A low-nitrogen coal-fired boiler doped with ammonia and hydrogen and a working method thereof

Abstract

The present application belongs to the technical field of low-nitrogen combustor, and discloses a coal-fired boiler with low-nitrogen and ammonia-hydrogen mixing and a working method thereof. A plurality of primary air nozzles are arranged at each corner of the four-corner tangential boiler body in the height direction in the main combustion area. A stable combustion tooth is arranged on the primary air nozzle. The stable combustion tooth is used for horizontally dividing the primary air into two streams with different densities, and the dense phase is inside and the dilute phase is outside. An ammonia-hydrogen mixing nozzle is arranged above and / or below each primary air nozzle. A burnout air nozzle is arranged at each corner of the four-corner tangential boiler body in the burnout air area. The present application controls the supply of air, coal, ammonia and hydrogen fuel, so that the combustion process is carried out in stages, and the generation of nitrogen oxides is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of low-nitrogen burners, and particularly relates to a coal-fired boiler with low-nitrogen ammonia-hydrogen blending and a working method thereof. BACKGROUND

[0002] Ammonia-hydrogen blending combustion refers to the process of mixing ammonia (NH3) and hydrogen (H2) with 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 to 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 produced during ammonia combustion, which are toxic and harmful gases. Hydrogen is a very light gas that can easily escape during storage and transportation. Hydrogen itself is flammable and explosive, and its use is dangerous. Producing hydrogen from fossil fuels requires a large amount of energy.

[0003] During ammonia-hydrogen blending combustion, the flame speed of ammonia is slow, and the flame temperature is low, so it is usually necessary to add combustion improvers to improve combustion efficiency. The addition of hydrogen can increase the combustion speed and temperature, and the rapid combustion characteristics of hydrogen can drive the combustion of ammonia, thereby improving the overall combustion efficiency.

[0004] Ammonia-hydrogen blending can replace part of the coal to reduce carbon dioxide emissions, which helps to achieve carbon emission reduction targets. However, when the hydrogen blending ratio exceeds 0.8, the flame temperature rises, the local heat release increases, and the NOx (nitrogen oxides) emission increases significantly. 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 effectively control the generation of nitrogen oxides while achieving carbon emission reduction during ammonia-hydrogen blending combustion in coal-fired boilers is a technical problem that needs to be solved in the field. SUMMARY

[0005] To solve the problems in the prior art, the purpose of the present application is to provide a coal-fired boiler with low-nitrogen ammonia-hydrogen blending and a working method thereof, which can effectively control the generation of nitrogen oxides while achieving carbon emission reduction during ammonia-hydrogen blending combustion in coal-fired boilers.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0007] A coal-fired boiler with low-nitrogen ammonia-hydrogen blending, comprising a four-corner tangential boiler body, a plurality of primary air nozzles are arranged in the height direction at each corner of the four-corner tangential boiler body in the main combustion area, a stable combustion tooth is arranged on each primary air nozzle, the stable combustion tooth is used to divide the primary air into two streams of different densities, with the dense phase inside and the light phase outside. An ammonia-hydrogen blending nozzle is arranged above and / or below each primary air nozzle.

[0008] Each corner of the tangentially-fired boiler body is provided with an overfire air nozzle in the overfire air region.

[0009] Preferably, the plurality of primary air nozzles comprises 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 sequentially distributed from the bottom to the top of the main combustion region.

[0010] Preferably, the ammonia-hydrogen injection nozzles comprise a first ammonia-hydrogen injection nozzle, a second ammonia-hydrogen injection nozzle, a third ammonia-hydrogen injection nozzle, a fourth ammonia-hydrogen injection nozzle, a fifth ammonia-hydrogen injection nozzle, and a sixth ammonia-hydrogen injection nozzle.

[0011] The first ammonia-hydrogen injection nozzle is arranged below the first primary air nozzle, the second ammonia-hydrogen injection nozzle is arranged above the second primary air nozzle, the third ammonia-hydrogen injection nozzle is arranged below the third primary air nozzle and above the second ammonia-hydrogen injection nozzle, the fourth ammonia-hydrogen injection nozzle is arranged above the third primary air nozzle, the fifth ammonia-hydrogen injection nozzle is arranged below the fourth primary air nozzle and above the fourth ammonia-hydrogen injection nozzle, and the sixth ammonia-hydrogen injection nozzle is arranged above the fifth primary air nozzle.

[0012] Preferably, the bottom of each corner of the tangentially-fired boiler body is provided with a first secondary air large nozzle below the first ammonia-hydrogen injection nozzle, and the first secondary air large nozzle serves as a bottom support air.

[0013] Preferably, each corner of the tangentially-fired boiler body is provided with a second secondary air large nozzle between the first primary air nozzle and the second primary air nozzle, and the second secondary air large nozzle serves as a boiler combustion auxiliary air.

[0014] Preferably, each corner of the tangentially-fired boiler body is provided with a third secondary air large nozzle between the fourth primary air nozzle and the fifth primary air nozzle, and the third secondary air large nozzle serves as a boiler combustion auxiliary air.

[0015] Preferably, each corner of the tangentially-fired boiler body is provided with a fourth secondary air large nozzle above the sixth ammonia-hydrogen injection nozzle, and the fourth secondary air large nozzle serves as a main combustion zone overfire air.

[0016] Preferably, each corner of the tangentially-fired boiler body is provided with a first secondary air small nozzle between the second ammonia-hydrogen injection nozzle and the third ammonia-hydrogen injection nozzle, and a second secondary air small nozzle between the fourth ammonia-hydrogen injection nozzle and the fifth ammonia-hydrogen injection nozzle, and the first secondary air small nozzle and the second secondary air small nozzle are used to supplement the required oxygen for the main combustion region.

[0017] Preferably, each corner of the tangentially-fired boiler body is provided with a plurality of overfire air nozzles capable of vertical and horizontal swinging.

[0018] The working method of the low-nitrogen coal-fired boiler with ammonia and hydrogen doping as described above comprises the following steps:

[0019] During the combustion of the coal-fired boiler, 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 gas fuel outlet of the ammonia and hydrogen doping nozzle, and the hydrogen enters the main combustion area through the hydrogen gas fuel outlet cylinder of the ammonia and hydrogen doping nozzle.

[0020] During the combustion of the coal-fired boiler, in the main combustion area, all the fuel and most of the air are sent in to make the fuel burn under oxygen-deficient conditions to reduce the generation of nitrogen oxides; wherein the primary air nozzle divides the primary air into two parts with different concentrations, the dense phase is inside, the tangential circle of combustion is relatively small, and the flame center is closer; the dilute phase is outside, the tangential circle of combustion is relatively large; the flame temperature in the dense phase is relatively high, and the oxygen content is relatively low to reduce the generation of nitrogen oxides; the temperature outside the dilute phase is relatively low, and the oxygen is relatively more to reduce the generation of nitrogen oxides; at the same time, the ammonia and hydrogen doping nozzle sends in ammonia and hydrogen, the flame speed of ammonia is relatively slow, the flame temperature is relatively low, and the ammonia is arranged outside the primary air nozzle to delay the mixing of the pulverized coal and oxygen, thereby reducing the generation of nitrogen oxides; the addition of hydrogen can improve the combustion speed and temperature, and the rapid combustion of hydrogen can drive the combustion of ammonia and reduce the nitrogen oxides in the initial stage of coal combustion.

[0021] In the overfire air area, the remaining air is sent in through the overfire air nozzle, the flame temperature here is relatively low, and the nitrogen oxides generated in the main combustion area are reduced, further reducing the generation of nitrogen oxides.

[0022] The present application has the following advantages:

[0023] The application has the advantages that, compared with the existing burner arrangement structure, by controlling the supply of air and coal, ammonia and hydrogen fuels, the combustion process is carried out in stages, and the generation of nitrogen oxides is effectively reduced. First, in the main combustion area, all fuels and most of the air are sent in through the nozzle, the local oxygen concentration and temperature are reduced, the fuel is burned under the condition of oxygen deficiency, a reducing atmosphere is formed in the main combustion area, and the generation of nitrogen oxides is effectively reduced. Among them, the primary air nozzle and the stable combustion tooth divide the primary air into two thick and thin phases horizontally, the thick phase is inside, the combustion tangent circle is small, and it is closer to the flame center, the thin phase is outside, and the combustion tangent circle is large. The flame temperature in the thick phase is high, but the oxygen is less, so the generated nitrogen oxides are less, while the temperature outside the thin phase is low, and the oxygen is more, so the generated nitrogen oxides are less. At the same time, the ammonia and hydrogen are sent in through the ammonia and hydrogen nozzle, the flame speed of ammonia is slow, the flame temperature is low, and the ammonia is arranged outside the primary air nozzle, which can delay the mixing of coal powder and oxygen and reduce the generation of nitrogen oxides, and the addition of hydrogen can improve the combustion speed and temperature, the rapid combustion characteristics of hydrogen can drive the combustion of ammonia, and can reduce the nitrogen oxides in the initial stage of coal combustion. Secondly, after the main combustion process, the remaining air is sent in through the burnout air nozzle of the burnout area, the flame temperature here is low, and part of the nitrogen oxides generated in the main combustion area can be reduced, further reducing the generation of nitrogen oxides. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 The structure diagram of the coal-fired boiler with low nitrogen content of the present application.

[0026] Figure 2 The structure diagram of the ammonia and hydrogen mixing nozzle of the coal-fired boiler with low nitrogen content of the present application.

[0027] Figure 3 The structure diagram of the primary air nozzle of the coal-fired boiler with low nitrogen content of the present application.

[0028] In the figure: 101 - first secondary air large nozzle, 102 - second secondary air large nozzle, 103 - third secondary air large nozzle, 104 - fourth secondary air large nozzle, 201 - first ammonia-hydrogen mixing nozzle, 202 - second ammonia-hydrogen mixing nozzle, 203 - third ammonia-hydrogen mixing nozzle, 204 - fourth ammonia-hydrogen mixing nozzle, 205 - fifth ammonia-hydrogen mixing nozzle, 206 - sixth ammonia-hydrogen mixing 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 - pulverized coal fuel outlet, 3-2 - stable combustion tooth, 3-3 - gap air outlet, 401 - first secondary air small nozzle, 402 - second secondary air small nozzle, 5 - overfire air nozzle, 6 - four-corner tangential boiler body. DETAILED DESCRIPTION

[0029] According to the technical scheme of the present application, those skilled in the art can propose various alternative structures and implementation manners without changing the essential spirit of the present application. Therefore, the following detailed description and drawings are only exemplary illustrations of the technical scheme of the present application, and should not be regarded as the whole or limitation of the technical scheme of the present application.

[0030] Reference Figures 1-3 The ammonia-hydrogen mixing low-nitrogen coal-fired boiler of the embodiment includes a four-corner tangential boiler body 6, a plurality of primary air nozzles are arranged at each corner of the four-corner tangential boiler body 6 in the height direction in the main combustion area, a stable combustion tooth 3-2 is arranged on the primary air nozzle, the stable combustion tooth 3-2 is used for dividing the primary air into two thick and thin streams horizontally, and the thick phase is inside and the thin phase is outside; an ammonia-hydrogen mixing nozzle is arranged above and / or below each primary air nozzle; and an overfire air nozzle 5 is arranged at each corner of the four-corner tangential boiler body 6 in the overfire air area.

[0031] The working method of the ammonia-hydrogen mixing low-nitrogen coal-fired boiler described in the above embodiment of the present application includes the following processes:

[0032] 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, the ammonia enters the main combustion area through the ammonia fuel outlet 2-2 in the ammonia-hydrogen mixing nozzle, and the hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder 2-1 of the ammonia-hydrogen mixing nozzle;

[0033] In the main combustion area, all the fuel and most of the air are sent in to make the fuel burn under the condition of oxygen deficiency, so as to reduce the generation of nitrogen oxides; wherein, the primary air nozzle makes the primary air horizontally into two thick and thin phases, the thick phase is inside, the combustion tangential circle is relatively small, and is closer to the flame center, the thin phase is outside, the combustion tangential 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 thin phase is relatively low, and the oxygen is relatively more, so as to reduce the generation of nitrogen oxides; at the same time, the ammonia and hydrogen mixing nozzle sends in ammonia and hydrogen, the flame speed of ammonia is relatively slow, the flame temperature is relatively low, and the ammonia is arranged outside the primary air nozzle, so as to delay the mixing of the pulverized coal and oxygen, and further reduce the generation of nitrogen oxides; the addition of hydrogen can improve the combustion speed and temperature, the rapid combustion of hydrogen is utilized to drive the combustion of ammonia, and the nitrogen oxides in the initial stage of the coal combustion are reduced;

[0034] In the overfire air area, the remaining air is sent in through the overfire air nozzle 5, the flame temperature here is relatively low, the part of the nitrogen oxides generated in the main combustion area is reduced, and the generation of nitrogen oxides is further reduced.

[0035] As a preferred embodiment of the present application, see Figure 1 In the embodiment, five primary air nozzles are arranged, specifically 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, and 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.

[0036] As a preferred embodiment of the present application, on the basis of the above embodiment, in the embodiment, six ammonia and hydrogen mixing nozzles are arranged, specifically including a first ammonia and hydrogen mixing nozzle 201, a second ammonia and hydrogen mixing nozzle 202, a third ammonia and hydrogen mixing nozzle 203, a fourth ammonia and hydrogen mixing nozzle 204, a fifth ammonia and hydrogen mixing nozzle 205 and a sixth ammonia and hydrogen mixing nozzle 206;

[0037] See Figure 1The first ammonia-hydrogen mixing nozzle 201 is arranged below the first primary air nozzle 301, the second ammonia-hydrogen mixing nozzle 202 is arranged above the second primary air nozzle 302, the third ammonia-hydrogen mixing nozzle 203 is arranged below the third primary air nozzle 303 and above the second ammonia-hydrogen mixing nozzle 202, the fourth ammonia-hydrogen mixing nozzle 204 is arranged above the third primary air nozzle 303, the fifth ammonia-hydrogen mixing nozzle 205 is arranged below the fourth primary air nozzle 304 and above the fourth ammonia-hydrogen mixing nozzle 204, and the sixth ammonia-hydrogen mixing nozzle 206 is arranged above the fifth primary air nozzle 305. The ammonia-hydrogen mixing 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 mixing nozzle is arranged above and / or below the primary air nozzle, which can delay the mixing of coal powder and oxygen, reduce the generation of nitrogen oxides, and at the same time, hydrogen can be added through the hydrogen fuel outlet cylinder 2-1. The addition of hydrogen can improve the combustion speed and temperature, and the rapid combustion characteristics of hydrogen can drive the combustion of ammonia and reduce the nitrogen oxides in the initial stage of coal combustion.

[0038] As a preferred embodiment of the present application, on the basis of the above embodiment, in this embodiment, a first secondary air large nozzle 101 is arranged at the bottom of each corner of the four-corner tangential circle boiler body 6 below the first ammonia-hydrogen mixing nozzle 201, and the first secondary air large nozzle 101 serves as the bottom support wind. The use of a secondary air large nozzle for the bottom layer of support wind can increase the secondary air flow at this position and effectively reduce the generation of slag.

[0039] As a preferred embodiment of the present application, on the basis of the above embodiment, in this embodiment, a second secondary air large nozzle 102 is arranged between the first primary air nozzle 301 and the second primary air nozzle 302 at each corner of the four-corner tangential circle boiler body 6, and the second secondary air large nozzle 102 serves as the boiler combustion auxiliary wind. The use of a secondary air large nozzle for the boiler combustion auxiliary wind between the two primary air nozzles of the bottom layer and between the two primary air nozzles of the top layer can ensure the stability of the combustion in the main combustion area of the boiler.

[0040] As a preferred embodiment of the present application, on the basis of the above embodiment, in this embodiment, a third secondary air large nozzle 103 is arranged between the fourth primary air nozzle 304 and the fifth primary air nozzle 305 at each corner of the four-corner tangential circle boiler body 6, and the third secondary air large nozzle 103 serves as the boiler combustion auxiliary wind. The use of a secondary air large nozzle for the top layer of burnout wind in the main combustion area can increase the secondary air flow at this position and effectively reduce the generation of fly ash.

[0041] As a preferred embodiment of the present application, on the basis of the above-mentioned embodiment, in this embodiment, each corner of the tangentially cut boiler body 6 is provided with a fourth large secondary air nozzle 104 above the sixth ammonia-hydrogen injection nozzle 206, and the fourth large secondary air nozzle 104 is used as the main combustion zone overfire air.

[0042] As a preferred embodiment of the present application, on the basis of the above-mentioned embodiment, in this embodiment, each corner of the tangentially cut boiler body 6 is provided with a first small secondary air nozzle 401 between the second ammonia-hydrogen injection nozzle 202 and the third ammonia-hydrogen injection nozzle 203, and a second small secondary air nozzle 402 between the fourth ammonia-hydrogen injection nozzle 204 and the fifth ammonia-hydrogen injection nozzle 205, and the first small secondary air nozzle 401 and the second small secondary air nozzle 402 are used to supplement the required oxygen for the main combustion zone. In this embodiment, the small secondary air nozzles are located between two ammonia-hydrogen injection nozzles and also between two primary air nozzles, and the small secondary air nozzles are used to supplement the required oxygen for the main combustion zone.

[0043] As a preferred embodiment of the present application, on the basis of the above-mentioned embodiment, in this embodiment, each corner of the tangentially cut boiler body 6 is provided with a plurality of overfire air nozzles 5 in the overfire air zone, and the plurality of overfire air nozzles 5 can be vertically and horizontally oscillated according to the needs of combustion adjustment. The overfire air nozzles are used to send secondary air remaining air into the furnace of the tangentially cut boiler body 6, and since the flame temperature in the overfire air zone is relatively low, it can reduce part of the nitrogen oxides generated in the main combustion zone, further reducing the generation of nitrogen oxides.

[0044] Embodiment

[0045] Reference Figures 1-3 The ammonia-hydrogen injection low-nitrogen coal-fired boiler of the present application comprises a tangentially cut boiler body 6, and a plurality of large secondary air nozzles, ammonia-hydrogen injection nozzles, primary air nozzles, small secondary air nozzles, and overfire air nozzles 5 are arranged at each corner of the tangentially cut boiler body 6, and the specific structure is as follows:

[0046] In this embodiment, five primary air nozzles are provided, which are respectively denoted as first primary air nozzle 301, second primary air nozzle 302, third primary air nozzle 303, fourth primary air nozzle 304 and fifth primary air nozzle 305, and 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. Six ammonia-hydrogen mixing nozzles are provided, which are respectively denoted as first ammonia-hydrogen mixing nozzle 201, second ammonia-hydrogen mixing nozzle 202, third ammonia-hydrogen mixing nozzle 203, fourth ammonia-hydrogen mixing nozzle 204, fifth ammonia-hydrogen mixing nozzle 205 and sixth ammonia-hydrogen mixing nozzle 206; four large secondary air nozzles, which are respectively denoted as first large secondary air nozzle 101, second large secondary air nozzle 102, third large secondary air nozzle 103 and fourth large secondary air nozzle 104; two small secondary air nozzles, which are respectively denoted as first small secondary air nozzle 401 and second small secondary air nozzle 402; and four burnout air nozzles.

[0047] 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 tangential boiler body 6 as the bottom support air, the fourth large secondary air nozzle 104 is arranged at the top layer of the main combustion area of the boiler as the main combustion area burnout air, the second large secondary air nozzle 102 is arranged between the two primary air nozzles (i.e., the first primary air nozzle 301 and the second primary air nozzle 302) at the bottom layer as the boiler combustion auxiliary air, and the third large secondary air nozzle 103 is arranged between the two primary air nozzles (i.e., the fourth primary air nozzle 304 and the fifth primary air nozzle 305) at the top layer as the boiler combustion auxiliary air. The bottom support air at the bottom layer uses the large secondary air nozzle to increase the secondary air flow at this position and effectively reduce the generation of slag. The main combustion area burnout air at the top layer uses the large secondary air nozzle to increase the secondary air flow at this position and effectively reduce the generation of fly ash. 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 uses the large secondary air nozzle, and the large secondary air flow at this position can ensure the stability of the combustion of the main combustion area of the boiler.

[0048] The first ammonia-hydrogen mixing nozzle 201 is arranged between the first primary air nozzle 301 and the first secondary air large nozzle 101, the second ammonia-hydrogen mixing nozzle 202 is arranged above the second primary air nozzle 302, the third ammonia-hydrogen mixing nozzle 203 is arranged below the third ammonia-hydrogen mixing nozzle 203 and above the second ammonia-hydrogen mixing nozzle 202, the fourth ammonia-hydrogen mixing nozzle 204 is arranged above the third ammonia-hydrogen mixing nozzle 203, the fifth ammonia-hydrogen mixing nozzle 205 is arranged below the fourth primary air nozzle 304 and above the fourth ammonia-hydrogen mixing nozzle 204, and the sixth ammonia-hydrogen mixing nozzle 206 is arranged between the fifth primary air nozzle 305 and the fourth secondary air large nozzle 104; all the ammonia-hydrogen mixing nozzles are provided with a hydrogen fuel outlet cylinder 2-1, and the hydrogen fuel outlet cylinder 2-1 is provided with an ammonia fuel outlet 2-2 on both sides. The flame speed of ammonia is slow, the flame temperature is low, the ammonia-hydrogen mixing nozzle is arranged above and below the primary air nozzle, the mixing of the pulverized coal and oxygen can be delayed, the generation of nitrogen oxides can be reduced, the addition of hydrogen can improve the combustion speed and temperature, the rapid combustion characteristics of hydrogen can drive the combustion of ammonia, and the nitrogen oxides in the initial stage of coal combustion can be reduced.

[0049] The first secondary air small nozzle 401 is arranged between the second ammonia-hydrogen mixing nozzle 202 and the third ammonia-hydrogen mixing nozzle 203, and the second secondary air small nozzle 402 is arranged between the fourth ammonia-hydrogen mixing nozzle 204 and the fifth ammonia-hydrogen mixing nozzle 205. It can be seen that the two secondary air small nozzles are arranged between the two ammonia-hydrogen mixing nozzles 2 and between the two primary air nozzles 3. The secondary air small nozzle can supplement the required oxygen for the main combustion area.

[0050] It can be seen that in the embodiment, the four primary air nozzles are spaced apart by secondary air large nozzles, ammonia-hydrogen mixing nozzles or secondary air small nozzles, and all the primary air nozzles are provided with stable combustion teeth 3-2. The primary air nozzle and the stable combustion tooth divide the primary air into two thick and thin phases horizontally, the thick phase is inside, the combustion cut circle is small, and it is closer to the flame center, and the thin phase is outside, the combustion cut circle is large. The flame temperature in the thick phase is high, but the oxygen is less, so the generated nitrogen oxides are less, and the temperature outside the thin phase is low, the oxygen is more, and the generated nitrogen oxides are less.

[0051] The four burnout air nozzles 5 are arranged in the burnout area above the main combustion area respectively, and the burnout air nozzles 5 can be vertically and horizontally swung according to the needs of combustion adjustment. The burnout air nozzles send in the remaining air of the secondary air, the flame temperature here is low, and part of the nitrogen oxides generated in the main combustion area can be reduced, further reducing the generation of nitrogen oxides.

[0052] The working method of the ammonia-hydrogen mixing low-nitrogen coal-fired boiler in the embodiment includes the following processes:

[0053] During combustion in a coal-fired boiler, pulverized coal enters the main combustion zone through the pulverized coal fuel outlet 3-1 of the primary air nozzle, ammonia enters the main combustion zone through the ammonia fuel outlet 2-2 of the ammonia and hydrogen blending nozzle 2, and hydrogen enters the main combustion zone through the hydrogen fuel outlet cylinder 2-1. Secondary air enters the main combustion zone through the large secondary air nozzle and the small secondary air nozzle, interstitial air enters the main combustion zone through the interstitial air outlet 3-3 of the primary air nozzle, and overburned air enters the overburned air zone through the overburned air nozzle 5. The primary air flow rate entering the furnace is 20-25 m / s, the secondary air flow rate is 45-55 m / s, the ammonia flow rate is 60-80 m / s, and the hydrogen flow rate is 80-100 m / s. The overburned air and interstitial air have the same velocity as the secondary air.

[0054] During boiler combustion, all the fuel and most of the air are introduced into the main combustion zone, causing the fuel to burn in an oxygen-deficient environment, effectively reducing the formation of nitrogen oxides. The primary air nozzles separate the primary air horizontally into two streams: a dense phase, located inner and with a smaller combustion tangent circle closer to the flame center, and a lean phase, located outer and with a larger combustion tangent circle. The flame temperature within the dense phase is higher, but oxygen is lower, resulting in less nitrogen oxides. The lean phase, however, has a lower temperature, more oxygen, and therefore less nitrogen oxides. Furthermore, ammonia and hydrogen nozzles introduce ammonia and hydrogen. Ammonia has a slower flame speed and lower flame temperature. Positioned outside the primary air nozzles, these nozzles delay the mixing of pulverized coal and oxygen, reducing the formation of nitrogen oxides. The addition of hydrogen increases the combustion speed and temperature. The rapid combustion of hydrogen drives the combustion of ammonia and reduces nitrogen oxides in the early stages of pulverized coal combustion.

[0055] In the overburn air area, the remaining air is introduced through the overburn 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.

[0056] In this embodiment, the airflow ejected from the four-corner burners of the coal-fired boiler forms four-corner tangential combustion, and a rotating layer of combustion airflow is formed in both the vertical and horizontal directions.

[0057] As can be seen from the above, 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.

[0058] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention. They should all be regarded as belonging to the present invention, and the scope of patent protection shall be determined by the submitted claims.

[0059] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A coal-fired boiler with mixed ammonia and hydrogen and low nitrogen content, characterized in that: The invention comprises a four-corner tangential boiler body (6), wherein each corner of the four-corner tangential boiler body (6) is provided with a plurality of primary air nozzles at intervals 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 lean phase outside; an ammonia-hydrogen mixing nozzle is provided above and / or below each primary air nozzle; the primary air nozzle is provided with a pulverized coal fuel outlet (3-1), each ammonia-hydrogen mixing nozzle has a hydrogen fuel outlet cylinder (2-1), and both sides of each hydrogen fuel outlet cylinder (2-1) have ammonia fuel outlets (2-2); Each corner of the four-corner tangential boiler body (6) is provided with a burnt air nozzle (5) in the burnt air area.

2. The coal-fired boiler with ammonia and hydrogen mixed 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 and hydrogen mixed 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 mixing nozzle (201) is arranged below the first primary air nozzle (301), the second ammonia-hydrogen mixing nozzle (202) is arranged above the second primary air nozzle (302), the third ammonia-hydrogen mixing nozzle (203) is arranged below the third primary air nozzle (303) and above the second ammonia-hydrogen mixing nozzle (202), the fourth ammonia-hydrogen mixing nozzle (204) is arranged above the third primary air nozzle (303), the fifth ammonia-hydrogen mixing nozzle (205) is arranged below the fourth primary air nozzle (304) and above the fourth ammonia-hydrogen mixing nozzle (204), and the sixth ammonia-hydrogen mixing nozzle (206) is arranged above the fifth primary air nozzle (305).

4. The coal-fired boiler with ammonia and hydrogen mixed 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 and hydrogen mixed 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 auxiliary air for boiler combustion.

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 the fourth primary air nozzle (304) and the 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 auxiliary air for boiler combustion.

7. The coal-fired boiler with ammonia and hydrogen mixed 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 tangential boiler body (6). The fourth large secondary air nozzle (104) serves as burnout air for the main combustion zone.

8. The coal-fired boiler with ammonia and hydrogen mixed and low nitrogen content according to claim 3, characterized in that: At each corner of the four-corner tangential boiler body (6), a first small secondary air nozzle (401) is provided between the second ammonia and hydrogen nozzle (202) and the third ammonia and hydrogen nozzle (203), and a second small secondary air nozzle (402) is provided between the fourth ammonia and hydrogen nozzle (204) and the fifth ammonia and hydrogen 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 and hydrogen mixed 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 and hydrogen added and low nitrogen content according to any one of claims 1 to 9, characterized in that: include: When the coal-fired boiler is burning, 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 mixing nozzle, and hydrogen enters the main combustion area through the hydrogen fuel outlet cylinder (2-1) of the ammonia and hydrogen mixing nozzle; 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; the primary air nozzle divides the primary air horizontally into two streams, a dense phase inside, with a relatively small combustion circle closer to the flame center, and a light phase outside, with a relatively large combustion 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; the temperature outside the light 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. It is arranged on the outside of 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 the rapid combustion of hydrogen can be used to drive the combustion of ammonia and reduce nitrogen oxides in the early stage of coal powder combustion; In the overburn air area, the remaining air is introduced through the overburn air nozzle (5), where the flame temperature is relatively low, and part of the nitrogen oxides generated in the main combustion area are reduced, thereby further reducing the generation of nitrogen oxides.

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