Low-nitrogen oxide gas burner with adjustable flame size

Abstract

This invention discloses a low-NOx gas burner, comprising: a combustion air passage and a gas passage, the gas passage surrounding the outer periphery of the combustion air passage, and an annular interlayer between the combustion air passage and the gas passage forming the nozzle of the gas burner; and a flame stabilizer assembly, comprising a flame stabilizer disc and a mounting tube, the flame stabilizer disc being fixed to the mounting tube, the mounting tube passing through the combustion air passage, the axis of the mounting tube being coaxial with the axis of the combustion air passage, and the air ejected from the combustion air passage and the gas ejected from the interlayer burning at the flame stabilizer disc. This burner can avoid coking or effectively extend the coking removal cycle; simultaneously, by utilizing its own structure, the burner reduces the local high temperature of the flame, effectively reducing the generation of nitrogen oxides.

Description

Technical Field

[0001] This application relates to the technical field of heating furnaces in the chemical industry, and in particular to a low-NOx gas burner with adjustable flame size. Background Technology

[0002] For a long time, the country has been strengthening its environmental protection efforts, and emission standards for pollutants in flue gas have become increasingly stringent. NOx emissions have caused huge economic losses, leading to the rapid development of low-NOx burners. Low-NOx burners are burners that can effectively reduce nitrogen oxides through their own structure and have attracted much attention in the market. How to further reduce nitrogen oxides produced by existing low-NOx burners and avoid coking in them are problems that need to be solved. Summary of the Invention

[0003] The purpose of this invention is to provide a flame-size adjustable low-NOx gas burner that can avoid coking or effectively extend the decoking cycle; at the same time, the burner utilizes its own structure to reduce the local high temperature of the flame, which can effectively reduce the generation of nitrogen oxides.

[0004] In a first aspect, a gas burner is provided, comprising:

[0005] A combustion air passage and a gas passage, wherein the gas passage surrounds the outer periphery of the combustion air passage, and the annular interlayer of the combustion air passage and the gas passage constitutes the nozzle of the gas burner;

[0006] A flame stabilizer assembly includes a flame stabilizer and a mounting tube. The flame stabilizer is fixed on the mounting tube, which passes through the combustion air passage. The axis of the mounting tube is coaxial with the axis of the combustion air passage. The air ejected from the combustion air passage and the fuel gas ejected from the interlayer are burned at the flame stabilizer.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, the nozzle is provided with a plurality of nozzle baffles, which are symmetrically arranged or circumferentially uniformly arranged.

[0008] In conjunction with the first aspect, in some implementations of the first aspect, the arrangement of the plurality of nozzle baffles satisfies:

[0009] f is the nozzle area after multiple nozzle baffles block the flow, G is the gas flow rate, r is the gas density, P1 is the gas pressure, and P2 is the nozzle outlet pressure.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, the flame stabilizer is in the shape of a conical disc, the conical end of the flame stabilizer is connected to the mounting tube (i.e. the open end of the flame stabilizer is positioned away from the nozzle), and the cone angle W of the flame stabilizer is 90° to 180°.

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the gas burner further includes:

[0012] The air box, the combustion air passage and the gas passage are fixedly installed inside the air box;

[0013] A connecting flange is fixed to the air box, and the connecting flange includes a center hole;

[0014] A positioning sleeve is fixed in the central hole. The side wall of the positioning sleeve is provided with a sleeve through hole. The mounting tube can move along the axis inside the positioning sleeve. The mounting tube is provided with a plurality of positioning holes arranged along the axis. One of the plurality of positioning holes is aligned with the sleeve through hole and locked by a lock nut.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the height h of the flame stabilizer and the nozzle is adjustable within the range of 30mm to 200mm.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, the gas passage includes a gas nozzle portion and a gas collection portion, the gas nozzle portion being located at the end of the gas passage closer to the nozzle, the gas collection portion being located at the end of the gas passage farther from the nozzle, and the inner diameter of the gas nozzle portion being smaller than the inner diameter of the gas collection portion.

[0017] In conjunction with the first aspect, in some implementations of the first aspect, the air flow rate within the combustion air channel is 6 to 12 m / s.

[0018] In conjunction with the first aspect, in some implementations of the first aspect, the cross-sectional area of ​​the interlayer is greater than or equal to 80% of the cross-sectional area of ​​the gas inlet pipe.

[0019] In conjunction with the first aspect, in some implementations of the first aspect, the projection area of ​​the nozzle in the axial direction is located within the projection area of ​​the flame stabilizer in the axial direction.

[0020] Compared with the prior art, the solution provided in this application has at least the following beneficial technical effects:

[0021] For heat media prone to coking, properly controlling the flame size, ensuring the heating requirements in the furnace, and maintaining the temperature distribution within the furnace to prevent pipe licking and the generation of localized high temperatures can avoid coking or extend the pipe cleaning cycle, reduce maintenance costs, and greatly improve production efficiency.

[0022] This burner features an adjustable flame stabilizer. By adjusting the distance between the flame stabilizer and the gas nozzle, the combustion of fuel is controlled, thereby controlling the flame size and creating a uniformly heated flame. This prevents the formation of high-temperature zones, meeting the heating requirements of the furnace and effectively avoiding coking or extending the decoking cycle of the pipeline. The burner also isolates air and fuel gas, slowing down fuel-air mixing. Simultaneously, it entrains inert flue gas in the furnace, reducing localized high temperatures during flame combustion and decreasing the formation of nitrogen oxides.

[0023] This invention relates to an adjustable-flame-size low-NOx gas burner, primarily used in heating furnaces in the chemical industry. This burner can burn blast furnace gas, natural gas, coke oven gas, and mixtures of these gases, exhibiting strong fuel adaptability and stable, reliable operation. The burner allows for flame size adjustment based on furnace temperature requirements, regulating heat distribution within the furnace. It ensures uniform flame temperature distribution, prevents flame licking, and effectively reduces localized high temperatures, making it suitable for heating furnaces where the heated medium is prone to coking. Furthermore, the fuel's structure enables it to entrain flue gas within the furnace, reducing nitrogen oxide production.

[0024] The specially designed adjustable flame stabilizer effectively regulates the flame size and controls the furnace temperature, preventing coking of the furnace tubes or extending the decoking cycle. This structure has low manufacturing costs, reducing maintenance costs and significantly improving the efficiency of the heating furnace. The burner's structure effectively isolates fuel and air, slowing the combustion rate and creating a low-NOx combustion effect. Simultaneously, it creates a localized negative pressure zone during combustion, drawing in inert flue gas from the furnace to participate in combustion, achieving low-oxygen combustion and effectively reducing the formation of nitrogen oxides. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a low-NOx gas burner with adjustable flame size.

[0026] Figure 2 This is a schematic diagram of the gas passage and nozzle.

[0027] Figure 3 This is a schematic diagram of a height-adjustable flame stabilizer assembly.

[0028] Figure 4 This is a schematic diagram showing the shape of the flame at different heights h.

[0029] Explanation of reference numerals in the attached drawings: 1. Bellows, 2. Adjustable damper, 3. Flame stabilizer assembly, 4. Ignition gun, 5. Gas inlet, 6. Gas passage, 7. Observation hole, 8. Burner brick, 9. Insulation cotton, 10. Combustion air passage, 12. Lower collector plate, 13. Upper collector plate, 14. Nozzle baffle, 15. Collector steel cylinder, 16. Mounting pipe, 17. Locking nut, 18. Positioning sleeve, 19. Flame stabilizer, 20. Connecting flange. Detailed Implementation

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 This is a schematic structural diagram of a flame-size adjustable low-NOx gas burner provided in an embodiment of this application.

[0032] The burner may include a bellows 1. The bellows 1 contains a combustion air passage 10. The combustion air passage 10 may be, for example, a circular channel formed by a steel plate. The lower end of the combustion air passage 10 may communicate with an air inlet, allowing combustion air to enter the combustion air passage 10 through the air inlet. An adjustable damper 2 may be installed at the air inlet. The adjustable damper 2 is used to control the airflow entering the combustion air passage 10. The upper end of the combustion air passage 10 may form the inner cylinder of the bellows nozzle. The nozzle faces the flame stabilizer 19, allowing the combustion air in the combustion air passage 10 to exit the nozzle and participate in combustion at the flame stabilizer 19. The bottom of the bellows 1 is used to constrain the axis of the flame stabilizer assembly 3 to be coaxial with the axis of the combustion air passage 10.

[0033] In some embodiments provided in this application, the inner cylinder of the nozzle is an air flow channel, and the cross-sectional area of ​​the flow channel can be determined according to the air flow velocity, which is usually between 6 and 12 m / s.

[0034] The bellows 1 may also include a gas passage 6. The gas passage 6 surrounds the outer periphery of the combustion air passage 10. The lower end of the gas passage 6 can communicate with the gas port 5, through which gas can enter the gas passage 6. The upper end of the gas passage 6 can form the outer cylinder of the bellows nozzle, through which gas can be ejected through the interlayer between the gas passage 6 and the combustion air passage 10. After exiting the nozzle, the gas in the gas passage 6 can participate in combustion at the flame stabilizer 19. The upper sidewall of the gas passage 6 can be welded and fixed to the upper plate of the bellows 1, thereby indirectly constraining the positional relationship between the combustion air passage 10, the gas passage 6, and the flame stabilizer assembly 3 through the bellows 1.

[0035] In some embodiments provided in this application, the interlayer formed by the outer nozzle cylinder and the inner nozzle cylinder is used for the flow of gas. The cross-sectional area of ​​this interlayer can be determined according to the diameter of the inner nozzle cylinder, and generally the cross-sectional area of ​​this interlayer can be greater than or equal to 80% of the cross-sectional area of ​​the gas inlet pipe.

[0036] exist Figure 1 In the illustrated embodiment, the gas passage 6 has a gas collecting portion and a gas nozzle portion. The gas collecting portion is located at the end of the gas passage 6 furthest from the flame stabilizer 19, i.e., at the end of the gas passage 6 closest to the gas inlet 5. The gas nozzle portion is located at the end of the gas passage 6 closest to the flame stabilizer 19, i.e., at the end of the gas passage 6 furthest from the gas inlet 5. In the gas collecting portion, the distance between the gas passage 6 and the combustion air passage 10 is distance 1; in the gas nozzle portion, the distance between the gas passage 6 and the combustion air passage 10 is distance 2; distance 1 can be greater than distance 2. Figure 2 As shown, the gas passage 6 is equipped with a lower collector plate 12 and an upper collector plate 13, thereby allowing gas to pass through the side wall of the combustion air passage 10 and the side wall of the gas passage 6 (i.e., Figure 2 The middle collector steel cylinder 15), the lower collector plate 12 and the upper collector plate 13 form the gas collection part to form a gas passage with a relatively larger spacing on the gas passage 6.

[0037] In some embodiments provided in this application, such as Figure 2 As shown, multiple nozzle baffles 14 can be installed in the interlayer between the gas passage 6 and the combustion air passage 10. The nozzle baffles 14 can be arranged perpendicularly to the axis of the flame stabilizer assembly 3. In one possible scenario, the nozzle baffles 14 can be welded to the inner and outer cylinders of the nozzle. Multiple nozzle baffles 14 can be evenly distributed circumferentially around the axis of the flame stabilizer assembly 3.

[0038] In some embodiments, the nozzle baffle 14 is used to divide the gas interlayer, which helps to ensure complete combustion of the gas. The number of nozzle baffles 14 is generally greater than six. If the number of nozzle baffles 14 is too small, it will not effectively divide the combustion zone. The area size of the nozzle is determined by both the gas pressure and the burner load, thus allowing for the design of different baffle sizes. The baffle size can be adjusted arbitrarily according to the design to meet the load requirements. Generally, low-pressure gas can be calculated using the following formula: f is the nozzle area, G is the gas flow rate, r is the gas density, P1 is the gas pressure, and P2 is the nozzle outlet pressure.

[0039] In some embodiments provided in this application, such as Figure 3As shown, the flame stabilizing plate 19 is a large-angle conical plate. The cone angle W of the conical plate is used to control the distribution of air after passing through the flame stabilizing plate 19. The cone angle W ranges from 90° to 180°. When the angle W is small, the air dispersion after passing through the flame stabilizing plate 19 is small, the flame diameter is relatively small, the flame is concentrated, and the flame height is long. This is often used in process heating furnaces with small furnace volume and the heat exchange surface is mainly arranged in the upper part of the furnace. When the angle W is large, the air dispersion after passing through the flame stabilizing plate 19 is large, the flame diameter is large, and the corresponding height is small. This is often used in heating furnaces with more heat exchange in the lower part of the furnace. The flame height is small, and the high-temperature flue gas in the upper part of the furnace is mainly high-temperature flue gas, which is heated evenly and is less likely to cause flame licking and local high temperature phenomena. In actual use, the angle of the flame stabilizing plate 19 can be changed according to the heat exchange requirements of the furnace.

[0040] In some embodiments provided in this application, such as Figure 1 and Figure 3 As shown, the flame stabilizer assembly 3 may include an installation tube 16, a locking nut 17, a positioning sleeve 18, a flame stabilizer 19, and a connecting flange 20. One end of the installation tube 16 is fixed to the flame stabilizer 19, and the other end of the installation tube 16 passes through the central hole of the connecting flange 20 and can move along the axis within the central hole of the connecting flange 20. The connecting flange 20 is fixedly connected to the bellows 1. Multiple positioning holes are provided on the side wall of the installation tube 16, arranged along the axis of the flame stabilizer assembly 3. The positioning sleeve 18 is fixed within the central hole of the connecting flange 20, and its side wall has a sleeve through-hole. By aligning one of the multiple positioning holes with the sleeve through-hole and locking the two holes with the locking nut 17, the installation tube 16 is locked and fixed on the connecting flange 20. By adjusting the positioning hole aligned with the sleeve through-hole, the position of the installation tube 16 relative to the bellows 1 can be changed, the height of the flame stabilizer 19 relative to the nozzle can be changed, thereby adjusting the fuel and air mixing time and controlling the flame size.

[0041] like Figure 4 The diagram shows the flame profile at different heights h (the height between the flame stabilizing plate 19 and the nozzle). The value of h relates to the flame diameter and nitrogen oxide emissions. When the height is h1 (relatively low), the flame is blocked by the flame stabilizing plate 19 and moves to both sides along the plate, resulting in a short flame with a large diameter. When the height is h2 (relatively high, h2>h1), the blocking effect of the flame stabilizing plate 19 decreases, resulting in a long flame with a small diameter. By adjusting different heights h, the required furnace temperature can be met. In some embodiments, h ranges from 30mm to 200mm.

[0042] When h is large, the flame diameter is small and the flame height is long. This results in stable combustion and a concentrated high-temperature zone, leading to relatively high nitrogen oxide (NOx) formation. This type of furnace is often used in process furnaces where NOx requirements are not high. When h is small, the flame diameter is large and the flame height is short. This results in delayed contact between air and fuel gas, facilitating low-NOx combustion. In practical applications, h can be adjusted according to the required flame size and NOx requirements. If h is too small, it will affect airflow, preventing the fuel from receiving sufficient air and causing unstable combustion. Therefore, it is advisable to keep h within a certain range for practical use.

[0043] In the burner, fuel gas and air enter separately. The fuel gas enters the collector through a gas pipeline, where an inner and outer nozzle cylinder form a rising gas channel. It is then sprayed out after being divided by a baffle plate at the nozzle outlet. Combustion air enters from the air box 1, flows upwards along the inner cylinder of the air box 1 into the burner, and passes through the flame stabilizer assembly 3. The combustion air is evenly distributed around the flame stabilizer 19 to participate in combustion. This flame stabilizer assembly 3 is designed with a height-adjustable component. By adjusting the locking nut 17, the distance between the flame stabilizer 19 and the fuel nozzle can be moved up and down, adjusting the fuel-air mixing time and thus the flame size. This prevents flame licking and localized high temperatures, ensuring the flame size more rationally meets the furnace temperature distribution. Because the combustion air is evenly distributed, the fuel flame temperature is uniform, reducing the likelihood of coking of the medium in the heated pipes. Because air and fuel are introduced separately, the combustion air and fuel move along the flame stabilizer 19 and away from the burner centerline for combustion, slowing down the fuel combustion rate and significantly reducing the local high temperature of the flame. This is unfavorable for the generation of nitrogen oxides and reduces the probability of flame licking and furnace tube coking. In addition, the projection area of ​​the nozzle in the axial direction is located within the projection area of ​​the flame stabilizer 19 in the axial direction, which helps to form a local negative pressure area directly above the flame stabilizer 19. This entrains inert flue gas in the furnace for low-oxygen combustion, and the reaction deviates from the stoichiometric ratio, which can effectively reduce the local high temperature of the flame, thereby achieving the purpose of reducing nitrogen oxides.

[0044] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A gas burner, characterized in that, include: Combustion air passage (10) and gas passage (6), the gas passage (6) surrounding the outer periphery of the combustion air passage (10), the annular sandwich of the combustion air passage (10) and the gas passage (6) constitutes the nozzle of the gas burner; Flame stabilizer assembly (3), the flame stabilizer assembly (3) includes a flame stabilizer (19) and an mounting tube (16), the flame stabilizer (19) is fixed on the mounting tube (16), the mounting tube (16) passes through the combustion air passage (10), the axis of the mounting tube (16) and the axis of the combustion air passage (10) are coaxial, the air ejected from the combustion air passage (10) and the gas ejected from the interlayer are burned at the flame stabilizer (19); The flame stabilizer (19) is in the shape of a conical disc, and the conical end of the flame stabilizer (19) is connected to the mounting tube (16). The cone angle W of the flame stabilizer (19) is 90°~180°. The height h of the flame stabilizer (19) and the nozzle is adjustable within the range of 30mm to 200mm; The gas burner also includes: The air box (1), the combustion air passage (10) and the gas passage (6) are fixedly installed inside the air box (1); A connecting flange (20) is fixed to the air box (1), and the connecting flange (20) includes a center hole; A positioning sleeve (18) is fixed in the central hole. The side wall of the positioning sleeve (18) is provided with a sleeve through hole. The mounting tube (16) can move along the axis inside the positioning sleeve (18). The mounting tube (16) is provided with multiple positioning holes arranged along the axis. One of the multiple positioning holes is aligned with the sleeve through hole and locked by a locking nut (17).

2. The gas burner according to claim 1, characterized in that, The nozzle is provided with multiple nozzle baffles (14), which are symmetrically arranged or uniformly arranged circumferentially.

3. The gas burner according to claim 1, characterized in that, The gas passage (6) includes a gas nozzle portion and a gas collection portion. The gas nozzle portion is located at the end of the gas passage (6) closer to the nozzle, and the gas collection portion is located at the end of the gas passage (6) farther from the nozzle. The inner diameter of the gas nozzle portion is smaller than the inner diameter of the gas collection portion.

4. The gas burner according to claim 1, characterized in that, The air flow rate in the combustion air channel (10) is 6 to 12 m / s.

5. The gas burner according to claim 1, characterized in that, The cross-sectional area of ​​the annular interlayer is greater than or equal to 80% of the cross-sectional area of ​​the gas inlet pipe.

6. The gas burner according to claim 1, characterized in that, The projection area of ​​the nozzle in the axial direction is located within the projection area of ​​the flame stabilizer (19) in the axial direction.

Images