A swirl burner for ammonia-coal mixed combustion and its use method

Abstract

The present invention discloses a swirl burner for ammonia-coal mixed combustion, comprising first to third cylinders; the inner cavity of the first cylinder forms a coal powder airflow channel; an ammonia channel is formed between the first and second cylinders; a secondary air channel is formed between the second and third cylinders; the inner cavity of the first cylinder is divided into four sections from front to back, namely a first steady flow section, a gradually expanding section, a second steady flow section, and a gradually contracting section, the first and second steady flow sections are cylindrical, the gradually expanding section and the gradually contracting section are truncated cone-shaped, the front end of the gradually expanding section has a large diameter; the front end of the gradually contracting section has a small diameter; a blunt body with a cylindrical front end and a truncated cone is provided in the first cylinder, except for a portion of the rear end of the blunt body located inside and outside the gradually expanding section, the rest of the body is located inside the first steady flow section; swirl blades are connected between the inner wall of the first cylinder and the outer wall of the blunt body; a plurality of guide plates are evenly distributed along the circumferential direction at the front end of the second cylinder. The present invention is suitable for working conditions with a relatively low ammonia mixing ratio, and mainly serves to transition coal-fired boilers from pure coal combustion to high-proportion ammonia-mixed combustion.

Description

Technical Field

[0001] The present invention relates to a burner, in particular to a swirl burner for ammonia-coal mixed combustion and a use method thereof. Background Art

[0002] Coal has consistently dominated my country's energy consumption for many years. my country's energy structure, characterized by being "rich in coal, poor in oil, and limited in gas," means that coal-fired power generation will continue to be the primary source of energy for a long time to come. However, the CO2 produced by coal combustion has contributed to a range of climate-related issues, including intensified droughts, melting glaciers, and frequent wildfires. Therefore, my country's power industry urgently needs to transition to a clean, low-carbon approach to achieve carbon emissions reductions. Reducing carbon emissions from coal-fired power plants, in particular, is crucial for achieving my country's "dual carbon" goals. A blanket elimination of all coal-fired power plants would result in significant economic waste and trigger a series of social and livelihood issues. However, adopting zero-carbon energy alternatives can achieve carbon reductions while retaining existing units.

[0003] As an ideal zero-carbon energy source, hydrogen has received widespread attention. However, its safety cannot be solved in the short term, it is difficult to transport on a large scale, the storage cost is high, and the liquefaction pressure is high. Compared with hydrogen, ammonia, as an ideal zero-carbon energy source, is safer, can be transported on a large scale, has lower storage costs, and has a higher volumetric energy density. Therefore, ammonia-coal co-firing will be one of the important development directions for the green and low-carbon transformation of coal-fired power plants. However, when burning ammonia as the main fuel, there are still some problems. On the one hand, the fuel properties between ammonia and pulverized coal are very different. Moreover, during the co-firing process, ammonia will compete with pulverized coal for O2, affecting the ignition, stable combustion, and combustion of the pulverized coal flame. On the other hand, ammonia contains a large amount of nitrogen, which may cause NO at the furnace outlet. x Emissions are rising rapidly. Coal-fired power plants are facing stricter emission control standards for air pollutants.

[0004] Compared with gaseous fuels such as ammonia, pulverized coal as a solid fuel is more difficult to burn, especially under conditions where the ammonia ratio is small. More attention should be paid to how to ensure the stable combustion of pulverized coal after ammonia mixing and the subsequent NO x Control. Generally speaking, the burner, as the core part of the combustion system, controls the fuel / air mixing process and is the key equipment for achieving fuel ignition and stable combustion. For ammonia-coal co-firing, the burner structure can be designed to flexibly control the local oxygen concentration distribution and the initial reaction environment of ammonia, and rationally organize the fuel / air mixing process, thereby improving fuel combustion characteristics and reducing NO x This is of great significance for achieving clean and low-carbon combustion in coal-fired power plants by adding ammonia. Summary of the Invention

[0005] The present invention aims to solve the technical problems existing in the known technology and provides a swirl burner for ammonia-coal co-firing and a method of using the same.

[0006] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is:

[0007] A swirl burner for ammonia-coal co-firing, comprising first to third cylinders which are sleeved in sequence from the inside to the outside; the inner cavity of the first cylinder forms a coal powder airflow channel; the cavity between the first and second cylinders forms an ammonia gas channel; the cavity between the second and third cylinders forms a secondary air channel; the inner cavity of the first cylinder is divided into four sections from front to back, namely a first steady flow section, a gradually expanding section, a second steady flow section and a gradually contracting section, the first and second steady flow sections are cylindrical, the gradually expanding section and the gradually contracting section are truncated cone-shaped, the front diameter of the gradually expanding section is larger than the rear diameter The front end diameter of the tapered section is smaller than the rear end diameter; a blunt body is provided in the first cylinder, the front end of the blunt body being cylindrical and the rear end being truncated; except for a portion of the rear end of the blunt body located inside and outside the gradually expanding section, the rest of the blunt body is located in the first steady flow section; swirl blades are connected between the inner wall of the first cylinder and the outer wall of the blunt body; a plurality of guide plates with adjustable outward opening angles are uniformly distributed along the circumference of the front end of the second cylinder; the outward opening angle of the guide plates can be adjusted in the range of 0 to 30 degrees, and the plurality of guide plates form a trumpet-shaped enclosure.

[0008] Furthermore, the front end surface of the third cylinder is 3 to 7 mm longer than the front end surface of the second cylinder in the axial direction.

[0009] Furthermore, the outer edge of the front end surface of the bluff body is provided with grooves uniformly distributed along the circumferential direction, and the multiple grooves form a flame stabilizing ring.

[0010] Furthermore, a plurality of axial through holes are evenly distributed along the circumferential direction in the wall of the first cylinder; rear ends of the through holes are connected to the water supply device.

[0011] Furthermore, the length of the first cylinder is 80-100 mm, the inner diameter of the first steady flow section is 26-35 mm, and the length is 40-50 mm; the inner diameter of the second steady flow section is 15-24 mm; the length is 40-50 mm; the length of the gradually expanding section is 15-18 mm; and the length of the gradually contracting section is 10-12 mm.

[0012] Furthermore, the maximum diameter of the frustum in the bluff body is 14-18 mm, and the minimum diameter is 6-10 mm; the length of the cylindrical portion of the bluff body is 20-25 mm, and the length of the frustum portion of the bluff body is 12-16 mm.

[0013] Furthermore, the gap between the first and second cylinders is 0.6-1 mm; the gap between the second and third cylinders is 0.8-1.2 mm.

[0014] Furthermore, the guide plate has a length of 4 to 6 mm along the axial direction of the swirl burner and a thickness of 0.5 to 0.8 mm.

[0015] The present invention also provides several methods for using the above-mentioned swirl burner for ammonia-coal mixed combustion, wherein the swirl burner is used as a pure coal burner and / or an ammonia-coal mixed burner;

[0016] When the swirl burner is used as a pure coal burner, the method includes the following steps:

[0017] The pulverized coal mixed with primary air is injected from the convergent section of the pulverized coal airflow channel, and passes through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of dense and thin air, which entrain the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, the remaining air is divided into internal and external secondary air. The internal secondary air is first injected into the furnace through the ammonia channel. The internal secondary air contacts and burns with the dense pulverized coal airflow at the outlet of the pulverized coal airflow channel. Then, the expansion angle of the guide plate is adjusted to increase the size of the central recirculation zone, allowing the primary air and pulverized coal flow to heat up. Finally, the external secondary air is injected into the furnace through the secondary air channel to achieve complete combustion of the pulverized coal.

[0018] When the swirl burner is used as an ammonia-coal mixed burner, the method comprises the following steps:

[0019] The pulverized coal mixed with the primary air is injected into the pulverized coal airflow channel from the gradually contracting section, passing through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of thick and thin air, which then draw in the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. Then, all the ammonia is directly injected into the furnace from the ammonia channel at one time. The expansion angle of the guide plate is adjusted to prevent the ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO. x ; Finally, the secondary air is sprayed into the furnace through the secondary air channel to achieve complete combustion of coal powder and ammonia.

[0020] Furthermore, when the swirl burner is used as an ammonia-coal mixed burner, the following method steps are also included:

[0021] Fuel grading is used to mix a portion of ammonia with the pulverized coal airflow and then inject it into the pulverized coal airflow channel from the gradually contracting section. It then passes through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of thick and thin gases, allowing the ammonia and pulverized coal to be fully mixed. The high-temperature flue gas in the furnace is then entrained to ignite and burn the pulverized coal. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. The remaining ammonia is then injected into the furnace from the ammonia channel. The flaring angle of the guide plate is adjusted to prevent the ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO. x ; Finally, the secondary air is sprayed into the furnace through the secondary air channel to achieve complete combustion of coal powder and ammonia.

[0022] The advantages and positive effects of the present invention are:

[0023] The present invention discloses a swirl burner for ammonia-coal co-combustion. A bluff body is disposed within a first cylinder. The front end of the bluff body is cylindrical, and the rear end is truncated. Except for a portion of the rear end of the bluff body located inside and outside the gradually expanding section, the rest of the bluff body is located within the first steady-flow section. As the pulverized coal airflow passes through the channel and the bluff body, it is separated into two streams, rich and lean. The outer diameter represents the rich side of the pulverized coal flow, while the inner diameter represents the lean side of the pulverized coal flow. The pulverized coal airflow passes through the swirl blades, creating a swirl, which enhances thermal disturbance and strengthens pulverized coal combustion.

[0024] The outer edge of the front end of the bluff body is provided with grooves evenly distributed along the circumference, forming a flame stabilizing ring. This design increases the wrinkles of the pulverized coal flame surface and strengthens the pulverized coal combustion.

[0025] The water spray device provides H and OH free radicals to the environment, promotes the dehydrogenation reaction of ammonia, and reduces NO generated during the co-combustion process. x .

[0026] The guide plate can flexibly adjust the expansion angle to prevent ammonia from combining with the secondary air prematurely and oxidizing to produce NO. x .

[0027] During the pulverized coal combustion process, the outer concentrated pulverized coal flow will consume a large amount of O2, forming an oxygen-deficient atmosphere. At this time, it will combine with the ammonia at the outlet of the ammonia channel to help the ammonia reduce the NO generated by combustion in the oxygen-deficient atmosphere. x The ammonia-coal mixed swirl burner mainly plays a role in transitioning coal-fired boilers from pure coal combustion to high-proportion ammonia combustion, which is of great significance for the green and low-carbon transformation of future coal-fired power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 An axial cross-sectional view of a swirl burner for ammonia-coal co-firing according to the present invention

[0029] Figure 2 This is a schematic diagram of the three-dimensional structure of a swirl burner for ammonia-coal co-firing according to the present invention.

[0030] Figure 3 This is a front view of a swirl burner for ammonia-coal co-firing according to the present invention.

[0031] In the figure, 1, first cylinder; 2, second cylinder; 3, third cylinder; 4, second steady flow section; 5, first steady flow section; 6, ammonia channel; 7, secondary air channel; 8, guide plate; 9, groove; 10, front end of blunt body; 11, swirl blade; 12, rear end of blunt body; 13, gradually expanding section; 14, gradually converging section; 15, through hole. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0033] In the description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention. The terms "connected" and "connection" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can also be an electrical connection or signal transmission. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0034] See Figures 1 to 3 A swirl burner for ammonia-coal co-firing comprises a first cylinder 1, a second cylinder 2, and a third cylinder 3 which are sequentially sleeved from the inside to the outside; the inner cavity of the first cylinder 1 forms a coal powder airflow channel; the cavity between the first cylinder 1 and the second cylinder 2 forms an ammonia channel 6; the cavity between the second cylinder 2 and the third cylinder 3 forms a secondary air channel 7; the inner cavity of the first cylinder 1 is divided into four sections from front to back, namely a first steady flow section 5, a gradually expanding section 13, a second steady flow section 4, and a gradually converging section 14. The first steady flow section 5 and the second steady flow section 4 are cylindrical, and the gradually expanding section 13 and the gradually converging section 14 are cylindrical. The section 14 is truncated cone-shaped. The front diameter of the expanding section 13 is larger than the rear diameter; the front diameter of the converging section 14 is smaller than the rear diameter. A blunt body is located within the first cylinder 1. The front end of the blunt body is cylindrical and the rear end is truncated cone-shaped. Except for a portion of the rear end of the blunt body located inside and outside the expanding section 13, the rest of the blunt body is located within the first stabilizing section 5. Swirl blades 11 are connected between the inner wall of the first cylinder 1 and the outer wall of the blunt body. Multiple guide plates 8 with adjustable outward opening angles are evenly distributed along the circumference of the front end of the second cylinder 2. The outward opening angle of the guide plates 8 can be adjusted from 0 to 30 degrees. The multiple guide plates 8 form a bell-mouth shape.

[0035] The guide plate 8 can be hinged to the front end of the second cylinder 2 via a rotating shaft so that the outward opening angle can be adjusted. The rotating shaft is connected to the guide plate 8, and the guide plate 8 rotates with the rotating shaft.

[0036] Various transmission and drive structures in the existing technology can be used to drive the rotating shaft to rotate. For example, a motor can be set at the rear end of the swirl burner, and the motor output shaft and the rotating shaft can be connected through a chain transmission structure. The chain is driven by the forward and reverse rotation of the motor, and the chain drives the rotating shaft forward and reverse. The outward opening angle of the guide plate 8 can be controlled by controlling the rotation angle of the motor.

[0037] Alternatively, a swing lever or pendulum wheel may be provided at one or both ends of the rotating shaft, the swing lever or pendulum wheel being perpendicularly connected to the rotating shaft, and the swing lever or pendulum wheel swinging to drive the rotating shaft to rotate. For example, a motor may be provided at the rear end of the swirl burner to drive a fan-shaped wheel. The fan-shaped wheel may be the same shape as the pendulum wheel. One end of two pull ropes may be connected to the two end points of the circumference of the fan-shaped wheel. The other ends of the two pull ropes may be connected to the two end points of the circumference of the pendulum wheel or the two ends of the swing lever. The motor output shaft is connected to the fan-shaped wheel, and the motor's forward and reverse rotation drives the fan-shaped wheel to swing. The pull ropes drive the pendulum wheel or swing lever to swing, thereby driving the rotating shaft forward and reverse. The outward opening angle of the guide plate 8 can be controlled by controlling the rotation angle of the motor.

[0038] Preferably, the front end surface of the third cylinder 3 is 3 to 7 mm longer than the front end surface of the second cylinder 2 in the axial direction.

[0039] Preferably, the outer edge of the front end 10 of the bluff body may be provided with grooves 9 uniformly distributed along the circumferential direction, and the plurality of grooves 9 form a flame stabilizing ring.

[0040] Preferably, a plurality of axial through holes 15 can be evenly distributed along the circumference of the wall of the first cylinder 1; the rear ends of the through holes 15 are connected to the water supply device. The plurality of axial through holes 15 and the water supply device constitute a water spray device.

[0041] Preferably, the length of the first cylinder 1 can be 80-100 mm, the inner diameter of the first steady flow section 5 can be 26-35 mm, and the length can be 40-50 mm; the inner diameter of the second steady flow section 4 can be 15-24 mm; the length can be 40-50 mm; the length of the gradually expanding section 13 can be 15-18 mm; and the length of the gradually contracting section 14 can be 10-12 mm.

[0042] Preferably, the maximum diameter of the truncated cone in the bluff body can be 14-18 mm, and the minimum diameter can be 6-10 mm. The length of the cylindrical portion of the bluff body can be 20-25 mm, and the length of the truncated cone portion of the bluff body can be 12-16 mm.

[0043] Preferably, the gap between the first cylinder 1 and the second cylinder 2 may be 0.6-1 mm; the gap between the second cylinder 2 and the third cylinder 3 may be 0.8-1.2 mm.

[0044] Preferably, the guide plate 8 may have a length of 4 to 6 mm along the axial direction of the swirl burner and a thickness of 0.5 to 0.8 mm.

[0045] The above-mentioned structural lengths all refer to the axial lengths.

[0046] The present invention also provides several methods for using the above-mentioned swirl burner for ammonia-coal mixed combustion, wherein the swirl burner is used as a pure coal burner and / or an ammonia-coal mixed burner;

[0047] When the swirl burner is used as a pure coal burner, the method includes the following steps:

[0048] The pulverized coal mixed primary air is injected from the pulverized coal airflow channel's convergent section 14, passes through the second steady flow section 4, the gradually expanding section 13, and the first steady flow section 5 in sequence, and is separated into two swirls of dense and thin air, which entrain the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, the remaining air is divided into internal and external secondary air, and the internal secondary air is first injected into the furnace through the ammonia channel 6. The internal secondary air contacts and burns with the dense pulverized coal airflow at the outlet of the pulverized coal airflow channel. Then, the expansion angle of the guide plate 8 is adjusted to increase the size of the central recirculation zone, allowing the primary air and pulverized coal flow to heat up. Finally, the external secondary air is injected into the furnace through the secondary air channel 7 to achieve complete combustion of the pulverized coal.

[0049] When the swirl burner is used as an ammonia-coal mixed burner, the method comprises the following steps:

[0050] The pulverized coal mixed with the primary air is injected from the coal pulverized air flow channel through the converging section 14, and sequentially passes through the second steady flow section 4, the expanding section 13, and the first steady flow section 5, where it is separated into two vortexes of thick and thin air, which entrain the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. Then, all the ammonia is directly injected into the furnace from the ammonia channel 6 at one time. The expansion angle of the guide plate 8 is adjusted to prevent the ammonia from combining with the secondary air too early in the early stage of combustion and being oxidized into NO. x Finally, the secondary air is injected into the furnace through the secondary air channel 7 to achieve complete combustion of pulverized coal and ammonia.

[0051] Preferably, when the swirl burner is used as an ammonia-coal mixed burner, the method may further include the following steps:

[0052] Fuel grading is used to mix a portion of ammonia with the pulverized coal airflow and then inject it into the pulverized coal airflow channel from the converging section 14. The mixture passes through the second steady flow section 4, the gradually expanding section 13, and the first steady flow section 5 in sequence, where it is separated into two vortexes of concentrated and diluted ammonia, fully mixing the ammonia and pulverized coal. The high-temperature flue gas in the furnace is entrained, causing the pulverized coal to ignite and burn. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. The remaining ammonia is then injected into the furnace from the ammonia channel 6. The flaring angle of the guide plate 8 is adjusted to prevent the ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO. x Finally, the secondary air is injected into the furnace through the secondary air channel 7 to achieve complete combustion of pulverized coal and ammonia.

[0053] High-temperature flue gas refers to flue gas with a high temperature when discharged, usually above 800 degrees Celsius, and some high-temperature flue gas can even reach 1000 degrees Celsius. Low-temperature flue gas refers to flue gas with a lower temperature when discharged, generally between 200 degrees Celsius and 400 degrees Celsius.

[0054] Water can be sprayed into the furnace using a separate water spray device, such as an annular nozzle connected to a water supply line. Alternatively, multiple axial through-holes 15 can be evenly distributed along the circumference of the wall of the first cylinder 1, with the rear ends of the through-holes 15 connected to the water supply line. The multiple axial through-holes 15 and the water supply line constitute the water spray device.

[0055] The structure, workflow and working principle of the present invention are further described below with reference to a preferred embodiment of the present invention:

[0056] A swirl burner for ammonia-coal co-firing, comprising first to third cylinders 3 which are sequentially sleeved from the inside to the outside; the inner cavity of the first cylinder 1 forms a coal powder airflow channel; the cavity between the first and second cylinders forms an ammonia channel 6; the cavity between the second and third cylinders forms a secondary air channel 7; the inner cavity of the first cylinder 1 is divided into four sections, which are, from front to back, a first steady flow section 5, a gradually expanding section 13, a second steady flow section 4 and a gradually contracting section 14; the first and second steady flow sections are cylindrical, the gradually expanding section 13 and the gradually contracting section 14 are frustum-shaped, the front end diameter of the gradually expanding section 13 is larger than the rear end diameter; the front end diameter of the gradually contracting section 14 is smaller than the rear end diameter; that is, the inner cavity diameter of the first steady flow section 5 is larger than the inner cavity diameter of the second steady flow section 4.

[0057] A bluff body is positioned within the first cylinder 1. The front end 10 of the bluff body is cylindrical, and the rear end 12 is a truncated cone. Except for a portion of the rear end located within the diverging section 13, the remainder of the bluff body is located within the first stabilizing section 5. Swirling vanes 11 are connected between the inner wall of the first cylinder 1 and the outer wall of the bluff body. Multiple guide plates 8 with adjustable outward opening angles are evenly distributed along the circumference of the front end of the second cylinder 2. The outward opening angle of the guide plates 8 can be adjusted from 0 to 30 degrees. The multiple guide plates 8 form a bell-mouth shape. This means that the inner diameter of the first stabilizing section 5 is larger than that of the second stabilizing section 4.

[0058] The cylindrical channel for pulverized coal airflow comprises a first steady-flow section 5, a gradually expanding section 13, a second steady-flow section 4, and a gradually converging section 14. These sections are used for conveying the pulverized coal airflow and separating the dense and thin streams. The gradually converging section 14 converges the pulverized coal flow, the steady-flow section stabilizes the airflow, and the gradually expanding section 13 enhances radial diffusion of the pulverized coal flow.

[0059] The front end 10 of the bluff body is a cylinder, and the rear end 12 of the bluff body is a truncated cone. The front end 10 of the bluff body is used for stabilizing the flow, and the rear end 12 of the bluff body is used for enhancing the radial diffusion of the pulverized coal flow.

[0060] The outer edge of the front end 10 of the bluff body is provided with a plurality of grooves 9 uniformly distributed along the circumference, and the plurality of grooves 9 form a flame stabilizing ring for enhancing combustion;

[0061] Swirl blades 11 are provided on the circumference of the bluff body to enhance the radial diffusion of the pulverized coal flow, while forming a swirl to enhance thermal disturbance and strengthen the combustion of the pulverized coal.

[0062] The inner cavity of the first cylinder 1 has a length of 90 mm, a minimum diameter of 20 mm and a maximum diameter of 30 mm.

[0063] The maximum diameter of the blunt body is 16 mm, and the minimum diameter is 8 mm. The length of the cylindrical portion of the blunt body can be 20 to 25 mm, and the length of the frustum portion of the blunt body can be 12 to 16 mm.

[0064] The second cylinder 2 has a length of 90 mm and a wall thickness of 0.8 mm.

[0065] The third cylinder 3 has a length of 95 mm and a wall thickness of 1 mm.

[0066] The gap between the first and second cylinders is 0.8 mm; the gap between the second and third cylinders is 1 mm.

[0067] Twenty axial through holes 15 are evenly distributed along the circumference of the first cylinder 1. The rear ends of the through holes 15 are connected to the water supply device. The diameter of the through holes 15 is 0.6 mm.

[0068] The guide plate 8 has a length of 4 mm and a thickness of 0.6 mm along the axial direction of the swirl burner.

[0069] The pulverized coal airflow channel adopts a design similar to that of a Venturi tube. When the pulverized coal airflow passes through the channel and the blunt body, it is separated into two streams of dense and thin airflows. The outer diameter is the dense side pulverized coal flow, and the inner diameter is the thin side pulverized coal flow. The pulverized coal airflow passes through the swirl blades 11 to form a swirl, which enhances thermal disturbance and strengthens the combustion of pulverized coal. The flame stabilizing ring increases the wrinkles of the pulverized coal flame surface and strengthens the combustion of pulverized coal. During the pulverized coal combustion process, the combustion of the outer dense pulverized coal flow consumes a large amount of O2, forming an oxygen-deficient atmosphere. At this time, it combines with the ammonia at the outlet of the ammonia channel 6, which helps the ammonia to reduce the NO generated by combustion in the oxygen-deficient atmosphere. x The guide plate 8 can flexibly adjust the expansion angle to prevent ammonia from combining with the secondary air too early and being oxidized to produce NO. x The water supply system sprays water into the furnace through the axial through hole 15 in the wall of the first cylinder 1 to provide H and OH free radicals to the environment.

[0070] The swirl burner can be used as a pure coal burner and / or an ammonia-coal mixed burner.

[0071] When the swirl burner is used as a pure coal burner, the method includes the following steps:

[0072] The pulverized coal mixed primary air is injected from the pulverized coal airflow channel's convergent section 14, passes through the steady flow section, the diverging section 13, the bluff body's rear end 12, and the bluff body's front end 10 in sequence, and is separated into two swirls of thick and thin air, which draw in the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, the remaining air is divided into internal and external secondary air, and the internal secondary air is first injected into the furnace through the ammonia channel 6. The internal secondary air contacts and burns with the concentrated pulverized coal airflow at the outlet of the pulverized coal airflow channel, consuming oxygen and suppressing the formation of fuel-type NO in the early stage of pulverized coal combustion. x Then, the expansion angle of the guide plate 8 is adjusted to increase the size of the central recirculation zone, so that a large amount of high-temperature flue gas flows back to the burner outlet, thereby increasing the turbulence and pulsation level of the outlet airflow, strengthening the heat and mass exchange between the airflows, and raising the temperature of the primary air pulverized coal flow, which is very beneficial to the ignition and stable combustion of the pulverized coal; finally, the external secondary air is injected into the furnace through the secondary air channel 7 to promote the mixing of the unburned materials remaining in the reduction zone with the air, thereby achieving complete combustion of the pulverized coal;

[0073] When the swirl burner is used as an ammonia-coal mixed burner, the method comprises the following steps:

[0074] No fuel grading is adopted; the pulverized coal mixed with the primary air is injected into the pulverized coal airflow channel from the convergent section 14, and passes through the steady flow section, the gradually expanding section 13, the blunt body rear end 12, and the blunt body front end 10 in sequence, and is separated into two vortexes of thick and thin, which suck in the high-temperature flue gas in the furnace, so that the pulverized coal quickly ignites and burns; at this time, the flame stabilizing ring is conducive to improving the stability of the pulverized coal flame; then, the water supply system is used to spray water into the furnace through the axial through hole 15 in the wall of the first cylinder 1 to increase the concentration of H and OH free radicals in the environment; then, all the ammonia is directly injected into the furnace from the ammonia channel 6 at one time; since the combustion of the thick pulverized coal airflow at the outer diameter of the pulverized coal airflow channel outlet consumes a lot of oxygen, forming an oxygen-deficient area, the addition of ammonia helps to reduce the fuel-type NO in the early stage of combustion. x Adjust the flaring angle of the guide plate 8 to prevent ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO x Finally, the secondary air is injected into the furnace through the secondary air channel 7 to promote the mixing of the unburned materials remaining in the reduction zone with the air, thereby achieving complete combustion of the pulverized coal and ammonia.

[0075] By adopting fuel grading, a part of ammonia is mixed with the pulverized coal airflow and then sprayed into the pulverized coal airflow channel from the converging section 14, and sequentially passes through the steady flow section, the gradually expanding section 13, the rear end 12 of the blunt body, and the front end 10 of the blunt body, and is separated into two swirls of thick and thin, so that the ammonia and pulverized coal are mixed more fully; since the ignition of ammonia is earlier than that of the pulverized coal, the combustion of ammonia helps to release the volatile matter of the pulverized coal and promotes the subsequent ignition of the pulverized coal; at this time, the flame stabilizing ring is conducive to improving the stability of the flame; then, the water supply system is made to spray water into the furnace through the axial through hole 15 in the wall of the first cylinder 1 to increase the concentration of H and OH free radicals in the environment; then, the remaining ammonia is sprayed into the furnace from the ammonia channel 6; ammonia is used to reduce NO in an oxygen-deficient environment x Adjust the flaring angle of the guide plate 8 to prevent ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO x Finally, the secondary air is injected into the furnace through the secondary air channel 7 to promote the mixing of the unburned materials remaining in the reduction zone with the air, thereby achieving complete combustion of the pulverized coal and ammonia.

[0076] The first to third cylinders, blunt bodies, annular nozzles, water supply pipes, water spraying devices, guide plates, etc. can all adopt applicable components and structures in the existing technology, or adopt components in the existing technology and adopt conventional technical means to construct.

[0077] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of the patent of the present invention cannot be limited by these embodiments alone. That is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the scope of the patent of the present invention.

Claims

1. A swirl burner for ammonia-coal co-firing, characterized in that: The invention comprises first to third cylinders that are sequentially sleeved from the inside out. The inner cavity of the first cylinder forms a coal powder airflow channel; the cavity between the first and second cylinders forms an ammonia channel; and the cavity between the second and third cylinders forms a secondary air channel. The inner cavity of the first cylinder is divided into four sections from front to back: a first steady flow section, a gradually expanding section, a second steady flow section, and a gradually contracting section. The first and second steady flow sections are cylindrical, while the gradually expanding and gradually contracting sections are frustum-shaped. The front end diameter of the gradually expanding section is larger than the rear end diameter; the front end diameter of the gradually contracting section is smaller than the rear end diameter. A blunt body is disposed within the first cylinder. The front end of the blunt body is cylindrical and the rear end is frustum-shaped. Except for a portion of the rear end of the blunt body located inside and outside the gradually expanding section, the rest of the blunt body is located within the first steady flow section. Swirl blades are connected between the inner wall of the first cylinder and the outer wall of the blunt body. A plurality of guide plates with adjustable outward opening angles are uniformly distributed circumferentially at the front end of the second cylinder. The outward opening angle of the guide plates can be adjusted within a range of 0 to 30 degrees, and the plurality of guide plates form a bell-mouth shape.

2. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The front end surface of the third cylinder is 3 to 7 mm longer in the axial direction than the front end surface of the second cylinder.

3. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The outer edge of the front end surface of the bluff body is provided with grooves uniformly distributed along the circumference, and the multiple grooves form a flame stabilizing ring.

4. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: A plurality of axial through holes are evenly distributed along the circumferential direction in the wall of the first cylinder; rear ends of the through holes are communicated with the water supply device.

5. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The length of the first cylinder is 80-100 mm, the inner diameter of the first steady flow section is 26-35 mm, and the length is 40-50 mm; the inner diameter of the second steady flow section is 15-24 mm, and the length is 40-50 mm; the length of the gradually expanding section is 15-18 mm; and the length of the gradually contracting section is 10-12 mm.

6. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The maximum diameter of the frustum in the blunt body is 14 to 18 mm, and the minimum diameter is 6 to 10 mm; the length of the cylindrical part of the blunt body is 20 to 25 mm, and the length of the frustum part of the blunt body is 12 to 16 mm.

7. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The gap between the first and second cylinders is 0.6-1 mm; the gap between the second and third cylinders is 0.8-1.2 mm.

8. The swirl burner for ammonia-coal co-firing according to claim 1, characterized in that: The length of the guide plate along the axial direction of the swirl burner is 4-6 mm, and the thickness is 0.5-0.8 mm.

9. A method for using the swirl burner for ammonia-coal co-firing according to any one of claims 1 to 8, characterized in that: The swirl burner is used as a pure coal burner and / or an ammonia-coal mixed burner; When the swirl burner is used as a pure coal burner, the method includes the following steps: The pulverized coal mixed with primary air is injected from the convergent section of the pulverized coal airflow channel, and passes through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of dense and thin air, which entrain the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, the remaining air is divided into internal and external secondary air. The internal secondary air is first injected into the furnace through the ammonia channel. The internal secondary air contacts and burns with the dense pulverized coal airflow at the outlet of the pulverized coal airflow channel. Then, the expansion angle of the guide plate is adjusted to increase the size of the central recirculation zone, allowing the primary air and pulverized coal flow to heat up. Finally, the external secondary air is injected into the furnace through the secondary air channel to achieve complete combustion of the pulverized coal. When the swirl burner is used as an ammonia-coal mixed burner, the method comprises the following steps: The pulverized coal mixed with the primary air is injected into the pulverized coal airflow channel from the gradually contracting section, passing through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of thick and thin air, which then draw in the high-temperature flue gas in the furnace, causing the pulverized coal to ignite and burn. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. Then, all the ammonia is directly injected into the furnace from the ammonia channel at one time. The expansion angle of the guide plate is adjusted to prevent the ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO. x ; Finally, the secondary air is sprayed into the furnace through the secondary air channel to achieve complete combustion of coal powder and ammonia.

10. The method for using the swirl burner for ammonia-coal co-firing according to claim 9, characterized in that: When the swirl burner is used as an ammonia-coal mixed burner, the method further includes the following steps: Fuel grading is used to mix a portion of ammonia with the pulverized coal airflow and then inject it into the pulverized coal airflow channel from the gradually contracting section. It then passes through the second steady flow section, the gradually expanding section, and the first steady flow section in sequence, where it is separated into two vortexes of thick and thin gases, allowing the ammonia and pulverized coal to be fully mixed. The high-temperature flue gas in the furnace is then entrained to ignite and burn the pulverized coal. Subsequently, water is sprayed into the furnace to increase the concentration of H and OH free radicals in the environment. The remaining ammonia is then injected into the furnace from the ammonia channel. The flaring angle of the guide plate is adjusted to prevent the ammonia from combining with the secondary air too early in the early stages of combustion and being oxidized into NO. x ; Finally, the secondary air is sprayed into the furnace through the secondary air channel to achieve complete combustion of coal powder and ammonia.

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