Circulating air cooling plane low-nitrogen combustor

Abstract

The utility model discloses a circulating air cooling plane low-nitrogen burner, which comprises a burner main body, a premixer, a buffer flexible joint, a cooling air return pipe and a fan, the fan is connected with an air inlet and outlet pipe, the air outlet pipe is connected with the premixer through the buffer flexible joint, and the premixer is connected with the burner main body; a premixing chamber, a cooling air supply channel and a cooling air return channel are formed in the premixer through an air distribution cylinder, the premixing chamber is provided with a uniform mixing conical core, and a gas distribution chamber communicated with the premixing chamber is arranged in the air distribution cylinder; a flat plate type honeycomb burning head is arranged in the combustor main body close to the outlet end; a uniform mixing chamber communicated with the premixing chamber is formed between the burning head and the inlet end of the combustor main body; a cooling channel is arranged in the burner body, a cooling calandria and a cooling air supply channel are arranged in the burner head, and the cooling channel, the cooling calandria, the cooling air return channel, the cooling air return pipe and the fan air inlet pipe are communicated. The low-nitrogen combustion furnace can ensure safe and sufficient combustion, has the functions of air quantity redistribution and cold air supplement, and can realize high-efficiency low-nitrogen combustion.

Description

Technical Field

[0001] The utility model relates to the technical field of burners, in particular to a circulating air-cooled flat low-nitrogen burner. Background Art

[0002] As an important equipment widely used in industrial production, the quality of the burner affects the amount of nitrogen oxides generated. The structure of the existing ordinary burner is to set a gas inlet and an air inlet on the shell, and the gas inlet is connected to a gas pipe leading to the combustion chamber. The gas and air introduced are mixed and discharged in the combustion chamber and ignited. The burner with this structure has a simple structure and function, and the emission of nitrogen oxides is large, which cannot meet the emission requirements of industrial production.

[0003] In order to achieve complete combustion of the mixed fuel and reduce the generation of gases such as NOx and CO, existing low-nitrogen burners are mostly designed based on the degree of mixing of fuel and air. The internal structure of the burner is too complicated, and the flame it produces is concentrated and the temperature is high, which easily causes flashback and the low-nitrogen combustion effect is unsatisfactory. This traditional low-nitrogen burner also does not have temperature detection and air volume redistribution functions, and cannot achieve efficient low-nitrogen combustion. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a circulating air-cooled flat low-nitrogen burner, aiming to solve the technical problems existing in the prior art that the internal structure design of the burner is too complicated, the flame is concentrated and the temperature is high, and flashback is easy to occur, and at the same time, the burner does not have the functions of temperature detection and air volume redistribution, and cannot achieve efficient low-nitrogen combustion.

[0005] The technical solution of the utility model is: a circulating air-cooled flat low-nitrogen burner, comprising a burner body, a premixer, a buffer flexible joint, a cooling return air duct, and a fan, wherein the inlet of the fan is connected to the air inlet duct, and the outlet is connected to the air outlet duct, the air outlet duct is connected to the inlet end of the premixer through the buffer flexible joint, and the outlet end of the premixer is connected to the burner body;

[0006] The interior of the premixer is provided with an air volume distribution cylinder, the inlet end of which at least partially fits the inner wall of the premixer and forms a premixing chamber in the middle, a cooling air supply channel in the upper part and a cooling return air channel in the lower part between the inlet end and the premixer, a uniform mixing cone is provided in the premixing chamber, and the inner wall of the air volume distribution cylinder is hollow to form a gas distribution chamber connected to the premixing chamber; the inlet air of the premixer is divided into premixed air and cooling air through the air volume distribution cylinder and enters the premixing chamber and the cooling air supply channel respectively, and the premixed air is mixed with the natural gas sent into the gas distribution chamber to form a premixed gas;

[0007] A flat honeycomb burner head is provided inside the burner body near the outlet end, and a mixing chamber connected to the premixing chamber is formed between the flat honeycomb burner head and the inlet end of the burner body. The premixed gas in the premixing chamber enters the mixing chamber for secondary mixing and then is discharged through the flat honeycomb burner head; the inner wall of the burner body is hollow to form a cooling channel, and a cooling exhaust pipe is provided inside the flat honeycomb burner head. The cooling air supply channel, cooling channel, cooling exhaust pipe, and cooling return air channel are connected to each other, one end of the cooling return air pipe is connected to the premixer and connected to the cooling return air channel, and the other end is connected to the air inlet pipe of the fan to realize cooling air circulation.

[0008] Furthermore, the inlet end of the air volume distribution cylinder in the utility model is in the shape of a contraction opening, the inclined lower surface of the contraction opening fits against the inner wall of the premixer to achieve airflow blocking, and the mouth of the contraction opening is also connected to a dividing plate extending horizontally toward the buffer flexible joint for dividing the airflow.

[0009] Furthermore, the air volume distribution cylinder described in the utility model has a plurality of vent holes on its inner wall which connect the gas distribution chamber and the premixing chamber. The air volume distribution cylinder is also connected to a gas inlet pipe which penetrates into the premixer and is connected to the gas distribution chamber.

[0010] Furthermore, the cooling channel described in the utility model includes a cooling air distribution chamber respectively arranged at the upper part and the cooling air collection chamber at the lower part of the flat honeycomb burner head, a cooling air inlet channel connected to the cooling air distribution chamber, and a cooling air outlet channel connected to the cooling air collection chamber. The upper and lower ends of the cooling exhaust pipe extend up and down to connect with the cooling air distribution chamber and the cooling air collection chamber respectively.

[0011] Furthermore, the burner described in the utility model also includes a cold air supply duct, which is arranged on the surface of the premixer and the burner body, the inlet end of the cold air supply duct extends toward the inlet end of the premixer and is connected with the inlet end of the premixer, the outlet end of the cold air supply duct extends toward the outlet end of the burner body and is connected with a cooling air distribution chamber, an air volume switch is provided in the cold air supply duct, and a temperature sensor for controlling the air volume switch is provided in the cooling air distribution chamber.

[0012] Furthermore, the air volume switch described in the utility model includes a rolling body that is sealed and rotatably installed in the cold air supply air duct, and a driving mechanism that drives the rolling body to rotate. A ventilation channel is provided on the rolling body, and the ventilation channel can be opened or closed by rotating the rolling body in cooperation with the cold air supply air duct.

[0013] Furthermore, the rolling body described in the utility model is cylindrical, and an upper sealing cylinder and a lower sealing cylinder arranged up and down are rotatably installed inside the cold air supply air duct. The rolling body is at least partially embedded in the cold air supply air duct and fits tightly with the upper and lower sealing cylinders, and the two end faces of the rolling body are respectively fitted with the inner walls on both sides of the cold air supply air duct.

[0014] Furthermore, in the utility model, both ends of each sealing column are mounted on floating blocks via a rotating shaft, and the floating blocks are mounted in the cold air supply duct via a spring. The spring provides a force for pressing the rolling body for the sealing column to ensure a tight fit.

[0015] Furthermore, the driving mechanism described in the utility model includes a motor installed on the outside of the cold air supply duct through a side bracket, a driving gear connected to the motor output shaft, a driven gear meshing with the driving gear, and a transmission shaft that passes through the cold air supply duct and connects the driven gear and the rolling body.

[0016] Furthermore, the utility model provides one or more ventilation channels, and the rotation of the rolling body can drive the ventilation channels to rotate so that the corresponding two ends of the ventilation channels are located on the same side or are covered and sealed in the cold air supply duct.

[0017] Compared with the prior art, the utility model has the following advantages:

[0018] 1) When the low-nitrogen burner of the utility model is working, the air outlet of the fan is sent into one end of the premixer, and is divided into two paths under the action of the air volume distribution cylinder. One path enters the premixing chamber, mixes with the natural gas introduced into the gas distribution chamber to form a premixed gas, and is discharged through the flat honeycomb burner after secondary mixing in the uniform mixing chamber. The premixed gas is divided by the flat honeycomb burner to form countless tiny flames, which can achieve the effect of low-nitrogen combustion; the other path enters the cooling air supply channel, and the cooling air enters the burner body after a cycle, and cools the flame through the cooling exhaust pipe, thereby suppressing the generation of high-temperature nitrogen oxides, further achieving low-nitrogen combustion. At the same time, the cooling air is heated by the flame and circulated to the fan again for use, which promotes combustion, further improves the combustion completeness of the premixed gas, and achieves efficient low-nitrogen combustion.

[0019] 2) In the utility model, since the cooling exhaust pipe is embedded in the flat honeycomb burner head, the temperature of the contact surface between the flat honeycomb burner head and the cooling exhaust pipe is reduced, so that the flame generated on the outer side of the flat honeycomb burner head will not propagate back to the inside, thereby effectively avoiding the occurrence of backfire, which is safe and reliable.

[0020] 3) In the utility model, a cold air supply duct and a temperature sensor are added to the original low-nitrogen burner, and an air volume switch is designed in the duct. When the cooling effect is insufficient, the air volume redistribution and cold air supply functions can be achieved by opening the air volume switch, thereby further realizing efficient low-nitrogen combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the utility model;

[0022] Figure 2This is a schematic diagram of the open state of the air volume switch described in the utility model;

[0023] Figure 3 This is a specific installation diagram of the air volume switch described in the utility model;

[0024] Figure 4 This is a simplified diagram of the closed state of the air volume switch described in the utility model.

[0025] in:

[0026] 1. Burner body; 1.1. Flat honeycomb burner head; 1.2. Mixing chamber; 1.3. Cooling exhaust pipe; 1.4. Cooling air distribution chamber; 1.5. Cooling air collection chamber; 1.6. Cooling air inlet channel; 1.7. Cooling air outlet channel;

[0027] 2. Premixer; 2.1. Premixing chamber; 2.2. Cooling air supply channel; 2.3. Cooling return air channel; 2.4. Mixing cone core; 2.5. Gas distribution chamber; 2.6. Gas inlet pipe;

[0028] 3. Buffer soft joint;

[0029] 4. Cooling return air duct;

[0030] 5. Fan; 5.1. Air inlet pipe; 5.2. Air outlet pipe;

[0031] 6. Air volume distribution cylinder;

[0032] 7. Split plate;

[0033] 8. Cold air supply air duct; 8.1. Upper sealing cylinder; 8.2. Lower sealing cylinder; 8.3. Rotating shaft; 8.4. Floating block; 8.5. Spring;

[0034] 9. Air volume switch; 9.1. Rolling element; 9.2. Driving mechanism; 9.2.1. Side bracket; 9.2.2. Motor; 9.2.3. Driving gear; 9.2.4. Driven gear; 9.2.5. Transmission shaft; 9.3. Ventilation channel;

[0035] 10. Temperature sensor. DETAILED DESCRIPTION

[0036] The specific implementation of the utility model is described in detail below with reference to the accompanying drawings.

[0037] Example:

[0038] The accompanying drawings show a specific implementation of a circulating air-cooled flat low-nitrogen burner of the utility model, as shown in FIG. Figure 1It mainly includes a burner body 1, a premixer 2, a buffer flexible joint 3, a cooling return air duct 4, and a fan 5. The inlet of the fan 5 is connected to the air inlet duct 5.1, and the outlet is connected to the air outlet duct 5.2. The air outlet duct 5.2 is connected to the inlet end of the premixer 2 through the buffer flexible joint 3, and the outlet end of the premixer 2 is connected to the burner body 1.

[0039] Among them, an air volume distribution tube 6 is provided inside the premixer 2, and the inlet end of the air volume distribution tube 6 is in a contraction shape. The inclined lower surface of the contraction is in contact with the inner wall of the premixer 2 to achieve airflow blocking. The mouth of the contraction is connected to a dividing plate 7 extending horizontally toward the buffer flexible joint 3 for dividing the airflow, and the outlet end of the air volume distribution tube 6 is open.

[0040] Three regional spaces are formed between the air volume distribution cylinder 6 and the premixer 2, namely the premixing chamber 2.1 located in the middle, the cooling air supply channel 2.2 located in the upper part, and the cooling return air channel 2.3 located in the lower part. Among them, the premixing chamber 2.1 is used for gas mixing, and a uniform mixing cone core 2.4 is arranged in the premixing chamber 2.1; the air volume distribution cylinder 6 is connected with a gas inlet pipe 2.6, and the inner wall of the air volume distribution cylinder 6 is hollow to form a gas distribution chamber 2.5. The gas inlet pipe 2.6 penetrates into the premixer 2 and is connected to the gas distribution chamber 2.5, and the natural gas is delivered into the gas distribution chamber 2.5; a plurality of vents are opened on the inner wall of the air volume distribution cylinder 6, and the gas distribution chamber 2.5 and the premixing chamber 2.1 are connected through the vents, and the natural gas can enter the premixing chamber 2.1.

[0041] The inlet air of the premixer 2 flows through the dividing plate 7 and the air volume distribution cylinder 6 in two ways. One way enters the premixing chamber 2.1 as premixed air and mixes with the natural gas sent from the gas distribution chamber 2.5 to form premixed gas. The other way enters the cooling air supply channel 2.2 as cooling air. The cooling return air channel 2.3 is used for the recovery and circulation of the cooling air after use.

[0042] The inlet end of the burner body 1 is connected to the outlet end of the premixer 2. A flat honeycomb burner head 1.1 is provided inside the burner body 1 near its outlet end. The length of the flat honeycomb burner head 1.1 extends up and down. A mixing chamber 1.2 connected to the premixing chamber 2.1 is formed between the flat honeycomb burner head 1.1 and the inlet end of the burner body 1, that is, the mixing chamber 1.2 is connected to the open outlet end of the air volume distribution tube 6. The premixed gas in the premixing chamber 2.1 can enter the mixing chamber 1.2 for secondary mixing and then be discharged through the flat honeycomb burner head 1.1.

[0043] The inner wall of the burner body 1 is hollow to form a cooling channel, which includes a cooling air distribution chamber 1.4 and a cooling air collection chamber 1.5 respectively arranged at the upper part of the flat honeycomb burner 1.1, a cooling air inlet channel 1.6 connected to the cooling air distribution chamber 1.4, and a cooling air outlet channel 1.7 connected to the cooling air collection chamber 1.5. A cooling exhaust pipe 1.3 is arranged inside the flat honeycomb burner 1.1, and the upper and lower ends of the cooling exhaust pipe 1.3 extend up and down to connect with the cooling air distribution chamber 1.4 and the cooling air collection chamber 1.5. Furthermore, the cooling air inlet channel 1.6 is also interconnected with the cooling air supply channel 2.2, and the cooling air outlet channel 1.7 is also interconnected with the cooling return air channel 2.3. One end of the cooling return air pipe 4 is connected to the premixer 2 and connected with the cooling return air channel 2.3, and the other end is connected to the air inlet pipe 5.1 of the fan 5 to realize the circulation of the cooling air.

[0044] When the low nitrogen burner with the above structure works specifically, Figure 1 Natural air (as shown by arrow a) enters through the air inlet pipe 5.1 of the fan 5, and is pressurized by the power of the fan 5. The fan exhaust air (as shown by arrow b) is sent to the buffer flexible joint 3 through the air outlet pipe 5.2, and then enters the premixer 2. The airflow is first divided by the dividing plate 7, and under the action of the air volume distribution cylinder 6, one path is used as premixed air (as shown by arrow c) to enter the premixing chamber 2.1, and the other path is used as cooling air (as shown by arrow d) to enter the cooling air supply channel 2.2. The premixed air enters the premixing chamber 2.1 and mixes with the natural gas. The natural gas (as shown by arrow e) enters the gas distribution chamber 2.5 from the gas inlet pipe 2.6 and enters the premixing chamber 2.1 after being evenly distributed to be evenly mixed with the premixed air to form a premixed gas. The premixed gas (as shown by arrow f) enters the mixing chamber 1.2 for secondary mixing and is evenly distributed to the air inlet side of the flat honeycomb burner 1.1. The premixed gas passes through the honeycomb segmentation of the flat honeycomb burner 1.1 and is ignited and burned on the air outlet side of the flat honeycomb burner 1.1 to form a planar low-nitrogen flame. The other cooling air enters the burner body 1 through the cooling air supply channel 2.2, and first enters the cooling air distribution chamber 1.4 through the cooling air inlet channel 1.6, and evenly distributes the cooling air to the cooling exhaust pipe 1.3 buried in the flat honeycomb burner 1.1 to cool the flame. At the same time, the cooling air is heated by the flame and enters the cooling air collection chamber 1.5, and then enters the air inlet pipe 5.1 of the fan 5 through the cooling air outlet channel 1.7, the cooling return air channel 2.3 and the cooling return air pipe 4 for recycling, thereby further improving the combustion completeness of the premixed gas.

[0045] Furthermore, in this embodiment, the burner further includes a cold air supply duct 8 for realizing air volume redistribution and cold air supply functions. Specifically, the cold air supply duct 8 is arranged on the surface of the premixer 2 and the burner body 1, that is, it is extended along the surface of the premixer 2 and the burner body 1, such as Figure 1The inlet end of the cold air supply duct 8 extends to the inlet end of the premixer 2 and communicates with the inlet end of the premixer 2. It can be connected to the inlet end of the cold air supply duct 8 by opening the inlet end of the premixer 2. The outlet end of the cold air supply duct 8 extends to the outlet end of the burner body 1 and communicates with the cooling air distribution chamber 1.4. It can be connected to the outlet end of the cold air supply duct 8 by opening the cooling air distribution chamber 1.4. The function of the cold air supply duct 8 is the same as that of the cooling air supply channel 2.2. When opened, it can increase the cooling air supply volume.

[0046] An air volume switch 9 is provided in the cold air supply duct 8, and a temperature sensor 10 for controlling the air volume switch 9 is provided in the cooling air distribution chamber 1.4. When the temperature sensor 10 detects that the cooling effect is insufficient, the cold air supply duct 8 can be opened by turning on the air volume switch 9 to supply cooling air.

[0047] In this embodiment, the specific structure of the air volume switch 9 is combined with Figure 2 , Figure 3 As shown, it mainly includes a rolling body 9.1 that is sealed and rotatably installed in the cold air supply air duct 8. The rolling body 9.1 is cylindrical, and the left and right end surfaces of the rolling body 9.1 are respectively in contact with the inner walls of the cold air supply air duct 8 on both sides, and the upper and lower parts of the rolling body 9.1 are at least partially embedded in the cold air supply air duct 8. An upper sealing cylinder 8.1 and a lower sealing cylinder 8.2 are also rotatably installed inside the cold air supply air duct 8. The upper sealing cylinder 8.1 and the lower sealing cylinder 8.2 are respectively arranged at the upper and lower positions of the rolling body 9.1 and are tightly in contact with the rolling body 9.1, ensuring that the rotation of the rolling body 9.1 is smoother while improving the sealing effect of the duct.

[0048] Specifically, the upper sealing cylinder 8.1 and the lower sealing cylinder 8.2 are installed in the same manner, and both ends of each sealing cylinder are installed on the floating block 8.4 through the rotating shaft 8.3. The sealing cylinder can rotate around the rotating shaft 8.3, and the floating block 8.4 is installed in the cold air supply duct 8 by the spring 8.5. The force of the spring 8.5 acts on the floating block 8.4, and then is transmitted to the sealing cylinder through the rotating shaft 8.3, providing a force pressing against the rolling body 9.1 for the sealing cylinder to ensure that it is always closely fitted with the rolling body 9.1.

[0049] The rolling body 9.1 is driven to rotate by a driving mechanism 9.2, which includes a motor 9.2.2 installed on the outside of the cold air supply duct 8 through a side bracket 9.2.1, a driving gear 9.2.3 connected to the output shaft of the motor 9.2.2, a driven gear 9.2.4 meshing with the driving gear 9.2.3, and a transmission shaft 9.2.5 passing through the cold air supply duct 8 and connecting the driven gear 9.2.4 and the rolling body 9.1. The rotation of the rolling body 9.1 can drive the upper sealing cylinder 8.1 and the lower sealing cylinder 8.2 to rotate.

[0050] In this embodiment, Figure 2 , Figure 3 As shown, the rolling body 9.1 is provided with three ventilation channels 9.3, which are a middle ventilation channel arranged in the middle of the rolling body 9.1, and side ventilation channels symmetrically arranged on both sides of the middle ventilation channel. When the two ends of the ventilation channel 9.3 are respectively located at the front and rear sides of the rolling body 9.1, the wind can pass through, and the cold air supply duct 8 is in an open state. When the driving mechanism 9.2 drives the rolling body 9.1 to rotate 90°, the two ends of the three ventilation channels 9.3 are covered and sealed in the cold air supply duct 8, and the wind cannot pass through the rolling body 9.1, and the cold air supply duct 8 is in a closed state. Figure 4 As shown, the upper sealing column 8.1 and the lower sealing column 8.2 are not drawn, and the sealing columns do not affect the sealing effect of the cold air supply air duct 8 on the ventilation channel 9.3.

[0051] In addition, the number and position of the ventilation channels 9.3 can be adjusted as needed. It is only necessary to ensure that after the rolling body 9.1 rotates, the corresponding two ends of the ventilation channels 9.3 are located on the same side, or can be covered and sealed in the cold air supply duct 8 to prevent the circulation of wind.

[0052] The utility model adds a cold air supply air duct 8 and a temperature sensor 10 on the basis of the original low-nitrogen burner, and designs an air volume switch 9 in the duct. When the temperature sensor 10 detects that the cooling effect is insufficient, the driving mechanism 9.2 can be controlled to open the air volume switch 9, and the cold air supply air duct 8 is ventilated by using the ventilation channel 9.3, so that the wind entering the premixer 2 can be divided into a third path to pass into the cold air supply air duct 8 as a supplement to the cooling air of the cooling air supply channel 2.2, and sent together into the cooling air distribution chamber 1.4 for cooling air circulation, thereby increasing the cooling effect on the flame and improving the low-nitrogen combustion effect.

[0053] Of course, the above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any modifications made according to the spirit of the main technical solution of the utility model should be included in the protection scope of the utility model.

Claims

1. A circulating air-cooled flat low-nitrogen burner, characterized in that: It comprises a burner body (1), a premixer (2), a buffer flexible joint (3), a cooling return air pipe (4), and a fan (5); the inlet of the fan (5) is connected to an air inlet pipe (5.1), and the outlet is connected to an air outlet pipe (5.2); the air outlet pipe (5.2) is connected to the inlet end of the premixer (2) through the buffer flexible joint (3); and the outlet end of the premixer (2) is connected to the burner body (1); An air volume distribution cylinder (6) is provided inside the premixer (2). The inlet end of the air volume distribution cylinder (6) is at least partially attached to the inner wall of the premixer (2) and forms a premixing chamber (2.1) located in the middle, a cooling air supply channel (2.2) located in the upper part, and a cooling return air channel (2.3) located in the lower part between the inlet end and the premixer (2). A mixing cone core (2.4) is provided in the premixing chamber (2.1). The inner wall of the air volume distribution cylinder (6) is hollow to form a gas distribution chamber (2.5) connected to the premixing chamber (2.1). The inlet air of the premixer (2) is divided into premixed air and cooling air through the air volume distribution cylinder (6) and enters the premixing chamber (2.1) and the cooling air supply channel (2.2) respectively. The premixed air is mixed with the natural gas sent from the gas distribution chamber (2.5) to form a premixed gas. A flat honeycomb burner (1.1) is provided inside the burner body (1) near the outlet end, and a mixing chamber (1.2) connected to a premixing chamber (2.1) is formed between the flat honeycomb burner (1.1) and the inlet end of the burner body (1). The premixed gas in the premixing chamber (2.1) enters the mixing chamber (1.2) for secondary mixing and then passes through the flat honeycomb burner (1.1) to be discharged. The inner wall of the burner body (1) is hollow to form a cooling channel, and a cooling exhaust pipe (1.3) is provided inside the flat honeycomb burner (1.1). The cooling air supply channel (2.2), the cooling channel, the cooling exhaust pipe (1.3), and the cooling return air channel (2.3) are connected to each other. One end of the cooling return air pipe (4) is connected to the premixer (2) and connected to the cooling return air channel (2.3), and the other end is connected to the air inlet pipe (5.1) of the fan (5) to realize cooling air circulation.

2. A circulating air-cooled flat low-nitrogen burner according to claim 1, characterized in that: The inlet end of the air volume distribution cylinder (6) is in the shape of a contraction opening, the inclined lower surface of which is in contact with the inner wall of the premixer (2) to achieve airflow blocking, and the mouth of the contraction opening is also connected to a dividing plate (7) extending horizontally toward the buffer flexible joint (3) for dividing the airflow.

3. A circulating air-cooled flat low-nitrogen burner according to claim 1, characterized in that: The inner wall of the air volume distribution cylinder (6) is provided with a plurality of vent holes connecting the gas distribution chamber (2.5) and the premixing chamber (2.1). The air volume distribution cylinder (6) is also connected with a gas inlet pipe (2.6), which penetrates into the premixer (2) and is connected with the gas distribution chamber (2.5).

4. A circulating air-cooled flat low-nitrogen burner according to claim 1, characterized in that: The cooling channel comprises a cooling air distribution chamber (1.4) and a cooling air collection chamber (1.5) respectively arranged at the upper part of the flat honeycomb burner (1.1), a cooling air inlet channel (1.6) connected to the cooling air distribution chamber (1.4), and a cooling air outlet channel (1.7) connected to the cooling air collection chamber (1.5); the upper and lower ends of the cooling exhaust pipe (1.3) respectively extend up and down to be connected to the cooling air distribution chamber (1.4) and the cooling air collection chamber (1.5).

5. A circulating air-cooled flat low-nitrogen burner according to claim 4, characterized in that: The burner further comprises a cold air supply duct (8), which is arranged on the surface of the premixer (2) and the burner body (1), the inlet end of the cold air supply duct (8) extends toward the inlet end of the premixer (2) and is connected to the inlet end of the premixer (2), the outlet end of the cold air supply duct (8) extends toward the outlet end of the burner body (1) and is connected to the cooling air distribution chamber (1.4), an air volume switch (9) is arranged in the cold air supply duct (8), and a temperature sensor (10) for controlling the air volume switch (9) is arranged in the cooling air distribution chamber (1.4).

6. A circulating air-cooled flat low-nitrogen burner according to claim 5, characterized in that: The air volume switch (9) comprises a rolling body (9.1) which is sealed and rotatably mounted in a cold air supply duct (8), and a driving mechanism (9.2) which drives the rolling body (9.1) to rotate. A ventilation channel (9.3) is provided on the rolling body (9.1). The ventilation channel (9.3) can be opened or closed by rotating the rolling body (9.1) in cooperation with the cold air supply duct (8).

7. A circulating air-cooled flat low-nitrogen burner according to claim 6, characterized in that: The rolling body (9.1) is cylindrical, and an upper sealing cylinder (8.1) and a lower sealing cylinder (8.2) arranged vertically are rotatably mounted inside the cold air supply duct (8). The rolling body (9.1) is at least partially embedded in the cold air supply duct (8) and fits tightly with the upper and lower sealing cylinders. The two end surfaces of the rolling body (9.1) fit with the inner walls of the cold air supply duct (8) on both sides respectively.

8. The circulating air-cooled flat low-nitrogen burner according to claim 7 is characterized in that: Both ends of each sealing column are mounted on a floating block (8.4) via a rotating shaft (8.3). The floating block (8.4) is mounted in a floating manner inside the cold air supply duct (8) via a spring (8.5). The spring (8.5) provides a force for the sealing column to press against the rolling body (9.1) to ensure a tight fit.

9. The circulating air-cooled flat low-nitrogen burner according to claim 6, characterized in that: The driving mechanism (9.2) comprises a motor (9.2.2) mounted on the outside of the cold air supply duct (8) via a side bracket (9.2.1), a driving gear (9.2.3) connected to the output shaft of the motor (9.2.2), a driven gear (9.2.4) meshing with the driving gear (9.2.3) for transmission, and a transmission shaft (9.2.5) passing through the cold air supply duct (8) and connecting the driven gear (9.2.4) and the rolling body (9.1).

10. The circulating air-cooled flat low-nitrogen burner according to claim 6, characterized in that: The ventilation channel (9.3) is provided with one or more channels, and the rotation of the rolling body (9.1) can drive the ventilation channel (9.3) to rotate so that the corresponding two ends of the ventilation channel (9.3) are located on the same side or are covered and sealed in the cold air supply duct (8).

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