Air distribution system and coupled control method suitable for tangentially fired pulverized coal boiler power field adjustment

Abstract

The present application belongs to tangential firing technology field, and relates to a kind of air distribution system and coupling control method suitable for tangential firing pulverized coal boiler power field adjustment, system includes main burner, main burner includes main air box, multiple secondary air nozzles are rotationally installed at the outlet of main air box, multiple pulverized coal nozzles are fixedly installed at the outlet of main air box, secondary air nozzle and pulverized coal nozzle are sequentially staggered in vertical direction, and secondary air nozzle rotates in the θ angle range in horizontal direction.The method includes: judging the situation of burning coal quality or the situation of boiler operation;Control the rotation direction of the secondary air nozzle of main burner and the opening of secondary air damper.The present application is designed by the secondary air nozzle structure of main burner, so that the air volume and jet angle of the secondary air nozzle of main burner can be adjusted, and the adjustment effect of combustion tangential circle and boiler operation is prominent;The coupling adjustment of secondary air volume and jet angle can realize the effect of accurately controlling hot tangential circle and pulverized coal combustion process.

Description

Technical Field

[0001] This invention relates to the field of tangential combustion technology, and in particular to an air distribution system and coupling control method suitable for adjusting the power field of tangential combustion pulverized coal boilers. Background Technology

[0002] Tangential combustion technology is one of the most widely used and mature pulverized coal combustion technologies in my country's coal-fired power plants. Through a burner design positioned at or near the corner of the furnace wall, a rotating fireball is formed inside the furnace. Several flame streams mutually support and promote combustion, resulting in strong combustion stability, uniform mixing of pulverized coal and air, and low pollutant emissions. Tangential combustion is highly efficient and economical, with extremely high flame coverage and a uniform temperature distribution within the furnace, effectively improving pulverized coal burnout rate and combustion efficiency. However, tangential combustion technology also has some potential drawbacks: when the diameter of the tangential circle inside the furnace is too large, it can easily lead to flame erosion of the water-cooled walls, high-temperature corrosion, slagging, and coking. Uneven primary or secondary air flow at each corner may cause the flame to deflect, leading to the aforementioned problems in localized areas of the water-cooled walls, and even causing overheating and tube rupture of the heating surfaces. Therefore, controlling the size and position of the hot tangential circle inside the furnace is a crucial factor in ensuring the effectiveness of tangential combustion. Currently, tangential combustion technology mainly regulates pulverized coal combustion conditions by adjusting the secondary air volume through secondary air dampers: Firstly, it adjusts the secondary air volume distribution ratio in the main burner area along the furnace height to achieve different air distribution patterns, such as pagoda-shaped, waist-shaped, inverted pagoda-shaped, and spindle-shaped patterns. Secondly, it adjusts the air volume ratio between direct-blown secondary air and deflected secondary air; increasing the deflected secondary air volume results in a larger tangential circle, and vice versa. These air distribution adjustment methods are mature, but their adaptability to changes in coal type and load is limited. This is mainly because the secondary air nozzle area and angle are fixed after the burner design and installation, limiting the adjustable range and actual effect, especially in terms of the ability to adjust the size and position of the hot tangential circle within the furnace. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problems existing in the background art. To this end, an air distribution system and coupling control method suitable for adjusting the power field of a tangentially burning pulverized coal boiler are provided. This system can significantly enhance the adjustment effect of the secondary air in the furnace on the power field in the furnace, improve the adjustment effect of the tangentially burning cold and hot state, increase the boiler's adaptability to coal types, and improve the combustion conditions.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An air distribution system suitable for adjusting the power field of a tangentially circular pulverized coal boiler includes a main burner arranged at or near the corner of the furnace wall. The main burner includes a main air box. Multiple secondary air nozzles are rotatably installed at the outlet of the main air box, and multiple pulverized coal nozzles are fixedly installed at the outlet of the main air box. The secondary air nozzles and pulverized coal nozzles are arranged alternately in the vertical direction. The secondary air nozzles rotate within an angle range of θ in the horizontal direction. Multiple secondary air dampers are installed at the inlet of the main air box, and the secondary air dampers correspond one-to-one with the secondary air nozzles and pulverized coal nozzles.

[0006] The following is a further defined technical solution of the system in this invention, which also includes a separate burnout air burner. The separate burnout air burner is located at a distance H above the main burner. The separate burnout air burner includes a burnout air box. Multiple burnout air nozzles are rotatably installed at the outlet of the burnout air box. The multiple burnout air nozzles are arranged sequentially in the vertical direction. The burnout air nozzles rotate within a β angle range in the horizontal direction. Multiple burnout air dampers are installed at the inlet of the burnout air box. The burnout air dampers correspond one-to-one with the burnout air nozzles.

[0007] The following is a further technical solution for the system in this invention: a bottom air nozzle is provided at the bottom of the outlet of the main air box, and a secondary air damper corresponding to the bottom air nozzle is installed at the inlet of the main air box.

[0008] The following is a further defined technical solution for the system in this invention: the ventilation channel corresponding to each of the secondary air nozzles, the ventilation channel corresponding to each of the pulverized coal nozzles, the ventilation channel corresponding to the bottom air nozzle, and the ventilation channel corresponding to each of the burnout air nozzles all operate independently and do not affect each other.

[0009] The following is a further technical solution for the system in this invention: each of the secondary air nozzles rotates and operates independently, and each of the burnout air nozzles rotates and operates independently.

[0010] The following is a further defined technical solution of the system in this invention: at least two of the secondary air nozzles rotate in groups, and at least two of the burnout air nozzles rotate in groups.

[0011] The following is a further defined technical solution for the system in this invention: the range of θ is 10°~50°, and the range of β is 10°~60°.

[0012] The coupling control method, implemented based on the aforementioned air distribution system, includes: The system uses image recognition modules or sensors to determine the quality of the coal used or the operating status of the boiler; Control the rotation direction of the secondary air nozzle of the main burner and the opening degree of the secondary air damper.

[0013] The following is a further technical solution for the method of the present invention, wherein the coal quality includes enhanced slagging properties, increased sulfur content, decreased volatile matter, increased moisture content, and decreased calorific value; When the coal used is characterized by increased slagging, the secondary air nozzle rotates in the opposite direction, and the opening of the secondary air damper gradually decreases from bottom to top. When the sulfur content of the coal increases, the secondary air nozzle rotates in the opposite direction, and the opening of the secondary air damper gradually increases from bottom to top. When the volatile matter content of the coal being burned decreases, the secondary air nozzle rotates in the forward direction, and the opening of the secondary air damper gradually decreases from bottom to top. When the coal used has increased moisture content, the secondary air nozzle rotates in the opposite direction, and the opening of the secondary air damper gradually decreases from bottom to top. When the calorific value of the coal being burned decreases, the secondary air nozzle rotates in the forward direction, and the opening of the secondary air damper gradually increases from bottom to top. The boiler operating status includes NO. x The emissions were too high, the fly ash carbon content was too high, the flue gas temperature deviation was too large, and the combustion tangent circle was biased towards corner A and the combustion tangent circle was biased towards the left wall. When the boiler's operating status is NO x When the emission value is too high, the secondary air nozzle rotates in the opposite direction, and the opening of the secondary air damper gradually increases from bottom to top; When the boiler is operating under conditions where the carbon content of fly ash is high, the secondary air nozzles rotate in the forward direction, and the opening of the secondary air dampers is consistent both vertically. When the boiler is operating under conditions where the flue gas temperature deviation is large, the lower half of the secondary air nozzle remains unchanged while the upper half rotates in the opposite direction, and the opening of the secondary air damper gradually decreases from bottom to top. When the boiler is operating in a state where the combustion tangent is deviated towards angle A, angle A of the secondary air nozzle rotates in the opposite direction, the upstream adjacent angle of angle A rotates in the opposite direction, the downstream adjacent angle of angle A rotates in the forward direction, and the downstream partition angle of angle A rotates in the forward direction; the opening of the secondary air damper increases as a whole at angle A, decreases as a whole at the upstream adjacent angle of angle A, increases as a whole at the downstream adjacent angle of angle A, and decreases as a whole at the downstream partition angle of angle A. When the boiler is operating in a state where the combustion tangent is biased towards the left wall, the upper left corner of the secondary air nozzle rotates in the opposite direction, the lower left corner rotates in the opposite direction, the upper right corner rotates in the forward direction, and the lower right corner rotates in the opposite direction; the opening of the secondary air damper increases as a whole at the upper left corner, increases as a whole at the lower left corner, decreases as a whole at the upper right corner, and decreases as a whole at the lower right corner.

[0014] The following is a further technical solution that defines the method of the present invention: a separate burnout air burner is set at a distance H above the main burner; The system uses image recognition modules or sensors to determine the quality of the coal used or the operating status of the boiler; Control the rotation direction of the secondary air nozzle of the main burner and the opening of the secondary air damper; Control the rotation direction of the burnout air nozzle of the separate burnout air burner and the opening degree of the burnout air damper; The characteristics of the coal used include increased slagging properties, increased sulfur content, decreased volatile matter, increased moisture content, and decreased calorific value. When the coal used has increased slagging properties, the secondary air nozzle rotates in the opposite direction, the opening of the secondary air damper decreases overall and gradually decreases from bottom to top, the burnout air nozzle rotates in the opposite direction, and the opening of the burnout air damper increases overall and gradually increases from bottom to top. When the sulfur content of the coal increases, the secondary air nozzles rotate in the opposite direction, the opening of the secondary air damper increases overall and gradually increases from bottom to top, the burnout air nozzles rotate in the opposite direction, and the opening of the burnout air damper decreases overall and gradually decreases from bottom to top. When the volatile matter content of the coal being burned decreases, the secondary air nozzle rotates in the forward direction, the opening of the secondary air damper increases overall and gradually decreases from bottom to top, the burnout air nozzle rotates in the forward direction, and the opening of the burnout air damper decreases overall and gradually decreases from bottom to top. When the coal used has increased moisture content, the secondary air nozzle rotates in the reverse direction, the opening of the secondary air damper increases overall and gradually decreases from bottom to top, and the burnout air nozzle rotates in the forward direction, the opening of the burnout air damper decreases overall and gradually increases from bottom to top. When the calorific value of the coal being burned decreases, the secondary air nozzle rotates in the forward direction, the opening of the secondary air damper increases overall and gradually increases from bottom to top, the burnout air nozzle rotates in the forward direction, and the opening of the burnout air damper decreases overall and gradually decreases from bottom to top. The boiler operating status includes NO. x The emissions were too high, the fly ash carbon content was too high, the flue gas temperature deviation was too large, and the combustion tangent circle was biased towards corner A and the combustion tangent circle was biased towards the left wall. When the boiler's operating status is NO x When the emission value is too high, the secondary air nozzle rotates in the opposite direction, the opening of the secondary air damper decreases as a whole and gradually increases from bottom to top, the burnout air nozzle rotates in the opposite direction, and the opening of the burnout air damper increases as a whole and gradually increases from bottom to top. When the boiler is operating under conditions where the carbon content of fly ash is high, the secondary air nozzles rotate in the forward direction, the opening of the secondary air dampers increases as a whole and is consistent from top to bottom, the burnout air nozzles rotate in the forward direction, and the opening of the burnout air dampers decreases as a whole and gradually decreases from bottom to top. When the boiler is operating under conditions where the flue gas temperature deviation is large, the lower half of the secondary air nozzle remains unchanged while the upper half rotates in the opposite direction. The opening of the secondary air damper decreases overall and gradually decreases from bottom to top. The burnout air nozzle rotates in the opposite direction, and the opening of the burnout air damper increases overall and gradually increases from bottom to top. When the boiler is operating in a state where the combustion tangent is biased towards angle A, the secondary air nozzle rotates in the opposite direction at angle A, the upstream adjacent angle rotates in the opposite direction, the downstream adjacent angle rotates in the forward direction, and the downstream partition angle rotates in the forward direction. The opening of the secondary air damper increases as a whole at angle A, decreases as a whole at the upstream adjacent angle, increases as a whole at the downstream adjacent angle, and decreases as a whole at the downstream partition angle. The burnout air nozzle does not rotate, and the opening of the burnout air damper decreases as a whole. When the boiler is operating in a state where the combustion tangent is biased towards the left wall, the upper left corner of the secondary air nozzle rotates in the opposite direction, the lower left corner rotates in the opposite direction, the upper right corner rotates in the forward direction and the lower right corner rotates in the opposite direction, the opening of the secondary air damper increases as a whole at the upper left corner, increases as a whole at the lower left corner, decreases as a whole at the upper right corner and decreases as a whole at the lower right corner, the burnout air nozzle does not rotate, and the opening of the burnout air damper decreases as a whole.

[0015] Compared with the prior art, the present invention has the following technical effects: This invention, through the structural design of the secondary air nozzle of the main burner, makes both the air volume and jet angle of the secondary air nozzle adjustable, resulting in a significant effect on regulating the combustion tangential circle and boiler operation. The coupled adjustment of the secondary air volume and jet angle can achieve precise control of the hot tangential circle and the pulverized coal combustion process. The system and control method of this invention greatly expand the adaptability of the boiler burner to different coal types, and have a significant advantage in dealing with coal types with a wide range of slagging properties and sulfur content, thus significantly optimizing the boiler combustion conditions.

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

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

[0018] Figure 1 This is an elevation view of the main burner layout in the system of this invention; Figure 2 This is a plan view of the main burner in the system of the present invention; Figure 3 This is a plan view of the burner with separate burnout air in the system of the present invention; Figure 4 This is an elevation layout diagram of the burner with separate burnout air in the system of this invention.

[0019] Attached reference numerals: 1. Secondary air nozzle; 2. Pulverized coal nozzle; 3. Bottom air nozzle; 4. Main air box; 5. Secondary air damper; 6. Combustion air box; 7. Combustion air damper; 8. Combustion air nozzle. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0023] Example 1: like Figures 1-2The diagram shows a schematic of the air distribution system for adjusting the power field of a tangentially fired pulverized coal boiler, taking a 600MW-class pulverized coal boiler as an example. The boiler adopts tangentially fired technology, and the pulverizing system is equipped with six coal mills. The air distribution system for adjusting the power field of the tangentially fired pulverized coal boiler consists of secondary air nozzle 1, pulverized coal nozzle 2, bottom air nozzle 3, main air box 4, and secondary air dampers 5. The secondary air nozzle 1, pulverized coal nozzle 2, and bottom air nozzle 3 are located in the main air box 4, and the pulverized coal nozzle 2 is designed with a perimeter secondary air channel. Multiple secondary air dampers 5 are located at the inlet of the main air box 4, corresponding one-to-one with the aforementioned nozzles (i.e., secondary air nozzle 1, pulverized coal nozzle 2, and bottom air nozzle 3). The secondary air intake of each nozzle can be adjusted individually. The adjustable flow area of ​​the damper is 1.5 to 3.5 times the designed flow area of ​​the secondary air of the corresponding nozzle, and the opening range is fully open to fully closed. When the damper is fully closed, the air leakage ratio is no more than 1%. The bottom air nozzle 3 is fixed at the bottom of the main air box 4 and has no rotation function. The secondary air nozzle 1 can rotate within a horizontal angle range of θ. Rotation can be achieved manually, by an electric actuator, or by a pneumatic actuator. The rotation can be performed individually, in groups, or in groups of several adjacent layers. The range of θ is 10° to 50°. The pulverized coal nozzle 2 is fixed inside the main air box 4 and has no rotation function. The centerline of the main air box 4 forms an imaginary tangent circle within the boiler furnace.

[0024] This embodiment takes a clockwise tangent direction as an example, with clockwise being the positive direction and counterclockwise being the negative direction. In the following text, "forward rotation" and "reverse rotation" refer to the burner state before the change of the coal quality used in the boiler and before the change of the boiler operating parameters.

[0025] The secondary air nozzle 1 can rotate left and right in the horizontal direction, thereby changing the direction of the secondary air flow at the outlet, i.e., changing the size of the imaginary tangential circle of the secondary air. When the secondary air nozzle 1 rotates in the forward direction, the combustion tangential circle increases accordingly, and the oxygen content near the wall increases; when the secondary air nozzle 1 rotates in the reverse direction, the combustion tangential circle decreases accordingly, and the oxygen content near the wall decreases. Adjusting the opening of the secondary air damper 5 can change the flow rate of the secondary air in each nozzle, thereby changing the velocity of the secondary air at the outlet, i.e., changing the amount of secondary air flow, adjusting the airflow rigidity and penetration ability. Through the coupled control of the horizontal jet angle of the secondary air nozzle 1 and the opening of the secondary air damper 5, the boiler combustion dynamic field can achieve flexible adjustment of the tangential circle size, oxygen distribution, temperature distribution, and near-water-cooled wall atmosphere to adapt to different coal types and address issues such as coking, slagging, and high-temperature corrosion in the combustion zone within the furnace.

[0026] For example, when the coal actually burned in the boiler has a stronger slagging tendency than the designed coal, the secondary air nozzle 1 rotates in the opposite direction. This reduces the imaginary tangential circle corresponding to the centerline of the secondary air flow at its outlet, and consequently reduces the actual combustion tangential circle diameter. This helps lower the flue gas temperature near the water-cooled wall and prevents the risk of flame brushing against the wall. The opening of the secondary air damper 5 follows a pattern of larger opening at the bottom of the burner and smaller opening at the top, i.e., a pagoda-style air distribution mode. This can reduce the flue gas temperature at the bottom of the furnace screen and prevent slagging on the high-temperature heating surfaces. Simultaneously, the secondary air nozzle 1 can further adopt a pattern of smaller reverse rotation angle at the bottom of the burner and larger reverse rotation angle at the top, i.e., the counterclockwise reverse tangential degree of the secondary air nozzle 1 gradually increases from bottom to top. This compensates for the increasing trend of the hot tangential circle diameter in the furnace height direction, better preventing the risk of slagging on the heating surfaces from the top of the burner to the bottom of the screen.

[0027] For example, when the calorific value of the coal actually burned in the boiler is lower than that of the designed coal, the secondary air nozzle 1 rotates in the forward direction. The imaginary tangent circle corresponding to the center line of the secondary air flow at its outlet increases, and the actual combustion tangent circle diameter will increase accordingly. This is beneficial to enhance the disturbance intensity of the combustion fireball and the air-coal mixing intensity, thereby improving combustion efficiency and combustion stability. The opening degree of the secondary air damper 5 follows the pattern of a small opening at the bottom of the burner and a large opening at the top, i.e., an inverted pagoda air distribution mode. This can strengthen the ignition of pulverized coal in the upper part of the burner, promote the upward movement of the high-temperature zone in the height direction of the furnace, increase the flue gas temperature at the furnace outlet, and improve the main and reheat steam temperatures.

[0028] Based on boiler operating experience, the boiler dynamic field is adjusted using the coupling control method shown in the table below: Table 1: Coupling control based on coal quality;

[0029] Table 2: Coupled control based on boiler operating parameters;

[0030] Note: In Table 2, "A" in serial number 4 refers to a burner in a certain corner; serial number 5 in Table 2 uses the "left wall" as an example, and the other three walls are similar.

[0031] Under the coupled control mode of secondary air nozzle 1 and secondary air damper 5, the combustion tangential diameter and excess air coefficient of the boiler combustion zone can be adjusted in different areas, which optimizes the combustion intensity and oxygen distribution of pulverized coal and enhances its adaptability to different coal types. The coupled adjustment mode of secondary air flow rate, momentum and airflow injection direction solves the drawback of poor adjustment effect of the current fixed secondary air nozzle, which can significantly improve the dynamic field of tangential combustion pulverized coal boiler and improve combustion efficiency and combustion stability.

[0032] Example 2: like Figures 1-4The diagram shows a schematic of the air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler, taking a 600MW-class pulverized coal boiler as an example. Compared with Example 1, Example 2 adds a separate burnout air burner at a distance H above the main burner. The separate burnout air burner consists of a burnout air box 6, burnout air dampers 7, and multiple burnout air nozzles 8. The imaginary tangential diameter of the installation centerline of the burnout air box 6 is 0, meaning that the diagonal airflows are completely opposite. The multiple burnout air dampers 7 are located at the inlet of the burnout air box 6, corresponding one-to-one with the aforementioned burnout air nozzles, and can individually adjust the burnout air intake of each nozzle, with an opening range from fully open to fully closed. The burnout air nozzle 8 can rotate within a horizontal angle range of β. Rotation can be achieved manually, by an electric actuator, or by a pneumatic actuator. The rotation can be performed individually, in a group, or by rotating several layers of burnout air nozzles together. The range of β is 10° to 60°.

[0033] Separate burnout air burners can directly adjust the flue gas field in the pulverized coal burnout zone of the boiler, further improving the overall boiler dynamic field and optimizing the flue gas parameters at the furnace outlet. The coupling control method shown in the table below is recommended for adjusting the boiler dynamic field: Table 3: Coupled control based on coal quality;

[0034] Table 4: Coupled control based on boiler operating parameters;

[0035] Note: In Table 4, "A" in serial number 4 refers to a burner in a certain corner; serial number 5 in Table 4 uses the "left wall" as an example, and the other three walls are similar.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention's technical solution. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention's technical solution should be covered within the protection scope of the present invention.

Claims

1. An air distribution system suitable for adjusting the power field of a tangentially circular pulverized coal boiler, characterized in that, The furnace includes a main burner arranged at or near the corner of the furnace wall. The main burner includes a main air box (4). Multiple secondary air nozzles (1) are rotatably installed at the outlet of the main air box (4). Multiple pulverized coal nozzles (2) are fixedly installed at the outlet of the main air box (4). The secondary air nozzles (1) and pulverized coal nozzles (2) are arranged alternately in the vertical direction. The secondary air nozzles (1) rotate within an angle range of θ in the horizontal direction. Multiple secondary air dampers (5) are installed at the inlet of the main air box (4). The secondary air dampers (5) correspond one-to-one with the secondary air nozzles (1) and pulverized coal nozzles (2).

2. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 1, characterized in that, It also includes a separate burnout air burner, which is located at a distance H above the main burner. The separate burnout air burner includes a burnout air box (6), and multiple burnout air nozzles (8) are rotatably installed at the outlet of the burnout air box (6). The multiple burnout air nozzles (8) are arranged sequentially in the vertical direction. The burnout air nozzles (8) rotate within a β angle range in the horizontal direction. Multiple burnout air dampers (7) are installed at the inlet of the burnout air box (6), and the burnout air dampers (7) correspond one-to-one with the burnout air nozzles (8).

3. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 1, characterized in that, The bottom air nozzle (3) is provided at the bottom of the outlet of the main air box (4), and a secondary air damper (5) corresponding to the bottom air nozzle (3) is installed at the inlet of the main air box (4).

4. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 2, characterized in that, The ventilation channels corresponding to each of the secondary air nozzles (1), each of the pulverized coal nozzles (2), the bottom air nozzles (3), and each of the burnout air nozzles (8) operate independently and do not affect each other.

5. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 2, characterized in that, Each of the secondary air nozzles (1) rotates and operates independently, and each of the burnout air nozzles (8) rotates and operates independently.

6. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 2, characterized in that, At least two of the secondary air nozzles (1) rotate in groups, and at least two of the burnout air nozzles (8) rotate in groups.

7. The air distribution system for adjusting the power field of a tangentially burning pulverized coal boiler as described in claim 2, characterized in that, The range of θ is 10° to 50°, and the range of β is 10° to 60°.

8. A coupling control method, implemented based on the air distribution system according to any one of claims 1-7, characterized in that, include: The system uses image recognition modules or sensors to determine the quality of the coal used or the operating status of the boiler; Control the rotation direction of the secondary air nozzle (1) of the main burner and the opening degree of the secondary air damper (5).

9. The coupling control method as described in claim 8, characterized in that, The characteristics of the coal used include increased slagging properties, increased sulfur content, decreased volatile matter, increased moisture content, and decreased calorific value. When the coal used is characterized by increased slagging, the secondary air nozzle (1) rotates in the opposite direction, and the opening of the secondary air damper (5) gradually decreases from bottom to top. When the sulfur content of the coal increases, the secondary air nozzle (1) rotates in the opposite direction, and the opening of the secondary air damper (5) gradually increases from bottom to top. When the volatile matter content of the coal being burned decreases, the secondary air nozzle (1) rotates in the forward direction, and the opening of the secondary air damper (5) gradually decreases from bottom to top. When the coal used has increased moisture content, the secondary air nozzle (1) rotates in the opposite direction, and the opening of the secondary air damper (5) gradually decreases from bottom to top. When the calorific value of the coal being burned decreases, the secondary air nozzle (1) rotates in the forward direction, and the opening of the secondary air damper (5) gradually increases from bottom to top. The boiler operating conditions include high NOx emissions, high fly ash carbon content, large flue gas temperature deviation, combustion tangent circle deviating from corner A, and combustion tangent circle deviating from the left wall; When the boiler is operating under conditions where NOx emissions are high, the secondary air nozzle (1) rotates in the opposite direction, and the opening of the secondary air damper (5) gradually increases from bottom to top. When the boiler is operating under conditions where the carbon content of fly ash is too high, the secondary air nozzle (1) rotates in the forward direction, and the opening of the secondary air damper (5) is consistent both vertically. When the boiler is operating under conditions where the flue gas temperature deviation is large, the lower half of the secondary air nozzle (1) remains unchanged while the upper half rotates in the opposite direction, and the opening of the secondary air damper (5) gradually decreases from bottom to top. When the boiler is operating in a state where the combustion tangent is biased towards angle A, the angle A of the secondary air nozzle (1) rotates in the opposite direction, the upstream adjacent angle of angle A rotates in the opposite direction, the downstream adjacent angle of angle A rotates in the positive direction, and the downstream partition angle of angle A rotates in the positive direction; the opening of the secondary air damper (5) increases as a whole at angle A, decreases as a whole at the upstream adjacent angle of angle A, increases as a whole at the downstream adjacent angle of angle A, and decreases as a whole at the downstream partition angle of angle A. When the boiler is operating in a state where the combustion tangent is biased towards the left wall, the upper left corner of the secondary air nozzle (1) rotates in the opposite direction, the lower left corner rotates in the opposite direction, the upper right corner rotates in the forward direction, and the lower right corner rotates in the opposite direction; the opening of the secondary air damper (5) increases as much as the upper left corner, increases as much as the lower left corner, decreases as much as the upper right corner, and decreases as much as the lower right corner.

10. The coupling control method as described in claim 8, characterized in that, A separate burnout air burner is installed at a distance H above the main burner; The system uses image recognition modules or sensors to determine the quality of the coal used or the operating status of the boiler; Control the rotation direction of the secondary air nozzle (1) of the main burner and the opening degree of the secondary air damper (5); Control the rotation direction of the burnout air nozzle (8) of the separate burnout air burner and the opening degree of the burnout air damper (7); The characteristics of the coal used include increased slagging properties, increased sulfur content, decreased volatile matter, increased moisture content, and decreased calorific value. When the coal used is characterized by increased slagging, the secondary air nozzle (1) rotates in the opposite direction, the opening of the secondary air damper (5) decreases as a whole and gradually decreases from bottom to top, the burnout air nozzle (8) rotates in the opposite direction, and the opening of the burnout air damper (7) increases as a whole and gradually increases from bottom to top. When the sulfur content of the coal increases, the secondary air nozzle (1) rotates in the opposite direction, the opening of the secondary air damper (5) increases as a whole and gradually increases from bottom to top, the burnout air nozzle (8) rotates in the opposite direction, and the opening of the burnout air damper (7) decreases as a whole and gradually decreases from bottom to top. When the volatile matter content of the coal being burned decreases, the secondary air nozzle (1) rotates in the forward direction, the opening of the secondary air damper (5) increases as a whole and gradually decreases from bottom to top, the burnout air nozzle (8) rotates in the forward direction, and the opening of the burnout air damper (7) decreases as a whole and gradually decreases from bottom to top. When the coal used has increased moisture content, the secondary air nozzle (1) rotates in the opposite direction, the opening of the secondary air damper (5) increases as a whole and gradually decreases from bottom to top, the burnout air nozzle (8) rotates in the forward direction, and the opening of the burnout air damper (7) decreases as a whole and gradually increases from bottom to top. When the calorific value of the coal being burned decreases, the secondary air nozzle (1) rotates in the forward direction, the opening of the secondary air damper (5) increases as a whole and gradually increases from bottom to top, the burnout air nozzle (8) rotates in the forward direction, and the opening of the burnout air damper (7) decreases as a whole and gradually decreases from bottom to top. The boiler operating conditions include high NOx emissions, high fly ash carbon content, large flue gas temperature deviation, combustion tangent circle deviating from corner A, and combustion tangent circle deviating from the left wall; When the boiler is operating under conditions where NOx emissions are high, the secondary air nozzle (1) rotates in the opposite direction, the opening of the secondary air damper (5) decreases overall and gradually increases from bottom to top, the burnout air nozzle (8) rotates in the opposite direction, and the opening of the burnout air damper (7) increases overall and gradually increases from bottom to top. When the boiler is operating under conditions where the carbon content of fly ash is too high, the secondary air nozzle (1) rotates in the forward direction, the opening of the secondary air damper (5) increases as a whole and is consistent from top to bottom, the burnout air nozzle (8) rotates in the forward direction, and the opening of the burnout air damper (7) decreases as a whole and gradually decreases from bottom to top. When the boiler is operating under conditions where the flue gas temperature deviation is large, the lower half of the secondary air nozzle (1) remains unchanged while the upper half rotates in the opposite direction, the opening of the secondary air damper (5) decreases as a whole and gradually decreases from bottom to top, the burnout air nozzle (8) rotates in the opposite direction, and the opening of the burnout air damper (7) increases as a whole and gradually increases from bottom to top. When the boiler is operating in a state where the combustion tangent is biased towards angle A, the angle A of the secondary air nozzle (1) rotates in the opposite direction, the upstream adjacent angle of angle A rotates in the opposite direction, the downstream adjacent angle of angle A rotates in the positive direction and the downstream partition angle of angle A rotates in the positive direction, the opening of the secondary air damper (5) increases as a whole at angle A, decreases as a whole at the upstream adjacent angle of angle A, increases as a whole at the downstream adjacent angle of angle A and decreases as a whole at the downstream partition angle of angle A, the burnout air nozzle (8) does not rotate, and the opening of the burnout air damper (7) decreases as a whole; When the boiler is operating in a state where the combustion tangent is biased towards the left wall, the upper left corner of the secondary air nozzle (1) rotates in the opposite direction, the lower left corner rotates in the opposite direction, the upper right corner rotates in the forward direction and the lower right corner rotates in the opposite direction, the opening of the secondary air damper (5) increases as a whole at the upper left corner, increases as a whole at the lower left corner, decreases as a whole at the upper right corner and decreases as a whole at the lower right corner, the burnout air nozzle (8) does not rotate, and the opening of the burnout air damper (7) decreases as a whole.

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