Cooperative combustion device and combustion method
The synergistic combustion device of external concentrator and self-stable combustion burner solves the problems of stable combustion and NOx emissions in tangential (or octagonal) pulverized coal boilers under low load, achieving stable operation at 15%-20% rated load and burnout effect at high load.
Patent Information
- Application Number
- CN202512054948.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-02-10
AI Technical Summary
Existing pulverized coal boilers with tangential (or octagonal) shapes are difficult to operate stably at 15%-20% of rated load, and have excessive NOx emissions and low burnout rates, failing to meet the requirements for deep peak shaving.
The system employs a combined combustion device of a DC burner and a swirl burner with external concentrators. Multiple external concentrators are connected to the DC pulverized coal burner and the self-stable combustion burner to form a pulverized coal airflow with varying concentrations, achieving staged combustion. The system adjusts the air velocity and pulverized coal concentration to achieve stable combustion and reduce NOx emissions.
It achieves stable operation of pulverized coal combustion at 15%-20% of rated load, reduces NOx emissions, and improves burnout efficiency at high loads.
Smart Images
Figure CN121498046A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of combustion technology for tangential boilers, and more particularly to a synergistic combustion device and combustion method. Background Technology
[0002] Coal-fired boiler power generation is currently the mainstay of my country's energy structure. The combustion method of coal-fired boilers primarily employs direct-flow burners arranged at the four or eight corners of the boiler furnace. Pulverized coal gas flow and secondary air are injected into the furnace through the direct-flow burner jets, converging in a tangential circular pattern. The side of the pulverized coal gas flow facing the fire is ignited by the direct impact of the high-temperature flame at the upstream adjacent corner. The four (or eight) corner jets support each other, forming a rotating combustion flame. The four-corner (or eight) tangential pulverized coal combustion boiler is the most widely used and mature boiler type in my country's power plants, accounting for approximately 70% or more of the total installed capacity. However, domestic coal-fired power units can only achieve 30%-40% of the rated load for stable combustion without oil injection. Relying solely on pulverized coal combustion is insufficient to achieve a 20%-30% rated load stable combustion effect, and the four-corner (or eight) tangential pulverized coal boiler cannot meet the requirements for deep peak shaving.
[0003] Currently, to achieve 20%-30% stable combustion load in boilers without oil injection, plasma, micro-oil, or medium-frequency electric heating technologies are needed to assist combustion stabilization and maintain long-term operation at 20%-30% of the rated load. Micro-oil combustion stabilization technology uses a small amount of oil (oil gun output 0.4t / h-0.6t / h) to ignite pulverized coal, enhancing ignition and stable combustion through its own combustion heat release. It has the advantage of strong coal adaptability, suitable for boilers from lignite to anthracite. However, its long-term operation has a certain negative impact on electrostatic precipitator electrodes and desulfurization slurry. Furthermore, using oil guns for stable combustion can consume tens of thousands of tons of oil annually, resulting in poor economic efficiency and extremely high costs. Plasma combustion stabilization technology mainly uses a high-power plasma gun to generate a high-temperature electric arc, enhancing ignition and stable combustion of pulverized coal. It is economical and environmentally friendly, but suffers from a short cathode lifespan and poor coal adaptability, and is often used in boilers burning bituminous coal with high volatile matter content. Medium-frequency electric heating technology uses medium-frequency induction heating to achieve good combustion stability under low and variable loads. However, the addition of an extra pulverizing system increases system complexity and investment costs; at the same time, medium-frequency induction is required to heat flammable bituminous coal, and long-term operation can easily lead to slagging in the flame extension tube.
[0004] Although there are currently corresponding co-combustion devices for direct-flow burners and swirl burners, which involve installing a self-sustaining combustion burner under direct-flow primary air, and co-combusting the original direct-flow burner and the self-sustaining combustion burner to achieve stable operation of a four-corner (or octagonal) tangential boiler relying solely on pulverized coal combustion at 20%-30% of rated load, while improving burnout efficiency at high loads, practical applications have shown that after applying this device, the four-corner (or octagonal) tangential boiler cannot operate stably at 15%-20% of rated load. Furthermore, the co-combustion device for direct-flow burners and swirl burners exhibits NO₂ at low loads. X Increased emissions and low burnout rates are among the problems. Therefore, in order to completely solve the poor deep peak-shaving capacity of tangential (or octagonal) boilers, NO... X To address issues such as excessive emissions and slagging on water-cooled walls, and to further enhance the stable operation of a four-corner (or eight-corner) tangential boiler relying solely on pulverized coal combustion at 15%-20% of its rated load, this invention proposes a device and method for the coordinated combustion of a direct-flow burner and a swirl burner with an external concentrator. Summary of the Invention
[0005] The purpose of this invention is to address the aforementioned shortcomings by providing a synergistic combustion device and method that enables stable combustion of pulverized coal under 15%-20% rated load conditions, while also reducing NO₂ levels. X It reduces emissions while improving burnout efficiency under high loads.
[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a co-combustion device, characterized in that it comprises: A tangential pulverized coal combustion boiler is provided with a direct-current pulverized coal burner at each of its rounded corners, and the output end of each direct-current pulverized coal burner faces the center of the tangential pulverized coal combustion boiler. Multiple self-stable combustion burners are respectively installed at the bottom of the corresponding DC pulverized coal burners; Multiple external concentrators, each with a primary air-powder inlet at its input end, and each external concentrator with a light primary air-powder outlet and a concentrated primary air-powder outlet at its output end. Each of the DC pulverized coal burners is provided with a light primary air-coal duct at its input end, and the end of the light primary air-coal duct away from the corresponding DC pulverized coal burner is connected to the corresponding light primary air-coal outlet. Each of the self-service stabilizing burners is provided with a rich primary air-coal pipe at its input end, and the end of the rich primary air-coal pipe away from the corresponding self-service stabilizing burner is connected to the corresponding rich primary air-coal outlet. The self-sustaining combustion burner is equipped with a swirl internal secondary air channel, axial blades, and a combustion stabilization chamber.
[0007] Furthermore, a first flow regulating valve is provided at the rich primary air-coal duct, which is used to regulate the rich primary air velocity; a second flow regulating valve is provided at the dilute primary air-coal duct, which is used to regulate the dilute primary air velocity; the swirl-type internal secondary air channel is located at the input end of the self-sustaining combustion burner; and a third flow regulating valve is provided on the swirl-type internal secondary air channel, which is used to regulate the swirl-type internal secondary air velocity.
[0008] Furthermore, the primary air velocity in the concentrated primary air-powder duct ranges from 18 to 30 m / s, the primary air velocity in the dilute primary air-powder duct ranges from 16 to 28 m / s, and the secondary air velocity in the vortex ranges from 35 to 50 m / s.
[0009] Furthermore, the external concentrator is provided with a first-stage blade, a second-stage blade, and a third-stage blade in sequence along the primary air-powder flow direction. The first-stage blade, the second-stage blade, and the third-stage blade are all inclined toward the concentrated primary air-powder outlet and are all located at the output end of the primary air-powder inlet of the external concentrator.
[0010] Furthermore, the external concentrator is used to separate primary air pulverized coal into light primary air pulverized coal and concentrated primary air pulverized coal. The separation ratio of light to concentrated primary air pulverized coal is 8:2-6:4, and the separation ratio of concentrated to concentrated primary air volume is 7:3-6:4. After separation, the concentration of concentrated coal pulverized coal is 1.20-1.32 kg coal pulverized coal / kg air, and the concentration of light coal pulverized coal is 0.62-0.74 kg coal pulverized coal / kg air.
[0011] Furthermore, the input end of the self-regulating combustion burner is provided with a DC primary air channel connected thereto. The axial blades are disposed between the DC primary air channel and the swirl inner secondary air channel. The combustion stabilization chamber is disposed at the output end of the DC primary air channel. There are multiple axial blades arranged in a ring. One end of each axial blade is fixedly connected to the outer wall of the DC primary air channel, and the other end is fixedly connected to the inner wall of the swirl inner secondary air channel.
[0012] A co-combustion combustion method includes the following steps: S1: The primary air powder enters the external concentrator from the primary air powder inlet, and is sequentially guided and separated by the first stage blade, the second stage blade and the third stage blade to form light primary air powder and concentrated primary air powder; S2: The light primary air powder enters the DC pulverized coal burner through the light primary air powder outlet and light primary air powder pipeline, and the rich primary air powder enters the DC primary air channel of the self-stable combustion burner through the rich primary air powder outlet and rich primary air powder pipeline. The rich primary air velocity, light primary air velocity and secondary air velocity in the swirl are adjusted by the first flow regulating valve, the second flow regulating valve and the light primary air powder pipeline respectively, so that the primary air powder forms a stable reflux zone in the combustion stabilization chamber of the self-stable combustion burner. S3: Adjust the first flow regulating valve and the second flow regulating valve according to the boiler operating load to change the wind speed and coal powder concentration of the rich primary air and the light primary air, so as to realize the coordinated combustion of the DC coal pulverized burner and the self-stable combustion burner.
[0013] The beneficial effects of this invention are reflected in: In this invention, multiple external concentrators are connected to a DC pulverized coal burner and a self-contained combustion stabilizer burner, distributed at the rounded corners of a tangential pulverized coal combustion boiler. During operation, these concentrators create both concentrated and diluted pulverized coal flow patterns within the furnace. The high-concentration pulverized coal flow in the center rapidly ignites and burns within the combustion stabilizer chamber. The already ignited concentrated and diluted pulverized coal then mixes and ignites the diluted pulverized coal. Simultaneously, the flame from the self-contained combustion stabilizer burner ignites the diluted pulverized coal flame from the DC pulverized coal burner. This achieves staged combustion of pulverized coal, amplifying the combustion energy step by step. Consequently, coal-fired power units can achieve stable combustion at 15%-20% of rated load using only pulverized coal combustion, reducing NOx emissions. X It reduces emissions and can improve burnout performance under high loads. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram showing the setup of the DC pulverized coal burner and the self-sustaining combustion burner in this invention; Figure 3 This is a schematic diagram illustrating the tangential ignition principle of the present invention; Figure 4 This is a schematic diagram showing the arrangement of the DC pulverized coal burner and the self-sustaining combustion burner in this invention; Figure 5 This is a side view schematic diagram of the DC pulverized coal burner and the self-sustaining combustion burner in this invention; Figure 6 This is a schematic diagram of the morphology of the combustion stabilization chamber and the reflux zone inside the furnace in this invention.
[0015] In the picture: 1. External concentrator; 2. DC pulverized coal burner; 3. Self-sustaining combustion burner; 4. First-stage blades; 5. Second-stage blades; 6. Third-stage blades; 7. First flow regulating valve; 8. Second flow regulating valve; 9. Lean primary air-coal duct; 10. Rich primary air-coal duct; 11. Swirl internal secondary air passage; 12. Axial blades; 13. Combustion stabilization chamber; 14. Primary air-coal inlet; 15. Tangential pulverized coal combustion boiler; 16. Lean primary air-coal outlet; 17. Rich primary air-coal outlet; 18. DC primary air passage; 19. Third flow regulating valve. Detailed Implementation
[0016] 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 a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. 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.
[0017] Please see Figure 1-6 The present invention discloses a co-combustion device, including a tangential pulverized coal combustion boiler 15, which can be a four-cornered or octagonal tangential boiler. Each rounded corner of the tangential pulverized coal combustion boiler 15 is equipped with a DC pulverized coal burner 2. The output end of each DC pulverized coal burner 2 faces the center of the tangential pulverized coal combustion boiler 15, and a self-stable combustion burner 3 is installed at the bottom of each DC pulverized coal burner 2.
[0018] In one embodiment, the device further includes multiple external concentrators 1. Each external concentrator 1 has a primary air-coal inlet 14 at its input end and a light primary air-coal outlet 16 and a rich primary air-coal outlet 17 at its output end. Each DC pulverized coal burner 2 has an interconnected light primary air-coal pipe 9 at its input end, and the end of the light primary air-coal pipe 9 away from the corresponding DC pulverized coal burner 2 is connected to the corresponding light primary air-coal outlet 16. Each self-stable combustion burner 3 has an interconnected rich primary air-coal pipe 10 at its input end, and the end of the rich primary air-coal pipe 10 away from the corresponding self-stable combustion burner 3 is connected to the corresponding rich primary air-coal outlet 17. The self-stable combustion burner 3 is provided with a swirling internal secondary air channel 11, axial blades 12, and a combustion stabilization chamber 13.
[0019] In specific implementation, multiple external concentrators 1 are connected to the DC pulverized coal burner 2 and the self-contained combustion stabilizer burner 3, and they are distributed at the rounded corners of the tangential pulverized coal combustion boiler 15. During operation, they create concentrated and dilute pulverized coal airflows in the furnace. At this time, the high-concentration pulverized coal airflow in the center quickly ignites and burns in the combustion stabilizer chamber 13. Then, the already ignited concentrated and dilute pulverized coal mixes and ignites the dilute pulverized coal. Simultaneously, the flame formed by the self-contained combustion stabilizer burner 3 ignites the dilute pulverized coal flame of the DC pulverized coal burner 2, realizing staged combustion of pulverized coal and amplifying the combustion energy step by step. This allows the coal-fired power unit to achieve stable combustion at 15%-20% of rated load and reduce NO by relying solely on pulverized coal combustion. X It reduces emissions and can improve burnout performance under high loads.
[0020] In one embodiment, a first flow regulating valve 7 is installed at the rich primary air-coal duct 10 to regulate the rich primary air velocity, and a second flow regulating valve 8 is installed at the dilute primary air-coal duct 9 to regulate the dilute primary air velocity. The swirl-type internal secondary air channel 11 is located at the input end of the self-sustaining combustion burner 3, and a third flow regulating valve 19 is installed on the swirl-type internal secondary air channel 11 to regulate the swirl-type internal secondary air velocity.
[0021] In specific implementation, the first flow regulating valve 7 of the rich primary air-coal pulverized coal pipeline 10, the second flow regulating valve 8 of the lean primary air-coal pulverized coal pipeline 9, and the third flow regulating valve 19 of the swirl inner secondary air channel 11 adjust the corresponding air velocity to adapt to different loads of the tangential pulverized coal combustion boiler 15. By adjusting and optimizing the mixing and combustion of rich and lean pulverized coal, stable combustion and NO reduction can be achieved. X The effect of emissions and improved burnout rate.
[0022] In one embodiment, the primary air velocity in the primary air-powder duct 10 ranges from 18 to 30 m / s, the primary air velocity in the secondary air-powder duct 9 ranges from 16 to 28 m / s, and the secondary air velocity in the vortex ranges from 35 to 50 m / s.
[0023] In one embodiment, the external concentrator 1 is provided with a first-stage blade 4, a second-stage blade 5 and a third-stage blade 6 in sequence along the primary air-powder flow direction. The first-stage blade 4, the second-stage blade 5 and the third-stage blade 6 are all inclined toward the primary air-powder outlet 17 of the external concentrator and are all located at the output end of the primary air-powder inlet 14 of the external concentrator.
[0024] In practice, the primary air-coal mixture enters the external concentrator 1 through the sequential arrangement of the first-stage blade 4, the second-stage blade 5, and the third-stage blade 6. It is then guided by the aforementioned multiple inclined blades, thus achieving efficient concentration-lean separation and obtaining primary air-coal mixture with high concentration suitable for stable combustion and low concentration suitable for supplementary combustion.
[0025] In one embodiment, an external concentrator 1 is used to separate primary air pulverized coal into light primary air pulverized coal and concentrated primary air pulverized coal. The separation ratio of light to concentrated primary air pulverized coal is 8:2-6:4, and the separation ratio of concentrated to concentrated primary air volume is 7:3-6:4. After separation, the concentration of concentrated coal pulverized coal is 1.20-1.32 kg coal pulverized coal / kg air, and the concentration of light coal pulverized coal is 0.62-0.74 kg coal pulverized coal / kg air.
[0026] In one embodiment, the input end of the self-stable combustion burner 3 is provided with a DC primary air channel 18 connected thereto. Axial blades 12 are disposed between the DC primary air channel 18 and the swirl inner secondary air channel 11. The combustion stabilization chamber 13 is disposed at the output end of the DC primary air channel 18. There are multiple axial blades 12 arranged in a ring. One end of each axial blade 12 is fixedly connected to the outer wall of the DC primary air channel 18, and the other end is fixedly connected to the inner wall of the swirl inner secondary air channel 11.
[0027] In practice, the concentrated primary air powder enters the combustion stabilization chamber 13 directly through the DC primary air channel 18. The secondary air in the swirl is guided by the axial blades 12 in a ring to form a rotating airflow before entering the combustion stabilization chamber 13. The two interact in the combustion stabilization chamber 13 to form a stable high-temperature recirculation zone as a continuous ignition heat source, which solves the problems of easy flame extinguishing and poor ignition reliability under low load and achieves the effect of efficient and stable combustion.
[0028] Working principle: Primary air and pulverized coal enter the external concentrator 1 through the primary air and pulverized coal inlet 14. Under the sequential covering action of the first-stage blade 4, the second-stage blade 5, and the third-stage blade 6, the primary air and pulverized coal are divided into light and rich primary air and pulverized coal. The light primary air and pulverized coal flows into the light primary air and pulverized coal outlet 16, and then enters the direct-flow pulverized coal burner 2 through the light primary air and pulverized coal pipeline 9. The rich primary air and pulverized coal flows into the rich primary air and pulverized coal outlet 17, and then enters the direct-flow primary air channel 18 through the rich primary air and pulverized coal pipeline 10, and finally enters the self-sustaining combustion burner 3. The direct-flow primary air and pulverized coal enter the combustion chamber 13 in a direct-flow manner through the direct-flow primary air channel 18. The secondary air in the swirl enters the combustion chamber 13 in a rotating manner after passing through the axial blades 12 in the swirl secondary air channel 11. Under the action of the swirl secondary air and the combustion chamber 13, the primary air and pulverized coal form a stable reflux zone in the combustion chamber 13, and enter the furnace of the tangential pulverized coal combustion boiler 15 in the form of a reflux zone.
[0029] When the boiler is operating at a high load exceeding 50% of its rated load, the opening of the second flow regulating valve 8 is changed to 80%-100%, controlling the primary air velocity entering the DC pulverized coal burner 2 through the light primary air-coal duct 9 to 26-30 m / s, with a light pulverized coal concentration of 0.70-0.74 kg pulverized coal / kg air. The opening of the first flow regulating valve 7 is changed to 80%-100%, controlling the primary air velocity entering the DC primary air channel 18 through the rich primary air-coal duct 10 to 24-28 m / s, with a rich pulverized coal concentration of 1.28-1.32 kg pulverized coal / kg air. Then, the third flow regulating valve 19 is shut off, so that there is no rotating secondary air inside the self-stable combustion burner 3.
[0030] When the boiler is operating at 40%-50% of its rated load, the primary air velocity entering the DC pulverized coal burner 2 through the light primary air-coal duct 9 is controlled to 22-26 m / s by changing the opening of the second flow regulating valve 8 to 60%-80%, with a light pulverized coal concentration of 0.66-0.70 kg pulverized coal / kg air. The primary air velocity entering the DC primary air channel 18 through the rich primary air-coal duct 10 is controlled to 20-24 m / s by changing the opening of the first flow regulating valve 7 to 60%-80%, with a rich pulverized coal concentration of 1.24-1.28 kg pulverized coal / kg air. The secondary air velocity entering the vortex inner secondary air channel 11 is controlled to 45-50 m / s by changing the opening of the third flow regulating valve 19 to 80%-100%.
[0031] When the boiler is operating at 30%-40% of its rated load, the primary air velocity entering the DC pulverized coal burner 2 through the light primary air-coal duct 9 is controlled to 20-22 m / s by changing the opening of the second flow regulating valve 8 to 50%-60%, with a light pulverized coal concentration of 0.64-0.66 kg pulverized coal / kg air. The primary air velocity entering the DC primary air channel 18 through the rich primary air-coal duct 10 is controlled to 18-20 m / s by changing the opening of the first flow regulating valve 7 to 50%-60%, with a rich pulverized coal concentration of 1.22-1.24 kg pulverized coal / kg air. The secondary air velocity entering the vortex inner secondary air channel 11 is controlled to 40-45 m / s by changing the opening of the third flow regulating valve 19 to 60%-80%.
[0032] When the boiler is operating at 20% of its rated load, by changing the opening of the second flow regulating valve 8 to 40%-50%, the primary air velocity entering the DC pulverized coal burner 2 through the light primary air-coal duct 9 is controlled to 18-20 m / s, and the light pulverized coal concentration is 0.62-0.64 kg pulverized coal / kg air. By changing the opening of the first flow regulating valve 7 to 40%-50%, the primary air velocity entering the DC primary air channel 18 through the rich primary air-coal duct 10 is controlled to 16-18 m / s, and the rich pulverized coal concentration is 1.20-1.22 kg pulverized coal / kg air. By changing the flow regulating valve 19 to 40%-60%, the secondary air velocity entering the vortex inner secondary air channel 11 is controlled to 35-40 m / s.
[0033] A co-combustion combustion method includes the following steps: S1: Primary air powder enters the external concentrator 1 from the primary air powder inlet 14, and is sequentially guided and separated by the first stage blade 4, the second stage blade 5 and the third stage blade 6 to form light primary air powder and concentrated primary air powder. S2: The light primary air powder enters the DC pulverized coal burner 2 through the light primary air powder outlet 16 and the light primary air powder pipeline 9, and the rich primary air powder enters the DC primary air channel 18 of the self-stable combustion burner 3 through the rich primary air powder outlet 17 and the rich primary air powder pipeline 10. The rich primary air velocity, light primary air velocity and secondary air velocity in the swirl are adjusted by the first flow regulating valve 7, the second flow regulating valve 8 and the light primary air powder pipeline 9 respectively, so that the primary air powder forms a stable reflux zone in the combustion stabilization chamber 13 of the self-stable combustion burner 3. S3: Adjust the first flow regulating valve 7 and the second flow regulating valve 8 according to the boiler operating load to change the wind speed and coal powder concentration of the rich primary air and the light primary air, so as to achieve coordinated combustion between the DC coal pulverizer 2 and the self-stable combustion burner 3.
[0034] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.
[0035] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0036] Additionally, "multiple" refers to two or more.
[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A co-combustion device, characterized in that, include: The tangential pulverized coal combustion boiler (15) has a DC pulverized coal burner (2) installed at each of its rounded corners, and the output end of each DC pulverized coal burner (2) is directed toward the center of the tangential pulverized coal combustion boiler (15). Multiple self-stable combustion burners (3) are respectively installed at the bottom of the corresponding DC pulverized coal burners (2); Multiple external concentrators (1) are provided with a primary air powder inlet (14) at their input end, and each of the external concentrators (1) is provided with a light primary air powder outlet (16) and a concentrated primary air powder outlet (17) at its output end. Each of the DC pulverized coal burners (2) is provided with a light primary air pulverized coal pipe (9) at its input end, and the end of the light primary air pulverized coal pipe (9) away from the corresponding DC pulverized coal burner (2) is connected to the corresponding light primary air pulverized coal outlet (16). Each of the self-stable combustion burners (3) is provided with a rich primary air-coal pipe (10) at its input end, and the end of the rich primary air-coal pipe (10) away from the corresponding self-stable combustion burner (3) is connected to the corresponding rich primary air-coal outlet (17). The self-stable combustion burner (3) is provided with a swirl internal secondary air channel (11), axial blades (12) and a combustion stabilization chamber (13).
2. The co-combustion device according to claim 1, characterized in that: A first flow regulating valve (7) is provided at the concentrated primary air-coal duct (10), which is used to regulate the concentrated primary air velocity. A second flow regulating valve (8) is provided at the dilute primary air-coal duct (9), which is used to regulate the dilute primary air velocity. The swirl-type internal secondary air channel (11) is located at the input end of the self-sustaining combustion burner (3). A third flow regulating valve (19) is provided on the swirl-type internal secondary air channel (11), which is used to regulate the swirl-type internal secondary air velocity.
3. The co-combustion device according to claim 2, characterized in that: The primary air velocity in the primary air-powder duct (10) ranges from 18 to 30 m / s, the primary air velocity in the secondary air-powder duct (9) ranges from 16 to 28 m / s, and the secondary air velocity in the vortex ranges from 35 to 50 m / s.
4. The co-combustion device according to claim 1, characterized in that: The external concentrator (1) has a first-stage blade (4), a second-stage blade (5) and a third-stage blade (6) arranged sequentially along the primary air-powder flow direction. The first-stage blade (4), the second-stage blade (5) and the third-stage blade (6) are all inclined toward the primary air-powder outlet (17) and are all located at the output end of the primary air-powder inlet (14) of the external concentrator.
5. The co-combustion device according to claim 1, characterized in that: The external concentrator (1) is used to separate primary air pulverized coal into light primary air pulverized coal and concentrated primary air pulverized coal. The separation ratio of the amount of concentrated and light primary air pulverized coal is 8:2-6:4, and the separation ratio of the amount of concentrated and light primary air pulverized coal is 7:3-6:
4. After separation, the concentration of concentrated coal pulverized coal is 1.20-1.32 kg coal pulverized coal / kg air, and the concentration of light coal pulverized coal is 0.62-0.74 kg coal pulverized coal / kg air.
6. The co-combustion device according to claim 1, characterized in that: The input end of the self-stable combustion burner (3) is provided with a DC primary air channel (18) connected to it. The number of axial blades (12) is multiple and they are arranged in a ring. One end of each axial blade (12) is fixedly connected to the outer wall of the DC primary air channel (18), and the other end is fixedly connected to the inner wall of the swirl inner secondary air channel (11).
7. A co-combustion combustion method, comprising the co-combustion device according to any one of claims 1-6, characterized in that, Includes the following steps: S1: The primary air powder enters the external concentrator (1) from the primary air powder inlet (14), and is sequentially guided and separated by the first stage blade (4), the second stage blade (5) and the third stage blade (6) to form light primary air powder and concentrated primary air powder; S2: The light primary air powder enters the DC pulverized coal burner (2) through the light primary air powder outlet (16) and the light primary air powder pipeline (9), and the rich primary air powder enters the DC primary air channel (18) of the self-stable combustion burner (3) through the rich primary air powder outlet (17) and the rich primary air powder pipeline (10). The rich primary air velocity, light primary air velocity and secondary air velocity in the swirl are adjusted by the first flow regulating valve (7), the second flow regulating valve (8) and the light primary air powder pipeline (9) respectively, so that the primary air powder forms a stable reflux zone in the combustion chamber (13) of the self-stable combustion burner (3); S3: Adjust the first flow regulating valve (7) and the second flow regulating valve (8) according to the boiler operating load to change the wind speed and coal powder concentration of the rich primary air and the light primary air and coal powder, so as to realize the coordinated combustion of the DC coal powder burner (2) and the self-stable combustion burner (3).