An adjustable wind duct structure cyclone burner and method of use thereof

Abstract

The application discloses a swirl burner with an adjustable air pipe structure and a method for using the same, belongs to the technical field of burners and burner applications, and aims to solve the problems of burner slagging and burning loss caused by burning Zhundong coal and the problem that the low-load stable combustion and flexible peak regulation capability cannot reach 20-30%. The swirl burner comprises, from outside to inside, an outer secondary air passage, an inner secondary air passage and a primary air passage, tangential blades are arranged in the outer secondary air passage, an outer secondary air diffuser is arranged at the outlet of the outer secondary air passage, axial adjustable blades are arranged in the inner secondary air passage, an inner secondary air diffuser is arranged at the outlet of the inner secondary air passage, an adjustable passage is arranged between the inner secondary air passage and the primary air passage, an adjustable inner secondary air pipe and an adjustable primary air pipe are arranged at the outlet of the adjustable passage, and the application is used for overcoming the problems of burner slagging and burning loss caused by burning Zhundong coal and the problem that the low-load stable combustion and flexible peak regulation capability is insufficient.

Description

Technical Field

[0001] This invention belongs to the field of burner and burner application technology, specifically relating to a swirl burner with an adjustable duct structure and its usage method. Background Technology

[0002] Among the many coal-fired power units in thermal power plants, the opposed-flow pulverized coal boiler is one of the three main types of boilers. Its burner is a swirl pulverized coal burner, employing a front and rear wall opposed-flow combustion method. By creating a reflux zone at the burner outlet area that facilitates ignition, the high-temperature flue gas entrained in the reflux zone ignites the pulverized coal gas stream, ensuring timely ignition. Therefore, opposed-flow pulverized coal boilers are widely used in thermal power plants. The eastern part of the Junggar Basin in Xinjiang is rich in coal resources, among which the Zhundong Coalfield is currently the largest intact coalfield discovered in my country, with abundant reserves and large-scale use domestically. Zhundong coal is characterized by high volatile matter content (Vdaf>30%), low ignition point (400℃~460℃), low ash melting temperature (1080℃~1239℃), and large reserves. However, due to the ash melting temperature of Zhundong coal being 1080℃~1239℃, which is less than 1260℃, it is classified as a coal with a severe tendency to slagging. This can easily lead to severe slagging problems in burners during actual combustion. Furthermore, the low ignition point and easy ignition characteristics of Zhundong coal cause burners burning out easily, especially those equipped with a combustion stabilizing ring and a primary air vent. In actual operation, severe burn-out of the combustion stabilizing ring and the primary air vent has been observed.

[0003] In recent years, new energy power generation, represented by photovoltaic and wind power, has been characterized by randomness and instability, placing higher demands on the peak-shaving capacity of traditional thermal power units. This requires some boilers to achieve stable combustion at 20%–30% or even lower loads, or even frequent start-ups and shutdowns, to promote the clean and low-carbon transformation of the power industry and help achieve the national carbon peak and carbon neutrality goals on schedule. Currently, when using Zhundong coal, the minimum stable combustion load of offset swirl pulverized coal boilers can only reach 40% of the rated load, far below the peak-shaving requirement of stable combustion at 20%–30% or even lower loads.

[0004] To address the issues of burner slagging, burn-off, and insufficient flexible peak-shaving capacity under low load caused by burning Zhundong coal, this invention proposes a swirl burner device and method with an adjustable duct structure. Summary of the Invention

[0005] In order to solve the problems of burner slagging and burn-off caused by burning Zhundong coal, and the problem that the low-load stable combustion and flexible peak-shaving capacity cannot reach 20-30%, this invention proposes a swirl pulverized coal burner with adjustable recirculation zone morphology and its usage method.

[0006] A swirl burner with an adjustable duct structure, wherein the swirl burner comprises, from the outside to the inside, an outer secondary air duct, an inner secondary air duct, and a primary air duct. The outer secondary air duct is provided with tangential blades and an outer secondary air vent is installed at its outlet. The inner secondary air duct is provided with axially adjustable blades and an inner secondary air vent is installed at its outlet. An adjustable channel is provided between the inner secondary air duct and the primary air duct, and an adjustable inner secondary air duct and an adjustable primary air duct are provided at the outlet of the adjustable channel.

[0007] Furthermore, the adjustable primary air duct is sleeved on the inner tube in the adjustable channel, and N rows of No. 1 rollers are provided between the adjustable primary air duct and the inner tube in the adjustable channel, where N is a positive integer greater than 2. The adjustable primary air duct is slidably connected to the inner tube in the adjustable channel through the N rows of No. 1 rollers. A No. 1 pull rod is provided at the end of the adjustable primary air duct away from the outlet. The tail of the No. 1 pull rod passes through the rear end plate of the adjustable channel and extends to the outside of the swirl burner.

[0008] Furthermore, the adjustable inner secondary air duct is inserted into the outer pipe in the adjustable channel, and N rows of No. 2 rollers are provided between the adjustable inner secondary air duct and the outer pipe in the adjustable channel, where N is a positive integer greater than 2. The adjustable inner secondary air duct is slidably connected to the outer pipe in the adjustable channel through the N rows of No. 2 rollers. A No. 2 tie rod is provided at the end of the adjustable inner secondary air duct away from the outlet. The tail of the No. 2 tie rod passes through the rear end plate of the adjustable channel and extends to the outside of the swirl burner.

[0009] Furthermore, the inner tube in the adjustable channel is provided with a front limiter baffle and a rear limiter baffle that cooperate with the first roller;

[0010] Furthermore, the outer tube in the adjustable channel is provided with a second front limiter baffle and a second rear limiter baffle that cooperate with the second roller;

[0011] Furthermore, the inner diameter of the adjustable primary air duct outlet is R1, the position of the adjustable primary air duct when adjusted to the first front limiter baffle is 0, the maximum distance the adjustable primary air duct moves backward from the first front limiter baffle is L1, the inner diameter of the adjustable inner secondary air duct outlet is R2, the position of the adjustable inner secondary air duct when adjusted to the corresponding second front limiter baffle is 0, and the maximum distance the adjustable inner secondary air duct moves backward from the second front limiter baffle is L2;

[0012] A method for using a swirl burner with an adjustable duct structure, the specific steps of which are as follows:

[0013] First, install the swirl pulverized coal burner on the front and rear walls of the swirl pulverized coal boiler. The installation method adopted is opposed arrangement. An adjustable inner secondary air duct and an adjustable primary air duct are installed at the burner nozzle. The positions of the inner secondary air duct and the adjustable primary air duct are adjusted through a pull rod, and the outlet area of the adjustable channel is incorporated into the outlet area of the inner secondary air channel or the primary air channel, thereby adjusting the outlet air speeds of the inner secondary air and the primary air to achieve the purpose of adjusting the shape and size of the recirculation zone at the burner outlet;

[0014] The air speed range in the primary air channel is 22 - 25 m / s. When the boiler operates under the condition of 20 - 50% of the rated load, this condition is low-load operation. Through the adjustment of the first pull rod to adjust the position of the adjustable primary air duct, when the Vdaf of the coal used > 30%, L1 = 50 - 250 mm, and the outlet air speed of the primary air channel is reduced to 17 - 21 m / s; when 20 < Vdaf of the coal used ≤ 30%, L1 = 300 - 400 mm, and the outlet air speed of the primary air channel is reduced to 15 - 18 m / s;

[0015] The air speed range in the inner secondary air channel is 30 - 42 m / s. When the boiler operates under the condition of more than 50% of the rated load, this condition is high-load operation. Through the adjustment of the second pull rod to adjust the position of the adjustable inner secondary air duct, when the Vdaf of the coal used > 30%, L2 = 250 - 400 mm, and the outlet air speed of the inner secondary air channel is reduced to 20 - 30 m / s; when 20 < Vdaf of the coal used ≤ 30%, L2 = 50 - 250 mm, and the outlet air speed of the inner secondary air channel is reduced to 25 - 32 m / s;

[0016] When the boiler operates under low-load conditions, a relatively large central recirculation zone is required at the outlet of the swirl burner. The operation is as follows: By adjusting the first pull rod to adjust the position of the adjustable primary air duct, when the Vdaf of the coal used > 30%, L1 = 50 - 250 mm, and the outlet air speed of the primary air channel is reduced to 17 - 21 m / s; when 20 < Vdaf of the coal used ≤ 30%, L1 = 300 - 400 mm, and the outlet air speed of the primary air channel is reduced to 15 - 18 m / s. Through the above operations, reducing the outlet air speed of the primary air can form a relatively large and stable central recirculation zone at the outlet of the swirl burner. At this time, the distance between the starting position of the central recirculation zone and the burner outlet is 0.15 < a < 0.2d, the length is 1.5d < l < 1.8d, and the diameter is 0.5d < D1 < 0.8d, where d is the diameter of the outer secondary air flare;

[0017] When the boiler is operating under high-load conditions, an appropriate annular recirculation zone needs to be formed at the outlet of the tangential combustion burner. The operation is as follows: By adjusting the second pull rod, the position of the adjustable inner secondary air duct is adjusted. When the Vdaf of the coal being burned > 30%, L2 = 250 - 400 mm, and the outlet air velocity of the inner secondary air passage is reduced to 20 - 30 m / s; when 20 < Vdaf of the coal being burned ≤ 30%, L2 = 50 - 250 mm, and the outlet air velocity of the inner secondary air passage is reduced to 25 - 32 m / s. Through the above operations, the outlet air velocity of the inner secondary air is reduced, an appropriate annular recirculation zone is formed at the outlet of the tangential combustion burner, and the pulverized coal is entrained with high-temperature flue gas through the annular recirculation zone and ignited, and the combustion is maintained. The distance a between the starting position of the annular recirculation zone and the burner outlet > 0.1d, the length is 0.6d < l < 1.0d, and the diameter is 0.2d < D2 < 0.4d, where d is the diameter of the outer secondary air flare.

[0018] The beneficial effects of the present application compared with the prior art:

[0019] The tangential combustion burner with an adjustable air duct structure and the usage method provided by the present invention can flexibly adjust the shape and size of the recirculation zone at the burner outlet according to the boiler load, meeting the requirements of flexible peak shaving, achieving stable combustion at low loads, and avoiding burning damage and slagging of the burner nozzles at the same time.

[0020] The outlet duct area of ​​existing swirl burners is fixed, resulting in a fixed shape and size of the recirculation zone at the burner outlet. This fails to meet the requirements for flexible peak shaving and cannot simultaneously ensure stable combustion at low boiler loads while preventing burner nozzle burn-out and slagging problems when burning Zhundong coal. To prevent burner nozzle burn-out and slagging when burning Zhundong coal, a low secondary air velocity (20~30m / s) and a high primary air velocity (22~25m / s) are generally required to form an annular recirculation zone in the burner outlet area. The recirculation zone is relatively small (diameter 0.2d~0.3d, length 0.5d~0.7d). Under high load (75%~100% rated load), although the flue gas temperature in the furnace is very high, reaching 1200~1400℃, the amount of high-temperature flue gas entrained in the recirculation zone is small, which can ensure that the burner nozzle is not burned under high load operation. However, under low load (20%~30% rated load), the flue gas temperature in the furnace is 230~300℃ lower than that under full load, which cannot guarantee the timely ignition of pulverized coal and cannot meet the low-load stable combustion requirement of 20%~30% rated load. To ensure stable combustion at low loads (20%~30% of rated load), a high secondary air velocity (30~42m / s) and a low primary air velocity (15~21m / s) are generally required. The recirculation zone is a large central recirculation zone (diameter 0.7d~1.3d, length 1.7d~2.1d). The recirculation entrains a large amount of high-temperature flue gas, forming a large high-temperature central recirculation zone in the burner outlet area, which promptly ignites the pulverized coal and achieves stable combustion at low loads. However, at high loads (75%~100% of rated load), the furnace flue gas temperature is high, further increasing the temperature of the recirculation zone. This results in excessively high temperatures in the main combustion zone at high loads. The starting point of the recirculation zone is close to the burner nozzle (a<0.1d), causing premature pulverized coal combustion, which can easily lead to burner nozzle burnout and slagging problems.

[0021] The present invention provides an adjustable air duct structure. At high loads (75% - 100% rated load), the adjustable inner secondary air duct is moved backward, and the adjustable channel is incorporated into the area of the inner secondary air channel, increasing the area of the inner secondary air outlet. The outlet velocity of the inner secondary air drops to 20 - 32 m / s, forming an annular recirculation zone between the primary air at the burner outlet and the outlet of the inner secondary air, and pushing the recirculation zone away from the nozzle (0.1d < a). While ensuring stable combustion at high loads, it prevents the high-temperature recirculation zone from being too close to the burner nozzle and causing burnout. At low loads (20% - 30% rated load), the adjustable inner secondary air duct is reset to the most forward position, the adjustable primary air duct is moved backward, and the adjustable channel is incorporated into the area of the primary air channel, increasing the area of the primary air outlet. The outlet velocity of the primary air drops to 15 - 21 m / s, forming a relatively large central recirculation zone (diameter 0.7d - 1.3d, length 1.7d - 2.1d) in the burner outlet area. The amount of high-temperature flue gas entrained by the recirculation is large, which can promptly ignite the pulverized coal to meet the low-load stable combustion requirements at 20% - 30% rated load.

[0022] The present invention provides a swirl burner device and method with an adjustable air duct structure. The adjustable inner secondary air duct device installed at the outlet of the inner secondary air channel of the burner and the adjustable primary air duct device installed at the outlet of the primary air channel are adjustable. By adjusting the positions of the inner secondary air duct and the adjustable primary air duct with a pull rod, the outlet area of the adjustable channel is incorporated into the outlet area of the inner secondary air channel or the primary air channel, thereby adjusting the outlet velocities of the inner secondary air and the primary air, and thus regulating the flow field at the burner outlet, adjusting the shape and size of the recirculation zone at the burner outlet, achieving the purpose of meeting the flexible peak shaving requirements, ensuring stable combustion at low loads, and avoiding burnout and slagging of the burner nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a layout schematic diagram of the swirl burner described in the present invention;

[0024] Figure 2 It is a structural schematic diagram of the swirl burner described in the present invention;

[0025] Figure 3 It is Figure 2 Schematic view in the direction A of

[0026] Figure 4 It is a partial schematic diagram of the adjustable air duct structure in the swirl burner described in the present invention;

[0027] Figure 5 It is a schematic diagram of the adjustable air duct structure parameters in the swirl burner described in the present invention;

[0028] Figure 6 It is a schematic diagram of the annular recirculation zone in the swirl burner described in the present invention;

[0029] Figure 7 This is a schematic diagram of the central recirculation zone of the swirl burner described in this invention;

[0030] In the diagram: 1. Swirl pulverized coal boiler, 2. Swirl pulverized coal burner, 3. Front wall, 4. Rear wall, 5. External secondary air duct, 6. Internal secondary air duct, 7. Adjustable duct, 8. Primary air duct, 9. External secondary air vent, 10. Internal secondary air vent, 11. Adjustable internal secondary air duct, 12. Adjustable primary air duct, 13. No. 2 roller, 14. No. 2 tie rod, 15. No. 1 front limiter baffle, 16. No. 2 rear limiter baffle, 17. Tangential blade, 18. Axially adjustable blade, 19. No. 1 tie rod, 20. No. 1 roller, 21. No. 2 front limiter baffle and 22. No. 2 rear limiter baffle. Detailed Implementation

[0031] Specific implementation method one: Combining Figures 1 to 7 This embodiment describes a swirl burner with an adjustable duct structure. The swirl burner consists of an outer secondary air duct 5, an inner secondary air duct 6, and a primary air duct 8, arranged from the outside to the inside. The outer secondary air duct 5 is equipped with tangential blades 17 and an outer secondary air vent 9 at its outlet. The inner secondary air duct 6 is equipped with axially adjustable blades 18 and an inner secondary air vent 10 at its outlet. An adjustable duct 7 is provided between the inner secondary air duct 6 and the primary air duct 8. An adjustable inner secondary air duct 11 and an adjustable primary air duct 12 are provided at the outlet of the adjustable duct 7.

[0032] Specific Implementation Method Two: Combining Figures 1 to 7 This embodiment differs from specific embodiment one in that the adjustable primary air duct 12 is fitted onto the inner tube in the adjustable channel 7, and N rows of rollers 20 (where N is a positive integer greater than 2) are provided between the adjustable primary air duct 12 and the inner tube in the adjustable channel 7. The adjustable primary air duct 12 is slidably connected to the inner tube in the adjustable channel 7 via the N rows of rollers 20. A pull rod 19 is provided at the end of the adjustable primary air duct 12 away from the outlet, and the tail of the pull rod 19 passes through the rear end plate of the adjustable channel 7 and extends to the outside of the swirl burner. Other components and connection methods are the same as in specific embodiment one.

[0033] Specific implementation method three: Combining Figures 1 to 7This embodiment differs from Specific Embodiment Two in that the adjustable inner secondary air duct 11 is inserted into the outer tube within the adjustable channel 7, and N rows of second-order rollers 13 are provided between the adjustable inner secondary air duct 11 and the outer tube in the adjustable channel 7, where N is a positive integer greater than 2. The adjustable inner secondary air duct 11 is slidably connected to the outer tube in the adjustable channel 7 via the N rows of second-order rollers 13. A second-order pull rod 14 is provided at the end of the adjustable inner secondary air duct 11 away from the outlet, and the tail of the second-order pull rod 14 passes through the rear end plate of the adjustable channel 7 and extends to the outside of the swirl burner. Other components and connection methods are the same as in Specific Embodiment Two.

[0034] Specific implementation method four: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment Three in that the inner tube of the adjustable channel 7 is equipped with a first front limiter baffle 15 and a first rear limiter baffle 16 that cooperate with the first roller 20. Other components and connections are the same as in Specific Embodiment Three.

[0035] Specific Implementation Method Five: Combining Figures 1 to 7 This embodiment differs from specific embodiment four in that the outer tube of the adjustable channel 7 is equipped with a second front limiter baffle 21 and a second rear limiter baffle 22 that cooperate with the second roller 13. Other components and connections are the same as in specific embodiment four.

[0036] Specific Implementation Method Six: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment One in that the inner diameter of the outlet of the adjustable primary air duct 12 is R1, the position of the adjustable primary air duct 12 when adjusted to the first front limit baffle 15 is 0, and the maximum distance the adjustable primary air duct 12 moves backward from the first front limit baffle 15 is L1. The inner diameter of the outlet of the adjustable inner secondary air duct 11 is R2, the position of the adjustable inner secondary air duct 11 when adjusted to the corresponding second front limit baffle 21 is 0, and the maximum distance the adjustable inner secondary air duct 11 moves backward from the second front limit baffle 21 is L2. Other components and connections are the same as in Specific Embodiment Five.

[0037] Specific implementation method seven: Combining Figures 1 to 7 This embodiment describes a method for using a swirl burner with an adjustable duct structure. The specific steps of the method are as follows:

[0038] First, install the swirl pulverized coal burner 2 on the front wall 3 and the rear wall 4 of the swirl pulverized coal boiler 1. The installation method adopted is opposed arrangement. The adjustable inner secondary air duct 11 and the adjustable primary air duct 12 are installed at the burner nozzle. The positions of the adjustable inner secondary air duct 11 and the adjustable primary air duct 12 are adjusted by the second pull rod 14 and the first pull rod 19 respectively. The outlet area of the adjustable channel 7 is incorporated into the outlet area of the inner secondary air channel 6 or the primary air channel 8, thereby adjusting the outlet air speeds of the inner secondary air and the primary air, and achieving the purpose of adjusting the shape and size of the recirculation zone at the burner outlet;

[0039] The air speed range in the primary air channel 8 is 22 - 25 m / s. When the boiler operates under the condition of 20 - 50% of the rated load, this condition is low-load operation. Through the first pull rod 19, the position of the adjustable primary air duct 12 is adjusted. When the Vdaf of the coal being burned > 30%, L1 = 50 - 250 mm, and the outlet air speed of the primary air channel 8 is reduced to 17 - 21 m / s; when 20 < Vdaf ≤ 30% of the coal being burned, L1 = 300 - 400 mm, and the outlet air speed of the primary air channel 8 is reduced to 15 - 18 m / s;

[0040] The air speed range in the inner secondary air channel 6 is 30 - 42 m / s. When the boiler operates under the condition of more than 50% of the rated load, this condition is high-load operation. Through the second pull rod 14, the position of the adjustable inner secondary air duct 11 is adjusted. When the Vdaf of the coal being burned > 30%, L2 = 250 - 400 mm, and the outlet air speed of the inner secondary air channel 6 is reduced to 20 - 30 m / s; when 20 < Vdaf ≤ 30% of the coal being burned, L2 = 50 - 250 mm, and the outlet air speed of the inner secondary air channel 6 is reduced to 25 - 32 m / s;

[0041] When the boiler operates under low-load conditions, a relatively large central recirculation zone is required at the outlet of the swirl burner. The operation is as follows: By adjusting the first pull rod 19, the position of the adjustable primary air duct 12 is adjusted. When the Vdaf of the coal being burned > 30%, L1 = 50 - 250 mm, and the outlet air speed of the primary air channel 8 is reduced to 17 - 21 m / s; when 20 < Vdaf ≤ 30% of the coal being burned, L1 = 300 - 400 mm, and the outlet air speed of the primary air channel ⑧ is reduced to 15 - 18 m / s. Through the above operations, reducing the outlet air speed of the primary air can form a relatively large and stable central recirculation zone at the outlet of the swirl burner. At this time, the distance between the starting point position of the central recirculation zone and the burner outlet is 0.15 < a < 0.2d, the length is 1.5d < l < 1.8d, and the diameter is 0.5d < D1 < 0.8d, where d is the diameter of the outer secondary air flare;

[0042] When the boiler is operating under high load conditions, an appropriate annular recirculation zone needs to be formed at the outlet of the tangential firing burner. The operation is as follows: By adjusting the second pull rod 14, the position of the adjustable inner secondary air duct 11 is adjusted. When the Vdaf of the coal being burned > 30%, L2 = 250 - 400 mm, and the outlet air velocity of the inner secondary air passage 6 is reduced to 20 - 30 m / s; when 20 < Vdaf ≤ 30% of the coal being burned, L2 = 50 - 250 mm, and the outlet air velocity of the inner secondary air passage 6 is reduced to 25 - 32 m / s. Through the above operations, the outlet air velocity of the inner secondary air is reduced, an appropriate annular recirculation zone is formed at the outlet of the tangential firing burner, and the pulverized coal is entrained with high-temperature flue gas through the annular recirculation zone and ignited, and the combustion is maintained. The distance a between the starting position of the annular recirculation zone and the burner outlet > 0.1d, the length is 0.6d < l < 1.0d, and the diameter is 0.2d < D2 < 0.4d, where d is the diameter of the outer secondary air flare.

[0043] The method described in this embodiment is applicable to coals with high volatile content, low ignition point, and low ash melting temperature, such as blended or pure burned Zhundong coal. Figure 7 This is a schematic diagram of the recirculation zone at the burner outlet in the present invention. In the figure l is the recirculation zone length, D1 is the diameter of the "elliptical" central recirculation zone, D2 is the diameter of the "heart-shaped" central recirculation zone, D3 is the diameter of the "annular" recirculation zone, and a is the distance between the burner outlet and the starting point of the recirculation zone. The method for adjusting the recirculation zone shape in the present invention is achieved through the following steps;

[0044] When the boiler is operating at 30% load and lower, a relatively large central recirculation zone is required at the burner outlet, and the starting point of the central recirculation zone is close to the primary air outlet. l is 1.5 - 2.0d, D1 is 0.5 - 0.8d, a is 0 - 0.15d, to meet the demand for stable combustion at ultra-low loads. As Figure 5 shown, the recirculation zone shape at this time is "elliptical";

[0045] When the boiler is operating at 30% - 50% load, a central recirculation zone is still required at the burner outlet. However, at the same time, to prevent slagging and burning problems at the burner nozzle, the starting point of the recirculation zone needs to be far from the primary air outlet. l is 1.0 - 1.5d, D2 is 0.35 - 0.5d, a is 0.15 - 0.25d. As Figure 6 shown, the recirculation zone shape at this time is "heart-shaped";

[0046] When the boiler is operating at 50% load and higher, an annular recirculation zone is required at the burner outlet. l is 0.6 - 1.0d, 2D3 is 0.25 - 0.35d, a > 0.25d. As Figure 7 shown, the recirculation zone shape at this time is "annular".

[0047] The present invention has been disclosed above with preferred embodiments. However, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications within the scope of the technical solution of the present invention to form equivalent embodiments of equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

[0048] Working principle:

[0049] The tangential pulverized coal burner 2 is installed on the front wall 3 and the rear wall 4 of the tangential pulverized coal boiler 1 in a opposed arrangement. The primary air enters the furnace through the primary air passage 8. The inner secondary air enters the furnace in a rotating form after passing through the axially adjustable vane 18 in the inner secondary air passage 6. The outer secondary air enters the furnace in a rotating form after passing through the tangential vane 17 in the outer secondary air passage 5. The adjustable inner secondary air pipe 11 and the adjustable primary air pipe 12 are installed at the outlet of the adjustable passage 7. The tie rods are respectively connected to the adjustable inner secondary air pipe 11 and the adjustable primary air pipe 12 and pass through the rear end plate of the adjustable passage. The inner diameter of the outlet of the adjustable primary air pipe 12 is R1. When the adjustable primary air pipe 12 is adjusted to the front limiter baffle, the position is point 0, and the distance moved backward from the front limiter baffle is L1. The inner diameter of the outlet of the adjustable inner secondary air pipe 11 is R2. When the adjustable inner secondary air pipe 11 is adjusted to the front limiter baffle, the position is point 0, and the distance moved backward from the front limiter baffle is L2. Both adjustable air pipes can be adjusted respectively through the tie rods. The wind speed range in the primary air passage 8 is 22 - 25 m / s, and the wind speed range in the inner secondary air passage 6 is 30 - 42 m / s. When burning coal with Vdaf > 30%, under the high load operation condition of the boiler, through the adjustment of the tie rods, L1 = 0 mm, L2 = 250 - 400 mm, and the wind speed at the outlet of the inner secondary air passage 6 is reduced to 20 - 30 m / s. Under the low load operation condition of the boiler, through the adjustment of the tie rods, L1 = 50 - 250 mm, L2 = 0 mm, and the wind speed at the outlet of the primary air passage 8 is reduced to 17 - 21 m / s. When burning coal with 20 < Vdaf ≤ 30%, under the high load operation condition of the boiler, through the adjustment of the tie rods, L1 = 0 mm, L2 = 50 - 250 mm, and the wind speed at the outlet of the inner secondary air passage 6 is reduced to 25 - 32 m / s. Under the low load operation condition of the boiler, through the adjustment of the tie rods, L1 = 300 - 400 mm, L2 = 0 mm, and the wind speed at the outlet of the primary air passage 8 is reduced to 15 - 18 m / s. Embodiment

[0050] Taking a supercritical 350MW boiler as an example, this boiler burns a blend of Zhundong coal and other bituminous coals, adopts a front and rear wall opposed firing method, and a total of 5 layers of burners are arranged (3 in the front and 2 in the rear), with 4 burners arranged in each layer. Before the burner modification, the minimum stable combustion load without oil injection of the boiler was 50%. During the annual shutdown for maintenance, it was found that the primary air expansion nozzle and the stable combustion ring of the burner were severely damaged, and related components needed to be frequently replaced.

[0051] According to the method described in this patent, a swirl pulverized coal burner with a variable recirculation zone ( Figure 2 the shown structure) was designed, and a model of this swirl pulverized coal burner was established in the laboratory. The size ratio of the model burner to the prototype burner was 1:4. A single-phase cold-state modeling test system was built to measure the flow field at the burner outlet. The test results are as follows:

[0052] (1) When the adjustable primary air duct is moved backward by 10 - 100mm and the adjustable inner secondary air duct is at the 0 position, the adjustable channel is incorporated into the inner secondary air channel area, increasing the inner secondary air outlet area. The primary air outlet velocity drops to 15 - 21m / s, and the inner secondary air outlet velocity is 30 - 42m / s. Under this condition, a large and stable central recirculation zone can be formed at the outlet of the swirl burner. The distance between the starting position of the recirculation zone and the burner outlet is 0.15 < a < 0.2d, the length is 1.5d < l < 1.8d, and the diameter is 0.5d < D1 < 0.8d.

[0053] (2) When the adjustable inner secondary air duct is moved backward by 10 - 100mm and the adjustable primary air duct is at the 0 position, the adjustable channel is incorporated into the inner secondary air channel area, increasing the inner secondary air outlet area. The inner secondary air outlet velocity drops to 20 - 32m / s, and the primary air outlet velocity is 22 - 25m / s. Under this condition, the starting position of the annular recirculation zone formed at the burner outlet is at a distance a > 0.1d from the burner outlet, the length is 0.6d < l < 1.0d, and the diameter is 0.2d < D2 < 0.4d.

[0054] Applying the method described in this patent to the above-mentioned supercritical 350MW boiler burning a blend of Zhundong coal and other bituminous coals, changing the recirculation zone at the burner outlet according to the load change meets the requirements of stable operation of the boiler under different loads. The specific method is as follows: When the boiler operates at a load of 30% and lower, determine the positions of the adjustable air ducts of the burner in actual operation according to the operation in the cold-state test result (1); when the boiler operates at a load of 50% and higher, determine the positions of the adjustable air ducts of the burner in actual operation according to the operation in the cold-state test result (2).

[0055] A supercritical 350MW boiler with opposed-wall combustion, employing the apparatus and method described in this invention, burns a blend of Zhundong coal and other bituminous coal. The minimum stable combustion load rate without oil injection is reduced to 30%, meeting the "dual carbon" target. No burn-out was observed in the primary air vents or the combustion stabilization rings of the burner. Considering the absence of burner burn-out, no fire extinguishing accidents, and the generation of low-load operation grid subsidies, the annual economic benefits are increased by approximately 60 million yuan.

Claims

1. A swirl burner with an adjustable duct structure, wherein the swirl burner comprises, from the outside to the inside, an outer secondary air duct (5), an inner secondary air duct (6), and a primary air duct (8), wherein the outer secondary air duct (5) is provided with tangential blades (17), and an outer secondary air flare (9) is installed at the outlet of the outer secondary air duct (5); wherein the inner secondary air duct (6) is provided with axially adjustable blades (18), and an inner secondary air flare (10) is installed at the outlet of the inner secondary air duct (6), characterized in that: An adjustable channel (7) is provided between the inner secondary air channel (6) and the primary air channel (8), and an adjustable inner secondary air duct (11) and an adjustable primary air duct (12) are provided at the outlet of the adjustable channel (7). The adjustable primary air duct (12) is fitted onto the inner tube in the adjustable channel (7), and there are N rows of No. 1 rollers (20) between the adjustable primary air duct (12) and the inner tube in the adjustable channel (7), where N is a positive integer greater than 2. The adjustable primary air duct (12) is slidably connected to the inner tube in the adjustable channel (7) through the N rows of No. 1 rollers (20). A No. 1 pull rod (19) is provided at the end of the adjustable primary air duct (12) away from the air outlet. The tail of the No. 1 pull rod (19) passes through the rear end plate of the adjustable channel (7) and extends to the outside of the swirl burner. The adjustable inner secondary air duct (11) is inserted into the outer tube in the adjustable channel (7), and there are N rows of No. 2 rollers (13) between the adjustable inner secondary air duct (11) and the outer tube in the adjustable channel (7), where N is a positive integer greater than 2. The adjustable inner secondary air duct (11) is slidably connected to the outer tube in the adjustable channel (7) through the N rows of No. 2 rollers (13). The end of the adjustable inner secondary air duct (11) away from the air outlet is provided with a No. 2 pull rod (14). The tail of the No. 2 pull rod (14) passes through the rear end plate of the adjustable channel (7) and extends to the outside of the swirl burner.

2. The swirl burner with an adjustable duct structure according to claim 1, characterized in that: The inner tube of the adjustable channel (7) is provided with a front limiter baffle (15) and a rear limiter baffle (16) that cooperate with the first roller (20).

3. The swirl burner with an adjustable duct structure according to claim 2, characterized in that: The adjustable channel (7) has a front limiter baffle (21) and a rear limiter baffle (22) on the outer tube that cooperate with the second roller (13).

4. A swirl burner with an adjustable duct structure according to claim 3, characterized in that: The inner diameter of the outlet of the adjustable primary air duct (12) is R1. When the adjustable primary air duct (12) is adjusted to the first front limiter baffle (15), the position is 0 point. The maximum distance that the adjustable primary air duct (12) moves backward from the first front limiter baffle (15) is L1. The inner diameter of the outlet of the adjustable inner secondary air duct (11) is R2. When the adjustable inner secondary air duct (11) is adjusted to the corresponding second front limiter baffle (21), the position is 0 point. The maximum distance that the adjustable inner secondary air duct (11) moves backward from the second front limiter baffle (21) is L2.

5. A method of using a swirl burner based on any one of the adjustable duct structures of claims 1 to 4, characterized in that: The specific steps of the method are as follows: First, the swirl pulverized coal burner (2) is installed on the front wall (3) and rear wall (4) of the swirl pulverized coal boiler (1). The installation method is a counter-arrangement. The burner nozzle is equipped with an adjustable internal secondary air duct (11) and an adjustable primary air duct (12). The positions of the internal secondary air duct (11) and the adjustable primary air duct (12) are adjusted by the second tie rod (14) and the first tie rod (19) respectively. The outlet area of ​​the adjustable channel (7) is incorporated into the outlet area of ​​the internal secondary air channel (6) or the primary air channel (8), thereby adjusting the outlet wind speed of the internal secondary air and the primary air to achieve the purpose of adjusting the shape and size of the recirculation zone at the burner outlet. The wind speed range in the primary air duct (8) is 22 - 25 m / s. When the boiler operates under the condition of 20 - 50% of the rated load, this condition is low-load operation. The position of the adjustable primary air duct (12) is adjusted by the first pull rod (19). When the Vdaf of the coal used is > 30%, L1 = 50 - 250 mm, and the wind speed at the outlet of the primary air duct (8) is reduced to 17 - 21 m / s; when 20 < Vdaf ≤ 30% of the coal used, L1 = 300 - 400 mm, and the wind speed at the outlet of the primary air duct (8) is reduced to 15 - 18 m / s; The wind speed range in the inner secondary air duct (6) is 30 - 42 m / s. When the boiler operates under the condition of more than 50% of the rated load, this condition is high-load operation. The position of the adjustable inner secondary air duct (11) is adjusted by the second pull rod (14). When the Vdaf of the coal used is > 30%, L2 = 250 - 400 mm, and the wind speed at the outlet of the inner secondary air duct (6) is reduced to 20 - 30 m / s; when 20 < Vdaf ≤ 30% of the coal used, L2 = 50 - 250 mm, and the wind speed at the outlet of the inner secondary air duct (6) is reduced to 25 - 32 m / s; When the boiler operates under low-load conditions, the operation is as follows: By adjusting the first pull rod (19), the position of the adjustable primary air duct (12) is adjusted. When the Vdaf of the coal used is > 30%, L1 = 50 - 250 mm, and the wind speed at the outlet of the primary air duct (8) is reduced to 17 - 21 m / s; when 20 < Vdaf ≤ 30% of the coal used, L1 = 300 - 400 mm, and the wind speed at the outlet of the primary air duct (8) is reduced to 15 - 18 m / s. Through the above operations, the wind speed at the primary air outlet is reduced. At this time, the distance between the starting point of the central recirculation zone and the burner outlet is 0.15 < a < 0.2d, the length is 1.5d < l < 1.8d, and the diameter is 0.5d < D1 < 0.8d, where d is the diameter of the outer secondary air flare; When the boiler operates under high-load conditions, the operation is as follows: By adjusting the second pull rod (14), the position of the adjustable inner secondary air duct (11) is adjusted. When the Vdaf of the coal used is > 30%, L2 = 250 - 400 mm, and the wind speed at the outlet of the inner secondary air duct (6) is reduced to 20 - 30 m / s; when 20 < Vdaf ≤ 30% of the coal used, L2 = 50 - 250 mm, and the wind speed at the outlet of the inner secondary air duct (6) is reduced to 25 - 32 m / s. Through the above operations, the wind speed at the inner secondary air outlet is reduced. The pulverized coal is ignited by entraining high-temperature flue gas through the annular recirculation zone and maintains combustion. The distance between the starting point of the annular recirculation zone and the burner outlet is a > 0.1d, the length is 0.6d < l < 1.0d, and the diameter is 0.2d < D2 < 0.4d, where d is the diameter of the outer secondary air flare.

Images