Burner capable of reducing emission of nitrogen oxides

Abstract

The embodiment of the invention provides a combustor capable of reducing nitrogen oxide emission, and relates to the field of combustors. Comprising an air inlet, an air distribution chamber, a main gas fuel inlet channel, a main gas fuel distribution chamber, a premixing pipe array, an on-duty cyclone and a combustor shell. The air inlet is formed in one side of the combustor shell; the premixing pipe array is mounted in the combustor shell; the main gas fuel distribution chamber is installed at one end of the premixing pipe array, and the other end of the premixing pipe array extends out of the side, away from the air inlet, of the combustor shell. The main gas fuel inlet channel is installed on the combustor shell. The equipment can accurately control the temperature distribution in the whole combustion area, reduce the combustion temperature and reduce the high-temperature area, so that the emission of nitrogen oxides is reduced, and meanwhile, the premixed combustion pressure pulsation amplitude is inhibited; and the structure simultaneously meets the technical requirements of safe, efficient, stable and low-nitrogen combustion.

Description

Technical Field

[0001] The invention relates to the field of burners, in particular to a burner for reducing nitrogen oxide emissions. Background Art

[0002] In response to the increasingly serious climate problems such as acid rain, photochemical smog, and global warming, low nitrogen and low carbon emissions have become the primary goal of environmental protection in countries around the world. Among the various sources of carbon emissions and nitrogen oxide emissions, the burner industry accounts for a large proportion. If it is not controlled, 25% of the world's carbon emissions will come from the burner industry by 2050. At present, traditional fossil fuels have a high carbon content and cannot meet the demand for low carbon emissions. Hydrogen, as a new type of green energy, reacts with oxygen to produce water or water vapor. It has the advantages of wide combustion, high calorific value and zero carbon emissions. It is a fuel with great development potential, especially in the field of industrial and civil burners.

[0003] Traditional burners often use a swirl flame stabilization combustion organization method, where all fuel is supplied at once from the fuel nozzle placed at the head, and the combustion air enters the combustion zone from the head, main combustion hole, and mixing hole for supplementary combustion. This combustion organization method will lead to problems such as high combustion temperature in the combustion zone and large high-temperature area.

[0004] If hydrogen is burned directly in such a burner, high nitrogen oxide emissions will be faced. Therefore, the traditional burner that uses swirl flame stabilization and air combustion along the axial direction of the burner is no longer suitable for hydrogen combustion. Therefore, it is particularly important to propose a burner that can ensure stable combustion while reducing nitrogen oxide emissions.

[0005] Based on this, the present invention is proposed. Summary of the invention

[0006] According to an embodiment of the present invention, a burner for reducing nitrogen oxide emissions is provided to solve the existing background problems.

[0007] In a first aspect of the present invention, a burner for reducing nitrogen oxide emissions is provided.

[0008] The burner for reducing nitrogen oxide emissions comprises: an air inlet, an air distribution chamber, a main gas fuel inlet passage, a main gas fuel distribution chamber, a premixing tube array, a duty class swirler and a burner casing;

[0009] The air inlet is opened on one side of the burner casing; the premixing tube array is installed in the burner casing; the main gas fuel distribution chamber is installed at one end of the premixing tube array, and the other end of the premixing tube array extends out of the burner casing away from the air inlet; the main gas fuel inlet channel is installed on the burner casing; an air distribution chamber is formed between the premixing tube array and the burner casing; the duty class swirler is installed at the center position of the burner casing, one end of the duty class swirler corresponds to the air inlet, and the other end of the duty class swirler extends out of the burner casing.

[0010] Preferably, the premixing tube array consists of a plurality of premixing tubes.

[0011] Preferably, the premixing tube comprises: a premixing tube body, a gas fuel jet hole, an air jet hole, a contraction section and a premixed gas outlet;

[0012] One end of the premixing tube body extends into the inner cavity of the main gas fuel distribution chamber, and the other end of the premixing tube body extends out of the side of the burner shell away from the air inlet; there are a plurality of gas fuel jet holes, which are respectively opened at the end of the premixing tube body extending into the main gas fuel distribution chamber; there are a plurality of air jet holes, which are respectively opened on the premixing tube body, and the air jet holes are located in the air distribution chamber; one end of the premixing tube body extending out of the burner shell forms a premixed gas outlet, and a contraction section is provided on the side of the premixing tube body facing the premixed gas outlet.

[0013] Preferably, the duty class swirler comprises: a duty gas fuel inlet channel, a duty air inlet, a fuel spray hole and a venturi;

[0014] The duty gas fuel inlet channel is installed at the center position of the burner shell; there are a plurality of fuel spray holes, which are respectively opened at one end of the duty gas fuel inlet channel away from the air inlet; the venturi tube is installed at one end of the duty gas fuel inlet channel away from the air inlet, and the venturi tube penetrates the outer wall of the burner shell, and the end of the duty gas fuel inlet channel with the fuel spray hole extends into the venturi tube; the venturi tube is located between the inner wall of one end of the burner shell and the outer wall of the duty gas fuel inlet channel to form a duty air inlet.

[0015] Preferably, the duty class swirler further comprises swirler blades, and the swirler blades are installed between the venturi and the duty gas fuel inlet passage.

[0016] Preferably, the length of the air distribution chamber is 20 mm to 1000 mm; the diameter length of the air distribution chamber is 50 mm to 2500 mm.

[0017] Preferably, the length of the main gas fuel distribution chamber is 20 mm to 500 mm; the diameter of the main gas fuel distribution chamber is 50 mm to 1000 mm.

[0018] Preferably, the diameter of the premixing tube body is 3 mm to 50 mm; the length of the premixing tube body is 10 mm to 1000 mm.

[0019] Preferably, the diameter of the gas fuel jet hole is 0.2 mm to 5 mm, the angle with the axis of the premixing tube body is -60° to 60°, and the number of the gas fuel jet hole is 1 to 20.

[0020] Preferably, the air jet holes have a length of 2 to 100 mm and a width of 0.5 to 25 mm, and the direction of their maximum length is parallel to the axis of the premixing tube body; and the number of each row arranged circumferentially is 1 to 40.

[0021] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0022] 1. The present invention provides a burner for reducing nitrogen oxide emissions. The design of the air distribution chamber can make the combustion air evenly enter the premixing tubes at different positions, so as to achieve a uniform equivalence ratio of the premixed gas in the premixing tubes, thereby enabling the gas fuel and the combustion air to form a combustible gas with a controllable equivalence ratio in a large number of premixing tubes, and forming a large number of premixed combustion small flames at the outlet of the premixing tubes, which can reduce the combustion temperature and the area of ​​the high-temperature zone. Through this micro-premixed combustion, the amount of nitrogen oxides generated can be reduced.

[0023] 2. The design of the median-class swirler of the present invention enables a small amount of gas fuel and combustion-supporting air to diffuse and burn at its outlet, forming a small-area, high-temperature, stable small flame as an ignition source, igniting the combustible premixed gas at the outlet of the premixing tube and reducing the pressure pulsation amplitude of the premixed combustion.

[0024] In summary, the equipment of the present invention can accurately control the temperature distribution in the entire combustion zone, reduce the combustion temperature, reduce the high-temperature area, and thus reduce nitrogen oxide emissions, while suppressing the pulsation amplitude of the premixed combustion pressure; the structure also takes into account the combustion technical requirements of safety, efficiency, stability, and low nitrogen.

[0025] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other features, advantages and aspects of the embodiments of the present invention will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0027] Figure 1 A front cross-sectional view of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0028] Figure 2 A right side view of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0029] Figure 3 A front cross-sectional view of a burner premixing tube body for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0030] Figure 4 An enlarged view of a burner at A for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0031] Figure 5 A front cross-sectional view of a duty class swirler of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0032] Figure 6 An enlarged view of a burner at position B for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0033] Figure 7 An axial cross-sectional view of a premixing tube body of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0034] Figure 8 Another distribution schematic diagram of a burner premixing tube body for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0035] Fig. 9 Another schematic diagram of the bending direction distribution of the transition section of the burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0036] Fig.10 An internal fuel concentration distribution analysis diagram of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0037] Fig.11 An internal pressure distribution analysis diagram of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0038] Fig.12 An external temperature distribution analysis diagram of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0039] Fig.13 An internal temperature distribution analysis diagram of a burner for reducing nitrogen oxide emissions according to an embodiment of the present invention is shown;

[0040] Fig.14 An external NOx distribution analysis diagram of a burner for reducing NOx emissions according to an embodiment of the present invention is shown.

[0041] The reference numerals are as follows:

[0042] 1. Air inlet, 2. Air distribution chamber, 3. Main gas fuel inlet channel, 4. Main gas fuel distribution chamber, 5. Premixing tube array, 6. Duty gas fuel inlet channel, 7. Duty air inlet, 8. Duty class swirler, 9. Burner casing, 10. Premixing tube body, 11. Gas fuel jet hole, 12. Air jet hole, 13. Contraction section, 14. Premixing gas outlet, 15. Fuel spray hole, 16. Swirl blade, 17. Venturi tube. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the 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.

[0044] In addition, the term "and / or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0045] like Figure 1 and Figure 2 As shown, the burner for reducing nitrogen oxide emissions is composed of an air inlet 1, an air distribution chamber 2, a main gas fuel inlet channel 3, a main gas fuel distribution chamber 4, a premixing tube array 5, a duty class swirler 8, and a burner housing 9. Figure 1As shown. The burner casing 9 is a hollow cavity structure, and the air inlet 1 is opened on one side of the burner casing 9, and the air enters along the axial direction of the burner casing 9. The premixing tube array 5 is installed in the burner casing 9, and the fixed casing 9 is mainly used to install and fix the premixing tube array 5 and protect the premixing tube array 5. The main gas fuel distribution chamber 4 is installed at one end of the premixing tube array 5, and the other end of the premixing tube array 5 extends out of the side of the burner casing 9 away from the air inlet 1. The main gas fuel inlet channel 3 is installed on the burner casing 9, one end of the main gas fuel inlet channel 3 is connected to the outside, and the other end extends into the main gas fuel distribution chamber 4. An air distribution chamber 2 is formed between the premixing tube array 5 and the burner casing 9. The air distribution chamber 2 is a cylindrical structure, and its cross-sectional shape can be a constant cross-section or a variable cross-section; its axis can be a straight line or a curve, including a circular arc, an elliptical arc, a parabola, etc. In this embodiment, a circular constant cross-section and a straight axis are taken as an example, and the length L of the air distribution chamber 2 A is 500mm, its diameter D A The cross-sectional shape of the main gas fuel distribution chamber 4 can be circular or other shapes, and its shape is adapted to the cross-sectional shape of the air distribution chamber 2. In this embodiment, it is circular. The duty class swirler 8 is installed at the center of the burner housing 9, one end of the duty class swirler 8 corresponds to the air inlet 1, and the other end of the duty class swirler 8 extends out of the burner housing 9.

[0046] like Figure 3 and Figure 4 As shown, the premixing tube array 5 is composed of a plurality of premixing tubes, and a single premixing tube is composed of a premixing tube body 10, a gas fuel jet hole 11, an air jet hole 12, a contraction section 13 and a premixed gas outlet 14. One end of the premixing tube body 10 extends into the inner cavity of the main gas fuel distribution chamber 4, and the other end of the premixing tube body 10 extends out of the burner casing 9 away from the air inlet 1. The cross-section of the premixing tube body 10 can be a circular tube or other cross-sectional shapes; the premixing tube body 10 can be a straight tube or can be bent at a certain angle as required. This embodiment takes a circular straight tube as an example, and the diameter D of the premixing tube body 10 is P 40mm, the length of the premixing tube body is 10L P500mm. There are a plurality of gas fuel injection holes 11, which are respectively opened at one end of the premixing tube body 10 extending into the main gas fuel distribution chamber 4. The opening shape of the gas fuel injection hole 11 can be circular, rectangular, rhombus, hexagonal, triangular, elliptical, racetrack-shaped, arched, etc.; its channel can be a channel with a uniform cross-section, or a contraction channel or an expansion channel; its axis can be coaxial with the premixing tube body 10, perpendicular, or at a certain angle to the axis of the premixing tube body 10. This embodiment takes a circular channel with a uniform cross-section as an example, and the diameter D of the gas fuel injection hole 11 is FJ is 3 mm, the angle α with the axis of the premixing tube body 10 is 30°, and the number N FJ There are 10 air jet holes 12. The air jet holes 12 are provided on the side wall of the premixing tube body 10, and the air jet holes 12 are located in the air distribution chamber 2. The opening shape of the air jet holes 12 can be circular, rectangular, diamond, hexagonal, triangular, elliptical, racetrack, arched, etc. The present invention takes the racetrack shape as an example, and the length L of the air jet hole 12 is AJ 50mm, width W AJ The diameter of the premixing tube body 10 is 15 mm, and the direction of its maximum length is parallel to the axis of the premixing tube body 10. The axis of the opening is offset from the axis of the premixing tube body 10 at a certain distance. The structure with the offset can introduce tangential momentum into the air jet. In addition, the air jet holes 12 can be divided into multiple rows along the axis of the premixing tube body 10, and the number of holes in each row arranged along the circumferential direction is 6. The end of the premixing tube body 10 extending out of the burner casing 9 forms a premixed gas outlet 14. The premixing tube body 10 is provided with a contraction section 13 on one side facing the premixed gas outlet 14. The contraction section 13 is arranged to reduce in diameter in the direction of the premixed gas outlet 14, and the gas flow rate is increased by reducing the diameter. The contraction section 13 is mainly used to eliminate the low flow velocity area of ​​the premixed gas at the premixed gas outlet 14. The generatrix of the contraction section 13 can be a straight line or a curve, wherein the available curve shapes include the Witosinski curve, the hyperbola, the double twisted line, etc. In this embodiment, it is a curve, and the end of the contraction section 13 close to the premixed gas outlet 14 is bent toward the axial direction of the burner casing 9.

[0047] It is worth noting that the manner in which the plurality of premixing tubes in this embodiment form the premixing tube array 5 is uniformly distributed along the circumference at equal intervals; however, this is not limited to this distribution manner, and may also be a non-uniform distribution manner, such as Figure 8 At the same time, the end of the contraction section 13 on the premixing tube body 10 close to the premixed gas outlet 14 is bent toward the axial direction of the burner housing 9; but it is not limited to this arrangement, and can also be distributed in other arrangements, such as Fig. 9 As shown, the bending direction can also be based on the centripetal bending and then rotated around its own axis by a certain angle.

[0048] The above structure can make the gas fuel and combustion air form combustible gas with controllable equivalent ratio in a large number of premixing tubes, and form a large number of premixed combustion small flames at the outlet of the premixing tube, which can reduce the combustion temperature and the area of ​​the high temperature zone. Through this micro-premixed combustion, the amount of nitrogen oxides generated can be reduced. At the same time, the design of the air distribution chamber can make the combustion air enter the premixing tubes at different positions evenly, so as to achieve a uniform equivalent ratio of the premixed gas in the premixing tube, and the internal fuel concentration distribution is as follows: Fig.10 As shown, the pressure distribution is Fig.11 shown.

[0049] refer to Figure 5 and Figure 6 The duty class swirler 8 is composed of a duty gas fuel inlet channel 6, a duty air inlet 7, a fuel spray hole 15, a swirler blade 16, and a venturi 17. The purpose of the duty class swirler 8 is to form a central duty diffusion flame. The duty gas fuel inlet channel 6 is installed at the center of the burner casing 9. There are a number of fuel spray holes 15, which are respectively opened at one end of the duty gas fuel inlet channel 6 away from the air inlet 1. The venturi 17 is installed at one end of the duty gas fuel inlet channel 6 away from the air inlet 1. The venturi 17 (Venturi tube, a conventional tubular component that uses changes in fluid flow rate to generate pressure difference) passes through the outer wall of the burner casing 9, and the end of the duty gas fuel inlet channel 6 with the fuel spray hole 15 extends into the venturi 17. The inner diameter of the venturi tube 17 is larger than the outer diameter of the duty gas fuel inlet channel 6. The venturi tube 17 is located between the inner wall of one end of the burner housing 9 and the outer wall of the duty gas fuel inlet channel 6 to form a duty air inlet 7. There are a number of swirler blades 16, which are equidistantly installed between the venturi tube 17 and the duty gas fuel inlet channel 6 along the circumferential direction. These swirler blades 16 together form a swirl structure, and there is a tangential airflow channel between two adjacent swirler blades 16, which can introduce tangential velocity into the air in the venturi tube 17 to form a rotating airflow, thereby accelerating the mixing of air and gas fuel, and forming a low-pressure recirculation zone to stabilize the central duty flame. The swirler blades 16 can be oblique hole type, straight plate type, curved plate type, streamlined blade type, etc., and the streamlined blade type is selected in this embodiment. The fuel nozzle 15 is used for the fuel supply of the central duty diffusion flame, and its forms include: direct injection nozzle, centrifugal atomizing nozzle, air-assisted atomizing nozzle, evaporation tube nozzle and a combination of the above nozzles.

[0050] When the above structure is in use, the combustion-supporting air enters the air distribution chamber 2 from the air inlet 1, and enters the premixing tube body 10 through the air jet hole 12. Since the premixing tubes in the premixing tube array 5 are evenly distributed, the combustion-supporting air in the air distribution chamber 2 can evenly enter the premixing tube array 5. The gas fuel enters the main gas fuel distribution chamber 4 from the main gas fuel inlet channel 3, and enters the premixing tube body 10 through the gas fuel jet hole 11. The gas fuel and air are mixed in the premixing tube body 10 to form a premixed gas, and the mixed premixed gas passes through the contraction section 13 and is ejected from the premixed gas outlet 14. The above structure enables this part of the gas fuel to achieve premixed combustion, so as to reduce the combustion temperature and the area of ​​the high-temperature zone, thereby reducing the amount of nitrogen oxides generated.

[0051] This structure enables a small amount of gas fuel and combustion-supporting air to diffuse and burn at the outlet of the central value class cyclone 8, forming a small area, high temperature, stable small flame as an ignition source, igniting the combustible premixed gas at the outlet of the premixing pipe, and reducing the pressure pulsation amplitude of the premixed combustion. The pressure distribution is as follows Fig.11 As shown, the external temperature distribution analysis diagram is as follows Fig.12 As shown, the internal temperature distribution analysis is as follows Fig.13 As shown, the NOx distribution analysis diagram outside the burner is as follows Fig.14 shown.

[0052] In the above structure, the main gas fuel distribution chamber 4 can be divided into a plurality of chambers, each of which is separately provided with a gas fuel inlet channel 3 connected to the outside, so that gas fuel is separately introduced into the main gas fuel distribution chamber 4, and the gas fuel can be determined to enter certain designated premixing tubes in the premixing tube array 5 according to the power output requirement of the burner. For example, when the power requirement of the burner is small, gas fuel is only supplied to one main gas fuel inlet 3, and premixed combustible gas is formed in a small number of premixing tubes. When the power requirement of the burner is large, gas fuel is supplied to multiple main gas fuel inlets 3, and premixed combustible gas is formed in a large number of premixing tubes. The present invention takes a single chamber with a circular cross-section as an example, the chamber length LF of the main gas fuel distribution chamber 4 is 300mm, and the chamber diameter DF of the main gas fuel distribution chamber 4 is 500mm. The main gas fuel distribution chamber 4 of this structure is composed of a plurality of chambers, and the fuel supply can be flexibly adjusted according to the power output requirement of the burner, so that the premixed gas equivalence ratio does not change much at different power outputs, thereby ensuring extremely high combustion efficiency.

[0053] In addition, a small amount of gas fuel enters the duty class swirler 8, specifically: the duty gas fuel inlet channel 6 is connected to the gas fuel pipeline at one end facing the air inlet 1 in advance, the gas fuel enters from one end of the duty gas fuel inlet channel 6, is ejected through multiple fuel nozzles 15, and is mixed with the air passing through the duty air inlet 7 and the swirler blades 16 in the venturi 17 area, and the mixed gas is ignited after being ejected from the venturi 17. The air entering through the duty air inlet 7 can improve the mixing efficiency of air and combustible gas through the action of the swirler blades 16, and fully mix them. At the same time, the venturi 17 uses its special structure, that is, the shape of contraction-throat-expansion, to accelerate the flow rate of the gas flowing through the throat. In the burner, this helps to quickly transport air and fuel to the combustion area and improve the combustion efficiency. And according to Bernoulli's principle, an increase in gas flow rate will lead to a decrease in pressure. The venturi generates negative pressure in the throat, which can attract the surrounding air and fuel and promote their mixing. When in use, the gas output through the venturi 17 is ignited first, and this part of the fuel is diffused and burned to form a small stable flame, providing a stable ignition source for the premixed gas ejected from the premixed gas outlet 14 and reducing the pressure pulsation amplitude of the premixed combustion.

[0054] It is worth noting that the burner for reducing nitrogen oxide emissions proposed in the present invention can significantly reduce the generation of nitrogen oxides when using hydrogen as gas fuel, but the burner is not limited to using hydrogen as fuel, and other gas fuels can also be used, such as natural biogas, natural gas, liquefied gas, and processed coke oven gas, water gas, generator gas, etc.

[0055] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A burner for reducing nitrogen oxide emissions, characterized in that: include: An air inlet (1), an air distribution chamber (2), a main gas fuel inlet passage (3), a main gas fuel distribution chamber (4), a premixing tube array (5), a duty class swirler (8) and a burner casing (9); The air inlet (1) is opened on one side of the burner casing (9); the premixing tube array (5) is installed in the burner casing (9); the main gas fuel distribution chamber (4) is installed at one end of the premixing tube array (5), and the other end of the premixing tube array (5) extends out of the burner casing (9) away from the air inlet (1); the main gas fuel inlet channel (3) is installed on the burner casing (9); an air distribution chamber (2) is formed between the premixing tube array (5) and the burner casing (9); the duty class swirler (8) is installed at the center position of the burner casing (9), one end of the duty class swirler (8) corresponds to the air inlet (1), and the other end of the duty class swirler (8) extends out of the burner casing (9).

2. The burner for reducing nitrogen oxide emissions according to claim 1, characterized in that: The premixing tube array (5) consists of a plurality of premixing tubes.

3. The burner for reducing nitrogen oxide emissions according to claim 2, characterized in that: The premixing tube comprises: a premixing tube body (10), a gas fuel jet hole (11), an air jet hole (12), a contraction section (13) and a premixed gas outlet (14); One end of the premixing tube body (10) extends into the inner cavity of the main gas fuel distribution chamber (4), and the other end of the premixing tube body (10) extends out of the burner casing (9) on a side away from the air inlet (1); there are a plurality of gas fuel jet holes (11), which are respectively arranged at one end of the premixing tube body (10) extending into the main gas fuel distribution chamber (4); there are a plurality of air jet holes (12), which are respectively arranged on the premixing tube body (10), and the air jet holes (12) are located in the air distribution chamber (2); one end of the premixing tube body (10) extending out of the burner casing (9) forms a premixed gas outlet (14), and a contraction section (13) is provided on the side of the premixing tube body (10) facing the premixed gas outlet (14).

4. The burner for reducing nitrogen oxide emissions according to claim 3, characterized in that: The duty swirler (8) comprises: a duty gas fuel inlet channel (6), a duty air inlet (7), a fuel spray hole (15) and a venturi (17); The duty gas fuel inlet channel (6) is installed at the center of the burner housing (9); there are a plurality of fuel spray holes (15), which are respectively opened at one end of the duty gas fuel inlet channel (6) away from the air inlet (1); the venturi tube (17) is installed at one end of the duty gas fuel inlet channel (6) away from the air inlet (1), and the venturi tube (17) penetrates the outer wall of the burner housing (9), and one end of the duty gas fuel inlet channel (6) provided with the fuel spray hole (15) extends into the venturi tube (17); the venturi tube (17) is located between the inner wall of one end of the burner housing (9) and the outer wall of the duty gas fuel inlet channel (6) to form a duty air inlet (7).

5. The burner for reducing nitrogen oxide emissions according to claim 4, characterized in that: The duty class swirler (8) further comprises a swirler blade (16), and the swirler blade (16) is installed between the venturi (17) and the duty gas fuel inlet passage (6).

6. The burner for reducing nitrogen oxide emissions according to claim 5, characterized in that: The length of the air distribution chamber (2) is 20 mm to 1000 mm; the diameter length of the air distribution chamber (2) is 50 mm to 2500 mm.

7. The burner for reducing nitrogen oxide emissions according to claim 6, characterized in that: The main gas fuel distribution chamber (4) has a chamber length of 20 mm to 500 mm; and a chamber diameter of 50 mm to 1000 mm.

8. The burner for reducing nitrogen oxide emissions according to claim 7, characterized in that: The diameter of the premixing tube body (10) is 3 mm to 50 mm; the length of the premixing tube body (10) is 10 to 1000 mm.

9. The burner for reducing nitrogen oxide emissions according to claim 8, characterized in that: The diameter of the gas fuel jet hole (11) is 0.2 mm to 5 mm, the angle with the axis of the premixing tube body (10) is -60° to 60°, and the number of the gas fuel jet hole (11) is 1 to 20.

10. The burner for reducing nitrogen oxide emissions according to claim 8, characterized in that: The air jet holes (12) have a length of 2 to 100 mm and a width of 0.5 to 25 mm, and the direction of their maximum length is parallel to the axis of the premixing tube body (10); the number of each row arranged in the circumferential direction is 1 to 40.

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