A multi-channel rich-lean separated single-cone burner and its usage method

Abstract

The present invention relates to a multi-channel rich-lean separated single-cone burner and a method for using the same. The burner includes a pulverized coal supply mechanism, a transition channel, a multi-stage air distribution assembly, a deflector, a stable combustion chamber, and a rectification chamber. The multi-stage air distribution assembly includes N air guide cylinders, and the Nth air guide cylinder is sequentially connected to the stable combustion chamber and the rectification chamber. The pulverized coal supply mechanism includes a pulverized coal-air pipe and a rich-lean separator. The pulverized coal-air pipe is connected to the stable combustion chamber, and the rich-lean separator is detachably connected to the pulverized coal-air pipe. The transition channel is arranged at intervals inside the first air guide cylinder. The air guide cylinder is a double-layer hollow structure, and one end of at least one deflector is inserted into the corresponding air guide cylinder. At least one direct current channel is formed between each deflector and the stable combustion chamber, and a flared opening is formed at the other end of each deflector. The angle of the flared opening is the same as the angle of the stable combustion chamber. The present invention can divide the air into N streams and enter the burner body. The turbulence intensity at the air flow boundary is strong, which strengthens the mixing rate of pulverized coal and air, not only enables the pulverized coal to ignite stably, but also ensures the efficient and low-nitrogen combustion of the pulverized coal.

Description

Technical Field

[0001] The present invention relates to a pulverized coal burner, in particular to a multi-channel concentrated-dilute separated single-cone burner and its usage method, belonging to the technical field of efficient and clean utilization of coal. Background Art

[0002] Currently, in the field of pulverized coal industrial boilers, various burners such as blunt-body burners, swirl burners, and reverse-jet burners have emerged. Their common point is to use the high-temperature recirculation zone as an ignition source to ignite the pulverized coal air flow, achieving the purpose of efficient and low-nitrogen combustion of pulverized coal. However, the load adjustment range of the pulverized coal burner is narrow, and the coal type adaptability is poor; moreover, compared with chain boilers and circulating fluidized beds, pulverized coal industrial boilers also have the problem of high nitrogen oxides. Summary of the Invention

[0003] Aiming at the above problems, one of the purposes of the present invention is to provide a multi-channel concentrated-dilute separated single-cone burner with an extremely wide load adjustment range, strong coal type adaptability, and low nitrogen characteristics; another purpose of the present invention is to provide a usage method of the multi-channel concentrated-dilute separated single-cone burner.

[0004] To achieve the above purposes, the present invention adopts the following technical solutions: A multi-channel concentrated-dilute separated single-cone burner includes a pulverized coal supply mechanism, a transition channel, a multi-stage air distribution assembly, a deflector, a stable combustion chamber, and a rectification chamber; the multi-stage air distribution assembly includes N air guide cylinders coaxially arranged from the inside to the outside, and N is a natural number not less than 2; wherein, the Nth air guide cylinder is sequentially connected to the stable combustion chamber and the rectification chamber to form the burner body. The pulverized coal supply mechanism includes a wind-pulverized coal pipe and a concentrated-dilute separator. The wind-pulverized coal pipe is arranged on the central axis of the burner body and is connected to the stable combustion chamber. The concentrated-dilute separator is detachably connected to the wind-pulverized coal pipe for making the pulverized coal fed into the stable combustion chamber have a concentration distribution of inner-concentrated and outer-dilute or inner-dilute and outer-concentrated. The transition channel is arranged at intervals inside the first air guide cylinder, and thus N air inlet channels are formed between adjacent two air guide cylinders and between the first air guide cylinder and the transition channel; at the same time, except for the Nth air guide cylinder, the remaining air guide cylinders are all double-layer hollow structures, that is, an annular groove extending along the axial direction is arranged inside the remaining air guide cylinders, and one end of at least one deflector is inserted into the annular groove of the corresponding air guide cylinder to be fixed thereto; thus, at least one direct current channel is formed between each deflector and the stable combustion chamber, and an expansion port is formed at the other end of each deflector. The angle of the expansion port is the same as the angle of the stable combustion chamber, so that the outlet end direction of the direct current channel is parallel to the wall surface of the stable combustion chamber.

[0005] For the multi-channel lean-rich separation single-cone burner described above, preferably, the radial widths of the N air inlet channels are different, so as to select the corresponding air guide cylinder to insert into the deflector according to different coal types and loads.

[0006] For the multi-channel lean-rich separation single-cone burner described above, preferably, the number of the deflectors is controlled between 1 and 4, and when there are more than two deflectors, the length of the inner deflector should be less than that of the outer deflector.

[0007] For the multi-channel lean-rich separation single-cone burner described above, preferably, the lean-rich separator is a throat-type lean-rich separator, a gear-type lean-rich separator or a petal-shaped lean-rich separator, and external threads are formed on the outer wall of the lean-rich separator. At the same time, internal threads are formed on the inner wall of the outlet section of the air powder pipe. The lean-rich separator is inserted into the air powder pipe from the outlet end of the air powder pipe and is threadedly connected to the air powder pipe.

[0008] For the multi-channel lean-rich separation single-cone burner described above, preferably, the transition channel is a cylindrical structure with one end open and the other end closed. The air powder pipe is arranged axially in the transition channel. The outlet end of the air powder pipe penetrates through the closed end of the transition channel and is flush with it. An igniter and / or a flame detector are installed in the transition channel.

[0009] For the multi-channel lean-rich separation single-cone burner described above, preferably, the transition channel is a conical, elliptical or cylindrical blunt body, and the widest diameter of the transition channel should be less than the inner diameter of the first air guide cylinder, and the narrowest diameter should be greater than the maximum diameter of the igniter and / or the flame detector.

[0010] A method for using the above multi-channel lean-rich separation single-cone burner includes the following steps:

[0011] 1) Select the corresponding lean-rich separator according to the coal type and install it on the air powder pipe. At the same time, select the deflectors with appropriate lengths and quantities according to the coal type and insert them into the corresponding air guide cylinders. Mark the position of the innermost deflector as the mth air guide cylinder, and install axial impellers circumferentially in the first to mth air inlet channels;

[0012] 2) The air is divided into N strands by the staged air distribution assembly and enters the burner body. Among them, the first to mth strands of air form m rotating air beams with tangential velocity after passing through the axial impellers and enter the stable combustion chamber, and the m rotating air beams interact with each other to form a multi-layer nested high-temperature recirculation zone;

[0013] 3) Meanwhile, the pulverized coal air flow is injected into the stable combustion chamber through the pulverized coal pipe and the concentration separator. The pulverized coal presents a concentration distribution with a higher concentration in the inner part and a lower concentration in the outer part or vice versa in the stable combustion chamber. The pulverized coal is preheated to 900 - 1000 °C in the high-temperature recirculation zone, pyrolyzed in the low-oxygen and hot high-temperature recirculation zone, and mixed with multiple rotating air beams under the combined action in the transition channel to form a multi-layer main flame.

[0014] 4) The (m + 1)-th to N-th air inlet channels form straight-through channels. The (m + 1)-th to N-th air flows through each straight-through channel to form straight-through air beams with different speeds. This straight-through air beam has two functions: the first function is to form a cooling air layer flowing along the wall of the stable combustion chamber after passing through the flared opening of the deflector plate to cool the stable combustion chamber and the rectifying chamber; the second function is to form a high-speed jet multi-layer flame with the main flame passing through the rectifying chamber, where the air surrounds the flame, and enter the furnace.

[0015] In the described usage method, preferably, in step 1) above, if the coal type has a high volatile content and a high calorific value, then the concentration separator selects a throat-type concentration separator or a gear-type concentration separator; if the coal type has a low volatile content and a low calorific value, then the concentration separator selects a petal-shaped concentration separator.

[0016] In the described usage method, preferably, in step 1) above, if the coal type has a high volatile content and a high calorific value, then the length of the deflector plate is increased and / or the number of deflector plates is increased; if the coal type has a low volatile content and a low calorific value, then the length of the deflector plate is shortened and / or the number of deflector plates is decreased.

[0017] In the described usage method, preferably, the swirl number of the rotating air beam generated by the axial impeller should be controlled within the range of 0.6 - 2, and the wind speed of the straight-through air beam should be controlled within the range of 30 - 50 m / s.

[0018] Due to the adoption of the above technical solutions, the present invention has the following advantages: 1. The present invention adopts the design of a multi-stage air distribution component. Air enters the burner body through the multi-stage air distribution component and is divided into N strands. The turbulence intensity at the air flow boundary is strong, which enhances the air-powder mixing rate, not only enabling the pulverized coal to stably ignite, but also ensuring the high-efficiency and low-nitrogen combustion of the pulverized coal. 2. The multi-stage air distribution component of the present invention consists of a plurality of coaxial air guide cylinders arranged from the inside to the outside, and the air guide cylinders adopt a double-layer hollow structure. The deflector can be inserted into the double-layer hollow structure of any air guide cylinder, thereby forming a multi-layer flame structure with a stable combustion cavity and a wall of the rectifying cavity having attached wall cooling air. The combustion-supporting air slowly penetrates into the main flame, ensuring that the environment in the middle of the main flame is high-temperature, high-CO, and low-oxygen, prolonging the residence time of the pulverized coal in the high-temperature and reducing atmosphere, and achieving the purpose of high combustion efficiency and low nitrogen. At the same time, the direct current air beam formed between the deflector and the stable combustion cavity can form a cooling air layer flowing along the wall of the stable combustion cavity in the stable combustion cavity to cool the stable combustion cavity and the rectifying cavity, so that the wall temperature of the stable combustion cavity and the rectifying cavity is always lower than 40 °C. This not only can cancel the water cooling device of the stable combustion cavity but also avoids the occurrence of ash fouling and coking on the wall of the stable combustion cavity. 3. The present invention can mechanically control the mixing rate of the combustion-supporting air and the main flame by adjusting the length and quantity of the deflector. The load adjustment range is 10% - 110%, with an extremely wide load adjustment range. In addition, it also has the characteristics of wide coal type adaptability, good stable combustion, and low nitrogen. 4. The present invention also adopts a transition channel design. This transition channel can not only be internally provided with an ignition oil gun and an igniter, but also the transition channel and the internal secondary air channel with a movable axial impeller inside can jointly generate a recirculation zone with a high turbulence intensity, enhancing the mixing rate of the pulverized coal and air and improving the burnout rate of the pulverized coal under low-load conditions. 5. The pulverized coal of the present invention enters the burner through a concentration-difference separator. The concentration-difference separator makes the pulverized coal have an inner-concentrated and outer-dilute pulverized coal concentration distribution. The flame is not easily dispersed, the flame rigidity is enhanced, and under the combined action of the inner and outer secondary air, the stable combustion cavity, and the rectifying cavity, the flame length can be increased, which helps to improve the combustion efficiency and reduce nitrogen oxides. The present invention is suitable for the opposed arrangement and tangential firing arrangement of multiple burners. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a three-dimensional longitudinal sectional structure schematic diagram of the multi-channel concentration-difference separation type single-cone burner of the present invention;

[0020] Figure 2 is a two-dimensional longitudinal sectional structure schematic diagram of the multi-channel concentration-difference separation type single-cone burner of the present invention;

[0021] Figure 3 is a structure schematic diagram of a throat-type concentration-difference separator;

[0022] Figure 4 is a structure schematic diagram of a gear-type concentration-difference separator;

[0023] Figure 5It is a schematic structural diagram of a petal-shaped concentration separator;

[0024] Figure 6 It is a schematic diagram of the internal flow field of the multi-channel concentration separation single-cone burner of the present invention. Specific embodiments

[0025] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. At the same time, in the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the protection scope of the present invention.

[0027] As Figure 1 、 Figure 2 shown, the multi-channel concentration separation single-cone burner provided by the present invention includes a pulverized coal supply mechanism 1, a transition channel 2, a multi-stage air distribution assembly 3, a deflector 4, a stable combustion chamber 5, and a rectifying chamber 6. The multi-stage air distribution assembly 3 includes N air guiding cylinders arranged coaxially from the inside to the outside (N is a natural number not less than 2), wherein the Nth (i.e., the outermost) air guiding cylinder is sequentially connected to the stable combustion chamber 5 and the rectifying chamber 6 to form a burner body. The pulverized coal supply mechanism 1 includes a pulverized coal-air pipe 11 and a concentration separator 12. The pulverized coal-air pipe 11 is arranged on the central axis of the burner body and is communicated with the stable combustion chamber 5. The concentration separator 12 is detachably connected to the pulverized coal-air pipe 11 and is used to make the pulverized coal fed into the stable combustion chamber 5 have an inner-concentrated and outer-dilute or inner-dilute and outer-concentrated concentration distribution. The transition channel 2 is arranged at intervals inside the first (i.e., the innermost) air guiding cylinder, and thus a total of N air inlet channels are formed between adjacent two air guiding cylinders and between the first air guiding cylinder and the transition channel 2. At the same time, except for the Nth air guiding cylinder, the remaining air guiding cylinders are all double-layer hollow structures, that is, annular grooves extending along the axial direction are arranged inside the remaining air guiding cylinders, and one end of at least one deflector 4 can be inserted into the annular groove of the corresponding air guiding cylinder to be fixed thereto. Thus, at least one direct current channel is formed between each deflector 4 and the stable combustion chamber 5, and an expansion port is formed at the other end of each deflector 4, and the angle of the expansion port is the same as the angle of the stable combustion chamber 5, so that the outlet end direction of the direct current channel is parallel to the wall surface of the stable combustion chamber 5.

[0028] In the above embodiments, preferably, the radial widths of the N air inlet channels are different from each other. Thus, the corresponding air guide cylinder can be inserted into the flow guide plate 4 according to different coal types and loads to control the mixing rate of air and the main flame, adjust the high-temperature recirculation zone, and thereby broaden the load adjustment range and coal type adaptability of the burner.

[0029] In the above embodiments, preferably, the number of the flow guide plates 4 is controlled between 1 and 4. When there are more than two flow guide plates 4, the length of the inner flow guide plate 4 should be less than that of the outer flow guide plate 4.

[0030] In the above embodiments, preferably, the lean / rich separator 12 can be a throat-type lean / rich separator (as shown in Figure 3 ), a gear-type lean / rich separator (as shown in Figure 4 ), or a petal-shaped lean / rich separator (as shown in Figure 5 ). An external thread is formed on the outer wall of the lean / rich separator 12, and at the same time, an internal thread is formed on the inner wall of the outlet section of the pulverized coal-air pipe 11. The lean / rich separator 12 can be inserted into the pulverized coal-air pipe 11 from the outlet end of the pulverized coal-air pipe 11 and is threadedly connected to the pulverized coal-air pipe 11. Thus, the corresponding lean / rich separator 12 can be replaced according to the coal type to broaden the load adjustment range and coal type adaptability of the burner.

[0031] In the above embodiments, preferably, the transition channel 2 is a cylindrical structure with one end open and the other end closed. The pulverized coal-air pipe 11 is axially arranged in the transition channel 2, and the outlet end of the pulverized coal-air pipe 11 penetrates through the closed end of the transition channel 2 and is flush with it. An igniter and / or a flame detector (not shown in the figure) can be installed in the transition channel 2.

[0032] In the above embodiments, preferably, the transition channel 2 is a conical, elliptical, cylindrical or any other arbitrary curve blunt body, and the widest diameter of the transition channel 2 should be less than the inner diameter of the first air guide cylinder, and the narrowest diameter should be greater than the maximum diameter of the igniter and / or the flame detector.

[0033] As shown in Figure 6 , based on the multi-channel lean / rich separation single-cone burner provided in the above embodiments, the present invention also proposes a use method of the multi-channel lean / rich separation single-cone burner, including the following steps:

[0034] 1) Select the corresponding lean / rich separator 12 according to the coal type and install it on the pulverized coal-air pipe 11. At the same time, select the flow guide plates 4 with appropriate lengths and quantities according to the coal type and insert them into the corresponding air guide cylinders. Denote the position of the innermost flow guide plate 4 as the mth air guide cylinder, and axially install axial impellers (not shown in the figure) circumferentially in the first to mth air inlet channels;

[0035] 2) The air is divided into N strands by the staged air distribution component 3 and enters the burner body. Among them, the first to m strands of air form m rotating air beams with tangential velocity after passing through the axial impeller and enter the stable combustion chamber 5. And the m rotating air beams interact with each other to form a multi-layer nested high-temperature recirculation zone;

[0036] 3) At the same time, the pulverized coal air flow is sprayed into the stable combustion chamber 5 through the pulverized coal pipe 11 and the lean-rich separator 12. The pulverized coal presents a concentration distribution of rich inside and lean outside or lean inside and rich outside in the stable combustion chamber 5. The pulverized coal is preheated to 900 - 1000 °C in the high-temperature recirculation zone. The pulverized coal pyrolyzes in the low-oxygen and hot high-temperature recirculation zone and is mixed with multiple rotating air beams under the combined action in the transition channel 2 to form a multi-layer main flame;

[0037] 4) The (m + 1)-th to N-th air inlet channels form straight-through channels. The (m + 1)-th to N-th strands of air form straight-through air beams with different velocities (the air velocity decreases sequentially from outside to inside) after passing through each straight-through channel. This straight-through air beam has two functions: The first function is to form a cooling air layer flowing along the wall of the stable combustion chamber 5 after passing through the flared opening of the deflector 4 to cool the stable combustion chamber 5 and the rectifying chamber 6, so that the wall temperatures of the stable combustion chamber 5 and the rectifying chamber 6 are lower than 40 °C; The second function is to form a high-speed jet multi-layer flame of air wrapping fire with the main flame through the rectifying chamber 6 and enter the furnace. Thereby, not only the pulverized coal burns stably, but also the occurrence of ash deposition and coking in the burner body and the furnace is avoided.

[0038] In the above embodiments, preferably, in the above step 1), if the coal type has high volatile matter and high calorific value, the lean-rich separator 12 selects a throat-type lean-rich separator or a gear-type lean-rich separator. Thereby, a concentration distribution of rich inside and lean outside of the pulverized coal can be generated, the rigidity of the main flame is enhanced, and thus the flame length of the main flame is increased, which is beneficial to improving the combustion efficiency and reducing the nitrogen oxide emission; if the coal type has low volatile matter and low calorific value, the lean-rich separator 12 selects a petal-shaped lean-rich separator, which can not only generate a concentration distribution of rich outside and lean inside of the pulverized coal, but also form several small high-temperature flue gas recirculation zones near the outlet of the petal-shaped lean-rich separator, which helps the ignition and stable combustion of the pulverized coal.

[0039] In the above embodiments, preferably, in the above step 1), if the coal type has a high volatile content and a high calorific value, the length of the deflector 4 can be increased and / or the number of deflectors 4 can be increased, thereby delaying the mixing time of the combustion-supporting air (including the swirling air beam and the direct current air beam) and the main flame, enhancing the reducing atmosphere in the main flame, and being beneficial to reducing nitrogen oxides; if the coal type has a low volatile content and a low calorific value, the length of the deflector 4 can be shortened and / or the number of deflectors 4 can be reduced (even the deflector 4 can be cancelled), thereby strengthening the mixing of the combustion-supporting air and the main flame, being beneficial to the ignition of pulverized coal, and enabling the stable combustion of pulverized coal. Thus, it can be seen that by adjusting the length and number of the deflector 4, the mixing rate of air and the main flame can be mechanically controlled, and the load adjustment range can reach 10% - 110%.

[0040] In the above embodiments, preferably, the swirl number of the swirling air beam generated by the axial impeller should be controlled within the range of 0.6 - 2.

[0041] In the above embodiments, preferably, the wind speed of the direct current air beam should be controlled within the range of 30 - 50 m / s.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-channel lean-rich separated single-cone burner, characterized in that, It includes a pulverized coal supply mechanism (1), a transition passage (2), a multi-stage air distribution assembly (3), a deflector (4), a stable combustion chamber (5) and a rectifying chamber (6); The multi-stage air distribution assembly (3) includes N air guiding cylinders coaxially arranged from inside to outside, and N is a natural number not less than 2; among them, the Nth air guiding cylinder is sequentially connected to the stable combustion chamber (5) and the rectifying chamber (6) to form a burner body. The pulverized coal supply mechanism (1) includes a pulverized coal-air pipe (11) and a concentration separator (12). The pulverized coal-air pipe (11) is arranged on the central axis of the burner body and is communicated with the stable combustion chamber (5). The concentration separator (12) is detachably connected to the pulverized coal-air pipe (11) and is used to make the pulverized coal fed into the stable combustion chamber (5) have an inner-concentrated and outer-dilute or inner-dilute and outer-concentrated concentration distribution. The transition passage (2) is arranged at intervals inside the first air guiding cylinder, and thus a total of N air inlet passages are formed between adjacent two air guiding cylinders and between the first air guiding cylinder and the transition passage (2); At the same time, except for the Nth air guiding cylinder, the rest of the air guiding cylinders are all double-layer hollow structures, that is, an annular groove extending along the axial direction is arranged inside the rest of the air guiding cylinders, and one end of at least one deflector (4) is inserted into the annular groove of the corresponding air guiding cylinder to be fixed thereto; Thus, at least one direct current passage is formed between each deflector (4) and the stable combustion chamber (5), and one end of each deflector (4) is formed with a flared opening, and the angle of the flared opening is the same as the angle of the stable combustion chamber (5), so that the outlet end direction of the direct current passage is parallel to the wall surface of the stable combustion chamber (5); The transition passage (2) is a cylindrical structure with one end open and the other end closed. The pulverized coal-air pipe (11) is arranged axially inside the transition passage (2), and the outlet end of the pulverized coal-air pipe (11) penetrates through the closed end of the transition passage (2) and is flush with it.

2. The multi-channel rich-lean separated single-cone burner according to claim 1, characterized in that The radial widths of the N air inlet passages are different from each other, so as to select the corresponding air guiding cylinder to insert the deflector (4) according to different coal types and loads.

3. The multi-channel rich-lean separated single-cone burner according to claim 1, characterized in that, The number of the deflectors (4) is controlled between 1 and 4, and when there are more than two deflectors (4), the length of the deflector (4) located inside is less than the length of the deflector (4) located outside.

4. The multi-channel lean-rich separated single-cone burner according to claim 1, wherein The concentration separator (12) is a throat-type concentration separator, a gear-type concentration separator or a petal-type concentration separator, and an external thread is formed on the outer wall of the concentration separator (12). At the same time, an internal thread is formed on the inner wall of the outlet section of the pulverized coal-air pipe (11). The concentration separator (12) is inserted into the pulverized coal-air pipe (11) from the outlet end of the pulverized coal-air pipe (11) and is threadedly connected to the pulverized coal-air pipe (11).

5. The multi-channel lean-rich separated single-cone burner according to claim 4, wherein, An igniter and / or a flame detector are installed inside the transition passage (2).

6. The multi-channel lean-rich separation single-cone burner according to claim 5, characterized in that The transition passage (2) is a conical, elliptical or cylindrical blunt body, and the widest diameter of the transition passage (2) should be less than the inner diameter of the first air guiding cylinder, and the narrowest diameter should be greater than the maximum diameter of the igniter and / or the flame detector.

7. A method for using a multi-channel lean-rich separation single-cone burner according to any one of claims 1 to 6, characterized in that, It includes the following steps: 1) Select the corresponding concentration-dilution separator (12) according to the coal type and install it on the pulverized coal-air pipe (11). At the same time, select the deflectors (4) with appropriate length and quantity according to the coal type and insert them into the corresponding air guide tubes. Denote the position of the innermost deflector (4) as the m-th air guide tube, and install axial impellers circumferentially in the 1st to m-th air inlet channels; 2) The air is divided into N strands by the classified air distribution assembly (3) and enters the burner body. Among them, the 1st to m-th strands of air form m swirling air beams with tangential velocity after passing through the axial impellers and enter the stable combustion chamber (5). And the m swirling air beams interact with each other to form a multi-layer nested high-temperature recirculation zone; 3) At the same time, the pulverized coal air flow is injected into the stable combustion chamber (5) through the pulverized coal-air pipe (11) and the concentration-dilution separator (12). The pulverized coal shows a concentration distribution of thick in the inner and thin in the outer or thin in the inner and thick in the outer in the stable combustion chamber (5). The pulverized coal is preheated to 900 - 1000 °C in the high-temperature recirculation zone. The pulverized coal pyrolyzes in the low-oxygen and scorching high-temperature recirculation zone, and is mixed with multiple swirling air beams under the joint action in the transition channel (2) to form a multi-layer main flame; 4) The (m + 1)-th to N-th air inlet channels form straight-through channels. The (m + 1)-th to N-th strands of air form straight-through air beams with different velocities after passing through the respective straight-through channels. This straight-through air beam has two functions: the first function is to form a cooling air layer flowing along the wall of the stable combustion chamber (5) after passing through the flared opening of the deflector (4) to cool the stable combustion chamber (5) and the rectifying chamber (6); the second function is to form a high-speed jet multi-layer flame of wind surrounding fire with the main flame through the rectifying chamber (6) and enter the furnace.

8. The usage method according to claim 7, characterized in that, In step 1) above, if it is a coal type with high volatile matter and high calorific value, then the concentration-dilution separator (12) selects a throat-type concentration-dilution separator or a gear-type concentration-dilution separator; If it is a coal type with low volatile matter and low calorific value, then the concentration-dilution separator (12) selects a petal-shaped concentration-dilution separator.

9. The usage method according to claim 7, characterized in that, In step 1) above, if it is a coal type with high volatile matter and high calorific value, then lengthen the length of the deflector (4) and / or increase the quantity of the deflector (4); If it is a coal type with low volatile matter and low calorific value, then shorten the length of the deflector (4) and / or reduce the quantity of the deflector (4).

10. The usage method according to claim 7, characterized in that The swirl number of the swirling air beam generated by the axial impeller should be controlled within the range of 0.6 - 2, and the wind speed of the straight-through air beam should be controlled within the range of 30 - 50 m / s.

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