Flue gas recirculation and staged combustion coupled low-nitrogen gas burner

Abstract

The invention provides a flue gas recirculation and staged combustion coupled low-nitrogen gas burner, and belongs to the field of gas burners. The problem that an existing combustor cannot control emission of nitric oxide and has stable combustion performance is solved. Wherein the outlet end of the air channel penetrates through the air sleeve, and the inlet end of the on-duty sleeve penetrates through the air sleeve; the first rotational flow blade is arranged on the air sleeve; the second swirl vane is arranged on the on-duty sleeve; the on-duty flame gas pipe sequentially penetrates through the air channel, the air sleeve and the on-duty sleeve, and the outlet end of the on-duty flame gas pipe is provided with a jet hole group; the outlet end of the outer ring main flame gas pipe penetrates through the outer ring mixing pipe; the multiple outer ring fuel gas and flue gas mixing ejectors are arranged at intervals in the circumferential direction of the air sleeve; the outlet end of the inner-ring main flame gas pipe penetrates through the inner-ring mixing pipe; and the multiple inner ring fuel gas and flue gas mixing ejectors are arranged at intervals in the circumferential direction of the air sleeve. And nitrogen oxide emission can be controlled, and stable combustion is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of gas burners, and in particular relates to a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion. Background Art

[0002] Boiler air pollutant emission standards for nitrogen oxides (NO x ) The tightening of emission limits has made low-nitrogen combustion technology a hot topic in industry research. The emission of nitrogen oxides not only causes serious pollution to the atmospheric environment, but also has a negative impact on public health. Therefore, the research and development of gas burners with both low nitrogen emissions and efficient combustion has become an urgent task facing the current energy industry.

[0003] Although low-nitrogen burners in the existing technology can reduce nitrogen oxide emissions to a certain extent, they often sacrifice combustion efficiency, resulting in a decrease in the overall energy efficiency of the equipment and an increase in operating costs. In addition, the complex design structure also increases the difficulty of installation and maintenance, which is not conducive to promotion and popularization in large-scale industrial applications.

[0004] Therefore, there is an urgent need to develop a new type of low-nitrogen burner that can effectively control nitrogen oxide emissions and ensure efficient and stable combustion performance. Summary of the invention

[0005] In view of this, in order to solve the problem that the low-nitrogen burner in the prior art cannot guarantee both effective control of nitrogen oxide emissions and efficient and stable combustion performance, the present invention proposes a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, comprising:

[0008] An air channel, an air sleeve and a duty sleeve, wherein the outlet end of the air channel is penetrated through the air sleeve, the inlet end of the duty sleeve is penetrated through the air sleeve, the inlet of the air sleeve is a central smoke entrainment port, and the diameter of the central smoke entrainment port is greater than the diameter of the outlet of the air channel;

[0009] A first swirl blade is provided on the air sleeve and is located between the outlet end of the air passage and the inlet end of the duty sleeve;

[0010] A second swirl blade is arranged on the duty sleeve;

[0011] A duty flame gas pipe, the duty flame gas pipe is sequentially passed through the air passage, the air sleeve and the duty sleeve, and an injection hole group is provided at the outlet end of the duty flame gas pipe;

[0012] A plurality of outer ring gas and smoke mixing injectors, including an outer ring main flame gas pipe and an outer ring mixing pipe, wherein the outlet end of the outer ring main flame gas pipe is penetrated through the outer ring mixing pipe, and the diameter of the inlet of the outer ring mixing pipe is larger than the diameter of the outlet of the outer ring main flame gas pipe; the plurality of outer ring gas and smoke mixing injectors are arranged at intervals along the circumferential direction of the air sleeve;

[0013] A plurality of inner circle gas and smoke mixing injectors include an inner circle main flame gas pipe and an inner circle mixing pipe, wherein the outlet end of the inner circle main flame gas pipe is penetrated through the inner circle mixing pipe, and the diameter of the inlet of the inner circle mixing pipe is larger than the diameter of the outlet of the inner circle main flame gas pipe; the plurality of inner circle gas and smoke mixing injectors are arranged at intervals along the circumferential direction of the air sleeve; the inner circle gas and smoke mixing injectors are located between the outer circle gas and smoke mixing injectors and the air sleeve.

[0014] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, the length of the inner ring mixing tube is smaller than the length of the outer ring mixing tube, and the outlet of the inner ring mixing tube is farther away from the outlet of the duty sleeve relative to the outlet of the outer ring mixing tube.

[0015] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, a plurality of the inner ring gas-flue gas mixing injectors and a plurality of the outer ring gas-flue gas mixing injectors are arranged alternately.

[0016] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, the outlet end of the outer ring mixing tube and the outlet end of the inner ring mixing tube are both provided with a bevel angle.

[0017] As a preferred solution of the above-mentioned low-nitrogen gas burner with coupled flue gas recirculation and staged combustion, the inlet end of the inner ring mixing tube is provided with an inner ring flue gas entrainment expansion port; the inlet end of the outer ring mixing tube is provided with an outer ring flue gas entrainment expansion port.

[0018] As a preferred solution of the above-mentioned low-nitrogen gas burner with flue gas recirculation and staged combustion coupling, the inner ring mixing tube is provided with a plurality of inner ring flue gas entrainment rectangular holes arranged at intervals along the circumferential direction; the outer ring mixing tube is provided with a plurality of outer ring flue gas entrainment rectangular holes arranged at intervals along the circumferential direction.

[0019] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, the injection hole group includes a duty flame radial injection hole and a duty flame axial injection hole, and the duty flame axial injection hole is arranged on the end face of the outlet end of the duty flame gas pipe; the duty flame gas pipe is fixed with a duty flame branch pipe, and the duty flame radial injection holes are arranged on the circumferential surface of the duty flame branch pipe.

[0020] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, the inlet end of the duty sleeve is provided with a duty sleeve expansion.

[0021] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, an air channel expansion is provided at the outlet end of the air channel.

[0022] As a preferred solution of the above-mentioned low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, an air sleeve expansion port is provided at the outlet end of the air sleeve.

[0023] Compared with the prior art, the low-nitrogen gas burner coupled with flue gas recirculation and staged combustion provided by the present invention has the following beneficial effects:

[0024] The present invention provides a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion inhales flue gas through high-speed air rolls at the central flue gas suction port, and inhales flue gas through high-speed gas rolls at the inner and outer circle smoke suction expansion ports and the inner and outer circle smoke suction rectangular holes, so that the flue gas circulates in the burner. Due to the mixing of flue gas, the oxygen concentration can be reduced, heat can be absorbed, and thus the combustion speed and temperature can be reduced, thereby achieving the purpose of inhibiting the generation of nitrogen oxides. Moreover, the fuel gas is divided into duty fuel gas and double-layer staggered main flame fuel gas, which enter the furnace successively to complete the staged combustion of the fuel, so that the fuel gas is burned in different combustion areas, the combustion speed and temperature level can be controlled, and the thermal NO x The generation of the mixed gas of air and smoke can ensure efficient and stable combustion performance. In addition, the mixed gas of air and smoke passes through the first swirl blade and the second swirl blade successively, and has a certain swirl intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a structural schematic diagram of a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion provided by a specific embodiment of the present invention;

[0027] Figure 2 It is a side view of a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion provided by a specific embodiment of the present invention.

[0028] In the figure:

[0029] 1. Air channel; 11. Air channel expansion;

[0030] 2. Air sleeve; 21. Air sleeve expansion; 22. Central smoke suction port;

[0031] 3. Duty sleeve; 31. Duty sleeve expansion;

[0032] 4. The first swirl blade;

[0033] 5. Second swirl blade;

[0034] 6. Duty flame gas pipe; 61. Duty flame branch pipe; 62. Duty flame axial injection hole;

[0035] 7. Outer ring gas and smoke mixing injector; 71. Outer ring main flame gas pipe; 72. Outer ring mixing pipe; 721. Outer ring smoke entrainment expansion; 722. Outer ring smoke entrainment rectangular hole;

[0036] 8. Inner circle gas and smoke mixing injector; 81. Inner circle main flame gas pipe; 82. Inner circle mixing pipe; 821. Inner circle smoke entrainment expansion opening; 822. Inner circle smoke entrainment rectangular hole. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0038] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0040] In the description of this embodiment, the terms "upper", "lower", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0041] See also Figure 1 and Figure 2Description of this embodiment. The present invention provides a low-nitrogen gas burner coupled with flue gas recirculation and staged combustion. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion comprises an air channel 1, an air sleeve 2, a duty sleeve 3, a first swirl blade 4, a second swirl blade 5, a duty flame gas pipe 6, a plurality of outer ring gas and flue gas mixing injectors 7 and a plurality of inner ring gas and flue gas mixing injectors 8. The outlet end of the air channel 1 is penetrated in the air sleeve 2, and the inlet end of the duty sleeve 3 is penetrated in the air sleeve 2. The inlet of the air sleeve 2 is a central flue gas entrainment port 22, and the diameter of the central flue gas entrainment port 22 is greater than the diameter of the outlet of the air channel 1; the first swirl blade 4 is arranged in the air sleeve 2, and is located between the outlet end of the air channel 1 and the inlet end of the duty sleeve 3; the second swirl blade 5 is arranged in the duty sleeve 3; the duty flame gas pipe 6 is sequentially penetrated in the air channel 1, the air sleeve 2 and the duty sleeve Tube 3, the outlet end of the duty flame gas pipe 6 is provided with a spray hole group; the outer ring gas and smoke mixing injector 7 includes an outer ring main flame gas pipe 71 and an outer ring mixing pipe 72, the outlet end of the outer ring main flame gas pipe 71 is arranged in the outer ring mixing pipe 72, and the diameter of the inlet of the outer ring mixing pipe 72 is larger than the diameter of the outlet of the outer ring main flame gas pipe 71; multiple outer ring gas and smoke mixing injectors 7 are arranged at intervals along the circumferential direction of the air sleeve 2; the inner ring gas and smoke mixing injector 8 includes an inner ring main flame gas pipe 81 and an inner ring mixing pipe 82, the outlet end of the inner ring main flame gas pipe 81 is arranged in the inner ring mixing pipe 82, and the diameter of the inlet of the inner ring mixing pipe 82 is larger than the diameter of the outlet of the inner ring main flame gas pipe 81; multiple inner ring gas and smoke mixing injectors 8 are arranged at intervals along the circumferential direction of the air sleeve 2; the inner ring gas and smoke mixing injector 8 is located between the outer ring gas and smoke mixing injector 7 and the air sleeve 2.

[0042] It can be understood that the inlet of the air sleeve 2 is the central smoke suction port 22, and the diameter of the central smoke suction port 22 is larger than the diameter of the outlet of the air channel 1. Then, there is a channel between the inner wall of the central smoke suction port 22 and the outer wall of the air channel 1, and the smoke can enter the air sleeve 2 through the channel, and the smoke and air are mixed in the air sleeve 2.

[0043] It can be understood that if the diameter of the inlet of the outer ring mixing tube 72 is larger than the diameter of the outlet of the outer ring main flame gas tube 71, there is a channel between the inner wall of the outer ring mixing tube 72 and the outer wall of the outer ring main flame gas tube 71, and the smoke can enter the outer ring mixing tube 72 through the channel, and the smoke and the gas are mixed in the outer ring mixing tube 72. If the diameter of the inlet of the inner ring mixing tube 82 is larger than the diameter of the outlet of the inner ring main flame gas tube 81, there is a channel between the inner wall of the inner ring mixing tube 82 and the outer wall of the inner ring main flame gas tube 81, and the smoke can enter the inner ring mixing tube 82 through the channel, and the smoke and the gas are mixed in the inner ring mixing tube 82.

[0044] The above-mentioned flue gas is the flue gas generated after combustion in the furnace, and a recirculation zone is formed in the furnace. The flue gas can be sucked into the air sleeve 2 by the central flue gas suction port 22, and can also be sucked into the inlet of the inner ring mixing tube 82 and the inlet of the outer ring mixing tube 72.

[0045] When the low-nitrogen gas burner coupled with flue gas recirculation and staged combustion is working, air enters the air sleeve 2 through the air channel 1, and the reflux flue gas is sucked into the air sleeve 2 from the central flue gas entrainment port 22. The flue gas and air both enter the first swirl blade 4, and the air and flue gas are fully mixed by the first swirl blade 4. Then, a part of the mixed gas is sprayed into the furnace from the outlet of the air sleeve 2, which reduces the oxygen concentration in the mixed gas and inhibits the generation of nitrogen oxides. At the same time, the mixed gas has a certain swirl intensity, which can be quickly mixed with the fuel and form a stable combustion area; the other part of the mixed gas enters the duty sleeve 3 from the air sleeve 2, passes through the second swirl blade 5, and is sprayed into the furnace from the outlet of the duty sleeve 3. After passing through the second swirl blade 5, the mixed gas of air and flue gas has a swirl intensity, which can be quickly mixed with the gas, increasing the mixing uniformity and ensuring the ignition and combustion stability. The gas is sprayed into the furnace from the injection hole group of the duty flame gas pipe 6. The fuel gas is directly sprayed into the inner circle mixing tube 82 and the outer circle mixing tube 72 from the inner circle main flame fuel gas pipe 81 and the outer circle main flame fuel gas pipe 71 respectively. The high-temperature and high-speed fuel gas entrains the reflux flue gas, and the flue gas produced by the combustion is re-sucked into the inner circle mixing tube 82 and the outer circle mixing tube 72. The fuel gas and the flue gas are mixed and sprayed into the furnace, and the flue gas produced by the combustion is re-sucked into the combustion area, which acts as a heat absorber, reduces the flame temperature in the high-temperature zone, and reduces the emission of nitrogen oxides.

[0046] The low-nitrogen gas burner with flue gas recirculation and staged combustion coupling is mainly used for medium and small gas boilers equipped with a gas combustion system, and integrates the flue gas recirculation technology and the fuel staging technology. The return flue gas is sucked in through the injection of gas and air, so that the flue gas circulates in the burner. The flue gas recirculation technology effectively reduces the oxygen concentration of the mixed gas and reduces the flame temperature in the high-temperature area. At the same time, the gas is supplied from the duty flame gas pipe 6, the inner circle main flame gas pipe 81 and the outer circle main flame gas pipe 71 to achieve fuel staging. The fuel staging technology effectively improves the flame dispersion, makes the combustion temperature lower and more uniform, reduces the local high-temperature area, and thus inhibits nitrogen oxides (NO x ) and ensure efficient and stable combustion performance.

[0047] In this embodiment, the outlet of the outer circle main flame gas pipe 71 and the outlet of the inner circle main flame gas pipe 81 are both provided with main flame straight outlets, and the gas outlet jetting speed is increased by jetting through the main flame straight outlets.

[0048] In this embodiment, the air sleeve 2 is a streamlined structure, which can make the air flow velocity field uniform and ensure stable combustion under low load conditions.

[0049] Optionally, the length of the inner mixing tube 82 is smaller than that of the outer mixing tube 72, and the outlet of the inner mixing tube 82 is farther away from the outlet of the duty sleeve 3 than the outlet of the outer mixing tube 72. The outlet of the inner mixing tube 82 can spray out the mixed gas of flue gas and fuel gas first, and the outlet of the outer mixing tube 72 can spray out the mixed gas of flue gas and fuel gas later, and the mixed gas of the inner and outer ring fuel gas and the entrained flue gas is sprayed out with a time difference, thereby avoiding flame concentration.

[0050] Optionally, multiple inner ring gas and smoke mixing injectors 8 and multiple outer ring gas and smoke mixing injectors 7 are arranged in a staggered manner. Multiple inner ring gas and smoke mixing injectors 8 and multiple outer ring gas and smoke mixing injectors 7 are arranged in two inner and outer rings and staggered, which can disperse the flame and avoid flame concentration.

[0051] Optionally, the outlet end of the outer mixing tube 72 and the outlet end of the inner mixing tube 82 are both provided with a bevel angle. This will further improve the flame dispersion, make the temperature field uniform, reduce the local high temperature area, and thus inhibit the generation of nitrogen oxides. In this embodiment, the long end of the bevel angle at the outlet end of the outer mixing tube 72 is close to the inner mixing tube 82, and the long end of the bevel angle at the outlet end of the inner mixing tube 82 is close to the outer mixing tube 72.

[0052] In this embodiment, the bevel angle is 45°.

[0053] Optionally, the inlet end of the inner mixing tube 82 is provided with an inner smoke entrainment expansion port 821, and the inlet end of the outer mixing tube 72 is provided with an outer smoke entrainment expansion port 721. This can increase the intake volume of the reflux smoke.

[0054] Optionally, the inner ring mixing tube 82 is provided with a plurality of inner ring smoke entrainment rectangular holes 822 spaced apart along the circumferential direction; the outer ring mixing tube 72 is provided with a plurality of outer ring smoke entrainment rectangular holes 722 spaced apart along the circumferential direction. The plurality of inner ring smoke entrainment rectangular holes 822 are arranged at the tapering section of the inner ring mixing tube 82. The plurality of outer ring smoke entrainment rectangular holes 722 are arranged at the tapering section of the outer ring mixing tube 72. Smoke can also be entrained into the inner ring mixing tube 82 and the outer ring mixing tube 72 from the inner ring entrainment rectangular holes and the outer ring entrainment rectangular holes, respectively. By entraining the reflux smoke through the inner ring entrainment rectangular holes and the outer ring entrainment rectangular holes, the resistance loss when the gas enters can be reduced.

[0055] Optionally, the injection hole group includes a duty flame radial injection hole and a duty flame axial injection hole 62, and the duty flame axial injection hole 62 is arranged on the end face of the outlet end of the duty flame gas pipe 6; the duty flame gas pipe 6 is fixed with a duty flame branch pipe 61, and the duty flame radial injection holes are arranged on the circumference of the duty flame branch pipe 61. The duty flame axial injection hole 62 sprays the gas axially, and the duty flame radial injection hole sprays the gas radially. The gas is sprayed successively by multiple duty flame axial injection holes 62 and multiple duty flame radial injection holes on the duty flame branch pipe 61 to form a diffusion flame to prevent the generation of local high temperature of the flame. It can be understood that the injection direction of the duty flame axial injection hole 62 is centripetal injection.

[0056] Optionally, the inlet end of the duty sleeve 3 is provided with a duty sleeve flare 31. The duty sleeve flare 31 increases the airflow entering the duty sleeve 3, increases the airflow outlet velocity, and reduces the risk of flashback.

[0057] Optionally, the outlet end of the air channel 1 is provided with an air channel expansion opening 11. Optionally, the outlet end of the air sleeve 2 is provided with an air sleeve expansion opening 21.

[0058] Obviously, the embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A low-nitrogen gas burner coupled with flue gas recirculation and staged combustion, characterized in that: include: An air channel (1), an air sleeve (2) and a duty sleeve (3), wherein the outlet end of the air channel (1) is penetrated through the air sleeve (2), the inlet end of the duty sleeve (3) is penetrated through the air sleeve (2), the inlet of the air sleeve (2) is a central smoke entrainment port (22), and the diameter of the central smoke entrainment port (22) is greater than the diameter of the outlet of the air channel (1); A first swirl blade (4) is arranged on the air sleeve (2) and is located between the outlet end of the air passage (1) and the inlet end of the duty sleeve (3); A second swirl blade (5) is arranged on the duty sleeve (3); A duty flame gas pipe (6), the duty flame gas pipe (6) is sequentially inserted into the air passage (1), the air sleeve (2) and the duty sleeve (3), and a spray hole group is provided at the outlet end of the duty flame gas pipe (6); A plurality of outer ring gas and smoke mixing injectors (7) comprise an outer ring main flame gas pipe (71) and an outer ring mixing pipe (72); the outlet end of the outer ring main flame gas pipe (71) is arranged through the outer ring mixing pipe (72); the diameter of the inlet of the outer ring mixing pipe (72) is larger than the diameter of the outlet of the outer ring main flame gas pipe (71); the plurality of outer ring gas and smoke mixing injectors (7) are arranged at intervals along the circumferential direction of the air sleeve (2); A plurality of inner ring gas and smoke mixing injectors (8) comprise an inner ring main flame gas pipe (81) and an inner ring mixing pipe (82); the outlet end of the inner ring main flame gas pipe (81) is arranged through the inner ring mixing pipe (82); the diameter of the inlet of the inner ring mixing pipe (82) is larger than the diameter of the outlet of the inner ring main flame gas pipe (81); the plurality of inner ring gas and smoke mixing injectors (8) are arranged at intervals along the circumferential direction of the air sleeve (2); the inner ring gas and smoke mixing injectors (8) are located between the outer ring gas and smoke mixing injectors (7) and the air sleeve (2).

2. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1 is characterized in that: The length of the inner ring mixing tube (82) is smaller than the length of the outer ring mixing tube (72), and the outlet of the inner ring mixing tube (82) is farther away from the outlet of the duty sleeve (3) relative to the outlet of the outer ring mixing tube (72).

3. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1 is characterized in that: The plurality of inner ring fuel gas and fume mixing injectors (8) and the plurality of outer ring fuel gas and fume mixing injectors (7) are arranged in a staggered manner.

4. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1 is characterized in that: The outlet end of the outer ring mixing tube (72) and the outlet end of the inner ring mixing tube (82) are both provided with a bevel angle.

5. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1 is characterized in that: The inlet end of the inner ring mixing tube (82) is provided with an inner ring smoke entrainment expansion opening (821); the inlet end of the outer ring mixing tube (72) is provided with an outer ring smoke entrainment expansion opening (721).

6. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1, characterized in that: The inner ring mixing tube (82) is provided with a plurality of inner ring smoke entrainment rectangular holes (822) spaced apart along the circumferential direction; the outer ring mixing tube (72) is provided with a plurality of outer ring smoke entrainment rectangular holes (722) spaced apart along the circumferential direction.

7. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1, characterized in that: The injection hole group comprises a duty flame radial injection hole and a duty flame axial injection hole (62), wherein the duty flame axial injection hole (62) is arranged on the end face of the outlet end of the duty flame gas pipe (6); the duty flame gas pipe (6) is fixedly provided with a duty flame branch pipe (61), and the duty flame radial injection hole is arranged on the circumferential surface of the duty flame branch pipe (61).

8. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1, characterized in that: The inlet end of the duty sleeve (3) is provided with a duty sleeve expansion opening (31).

9. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1, characterized in that: The outlet end of the air channel (1) is provided with an air channel expansion opening (11).

10. The low-nitrogen gas burner coupled with flue gas recirculation and staged combustion according to claim 1, characterized in that: The outlet end of the air sleeve (2) is provided with an air sleeve expansion opening (21).

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