A fully premixed low-nitrogen burner with adjustable end cover

Abstract

The present invention discloses a fully premixed low-nitrogen burner with an adjustable end cover, which belongs to the technical field of burners. The burner comprises an air channel and a coaxially arranged gas ring cavity thereof, wherein the air channel is connected to a contraction tube and a straight flame tube in sequence, wherein the contraction tube is in the shape of a conical barrel contraction, is connected to the air channel upstream, and is connected to the straight flame tube downstream, and is connected to a flame end cover downstream of the straight flame tube, wherein the contraction tube, the straight flame tube and the flame end cover are all coaxially arranged with the air channel, and the air channel is connected to a main gas pipeline at its lower portion, and a plurality of evenly distributed gas branch pipes are arranged in the air channel, wherein the gas branch pipes have closed centripetal ends and are connected to the gas ring cavity at eccentric ends, and a plurality of gas outlet holes are distributed on the pipe wall of the gas branch pipes; the problem that air and gas of a diffusion burner are difficult to mix very evenly, local high temperature is prone to occur, and temperature distribution in the furnace is uneven, which is prone to cause increased nitrogen oxide emissions, is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of burners, and in particular relates to a fully premixed low-nitrogen burner with an adjustable end cover. Background Art

[0002] The burner is an important part of the heating furnace. It can be divided into gas burners, oil burners, etc. according to the type of fuel. Gas burners are divided into premixed burners and diffusion burners according to whether the gas and air are premixed. The heating furnace produces a large amount of flue gas during operation, which contains atmospheric pollutants such as nitrogen oxides and carbon dioxide, which have a bad impact and harm on the human body and the environment. The restrictions on the emission of such pollutants at home and abroad are becoming more and more stringent; the premixed burner is a burner designed according to the complete premixed combustion method. Before combustion, the gas and the supply air are premixed and then sprayed out through the burner's jet pipe (or metal fiber combustion head) for combustion. The premixed burner is premixed evenly, so it can achieve complete combustion at the best excess air coefficient. In addition, the temperature is relatively uniform during combustion, and it is not easy to have local high temperature, which effectively reduces the emission of nitrogen oxides. However, the use of metal fiber surface combustion is prone to blockage, high oxygen content, and difficult maintenance.

[0003] In reference patent CN 108730975 A, a premixed combustion structure using non-metallic fibers is used, which effectively avoids the disadvantages of the metal fiber structure. However, there are also problems such as poor mixing, easy flashback, and the inability to adjust the flame structure due to nozzle fixation. Summary of the invention

[0004] The purpose of the present invention is to provide an adjustable end cover fully premixed low-nitrogen burner, which applies premixing technology, flue gas internal circulation technology, etc. to forced draft burner technology, aiming to solve the problem of high nitrogen oxide emissions from commonly used boiler gas burners.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an adjustable end cover full premixed low-nitrogen burner, comprising an air channel and a coaxially arranged gas ring cavity, wherein the air channel is sequentially connected to a contraction tube and a straight flame tube, wherein the contraction tube is in a conical barrel contraction shape, connected to the air channel upstream, and connected to the straight flame tube downstream, wherein the straight flame tube is connected to a flame end cover downstream, wherein the contraction tube, the straight flame tube, and the flame end cover are all coaxially arranged with the air channel, and the air channel is connected to a main gas pipeline below;

[0006] The air passage is provided with a plurality of evenly distributed gas branch pipes, the centripetal end of the gas branch pipes is closed, the eccentric end is connected to the gas ring cavity, a plurality of gas outlet holes are distributed on the pipe wall of the gas branch pipes, valves are provided on the outer surfaces of the plurality of gas outlet holes, the gas outlet holes on each gas branch pipe are distributed on the side wall of the gas branch pipe along the length direction of the gas branch pipe, and the gas outlet direction of the gas outlet holes is perpendicular to the central axis direction of the air passage;

[0007] The flame end cover is a solid frustum, comprising an end cover side wall, the inner wall of the flame end cover is connected to the end cover pull rod, a number of end cover support rods are evenly installed on the end cover side wall, a number of support rod mounting seats are evenly arranged on the inner wall of the downstream end of the straight flame tube, the other end of the end cover support rod is sleeved in the support rod mounting seat, the number of the end cover support rod and the support rod mounting seat is the same, a number of peripheral oblique injection holes and inner circle axial flow injection holes are evenly opened on the flame end cover, the opening direction of the peripheral oblique injection hole and the central axis direction of the air channel are at a certain angle, inclined outward, the diameter of the inner circle axial flow injection hole at the center position of the flame end cover is smaller than that of the peripheral oblique injection hole, and its opening is parallel to the central axis direction of the air channel, and the pull rod and the straight flame tube are coaxially arranged;

[0008] A swirl blade sleeve and a plurality of swirl blades are arranged in the upstream end of the straight flame tube, the swirl blades are evenly mounted on the swirl blade sleeve, the swirl blade sleeve is sleeved outside the end cover tie rod, the inner diameter of the swirl blade sleeve is slightly larger than the outer diameter of the end cover tie rod, so that the end cover tie rod can move in the axial direction;

[0009] One section of the end cover pull rod is connected to the flame end cover, and the other end is located in the air channel, on which a number of evenly distributed gear teeth are arranged. A gear is arranged in the air channel, and the gear is provided with a gear shaft. The gear and the gear teeth can cooperate and link. The air channel is provided with an inner wall gear shaft sleeve and an outer wall gear shaft mounting seat. The outer wall gear shaft mounting seat) is a boss with a wall thickness greater than that of the air channel. The outer wall gear shaft mounting seat) is provided with a gear shaft hole and a dial is provided on the outer wall surface. One end of the gear shaft is sleeved in the inner wall gear shaft sleeve, and the other end passes through the gear shaft hole and extends out a section, and can rotate freely. A sealing ring is provided at the connection between the gear shaft hole and the gear shaft to prevent air leakage. One end of the gear shaft extending out of the wheel shaft mounting seat) is provided with a rocker and a pointer, and the pointer rotates with the rotation of the gear shaft and points to the range of the dial. The axial direction of the gear shaft is perpendicular to the central axial direction of the air channel.

[0010] As a technical optimization solution of the present invention, the number of swirl blades is 4 to 15.

[0011] As a technical optimization solution of the present invention, the swirl angle of the swirl blade is 20° to 60°.

[0012] As a technical optimization solution of the present invention, the angle between the side wall of the end cover and the central axis of the air channel is 30° to 90°.

[0013] As a technical optimization solution of the present invention, the angle between the peripheral oblique injection hole and the central axis direction of the air channel is 10° to 60°.

[0014] As a technical optimization solution of the present invention, the number of the peripheral oblique injection holes is 4 to 20.

[0015] As a technical optimization solution of the present invention, the number of axial flow injection holes in the inner ring is 4 to 20.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The combination of premixed combustion and flue gas internal circulation technology has a better nitrogen reduction effect;

[0018] (2) It solves the problem that the air and gas in the diffusion burner are difficult to mix very evenly, which easily leads to local high temperature and uneven temperature distribution in the furnace, which easily causes increased nitrogen oxide emissions.

[0019] (3) The clogging problem of the mixer and combustion head of the metal fiber surface full premixed burner has been solved, making daily maintenance simpler and reducing maintenance costs;

[0020] (4) An adjustment mechanism is added to the end cover of the burner head, which can adjust the shape of the flame and make the burner more adaptable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 for Figure 1 A front view of

[0023] Figure 3 for Figure 1 Schematic diagram of the three-dimensional structure;

[0024] Figure 4 It is a schematic diagram of the side structure of the present invention.

[0025] In the figure: 1-air channel, 2-main gas pipeline, 3-gas ring cavity, 4-contraction tube, 5-straight flame tube, 6-flame end cover, 7-gas branch pipe, 8-gas outlet, 9-outer oblique injection hole, 10-inner axial injection hole, 11-pull rod, 12-gear tooth, 13-swirl blade sleeve, 14-swirl blade, 15-gear, 16-end cover support rod, 17-support rod mounting seat, 18-pointer, 19-dial, 20-valve, 21-inner wall gear shaft sleeve, 22-gear shaft, 23-sealing ring, 24-gear shaft hole, 25-end cover side wall. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments.

[0027] The following examples are used to illustrate the present invention, but they cannot be used to limit the scope of protection of the present invention. The conditions in the examples can be further adjusted according to specific conditions. Simple improvements to the method of the present invention under the premise of the concept of the present invention belong to the scope of protection claimed in the present invention.

[0028] Embodiment 1

[0029] Combination Figure 1-4As shown, the present invention provides an adjustable end cover full premixed low nitrogen burner, including an air channel 1 and a coaxially arranged gas ring cavity 3 thereof, the air channel 1 is connected in sequence to a contraction tube 4 and a straight flame tube 5. The contraction tube 4 is in a conical barrel contraction shape, connected to the air channel 1 upstream, and connected to the straight flame tube 5 downstream. The straight flame tube 5 is connected to the flame end cover 6 downstream. The contraction tube 4, the straight flame tube 5, and the flame end cover 6 are all coaxially arranged with the air channel 1, and are connected to the main gas pipeline 2 below the air channel 1. A plurality of evenly distributed gas branch pipes 7 are arranged in the air channel 1, and the gas branch pipe 7 is closed at the centripetal end and connected to the gas ring cavity 3 at the eccentric end. A plurality of gas outlet holes 8 are distributed on the pipe wall of the gas branch pipe 7, and valves 20 are arranged on the outer surfaces of the plurality of gas outlet holes 8. Each gas branch pipe 7 has a valve 20 on its outer surface. The gas outlet holes 8 are distributed on the side wall of the gas branch pipe 7 along the length direction of the gas branch pipe 7, and the outlet direction of the gas outlet holes 8 is perpendicular to the central axis direction of the air channel 1. The flame end cover 6 is a solid frustum, including an end cover side wall surface 25. The inner wall surface of the flame end cover 6 is connected to the end cover pull rod 11, and a number of end cover support rods 16 are evenly installed on the end cover side wall surface 25. The end cover side wall surface 25 is an inclined surface, which forms a certain angle with the central axis direction of the air channel 1 and is inclined outward. A number of support rod mounting seats 26 are evenly arranged on the inner wall of the downstream end of the straight flame tube 5, and the other end of the end cover support rod 16 is sleeved in the support rod mounting seat 26, and the number of the end cover support rods 16 and the support rod mounting seat 26 is the same. A number of peripheral oblique injection holes 9 and inner ring axial flow injection holes are evenly opened on the flame end cover 6 The opening direction of the peripheral oblique injection hole 9 is at a certain angle to the central axis direction of the air channel 1. The diameter of the outwardly inclined inner ring axial flow injection hole 10 at the center position of the flame end cover 6 is smaller than that of the peripheral oblique injection hole 9. The opening is parallel to the central axis direction of the air channel 1. The tie rod 11 and the straight flame tube 5 are coaxially arranged. A swirl blade sleeve 13 and a plurality of swirl blades 14 are arranged in the upstream end of the straight flame tube 5. The swirl blades 14 are evenly installed on the swirl blade sleeve 13. The swirl blade sleeve 13 is sleeved outside the end cover tie rod 11. The inner diameter of the swirl blade sleeve 13 is slightly larger than the outer diameter of the end cover tie rod 11, so that the end cover tie rod 11 can move in the axial direction. One end of the end cover tie rod 11 is connected to the flame end cover 6, and the other end is located in the air channel 1. A plurality of swirl blades 14 are arranged on the upstream end of the straight flame tube 5. The gear 15 is arranged in the air passage 1 with evenly distributed gear teeth 12, and the gear 15 is provided with a gear shaft 22. The gear 15 and the gear teeth 12 can cooperate with the linkage air passage 1 to set the inner wall gear shaft sleeve 21 and the outer wall gear shaft mounting seat 17. The outer wall gear shaft mounting seat 17) is a boss with a wall thickness greater than that of the air passage 1, and the outer wall gear shaft mounting seat 17) is provided with a gear shaft hole 24 and a dial 19 is arranged on the outer wall surface. One end of the gear shaft 22 is sleeved in the inner wall gear shaft sleeve 21, and the other end passes through the gear shaft hole 24 and extends out for a section, and can rotate freely. A sealing ring is arranged at the connection between the gear shaft hole 24 and the gear shaft 22 to prevent air leakage. The gear shaft 22 extends out of the wheel shaft mounting seat 17). One end is provided with a rocker 17 and a pointer 18. The pointer 18 rotates with the rotation of the gear shaft 22.And it points to the range of the scale plate 19. The axial direction of the gear shaft 22 is perpendicular to the central axial direction of the air channel 1. The air intake pipe 1 is used as a channel for air to flow into the burner, and the main gas pipeline 2 is used as a channel for gas to enter the burner. The gas flows into the gas ring cavity 3 from the main gas pipeline 2, and is ejected from multiple gas outlets 8 distributed on both sides of a number of gas branch pipes 7 evenly distributed on the inner side of the gas ring cavity 3, and is initially mixed with the air from the air intake pipe 1. The mixed gas enters the contraction tube 4 downstream along the air intake pipe 1 for compression, acceleration and further mixing, and then flows through the swirl blades 14 to form a swirl, which strengthens the mixing of gas and air and promotes uniform mixing. After that, the mixed gas flows into the straight flame tube 5 for further development until it is divided into multiple mixed gases and flows out from the flame end cover 6. A part of the mixed gas is ejected from the inner ring axial flow injection hole 10 and burns in the central area of ​​the burner to form a primary flame area. This part of the flame is located in the center of the combustion space. Since the flame end cover 6 forms a blunt body to block the flow of the mixed gas, the mixed gas in the downstream The central area forms a reflux flame stabilization area, so the primary flame area burns stably, forming a mechanism for stable flame. A part of the mixed gas is ejected obliquely outward from the outer oblique injection hole 9 to form a secondary flame area. This part of the flame is separated from the primary flame area to form a mixed gas classification, avoiding the generation of high-temperature areas. The remaining mixed gas is ejected obliquely outward from the channel between the end cover side wall surface 25 and the end surface of the straight flame tube 5, forming a tertiary flame area. This area is located at the periphery of the combustion field and develops downstream to form a jet entrainment, which continuously entrains and refluxes the smoke, which can further reduce the flame combustion temperature to reduce the generation of nitrogen oxides. The secondary flame area is located between the primary flame area and the tertiary flame, and plays a role in transferring heat and stabilizing the flame, so that the entire flame burns safely, stably and continuously, forming a stable combustion atmosphere. Due to complete premixing, premixed combustion is formed, which can achieve complete combustion at the optimal excess air coefficient, so that the emission value of nitrogen oxides is very low. Each combustion area produces a mixing effect and a shearing effect under the swirl effect, and carries out intense material and heat transfer, forming a stable and efficient combustion area together. ,

[0030] When in use, an end cover adjustment structure is provided at the burner head, which consists of a flame end cover 6, an end cover pull rod 11, a gear 12 at one end of the end cover pull rod 11, a gear 15, a gear shaft 22, an inner wall gear shaft sleeve 21 and an outer wall gear shaft mounting seat 17, a rocker 17, a pointer 18 and a dial 19. By rotating the rocker 17, the gear shaft 22 is driven to rotate, and the gear 15 also rotates accordingly. The gear 12 meshing with the gear 15 drives the end cover pull rod 11 to move axially. At this time, the flame end cover 6 fixed at the other end of the end cover pull rod 11 also moves in the axial direction. The channel distance between the end cover side wall surface 25 and the end surface of the straight flame tube 5 can be adjusted, thereby adjusting the shape of the flame ejected from the channel. Since the flame end cover is sleeved on the support rod mounting seat 26 on the straight flame tube 5 through a plurality of end cover support rods 16, it can move axially, but the movement in the radial direction is limited, and The end cover pull rod 11 is sleeved in the swirl blade sleeve 13. The inner diameter of the swirl blade sleeve 13 is slightly larger than the outer diameter of the end cover pull rod 11, which also limits the end cover pull rod 11 to move only in the axial direction but not in the radial direction. This ensures that during the adjustment process, the end cover will not be tilted, resulting in uneven channel distance between the end cover side wall 25 and the end face of the straight flame tube 5, and also avoids the failure of the engagement of the gear teeth 12 and the gear 15. The gear shaft 22 is installed on the inner wall gear shaft sleeve 21 and the outer wall gear shaft mounting seat 17 set in the air channel 1, wherein the gear shaft hole 24 of the outer wall gear shaft mounting seat 17 and the gear shaft 22 are connected with a sealing ring to prevent air leakage; the pointer 18 installed on the gear shaft 12 rotates with the rotation of the gear shaft 22 and points to the range of the dial 19, and the dial 19 is engraved with the value of the channel distance between the end cover side wall 25 and the end face of the straight flame tube 5, which is convenient for observation and adjustment.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An adjustable end cover full premixed low nitrogen burner, comprising an air channel (1) and a coaxially arranged gas ring cavity (3), characterized in that: The air channel (1) is connected to a contraction tube (4) and a straight flame tube (5) in sequence. The contraction tube (4) is in the shape of a conical barrel contraction, connected to the air channel (1) at the upstream and connected to the straight flame tube (5) at the downstream. The straight flame tube (5) is connected to a flame end cover (6) at the downstream. The contraction tube (4), the straight flame tube (5) and the flame end cover (6) are all coaxially arranged with the air channel (1). The lower part of the air channel (1) is connected to the main gas pipeline (2). A plurality of evenly distributed gas branch pipes (7) are arranged in the air channel (1). The gas branch pipes (7) are closed at the centripetal end and connected to the gas annular cavity (3) at the eccentric end. A plurality of gas outlet holes (8) are distributed on the pipe wall of the gas branch pipe (7). The gas outlet holes (8) on each gas branch pipe (7) are distributed on the side wall of the gas branch pipe (7) along the length direction of the gas branch pipe (7). The gas outlet direction of the gas outlet hole (8) is perpendicular to the central axis direction of the air channel (1). The flame end cover (6) is a solid truncated cone body, comprising an end cover side wall surface (25). The inner wall surface of the flame end cover (6) is connected to the end cover pull rod (11). A plurality of end cover support rods (16) are evenly installed on the end cover side wall surface (25). The end cover side wall surface (25) is an inclined surface, which forms a certain angle with the central axis direction of the air channel (1) and is inclined outward. A plurality of support rod mounting seats (26) are evenly arranged on the inner wall of the downstream end of the straight flame tube (5). The other end of the end cover support rod (16) is sleeved in the support rod mounting seat (26). 16) and the number of support rod mounting seats (26) are the same, and a plurality of peripheral oblique injection holes (9) and inner ring axial flow injection holes (10) are evenly opened on the flame end cover (6). The opening direction of the peripheral oblique injection holes (9) is at a certain angle to the central axis direction of the air channel (1) and is inclined outward. The diameter of the inner ring axial flow injection holes (10) at the center position of the flame end cover (6) is smaller than that of the peripheral oblique injection holes (9), and the opening thereof is parallel to the central axis direction of the air channel (1). The end cover pull rod (11) is coaxially arranged with the straight flame tube (5); A swirl blade sleeve (13) and a plurality of swirl blades (14) are arranged in the upstream end of the straight flame tube (5), the swirl blades (14) are evenly mounted on the swirl blade sleeve (13), the swirl blade sleeve (13) is sleeved outside the end cover tie rod (11), the inner diameter of the swirl blade sleeve (13) is slightly larger than the outer diameter of the end cover tie rod (11), so that the end cover tie rod (11) can move in the axial direction; One end of the end cover tie rod (11) is connected to the flame end cover (6), and the other end is located in the air channel (1). A plurality of evenly distributed gear teeth (12) are arranged on the end cover. A gear (15) is arranged in the air channel (1). The gear (15) is provided with a gear shaft (22). The gear (15) and the gear teeth (12) can cooperate with each other. The air channel (1) is provided with an inner wall gear shaft sleeve (21) and an outer wall gear shaft mounting seat (17). The outer wall gear shaft mounting seat (17) is a boss with a wall thickness greater than that of the air channel (1). The outer wall gear shaft mounting seat (17) is provided with a gear shaft hole (24) and is provided on the outer wall surface. A dial (19) is provided. One end of the gear shaft (22) is sleeved in the gear shaft sleeve (21) on the inner wall, and the other end passes through the gear shaft hole (24) and extends out a section and can rotate freely. A sealing ring (23) is provided at the connection between the gear shaft hole (24) and the gear shaft (22) to prevent air leakage. A rocker (17) and a pointer (18) are provided at one end of the gear shaft (22) extending out of the wheel shaft mounting seat (17). The pointer (18) rotates with the rotation of the gear shaft (22) and points to the range of the dial (19); the axial direction of the gear shaft (22) is perpendicular to the central axial direction of the air passage (1).

2. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The number of the swirl blades (14) is 4 to 15.

3. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The swirl angle of the swirl blade (14) is 20° to 60°.

4. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The angle between the end cover side wall surface (25) and the central axis direction of the air channel (1) is 30° to 90°.

5. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The angle between the peripheral oblique injection hole (9) and the central axis direction of the air channel (1) is 10° to 60°.

6. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The number of the peripheral oblique injection holes (9) is 4 to 20.

7. The adjustable end cover full premixed low nitrogen burner according to claim 1, characterized in that: The number of the inner ring axial flow injection holes (10) is 4 to 20.

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