Coal-fired boiler concave cavity vortex flow coal burner

Abstract

The application discloses a concave cavity standing vortex swirl coal powder burner of a coal-fired boiler, which comprises a burner outer shell body, a burner inner shell body is arranged in the burner outer shell body, four wind channel three-stage cyclones are arranged in the burner inner shell body, the four wind channel three-stage cyclones sequentially comprise a three-stage inner secondary air swirl channel, a two-stage primary air and coal powder straight flow channel, a one-stage inner secondary air swirl channel and a central air straight flow channel from outside to inside, and an outer secondary air channel is formed between the burner outer shell body and the burner inner shell body; the burner inner shell body is provided with an annular concave cavity wall surface at the position of the four wind channel three-stage cyclone outlet, a concave cavity standing vortex backflow area is formed, and a flame stably exists in the concave cavity standing vortex backflow area in a hot state. The burner can achieve the purpose of enhancing the anti-combustion oscillation and stable combustion capacity of the burner, and improves the safety and economy of the operation of a thermal power plant.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired boiler burners and relates to a concave cavity vortex pulverized coal burner for coal-fired boilers. Background Technology

[0002] Pulverized coal burners are crucial equipment in coal-fired power plant boiler systems, responsible for organizing the combustion of pulverized coal and converting its chemical energy into internal energy. The design and combustion organization of coal-fired boiler burners significantly impact the boiler's output steam parameters and the unit's power generation capacity. The requirements for pulverized coal burners in coal-fired power units include: rational combustion organization to ensure the flame fills the furnace; uniform outlet temperature with no significant high-temperature concentration zones within the furnace; and stable and reliable combustion without partial burner flameout.

[0003] Publication No. CN102506424A discloses a center-feed swirl pulverized coal burner with a stepped nozzle. The burner includes a nozzle, a primary air duct, an inner swirler, an inner secondary air duct, an outer swirler, an outer secondary air duct, and one or more conical pulverized coal separators. The nozzle includes an outer secondary air nozzle, an inner secondary air nozzle, and a primary air nozzle. The primary air duct, inner secondary air duct, and outer secondary air duct are sequentially nested together from the inside out. The secondary air ducts are coaxially arranged, and one or more conical pulverized coal separators are installed in the primary air duct. The outlets of the conical pulverized coal separators face the furnace, and the outlet diameters of the multiple conical pulverized coal separators gradually decrease from the inlet end of the primary air duct towards the furnace. An inner cyclone separator is installed in the inner secondary air duct, and an outer cyclone separator is installed in the outer secondary air duct. A primary air nozzle is fixedly connected to the outlet end of the primary air duct, an inner secondary air nozzle is fixedly connected to the outlet end of the inner secondary air duct, and an outer secondary air nozzle is fixedly connected to the outlet end of the outer secondary air duct. The lengths of the primary air nozzles are set as L3, the inner secondary air nozzles as L2, and the outer secondary air nozzles as L1. The positional relationship between the outer secondary air nozzles, the inner secondary air nozzles, and the primary air nozzles is any one of the following three positional relationships: When the lengths of the primary air nozzles L3, L2, and L1 increase sequentially, the burner nozzles are arranged in a trapezoidal shape, thus achieving optimal performance in the primary air ducts. A premixing section is formed between the internal secondary air and the primary air; or, when the internal secondary air nozzle is flush with the primary air nozzle, and the external secondary air nozzle is set in a stepped manner from near to far from the furnace, a mixing section is formed between the internal and external secondary air; or, when the internal and external secondary air nozzles are flush with each other, and the external secondary air nozzle is set in a stepped manner from near to far from the furnace, a mixing section is formed between the primary air and the internal secondary air. Because of the premixing section, the internal secondary air and primary air are premixed in the burner before entering the furnace, which helps to form a stable central recirculation zone, prolongs the residence time of pulverized coal in the recirculation zone, and forms a suitable central recirculation zone, which is beneficial to the stable combustion of pulverized coal and effectively suppresses NOx formation. This invention can be widely applied to power plant boilers, and the pulverized coal burner has low NOx emissions and a wide range of coal types it can adapt to.

[0004] However, swirl-type opposed-flow coal-fired boilers are widely used in supercritical and ultra-supercritical thermal power units due to their excellent flame and high-temperature zone distribution. Because the burner flames are opposed, a single burner malfunctioning and shutting down can simultaneously negatively impact adjacent and opposite burners, causing significant combustion oscillations within the furnace. This increases the likelihood of triggering unit shutdown protection conditions compared to tangential-type coal-fired boilers. Therefore, improving the design of swirl-type pulverized coal burners in coal-fired boilers to enhance their resistance to combustion oscillations and stable combustion capabilities, thereby minimizing burner shutdowns and unit shutdowns caused by non-human factors, is of significant engineering importance for improving the operational safety and economy of thermal power plants. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a concave vortex pulverized coal burner for coal-fired boilers. This burner can enhance the burner's resistance to combustion oscillation and stabilize combustion, thereby improving the safety and economy of thermal power plant operation.

[0006] To achieve the above objectives, the present invention discloses a concave cavity vortex pulverized coal burner for a coal-fired boiler, comprising a burner outer shell, an inner burner shell, and a four-channel three-stage vortex generator arranged within the inner burner shell. The four-channel three-stage vortex generator, from the outside to the inside, includes a three-stage inner secondary air vortex channel, a two-stage primary air and pulverized coal direct flow channel, a one-stage inner secondary air vortex channel, and a central air direct flow channel. An outer secondary air channel is formed between the burner outer shell and the burner inner shell. The inner shell of the burner has an annular concave cavity wall at the outlet of the three-stage cyclone separator in the four-channel air duct, forming a concave vortex recirculation zone. When hot, the flame exists stably in the concave vortex recirculation zone.

[0007] Furthermore, the primary internal secondary air swirl channel is equipped with several primary swirl blades, and the primary internal secondary air swirl channel is connected to the internal secondary air, with the swirl direction being clockwise.

[0008] Furthermore, columnar wave-shaped flame-stabilizing teeth are installed in the secondary primary air and pulverized coal DC channel.

[0009] Furthermore, the inner secondary wind swirl channel is equipped with several third-stage swirl blades. The inner secondary wind swirl channel is circulated with inner secondary wind, and the swirl direction is counterclockwise.

[0010] Furthermore, the burner inner shell includes a head cavity vortex section and a tail-end progressively expanding flow stabilizing section.

[0011] Furthermore, air film cooling holes are provided on the vortex section of the head cavity.

[0012] Furthermore, mixing holes are provided on the gradually expanding and stabilizing flow section at the tail end.

[0013] Furthermore, after the primary air and pulverized coal pass through the columnar wave-shaped flame stabilizing teeth, turbulent vortices are generated. These turbulent vortices are then cut by the first-stage and third-stage vortices with opposite rotation directions, ensuring that the pulverized coal and airflow are fully mixed.

[0014] Furthermore, the flow rate ratio of the internal and external secondary air is adjusted by controlling the opening position of the pre-valve.

[0015] Furthermore, the external secondary air adjusts the temperature and supplements combustion at the tail end of the burner through mixing holes, resulting in a uniform temperature distribution at the burner outlet.

[0016] The present invention has the following beneficial effects: In specific operation, the concave cavity vortex pulverized coal burner for coal-fired boilers described in this invention has an annular concave cavity wall at the outlet of the three-stage cyclone separator in the four-channel air duct, forming a concave cavity vortex recirculation zone. In the hot state, the flame exists stably in the concave cavity vortex recirculation zone, effectively improving the burner's ability to resist combustion oscillation and stabilize combustion, greatly reducing the adverse effects of a single burner malfunctioning and shutting down on adjacent and relative burners, reducing the risk of coal-fired boiler shutdown, and improving the operational safety and economy of thermal power plants. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a front view of the present invention; Figure 2 This is an external schematic diagram of the present invention; Figure 3 This is a cross-sectional view of the present invention.

[0019] Among them, 1 is the central air direct flow channel; 2 is the first-stage internal secondary air swirl channel; 3 is the second-stage primary air and pulverized coal direct flow channel; 4 is the third-stage internal secondary air swirl channel; 5 is the external secondary air channel; 6 is the first-stage swirl blade; 7 is the cylindrical wave-shaped flame stabilizing tooth; 8 is the third-stage swirl blade; 9 is the burner outer shell; 10 is the burner inner shell; 11 is the concave cavity vortex recirculation zone; 12 is the gas film cooling hole; and 13 is the mixing hole. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0023] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0024] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0025] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] refer to Figure 1 and Figure 2 The coal-fired boiler concave vortex pulverized coal burner of the present invention includes a burner outer shell 9, and a burner inner shell 10 is provided inside the burner outer shell 9. The burner inner shell 10 is provided with a four-channel three-stage vortex generator. The four-channel three-stage vortex generator is provided with a three-stage inner secondary air vortex channel 4, a two-stage primary air and pulverized coal direct flow channel 3, a one-stage inner secondary air vortex channel 2, and a central air direct flow channel 1 in sequence from the outside to the inside. An outer secondary air channel 5 is formed between the burner outer shell 9 and the burner inner shell 10.

[0029] The burner inner shell 10 includes a head concave vortex section and a tail-stage progressively expanding flow stabilizing section.

[0030] The central air DC channel 1 is supplied with heated primary air.

[0031] The first-stage internal secondary air swirl channel 2 is equipped with several first-stage swirl blades 6. The first-stage internal secondary air swirl channel 2 is vented with internal secondary air, and the swirl direction is clockwise.

[0032] The secondary primary air and pulverized coal DC channel 3 is connected to the primary air and pulverized coal from the coal feeder. The secondary primary air and pulverized coal DC channel 3 is equipped with a columnar wave-shaped flame stabilizing tooth 7.

[0033] The third-stage internal secondary air swirl channel 4 is equipped with several third-stage swirl blades 8. The third-stage internal secondary air swirl channel 4 is for internal secondary air, and the swirl direction is counterclockwise.

[0034] An external secondary air passage 5 is formed between the inner shell 10 and the outer shell 9 of the burner. The flow ratio of the internal and external secondary air is adjusted by controlling the opening position of the pre-valve.

[0035] refer to Figure 3 The head concave vortex section of the burner inner shell 10 forms an annular concave cavity wall area at the outlet of the four-channel three-stage cyclone separator. The annular concave cavity wall area generates vortex backflow, which plays a role in stabilizing the flame and resisting combustion oscillation. The head concave vortex section of the burner inner shell 10 is provided with film cooling holes 12. The external secondary air enters the concave cavity through the film cooling holes 12, which plays a role in protecting the concave cavity wall. After the head concave vortex section of the burner inner shell 10, there is a tail-end progressively expanding stabilizing section. A relatively uniform outlet temperature distribution is obtained through progressive expansion. The tail-end progressively expanding stabilizing section of the burner inner shell 10 is provided with mixing holes 13. The external secondary air enters the burner inner shell 10 through the mixing holes 13, which plays a role in regulating the outlet temperature and supplementing combustion.

[0036] The working process of this invention is as follows: The flow ratio of internal and external secondary air is adjusted by the opening position of the pre-valve. The internal secondary air enters the burner through the primary internal secondary air swirl channel 2 and the tertiary internal secondary air swirl channel 4, with the swirl directions of the two being opposite. The external secondary air enters the external secondary air channel 5, which is composed of the burner outer shell 9 and the burner inner shell 10. The primary air from the coal feeder and pulverized coal enter the burner through the secondary primary air and pulverized coal direct flow channel 3. The secondary primary air and pulverized coal direct flow channel 3 is equipped with columnar wave-shaped flame stabilizing teeth 7. After passing through the columnar wave-shaped flame stabilizing teeth 7, the primary air and pulverized coal generate turbulent vortices. The turbulent vortices are cut by the primary and tertiary swirls with opposite directions, so that the pulverized coal and airflow are fully mixed, which is conducive to efficient combustion. The central air direct flow channel 1 carries a certain flow of hot primary air, which can delay the position of the flame root and effectively prevent backfire.

[0037] The burner inner shell 10 has an annular concave cavity wall at the outlet of the four-channel three-stage cyclone separator, forming a concave vortex recirculation zone 11. In the hot state, the flame exists stably in the concave vortex recirculation zone 11, effectively improving the burner's ability to resist combustion oscillation and stabilize combustion. Gas film cooling holes 12 are distributed on the concave cavity wall. The external secondary air enters the concave vortex recirculation zone 11 through the gas film cooling holes 12 to form a wall cooling gas film to protect the wall of the concave cavity. After the head concave vortex section of the burner inner shell 10, there is a tail-stage progressively expanding stabilizing section, which is distributed with mixing holes 13. The external secondary air adjusts the temperature and supplements combustion at the tail of the burner through the mixing holes 13, achieving a uniform temperature distribution at the burner outlet.

[0038] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0039] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0040] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A concave cavity vortex pulverized coal burner for a coal-fired boiler, characterized in that, The device includes a burner outer shell (9), and a burner inner shell (10) is provided inside the burner outer shell (9). The burner inner shell (10) is provided with a four-channel three-stage cyclone separator. The four-channel three-stage cyclone separator includes, from the outside to the inside, a three-stage inner secondary air cyclone channel (4), a two-stage primary air and pulverized coal direct current channel (3), a one-stage inner secondary air cyclone channel (2), and a central air direct current channel (1). An outer secondary air channel (5) is formed between the burner outer shell (9) and the burner inner shell (10). The inner shell of the burner (10) has an annular concave cavity wall at the outlet of the three-stage cyclone separator in the four-channel system, forming a concave vortex recirculation zone (11). When hot, the flame exists stably in the concave vortex recirculation zone (11).

2. The coal-fired boiler concave vortex pulverized coal burner according to claim 1, characterized in that, The first-stage internal secondary air vortex channel (2) is equipped with several first-stage vortex blades (6). The first-stage internal secondary air vortex channel (2) is vented with internal secondary air, and the vortex direction is clockwise.

3. The coal-fired boiler concave vortex pulverized coal burner according to claim 1, characterized in that, The secondary primary air and pulverized coal DC channel (3) is equipped with columnar wave-shaped flame stabilizing teeth (7).

4. The coal-fired boiler concave vortex pulverized coal burner according to claim 1, characterized in that, The three-stage internal secondary wind swirl channel (4) is equipped with several three-stage swirl blades (8). The three-stage internal secondary wind swirl channel (4) is vented with internal secondary wind, and the swirl direction is counterclockwise.

5. The coal-fired boiler concave vortex pulverized coal burner according to claim 1, characterized in that, The burner inner shell (10) includes a head cavity vortex section and a tail-end progressively expanding stabilizing section.

6. The coal-fired boiler concave vortex pulverized coal burner according to claim 5, characterized in that, A film cooling hole (12) is provided on the vortex section of the head cavity.

7. The coal-fired boiler concave vortex pulverized coal burner according to claim 5, characterized in that, Mixing holes (13) are provided on the gradually expanding and stabilizing flow section at the tail end.

8. The coal-fired boiler concave vortex pulverized coal burner according to claim 7, characterized in that, After the primary air and coal powder pass through the columnar wave-shaped flame stabilizer tooth (7), turbulent vortices are generated. The turbulent vortices are cut by the first-stage and third-stage vortices with opposite rotation directions, so that the coal powder and airflow are fully mixed after mixing.

9. The coal-fired boiler concave vortex pulverized coal burner according to claim 8, characterized in that, The flow rate ratio of internal and external secondary air is adjusted by controlling the opening position of the pre-valve.

10. The coal-fired boiler concave vortex pulverized coal burner according to claim 7, characterized in that, The external secondary air adjusts the temperature and supplements combustion at the tail of the burner through the mixing hole (13), and obtains a uniform temperature distribution at the burner outlet.

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