A dual-channel reverse-jet swirl burner and its use method

Abstract

The present invention relates to a dual-channel reverse jet swirl burner and a method for using the same. The burner includes a pulverized coal supply mechanism, a transition channel, an inner / outer secondary air guide, a combustion stabilization chamber, and a rectifying chamber. The outer secondary air guide, the combustion stabilization chamber, and the rectifying chamber are sequentially connected to form a burner body. The pulverized coal supply mechanism runs through the burner body, and the transition channel is sleeved on the pulverized coal supply mechanism. The inner secondary air guide is arranged between the transition channel and the outer secondary air guide, and forms an inner secondary air channel with the transition channel, and forms an outer secondary air channel with the outer secondary air guide. An expansion port is formed at the outlet end of the inner secondary air guide, and the expansion port angle is the same as the expansion port angle of the combustion stabilization chamber. The present invention can separate air into inner and outer secondary air and enter the burner respectively. The inner secondary air is combined with the transition channel to fully mix the pulverized coal and the air. The outer secondary air can form a cooling air layer in the combustion stabilization chamber that flows along the combustion stabilization chamber wall surface, thereby avoiding the occurrence of ash and coking on the combustion stabilization chamber wall surface.

Description

Technical Field

[0001] The invention relates to a pulverized coal burner, in particular to a dual-channel reverse-jet swirl burner and a use method thereof, belonging to the technical field of efficient and clean utilization of coal. Background Art

[0002] At present, in the field of pulverized coal industrial boilers, there are many types of burners such as blunt body burners, swirl burners and reverse jet burners. Their common point is to use the high-temperature recirculation zone as the ignition source to ignite the pulverized coal airflow to achieve the purpose of high-efficiency and low-nitrogen combustion of pulverized coal. However, due to the intense combustion of pulverized coal inside the burner, the temperature inside the burner can reach above 1100°C, and the burner is in the high-temperature combustion zone for a long time, so there is a phenomenon of high-temperature thermal corrosion; and compared with chain furnaces and circulating fluidized beds, pulverized coal industrial boilers have a narrow load adjustment range and are prone to low burnout rate during low-load operation. Summary of the invention

[0003] In response to the above problems, one of the objects of the present invention is to provide a dual-channel reverse-jet swirl burner with the characteristics of wide load regulation range, stable combustion and low nitrogen; another object of the present invention is to provide a method for using the dual-channel reverse-jet swirl burner.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a dual-channel reverse-jet swirl burner, comprising a coal powder supply mechanism, a transition channel, an inner secondary air guide tube, an outer secondary air guide tube, a combustion stabilization chamber and a rectification chamber; wherein the outer secondary air guide tube, the combustion stabilization chamber and the rectification chamber are connected in sequence to form a burner body, the coal powder supply mechanism runs through the inside of the burner body, and the transition channel is sleeved on the outside of the inlet end of the coal powder supply mechanism; the inner secondary air guide tube is arranged between the transition channel and the outer secondary air guide tube, an inner secondary air channel is formed between the inner secondary air guide tube and the transition channel, and an outer secondary air channel is formed between the inner secondary air guide tube and the outer secondary air guide tube; at the same time, a flared opening is formed at the outlet end of the inner secondary air guide tube, and the angle of the flared opening is the same as the angle of the combustion stabilization chamber, thereby making the outlet end direction of the inner secondary air channel parallel to the wall surface of the combustion stabilization chamber.

[0005] The dual-channel reverse-jet swirl burner is preferably provided with a movable axial impeller assembly in the inner secondary air channel, so as to form a rotating airflow with a tangential velocity after the inner secondary air passes through the movable axial impeller assembly.

[0006] The dual-channel reverse-jet swirl burner preferably has the movable axial impeller assembly comprising: an axial impeller, which is circumferentially arranged in the inner secondary air channel and movable axially; an adjustable telescopic pull rod, one end of which is connected to the axial impeller via a first hinge pair; and a locking pull rod, which is connected to the other end of the adjustable telescopic pull rod via a second hinge pair.

[0007] In the dual-channel reverse-jet swirl burner, preferably, the inner secondary air guide tube and the outer secondary air guide tube are connected by a plurality of movable positioning components distributed along the circumferential direction, and the movable positioning components are used to adjust the cross-sectional area of ​​the outer secondary channel.

[0008] The dual-channel reverse-jet swirl burner preferably has a plurality of threaded holes circumferentially provided on the inner secondary air guide tube, a plurality of light holes circumferentially provided on the outer secondary air guide tube, and the outer secondary air guide tube has a flexible tube wall; at the same time, the movable positioning assembly is mainly composed of an adjusting bolt and a sealing gasket, and the adjusting bolt passes through the sealing gasket and the light hole of the outer secondary air guide tube and is threadedly connected with the threaded hole of the inner secondary air guide tube.

[0009] The dual-channel reverse-jet swirl burner preferably has the coal powder supply mechanism mainly composed of an air-powder pipe and a reflux cap, the air-powder pipe is placed on the central axis of the burner body, the reflux cap is arranged at the outlet end of the air-powder pipe and located at the outlet section of the stable combustion chamber, and a plurality of through holes are opened on the stable combustion chamber.

[0010] The dual-channel reverse-jet swirl burner preferably has a transition channel that is a cylindrical structure with one end open and the other end closed, and the air-powder tube extends into the interior of the burner body after passing through the closed end of the transition channel, and an igniter and / or flame detector is installed in the transition channel; the transition channel is a conical, elliptical or cylindrical blunt body, and the widest diameter of the transition channel should be smaller than the inner diameter of the inner secondary air guide cylinder, and the narrowest diameter should be larger than the maximum diameter of the igniter and / or flame detector.

[0011] A method for using the above-mentioned dual-channel reverse-jet swirl burner comprises the following steps:

[0012] 1) The air enters the burner body in two ways. One of the air passes through the movable axial impeller assembly and the inner secondary air channel to form a rotating inner secondary air with a tangential velocity and directly enters the stable combustion chamber. The inner secondary air channel and the transition channel work together to form a nested high-temperature reflow zone;

[0013] 2) At the same time, the coal powder airflow enters the high-temperature recirculation zone through the recirculation channel composed of the air-powder pipe and the recirculation cap. The coal powder presents a concentration distribution of thick outside and thin inside. The coal powder is preheated to 900-1000℃ in the high-temperature recirculation zone. The coal powder is pyrolyzed in the low-oxygen and hot high-temperature recirculation zone, and is mixed with the internal secondary air at the closed end of the transition channel to form the main flame. The coal powder airflow swirls and burns in the burner body;

[0014] 3) Another path of the air passes through the external secondary air channel to form external secondary air. A part of the external secondary air passes through the expansion of the external secondary air guide tube to form a cooling air layer flowing along the wall of the stable combustion chamber to cool the stable combustion chamber and the rectifying chamber, so that the wall temperature of the stable combustion chamber and the rectifying chamber is lower than 40°C; the other part of the external secondary air forms a high-speed jet flame with wind enveloping fire with the main flame through the rectifying chamber and enters the furnace.

[0015] In the method of use, preferably, the swirl number of the rotating airflow generated by the movable axial impeller assembly should be controlled within the range of 0 to 2, the wind speed of the external secondary air should be controlled within the range of 20 to 50 m / s, and the ratio of the internal secondary air to the external secondary air is preferably 1:2.

[0016] The method of use is preferably such that in the above step 3), the cross-sectional area of ​​the outer secondary air channel is adjusted by the movable positioning assembly, thereby adjusting the wind speed of the outer secondary air and controlling the mixing rate of the inner secondary air and the outer secondary air.

[0017] Due to the above technical scheme adopted in the present invention, it has the following advantages: 1. The present invention is provided with an inner secondary air duct and an outer secondary air duct, so that the air can be divided into inner secondary air and outer secondary air and enter the burner body respectively, which not only makes the air enter the burner in stages to reduce nitrogen oxides, the inner secondary air is combined with the transition channel to make the coal powder and air fully mixed and stably burned, and the outer secondary air can form a cooling air layer in the stable combustion chamber that flows along the wall of the stable combustion chamber to cool the stable combustion chamber and the rectifying chamber, so that the wall temperature of the stable combustion chamber and the rectifying chamber is always lower than 40°C, which not only can eliminate the water cooling device of the stable combustion chamber, but also avoid the occurrence of ash and coking on the wall of the stable combustion chamber. 2. The present invention can adjust the cross-sectional area of ​​the external secondary air channel through a movable positioning component, thereby adjusting the wind speed of the external secondary air, controlling the mixing rate of the internal secondary air and the external secondary air, and thus controlling the combustion process of the coal powder airflow in the burner body, thereby forming an internal low-oxygen, high-temperature, external high-oxygen, low-temperature environment in the stable combustion chamber. This temperature distribution and atmosphere distribution can not only achieve the effect of high combustion efficiency and low nitrogen, broaden the load adjustment range and coal type adaptability of the burner, but also effectively solve the high-temperature corrosion, ash accumulation and coking of the stable combustion chamber wall, reduce the maintenance frequency of the burner, and extend the service life of the burner. 3. The present invention also adopts the design of a transition channel, which can not only have an ignition oil gun and an igniter built in, but also the transition channel can work together with the internal secondary air channel with a built-in movable axial impeller to produce a high turbulence intensity recirculation zone, enhance the mixing rate of coal powder and air, and improve the burnout rate of coal powder under low load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional longitudinal section structure of the dual-channel reverse-jet swirl burner of the present invention;

[0019] Figure 2 It is a structural schematic diagram of the movable axial impeller assembly of the present invention;

[0020] Figure 3 It is a structural schematic diagram of the movable positioning assembly of the present invention;

[0021] Figure 4 It is a schematic diagram of the internal flow field of the dual-channel reverse-jet swirl burner of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution 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, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. At the same time, in the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the directions 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0024] like Figure 1 As shown, the dual-channel reverse-jet swirl burner provided by the present invention comprises a pulverized coal supply mechanism 1, a transition channel 2, an inner secondary air guide 3, an outer secondary air guide 4, a combustion stabilizing chamber 5 and a rectifying chamber 6. Among them, the outer secondary air guide 4, the combustion stabilizing chamber 5 and the rectifying chamber 6 are sequentially connected to form a burner body, the pulverized coal supply mechanism 1 runs through the inside of the burner body, and the transition channel 2 is sleeved outside the inlet end of the pulverized coal supply mechanism 1. The inner secondary air guide 3 is arranged between the transition channel 2 and the outer secondary air guide 4, and an inner secondary air channel is formed between the inner secondary air guide 3 and the transition channel 2, and an outer secondary air channel is formed between the inner secondary air guide 3 and the outer secondary air guide 4. At the same time, a flared port is formed at the outlet end of the inner secondary air guide 3, and the angle of the flared port is the same as that of the combustion stabilizing chamber 5, thereby making the outlet end direction of the inner secondary air channel parallel to the wall surface of the combustion stabilizing chamber 5.

[0025] In the above embodiment, preferably, Figure 2 As shown, a movable axial impeller assembly 7 is provided in the inner secondary air channel, so as to make the inner secondary air form a rotating airflow with a tangential velocity after passing through the movable axial impeller assembly 7 .

[0026] In the above embodiment, preferably, the movable axial impeller assembly 7 comprises: an axial impeller 71, which is circumferentially arranged in the inner secondary air channel and can move axially; an adjustable telescopic pull rod 72, one end of which is connected to the axial impeller 71 through a first hinge pair; and a locking pull rod 73, which is connected to the other end of the adjustable telescopic pull rod 72 through a second hinge pair. Thus, the axial impeller 71 can be moved axially to enter and exit the inner secondary air channel by pushing and pulling the locking pull rod 73, and the hinge pair can ensure smooth movement of the axial impeller 71.

[0027] In the above embodiment, preferably, Figure 3 As shown, the inner secondary air guide cylinder 3 and the outer secondary air guide cylinder 4 are connected by a plurality of movable positioning components 8 distributed along the circumferential direction, and the movable positioning components 8 are used to adjust the cross-sectional area of ​​the outer secondary channel.

[0028] In the above embodiment, preferably, a plurality of threaded holes 31 are opened on the inner secondary air guide tube 3 along the circumference, a plurality of light holes 41 are opened on the outer secondary air guide tube 4 along the circumference, and the outer secondary air guide tube 4 is a flexible tube wall; meanwhile, the movable positioning assembly 8 is mainly composed of an adjusting bolt 81 and a sealing gasket 82, and the adjusting bolt 81 passes through the sealing gasket 82 and the light hole 41 of the outer secondary air guide tube 4 and is threadedly connected with the threaded hole 31 of the inner secondary air guide tube 3. Thus, by screwing in or out the adjusting bolt 81, the tube wall of the outer secondary air guide tube 4 is deformed, thereby adjusting the cross-sectional area of ​​the outer secondary channel.

[0029] In the above embodiment, preferably, Figure 1 As shown, the pulverized coal supply mechanism 1 is mainly composed of an air-powder pipe 11 and a reflux cap 12 . The air-powder pipe 11 is placed on the central axis of the burner body, and the reflux cap 12 is arranged at the outlet end of the air-powder pipe 11 and located at the outlet section of the stable combustion chamber 5 .

[0030] In the above embodiment, preferably, the transition channel 2 is a cylindrical structure with one end open and the other end closed, and the air powder tube 11 passes through the closed end of the transition channel 2 and extends into the interior of the burner body. An igniter and / or a flame detector (not shown in the figure) can be installed in the transition channel 2.

[0031] In the above embodiments, preferably, the transition channel 2 is conical, elliptical, cylindrical or any other curved blunt body, and the widest diameter of the transition channel 2 should be smaller than the inner diameter of the inner secondary air guide cylinder 3, and the narrowest diameter should be larger than the maximum diameter of the igniter and / or flame detector.

[0032] In the above embodiment, preferably, a plurality of through holes (not shown in the figure) may be opened on the combustion stabilization chamber 5 to prevent the combustion stabilization chamber 5 from being deformed due to overheating of the combustion stabilization chamber 5 caused by unexpected factors.

[0033] Based on the dual-channel reverse-jet swirl burner provided in the above embodiment, the present invention also provides a method for using the dual-channel reverse-jet swirl burner, comprising the following steps:

[0034] 1) If Figure 4 As shown, the air enters the burner body in two ways. One of the air passes through the movable axial impeller assembly 7 and the inner secondary air channel to form a rotating inner secondary air with a tangential velocity and directly enters the stable combustion chamber 5. The inner secondary air channel and the transition channel 2 work together to form a nested high-temperature reflow zone.

[0035] 2) At the same time, the coal powder airflow enters the high-temperature recirculation zone through the recirculation channel composed of the air-powder pipe 11 and the recirculation cap 12. The coal powder presents a concentration distribution of thick outside and thin inside. The coal powder is preheated to 900-1000°C in the high-temperature recirculation zone. The coal powder is pyrolyzed in the low-oxygen and hot high-temperature recirculation zone and mixed with the internal secondary air at the closed end of the transition channel 2 to form a main flame. The coal powder airflow swirls and burns in the burner body.

[0036] 3) Another path of the air passes through the external secondary air channel to form external secondary air. A part of the external secondary air passes through the expansion of the external secondary air guide tube 4 to form a cooling air layer flowing along the wall of the stable combustion chamber 5, so as to cool the stable combustion chamber 5 and the rectifying chamber 6, so that the wall temperature of the stable combustion chamber 5 and the rectifying chamber 6 is lower than 40°C; another part of the external secondary air forms a high-speed jet flame of wind-wrapped fire with the main flame through the rectifying chamber 6 and enters the furnace, thereby not only stably burning the coal powder, but also avoiding the occurrence of ash and coking in the burner body and the furnace.

[0037] In the above embodiment, preferably, in the above step 1), the swirl number of the rotating airflow generated by the movable axial impeller assembly 7 should be controlled within the range of 0-2.

[0038] In the above embodiment, preferably, in the above step 3), the cross-sectional area of ​​the external secondary air channel can be adjusted by the movable positioning assembly 8, thereby adjusting the wind speed of the external secondary air, controlling the mixing rate of the internal secondary air and the external secondary air, and thus controlling the combustion process of the pulverized coal airflow in the burner body, thereby forming an internal low-oxygen, high-temperature and external high-oxygen, low-temperature environment in the stable combustion chamber 5, which not only has the effects of high efficiency and low nitrogen, but also can effectively avoid the occurrence of ash accumulation and coking in the burner body and the furnace.

[0039] In the above embodiments, preferably, the wind speed of the external secondary air should be controlled within the range of 20 to 50 m / s.

[0040] In the above embodiment, preferably, the ratio of the inner secondary air to the outer secondary air is preferably 1:2. This ratio can not only ensure the stable combustion of the coal powder, so that the inner secondary air is mixed with the main flame layer by layer to reduce nitrogen oxides, but also enable the outer secondary air attached to the wall to have sufficient momentum to cool the stabilizing combustion chamber 5 and the rectifying chamber 6.

[0041] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the above components. Unless otherwise stated, the above terms have no special meanings and therefore cannot be understood as limiting the scope of protection of the present invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-channel reverse jet swirl burner, characterized in that: It comprises a pulverized coal supply mechanism (1), a transition channel (2), an inner secondary air guide tube (3), an outer secondary air guide tube (4), a combustion stabilization chamber (5) and a rectification chamber (6); The external secondary air guide cylinder (4), the combustion stabilization chamber (5) and the rectifying chamber (6) are connected in sequence to form a burner body, the pulverized coal supply mechanism (1) runs through the inside of the burner body, and the transition channel (2) is sleeved outside the inlet end of the pulverized coal supply mechanism (1); The inner secondary air guide tube (3) is arranged between the transition channel (2) and the outer secondary air guide tube (4); an inner secondary air channel is formed between the inner secondary air guide tube (3) and the transition channel (2); and an outer secondary air channel is formed between the inner secondary air guide tube (3) and the outer secondary air guide tube (4); At the same time, a flared opening is formed at the outlet end of the inner secondary air guide tube (3), and the angle of the flared opening is the same as the angle of the combustion stabilization chamber (5), thereby making the outlet end direction of the inner secondary air channel parallel to the wall surface of the combustion stabilization chamber (5); The inner secondary air guide cylinder (3) and the outer secondary air guide cylinder (4) are connected via a plurality of movable positioning components (8) distributed along the circumferential direction, wherein the movable positioning components (8) are used to adjust the cross-sectional area of ​​the outer secondary air channel; The inner secondary air guide tube (3) is provided with a plurality of threaded holes (31) along the circumferential direction, the outer secondary air guide tube (4) is provided with a plurality of light holes (41) along the circumferential direction, and the outer secondary air guide tube (4) is a flexible tube wall; At the same time, the movable positioning assembly (8) is mainly composed of an adjusting bolt (81) and a sealing gasket (82); the adjusting bolt (81) passes through the sealing gasket (82) and the light hole (41) of the outer secondary air guide tube (4) and is threadedly connected to the threaded hole (31) of the inner secondary air guide tube (3).

2. The dual-channel reverse-jet swirl burner according to claim 1, characterized in that: A movable axial impeller assembly (7) is provided in the inner secondary air channel, and is used to allow the inner secondary air to pass through the movable axial impeller assembly (7) to form a rotating airflow with a tangential velocity.

3. The dual-channel reverse-jet swirl burner according to claim 2 is characterized in that: The movable axial impeller assembly (7) comprises: An axial impeller (71) is circumferentially arranged in the inner secondary air channel and is movable in the axial direction; An adjustable telescopic pull rod (72), one end of the adjustable telescopic pull rod (72) being connected to the axial impeller (71) via a first hinge pair; The locking pull rod (73) is connected to the other end of the adjustable telescopic pull rod (72) via a second hinge pair.

4. The dual-channel reverse-jet swirl burner according to claim 1, characterized in that: The pulverized coal supply mechanism (1) is mainly composed of an air-powder pipe (11) and a return cap (12); the air-powder pipe (11) is placed on the central axis of the burner body; the return cap (12) is arranged at the outlet end of the air-powder pipe (11) and located at the outlet section of the combustion stabilization chamber (5); and a plurality of through holes are opened on the combustion stabilization chamber (5).

5. The dual-channel reverse-jet swirl burner according to claim 4 is characterized in that: The transition channel (2) is a cylindrical structure with one end open and the other end closed, the air-powder tube (11) passes through the closed end of the transition channel (2) and then extends into the interior of the burner body, and an igniter and / or a flame detector is installed in the transition channel (2); The transition channel (2) is a conical, elliptical or cylindrical blunt body, and the widest diameter of the transition channel (2) should be smaller than the inner diameter of the inner secondary air guide cylinder (3), and the narrowest diameter should be larger than the maximum diameter of the igniter and / or flame detector.

6. A method for using the dual-channel reverse-jet swirl burner according to claim 4 or 5, characterized in that: The following steps are involved: 1) The air enters the burner body in two ways, one of the air passes through the movable axial impeller assembly (7) and the inner secondary air channel to form a rotating inner secondary air with a tangential velocity and directly enters the stable combustion chamber (5), and the inner secondary air channel and the transition channel (2) work together to form a nested high-temperature reflow zone; 2) At the same time, the coal powder airflow enters the high-temperature recirculation zone through the recirculation channel formed by the air-powder pipe (11) and the recirculation cap (12). The coal powder presents a concentration distribution of thick outside and thin inside. The coal powder is preheated to 900-1000°C in the high-temperature recirculation zone. The coal powder is pyrolyzed in the low-oxygen and hot high-temperature recirculation zone and is mixed with the internal secondary air at the closed end of the transition channel (2) to form a main flame. The coal powder airflow swirls and burns in the burner body. 3) Another path of the air passes through the external secondary air channel to form external secondary air. A portion of the external secondary air passes through the expansion of the external secondary air guide tube (4) to form a cooling air layer flowing along the wall of the combustion stabilizing chamber (5) to cool the combustion stabilizing chamber (5) and the rectifying chamber (6), so that the wall temperatures of the combustion stabilizing chamber (5) and the rectifying chamber (6) are lower than 40°C; another portion of the external secondary air and the main flame pass through the rectifying chamber (6) to form a high-speed jet flame of wind-enclosed fire and enter the furnace.

7. The method of use according to claim 6, characterized in that: The swirl number of the rotating airflow generated by the movable axial impeller assembly (7) should be controlled within the range of 0 to 2, the wind speed of the external secondary air should be controlled within the range of 20 to 50 m / s, and the ratio of the internal secondary air to the external secondary air is 1:

2.

8. The method of use according to claim 6, characterized in that: In the above step 3), the cross-sectional area of ​​the outer secondary air channel is adjusted by the movable positioning component (8), thereby adjusting the wind speed of the outer secondary air and controlling the mixing rate of the inner secondary air and the outer secondary air.

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