A flue gas internal circulation ultra-low nitrogen burner and boiler

Abstract

The present invention discloses a flue gas internal circulation ultra-low nitrogen burner and boiler, the flue gas internal circulation ultra-low nitrogen burner comprises: a mounting plate, a diffusion tube vertically arranged on the mounting plate, an inner tube sleeved inside the diffusion tube and protruding longitudinally out of the diffusion tube, a recirculation sleeve sleeved outside the inner tube, a plurality of fuel nozzles arranged around the outside of the recirculation sleeve, a flame stabilizing disk, a central nozzle vertically penetrating the flame stabilizing disk, and a plurality of ignition nozzles arranged around the inner side of the inner tube; the recirculation sleeve is longitudinally separated from the diffusion tube, and a first annular gas mixing inlet is formed by the tail end of the recirculation sleeve, and the fuel nozzle forms a second gas mixing inlet located in front of the first gas mixing inlet. The flue gas internal circulation ultra-low nitrogen burner disclosed by the present invention significantly improves the flue gas circulation utilization rate, reduces the oxygen content and the center flame temperature in the second gas mixing channel, thereby effectively reducing the amount of nitrogen oxides generated and saving fuel consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of low-nitrogen burners, and in particular to an ultra-low-nitrogen burner with internal circulation of flue gas and a boiler based on the ultra-low-nitrogen burner with internal circulation of flue gas. Background Art

[0002] Industrial boilers, tunnel kilns and large industrial heaters are usually equipped with burners that use natural gas (mainly methane) or fossil fuels such as oil as fuel to generate heat through combustion. The burners in the prior art basically use diffusion combustion technology, and a main spray gun and a cyclone disk are usually installed in the burner. After the natural gas is preheated in the front half of the main spray gun, it is mixed with air and then burned. However, this type of gas burner still has a high NO in the exhaust gas. X Low nitrogen burner is a burner designed to reduce the amount of NOx that is harmful to the environment during combustion. X A new type of burner that can produce nitrogen oxides (i.e. nitrogen oxides).

[0003] After careful search, the applicant found that the Chinese invention patent application with publication number CN102607025A disclosed a gas back-injection low premixed NOx combustion device and a combustion method thereof. A peripheral axial flow air channel is arranged between the outer ring periphery of the cyclone and the inside of the throat, and back-injection hammer gas guns are arranged in the throat radial direction. However, the prior art still has unstable fuel combustion and cannot fundamentally solve the disadvantage of excessively high NOx emissions from traditional gas burners. In addition, the blades of the cyclone in the prior art are easily damaged under high temperature conditions, so there is also a defect of low service life.

[0004] In addition, the Chinese invention patent with publication number CN109099425A also discloses a flue gas internal circulation ultra-low nitrogen burner. This prior art uses a stable combustion fuel pipe and a swirler to stabilize the flame. Thermal nitrogen oxides are N in the combustion air. 2Nitrogen oxides generated by oxidation at high temperatures are also the largest source of nitrogen oxides in boiler combustion and the key focus of low nitrogen oxide emission control. In the prior art, although the swirler is provided to stabilize the flame, it still cannot reduce the temperature of the central flame near the conical ring and the swirler, which can easily lead to high local temperatures and produce excessive thermal nitrogen oxides. Although the prior art also points out that adding a conical ring to the outside of the swirler and part of the fuel sprayed from the graded fuel pipe hits the conical ring can increase the mixing of fuel and air, promote combustion stability, and promote the formation of internal circulation of flue gas, reducing the temperature of the combustion area. However, the applicant pointed out that the swirler in the prior art is recessed inside the center of the conical ring, and the conical ring can actually only play a technical effect of gathering the flame. Although the flue gas entrainment ring disclosed therein can achieve a certain degree of internal circulation of the flue gas, the circle of entrainment holes opened by the flue gas entrainment ring is far away from the cyclone, which leads to doubts about the technical effect of claiming that the provision of a flue gas entrainment ring can significantly reduce nitrogen oxides, and the burner disclosed in the prior art is not ideal for controlling the emission of nitrogen oxides.

[0005] In view of this, it is necessary to improve the ultra-low nitrogen burner in the prior art to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to disclose an ultra-low nitrogen burner with internal flue gas circulation and a boiler to overcome the above-mentioned defects of the burners in the prior art, especially to further improve the flue gas circulation utilization rate, reduce the flame temperature, reduce the amount of nitrogen oxides produced, and save fuel consumption.

[0007] To achieve one of the above purposes, the present invention first discloses a flue gas internal circulation ultra-low nitrogen burner, comprising:

[0008] Mounting plate,

[0009] The diffuser is vertically mounted on the mounting plate.

[0010] The inner cylinder is sleeved inside the diffusion cylinder and protrudes longitudinally out of the diffusion cylinder.

[0011] The recirculation sleeve is mounted on the outside of the inner cylinder.

[0012] A plurality of fuel nozzles are arranged around the outside of the recirculation sleeve,

[0013] Flame stabilizing plate,

[0014] a central nozzle vertically extending through the flame stabilizing disk, and

[0015] A plurality of ignition nozzles arranged in a ring-shaped manner on the inner side of the inner tube;

[0016] The recirculation sleeve is longitudinally separated from the diffuser, and a first annular air mixing inlet is formed by the tail end of the recirculation sleeve, and the fuel nozzle forms a second air mixing inlet located in front of the first air mixing inlet.

[0017] As a further improvement of the present invention, the fuel nozzle is composed of a main fuel nozzle and an air pipe which are longitudinally and separately arranged, the second mixing air inlet is formed by longitudinally separating the main fuel nozzle and the air pipe, and the inner diameter of the main fuel nozzle is larger than the inner diameter of the air pipe.

[0018] As a further improvement of the present invention, a first gas mixing channel with a cross-sectional area of ​​S1 is formed inside the main fuel nozzle, and a first gas channel with a cross-sectional area of ​​S2 is formed inside the gas delivery pipe;

[0019] The ratio of the cross-sectional area S1 of the first gas mixing channel to the cross-sectional area S2 of the first gas channel is 3:1 to 2:1.

[0020] As a further improvement of the present invention, a second gas channel with a cross-sectional area of ​​S3 is formed inside the central nozzle, and a third gas channel with a cross-sectional area of ​​S4 is formed inside the pilot nozzle; the mounting plate connects the burner body and the gas delivery main pipe.

[0021] As a further improvement of the present invention, the free end of the main fuel nozzle forms an inclined surface facing outward, and the angle formed by the inclined surface and the central axis of the central nozzle is an acute angle.

[0022] As a further improvement of the present invention, the free end of the fuel nozzle is set back and arranged at the rear side of the injection port of the recirculation sleeve.

[0023] As a further improvement of the present invention, the flame stabilizing plate is provided with flame stabilizing holes, so as to form a dense longitudinal flame through the flame stabilizing holes;

[0024] The central nozzle extends through the end of the flame stabilizing disk and is provided with a plurality of lateral injection holes distributed in an annular manner, so as to form a lateral flame through the lateral injection holes;

[0025] The flame stabilizing disk is laterally recessed and arranged inside the inner tube, and laterally abuts against the pilot nozzle, so that the flame stabilizing disk and the inner tube jointly clamp the pilot nozzle, and the pilot nozzle longitudinally extends through the flame stabilizing disk.

[0026] As a further improvement of the present invention, one end of the diffuser tube close to the recirculation sleeve forms a diameter-shrinking ring portion that shrinks radially inward.

[0027] As a further improvement of the present invention, a heat preservation tube partially wrapping the gas pipe and the diffuser tube is arranged outside the diffuser tube, and the interior of the heat preservation tube is filled with heat preservation material.

[0028] As a further improvement of the present invention, a plurality of radially arranged connecting plates are provided between the recycling sleeve and the inner cylinder, and the connecting plates extend along the longitudinal extension direction of the recycling sleeve to the outer wall surface of the diameter reduction ring portion.

[0029] Similarly, the present invention also discloses a boiler, which is equipped with at least one ultra-low nitrogen burner with internal circulation of flue gas as described in any of the above inventions.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In the present invention, the second air mixing inlet formed by the fuel nozzle is provided to improve the recycling of the flue gas formed in the combustion chamber of the boiler during the fuel combustion process; at the same time, by forming a ring-shaped first air mixing inlet at the tail end of the recirculation sleeve and using a diffusion tube, not only the air flow rate is improved but also the recycling rate of the flue gas is further improved; at the same time, since the flue gas with reducing ion components is mixed in the first air mixing channel, the energy density of the fuel delivered to the combustion chamber by the main fuel nozzle is reduced; at the same time, by providing a circle of ignition nozzles, the ignition nozzle can be ignited by the flame stabilizing disk and the outer fuel nozzles can be ignited by the ignition nozzle, which has the advantage of reasonable structural design, and when the fuel nozzle needs to work, the outer fuel nozzles can be ignited by the ignition nozzle, so it has the advantage of easy use, and the central flame temperature is reduced by providing the flame stabilizing disk, thereby reducing the emission of thermal nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the internal structure of an ultra-low nitrogen burner with internal flue gas circulation according to the present invention;

[0033] Figure 2 For Figure 1 A schematic diagram of the external structure of an induced draft device connected to an ultra-low nitrogen burner with internal flue gas circulation is shown;

[0034] Figure 3 A three-dimensional diagram of an ultra-low nitrogen burner with internal flue gas circulation according to the present invention;

[0035] Figure 4 A half-section stereoscopic view of a flue gas internal circulation ultra-low nitrogen burner according to the present invention;

[0036] Figure 5 A side view of an ultra-low nitrogen burner with internal flue gas circulation according to the present invention;

[0037] Figure 6 for Figure 1 The structure diagram of the invention shown is a smoke internal circulation ultra-low nitrogen burner assembled with a furnace wall;

[0038] Figure 7A conceptual diagram of a gas flow path and a flame injection path in a flue gas internal circulation ultra-low nitrogen burner of the present invention;

[0039] Figure 8 For Figure 1 A schematic diagram of the internal structure of an induced draft device connected to an ultra-low nitrogen burner with internal flue gas circulation is shown. DETAILED DESCRIPTION

[0040] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0041] It should be understood that, in the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present technical solution and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present technical solution.

[0042] Embodiment 1:

[0043] Ginseng Figures 1 to 8 A specific implementation of the present invention is disclosed as a flue gas internal circulation ultra-low nitrogen burner.

[0044] Before describing in detail the present invention's flue gas internal circulation ultra-low nitrogen burner, it is necessary to explain the technical concepts involved. Figure 1 and Figure 2 The components shown in the view are horizontally butted and embedded in the Figure 6 The furnace wall 100 can be used as a part of the boiler. The terms "inside" and "outside" indicating spatial orientation are relative to Figure 4 The front-to-rear positional relationship in the terms "lateral front" and "lateral rear" indicating spatial orientation refers to the central axis 200 of the central nozzle 30. Figure 1The longitudinal direction in the perspective shown, wherein the direction away from the mounting plate 52 is the "front", and the direction close to the mounting plate 52 is the "rear". Therefore, "side front" and "side rear" refer to both the radial direction and the longitudinal direction relative to the central axis 200. At the same time, in this embodiment, the term "low nitrogen" and the term "low nitrogen oxides" (low NOx) have equivalent technical meanings. "Fuel" specifically refers to a gas that is fluid and can burn. In this embodiment, the applicant selects natural gas (whose main component is methane, CH 4 ) are used as an exemplary illustration, so “fuel” and “natural gas” in this embodiment can be understood as equivalent technical features.

[0045] Specifically, the present embodiment discloses a flue gas internal circulation ultra-low nitrogen burner, which includes: a mounting plate 52, a diffusion tube 60 vertically arranged on the mounting plate 52, an inner tube 40 sleeved inside the diffusion tube 60 and protruding longitudinally from the diffusion tube 60, a recirculation sleeve 10 sleeved outside the inner tube 40, a plurality of fuel nozzles arranged around the outside of the recirculation sleeve 10, a flame stabilizing plate 31, a central nozzle 30 vertically penetrating the flame stabilizing plate 31, and a plurality of pilot nozzles 80 arranged around the inner side of the inner tube 40. Specifically, the mounting plate 52 is circular and is fitted with the inner wall surface of the furnace wall 100 by bolts (not shown) for reliable connection, so that the entire flue gas internal circulation ultra-low nitrogen burner is installed on the inner wall surface of the furnace wall 100. At the same time, the physical components such as the diffusion tube 60, the central nozzle 30, the recirculation sleeve 10 and the flame stabilizing plate 31 are all made of heat-resistant stainless steel alloys that can withstand more than 1200°C. The free end of the recirculation sleeve 10 (i.e., the end away from the mounting plate 52) forms an outwardly expanding annular flared portion 11, so that the flame radius of the main flame 213 can be expanded through the flared portion 11, so that the natural gas and the air can form a vortex, thereby improving the combustion efficiency of the natural gas. The inner wall surface 111 of the flared portion 11 forms an angle of 45 degrees with the central axis 200 of the central nozzle 30, and the flared portion 11 guides the pilot flame 96 to form an outwardly expanding pilot flame 96.

[0046] The flue gas internal circulation ultra-low nitrogen burner Figure 2 The induced draft device 70 shown is connected. The function of the induced draft device 70 is to inhale air containing oxygen (oxygen content is about 21%) from the outside. The induced draft device 70 includes a burner body 50, a motor 72, a controller 71, and a hood 73 connected to the motor 72. A valve (not shown) for controlling the air flow rate is set in the hood 73, and a valve (not shown) for controlling the gas flow rate is set in the gas delivery main 51. The controller 71 can use a single-chip microcomputer or a PLC-controlled control hardware to control the speed and running time of the motor 72. The controller 71 and the motor 72 are both connected to the mains. Specifically, in this embodiment, the model of the controller 71 is a Siemens LMV intelligent controller.

[0047] The output shaft (not shown) of the motor 72 is provided with blades at the part of the wind hood 73, so that the air flow 300 is formed by the rotation of the blades. The air flow 300 can penetrate the burner body 50, and form the air flow shown by the arrow 94 and the air flow shown by the arrow 99 respectively under the action of the diffuser 60 and the inner cylinder 40. The bottom of the wind hood 73 is provided with an air inlet 74, and the air in the outside enters the wind hood 73 along the arrow 704. The air flow 300 is simultaneously passed into the annular cavity 17 formed by the diffuser 60 and the inner cylinder 40, and the annular cavity 18 formed by the central nozzle 30 and the inner cylinder 40. Air plays a role in combustion during the combustion of natural gas.

[0048] Combined with 2, Figure 6 and Figure 8 As shown, the mounting plate 52 connects the burner body 50 and the gas delivery main pipe 51. Natural gas is introduced into the gas delivery main pipe 51 in the direction of arrow 501. The cross-sectional area of ​​the gas delivery main pipe 51 is S5. The interior of the burner body 50 is a hollow structure and is connected to the gas delivery main pipe 51. The burner body 50 is built with a pipeline 54 and a pipeline 53. The pipeline 54 is connected to the central nozzle 30 to deliver natural gas to the central nozzle 30. The pipelines 53 are arranged in a ring shape and are equal to the number of the pilot nozzles 80, so that each pipeline 53 is connected to the pilot nozzle 80 to independently deliver natural gas to the pilot nozzle 80 (see FIG. 5 ). Figure 8 and Figure 7 The natural gas is introduced into the central nozzle 30 in the direction indicated by the arrow 92.

[0049] Combination Figure 6 As shown, the fuel nozzle is composed of a main fuel nozzle 20 and a gas pipe 21 which are longitudinally and separately arranged, and a plurality of pipelines 215 for independently conveying natural gas to the fuel nozzle can be additionally arranged inside the burner body 50, and the above pipelines 215 are all connected to the gas conveying main pipe 51. Of course, the pipeline 215 for conveying natural gas can also be independently arranged for the fuel nozzle 80, and the pipeline 215 is arranged outside the burner body 50. At the same time, in this embodiment, six pilot nozzles 80 are arranged in a ring; preferably, the pilot nozzle 80 and each main fuel nozzle 20 can be arranged in a manner of pointing to the central axis 200 of the central nozzle 30 together, so as to facilitate the ignition of the main fuel nozzle 20 by the pilot nozzle 80. In particular, by arranging a circle of pilot nozzles 80, it is beneficial to make the combustion of the main flame 213 have better stability, prevent the "de-fire" and "explosion" phenomena that may occur in the ignition process of the flue gas internal circulation ultra-low nitrogen burner, and improve the use safety and combustion stability of the flue gas internal circulation ultra-low nitrogen burner.

[0050] The fuel nozzle is composed of a main fuel nozzle 20 and an air pipe 21 which are longitudinally and separately arranged. The second gas mixture inlet 211 is formed by longitudinally separating the main fuel nozzle 20 and the air pipe 21. The inner diameter of the main fuel nozzle 20 is larger than the inner diameter of the air pipe 21. The main fuel nozzle 20 and the air pipe 21 are coaxial and longitudinally arranged, and are connected to each other by welding through two triangular connectors 218.

[0051] Ginseng Figure 1 As shown, in this embodiment, the main fuel nozzle 20 forms a first gas mixing channel 203 with a cross-sectional area of ​​S1, and the gas delivery pipe 21 forms a first gas channel 217 with a cross-sectional area of ​​S2. The ratio of the cross-sectional area S1 of the first gas mixing channel 203 to the cross-sectional area S2 of the first gas channel 217 is 3:1 to 2:1, and most preferably 2.5:1. The center nozzle 30 forms a second gas channel 307 with a cross-sectional area of ​​S3, and the pilot nozzle 80 forms a third gas channel 803 with a cross-sectional area of ​​S4.

[0052] like Figure 1 As shown, a heat preservation tube 22 partially wrapping the gas delivery pipe 21 and the diffuser 60 can be arranged outside the diffuser 60, and the heat preservation tube 22 is filled with heat preservation material 221. Specifically, the heat preservation material 221 is made of a mixture of asbestos rope and refractory mud.

[0053] In this embodiment, six fuel nozzles are arranged in an annular manner with equal spacing outside the recirculation sleeve 10. The number of the fuel nozzles is not specifically limited, and the number of the fuel nozzles can be increased or decreased according to actual needs, and the six fuel nozzles consume most of the fuel to form the main flame 213 (see Figure 7 The recirculation sleeve 10 is longitudinally separated from the diffuser 60, and the tail end of the recirculation sleeve 10 forms a first annular gas mixture inlet 62, and the fuel nozzle forms a second gas mixture inlet 211 located in front of the first gas mixture inlet 62. As shown by arrow 91, the mixed gas including natural gas and the flue gas refluxed from the second gas mixture inlet 211 flows horizontally in the first gas mixture channel 203.

[0054] The annular cavity 17 delivers fresh air to the second air mixing channel 19 under the action of the air induction device 70, and inhales the refluxed smoke through the first air mixing inlet 62. Specifically, the annular cavity 17 delivers 1M of fresh air to the second air mixing channel 19. 3 The fresh air can be sucked into the return flue gas through the first mixed air inlet 62, about 0.5 to 1 M 3 At the same time, in this embodiment, the first gas channel 217 delivers 1M 3During the process of natural gas mixing, about 0.5 to 1 M of refluxed flue gas can be sucked in through the second gas mixing inlet 211. 3 The fresh air blown into the combustion chamber 400 of the furnace by the draft device 70 is transported to the combustion chamber 400 through the annular cavity 18 .

[0055] The flue gas in the combustion chamber 400 (the oxygen content in the flue gas is 3-5%) is Figure 1 or Figure 7 The flow path shown by the arrow 201 in FIG. 2 enters the first gas mixing channel 203 from the second gas mixing inlet 211. In this embodiment, since a large amount of flue gas with reducing ion components is mixed into the natural gas, the reducing ions include carbon ions, hydrogen ions, and carbon monoxide. By mixing the flue gas with the reducing ion components into the first gas mixing channel 203, the probability of combining nitrogen molecules with oxygen molecules in the combustion chamber 400 during the combustion of the main flame 213 is reduced, and the probability of combining nitrogen molecules with oxygen molecules is fundamentally curbed, thereby significantly reducing the content of thermal nitrogen oxides in the combustion chamber 400; in addition, since the flue gas with the reducing ion components is mixed into the first gas mixing channel 203, the energy density of the natural gas transported from the first fuel gas channel 217 is reduced.

[0056] At the same time, in this embodiment, the recirculation sleeve 10 is coaxial with the inner cylinder 40 and nested to form an annular second gas mixing channel 19. The flue gas is blocked by the furnace wall 100 and forms a flow path shown by the arrow 209, so that the flue gas is recirculated along the flue gas flow path shown by the arrow 301 and the arrow 209, and the flue gas is recirculated from the first gas mixing inlet 62 to the annular second gas mixing channel 19 for re-gasification treatment to reduce the oxygen content in the annular second gas mixing channel 19. The first gas mixing inlet 62 is in a circular ring shape. Arrow 95 is the flow path of the flue gas including air and reflux. Through the above technical solution, not only the recycling rate of the flue gas is improved, but also the oxygen content in the mixed gas formed in the second gas mixing channel 19 by the fresh air transported from the annular cavity 17 to the second gas mixing channel 19 is reduced. Specifically, the oxygen content in the fresh air delivered from the annular cavity 17 to the second gas mixing channel 19 can be reduced from 21% to 10-18%, and while ensuring the stable combustion of the main flame 213 in the combustion chamber 400, an "oxygen-poor zone" is formed in the annular area of ​​the second gas mixing channel 19 away from the mounting plate 52. Since the inner cylinder 40 delivers fresh air to the combustion chamber 400, an "oxygen-rich zone" is formed at the opening of the inner cylinder 40. As a result, the smoke and flame at the end space of the main flame 213 flow back to the "oxygen-rich zone" along the path shown by arrows 97 and 98, thereby ensuring the full combustion of natural gas, while reducing the flame temperature of the main flame 213, and making the flame temperature of the main flame 213 uniform in the combustion chamber 400.

[0057] After actual measurement, the flue gas internal circulation ultra-low nitrogen burner disclosed in this embodiment is used in the furnace forming the combustion chamber 400. When the heat load in the combustion chamber 400 is less than 1200kw / m 3 When the nitrogen oxide emission is less than 28mg / m 3 .

[0058] Ginseng Figure 1 , Figure 3 and Figure 4 As shown, in this embodiment, the flame stabilizing plate 31 is provided with flame stabilizing holes 312, which are uniformly provided in the radial direction in the flame stabilizing plate 31 and communicated with the annular cavity 18. A dense longitudinal flame 314 is formed through the flame stabilizing holes 312. The central nozzle 30 extends through the end of the flame stabilizing plate 31 and is annularly distributed with a plurality of transverse injection holes 311, so as to form a transverse flame 315 through the transverse injection holes 311. The flame stabilizing plate 31 is laterally recessed and arranged inside the inner tube 40, and laterally abuts against the pilot nozzle 80, so as to clamp the pilot nozzle 80 together with the flame stabilizing plate 31 and the inner tube 40, and the pilot nozzle 80 extends longitudinally through the flame stabilizing plate 31, but does not extend longitudinally through the inner tube 40. The function of the pilot nozzle 80 in this embodiment is to form an outward-expanding pilot flame 96, and to ignite the six fuel nozzles on the outside of the recirculation sleeve 10 through the pilot flame 96, so as to form a circle of main flame 213. The pilot nozzle 80 is disposed in close contact with the inner wall surface 401 of the inner tube 40. It should be noted that, as a reasonable variation of this embodiment, the pilot nozzle 80 can also be disposed in close contact with the outer wall surface 402 of the inner tube 40.

[0059] It should be noted that, in this embodiment, a gap 303 with a radial width equal to the outer diameter of the pilot nozzle 80 is still formed between the flame stabilizing disk 31 and the inner cylinder 40, and the air blown in by the induced draft device 70 can be blown along the inner cylinder 40. Figure 4The fuel is sprayed horizontally into the combustion chamber 400 in the direction of the middle arrow 94 to assist the combustion of the pilot nozzle 80 and ensure the continuous and stable combustion of the pilot flame 96. The flame stabilizing plate 31 is arranged in a transverse depression inside the inner tube 40, which is not only conducive to the formation of a stable and short longitudinal flame 314 by the flame stabilizing plate 31, but also can form a stable longitudinal flame 314 in the "oxygen-rich zone" at the opening of the inner tube 40, and the longitudinal flame 314 ignites the pilot nozzle 80, so that the pilot nozzle 80 forms an outward-expanding pilot flame 96, which is conducive to improving the combustion stability of the pilot flame 96, and finally ignites the main flame 213 through the pilot flame 96, thereby significantly improving the stability of the main flame 213, and can reduce the temperature of the longitudinal flame 314, thereby significantly reducing the amount of nitrogen oxides generated in the "oxygen-rich zone" near the flame stabilizing plate 31. An outer circle of fuel nozzles forms a main flame 213 of stable combustion through the pilot flame 96, forming an "oxygen-depleted zone" in the combustion chamber 400. The main flame 213 forms a large-scale flame circulation and heat circulation in the combustion chamber 400 to maintain the stable combustion of a circle of main flame 213, a circle of pilot flame 96 and a central flame (i.e., the longitudinal flame 314).

[0060] At the same time, the end of the central nozzle 30 can be configured as a central combustion head 32 connected by plugging, and the central combustion head 32 is surrounded by a circle of transverse injection holes 311 (see Figure 1 or the central combustion head 32 is omitted, and a circle of transverse injection holes 311 are directly opened at the end of the closed end of the central nozzle 30 (see Figure 4 shown).

[0061] Ginseng Figure 7 As shown, the flue gas internal circulation ultra-low nitrogen burner also includes an ignition electrode 81 arranged close to the central nozzle 30 and parallel thereto, the ignition electrode 81 extends over the flame stabilizing disk 31 and forms an ignition needle 811 that bends radially inward, thereby igniting the natural gas flowing horizontally along the arrow 92 and in the central nozzle 30 through the ignition needle 811 to ignite the entire flame stabilizing disk 31.

[0062] Re-participate Figure 1 As shown, the free end of the main fuel nozzle 20 forms an inclined surface 202 facing outward, and the angle formed by the inclined surface 202 and the central axis 200 of the central nozzle 30 is an acute angle, and specifically between 30 and 60 degrees. In this embodiment, the angle formed by the inclined surface 202 and the central axis 200 of the central nozzle 30 is an acute angle, which means that the angle between the extended surface formed by the inclined surface 202 away from the mounting plate 52 and the central axis 200 is an acute angle. Through the above structure, it is possible to strengthen the Figure 7The diffusion degree of the main flame 213 in the radial direction is shown, and it is helpful to strengthen the recirculation of the reducing flue gas in the combustion chamber 400 toward the mounting plate 52. The reducing flue gas contains carbon ions, hydrogen ions, and carbon monoxide formed by incomplete combustion of natural gas, thereby reducing the content of thermal nitrogen oxides in the combustion chamber 400.

[0063] The free end of the fuel nozzle 20 is set back and arranged at the side and rear of the injection port of the recirculation sleeve 10, that is, the distance d1 is formed between the free end of the fuel nozzle 20 and the expansion part 11. In this embodiment, a circle of inclined surfaces 202 is formed, and each circle of inclined surfaces 202 forms an acute angle with the central axis 200. Through the above structure, the combustion radius of the flame composed of six main flames 213 is further expanded, so that the natural gas and air can form a vortex, thereby accelerating the flue gas from the first gas mixing inlet 62 and the second gas mixing inlet 211 to enter the second gas mixing channel 19 and the first gas mixing channel 203 respectively, so as to further improve the reuse rate and circulation volume of the flue gas. The first gas mixing inlet 62 and the second gas mixing inlet 211 are both annular. At the same time, by forming the free end of the main fuel nozzle 20 with an inclined surface 202 facing outward, the residence time of the natural gas in the high temperature zone is further reduced, thereby curbing the generation of nitrogen oxides. The free end of the main fuel nozzle 20 is an end away from the mounting plate 52.

[0064] Meanwhile, in the present embodiment, the first gas mixture inlet 62 is retracted and arranged at the inner rear of the second gas mixture inlet 211. Since the first gas mixture inlet 62 and the second gas mixture inlet 211 will form a local negative pressure in the combustion chamber 400, through the above technical solution, the flue gas corresponding to the flue gas flow path shown by the arrow 301 and the flue gas corresponding to the flue gas flow path shown by the arrow 201 will not interfere with each other, and the natural gas shown by the arrow 91 will not escape from the second gas mixture inlet 211 and flow into the first gas mixture inlet 62.

[0065] Specifically, the first gas mixing inlet 62 is divided into four fan-shaped flue gas inlets by four connecting plates 12, and the second gas mixing channel 19 with fan-shaped through holes at both ends is formed by the inner cylinder 40, the recirculation sleeve 10 and the connecting plates 12. The mixed gas corresponding to the arrow 95 (the mixed gas includes the fresh air blown in by the induced draft device 70 and the flue gas refluxed from the first gas mixing inlet 62) is blown into the combustion chamber 400 and participates in the combustion.

[0066] Meanwhile, in this embodiment, the sum of the cross-sectional areas S2 of all the first gas channels 217 accounts for 70-90% of the total gas delivery volume of the gas delivery main pipe 51, the cross-sectional areas S3 of all the second gas channels 307 account for 5-15% of the total gas delivery volume of the gas delivery main pipe 51, and the sum of the cross-sectional areas S4 of all the third gas channels 803 accounts for 5-15% of the total gas delivery volume of the gas delivery main pipe 51. Further preferably, the setting of the above-mentioned gas consumption ratio can be further limited to the following:

[0067] The sum of the cross-sectional areas S2 of all the first gas channels 217 accounts for 90% of the total gas delivery volume of the gas delivery main pipe 51, the cross-sectional areas S3 of all the second gas channels 307 account for 5% of the total gas delivery volume of the gas delivery main pipe 51, and the sum of the cross-sectional areas S4 of all the third gas channels 803 accounts for 5% of the total gas delivery volume of the gas delivery main pipe 51. By setting the above-mentioned gas consumption ratio, the continuous and stable combustion of a circle of main flames 213 can be ensured, the flame temperature of the central flame can be reduced to reduce the amount of thermal nitrogen oxides generated, and the stability of the combustion of the main flame 213, the transverse flame 315 and the longitudinal flame 314 can be ensured, which solves the problem that the traditional low-nitrogen burner is prone to "de-ignition" during combustion and the "explosion" phenomenon caused by insufficient combustion of natural gas.

[0068] like Figure 1 , Figure 4 and Figure 7 As shown, in this embodiment, the thickness of the diffuser 60 remains the same as a whole, and a diameter shrinking ring portion 61 that shrinks radially inward is formed at one end of the diffuser 60 close to the recirculation sleeve 10, so as to increase the flow rate of the air flowing through the annular cavity 17 formed between the inner cylinder 40 and the diffuser 60 through the diameter shrinking ring portion 61 and the inner cylinder 40. Specifically, the outer wall of the diameter shrinking ring portion 61 can not only guide the flue gas corresponding to the flue gas flow path shown by the arrow 301, but also collect and compress the air flow shown by the arrow 99 through the inner wall surface 611 of the diameter shrinking ring portion 61, so as to increase the flow rate of the air flow shown by the arrow 99, prevent the air from escaping from the opening of the annular second gas mixing channel 19 to the combustion chamber 400, so as to facilitate the formation of the mixed gas corresponding to the arrow 95.

[0069] In this embodiment, in order to connect the recirculation sleeve 10 and the inner cylinder 40, a plurality of radially arranged connecting plates 12 are arranged between the recirculation sleeve 10 and the inner cylinder 40, and the connecting plates 12 extend along the longitudinal extension direction of the recirculation sleeve 10 to the outer wall surface of the diameter reduction ring portion 61. Thus, by arranging four mutually perpendicular connecting plates 12, the annular second gas mixing channel 19 is divided into four independent sub-channels 304 with fan-shaped cross sections. The cutting direction of the cross section is perpendicular to the central axis 200.

[0070] At the same time, by providing four connecting plates 12, the mixed gas composed of the flue gas returning from the first mixing inlet 62 and the air delivered by the induced draft device 70 flowing through the second mixing channel 19 can be turbulently divided, thereby ensuring that the mixed gas flows more smoothly in the second mixing channel 19 and preventing turbulence of the mixed gas in the second mixing channel 19.

[0071] The ultra-low nitrogen burner with internal flue gas circulation disclosed in this embodiment combines the technical advantages of FIR (Fuel Inner Return) and FGR (Fuel Gas Return) to significantly increase the amount of flue gas circulation in the combustion chamber 400; at the same time, the stable combustion of the main flame 213, the pilot flame 96 and the center flame (i.e., the longitudinal flame 314) is achieved. The ultra-low nitrogen burner with internal flue gas circulation can reduce the flame temperature in the combustion zone, especially the center flame temperature in the "oxygen-rich zone", avoid the formation of local high-temperature zones, reduce the excess air coefficient in the entire combustion chamber 400, and save fuel consumption by about 3% to 5%.

[0072] Embodiment 2:

[0073] Based on the ultra-low nitrogen burner with internal flue gas circulation disclosed in the above-mentioned embodiment 1, this embodiment further discloses a boiler, which is equipped with at least one ultra-low nitrogen burner with internal flue gas circulation disclosed in the embodiment 1.

[0074] It should be noted that the boiler referred to in this embodiment generally refers to a device that can generate heat by burning natural gas or other combustible gas as fuel based on the flue gas internal circulation ultra-low nitrogen burner disclosed in Example 1. The device can be an industrial steam boiler, a tunnel kiln, or a large industrial heater.

[0075] For the specific technical solution of the ultra-low nitrogen burner with internal flue gas circulation disclosed in this embodiment, please refer to the description in Embodiment 1, which will not be repeated here.

[0076] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0077] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0078] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A flue gas internal circulation ultra-low nitrogen burner, characterized in that: include: Mounting plate (52), A diffuser tube (60) vertically disposed on the mounting plate (52), The inner cylinder (40) is sleeved inside the diffusion cylinder (60) and protrudes longitudinally out of the diffusion cylinder (60). A recirculation sleeve (10) is sleeved on the outside of the inner cylinder (40), A plurality of fuel nozzles are arranged around the outside of the recirculation sleeve (10), wherein the fuel nozzles are composed of a main fuel nozzle (20) and an air delivery pipe (21) which are longitudinally and separately arranged. Flame stabilizing plate (31), a central nozzle (30) vertically penetrating the flame stabilizing disk (31), and A plurality of ignition nozzles (80) arranged in a ring-shaped manner on the inner side of the inner tube (40); The recirculation sleeve (10) and the diffuser (60) are separated longitudinally, and a first annular air-mixing inlet (62) is formed by the tail end of the recirculation sleeve (10), and the fuel nozzle forms a second air-mixing inlet (211) located in front of the first air-mixing inlet (62); The free end of the main fuel nozzle (20) forms an inclined surface (202) facing outward, and the angle formed by the inclined surface (202) and the central axis (200) of the central nozzle (30) is an acute angle.

2. The flue gas internal circulation ultra-low nitrogen burner according to claim 1 is characterized in that: The second gas mixture inlet (211) is formed by longitudinally separating the main fuel nozzle (20) and the gas delivery pipe (21), and the inner diameter of the main fuel nozzle (20) is larger than the inner diameter of the gas delivery pipe (21).

3. The flue gas internal circulation ultra-low nitrogen burner according to claim 2 is characterized in that: A first gas mixing channel (203) with a cross-sectional area of ​​S1 is formed inside the main fuel nozzle (20), and a first gas channel (217) with a cross-sectional area of ​​S2 is formed inside the gas delivery pipe (21); The ratio of the cross-sectional area S1 of the first gas mixing channel (203) to the cross-sectional area S2 of the first gas channel (217) is 3:1 to 2:

1.

4. The flue gas internal circulation ultra-low nitrogen burner according to claim 3 is characterized in that: A second gas passage (307) with a cross-sectional area of ​​S3 is formed inside the central nozzle (30), and a third gas passage (803) with a cross-sectional area of ​​S4 is formed inside the pilot nozzle (80); the mounting plate (52) is connected to the burner body (50) and the gas delivery main pipe (51).

5. The flue gas internal circulation ultra-low nitrogen burner according to claim 1 is characterized in that: The free end of the fuel nozzle (20) is retracted and arranged at the rear side of the injection port of the recirculation sleeve (10).

6. The flue gas internal circulation ultra-low nitrogen burner according to claim 1 is characterized in that: The flame stabilizing plate (31) is provided with a flame stabilizing hole (312) so as to form a dense longitudinal flame (314) through the flame stabilizing hole (312); The central nozzle (30) extends through the end portion of the flame stabilizing disk (31) to form a plurality of transverse injection holes (311) distributed in an annular manner, so as to form a transverse flame (315) through the transverse injection holes (311); The flame stabilizing disk (31) is laterally recessed and arranged inside the inner tube (40), and laterally abuts against the ignition nozzle (80) so that the ignition nozzle (80) is clamped together by the flame stabilizing disk (31) and the inner tube (40), and the ignition nozzle (80) extends longitudinally through the flame stabilizing disk (31).

7. The flue gas internal circulation ultra-low nitrogen burner according to claim 1 is characterized in that: The diffuser tube (60) has an end close to the recirculation sleeve (10) formed with a diameter-shrinking ring portion (61) that shrinks radially inward.

8. The flue gas internal circulation ultra-low nitrogen burner according to claim 1 is characterized in that: A heat preservation tube (22) is arranged outside the diffusion tube (60) to partially wrap the gas transmission pipe (21) and the diffusion tube (60), and a heat preservation material (221) is filled inside the heat preservation tube (22).

9. The flue gas internal circulation ultra-low nitrogen burner according to claim 8, characterized in that: A plurality of radially arranged connecting plates (12) are arranged between the recycling sleeve (10) and the inner cylinder (40), and the connecting plates (12) extend along the longitudinal extension direction of the recycling sleeve (10) to the outer wall surface of the diameter reduction ring portion (61).

10. A boiler, characterized in that: The boiler is equipped with at least one flue gas internal circulation ultra-low nitrogen burner according to any one of claims 1 to 9.

Images