Four air duct three cyclone of burner for coal-fired boiler

Abstract

This invention discloses a four-channel, three-stage cyclone separator for a coal-fired boiler. The outer ring wall of the three-stage cyclone channel has a gradually expanding ring wall at its tail end. A central direct current channel is formed inside the ring wall of the central direct current channel. A primary secondary air cyclone channel is formed between the ring wall of the central direct current channel and the outer ring wall of the primary cyclone channel. A secondary pulverized coal and primary air direct current channel is formed between the outer ring wall of the primary cyclone channel and the outer ring wall of the secondary direct current channel. A tertiary secondary air cyclone channel is formed between the outer ring wall of the secondary direct current channel and the outer ring wall of the tertiary cyclone channel. Inlet-stage cylindrical corrugated teeth are evenly distributed circumferentially at the inlet position of the secondary pulverized coal and primary air direct current channel. Outlet-stage cylindrical corrugated teeth are evenly distributed circumferentially at the outlet position of the secondary pulverized coal and primary air direct current channel. This cyclone separator can improve combustion efficiency and enhance the uniformity of the burner outlet temperature.

Description

Technical Field

[0001] This invention belongs to the technical field of coal-fired boiler burners, and relates to a three-stage cyclone separator with four air ducts for coal-fired boilers. Background Technology

[0002] The pulverized coal burner is responsible for organizing the combustion of pulverized coal, converting the chemical energy of coal into internal energy, and is a crucial piece of equipment in coal-fired boiler power units. The design of the burner and the combustion organization method greatly affect the boiler output and stability. Power units require burners to have the following characteristics: rational combustion organization, with the flame filling the furnace; uniform outlet temperature, with no obvious high-temperature concentration zones inside the furnace; stable and reliable combustion, without partial burner flameout.

[0003] Publication No. CN217082542U discloses a swirl burner channel structure for a pulverized coal boiler. From the center outwards, the structure comprises a mounting channel, a central air annular channel, a primary air-pulverized coal annular channel, an inner secondary air annular channel, and an outer secondary air annular channel. The mounting channel houses the ignition device. The central air annular channel surrounds the mounting channel and contains a central air swirl generator. The primary air-pulverized coal annular channel, the inner secondary air annular channel, and the outer secondary air annular channel surround the central air annular channel. Blades are installed within both the inner and outer secondary air annular channels. In conventional designs, the primary air carries pulverized coal into the burner and simultaneously supplies the oxygen required for initial combustion. To ensure stable combustion, the primary air is hot. In this invention, the primary air serves only as the power source for carrying pulverized coal into the burner, significantly reducing the primary air volume. Furthermore, ambient temperature air can be used for the primary air, reducing the specifications and requirements of related components such as pipes and fans, thus decreasing equipment investment. The central air supply ensures the oxygen required for the initial combustion stage. The central air and pulverized coal enter the boiler furnace through different channels, allowing the central air to be sourced from preheated secondary air, reaching temperatures above 200℃, providing favorable conditions for stable pulverized coal combustion. The conical central air cyclone ensures thorough mixing of the central air with the pulverized coal at the burner outlet. The swirling action of the central air and inner secondary air creates a recirculation zone at the burner outlet center, entraining high-temperature flue gas from the furnace. Simultaneously, high-temperature flue gas is also entrained and heated from the surrounding airflow, continuously developing the combustion process until complete combustion. The air required for pulverized coal combustion is divided into central air, primary air, inner secondary air, and outer secondary air, entering the boiler furnace through the central air annular channel, primary air-pulverized coal annular channel, inner secondary air annular channel, and outer secondary air annular channel, respectively. This stratified and graded air delivery to the boiler furnace controls the NOx generation during pulverized coal combustion.

[0004] In the combustion organization methods of boilers in thermal power units, the swirl-opposed and tangential-circle types are currently the two most commonly used. Among them, the swirl-opposed type is widely used in supercritical and ultra-supercritical thermal power units due to its excellent flame and high-temperature zone distribution. For swirl pulverized coal burners with swirl generators, the swirl generator is responsible for generating air swirls and is the most important component. How to improve the swirl generator design, enhance the mixing of pulverized coal and air swirls, and ensure that the flame uniformly fills the furnace without excessive combustion oscillations is of significant engineering importance for improving the economic efficiency and safety of thermal power plant operation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a four-channel three-stage cyclone separator for coal-fired boilers, which can improve combustion efficiency and enhance the uniformity of burner outlet temperature.

[0006] To achieve the above objectives, this invention discloses a four-channel, three-stage cyclone combustor for a coal-fired boiler, comprising, from the inside out, a central direct current channel annular wall, a primary cyclone channel outer annular wall, a secondary direct current channel outer annular wall, and a tertiary cyclone channel outer annular wall. The tertiary cyclone channel outer annular wall has a gradually expanding annular wall at its tail. A central direct current channel is formed inside the central direct current channel annular wall. A primary secondary cyclone channel is formed between the central direct current channel annular wall and the primary cyclone channel outer annular wall. A secondary pulverized coal and primary air direct current channel is formed between the primary cyclone channel outer annular wall and the secondary direct current channel outer annular wall. A tertiary secondary cyclone channel is formed between the secondary direct current channel outer annular wall and the tertiary cyclone channel outer annular wall. The inlet of the secondary pulverized coal and primary air DC channel is circumferentially distributed with inlet-stage cylindrical corrugated teeth; the outlet of the secondary pulverized coal and primary air DC channel is circumferentially distributed with outlet-stage cylindrical corrugated teeth.

[0007] Furthermore, at the outlet of the primary and secondary wind swirl channel, there are primary swirl blades with a clockwise rotation direction.

[0008] Furthermore, the third-stage secondary wind swirl channel contains third-stage swirl blades with a counterclockwise rotation direction.

[0009] Furthermore, the inner secondary wind enters the gradually expanding annular wall in a clockwise swirling motion through the primary secondary wind swirl channel, under the action of the primary swirl blades with a clockwise rotation direction.

[0010] Furthermore, the outer secondary wind enters the gradually expanding annular wall in a counterclockwise swirling motion through the third-stage secondary wind swirling channel, under the action of the third-stage swirling blades with a counterclockwise rotation direction.

[0011] Furthermore, support rods connecting the inner and outer ring walls of the secondary pulverized coal and primary air DC channels are distributed at the outlet positions.

[0012] Furthermore, as the pulverized coal and primary air from the coal feeder flow through the secondary pulverized coal and primary air direct current channels and pass through the circumferentially distributed inlet-stage cylindrical wave-shaped teeth at the inlet of the secondary pulverized coal and primary air direct current channels, the mixing degree of pulverized coal and primary air is enhanced by turbulence.

[0013] Furthermore, when the pulverized coal and primary air mixture flows directly out of the outlet stage cylindrical wavelet tooth, due to the sudden expansion of the flow area, a horseshoe-shaped vortex cluster is generated in the gradually expanding annular wall region, which improves the turbulence intensity at the DC end and the uniformity of oxygen-coal mixing.

[0014] Furthermore, the primary vortex flowing out of the primary secondary air vortex channel has the opposite vortex direction to the tertiary vortex flowing out of the tertiary secondary air vortex channel, and it traps the coal powder and primary air mixture flowing through the secondary coal powder and primary air direct channel inside.

[0015] Furthermore, near the outlet of the gradually expanding annular wall, the pulverized coal mixture swirling flow forms a stable reflux zone within the flame tube due to the combined effect of the swirling flow and the sudden expansion of the flow area.

[0016] The present invention has the following beneficial effects: In specific operation, the four-channel three-stage cyclone separator for coal-fired boilers described in this invention has inlet-stage cylindrical corrugated teeth evenly distributed circumferentially at the inlet position of the secondary pulverized coal and primary air direct current channel; and outlet-stage cylindrical corrugated teeth evenly distributed circumferentially at the outlet position of the secondary pulverized coal and primary air direct current channel. When pulverized coal and primary air from the coal feeder flow through the secondary pulverized coal and primary air direct current channel, passing through the inlet-stage cylindrical corrugated teeth evenly distributed circumferentially at the inlet position of the secondary pulverized coal and primary air direct current channel, the turbulence enhances the mixing degree of pulverized coal and primary air, and the pulverized coal and primary air mixture flows directly out of the outlet-stage cylindrical corrugated teeth. When the wave-shaped teeth are used, the flow area expands suddenly, generating horseshoe-shaped vortex clusters in the gradually expanding annular wall region. This enhances the turbulence intensity at the DC end and the uniformity of oxygen-coal mixing. The cylindrical wave-shaped teeth evenly distributed around the inlet and outlet of the secondary DC channel generate turbulence to enhance the mixing of pulverized coal and primary air. Under the cutting and mixing action of the first and third stage swirling flows with opposite directions, a uniformly mixed pulverized coal-air swirling flow is obtained in the space of the gradually expanding annular wall. This effectively improves the boiler combustion efficiency and the uniformity of the burner outlet temperature, avoids local accumulation of pulverized coal that could lead to deflagration and backfire, and helps improve the economic efficiency and safety of thermal power plant operation. 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 1This is an overall structural diagram of the present invention; Figure 2 This is a 1 / 4 sectional view of the present invention; Figure 3 This is a front view of the present invention; Figure 4 This is an axial sectional view of the present invention.

[0019] Among them, 1 is the central direct current channel; 2 is the primary secondary air swirl channel; 3 is the secondary pulverized coal and primary air direct current channel; 4 is the tertiary secondary air swirl channel; 5 is the primary swirl blade; 6 is the tertiary swirl blade; 7 is the annular wall of the central direct current channel; 8 is the outer annular wall of the primary swirl channel; 9 is the outer annular wall of the secondary direct current channel; 10 is the outer annular wall of the tertiary swirl channel; 11 is the gradually expanding annular wall; 12 is the inlet stage cylindrical wavelet tooth; 13 is the outlet stage cylindrical wavelet tooth; and 14 is the support rod. 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 2The four-channel three-stage cyclone burner for coal-fired boilers of the present invention includes a central direct current channel annular wall 7, a primary cyclone channel outer annular wall 8, a secondary direct current channel outer annular wall 9, and a tertiary cyclone channel outer annular wall 10 distributed sequentially from the inside to the outside. A gradually expanding annular wall 11 is provided at the tail of the tertiary cyclone channel outer annular wall 10. A central air direct current channel 1 is formed inside the central direct current channel annular wall 7. A primary secondary air cyclone channel 2 is formed between the central direct current channel annular wall 7 and the primary cyclone channel outer annular wall 8. A secondary pulverized coal and primary air direct current channel 3 is formed between the primary cyclone channel outer annular wall 8 and the secondary direct current channel outer annular wall 9. A tertiary secondary air cyclone channel 4 is formed between the secondary direct current channel outer annular wall 9 and the tertiary cyclone channel outer annular wall 10.

[0029] Hot primary air is introduced into the central air DC channel 1. The position of the flame root at the outlet of the cyclone separator is adjusted by regulating the central air flow rate. Under heavy load conditions and rapid load increase conditions, the central air flow rate is increased to push the flame root away from the cyclone separator. When the unit fails and stops, the central air flow rate is quickly increased to extinguish the flame.

[0030] The inner secondary air passes through the primary secondary air swirl channel 2; at the outlet of the primary secondary air swirl channel 2, there are primary swirl blades 5 with a clockwise rotation direction. Under the action of the primary swirl blades 5, the inner secondary air enters the gradually expanding annular wall 11 in a clockwise swirling motion.

[0031] refer to Figure 3 The pulverized coal and primary air mixed from the coal feeder enter the secondary pulverized coal and primary air direct flow channel 3; the inlet of the secondary pulverized coal and primary air direct flow channel 3 is circumferentially distributed with inlet-stage cylindrical wave-shaped teeth 12, which mainly play the role of creating turbulence and enhancing the mixing degree of pulverized coal and primary air.

[0032] The outlet of the secondary pulverized coal and primary air DC channel 3 is circumferentially distributed with columnar wave-shaped teeth 13, which mainly serve to enhance the turbulence intensity at the DC end and the uniformity of oxygen-coal mixing; the outlet of the secondary pulverized coal and primary air DC channel 3 is also distributed with support rods 14 connecting the inner and outer ring walls of the channel.

[0033] The secondary air is divided into inner and outer layers by the pre-positioned secondary air volume distribution baffle. The outer layer of secondary air passes through the third-stage secondary air swirl channel 4. The third-stage secondary air swirl channel 4 is equipped with third-stage swirl blades 6 that rotate counterclockwise. Under the action of the third-stage swirl blades 6, the outer secondary air enters the gradually expanding annular wall 11 in a counterclockwise swirling motion.

[0034] After exiting the direct and swirling channels, the direct and swirling gases from each stage enter the gradually expanding annular wall 11 at the tail of the swirler. The direct flow of the secondary pulverized coal and primary air mixture is cut and mixed by the first and third stage swirling gases with opposite directions, resulting in a uniformly mixed pulverized coal mixture swirling gas within a relatively small spatial scale. The direction of the swirling gas is determined by the distribution method of the internal and external secondary air flow rates. After exiting the gradually expanding annular wall 11, the pulverized coal mixture gas forms a stable flame in the recirculation zone within the flame tube under the combined action of the swirling gas and the sudden expansion of the flow area. Adjusting the direct flow rate of the central air can control the position of the recirculation zone and the flame root.

[0035] The working process of this invention is as follows: refer to Figure 4 The secondary air is split into two layers, inner and outer, by the pre-positioned secondary air volume distribution baffle and enters the cyclone separator. The inner layer of secondary air enters the gradually expanding annular wall 11 in a clockwise direction through the primary secondary air cyclone channel 2 and under the action of the primary cyclone blades 5 with a clockwise rotation direction. The outer layer of secondary air enters the gradually expanding annular wall 11 in a counterclockwise direction through the tertiary secondary air cyclone channel 4 and under the action of the tertiary cyclone blades 6 with a counterclockwise rotation direction.

[0036] When the pulverized coal and primary air from the coal feeder flow through the secondary pulverized coal and primary air direct current channel 3 and pass through the circumferentially distributed inlet-stage cylindrical corrugated teeth 12 at the inlet of the secondary pulverized coal and primary air direct current channel 3, a certain turbulence effect is generated in the channel due to the limited flow area, which enhances the mixing degree of pulverized coal and primary air. When the pulverized coal and primary air mixture flows directly out of the outlet-stage cylindrical corrugated teeth 13, a strong horseshoe vortex cluster is generated in the region of the gradually expanding annular wall 11 due to the sudden expansion of the flow area, which improves the turbulence intensity at the end of the direct current and the uniformity of oxygen-coal mixing. The support rod 14 connects the outer annular wall 8 of the primary cyclone channel and the outer annular wall 9 of the secondary direct current channel, supporting the secondary pulverized coal and primary air direct current channel 3, ensuring the structural rigidity and thermal deformation coordination of each channel, and ensuring the long-term reliable operation of the cyclone components.

[0037] The primary swirling flow exiting the primary secondary air swirling channel 2 has the opposite swirling direction to the tertiary swirling flow exiting the tertiary secondary air swirling channel 4, and it traps the coal powder and primary air mixture flowing through the secondary coal powder and primary air direct flow channel 3 inside. Due to the opposite swirling direction, the primary and tertiary swirling flows will exert a strong shearing and mixing effect on the coal powder and primary air mixture as it gradually flows out of the gradually expanding annular wall 11. When it flows out of the gradually expanding annular wall 11, it will obtain a uniformly mixed coal powder mixture swirling flow. The swirling direction is determined by the distribution method of the secondary air flow rate of the inner and outer layers. Near the outlet position of the gradually expanding annular wall 11, the coal powder mixture swirling flow forms a stable reflux zone in the flame tube due to the combined effect of the swirling flow and the sudden expansion of the flow area. Adjusting the central air flow through the central air direct flow channel 1 controls the reflux zone and the position of the flame root. The central air is hot primary air. Under high load conditions and rapid load increase conditions, increasing the central air flow rate can push the flame root away from the swirler. When the unit fails and stops, quickly increasing the central air flow rate can extinguish the flame.

[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 three-stage cyclone separator with four air ducts for a coal-fired boiler, characterized in that, The system includes a central DC channel ring wall (7), a first-stage vortex channel outer ring wall (8), a second-stage DC channel outer ring wall (9), and a third-stage vortex channel outer ring wall (10) arranged sequentially from the inside to the outside. The third-stage vortex channel outer ring wall (10) is provided with a gradually expanding ring wall (11) at its tail. A central air DC channel (1) is formed inside the central DC channel ring wall (7). A first-stage secondary air vortex channel (2) is formed between the central DC channel ring wall (7) and the first-stage vortex channel outer ring wall (8). A second-stage pulverized coal and primary air DC channel (3) is formed between the first-stage vortex channel outer ring wall (8) and the second-stage DC channel outer ring wall (9). A third-stage secondary air vortex channel (4) is formed between the second-stage DC channel outer ring wall (9) and the third-stage vortex channel outer ring wall (10). The inlet of the secondary pulverized coal and primary air DC channel (3) is circumferentially distributed with inlet-stage columnar corrugated teeth (12); the outlet of the secondary pulverized coal and primary air DC channel (3) is circumferentially distributed with outlet-stage columnar corrugated teeth (13).

2. The four-channel, three-stage cyclone separator for coal-fired boilers according to claim 1, characterized in that, At the outlet of the primary secondary wind swirl channel (2), there are primary swirl blades (5) with a clockwise rotation direction.

3. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 2, characterized in that, The third-stage secondary wind vortex channel (4) contains third-stage vortex blades (6) with a counterclockwise rotation direction.

4. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 3, characterized in that, The inner secondary wind enters the gradually expanding annular wall (11) in a clockwise swirling motion through the primary secondary wind swirling channel (2) and under the action of the primary swirling blades (5) with a clockwise swirling direction.

5. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 3, characterized in that, The outer secondary wind passes through the third-stage secondary wind swirl channel (4) and enters the gradually expanding annular wall (11) in a counterclockwise swirling motion under the action of the third-stage swirl blades (6) with a counterclockwise swirling direction.

6. The four-duct, three-stage cyclone separator for a coal-fired boiler according to claim 1, characterized in that, Support rods (14) connecting the inner and outer ring walls of the secondary pulverized coal and primary air DC channel (3) are distributed at the outlet position.

7. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 1, characterized in that, When the pulverized coal and primary air from the coal feeder pass through the secondary pulverized coal and primary air direct channel (3), and flow through the circumferentially distributed inlet columnar wave-shaped teeth (12) at the inlet of the secondary pulverized coal and primary air direct channel (3), the mixing degree of pulverized coal and primary air is enhanced by turbulence.

8. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 1, characterized in that, When the pulverized coal and primary air mixed gas flows directly out of the outlet stage cylindrical wavelet tooth (13), due to the sudden expansion of the flow area, a horseshoe-shaped vortex cluster is generated in the region of the gradually expanding annular wall (11), which improves the turbulence intensity at the DC end and the uniformity of oxygen-coal mixing.

9. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 1, characterized in that, The primary vortex flowing out of the primary secondary air vortex channel (2) has the opposite vortex direction to the tertiary vortex flowing out of the tertiary secondary air vortex channel (4), and the coal powder flowing through the secondary coal powder and primary air direct current channel (3) is sandwiched inside.

10. The four-channel, three-stage cyclone separator for a coal-fired boiler according to claim 1, characterized in that, Near the outlet of the gradually expanding annular wall (11), the pulverized coal mixture swirling flow forms a stable reflux zone in the flame tube due to the combined effect of the swirling flow and the sudden expansion of the flow area.

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