Multi-injection graded low-nitrogen gas burner

Abstract

The invention discloses a multi-injection graded low-nitrogen gas burner, and relates to a low-nitrogen gas burner. The problems that an existing gas burner is not uniform enough in fuel injection and high in thermal NOx emission are solved. The multi-injection dispersed combustion technology and the flue gas recirculation technology are organically combined, that is, the radial gas injection openings and the porous swirl vanes arranged on the on-duty gas pipe achieve on-duty gas multi-injection, uniform distribution of the gas in a combustion area is achieved, and meanwhile efficient mixing of air and the gas is guaranteed. And secondly, the venturi tube can entrain the backflow flue gas in the hearth, so that the fuel gas and the flue gas enter the fuel gas mixing tube through the mixing tube flaring and the mixing tube entrainment port and then are sprayed into the hearth to form flue gas backflow, and the oxygen concentration and the absorbed heat in a combustion area are effectively reduced, so that the combustion temperature is reduced, and the generation of thermal NOx is reduced. The invention belongs to the technical field of boiler combustion devices.

Description

Technical Field

[0001] The invention relates to a gas burner, in particular to a multi-injection staged low-nitrogen gas burner, belonging to the technical field of boiler combustion devices. Background Art

[0003] Existing gas burners mostly use the traditional nozzle gas injection method. The fuel injection is not uniform enough, resulting in serious local high temperature phenomenon, which promotes the generation of thermal NOx and further causes the emission of thermal NOx to remain high.

[0004] In summary, how to propose a new low-nitrogen gas burner to address the above technical problems has become an urgent problem to be solved by technicians in this field. Summary of the invention

[0005] The present invention aims at solving the above-mentioned deficiencies of the prior art and further provides a multi-injection staged low-nitrogen gas burner.

[0006] The technical solution of the present invention is: a multi-injection graded low-nitrogen gas burner, comprising a duty gas pipe, a central air inlet pipe, a duty sleeve, a venturi tube, a plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles.

[0007] A plurality of radial gas injection ports are provided at the outlet of the duty gas pipe in a circumferential array, and a plurality of porous swirl blades are fixedly connected to the duty gas pipe in a circumferential array.

[0008] A plurality of axial gas injection holes are opened on the backflow side of the porous swirl blade, and an L-shaped gas branch pipe is installed on the frontflow side of the porous swirl blade. Both ends of the L-shaped gas branch pipe are respectively connected to the duty gas pipe and the axial gas injection hole.

[0009] The central air inlet pipe, the outer circle main flame nozzle and the inner circle main flame nozzle are all fixedly connected to the furnace wall.

[0010] The central air inlet pipe and the duty sleeve are sequentially sleeved on the duty gas pipe according to the direction of airflow injection, the venturi tube is coaxially sleeved on the duty sleeve, and the outlet of the central air inlet pipe is inserted into the inlet of the venturi tube.

[0011] A plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles are arranged around the central air inlet pipe in a circular array, and the outer ring main flame nozzles are arranged on a circle with a diameter of D1, and the inner ring main flame nozzles are arranged on a circle with a diameter of D2, D1>D2.

[0012] The outer circle main flame nozzle and the inner circle main flame nozzle both include a main flame fuel gas pipe, a mixing pipe expansion port and a fuel gas mixing pipe.

[0013] The outlet of the main flame gas pipe is inserted into the inlet of the gas mixing pipe, the expanded small end of the mixing pipe is fixedly connected to the inlet of the gas mixing pipe, the gas mixing pipe is provided with a mixing pipe suction port, and the nozzle of the gas mixing pipe is an oblique nozzle.

[0014] The bevel angle of the gas mixing pipe in the outer circle main flame nozzle is away from the venturi tube, and the bevel angle of the gas mixing pipe in the inner circle main flame nozzle is toward the venturi tube.

[0015] Compared with the prior art, the present invention has the following effects:

[0016] The present invention organically combines the multi-injection dispersed combustion technology and the flue gas recirculation technology to achieve a stable and low-pollution combustion process, namely:

[0017] Multiple injections of the duty gas are achieved through the radial gas injection ports 17 and the porous swirl blades 18 arranged on the duty gas pipe 1, thereby achieving uniform distribution of the gas in the combustion area and ensuring efficient mixing of air and gas, thereby suppressing the generation of thermal NOx and significantly reducing pollutant emissions while meeting the requirements of efficient combustion.

[0018] Secondly, the venturi tube 6 can entrain the reflux flue gas in the furnace, so that the fuel gas and the flue gas enter the fuel gas mixing tube 13 through the mixing tube expansion port 11 and the mixing tube entrainment port 12, and then spray into the furnace to form flue gas reflux. This reflux flue gas effectively reduces the oxygen concentration in the combustion area, absorbs heat, thereby reducing the combustion temperature and reducing the generation of thermal NOx. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the arrangement of the duty gas pipe 1, the L-shaped gas branch pipe 15 and the porous swirl blades 18 of the present invention;

[0021] Figure 3 It is a front view of the present invention;

[0022] Figure 4 is a schematic diagram of flame and smoke in a furnace when the present invention is used;

[0023] In the figure: 1. duty gas pipe; 2. central air inlet pipe; 3. duty sleeve contraction; 4. duty sleeve; 5. duty sleeve expansion; 6. Venturi tube; 7. Venturi suction port; 8. Venturi expansion; 9. main flame gas pipe; 10. main flame gas contraction; 11. mixing tube expansion; 12. mixing tube suction port; 13. gas mixing tube; 15. L-shaped gas branch pipe; 16. axial gas injection hole; 17. radial gas injection hole; 18. porous swirl blade. DETAILED DESCRIPTION

[0024] In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solution in this embodiment will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0025] Specific implementation method 1: Combination Figures 1 to 4 To illustrate the present embodiment, a multi-injection staged low-nitrogen gas burner of the present embodiment includes a service gas pipe 1, a central air inlet pipe 2, a service sleeve 4, a venturi tube 6, a plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles.

[0026] A number of radial gas injection ports 17 are provided at the outlet of the duty gas pipe 1 in a circular array. Each radial gas injection port 17 injects gas evenly into the furnace to form a more dispersed gas injection flow. Therefore, the gas can be more evenly distributed in the combustion area and fully mixed with the air for combustion, thus avoiding local overheating caused by uneven gas injection in traditional burners.

[0027] A plurality of porous swirl blades 18 are fixedly connected to the duty gas pipe 1 in a circumferential array. A plurality of axial gas injection holes 16 are opened on the backflow side of the porous swirl blade 18. An L-shaped gas branch pipe 15 is installed on the frontflow side of the porous swirl blade 18. The two ends of the L-shaped gas branch pipe 15 are respectively connected to the duty gas pipe 1 and the axial gas injection holes 16. Part of the duty gas in the duty gas pipe 1 enters the hollow porous swirl blade 18 through the L-shaped gas branch pipe 15, and is then ejected from the multiple axial gas injection holes 16 on the blade, which can effectively diffuse the ejected gas flow and fully mix it with the air, so as to realize multiple injections of the gas in the duty gas pipe 1 through the axial gas injection holes 16 and the radial gas injection ports 17.

[0028] The central air inlet pipe 2, the outer circle main flame nozzle and the inner circle main flame nozzle are all fixedly connected to the furnace wall.

[0029] The central air inlet pipe 2 and the duty sleeve 4 are sequentially sleeved on the duty gas pipe 1 according to the direction of airflow injection, and the inner circumference of the central air inlet pipe 2 and the outer circumference of the duty gas pipe 1 form an air channel. The venturi tube 6 is coaxially sleeved on the duty sleeve 4, and the outlet of the central air inlet pipe 2 is inserted into the inlet of the venturi tube 6. In this way, the inlet of the venturi tube 6 can suck the reflux flue gas in the furnace, and part of the flue gas is injected into the furnace through the back of the venturi tube 6, and another part of the flue gas is mixed with the air ejected from the central air inlet pipe 2 and injected into the duty sleeve 4. The mixed gas of air and flue gas has a certain swirl strength after passing through the porous swirl blades 18, which accelerates the mixing speed with the gas, further increases the mixing uniformity, forms a diffusion flame, and reduces the generation of thermal NOx.

[0030] A plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles are arranged around the central air inlet pipe 2 in a circular array, and the outer ring main flame nozzles are arranged on a circle with a diameter of D1, and the inner ring main flame nozzles are arranged on a circle with a diameter of D2, D1>D2.

[0031] The outer circle main flame nozzle and the inner circle main flame nozzle both include a main flame gas pipe 9 , a mixing pipe expansion port 11 and a gas mixing pipe 13 .

[0032] The outlet of the main flame gas pipe 9 is inserted into the inlet of the gas mixing pipe 13, the small end of the mixing pipe expansion port 11 is fixedly connected to the inlet of the gas mixing pipe 13, and the gas mixing pipe 13 is provided with a mixing pipe suction port 12. The nozzle of the gas mixing pipe 13 is a bevel nozzle, and further, the bevel angle of the bevel nozzle is 45°.

[0033] The bevel angle of the gas mixing tube 13 in the outer circle main flame nozzle is away from the Venturi tube 6, and the bevel angle of the gas mixing tube 13 in the inner circle main flame nozzle is toward the Venturi tube 6. With this arrangement, the gas discharged from the outer circle main flame nozzle is deflected in the direction away from the Venturi tube 6, and the gas discharged from the inner circle main flame nozzle is deflected in the direction of the Venturi tube 6, which can make the gas evenly distributed in the combustion area, thereby making the main flame fatter and longer in the furnace, improving the combustion efficiency, improving the dispersion of the main flame, reducing local high temperature areas, and reducing the generation of nitrogen oxides.

[0034] Specific implementation method 2: Combination Figures 1 to 4 To explain this embodiment, in this embodiment, the inner circumference of the venturi tube 6 is connected to the outer circumference of the duty gas pipe 1 via ribs, and the venturi tube 6 includes a venturi suction port 7, a throat and a venturi expansion port 8 which are coaxially fixed in sequence.

[0035] Furthermore, the Venturi suction port 7 and the Venturi expansion port 8 are both trumpet-shaped tubes, and the throat is a hollow cylindrical tube. The two ends of the throat are respectively fixedly connected to the small end of the Venturi suction port 7 and the small end of the Venturi expansion port 8. With this arrangement, the Venturi suction port 7 can suck the reflux flue gas in the furnace, mix the flue gas with the air in the Venturi tube 6, and then enter the furnace through the Venturi expansion port 8, so as to reintroduce the flue gas generated after combustion into the combustion area, effectively reduce the oxygen concentration in the combustion area, reduce the combustion temperature, and further reduce the generation of thermal NOx.

[0036] Other components and connection methods are the same as those in the first embodiment.

[0037] Specific implementation method three: Combination Figures 1 to 4 To illustrate this embodiment, the inner circumference of the central air inlet pipe 2 of this embodiment is connected to the outer circumference of the duty gas pipe 1 via ribs, and a tapered pipe with a gradually decreasing diameter is integrally provided at the outlet of the central air inlet pipe 2, and the tapered pipe is inserted into the Venturi suction port 7.

[0038] The other components and connection methods are the same as those in the first and second embodiments.

[0039] Specific implementation method four: Combination Figures 1 to 4 To explain this embodiment, in this embodiment, the inlet of the duty sleeve 4 is coaxially fixedly connected with the duty sleeve contraction 3, and the outlet of the duty sleeve 4 is coaxially fixedly connected with the duty sleeve expansion 5.

[0040] Furthermore, the duty sleeve shrinkage 3 and the duty sleeve expansion 5 are both trumpet-shaped tubes, the duty sleeve 4 is a hollow cylindrical tube, and the two ends of the duty sleeve 4 are respectively fixedly connected to the large end of the duty sleeve shrinkage 3 and the small end of the duty sleeve expansion 5.

[0041] The other components and connection methods are the same as those of the first to third embodiments.

[0042] Specific implementation method five: Combination Figures 1 to 4 This embodiment is described. In this embodiment, the outlet of the main flame gas pipe 9 is integrally provided with a main flame gas reduction port 10 with a gradually reduced diameter, and the main flame gas reduction port 10 is fixedly connected to the gas mixing pipe 13 through a rib plate. In this arrangement, the gas is accelerated when passing through the main flame gas reduction port 10, and the gas entrains the reflux flue gas in the furnace, so that the gas and flue gas enter the gas mixing pipe 13 through the mixing pipe expansion port 11 and the mixing pipe entrainment port 12, and then are sprayed into the furnace, so that the flue gas can absorb heat, reduce the flame temperature, and further reduce the generation of thermal NOx.

[0043] The other components and connection methods are the same as those of the first to fourth embodiments.

[0044] Specific implementation method six: Combination Figures 1 to 4 To explain this embodiment, the number of the outer ring main flame nozzles and the number of the inner ring main flame nozzles in this embodiment are both 6. Other components and connection methods are the same as those in the first to fifth embodiments.

[0045] How it works

[0046] The outlet of the duty gas pipe 1 is provided with a radial gas injection port 17, which uniformly injects gas into the furnace, so that the gas can be more evenly distributed in the combustion area and fully mixed with the air for combustion; secondly, a plurality of porous swirl blades 18 are fixedly connected to the duty gas pipe 1, and a plurality of axial gas injection holes 16 are provided on the backflow side of the porous swirl blade 18, and an L-shaped gas branch pipe 15 is installed on the frontflow side of the porous swirl blade 18, and the two ends of the L-shaped gas branch pipe 15 are respectively connected to the duty gas pipe 1 and the axial gas injection holes 16. Part of the duty gas in the duty gas pipe 1 enters the hollow porous swirl blade 18 through the L-shaped gas branch pipe 15, and is then ejected from the multiple axial gas injection holes 16 on the blade, which can effectively diffuse the ejected gas flow and fully mix it with the air, so as to realize multiple injections of the gas in the duty gas pipe 1 through the axial gas injection holes 16 and the radial gas injection ports 17.

[0047] The central air inlet pipe 2 and the duty sleeve 4 are sequentially sleeved on the duty gas pipe 1 according to the direction of airflow injection. The venturi tube 6 is coaxially sleeved on the duty sleeve 4. The outlet of the central air inlet pipe 2 is inserted into the inlet of the venturi tube 6 to realize the inlet of the venturi tube 6 to suck the reflux flue gas in the furnace. A part of the flue gas is sprayed into the furnace through the back of the venturi tube 6. After the flue gas is reintroduced into the combustion area, the oxygen concentration in the combustion area is effectively reduced, the combustion temperature is reduced, and the generation of thermal NOx is further reduced; another part of the flue gas is mixed with the air sprayed from the central air inlet pipe 2 and is injected into the duty sleeve 4. The mixed gas of air and flue gas has a certain swirl intensity after passing through the porous swirl blades 18, which accelerates the mixing speed with the gas, further increases the mixing uniformity, forms a diffusion flame, and reduces the generation of thermal NOx.

[0048] A plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles are arranged around the central air inlet pipe 2 in a circular array, and both the outer ring main flame nozzles and the inner ring main flame nozzles include a main flame gas pipe 9, a mixing pipe expansion 11 and a gas mixing pipe 13, and the nozzle of the gas mixing pipe 13 is a bevel nozzle.

[0049] The bevel angle of the gas mixing tube 13 in the outer circle main flame nozzle is away from the Venturi tube 6, and the bevel angle of the gas mixing tube 13 in the inner circle main flame nozzle is toward the Venturi tube 6. With this arrangement, the gas discharged from the outer circle main flame nozzle is deflected in the direction away from the Venturi tube 6, and the gas discharged from the inner circle main flame nozzle is deflected in the direction of the Venturi tube 6, which can make the gas evenly distributed in the combustion area, thereby making the main flame fatter and longer in the furnace, improving the combustion efficiency, improving the dispersion of the main flame, reducing local high temperature areas, and reducing the generation of nitrogen oxides.

[0050] The present invention has been disclosed as above in the form of a preferred embodiment, but it is not intended to limit the present invention. Any simple modification, equivalent changes and modifications made to the above implementation cases by any professional and technical personnel who do not deviate from the content of the technical solution of the present invention and based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A multi-injection staged low-nitrogen gas burner, characterized in that: It comprises a duty gas pipe (1), a central air inlet pipe (2), a duty sleeve (4), a venturi tube (6), a plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles; A plurality of radial gas injection ports (17) are provided at the outlet of the duty gas pipe (1) in a circumferential array, and a plurality of porous swirl blades (18) are fixedly connected to the duty gas pipe (1) in a circumferential array; The backflow side of the porous swirl blade (18) is provided with a plurality of axial gas injection holes (16), and the frontflow side of the porous swirl blade (18) is provided with an L-shaped gas branch pipe (15), and the two ends of the L-shaped gas branch pipe (15) are respectively connected to the duty gas pipe (1) and the axial gas injection hole (16); The central air inlet pipe (2), the outer ring main flame nozzle and the inner ring main flame nozzle are all fixedly connected to the furnace wall; The central air inlet pipe (2) and the duty sleeve (4) are sequentially sleeved on the duty gas pipe (1) according to the direction of airflow injection, the venturi tube (6) is coaxially sleeved on the duty sleeve (4), and the outlet of the central air inlet pipe (2) is inserted into the inlet of the venturi tube (6); A plurality of outer ring main flame nozzles and a plurality of inner ring main flame nozzles are arranged around the central air inlet pipe (2) in a circular array, and the outer ring main flame nozzles are arranged on a circle with a diameter of D1, and the inner ring main flame nozzles are arranged on a circle with a diameter of D2, where D1>D2; The outer circle main flame nozzle and the inner circle main flame nozzle both include a main flame fuel gas pipe (9), a mixing pipe expansion port (11) and a fuel gas mixing pipe (13); The outlet of the main flame gas pipe (9) is inserted into the inlet of the gas mixing pipe (13), the small end of the mixing pipe expansion port (11) is fixedly connected to the inlet of the gas mixing pipe (13), the gas mixing pipe (13) is provided with a mixing pipe suction port (12), and the nozzle of the gas mixing pipe (13) is an oblique nozzle; The bevel angle of the gas mixing pipe (13) in the outer main flame nozzle faces away from the venturi tube (6), while the bevel angle of the gas mixing pipe (13) in the inner main flame nozzle faces toward the venturi tube (6).

2. A multi-injection staged low-nitrogen gas burner according to claim 1, characterized in that: The inner circumferential surface of the Venturi tube (6) is connected to the outer circumferential surface of the duty gas pipe (1) via ribs, and the Venturi tube (6) comprises a Venturi suction port (7), a throat pipe and a Venturi expansion port (8) which are coaxially fixed in sequence.

3. A multi-injection staged low-nitrogen gas burner according to claim 2, characterized in that: The inner circumference of the central air inlet pipe (2) is connected to the outer circumference of the duty gas pipe (1) via ribs, and a tapered pipe with a gradually decreasing diameter is integrally provided at the outlet of the central air inlet pipe (2), and the tapered pipe is inserted into the Venturi suction port (7).

4. A multi-injection staged low-nitrogen gas burner according to claim 3, characterized in that: The inlet of the duty sleeve (4) is coaxially fixedly connected with a duty sleeve shrinkage (3), and the outlet of the duty sleeve (4) is coaxially fixedly connected with a duty sleeve expansion (5).

5. A multi-injection staged low-nitrogen gas burner according to claim 4, characterized in that: The duty sleeve shrinkage (3) and the duty sleeve expansion (5) are both trumpet-shaped tubes, the duty sleeve (4) is a hollow cylindrical tube, and the two ends of the duty sleeve (4) are respectively fixedly connected to the large end of the duty sleeve shrinkage (3) and the small end of the duty sleeve expansion (5).

6. A multi-injection staged low-nitrogen gas burner according to claim 5, characterized in that: A main flame gas constriction (10) with a gradually decreasing diameter is integrally provided at the outlet of the main flame gas pipe (9), and the main flame gas constriction (10) is fixedly connected to the gas mixing pipe (13) via a rib plate.

7. A multi-injection staged low-nitrogen gas burner according to claim 6, characterized in that: The number of the outer ring main flame nozzles and the number of the inner ring main flame nozzles are both 6.

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