A flame splitting high-speed low-nitrogen burner and combustion method thereof

Abstract

The present invention discloses a flame-segmented high-speed low-nitrogen burner, which comprises an air box, wherein a flame generating device is arranged in the air box, a gas box is arranged on the air box, the gas box is connected with the air box through a plurality of first spray holes, a contraction flow channel is arranged at the port of the air box, a plurality of gas pipelines are evenly arranged around the outer side of the contraction flow channel, the gas pipelines are connected with the gas box, a nozzle inclined to the contraction flow channel is arranged at the front end of the gas pipeline, a plurality of dividing bricks are arranged in the outer gap of the contraction flow channel, a dividing plate is arranged on the dividing bricks, and the plurality of dividing plates are respectively arranged between two adjacent nozzles; the flame sprayed by the burner of this scheme can be divided and folded in radial and circumferential directions to form a petal-like flame, so that the temperature distribution of the flame is more uniform, and at the same time, the folded flame surface can make the flue gas reflux, thereby deeply reducing the generation of nitrogen oxides.

Description

Technical Field

[0001] The invention relates to the technical field of burners, and in particular to a flame-segmented high-speed low-nitrogen burner and a combustion method thereof. Background Art

[0002] At present, the domestic industrial burners have a simple structure and low level of organizational combustion technology. They mainly rely on radiation for heat exchange, have low energy utilization, are prone to local high temperatures, and most of the heat is discharged with the flue gas. Among them, nitrogen oxide emissions are generally greater than 100mg / Nm 3 (8% base oxygen content), especially for furnace temperatures greater than 1200°C, nitrogen oxides are generally greater than 150mg / Nm 3 Even higher, mainly because the higher the combustion temperature, the more rapidly the generation rate of thermal nitrogen oxides increases. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a flame-segmented high-speed low-nitrogen burner and a combustion method thereof, which solve the problems of uneven burner temperature distribution and high nitrogen oxide emissions in the prior art.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A flame-segmented high-speed low-nitrogen burner is provided, which comprises an air box, a flame generating device is arranged in the air box, a gas box is arranged on the air box, the gas box is connected to the air box through a plurality of first spray holes, a contraction flow channel is arranged at the port of the air box, a plurality of gas pipelines are evenly arranged around the outside of the contraction flow channel, the gas pipelines are connected to the gas box, a nozzle inclined to the contraction flow channel is arranged at the front end of the gas pipeline, a plurality of dividing bricks are arranged in the gap on the outer wall of the contraction flow channel, a dividing plate is arranged on the dividing bricks, and the plurality of dividing plates are respectively arranged between two adjacent nozzles.

[0006] The beneficial effects of adopting the above technical scheme are as follows: the burner of this scheme forms a stable initial flame through the flame generating device, the initial flame ignites the gas ejected from the first nozzle, and after forming a primary combustion with excess air in the contraction flow channel, it is ejected at high speed through the contraction flow channel and mixed with the gas ejected from the nozzle on the gas pipeline to form a secondary combustion with excess gas, thereby inhibiting the formation of nitrogen oxides. Through the joint action of the dividing bricks and the dividing plates, the ejected flame is divided and folded, so that the temperature distribution of the flame is more uniform.

[0007] Furthermore, the dividing brick is in the shape of an arc-shaped sheet, and the front end of the dividing brick protrudes a port of the contraction flow channel, the dividing plates are respectively arranged on both sides of the outer arc surface of the dividing brick, and the plurality of nozzles include a plurality of first nozzles and a plurality of second nozzles alternately arranged in the circumferential direction, the plurality of first nozzles are respectively arranged between the two dividing plates of the plurality of dividing bricks, and the plurality of second nozzles are respectively arranged between the two dividing plates of two adjacent dividing bricks.

[0008] The beneficial effects of adopting the above technical solution are as follows: the first nozzle and the second nozzle can be divided radially by the dividing bricks, and the first nozzle and the second nozzle can be divided circumferentially by the dividing plate. In this way, the flue gas ejected from the contraction flow channel at high speed is first mixed with the fuel gas ejected from several second nozzles to form a columnar flame, and then mixed with the fuel gas ejected from several first nozzles to form a secondary flame, which wraps the columnar flame and finally forms a secondary combustion with excess fuel gas; at the same time, the dividing plate divides the flame in the circumferential direction, and the divided flames are folded with each other. The folded flame surface can cause the flue gas to reflux, thereby deeply reducing the formation of nitrogen oxides.

[0009] Furthermore, the angle at which the first nozzle is inclined toward the contraction flow channel is smaller than the angle at which the second nozzle is inclined toward the contraction flow channel. This arrangement is beneficial to radial stratification of the secondary combustion flame at the port of the contraction flow channel.

[0010] Furthermore, a second spray hole is arranged inside the gas pipeline provided with the second nozzle, and a plurality of through holes matching the plurality of second spray holes are arranged on the side wall of the contraction flow channel, and the spraying direction of the second spray hole points to the through hole.

[0011] The beneficial effects of adopting the above technical solution are: the gas ejected from the second nozzle enters the contraction flow channel through the through hole on the contraction flow channel to assist combustion, thereby enhancing the ductility, stability and rigidity of the flame in the contraction flow channel, and facilitating the stable ejection of the primary combustion flame from the port of the contraction flow channel.

[0012] Furthermore, the air box is cylindrical, the gas box is sleeved on the outer side wall of the air box, and a plurality of first spray holes are evenly distributed in the circumferential direction of the air box.

[0013] The beneficial effect of adopting the above technical solution is as follows: by evenly distributing a plurality of first spray holes in a circumferential direction of the air box, the fuel gas required for the first-stage combustion is evenly dispersed and sprayed out through the plurality of first spray holes, thereby increasing the contact area between the fuel gas and the air, and contributing to forming the first-stage combustion with excess air. At the same time, the local flame temperature is reduced, and the heat load in the contraction flow channel is evenly distributed.

[0014] Furthermore, the flame generating device includes a central air pipeline, in which a central gas pipeline and an ignition gun are arranged, the ports of the central gas pipeline and the ignition gun are arranged at the ports of the central air pipeline, the ports of the central air pipeline are arranged at the ports of the air box, and an air inlet is arranged on the central air pipeline.

[0015] Furthermore, an air inlet channel and a gas inlet channel are respectively provided on the air box and the gas box, and a plurality of first nozzles are arranged between the air inlet channel and the air box port, so that the gas sprayed from the first nozzles is premixed with the air and then mixed with the flame at the port of the central air pipeline. By controlling the amount of gas and air introduced, primary combustion with excess air can be formed.

[0016] Furthermore, the gas pipeline is wrapped with refractory material to provide thermal protection to prevent high-temperature flames from burning the gas pipeline.

[0017] A combustion method of a flame-segmented high-speed low-nitrogen burner is provided, which comprises the following steps:

[0018] S1: Open the air inlet to introduce air into the port of the central air line;

[0019] S2: Open the central gas pipeline to mix the gas and air at the port of the central air pipeline, and adjust the amount of air introduced into the air inlet to form a mixed gas with an excess air coefficient greater than 1 at the port of the central air pipeline;

[0020] S3: Ignite the mixed gas by using an ignition gun to form a stable flame at the port of the central air pipeline;

[0021] S4: Open the air inlet channel and the gas inlet channel, and the gas sprayed from the first spray hole is pre-mixed with the air in the air box, and then flows to the port of the central air pipeline, and mixes with the flame at the port of the central air pipeline to form a primary combustion with excess air;

[0022] S5: The high-temperature flue gas and excess air generated by the primary combustion are ejected at high speed through the contraction flow channel and mixed with the gas ejected from the second nozzle on the gas pipeline to form the first secondary combustion and eject a cylindrical stable flame;

[0023] S6: The cylindrical stable flame is mixed with the gas ejected from the first nozzle on the gas pipeline to form a second secondary combustion, and a larger columnar flame is formed, which wraps the stable flame formed by the first secondary combustion, thereby forming a secondary combustion with excess gas and ejecting a stable flame with uniform temperature.

[0024] The beneficial effects of the present invention are as follows: the flame ejected by the burner of this scheme can be divided and folded in the radial and circumferential directions to form a petal-shaped flame, making the temperature distribution of the flame more uniform. At the same time, the folded flame surface can cause the flue gas to reflux, thereby deeply reducing the generation of nitrogen oxides; an axial fuel gas staged combustion organization strategy is adopted, and the first-stage combustion adopts a premixed lean combustion method, and the second-stage combustion adopts a diffusion rich combustion method, which helps to reduce the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of a flame-segmented high-speed low-nitrogen burner.

[0026] Figure 2 It is a cross-sectional view of a flame-segmented high-speed low-nitrogen burner.

[0027] Figure 3 This is an end view of a flame-segmented high-velocity, low-nitrogen burner.

[0028] Among them, 1. air box, 2. central air pipeline, 3. central gas pipeline, 4. ignition gun, 5. gas box, 6. first spray hole, 7. contraction flow channel, 8. gas pipeline, 9. dividing brick, 10. dividing plate, 11. first spray port, 12. second spray port, 13. second spray port, 14. through hole, 15. air inlet, 16. air inlet channel, 17. gas inlet channel, 18. annular bracket. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0030] like Figures 1 to 3 As shown, the flame-segmented high-speed low-nitrogen burner of the present scheme includes an air box 1, which is cylindrical with one end open. A central air pipeline 2 is arranged on the axis inside the air box 1, and the central air pipeline 2 is fixed by an annular bracket 18. A central gas pipeline 3 and an ignition gun 4 are arranged in the central air pipeline 2, and the ports of the central gas pipeline 3 and the ignition gun 4 are arranged at the ports of the central air pipeline 2, and the ports of the central air pipeline 2 are arranged at the ports of the air box 1. A gas box 5 is arranged on the outer wall of the air box 1, and the gas box 5 is connected to the air box 1 through a plurality of first spray holes 6, and the plurality of first spray holes 6 are evenly distributed in the circumferential direction of the air box 1.

[0031] A contraction flow channel 7 is provided at the port of the air box 1. The contraction flow channel 7 is in the shape of a truncated cone with openings at both ends. Eight gas pipelines 8 are evenly arranged around the outside of the contraction flow channel 7. The gas pipelines 8 are wrapped with refractory materials to provide thermal protection to prevent high-temperature flames from burning the gas pipelines 8. The gas pipelines 8 are connected to the gas box 5. A nozzle inclined toward the contraction flow channel 7 is provided at the front end of the gas pipeline 8, and the eight nozzles are divided into four first nozzles 11 and four second nozzles 12 alternately arranged in the circumferential direction.

[0032] The burner of the present scheme can form a stable initial flame at the port of the central air pipeline 2. The initial flame ignites the gas ejected from the first nozzle 6, and after forming a primary combustion with excess air in the contraction flow channel 7, it is ejected at high speed through the contraction flow channel 7 and mixed with the gas ejected from the nozzle on the gas pipeline 8 to form a secondary combustion with excess gas, thereby suppressing the formation of nitrogen oxides.

[0033] This scheme adopts the shrinking nozzle technology, and through the shrinking flow channel 7, the high-temperature flue gas after the first-stage combustion is ejected out of the burner at a high speed. The high-speed flue gas can reach more than 100m / s, thereby generating violent disturbances, strengthening convective heat transfer, reducing gas consumption, and improving heating efficiency.

[0034] An air inlet 15, an air inlet channel 16 and a gas inlet channel 17 are respectively provided on the central air pipeline 2, the air box 1 and the gas box 5. A plurality of first spray holes 6 are provided between the air inlet channel 16 and the port of the air box 1, so that the gas sprayed from the first spray holes 6 is premixed with the air and then mixed with the flame at the port of the central air pipeline 2. By controlling the amount of gas and air introduced, primary combustion with excess air can be formed.

[0035] By arranging the central air pipeline 2 at the center of the air box 1 and distributing a plurality of first spray holes 6 evenly around the central air pipeline 2, the fuel gas required for the primary combustion is evenly and dispersedly sprayed out through the plurality of first spray holes 6, thereby increasing the contact area between the fuel gas and the air, and contributing to forming the primary combustion with excess air. At the same time, the local flame temperature is reduced, and the heat load distribution in the contraction flow channel 7 is even.

[0036] Four dividing bricks 9 are arranged in the gap on the outer wall of the contraction flow channel 7. The dividing bricks 9 are in the shape of arcuate sheets, and the front end of the dividing bricks 9 protrudes from the port of the contraction flow channel 7. Dividing plates 10 are arranged on both sides of the outer arc surface of the dividing bricks 9. The four first nozzles 11 are respectively arranged between the two dividing plates 10 of the four dividing bricks 9, and the four second nozzles 12 are respectively arranged between the two dividing plates 10 of two adjacent dividing bricks 9.

[0037] The first nozzle 11 and the second nozzle 12 can be divided radially by the dividing brick 9, and the first nozzle 11 and the second nozzle 12 can be divided circumferentially by the dividing plate 10. This arrangement enables the flue gas ejected at high speed from the contraction flow channel 7 to first mix with the fuel gas ejected from the four second nozzles 12 to form a columnar flame, and then mix with the fuel gas ejected from the four first nozzles 11 to form a secondary flame, which wraps the columnar flame and finally forms a secondary combustion with excess fuel gas. At the same time, the dividing plate 10 divides the flame in the circumferential direction, and the divided flames are folded on each other. This arrangement makes the temperature distribution of the flame more uniform. At the same time, the folded flame surface can cause the flue gas to reflux, thereby deeply reducing the generation of nitrogen oxides.

[0038] The inclination angle of the first nozzle 11 to the contraction flow channel 7 is smaller than the inclination angle of the second nozzle 12 to the contraction flow channel 7 . This arrangement is beneficial to the radial stratification of the secondary combustion flame at the port of the contraction flow channel 7 .

[0039] Preferably, the inner sides of the four gas pipelines 8 provided with the second nozzles 12 are all provided with second nozzles 13, and the side walls of the contraction flow channel 7 are provided with four through holes 14 matching the four second nozzles 13, and the spraying direction of the second nozzles 13 points to the through holes 14. Such a setting allows the gas sprayed from the second nozzles 13 to enter the contraction flow channel 7 through the through holes 14 on the contraction flow channel 7 for combustion assistance, thereby enhancing the ductility, stability and rigidity of the flame in the contraction flow channel 7, and facilitating the flame of the primary combustion to be stably sprayed out from the port of the contraction flow channel 7.

[0040] The present invention also provides a combustion method of a flame-segmented high-speed low-nitrogen burner, which comprises the following steps:

[0041] S1: Open the air inlet 15 to introduce air into the port of the central air pipeline 2;

[0042] S2: Open the central gas pipeline 3 to mix the gas and air at the port of the central air pipeline 2, and adjust the amount of air introduced into the air inlet 15 to form a mixed gas with an excess air coefficient greater than 1 at the port of the central air pipeline 2;

[0043] S3: Ignite the mixed gas by using the ignition gun 4, so that a stable flame is formed at the port of the central air pipeline 2;

[0044] S4: Open the air inlet channel 16 and the gas inlet channel 17, the gas sprayed from the first spray hole 6 is pre-mixed with the air in the air box 1, and then flows to the port of the central air pipeline 2, and mixes with the flame at the port of the central air pipeline 2, forming a primary combustion with excess air;

[0045] S5: The high-temperature flue gas and excess air generated by the primary combustion are ejected at high speed through the contraction flow channel 7 and mixed with the gas ejected from the second nozzle 12 on the gas pipeline 8 to form the first secondary combustion and eject a cylindrical stable flame;

[0046] S6: The cylindrical stable flame is mixed with the gas ejected from the first nozzle 11 on the gas pipeline 8 to form a second secondary combustion, and a larger columnar flame is formed, which wraps the stable flame formed by the first secondary combustion, thereby forming a secondary combustion with excess gas and ejecting a stable flame with uniform temperature.

[0047] Among them, the primary combustion zone is a fuel-lean zone, that is, the excess air coefficient is greater than the chemical equivalence ratio. At the same time, the excess air also reduces the combustion temperature, which comprehensively reduces the production of nitrogen oxides in the primary combustion zone; while the secondary combustion zone is a fuel-rich zone, the excess air coefficient deviates from the chemical equivalence ratio, and its combustion temperature is relatively high. However, due to the lack of oxygen combustion, the production of nitrogen oxides is suppressed, and the atmosphere in the fuel-rich area is a reducing atmosphere, which can reduce part of the nitrogen oxides produced by the primary combustion into nitrogen, further reducing the generation of nitrogen oxides during combustion.

[0048] In summary, the flame ejected by the burner of this scheme can be segmented and folded in radial and circumferential directions to form a petal-shaped flame, making the temperature distribution of the flame more uniform. At the same time, the folded flame surface can cause the flue gas to reflux, thereby deeply reducing the generation of nitrogen oxides. The axial gas staged combustion organization strategy is adopted, and the first-stage combustion adopts the premixed lean combustion method, and the second-stage combustion adopts the diffusion rich combustion method, which helps to reduce the generation of nitrogen oxides. At the same time, by controlling the gas flow rate and air flow rate, the burner can achieve a large-scale power adjustment of 1:10, and the lowest nitrogen oxide can reach 35mg / Nm 3 Below, for different types of steel billets, the heating method is flexible and helps to save energy and reduce carbon emissions.

Claims

1. A flame splitting high-speed low-nitrogen burner, characterized in that: The invention comprises an air box (1), wherein a flame generating device is arranged in the air box (1), a gas box (5) is arranged on the air box (1), the gas box (5) is connected to the air box (1) through a plurality of first spray holes (6), a contraction flow channel (7) is arranged at the port of the air box (1), a plurality of gas pipelines (8) are evenly arranged around the outside of the contraction flow channel (7), the gas pipelines (8) are connected to the gas box (5), a spray nozzle inclined toward the contraction flow channel (7) is arranged at the front end of the gas pipeline (8), a plurality of dividing bricks (9) are arranged in the gap on the outer wall of the contraction flow channel (7), a dividing plate (10) is arranged on the dividing brick (9), and a plurality of the dividing plates (10) are respectively arranged between two adjacent spray nozzles; The partition brick (9) is in the shape of an arc sheet, and the front end of the partition brick (9) protrudes from the port of the contraction flow channel (7), the partition plates (10) are respectively arranged on both sides of the outer arc surface of the partition brick (9), and the plurality of nozzles include a plurality of first nozzles (11) and a plurality of second nozzles (12) arranged alternately in the circumferential direction, the plurality of first nozzles (11) are respectively arranged between two partition plates (10) of the plurality of partition bricks (9), and the plurality of second nozzles (12) are respectively arranged between two partition plates (10) of two adjacent partition bricks (9); the inner side of the gas pipeline (8) provided with the second nozzles (12) is provided with a second spray hole (13), and the side wall of the contraction flow channel (7) is provided with a plurality of through holes (14) matched with the plurality of second spray holes (13), and the spraying direction of the second spray holes (13) points to the through holes (14); The gas pipeline (8) is wrapped with refractory material.

2. The flame-divided high-speed low-nitrogen burner according to claim 1 is characterized in that: The angle at which the first nozzle (11) is inclined toward the contraction flow channel (7) is smaller than the angle at which the second nozzle (12) is inclined toward the contraction flow channel (7).

3. The flame-divided high-speed low-nitrogen burner according to claim 1, characterized in that: The air box (1) is cylindrical, the gas box (5) is sleeved on the outer wall of the air box (1), and the plurality of first spray holes (6) are evenly distributed in the circumferential direction of the air box (1).

4. The flame-divided high-speed low-nitrogen burner according to claim 1, characterized in that: The flame generating device comprises a central air pipeline (2), wherein a central gas pipeline (3) and an ignition gun (4) are arranged in the central air pipeline (2), ports of the central gas pipeline (3) and the ignition gun (4) are arranged at the port of the central air pipeline (2), the port of the central air pipeline (2) is arranged at the port of the air box (1), and an air inlet (15) is arranged on the central air pipeline (2).

5. The flame-divided high-speed low-nitrogen burner according to claim 1, characterized in that: The air box (1) and the gas box (5) are respectively provided with an air inlet channel (16) and a gas inlet channel (17), and the plurality of first spray holes (6) are provided between the air inlet channel (16) and a port of the air box (1).

6. A combustion method using the flame-segmented high-speed low-nitrogen burner according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Open the air inlet (15) to introduce air into the port of the central air line (2); S2: opening the central gas pipeline (3) to allow the gas and air to mix at the port of the central air pipeline (2), and adjusting the amount of air introduced into the air inlet (15) to form a mixed gas with an excess air coefficient greater than 1 at the port of the central air pipeline (2); S3: Ignite the mixed gas by using the ignition gun (4) so ​​that a stable flame is formed at the port of the central air pipe (2); S4: opening the air inlet passage (16) and the gas inlet passage (17), so that the gas sprayed from the first spray hole (6) is pre-mixed with the air in the air box (1), and then flows to the port of the central air pipeline (2), and mixes with the flame at the port of the central air pipeline (2), thereby forming primary combustion with excess air; S5: The high-temperature flue gas and excess air generated by the primary combustion are ejected at high speed through the contraction flow channel (7) and mixed with the gas ejected from the second nozzle (12) on the gas pipeline (8), forming the first secondary combustion and ejecting a cylindrical stable flame; S6: The cylindrical stable flame is mixed with the gas ejected from the first nozzle (11) on the gas pipeline (8) to form a second secondary combustion, and a larger cylindrical flame is formed, which envelops the stable flame formed by the first secondary combustion, thereby forming a secondary combustion with excess gas and ejecting a stable flame with uniform temperature.

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