A pulverized coal burner with a hydrogen-containing fuel combustion nozzle

Abstract

The application discloses a pulverized coal burner with a hydrogen-containing fuel combustion nozzle, which outputs pulverized coal-air mixture to a combustion area through a first air pipe assembly, outputs hydrogen-containing stable combustion fuel to the pulverized coal-air mixture through a first fuel pipe assembly, and is ignited by an igniter; and an inner second air pipe assembly, a second fuel pipe assembly and an outer second air pipe assembly are sequentially sleeved to form an inner annular mixed flow and an outer annular mixed flow which surround the pulverized coal-air mixture, respectively. The embodiment adds a hydrogen combustion nozzle of a micro-mixed diffusion combustion mode to a conventional coal combustion burner, and two fuel paths enter, one of which ignites and stabilizes combustion in the center of the burner, and the second fuel path is divided into two streams from the inner second air path and the outer second air path to participate in combustion, which is responsible for increasing the air temperature and reducing the ignition delay time of the pulverized coal, and the three sprayed combustion gases adopt the micro-mixed diffusion combustion mode, which avoids the situation that backfire and large-area high-temperature area cause a sharp increase in NOx.

Description

Technical Field

[0001] This invention belongs to the field of pulverized coal combustion technology, and particularly relates to a pulverized coal burner with a hydrogen-containing fuel combustion nozzle. Background Technology

[0002] Traditional pulverized coal combustion technology has revealed significant shortcomings in applications involving low-quality coal. While swirl burners enhance stable combustion through pulverized coal enrichment and high-temperature flue gas recirculation, they are poorly adapted to low-reactivity coals (such as anthracite). High ignition temperatures and long burnout cycles easily lead to combustion lag and flame center shift, resulting in increased unburned carbon loss, high fly ash carbon content, and increased NOx generation in localized high-temperature zones. Furthermore, the difficulty in pulverized coal ignition due to furnace temperature decay under low-load conditions forces the system to rely on fuel oil, increasing operating costs and generating additional carbon emissions. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a pulverized coal burner with a hydrogen fuel combustion nozzle, so as to solve the problems of combustion stability and low load limit of stable combustion in pulverized coal combustion technology.

[0004] To solve the above problems, the technical solution of the present invention is as follows: The present invention provides a pulverized coal burner with a hydrogen-containing fuel combustion nozzle, comprising: The first air pipe assembly is configured to output a pulverized coal-air mixture to the combustion zone; A first fuel pipe assembly is configured to pass through the first air pipe assembly and output hydrogen-containing stable fuel to be mixed into the pulverized coal-air mixture; An igniter is arranged in the first fuel pipe assembly and the ignition end of the igniter corresponds to the pulverized coal combustion area, used to ignite the hydrogen-containing stable fuel. A second air pipe assembly, a second fuel pipe assembly, and an outer second air pipe assembly are sequentially fitted radially outward from the first air pipe assembly. The second fuel pipe assembly is configured to have an inner hydrogen-containing fuel flow and an outer hydrogen-containing fuel flow radially inward and outward. The inner hydrogen-containing fuel flow is configured to mix with the air output from the inner second air pipe assembly and output an inner annular mixed flow surrounding the pulverized coal-air mixture to the combustion zone. The outer hydrogen-containing fuel flow is configured to mix with the air output from the outer second air pipe assembly and output an outer annular mixed flow surrounding the inner annular mixed flow to the combustion zone. The inner annular mixing flow and the outer annular mixing flow are used to burn and increase the air temperature in the combustion zone to reduce the ignition delay time of the pulverized coal.

[0005] The present invention relates to a pulverized coal burner with a hydrogen fuel combustion nozzle, wherein the first air pipe assembly includes a first air pipe inlet section and a first air pipe outlet section connected together, wherein the first air pipe inlet section is a bend, and the first air pipe outlet section is provided with a contraction-expansion section whose diameter gradually decreases and then expands along the flow direction.

[0006] The pulverized coal burner of the present invention has a plurality of outer turbulence serrations that are spaced apart in the circumferential direction and extend radially inward at the outlet of the first air pipe outlet section.

[0007] The present invention provides a pulverized coal burner with a hydrogen-containing fuel combustion nozzle, wherein the first fuel pipe assembly comprises a first fuel pipe inlet section, a first fuel pipe main body section, and a first fuel nozzle connected in sequence; at least a portion of the first fuel pipe main body section and the first fuel nozzle are inserted into the first air pipe assembly. The first fuel nozzle has an annular first fuel air baffle on its circumferential outer wall. The first fuel air baffle has a plurality of first fuel air openings spaced apart circumferentially. The first fuel nozzle has a first fuel injection hole corresponding to each of the first fuel air channels and located downstream.

[0008] The pulverized coal burner of the present invention has a hydrogen-containing fuel combustion nozzle, wherein the first fuel pipe assembly further includes a first fuel pipe sleeve and a separation baffle assembly connected in sequence. The first fuel pipe sleeve is fitted over at least a portion of the first fuel pipe body section; the separation baffle assembly includes conical plates spaced apart and with gradually increasing diameters, and cylindrical plates connected between adjacent conical plates, wherein the conical plates have openings evenly distributed along the axial direction, and the radial height of the most downstream conical plate exceeds the radial height of the first fuel air baffle.

[0009] The pulverized coal burner of the present invention has a first fuel air baffle with a plurality of inner turbulence serrations spaced circumferentially and extending radially outward.

[0010] The pulverized coal burner of the present invention has a hydrogen fuel combustion nozzle, wherein the inner second air pipe assembly includes an inner second air pipe inlet section and an inner second air vortex that are sleeved on and connected to the first air pipe assembly, and the inner second air vortex is an axial vortex.

[0011] The pulverized coal burner of the present invention has a hydrogen-containing fuel combustion nozzle, wherein the second fuel pipe assembly includes a second fuel body section sleeved on the inner side of the second air pipe assembly, and a second fuel inlet section radially connected to the second fuel body section; The outer wall surface of the downstream end face of the second fuel main body section is circumferentially distributed with a plurality of second fuel external injection holes, the inner wall surface of the downstream end face of the second fuel main body section is circumferentially distributed with a plurality of second fuel internal injection holes, and an internal injection hole baffle ring is provided on the inner wall surface of the downstream end face of the second fuel main body section, the diameter of the internal injection hole baffle ring gradually decreasing along the flow direction.

[0012] The pulverized coal burner of the present invention has a hydrogen fuel combustion nozzle, wherein the inner nozzle baffle ring is provided with a second fuel air gate corresponding to the second fuel inner nozzle. The second fuel air opening is fitted to the inner wall of the downstream end face of the second fuel body section, or a radial gap is formed between the second fuel air opening and the inner wall of the downstream end face of the second fuel body section.

[0013] The present invention provides a pulverized coal burner with a hydrogen-containing fuel combustion nozzle, wherein the outer second air pipe assembly includes an outer second air pipe inlet section and a second air cyclone separator sleeved on and connected to the second fuel pipe assembly, wherein an air intake vane is provided in the outer second air pipe inlet section.

[0014] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art: One embodiment of the present invention comprises a first air pipe assembly, a first fuel pipe assembly, and an igniter. The first air pipe assembly outputs a pulverized coal-air mixture to the combustion zone, while the first fuel pipe assembly outputs hydrogen-containing stable-burning fuel to the pulverized coal-air mixture. The igniter then ignites the fuel for micro-mixing diffusion combustion. Furthermore, by sequentially nesting a second air pipe assembly (inner and outer sides) around the first air pipe assembly radially outward, an inner annular mixing flow and an outer annular mixing flow are formed around the pulverized coal-air mixture, both also for micro-mixing diffusion combustion of the hydrogen-containing fuel. In other words, this embodiment adds a hydrogen nozzle with micro-mixing diffusion combustion to a conventional coal burner. Fuel enters in two streams; one stream ignites and stabilizes combustion at the center of the burner, while the second stream participates in combustion from both the inner and outer second air pipes, increasing air temperature and reducing the ignition delay time of the pulverized coal. The three streams of fuel ejected employ micro-mixing diffusion combustion, avoiding backfire and large-area high-temperature zones that could cause a surge in NOx.

[0015] One embodiment of the present invention combines a micro-mixing diffusion hydrogen combustion nozzle arranged uniformly at multiple points in the circumferential direction with a swirl pulverized coal burner to form a composite combustion field, thereby improving combustion dynamics characteristics.

[0016] By directionally injecting hydrogen into three different radial regions—the inner and outer second air pipe assemblies and the central position—through hydrogen nozzles (first fuel pipe assembly and second fuel pipe assembly), the flame shape generated by hydrogen becomes more compact. Adding a hydrogen flame to the pulverized coal flame improves combustion stability and low-load stable combustion performance for difficult-to-burn coal types. Simultaneously, the hydrogen micro-mixing diffusion nozzle avoids backfire problems. The rapid combustion characteristics of hydrogen suppress pulverized coal combustion pressure fluctuations, reducing the amplitude of combustion chamber pressure oscillations, and significantly decreasing the CO2 concentration in the flue gas after hydrogen-blended combustion. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention; Figure 2 This is a schematic diagram of the first fuel pipe assembly of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention; Figure 3 This is a schematic diagram of the second fuel pipe assembly of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention; Figure 4 This is a schematic diagram of the second fuel air opening of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention; Figure 5 This is another schematic diagram of the second fuel air passage of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle of the present invention; Figure 6 This is a cross-sectional view of the inner nozzle baffle ring of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle of the present invention; Figure 7 This is an axial schematic diagram of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention; Figure 8 This is a schematic diagram of the air flow path and fuel flow path of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention. Figure 9 This is a schematic diagram of the flame pattern at the first fuel pipe assembly of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle of the present invention. Figure 10 This is a schematic diagram of the flame pattern at the second fuel pipe assembly of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle of the present invention. Figure 11 This is a schematic diagram of another flame configuration at the second fuel pipe assembly of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention. Figure 12 This is a schematic diagram of the flame pattern of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention. Explanation of reference numerals in the attached drawings: 1. Igniter; 2. First fuel pipe assembly; 21. First fuel pipe inlet section; 22. First fuel pipe sleeve; 23. Separation baffle assembly; 231. Conical plate; 232. Cylindrical plate; 233. Opening; 3. First air pipe assembly; 31. First air pipe inlet section; 32. Second air pipe outlet section; 321. Outer turbulence serrations; 4. Inner second air pipe assembly; 41. Inner second air pipe inlet section; 42. Inner second air cyclone separator; 5. Second Fuel pipe assembly; 51, second fuel pipe inlet section; 52, inner nozzle retaining ring; 521, second fuel air gate; 53, second inner fuel nozzle; 54, second outer fuel nozzle; 55, replaceable retaining ring; 6, outer second air pipe assembly; 61, outer second air pipe inlet section; 62, air intake vane; 63, second air vortex; 7, first fuel nozzle; 71, first fuel nozzle; 8, first fuel air baffle; 81, first fuel air gate; 82, inner turbulence serrations. Detailed Implementation

[0018] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a pulverized coal burner with a hydrogen-containing fuel combustion nozzle according to the present invention. The advantages and features of the invention will become clearer from the following description and claims.

[0019] See Figures 1 to 12 In one embodiment, a pulverized coal burner with a hydrogen-containing fuel combustion nozzle includes a first air pipe assembly 3, a first fuel pipe assembly 2, an igniter 1, an inner second air pipe assembly 4, a second fuel pipe assembly 5, and an outer second air pipe assembly 6.

[0020] The first air pipe assembly 3 is configured to output a pulverized coal-air mixture to the combustion zone. The first fuel pipe assembly 2 is configured to pass through the first air pipe assembly 3 and output hydrogen-containing stable-burning fuel to mix with the pulverized coal-air mixture. The igniter 1 is arranged in the first fuel pipe assembly 2 with its ignition end corresponding to the pulverized coal combustion zone, and is used to ignite the hydrogen-containing stable-burning fuel.

[0021] The inner second air pipe assembly 4, the second fuel pipe assembly 5, and the outer second air pipe assembly 6 are sequentially fitted radially outward onto the first air pipe assembly 3. The second fuel pipe assembly 5 is configured to have an inner hydrogen-containing fuel flow and an outer hydrogen-containing fuel flow radially inward and outward. The inner hydrogen-containing fuel flow is configured to mix with the air output from the inner second air pipe assembly 4 and output an inner annular mixed flow surrounding the pulverized coal-air mixture to the combustion zone; the outer hydrogen-containing fuel flow is configured to mix with the air output from the outer second air pipe assembly 6 and output an outer annular mixed flow surrounding the inner annular mixed flow to the combustion zone.

[0022] The inner and outer annular mixing flows are used for combustion and to increase the air temperature in the combustion zone to reduce the ignition delay time of the pulverized coal.

[0023] In this embodiment, a first air pipe assembly 3, a first fuel pipe assembly 2, and an igniter 1 are provided. The first air pipe assembly 3 outputs a pulverized coal-air mixture to the combustion zone, and the first fuel pipe assembly 2 outputs hydrogen-containing stable-burning fuel to the pulverized coal-air mixture. The igniter 1 then ignites the mixture to achieve micro-mixing diffusion combustion of the hydrogen-containing stable-burning fuel. Furthermore, by providing a second air pipe assembly 4, a second fuel pipe assembly 5, and a second air pipe assembly 6 arranged radially outwards on the inner side of the first air pipe assembly 3, an inner annular mixing flow and an outer annular mixing flow surrounding the pulverized coal-air mixture are formed, both of which are micro-mixing diffusion combustion of the hydrogen-containing fuel. In this embodiment, a hydrogen nozzle with micro-mixing diffusion combustion is added to a traditional coal-fired burner. The fuel enters in two streams. One stream is ignited and stabilized at the center of the burner, while the second stream participates in combustion from the inner second air path and the outer second air path. This stream is responsible for increasing the air temperature and reducing the ignition delay time of the pulverized coal. The three streams of fuel gas are injected using micro-mixing diffusion combustion, which avoids backfire and large-area high-temperature zones that could cause a surge in NOx.

[0024] This embodiment combines a micro-mixing diffusion hydrogen nozzle with a circumferentially uniformly arranged multi-point hydrogen combustion nozzle with a swirl pulverized coal burner to form a composite combustion field, thereby improving combustion dynamics characteristics.

[0025] By directionally injecting hydrogen into three different radial regions—inner, outer, and central—through hydrogen nozzles (first fuel pipe assembly 2 and second fuel pipe assembly 5), the flame shape generated by hydrogen becomes more compact. Adding a hydrogen flame to the pulverized coal flame improves combustion stability and low-load stable combustion performance for difficult-to-burn coal types. Simultaneously, the hydrogen micro-mixing diffusion nozzle avoids backfire problems. The rapid combustion characteristics of hydrogen suppress pulverized coal combustion pressure fluctuations, reducing the amplitude of combustion chamber pressure oscillations, and significantly decreasing the CO2 concentration in the flue gas after hydrogen-blended combustion.

[0026] The specific structure of the pulverized coal burner with a hydrogen fuel combustion nozzle in this embodiment will be further described below: In this embodiment, the first air pipe assembly 3 includes a first air pipe inlet section 31 and a first air pipe outlet section connected together. The first air pipe inlet section 31 is a bend, and the first air pipe outlet section is provided with a contraction-expansion section whose diameter gradually decreases and then expands along the flow direction. The contraction-expansion section is located in the middle section of the first air pipe outlet section to improve the mixing degree of coal powder in air.

[0027] Furthermore, the outlet of the first air pipe outlet section is provided with a plurality of outer turbulence serrations 321 that are spaced apart in the circumferential direction and extend radially inward. The number, cross-sectional shape and size of the outer turbulence serrations 321 can be arbitrary.

[0028] In this embodiment, the first fuel pipe assembly 2 includes a first fuel pipe inlet section 21, a first fuel pipe main body section, and a first fuel nozzle 7 connected in sequence. At least a portion of the first fuel pipe main body section and the first fuel nozzle 7 are inserted into the first air pipe assembly 3. Specifically, the first fuel pipe inlet section 21 may be radially disposed at the tail end of the first fuel pipe main body section. The chamber shape of the first fuel pipe main body section and the first fuel nozzle 7 is annular. The first fuel nozzle 7 is made of a high-temperature resistant metal material, which is a different material from that used for the first fuel inlet section.

[0029] The first fuel nozzle 7 has an annular first fuel air baffle 8 on its circumferential outer wall (periphery). The first fuel air baffle 8 contacts the step downstream of the first fuel inlet section in the axial direction. The first fuel air baffle 8 has several first fuel air openings 81 spaced apart in the circumferential direction (specifically opened at the bottom of the first fuel air baffle 8 in the radial direction). The first fuel nozzle 7 has a first fuel injection hole 71 corresponding to each first fuel air channel and located downstream.

[0030] The number of first fuel air openings 81 is the same as the number of first fuel nozzles 71, and the axial position of each first fuel nozzle 71 corresponds to the centerline of its corresponding first fuel air opening 81. The first fuel air baffle 8 is provided with a plurality of inner turbulence serrations 82 spaced circumferentially and extending radially outward; that is, the radially inner side of the first fuel air baffle 8 consists of evenly distributed first fuel air openings 81, while the radially outer side consists of circumferentially evenly distributed inner turbulence serrations 82. The number and size of the inner turbulence serrations 82 can be arbitrary, and their cross-sectional shape is not limited to rectangles.

[0031] Furthermore, the first fuel pipe assembly 2 also includes a first fuel pipe sleeve 22 and a separation baffle assembly 23 connected in sequence. The first fuel pipe sleeve 22 is fitted over at least a portion of the first fuel pipe body section. The axial length of the first fuel pipe sleeve 22 is less than that of the first fuel inlet section. The first fuel pipe sleeve 22 has a wear-resistant and impact-resistant material and sufficient thickness to protect the first fuel inlet section from damage caused by the airflow carrying pulverized coal. The downstream end of the first fuel pipe sleeve 22 is connected to the separation baffle assembly 23. The separation baffle assembly 23 includes conical plates 231 arranged at intervals with gradually increasing diameters and cylindrical plates 232 connected between adjacent conical plates 231. The conical plates 231 have openings 233 evenly distributed along the axial direction, and the radial height of the downstream conical plate 231 exceeds the radial height of the first fuel air baffle 8. Figure 2 As shown.

[0032] In this embodiment, the inner second air pipe assembly 4 includes an inner second air pipe inlet section 41 and an inner second air cyclone separator 6342, which are sleeved on and connected to the first air pipe assembly 3. The inner second air pipe inlet section 41 has an annular chamber shape, its radial position is located on the outer wall of the first air outlet section, and its axial upstream position is connected to the flange of the first air outlet section. The inner second air cyclone separator 6342 is an axial cyclone separator, such as... Figure 3 As shown.

[0033] In this embodiment, the second fuel pipe assembly 5 includes a second fuel body section sleeved on the inner side of the second air pipe assembly 4, and a second fuel inlet section radially connected to the second fuel body section.

[0034] The chamber of the second fuel main section is annular in shape. Several external fuel injection holes 54 are circumferentially distributed on the outer wall of the downstream end face of the second fuel main section, with the axis of each external fuel injection hole 54 forming an angle α with the radial direction. Several internal fuel injection holes 53 are circumferentially distributed on the inner wall of the downstream end face of the second fuel main section, with the axis of each internal fuel injection hole 53 forming an angle β with the radial direction. A replaceable retaining ring 55 made of high-temperature resistant material is installed on the downstream annular end face of the second fuel main section. If the replaceable retaining ring 55 is damaged, a new replacement part can be installed on the front end face of the second fuel main section, such as... Figure 1 , Figure 3 As shown.

[0035] Furthermore, an inner nozzle baffle ring 52 (specifically, a rotating part with an approximately triangular cross-sectional area) is provided on the inner wall surface of the downstream end face of the second fuel body section. The diameter of the inner nozzle baffle ring 52 gradually decreases along the flow direction, meaning that the inner nozzle baffle ring 52 has an inclined surface or an approximately curved surface. The nozzle baffle ring can reduce the cross-sectional area of ​​the outlet channel of the second air cyclone separator 63, thereby increasing the cyclone intensity, such as... Figure 3 , Figure 4 As shown.

[0036] Furthermore, the inner nozzle retaining ring 52 is provided with second fuel air gates 521 that correspond one-to-one with the circumferential positions of the second fuel inner nozzles 53. The second fuel air gates 521 can have any size, and the cross-sectional shape is not limited to rectangle. The number of them is arbitrary, but the same as the number of second fuel inner nozzles 53. The axial position of the second fuel inner nozzle 53 corresponds to the centerline of its corresponding second fuel air gate 521.

[0037] The second fuel air opening 521 is fitted to the inner wall of the downstream end face of the second fuel main body section, or a radial gap is formed between the second fuel air opening 521 and the inner wall of the downstream end face of the second fuel main body section. That is, the second fuel air opening 521 can be opened at different radial positions on the inner nozzle baffle ring 52. The farther the second fuel air opening 521 is from the radial position of the second fuel inner nozzle 53, the later the fuel in the second fuel inner nozzle 53 is affected by air momentum, thus the greater the jet depth of the fuel ejected from the second fuel inner nozzle 53. Different radial positions of the second fuel air opening 521 on the inner nozzle baffle ring 52 can adjust the fuel jet depth of the second fuel inner nozzle 53, thereby changing the flame length. Figure 4 , 5 As shown, the flame shape is as follows Figure 10 , Figure 11 As shown.

[0038] In this embodiment, the outer second air pipe assembly 6 includes an outer second air pipe inlet section 61 and a second air cyclone separator 63, which are sleeved on and connected to the second fuel pipe assembly 5. The outer second air pipe inlet section 61 is provided with an intake vane 62. Specifically, the second air inlet section is located upstream and is for lateral air intake. The intake vane 62 is circumferentially distributed at the annular cavity inlet of the outer second air pipe inlet section 61, and its blade axis is the same as the axial direction of the burner. The second air cyclone separator 63 is located axially downstream of the outer second air pipe inlet section 61. At the outlet of the second air cyclone separator 63, more than one second external fuel injection hole 54 is arranged between the blades of each second air cyclone separator 63.

[0039] The operation process of the pulverized coal burner with a hydrogen-containing fuel combustion nozzle in this embodiment is described below: When the burner is running, air enters the burner via three paths: A, B, and C. Fuel enters the burner via two paths: a and b.

[0040] The first air path A is the transport air carrying pulverized coal fuel. It flows through the channel formed by the first air pipe inlet section 31, the first air outlet section, and the first fuel pipe sleeve 22. Before exiting the burner, it passes through the separation baffle assembly 23. The pulverized coal collides with the conical plates 231, and under inertia, forms two airflows on the annular cross-section of the channel: an outer ring with a high pulverized coal concentration (A1) and an inner ring with a low pulverized coal concentration (A2). Every two conical plates 231 are connected by a cylindrical plate 232. The diagram shows two conical plates 231, but the actual number can be adjusted to three or four depending on the burner length. Figure 2 , Figure 8 As shown.

[0041] After the high-concentration pulverized coal airflow A1 passes through the circumferentially distributed outer turbulence sawtooth 321 at the downstream end of the first air outlet section, the increased air turbulence due to the outer turbulence sawtooth 321 enhances the mixing degree of pulverized coal and air, which is beneficial for shortening the combustion time. For example... Figure 7 , Figure 8 As shown.

[0042] The inner ring low-coal-powder concentration airflow A2 passes through the circumferentially distributed openings 233 of the conical plate 231 and reaches the first fuel air baffle 8 along the axial direction. A portion of the inner ring low-coal-powder concentration airflow A21 near the bottom passes through the first fuel air portal 81 on the first fuel air baffle 8, flowing axially and forming a cross-jet with the hydrogen airflow a1 ejected radially from the first fuel nozzle 71. During the burner pneumatic stage, the fuel ignited by the igniter 1 at the first fuel nozzle 71 forms a central hydrogen flame. (The text abruptly ends here.) Figure 9 As shown.

[0043] The outer corner recirculation zone formed by the first fuel air baffle 8 and the area before the airflow A21, and the inner corner recirculation zone formed by the annular wall at the front end of the first fuel nozzle 71 and the airflow A21, mean that the fuel in the first fuel nozzle 71 exists within the shear layer of the two recirculation zones. After ignition, the hydrogen flame is fixed at the front end of the burner under the action of the two recirculation zones, and the flame area is as follows: Figure 9 As shown in the shaded area, the hydrogen flame is distributed circumferentially along the downstream end face of the first fuel nozzle 7.

[0044] This hydrogen flame can ignite pulverized coal. During operation, the flow rate a1 of the gas injected from the first fuel nozzle 71 can be adjusted according to the operating conditions. When the unit is burning difficult-to-burn, low-volatile coal, or when stable combustion is required at low loads, this hydrogen flame is used to ensure stable combustion.

[0045] The airflow A21 has uniformly distributed openings 233, i.e., first fuel injection holes 71, on the downstream outer wall of the first fuel nozzle 7. The first fuel air baffle 8 has a first fuel air gate 81 at the bottom in the radial direction. The first fuel air gate 81 can have any number and size, and the cross-sectional shape is not limited to rectangle.

[0046] The radial position of the second fuel air gate 521 within the inner nozzle baffle ring 52 can adjust the fuel jet depth of the second fuel inner nozzle 53, thereby changing the flame length. Figure 4 , 5 As shown, the flame shape is as follows Figure 10 , 11As shown. When the second fuel air gate 521 is located in a radial position further away from the wall, the flame length increases and the flame is more biased towards one side of the burner axis. Different radial positions of the second fuel air gate 521 in the inner nozzle baffle ring 52 can be used as an adjustment means. The flame position is different depending on the operating conditions of different boiler units and coal types. Adjusting the radial position of the second fuel air gate 521 in the inner nozzle baffle ring 52 can obtain a suitable flame length and height for fuel b1.

[0047] The second air stream B enters through the inlet of the inner second air pipe assembly 4. This air stream B does not contain pulverized coal fuel. The inlet section 41 of the inner second air pipe enters the annular chamber, flows axially, and is then ejected from the inner second air vortex generator 6342. At the burner outlet, the second air stream B is split into two streams at the inner nozzle baffle ring 52. One stream, B1, flows out after passing the inclined surface of the inner nozzle baffle ring 52. This airflow B1, in a swirling state, passes through the inclined surface of the inner nozzle baffle ring 52, effectively passing through a channel with a narrowing diameter, increasing the angle of expansion after exiting the burner and enhancing the swirling effect. The other air stream B1 is ejected axially through the second fuel air gate 521, intermingling with the fuel stream B1 ejected from the second fuel inner nozzle 53. The B2 airflow, along with the inner nozzle baffle ring 52 and the replaceable baffle ring 55, forms an outer and inner corner recirculation zone. The hydrogen flame generated by the fuel stream B1 is stabilized on the inner radius side of the front end of the replaceable baffle ring 55.

[0048] The third air stream C flows axially downstream after passing through the second air inlet section. The air stream C does not contain pulverized coal fuel. After passing through the second air cyclone separator 63, the third air stream C generates a swirling flow. The air stream C and the fuel stream b2 form a stable hydrogen flame, and the flame position is located on the outer radius side of the front end of the replaceable baffle ring 55.

[0049] Viewed from the axial direction of the burner, the hydrogen flames generated by fuel in the b1 and b2 paths are circumferentially distributed on both the inner and outer sides of the front end of the replaceable baffle ring 55, forming an annular high-temperature region.

[0050] Fuel streams a1, b1, and b2 are ejected from the first fuel injection hole 71, the second inner fuel injection hole 53, and the second outer fuel injection hole 54, respectively. The injection direction is not limited to the radial direction of the wall surface and the injection angle can be adjusted as needed.

[0051] The fuel ratios of a1, b1, and b2 are adjusted according to actual conditions and the air ratios of A, B, and C. The flame generated by fuel a1 is mainly used for ignition and stable combustion under low load, while the flames generated by fuels b1 and b2 are used to improve the combustion stability of difficult-to-burn coals. The radial position of the flames generated by fuels b1 and b2 at the burner outlet cross-section is between the radial positions of the second air supply B and the third air supply C. Since air supplies B and C, unlike air supply A, do not carry pulverized coal, the flames generated by fuels b1 and b2 between air supplies B and C, although circumferentially distributed on the inner and outer sides of the front end of the replaceable baffle ring 55, do not cause premature ignition of pulverized coal. The area overlapping with the pulverized coal flame area is small, mainly serving as heating air to shorten the pulverized coal ignition process, thus reducing the ignition delay time of difficult-to-burn coals. The flame generated by fuel a1 is located at the root of the pulverized coal flame, mainly serving for ignition and stable combustion under low load. Under high load or high volatile matter and low moisture coal types, this fuel supply can be reduced or even shut off.

[0052] The fuel types for the three fuels (a1, b1, and c1) are not limited to hydrogen; they can also include hydrogen-containing alkanes and hydrogen-oxygen mixtures or oxygen as combustion-supporting gases.

[0053] This embodiment integrates a hydrogen-fueling nozzle using micro-mixing diffusion combustion technology into a swirl-flow pulverized coal burner. Hydrogen, as a zero-carbon fuel, complements the physicochemical properties of pulverized coal. Hydrogen possesses high activity, a high diffusion coefficient, and a wide combustible range. By injecting hydrogen into the pulverized coal combustion field through micro-mixing diffusion combustion, the technical challenges of pollutant control and carbon emission reduction can be simultaneously addressed. The hydrogen-fueling nozzle injects highly active hydrogen or oxygen, utilizing the low ignition energy (0.02 mJ) and fast flame propagation speed (3 m / s) of hydrogen to create a localized high-temperature zone around the pulverized coal flow, reducing the ignition temperature of the pulverized coal. Simultaneously, the hydroxyl radicals (OH*) released during hydrogen combustion catalyze the oxidation reaction on the surface of the coal char, shortening the burnout time, improving the combustion efficiency of low-quality coal, and reducing the carbon content of fly ash.

[0054] Furthermore, the integration of the micro-mixing diffusion hydrogen fuel nozzle into the swirl pulverized coal burner improves the problem of difficult pulverized coal ignition caused by the drop in furnace temperature when the boiler load is below 40%-50%. The previous reliance on diesel or natural gas for combustion assistance, which increased operating costs and introduced additional carbon emissions, is also resolved. The hydrogen fuel nozzle maintains the burner outlet temperature by regulating the hydrogen flow rate, preventing flame rise. Simultaneously, it reduces CO2 emissions related to auxiliary fuels.

[0055] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A pulverized coal burner with a hydrogen-containing fuel combustion nozzle, characterized in that, include: The first air pipe assembly is configured to output a pulverized coal-air mixture to the combustion zone; A first fuel pipe assembly is configured to pass through the first air pipe assembly and output hydrogen-containing stable fuel to be mixed into the pulverized coal-air mixture; An igniter is arranged in the first fuel pipe assembly and the ignition end of the igniter corresponds to the pulverized coal combustion area, used to ignite the hydrogen-containing stable fuel. A second air pipe assembly, a second fuel pipe assembly, and an outer second air pipe assembly are sequentially fitted radially outward from the first air pipe assembly. The second fuel pipe assembly is configured to have an inner hydrogen-containing fuel flow and an outer hydrogen-containing fuel flow radially inward and outward. The inner hydrogen-containing fuel flow is configured to mix with the air output from the inner second air pipe assembly and output an inner annular mixed flow surrounding the pulverized coal-air mixture to the combustion zone. The outer hydrogen-containing fuel flow is configured to mix with the air output from the outer second air pipe assembly and output an outer annular mixed flow surrounding the inner annular mixed flow to the combustion zone. The inner annular mixing flow and the outer annular mixing flow are used to burn and increase the air temperature in the combustion zone to reduce the ignition delay time of the pulverized coal. The second fuel pipe assembly includes a second fuel body section sleeved on the inner side of the second air pipe assembly, and a second fuel inlet section radially connected to the second fuel body section; The outer wall surface of the downstream end face of the second fuel main body section is circumferentially distributed with a plurality of second fuel external injection holes, the inner wall surface of the downstream end face of the second fuel main body section is circumferentially distributed with a plurality of second fuel internal injection holes, and an internal injection hole baffle ring is provided on the inner wall surface of the downstream end face of the second fuel main body section, the diameter of the internal injection hole baffle ring gradually decreasing along the flow direction.

2. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 1, characterized in that, The first air pipe assembly includes a first air pipe inlet section and a first air pipe outlet section connected together, wherein the first air pipe inlet section is a bend, and the first air pipe outlet section is provided with a contraction-expansion section whose diameter gradually decreases and then expands along the flow direction.

3. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 2, characterized in that, The outlet of the first air pipe outlet section is provided with a number of outer turbulence serrations that are spaced apart in the circumferential direction and extend radially inward.

4. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 1, characterized in that, The first fuel pipe assembly includes a first fuel pipe inlet section, a first fuel pipe body section, and a first fuel nozzle connected in sequence; at least a portion of the first fuel pipe body section and the first fuel nozzle are inserted into the first air pipe assembly; The first fuel nozzle has an annular first fuel air baffle on its circumferential outer wall. The first fuel air baffle has a plurality of first fuel air openings spaced apart circumferentially. The first fuel nozzle has a first fuel injection hole corresponding to each of the first fuel air openings and located downstream.

5. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 4, characterized in that, The first fuel pipe assembly further includes a first fuel pipe sleeve and a separation baffle assembly connected in sequence; The first fuel pipe sleeve is fitted over at least a portion of the first fuel pipe body section; the separation baffle assembly includes conical plates spaced apart and with gradually increasing diameters, and cylindrical plates connected between adjacent conical plates, wherein the conical plates have openings evenly distributed along the axial direction, and the radial height of the most downstream conical plate exceeds the radial height of the first fuel air baffle.

6. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 4, characterized in that, The first fuel air baffle is provided with a plurality of inner turbulence serrations that are spaced apart in the circumferential direction and extend radially outward.

7. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 1, characterized in that, The inner second air pipe assembly includes an inner second air pipe inlet section and an inner second air vortex that are sleeved on and connected to the first air pipe assembly. The inner second air vortex is an axial vortex.

8. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 1, characterized in that, The inner nozzle baffle ring is provided with a second fuel air gate corresponding to the second fuel inner nozzle; The second fuel air opening is fitted to the inner wall of the downstream end face of the second fuel body section, or a radial gap is formed between the second fuel air opening and the inner wall of the downstream end face of the second fuel body section.

9. The pulverized coal burner with a hydrogen-containing fuel combustion nozzle as described in claim 1, characterized in that, The outer second air pipe assembly includes an outer second air pipe inlet section and a second air cyclone separator sleeved on and connected to the second fuel pipe assembly, wherein an air intake vane is provided in the outer second air pipe inlet section.

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