temperature in the overburnt air area is relatively low, part of the nitrogen oxides generated in the main combustion area can be reduced, further reducing the generation of nitrogen oxides.

[0033] Example Reference Figure 1-Figure 3 The coal-fired boiler with ammonia, hydrogen and low nitrogen in this embodiment includes a four-corner tangential boiler body 6, and a plurality of large secondary air nozzles, ammonia and hydrogen nozzles, primary air nozzles, small secondary air nozzles and burnout air nozzles 5 are arranged at each corner of the four-corner tangential boiler body 6. The specific structure is as follows: In this embodiment, a total of five primary air nozzles are provided, which are respectively denoted as the first primary air nozzle 301, the second primary air nozzle 302, the third primary air nozzle 303, the fourth primary air nozzle 304 and the fifth primary air nozzle 305. The first primary air nozzle 301, the second primary air nozzle 302, the third primary air nozzle 303, the fourth primary air nozzle 304 and the fifth primary air nozzle 305 are distributed in sequence from the bottom to the top of the main combustion area. A total of six ammonia-hydrogen-doped nozzles are provided, which are respectively recorded as the first ammonia-hydrogen-doped nozzle 201, the second ammonia-hydrogen-doped nozzle 202, the third ammonia-hydrogen-doped nozzle 203, the fourth ammonia-hydrogen-doped nozzle 204, the fifth ammonia-hydrogen-doped nozzle 205 and the sixth ammonia-hydrogen-doped nozzle 206; four large secondary air nozzles are respectively recorded as the first large secondary air nozzle 101, the second large secondary air nozzle 102, the third large secondary air nozzle 103 and the fourth large secondary air nozzle 104, two small secondary air nozzles are respectively recorded as the first small secondary air nozzle 401 and the second small secondary air nozzle 402, and four burnout air nozzles 5 are provided.

[0034] Specifically, among the five large secondary air nozzles, the first large secondary air nozzle 101 is arranged at the bottom layer of the four-corner cut-circle boiler body 6 as bottom air, the fourth large secondary air nozzle 104 is arranged at the top layer of the main combustion area of ​​the boiler as the burnout air of the main combustion area, the second large secondary air nozzle 102 is arranged between the two primary air nozzles at the bottom layer (i.e., the first primary air nozzle 301 and the second primary air nozzle 302) as boiler combustion auxiliary air, and the third large secondary air nozzle 103 is arranged between the two primary air nozzles at the top layer (i.e., the fourth primary air nozzle 304 and the fifth primary air nozzle 305) and also as boiler combustion auxiliary air. The use of large secondary air nozzles for the bottom air at the bottom layer can increase the secondary air flow rate here and effectively reduce the generation of slag. The use of large secondary air nozzles for the burnout air at the top layer of the main combustion area can increase the secondary air flow rate here and effectively reduce the generation of fly ash. The boiler combustion auxiliary air between the two primary air nozzles on the bottom layer and between the two primary air nozzles on the top layer adopts large secondary air nozzles. The larger secondary air flow rate here can ensure the stability of combustion in the main combustion area of ​​the boiler.

[0035] Among the six ammonia-hydrogen-doped nozzles, the first ammonia-hydrogen-doped nozzle 201 is arranged between the first primary air nozzle 301 and the first secondary air nozzle 101, the second ammonia-hydrogen-doped nozzle 202 is arranged above the second primary air nozzle 302, the third ammonia-hydrogen-doped nozzle 203 is arranged below the third ammonia-hydrogen-doped nozzle 203 and above the second ammonia-hydrogen-doped nozzle 202, the fourth ammonia-hydrogen-doped nozzle 204 is arranged above the third ammonia-hydrogen-doped nozzle 203, the fifth ammonia-hydrogen-doped nozzle 205 is arranged below the fourth primary air nozzle 304 and above the fourth ammonia-hydrogen-doped nozzle 204, and the sixth ammonia-hydrogen-doped nozzle 206 is arranged between the fifth primary air nozzle 305 and the fourth secondary air nozzle 104; all the ammonia-hydrogen-doped nozzles are provided with a hydrogen fuel outlet cylinder 2-1, and both sides of the hydrogen fuel outlet cylinder 2-1 are provided with ammonia fuel outlets 2-2. The flame speed of ammonia is slower and the flame temperature is lower. The ammonia and hydrogen nozzles are arranged above and below the primary air nozzles, which can delay the mixing of coal powder and oxygen and reduce the formation of nitrogen oxides. At the same time, the addition of hydrogen can increase the combustion speed and temperature. The rapid combustion characteristics of hydrogen can drive the combustion of ammonia and reduce nitrogen oxides in the early stage of coal powder combustion.

[0036] Of the two small secondary air nozzles, the first small secondary air nozzle 401 is arranged between the second ammonia and hydrogen nozzle 202 and the third ammonia and hydrogen nozzle 203, and the second small secondary air nozzle 402 is arranged between the fourth ammonia and hydrogen nozzle 204 and the fifth ammonia and hydrogen nozzle 205. It can be seen that the two small secondary air nozzles are arranged between the two ammonia and hydrogen nozzles 2 and between the two primary air nozzles 3. The small secondary air nozzles can supplement the required oxygen for the main combustion area.

[0037] It can be seen that in this embodiment, the four primary air nozzles are separated by large secondary air nozzles, ammonia and hydrogen nozzles or small secondary air nozzles, and all primary air nozzles are provided with combustion stabilizing teeth 3-2. The primary air nozzles and combustion stabilizing teeth divide the primary air horizontally into two streams, dense phase inside, with a smaller combustion tangent circle, closer to the center of the flame, and the light phase outside, with a larger combustion tangent circle. The flame temperature in the dense phase is higher, but the oxygen is less, so the nitrogen oxides generated are less, while the temperature outside the light phase is lower, the oxygen is more, and the nitrogen oxides generated are also less.

[0038] Four overburnt air nozzles 5 are arranged adjacent to each other in the overburnt area above the main combustion area, and the overburnt air nozzles 5 can swing vertically and horizontally according to the combustion adjustment needs. The overburnt air nozzles supply the residual air of the secondary air, where the flame temperature is relatively low, which can reduce part of the nitrogen oxides generated in the main combustion area, further reducing the generation of nitrogen oxides.

[0039] The working method of the coal-fired boiler with ammonia, hydrogen and low nitrogen in this embodiment includes the following process: When the coal-fired boiler is burning, the pulverized coal enters the main combustion area through the pulverized coal fuel outlet 3-1 of the primary air nozzle, ammonia enters the main combustion area through the ammonia fuel outlet 2-2 in the ammonia and hydrogen nozzle 2, hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder 2-1, the secondary air enters the main combustion area through the secondary air large nozzle and the secondary air small nozzle, the gap air enters the main combustion area through the gap air outlet 3-3 of the primary air nozzle, and the burnout air enters the burnout air area through the burnout air nozzle 5. The primary air velocity entering the furnace is 20~25m / s, the secondary air velocity is 45~55m / s, the ammonia velocity is 60~80m / s, the hydrogen velocity is 80~100m / s, and the burnout air and gap air have the same velocity as the secondary air.

[0040] When the boiler is burning, in the main combustion area, by feeding all the fuel and most of the air, the fuel is burned under oxygen-deficient conditions, effectively reducing the generation of nitrogen oxides. The primary air nozzle divides the primary air horizontally into two streams, the dense phase inside, with a smaller combustion tangent circle and closer to the center of the flame, and the light phase outside, with a larger combustion tangent circle. The flame temperature in the dense phase is higher, but there is less oxygen, so less nitrogen oxides are generated, while the temperature outside the light phase is lower, with more oxygen, and less nitrogen oxides are generated. At the same time, ammonia and hydrogen are fed into the ammonia and hydrogen nozzles. The flame speed of ammonia is slower and the flame temperature is lower. It is arranged outside the primary air nozzle, which can delay the mixing of coal powder and oxygen and reduce the generation of nitrogen oxides. The addition of hydrogen can increase the combustion speed and temperature. The rapid combustion characteristics of hydrogen can drive the combustion of ammonia and reduce nitrogen oxides in the early stage of coal powder combustion.

[0041] In the overburnt air area, the remaining air is introduced through the overburnt air nozzle. The flame temperature here is lower, which reduces part of the nitrogen oxides produced in the main combustion area and further reduces the generation of nitrogen oxides.

[0042] In this embodiment, the airflow sprayed by the four-corner burners of the coal-fired boiler forms four-corner tangential circular combustion, and a rotating layer of combustion airflow is formed in both the vertical direction and the horizontal direction.

[0043] It can be seen from the above that the present invention can effectively reduce the generation of nitrogen oxides by controlling the supply of air and coal, ammonia and hydrogen fuels so that the combustion process is carried out in stages.

[0044] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the present invention. The scope of patent protection shall be determined by the submitted claims.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A coal-fired boiler with ammonia, hydrogen and low nitrogen content, characterized in that: It comprises a four-corner tangential boiler body (6), each corner of the four-corner tangential boiler body (6) is provided with a plurality of primary air nozzles in the height direction of the main combustion area, and the primary air nozzles are provided with combustion stabilizing teeth (3-2), and the combustion stabilizing teeth (3-2) are used to divide the primary air into two streams, a dense phase inside and a light phase outside; an ammonia and hydrogen mixing nozzle is provided above and / or below each primary air nozzle; Each corner of the four-corner tangential boiler body (6) is provided with a burnout air nozzle (5) in the burnout air area.

2. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 1, characterized in that: The plurality of primary air nozzles include a first primary air nozzle (301), a second primary air nozzle (302), a third primary air nozzle (303), a fourth primary air nozzle (304) and a fifth primary air nozzle (305), wherein the first primary air nozzle (301), the second primary air nozzle (302), the third primary air nozzle (303), the fourth primary air nozzle (304) and the fifth primary air nozzle (305) are distributed in sequence from the bottom to the top of the main combustion area.

3. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 2, characterized in that: The ammonia-doped hydrogen-doped nozzles include a first ammonia-doped hydrogen-doped nozzle (201), a second ammonia-doped hydrogen-doped nozzle (202), a third ammonia-doped hydrogen-doped nozzle (203), a fourth ammonia-doped hydrogen-doped nozzle (204), a fifth ammonia-doped hydrogen-doped nozzle (205) and a sixth ammonia-doped hydrogen-doped nozzle (206); The first ammonia-hydrogen doping nozzle (201) is arranged below the first primary air nozzle (301), the second ammonia-hydrogen doping nozzle (202) is arranged above the second primary air nozzle (302), the third ammonia-hydrogen doping nozzle (203) is arranged below the third primary air nozzle (303) and above the second ammonia-hydrogen doping nozzle (202), the fourth ammonia-hydrogen doping nozzle (204) is arranged above the third primary air nozzle (303), the fifth ammonia-hydrogen doping nozzle (205) is arranged below the fourth primary air nozzle (304) and above the fourth ammonia-hydrogen doping nozzle (204), and the sixth ammonia-hydrogen doping nozzle (206) is arranged above the fifth primary air nozzle (305).

4. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 3, characterized in that: A first large secondary air nozzle (101) is provided at the bottom of each corner of the four-corner tangential boiler body (6) below the first ammonia and hydrogen doping nozzle (201), and the first large secondary air nozzle (101) serves as bottom supporting air.

5. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 3, characterized in that: A second large secondary air nozzle (102) is provided between the first primary air nozzle (301) and the second primary air nozzle (302) at each corner of the four-corner tangential boiler body (6), and the second large secondary air nozzle (102) serves as boiler combustion auxiliary air.

6. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 3, characterized in that: A third large secondary air nozzle (103) is provided between a fourth primary air nozzle (304) and a fifth primary air nozzle (305) at each corner of the four-corner tangential boiler body (6), and the third large secondary air nozzle (103) serves as boiler combustion auxiliary air.

7. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 3, characterized in that: A fourth large secondary air nozzle (104) is provided above the sixth ammonia and hydrogen doping nozzle (206) at each corner of the four-corner tangentially circular boiler body (6), and the fourth large secondary air nozzle (104) serves as burnout air for the main combustion zone.

8. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 3, characterized in that: A first small secondary air nozzle (401) is provided at each corner of the four-corner cut-circle boiler body (6) between the second ammonia-hydrogen doping nozzle (202) and the third ammonia-hydrogen doping nozzle (203), and a second small secondary air nozzle (402) is provided between the fourth ammonia-hydrogen doping nozzle (204) and the fifth ammonia-hydrogen doping nozzle (205). The first small secondary air nozzle (401) and the second small secondary air nozzle (402) are used to supplement the oxygen required for the main combustion area.

9. The coal-fired boiler with ammonia, hydrogen and low nitrogen content according to claim 1, characterized in that: Each corner of the four-corner tangential boiler body (6) is provided with a plurality of overburnt air nozzles (5) in the overburnt air area, and the plurality of overburnt air nozzles (5) can swing vertically and horizontally.

10. The operating method of a coal-fired boiler with ammonia, hydrogen and low nitrogen content according to any one of claims 1 to 9, characterized in that: include: When the coal-fired boiler is burning, the pulverized coal enters the main combustion area through the pulverized coal fuel outlet (3-1) of the primary air nozzle, ammonia enters the main combustion area through the ammonia fuel outlet (2-2) of the ammonia and hydrogen nozzle, and hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder (2-1) of the ammonia and hydrogen nozzle; In the main combustion area, by introducing all the fuel and most of the air, the fuel is burned under oxygen-deficient conditions to reduce the generation of nitrogen oxides; the primary air nozzle divides the primary air horizontally into two streams, a dense phase inside, with a relatively small combustion tangent circle and closer to the flame center, and a light phase outside, with a relatively large combustion tangent circle; the flame temperature in the dense phase is relatively high and the oxygen content is relatively low to reduce the generation of nitrogen oxides, while the temperature outside the phase is relatively low and the oxygen content is relatively high to reduce the generation of nitrogen oxides; at the same time, ammonia and hydrogen are introduced through ammonia and hydrogen mixing nozzles, the flame speed of ammonia is relatively slow and the flame temperature is relatively low, and they are arranged outside the primary air nozzle to delay the mixing of coal powder and oxygen, thereby reducing the generation of nitrogen oxides; the addition of hydrogen can increase the combustion speed and temperature, and use the rapid combustion of hydrogen to drive the combustion of ammonia and reduce the nitrogen oxides in the early stage of coal powder combustion; In the overburnt air area, excess air is introduced through the overburnt air nozzle (5). The flame temperature here is relatively low, which reduces part of the nitrogen oxides generated in the main combustion area, further reducing the generation of nitrogen oxides.

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