W-shaped boiler burner based on pulverized coal particle size separation

Abstract

The invention aims to provide a W-shaped boiler burner based on pulverized coal particle size separation, belongs to the technical field of pulverized coal combustion, and can solve the problems that coarse pulverized coal particles are located on the periphery of the burner and fine pulverized coal particles are located in the center due to airflow rotation inertia of the W-shaped boiler burner; and the problems of delayed pulverized coal ignition, low combustion efficiency, high NOx emission and the like are solved. A vertical downward injection type structure is adopted, and a cross deflection flow guide structure is arranged in the combustor, so that pulverized coal is finally distributed at a contraction nozzle of the combustor in the mode of'centralized injection of center coarse powder and coating of outer layer fine powder '. By means of the structure, fine pulverized coal can be preferentially ignited in a hearth with the low temperature to establish a stable high-temperature field, central coarse-particle pulverized coal is promoted to be completely burnt out, the burning stability of inferior coal and wide-particle-size pulverized coal is remarkably improved, and the loss of unburnt carbon and the generation amount of NOx are effectively reduced.

Description

A W-type boiler burner based on pulverized coal particle size sorting Technical Field

[0001] This invention belongs to the field of pulverized coal combustion technology, specifically relating to a W-type boiler burner based on pulverized coal particle size sorting. Background Technology

[0002] In the pulverized coal combustion process, the combustion efficiency of the burner directly affects the boiler's operating efficiency and environmental performance. W-type boiler burners often employ a single-channel direct-flow structure, lacking proper sorting and distribution control of pulverized coal particle size, resulting in the following problems: 1. Ignition delay: The mixture of coarse and fine pulverized coal particles prevents fine particles from preferentially accumulating in easily ignitable areas, leading to a long ignition delay, poor ignition stability, and a tendency for flameout and reignition during startup; 2. Low combustion efficiency: Coarse pulverized coal particles suffer from insufficient ambient temperature and short combustion time, resulting in a high rate of unburned carbon loss; 3. Higher pollutant emissions: Inappropriate combustion conditions increase NOx emissions. x The generation of nitrogen oxides (NOx) and unburned coal powder also exacerbate pollutant emissions, failing to meet the NOx emission standards of GB 13223-2011 "Emission Standard of Air Pollutants for Thermal Power Plants". x Emissions ≤500mg / Nm 3 Requirements.

[0003] For low-quality coal (such as low-volatile, high-ash coal) and pulverized coal with a wide particle size distribution, the burner generally adopts a single-channel direct-flow structure. This results in mixed flow of pulverized coal particles, a high measured ignition delay time, and a large unburned carbon loss rate, leading to high NO₂ levels. x Large emissions make it difficult to balance combustion efficiency and cleanliness. Summary of the Invention

[0004] This invention addresses the problems of ignition delay, low combustion efficiency, and high pollutant emissions caused by the pulverized coal particle size distribution in W-type boiler burners. It provides a W-type boiler burner based on pulverized coal particle size sorting. Through an innovative particle size sorting-directional distribution-stage combustion design, and by using centrifugal pre-sorting at the inlet bend and precise distribution through internal cross-guide plates, it achieves the effect of preferential ignition of fine pulverized coal in the outer ring and deep penetration combustion of coarse pulverized coal in the inner ring, thereby improving combustion stability and economy while reducing pollutant emissions.

[0005] The present invention adopts the following technical solution: a W-type boiler burner based on pulverized coal particle size sorting, comprising a burner shell, an inlet section at one end of the burner shell, and a sorting and recombining section and a nozzle section arranged vertically inside the burner shell; the inlet section, the sorting and recombining section and the nozzle section are connected in sequence; the inlet section includes a horizontally arranged inlet straight pipe section and an inlet elbow at a downward 90 degrees connected thereto; the sorting and recombining section includes an inner ring channel cylinder located inside the burner shell, the inner ring channel cylinder being coaxially suspended with the vertical section of the burner shell, and its diameter and length being adapted to the boiler primary air volume and pulverized coal combustion characteristics; the inner ring channel cylinder radially divides the internal flow channel of the burner into annular areas of an outer ring channel and an inner ring channel that are not interconnected; the outer ring channel and the inner ring channel form a sealed structure, which can stably separate independent flow channels to prevent the pulverized coal particles inside them from mixing during the flow process.

[0006] The outer wall of the inlet elbow serves as the coarse powder inlet channel, and the central injection area of ​​the nozzle section serves as the coarse powder outlet channel. The inner side and center of the inlet elbow serve as the fine powder inlet channel, and the outer annular area serves as the fine powder outlet channel. The centrifugal effect of the inlet elbow on the coarse and fine coal particles, combined with the subsequent cross-flow guiding structure, achieves directional classification of the coal powder. The inlet elbow structure utilizes the centrifugal inertial difference between the gas and solid two-phase flows, causing large-diameter coarse coal powder to accumulate due to inertia in the outer annular region corresponding to the outer arc sidewall of the inlet elbow, forming a dense-phase coarse powder flow. Small-diameter fine coal powder adheres to the center and inner arc of the elbow with the airflow. The inner ring region corresponding to the side forms a fine powder flow; the transition area connecting the inlet elbow and the inner ring channel cylinder is provided with a cross-sorting and guiding assembly, which includes a guide plate one for deflecting from the outside to the inside and a guide plate two for deflecting from the inside to the outside; one end of the guide plate one is connected to the inner wall of the burner shell, and the other end is inserted into the inlet of the inner ring channel at an inward tilt. Its tilt angle is adapted to the inertial trajectory of the coarse coal powder, forming a intercepting and scooping structure, which guides the dense phase coarse powder flow located in the outer ring region of the outlet section of the inlet elbow into the central inner ring region of the nozzle section outlet section.

[0007] One end of the guide plate 2 is connected to the bottom inlet edge of the inner ring channel cylinder, and the other end extends outward to the inner arc side flow channel of the inlet bend, forming a flow splitting structure. This guides the fine powder flow located in the inner ring area of ​​the outlet section of the inlet bend to the outer ring area of ​​the nozzle outlet section, thereby forming a combustion mode at the burner outlet where the inner ring is composed of high momentum coarse coal powder and the outer ring is composed of easily ignitable fine coal powder.

[0008] In the nozzle section, the inner ring channel forms a concentrated injection zone for coarse pulverized coal, and the outer ring channel forms a coating layer for fine pulverized coal, achieving a distribution of "inner layer coarse powder - outer layer fine powder". The inner ring channel forms a concentrated injection zone for high-momentum coarse pulverized coal to prolong its residence time in the furnace, and the outer ring channel forms a coating layer for high-concentration fine pulverized coal, enabling the fine pulverized coal to be preferentially ignited and establish a stable high-temperature field in the furnace with a lower temperature, thus promoting the complete combustion of the central coarse pulverized coal particles.

[0009] The cross-sectional dimensions of the flow channels in the outer and inner ring regions are designed with an adjustable range. To meet the requirements of sorting and combustion dynamics for different coal types, the radial width or equivalent diameter of each channel relative to the diameter of the burner inlet straight pipe section is defined as follows: the radial width of the coarse powder inlet channel is 0.15-0.3 times the diameter of the inlet straight pipe section; the equivalent diameter of the fine powder inlet channel is 0.4-0.7 times the diameter of the inlet straight pipe section; the diameter of the coarse powder outlet channel is 0.35-0.55 times the diameter of the inlet straight pipe section to form a high-speed jet; the radial width of the fine powder outlet channel is 0.1-0.25 times the diameter of the inlet straight pipe section to form a stable low-speed coal powder ring.

[0010] The above-mentioned size matching is determined based on the volatile matter characteristics and particle size distribution range of the coal type to ensure that the fine powder splitting rate and coarse powder concentration ratio meet the combustion requirements.

[0011] Furthermore, a coarse pulverized coal triangular guide plate is provided at the inner inlet of the inner ring channel. The cross-section of the coarse pulverized coal triangular guide plate is wedge-shaped or triangular pyramidal. The tip of the coarse pulverized coal triangular guide plate faces the direction of the incoming flow of coarse pulverized coal. This is used to break up and rectify the dense phase coarse pulverized coal airflow introduced into the inner ring channel, reduce local resistance, and prevent pulverized coal from accumulating at the inlet.

[0012] Furthermore, the inner ring channel is equipped with a fine coal powder conical guide plate. The fine coal powder conical guide plate is located on the central axis of the inner ring channel cylinder, in the fine coal powder inlet channel area. Its cross-section is a streamlined spindle or cone structure. It is located in the diffuser section of the inner ring channel to further constrain the airflow area in the inner ring channel. It also works with the fine coal powder conical guide plate to push the central fine powder to the outer channel, thereby increasing the injection momentum of coarse coal powder.

[0013] Furthermore, the nozzle section outlet is a contraction structure, which cooperates with the outlet end of the inner ring channel cylinder to form a contraction nozzle shape. This is used to keep the fine coal powder output from the outer ring area and the coarse coal powder output from the inner ring area in a stratified state when leaving the nozzle and inject them into the furnace. This causes the fine coal powder airflow in the outer ring channel to slightly contract towards the central axis when it is ejected, forming an air-coal ring that surrounds the jet of the inner ring channel.

[0014] Furthermore, the guide plate is tangent to the outer streamline of the inlet bend and inclined inward at an angle of 20-45° to ensure that coarse coal powder is smoothly introduced into the inner channel. This angle is positively correlated with the increase of the average particle size of the coal powder to ensure the collection efficiency of coarse coal powder.

[0015] Furthermore, the second guide plate is tangent to the inner streamline of the inlet bend and inclined outward at an angle of 20-45°. This angle is set to minimize the resistance loss of fine coal powder flow and ensure the proportion of fine coal powder smoothly introduced into the outer ring channel.

[0016] Furthermore, the burner shell, inner ring channel cylinder, fine coal powder conical guide plate, coarse coal powder triangular guide plate, guide plate one and guide plate two are all made of high temperature resistant alloy steel, and are coated with wear-resistant ceramic coating on the coal powder scouring surface.

[0017] This invention addresses the problems of ignition delay, low combustion efficiency, and high pollutant emissions caused by the pulverized coal particle size distribution in W-type pulverized coal boilers in power plants. It designs a pulverized coal particle size sorting burner, which is completely different from other burners in terms of structure and operation. This burner uses a flow guiding structure to divide the burner interior into inner and outer ring channels, realizing pulverized coal particle size sorting. It can effectively solve many problems such as low combustion efficiency, and has the advantages of low cost, simple operation, and strong practicality.

[0018] The burner is used in a W-type flame boiler. The distribution of "inner layer coarse powder - outer layer fine powder" allows the fine coal powder to preferentially contact the high-temperature environment and oxygen in the outer ring and ignite, forming a stable fire source. At the same time, it gives the inner layer coarse coal powder a high axial momentum, allowing it to penetrate deep into the furnace and then turn back, thus prolonging the residence time of the coarse coal powder in the furnace.

[0019] The "inner layer coarse powder - outer layer fine powder" distribution in the nozzle section allows the fine coal powder to preferentially contact the high-temperature environment and oxygen in the outer ring and ignite, forming a stable ignition source. At the same time, the coarse coal powder in the inner layer is enveloped by the high-temperature environment generated by the combustion of the outer layer, ensuring that the coarse coal powder is fully burned.

[0020] As the coarse pulverized coal flows along the W-shaped furnace path, its residence time in the furnace is extended. Combined with the continuous high-temperature environment provided by the combustion of the outer layer of fine pulverized coal, the burnout rate of the coarse pulverized coal is improved.

[0021] The burner is suitable for low-volatile coal with a volatile matter content ≤10% or high-ash coal with an ash content ≥30%, and is also suitable for coal powder with a wide particle size range of 10-200μm. The burner's structure reduces the initial combustion temperature through the rapid ignition of the outer layer of fine powder, thereby suppressing thermal NOx. x The generation of NO x Emissions have decreased.

[0022] In actual combustion, fine coal powder can preferentially contact the environment and oxygen in the outer ring when the furnace temperature is relatively low. Utilizing its large specific surface area and low ignition temperature, it is rapidly ignited and forms a stable annular fuse, effectively solving the ignition delay problem of traditional burners. Simultaneously, it suppresses thermal NOx by reducing the peak temperature at the initial stage of combustion. x The generation of the coarse pulverized coal is achieved by the jet of coarse pulverized coal ejected from the inner channel being enveloped by the outer flame. Utilizing its high axial momentum, the jet penetrates deep into the furnace, flowing along the "downward-returning" path of the W-shaped flame, significantly extending the combustion path of the coarse pulverized coal. This staged combustion mode, characterized by "stable combustion and combustion assistance in the outer layer, and deep penetration and burnout in the inner layer," ensures that the coarse pulverized coal particles are fully burned within sufficient heat and time, greatly reducing the carbon content of fly ash. It is particularly suitable for efficient and clean combustion of low-quality coal (low volatile matter, high ash content) and pulverized coal with a wide particle size distribution (10-200μm).

[0023] The beneficial effects of this invention are as follows: 1. Significantly improved sorting efficiency: It innovatively utilizes the "elbow segregation" phenomenon commonly found in engineering as the sorting driving force. Through the precise coordination of the elbow centrifugal force and the cross guide plates, the separation efficiency of coarse and fine powders is high, and the flow field transition is smooth with low resistance loss.

[0024] 2. Significantly enhanced ignition stability: A "fine powder coating" structure is formed at the burner outlet. The high-concentration fine coal powder in the outer ring has a large specific surface area, which allows it to ignite rapidly upon contact with the high-temperature flue gas in the furnace, forming a stable annular fuse. This effectively solves the problems of difficult ignition and easy flameout in W-type flame boilers.

[0025] 3. Improved combustion efficiency and burnout rate: A "deep-penetrating inner layer of coarse coal powder" jet is formed at the center of the burner. The inner ring of coarse coal powder has high momentum, enabling it to penetrate the airflow stagnation zone and reach deep into the furnace, flowing along the W-shaped flame path with a longer residence time. Under the continuous high temperature provided by the outer layer of fine coal powder, the coarse coal powder is fully burned, significantly reducing the carbon content of fly ash.

[0026] 4. Low NOx emissions: Through rich-lean combustion and staged combustion mechanisms, the rapid ignition of fine powder reduces the peak temperature in the initial stage of combustion. Combined with the design of the oxygen-deficient combustion zone, it effectively suppresses thermal NOx emissions. x The generation of NO x Emissions are reduced compared to traditional burners.

[0027] 5. Reliable structure, wear-resistant and durable: Key internal components (such as guide plates and inner cylinders) are made of heat-resistant alloy steel and coated with wear-resistant ceramic coating; in particular, the design of the triangular guide plate for coarse coal powder effectively solves the wear and dust accumulation problem at the airflow bifurcation point, and meets the long-term operation requirements of low-quality coal.

[0028] 6. Strong adaptability: Targeting the characteristics of low-quality coal (difficult to ignite and burn completely) and wide-particle-size coal powder (large differences in particle size), it achieves efficient and stable combustion through particle size classification combustion control, making it applicable to a wider range of applications. Attached Figure Description

[0029] Figure 1 is a schematic front view of the W-type boiler burner for pulverized coal particle size sorting; Figure 2 is a schematic diagram of section AA of Figure 1; Figure 3 is a schematic diagram of section BB of Figure 1; Figure 4 is a schematic diagram of section CC of Figure 1; Figure 5 is a schematic diagram of section DD of Figure 1; Wherein: 1-inlet straight pipe section; 2-inlet elbow; 3-burner shell; 4-contraction structure; 5-fine pulverized coal conical guide plate; 6-inner ring channel cylinder; 7-guide plate one; 8-outer ring channel; 9-inner ring channel; 10-coarse pulverized coal triangular guide plate; 11-guide plate two; M1-coarse powder inlet channel; N1-fine powder inlet channel; M2-coarse powder outlet channel; N2-fine powder outlet channel. Detailed Implementation

[0030] The invention will be further described with reference to the accompanying drawings.

[0031] As shown in the figure, the W-type boiler burner based on pulverized coal particle size sorting provided by the present invention consists of an inlet section, a sorting and recombining section, and a nozzle section, and adopts a vertical downward injection structure as a whole. In terms of structural composition, the burner inlet section consists of a horizontal inlet straight pipe section 1 and an inlet elbow 2 that is smoothly connected to it at a downward 90 degrees. The inlet elbow 2, as a connecting component, uses its geometric features to act as a primary centrifugal separator, as shown in the CC section of Figure 4 (located at the transition between the outlet of the inlet elbow 2 and the inlet straight pipe section 1). At this time, under the centrifugal force of the inlet elbow 2, the pulverized coal exhibits natural classification in the radial direction: a large number of coarse particles are accumulated in the outer ring area outside the inlet elbow 2, which is defined as the coarse powder inlet channel M1; fine particles are accumulated in the inner ring area inside the elbow and in the center, which is defined as the fine powder inlet channel N1. The main structure of the burner consists of a burner shell 3, inside which an inner ring channel cylinder 6 is coaxially suspended. The inner ring channel cylinder 6 strictly divides the internal flow channel of the burner radially into an outer ring channel 8 and an inner ring channel 9 that are not interconnected. The two channels are responsible for the independent conveying of fine powder and coarse powder, respectively.

[0032] To achieve precise coal powder recombination, this invention incorporates a cross-sorting and guiding assembly. This includes a guide plate 7 for inward deflection and a guide plate 11 for outward deflection. Specifically, one end of the inward deflecting guide plate 7 is connected to the top inner wall of the burner housing 3, while the other end is inserted downwards at the inlet of the inner ring channel 9. Its installation angle is designed to be 20-45°, forming a "blocking bucket" for the coarse powder layer at the upper part of the channel. The corresponding outward deflecting guide plate 11 has one end connected to the bottom inlet edge of the inner ring channel cylinder 6, and the other end extending outwards at an angle to the inner arc side of the inlet bend 2, forming a "diverting slope" for the fine powder layer at the lower part of the channel, blocking the fine powder from entering the inner ring.

[0033] The first guide plate 7 and the second guide plate 11 can be set with a Z-division structure along the circumference, which is determined based on actual application requirements. The specific value of Z can be flexibly adjusted based on the actual operating parameters of the boiler. The adjustment basis includes, but is not limited to, the boiler load range, the particle size distribution characteristics of pulverized coal, the cross-sectional area of ​​the furnace and the heat load requirements of the combustion zone, without being limited by a fixed number of divisions.

[0034] As shown in Figures 2 and 3, in order to optimize the flow field, a coarse pulverized coal triangular guide plate 10 is provided at the inlet section of the inner ring channel 9, with its tip facing the airflow to separate the dense phase coarse powder; a streamlined fine pulverized coal conical guide plate 5 is provided on the central axis inside the inner ring channel 9, which, together with the contraction structure 4 at the burner outlet at the end, is used to accelerate and concentrate the coarse powder jet.

[0035] To ensure the durability of the equipment under harsh operating conditions, the burner shell 3, the inner ring channel cylinder 6, and the internal flow guiding components are all made of heat-resistant alloy steel, and wear-resistant ceramic coatings with a thickness of 0.5-1mm are sprayed on the outer wall of the inlet elbow 2, the windward side of the first flow guide plate 7 and the second flow guide plate 11, and other easily worn parts.

[0036] The working principle and gas-solid flow process of this invention are as follows: The primary airflow carrying coal powder with a wide particle size distribution enters the inlet bend 2 through the inlet straight pipe section 1. When the gas-solid two-phase flow passes through a 90-degree bend, a strong centrifugal effect is generated: the coarse coal powder with a larger particle size and heavier mass, due to its large inertia, cannot turn in time and flows towards the outer circumferential wall of the inlet bend 2, forming a dense phase coarse powder flow; while the fine coal powder with a smaller particle size and lighter mass has good following properties and mainly flows in the central area of ​​the inlet bend 2, forming a fine powder flow. Subsequently, the dense phase coarse powder flow is guided into the inner ring channel 9 in the center by the guide plate 7 which is deflected "from the outside to the inside". During this period, the airflow is broken by the coarse coal powder triangular guide plate 10 to prevent accumulation; the fine powder flow, guided by the guide plate 11 which is deflected "from the inside to the outside", smoothly bypasses the inner ring inlet and is diverted to the outer ring channel 8.

[0037] The coarse pulverized coal ejected from the inner ring channel 9 forms a high-momentum, high-concentration central jet. This jet is highly rigid and can penetrate the stagnant airflow zone at the bottom of the furnace, flowing along the "downward-returning" path of the W-shaped flame. This prolongs the residence time of coarse particles in the furnace, ensuring complete combustion. Simultaneously, the fine pulverized coal ejected from the outer ring channel 8 forms a high-concentration annular coating at the outlet. During combustion, the outer ring fine pulverized coal, due to its large specific surface area and location in the low-velocity zone, preferentially contacts the high-temperature environment and oxygen, resulting in a lower ignition temperature compared to the mixed pulverized coal. This allows for the rapid establishment of a stable annular flame, providing a continuous high-temperature ignition source for the inner ring coarse pulverized coal. This "coarse inside, fine outside" distribution pattern not only completely solves the problems of delayed ignition and easy flameout in W-type boilers but also effectively suppresses thermal NO through the reducing atmosphere formed by the rapid oxygen consumption of the outer layer and the overall low-temperature combustion characteristics. x The generation of fly ash will be controlled and the carbon content will be reduced.

[0038] In actual operation, after the pulverized coal gas flow enters the burner inlet, it passes through the guide structure. Coarse pulverized coal particles enter the inner channel and accumulate in the central area, while fine pulverized coal particles enter the outer channel and diffuse outwards. After forming the above distribution, it enters the furnace for combustion. During combustion, the fine pulverized coal preferentially contacts the high-temperature environment and oxygen in the outer ring, and its ignition temperature is much lower than that of traditional mixed pulverized coal. This not only results in a faster ignition speed but also forms a stable and persistent ignition source, completely solving the problem of burner ignition delay. At the same time, the low-temperature ignition mode reduces the initial and peak combustion temperatures, effectively suppressing thermal NOx. x The generation of coarse pulverized coal is reduced, thus decreasing pollutant emissions. The inner layer of coarse pulverized coal is enveloped by the high-temperature environment generated by the outer combustion layer. Combined with the unique structure of the W-shaped boiler furnace, the coarse pulverized coal flows along a W-shaped path. This flow path significantly extends the combustion path and residence time of the coarse pulverized coal within the furnace, allowing sufficient time for the coarse pulverized coal particles to contact heat and oxygen, ensuring complete combustion and significantly reducing fly ash carbon content and unburned carbon loss. This design significantly improves ignition stability and combustion efficiency, effectively reducing unburned carbon loss and NOx emissions. x This invention, particularly suitable for the efficient and clean combustion of low-quality coal (such as low-volatile, high-ash coal) and pulverized coal with a wide particle size distribution (10-200μm), addresses the core defects of W-type boiler burners through an innovative "particle size sorting-directional distribution-staged combustion" design. It significantly improves ignition stability, combustion efficiency, and environmental performance, making it especially suitable for the combustion of low-quality coal and pulverized coal with a wide particle size distribution. This invention has high practical value and significant potential for wider application.

[0039] The core sorting principle of this invention lies in utilizing the centrifugal force field constructed by the burner inlet elbow to adapt to the inertial separation characteristics of the gas-solid two-phase flow of pulverized coal. Furthermore, the change in the flow channel cross-section and cross-guiding achieve particle size reorganization. A sorting cross-section CC is formed at the outlet of the burner inlet elbow. The dense-phase coarse powder region on the outer wall of the inlet elbow is defined as the coarse powder inlet channel M1, and the fine powder region on the inner side and center of the inlet elbow is defined as the fine powder inlet channel N1. A reorganization cross-section DD is formed at the burner nozzle. The central injection area is defined as the coarse powder outlet channel M2, and the outer annular area is defined as the fine powder outlet channel N2. When the airflow carrying pulverized coal with a wide particle size distribution flows through the inlet elbow, the larger coarse particles are thrown towards the outer arc side wall of the inlet elbow due to their greater inertia, forming a dense-phase coarse powder layer; the smaller fine particles adhere to the center of the elbow with the airflow, forming a fine powder flow. Subsequently, the stratified airflow is physically cut and reorganized using a cross-sorting and guiding assembly: the guide plate 7, deflecting "from the outside in," guides the coarse powder layer in region M1 into the central region M2, where it is rectified by the coarse pulverized coal triangular guide plate 10 and accelerated by the fine pulverized coal conical guide plate 5, forming a high-momentum jet; the guide plate 11, deflecting "from the inside out," guides and diverts the fine powder layer in region N1 to the peripheral region N2. Finally, a distribution of "concentrated injection of coarse powder in the inner layer - coating of fine powder in the outer layer" is formed at the outlet section.

[0040] This invention cleverly utilizes the inherent centrifugal segregation phenomenon of elbows to achieve efficient coal powder classification through a simple static flow guiding structure. It has a simple structure, no moving parts, low flow resistance and wear resistance, and is particularly suitable for power plant boilers that burn low-quality coal (low volatile matter, high ash content) and coal powder with a wide particle size distribution.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, any improvements made without departing from the principle of the present invention, including combinations with the above specific embodiments, are within the protection scope of the present invention.

Claims

1. A W-type boiler burner based on pulverized coal particle size sorting, characterized in that: The burner includes a burner housing (3), one end of which is provided with an inlet section, and inside the burner housing are a sorting and recombining section and a nozzle section arranged in a vertical direction; the inlet section, the sorting and recombining section and the nozzle section are connected in sequence; the inlet section includes a horizontally arranged inlet straight pipe section (1) and an inlet elbow (2) that is connected to it at a downward 90 degrees; the sorting and recombining section includes an inner ring channel cylinder (6) located inside the burner housing (3), and the inner ring channel cylinder (6) is coaxially suspended with the vertical section of the burner housing (3); the inner ring channel cylinder (6) divides the internal flow channel of the burner radially into an annular area of ​​an outer ring channel (8) and an inner ring channel (9) that are not interconnected; the outer wall of the inlet elbow (2) is a coarse powder inlet channel (M1), and the nozzle section The central injection zone is the coarse powder outlet channel (M2); the inner side and center of the inlet elbow (2) is the fine powder inlet channel (N1), and the outer annular area is the fine powder outlet channel (N2); the connection transition area between the inlet elbow (2) and the inner ring channel cylinder (6) is provided with a cross-sorting guide assembly, which includes a guide plate one (7) for deflection from the outside to the inside and a guide plate two (11) for deflection from the inside to the outside; one end of the guide plate one (7) is connected to the inner wall of the burner shell (3), and the other end is inserted into the inlet of the inner ring channel (9) at an inward angle; one end of the guide plate two (11) is connected to the bottom inlet edge of the inner ring channel cylinder (6), and the other end extends outward at an inward angle to the inner arc side flow channel of the inlet elbow (2).

2. A W-type boiler burner based on pulverized coal particle size sorting according to claim 1, characterized in that: The radial width of the coarse powder inlet channel (M1) is 0.15-0.3 times the diameter of the inlet straight pipe section (1); the equivalent diameter of the fine coal powder inlet channel (N1) is 0.4-0.7 times the diameter of the inlet straight pipe section (1); the diameter of the coarse powder outlet channel (M2) is 0.35-0.55 times the diameter of the inlet straight pipe section (1); and the radial width of the fine powder outlet channel (N2) is 0.1-0.25 times the diameter of the inlet straight pipe section.

3. A W-type boiler burner based on pulverized coal particle size sorting according to claim 1, characterized in that: The inner ring channel (9) is provided with a coarse coal powder triangular guide plate (10) at its internal entrance. The coarse coal powder triangular guide plate (10) has a wedge-shaped or triangular cone structure in cross section, and the tip of the coarse coal powder triangular guide plate (10) faces the direction of the coarse coal powder flow.

4. A W-type boiler burner based on pulverized coal particle size sorting according to claim 3, characterized in that: The inner ring channel is provided with a fine coal powder conical guide plate (5). The fine coal powder conical guide plate (5) is located on the central axis of the inner ring channel cylinder (6) and is located in the fine powder inlet channel area. Its cross-section is a streamlined spindle or cone structure.

5. A W-type boiler burner based on pulverized coal particle size sorting according to claim 1, characterized in that: The nozzle section outlet is a contraction structure (4), which is matched with the outlet end of the inner ring channel cylinder (6) to form a contraction nozzle.

6. A W-type boiler burner based on pulverized coal particle size sorting according to claim 1, characterized in that: The guide plate (7) is tangent to the outer streamline of the inlet elbow (2) and inclined inward at an angle of 20-45°.

7. A W-type boiler burner based on pulverized coal particle size sorting according to claim 1, characterized in that: The guide plate 2 (11) is tangent to the inner streamline of the inlet elbow (2) and tilts outward at an angle of 20-45°.

8. A W-type boiler burner based on pulverized coal particle size sorting according to claim 4, characterized in that: The burner shell (3), inner ring channel cylinder (6), fine coal powder conical guide plate (5), coarse coal powder triangular guide plate (10), guide plate one (7) and guide plate two (11) are all made of high temperature resistant alloy steel and are coated with wear-resistant ceramic coating on the coal powder scouring surface.

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