Environment-friendly low-nitrogen burner with flue gas internal circulation function and using method of environment-friendly low-nitrogen burner

Abstract

The invention discloses an environment-friendly low-nitrogen burner with flue gas internal circulation and a use method, and belongs to the technical field of low-nitrogen burners. The environment-friendly low-nitrogen burner comprises a fan, a burning head, a fuel inlet pipe and a controller, the combustion head comprises an outer cylinder, a filter, a heat exchanger, a condenser, a mixer and a combustion cylinder, wherein the filter, the heat exchanger, the condenser and the mixer are arranged in the outer cylinder and communicated in sequence; the mixer is used for mixing the air input by the fan with the recovered flue gas and guiding the mixed gas into the combustion cylinder; temperature sensors are arranged at an inlet and an outlet of the heat exchanger, a flow speed control assembly is arranged in an outlet of the heat exchanger, circulating flue gas is cooled through the heat exchanger, heat of the circulating flue gas is recycled, the temperature when the flue gas is mixed with air is not too high, and meanwhile heat consumption is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of low - nitrogen burners, and specifically to an environment - friendly low - nitrogen burner with flue gas internal circulation and a usage method thereof. Background Art

[0002] During the combustion process of traditional burners, due to reasons such as high combustion temperature and uneven oxygen concentration distribution in the combustion area, a large amount of nitrogen oxides (NOx) are easily generated. Nitrogen oxides are one of the main pollutants causing air pollution. They can trigger environmental problems such as acid rain and photochemical smog, and cause serious harm to human health and the ecological environment. In order to reduce the emission of NOx, the flue gas recirculation technology is usually adopted. By sending part of the flue gas back to the combustion area, the combustion temperature and oxygen concentration are reduced, so as to achieve the purpose of reducing the generation of NOx.

[0003] However, in practical applications, the flue gas recirculation technology has certain limitations. If the flue gas after heat recovery is used for circulation, due to the low temperature of the flue gas, the low - temperature flue gas will reduce the average temperature of the combustion area, thus slowing down the combustion reaction rate, which may lead to incomplete combustion, reduce the combustion efficiency, and may increase fuel consumption. If the high - temperature flue gas generated during the combustion process is directly used for recirculation, due to the too high temperature of the flue gas, the too high temperature will weaken the effect of inhibiting the generation of NOx, and at the same time, the heat in the flue gas will be wasted, resulting in waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to provide an environment - friendly low - nitrogen burner with flue gas internal circulation and a usage method thereof, so as to solve certain problems existing in the flue gas recirculation technology mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: An environment - friendly low - nitrogen burner with flue gas internal circulation, including: a blower, a combustion head, a fuel inlet pipe and a controller. The combustion head includes an outer cylinder, a filter, a heat exchanger, a condenser, a mixer arranged in the outer cylinder and connected in sequence, and a combustion cylinder connected to the filter through a circulation pipeline.

[0006] The mixer is used to mix the air input by the blower with the recycled flue gas and introduce it into the combustion cylinder.

[0007] Temperature sensors are arranged at both the inlet and outlet of the heat exchanger. A flow rate control component is arranged inside the outlet of the heat exchanger. The flow rate control component is used to delay the passing speed of the flue gas through the heat exchanger when the temperature sensor detects that the temperature of the flue gas entering the heat exchanger is greater than a preset value. The controller is used to control the condenser to work to perform secondary cooling on the flue gas discharged from the heat exchanger when the temperature sensor detects that the temperature of the flue gas discharged from the heat exchanger is greater than a preset value.

[0008] Preferably, the heat exchanger includes a first outer shell and a first heat exchange pipe disposed within the first outer shell;

[0009] Wherein, the flow rate control assembly includes a mounting groove provided at the outlet of the first outer shell, a stopper slidably disposed within the mounting groove, and a driving assembly for driving the movement of the stopper.

[0010] Preferably, the first outer shell includes a first housing, a second housing, and a driving member for changing the distance between the first housing and the second housing;

[0011] Wherein, the stopper is disposed on the second housing.

[0012] Preferably, the driving assembly includes a screw rod screwed to the stopper, a first gear rotatably disposed within the mounting groove and connected to the screw rod, and a driving rack connected to the first housing and meshing with the first gear.

[0013] Preferably, the outlet of the second housing is communicated with the inlet of the condenser through a corrugated pipe.

[0014] Preferably, the condenser includes a second outer shell, a second heat exchange pipe disposed within the second outer shell, a baffle slidably disposed within the second outer shell for covering the second heat exchange pipe, and a driving device for driving the movement of the baffle.

[0015] Preferably, the mixer includes a mixing tank, and a first partition and a second partition are disposed within the mixing tank. The first partition and the second partition divide the inner cavity of the mixing tank into a mixing chamber, a flue gas storage chamber, and an air storage chamber;

[0016] Wherein, openings are provided between the flue gas storage chamber and the mixing chamber, and between the air storage chamber and the mixing chamber. Solenoid valves are provided on the openings, and flow sensors are provided at the outlets of the solenoid valves.

[0017] Preferably, a push plate is slidably disposed within the flue gas storage chamber. A second gear is provided on the mixing tank, and a first rack and a second rack respectively meshing with the second gear are provided. The second rack is connected to the second housing, and the first rack is connected to the push plate through a push rod.

[0018] Preferably, the push rod includes a first rod body, a second rod body slidably disposed on the first rod body, and an elastic member disposed between the first rod body and the second rod body. A limiting member for restricting the movement position of the push plate is provided within the flue gas storage chamber.

[0019] Preferably, a method for using an environmentally friendly low-nitrogen burner using flue gas internal circulation as described above includes the following steps:

[0020] S1: The fan adds air into the combustion cylinder, and at the same time, the fuel inlet pipe adds fuel into the combustion cylinder for combustion;

[0021] S2: After a part of the flue gas generated by combustion enters the filter through the circulation pipeline for filtration, it is introduced into the heat exchanger for cooling. The temperature sensor detects the temperature of the flue gas entering the heat exchanger. If the flue gas temperature is greater than the preset value, the flow rate control component delays the speed of the flue gas passing through the heat exchanger. Otherwise, the flue gas is normally discharged from the heat exchanger.

[0022] S3: The temperature sensor detects the temperature of the flue gas discharged from the heat exchanger. If the flue gas temperature is greater than the preset value, the controller controls the condenser to work for secondary cooling of the flue gas. Otherwise, the condenser does not cool the flue gas.

[0023] S4: The flue gas passing through the condenser enters the mixer, mixes with the air input by the fan, and then enters the combustion cylinder.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The heat exchanger cools the circulating flue gas and recovers its heat, so that the temperature of the flue gas when mixed with air is not too high, while avoiding heat consumption. And the temperature sensor detects the temperature of the flue gas entering and leaving the heat exchanger. When it detects that the temperature of the flue gas entering the heat exchanger is greater than the preset value, it delays the speed of the flue gas passing through the heat exchanger. When it detects that the temperature of the flue gas discharged from the heat exchanger is greater than the preset value, it controls the condenser to work for secondary cooling of the flue gas discharged from the heat exchanger, ensuring that the temperature of the flue gas mixed with air is not too high, so that the flue gas can effectively inhibit the generation of NOx. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the environment-friendly low-nitrogen burner of the present invention;

[0027] Figure 2 It is a schematic cross-sectional structure diagram of the burner head of the present invention;

[0028] Figure 3 It is a schematic connection structure diagram of the combustion cylinder and the circulation pipeline of the present invention;

[0029] Figure 4 For the present invention Figure 3 The enlarged schematic diagram of the structure at A in;

[0030] Figure 5 It is a schematic cross-sectional connection structure diagram of the first housing and the second housing of the present invention;

[0031] Figure 6 For the present invention Figure 5 The enlarged schematic diagram of the structure at B in;

[0032] Figure 7 It is a schematic cross-sectional structure diagram of the mixer of the present invention;

[0033] Figure 8 This is a schematic diagram of the connection structure between the push rod and the push plate of the present invention.

[0034] In the figure: 1, fan; 2, burner head; 21, outer cylinder; 22, combustion cylinder; 23, circulation pipeline; 24, filter; 25, heat exchanger; 251, first housing; 2511, first shell; 2512, second shell; 2513, installation groove; 2514, stop block; 2515, screw; 2516, driving rack; 2517, first gear; 2518, driving member; 252, first heat exchange pipeline; 26, condenser; 261, second housing; 262, second heat exchange pipeline; 263, baffle; 27, mixer; 271, mixing box; 272, first partition; 273, second partition; 274, push plate; 275, push rod; 2751, first rod body; 2752, second rod body; 2753, elastic member; 276, first rack; 277, second gear; 278, second rack; 279, solenoid valve; 2710, limiting member; 2701, flue gas storage cavity; 2702, air storage cavity; 2703, mixing cavity; 28, bellows; 29, temperature sensor; 3, fuel inlet pipe; 4, controller. Specific embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment 1

[0037] Please refer to Figure 1 , Figure 2 and Figure 3, An environment-friendly low-nitrogen burner with flue gas internal circulation, comprising: a fan 1, a combustion head 2, a fuel inlet pipe 3 and a controller 4 (PLC controller); the combustion head 2 includes an outer cylinder 21, a circulation pipe 23, a combustion cylinder 22, and a filter 24, a heat exchanger 25, a condenser 26, and a mixer 27 provided in the inner cavity of the outer cylinder 21; the outer cylinder 21 is installed at the outlet end of the fan 1, the combustion cylinder 22 is installed at one end of the outer cylinder 21 away from the fan 1, a spray head and an ignition device (such as a spark plug) are installed inside the combustion cylinder 22, one end of the circulation pipe 23 is communicated with the outlet end of the combustion cylinder 22, the other end of the circulation pipe 23 is communicated with the filter 24, the outlet of the filter 24 is communicated with the inlet of the shell of the heat exchanger 25 through a pipe, the outlet of the shell of the heat exchanger 25 is communicated with the inlet of the condenser 26, the outlet of the condenser 26 is communicated with the mixer 27 through a pipe, the mixer 27 is communicated with the air outlet of the fan 1, and the gas outlet of the mixer 27 is communicated with the spray head inside the combustion cylinder 22 through a conduit; the outlet of the fuel inlet pipe 3 is communicated with the conduit.

[0038] It should be noted that heat insulation layers are provided on the outer sides of the heat exchanger 25 and the condenser 26, and the heat insulation layers can be made of fiberglass insulation cotton, so that the heat exchanger 25 and the condenser 26 are not affected by the combustion of the combustion cylinder 22.

[0039] Please refer to Figure 3 、 Figure 5 and Figure 6 , the heat exchanger 25 includes a first outer shell 251 and a first heat exchange pipe 252 provided inside the first outer shell 251; temperature sensors 29 are provided in both the inlet and outlet of the first outer shell 251; a flow rate control component is provided in the outlet of the first outer shell 251.

[0040] Among them, the flow rate control component includes an installation groove 2513 opened on the inner side wall of the outlet of the first outer shell 251, a block 2514 slidably arranged in the installation groove 2513, and a driving component for driving the block 2514 to move.

[0041] A method for using an environment-friendly low-nitrogen burner with flue gas internal circulation is as follows:

[0042] First, the fan 1 adds air into the combustion cylinder 22, and at the same time, fuel enters the inside of the combustion cylinder 22 from the fuel inlet pipe 3, and the ignition device ignites, so that the fuel burns inside the combustion cylinder 22.

[0043] Second, the flue gas generated by combustion moves towards the outlet of the combustion cylinder 22. A part of the flue gas enters the next process, and a part of the flue gas enters the filter 24 through the circulation pipeline 23, is filtered, and then is introduced into the heat exchanger 25 for temperature reduction. The temperature sensor 29 detects the temperature of the flue gas entering the heat exchanger 25. If the flue gas temperature is greater than the preset value (the temperature value set by the user), the flow rate control component delays the speed of the flue gas passing through the heat exchanger 25, increases the residence time of the flue gas inside the first housing 251, ensures an increased temperature drop of the flue gas, and vice versa, the flue gas is normally discharged from the heat exchanger 25;

[0044] Third, the temperature sensor 29 detects the temperature of the flue gas discharged from the heat exchanger 25. If the flue gas temperature is greater than the preset value (the preset value set by the user, and this preset value is lower than the preset value at the inlet), the controller 4 controls the condenser 26 to work to cool the flue gas secondarily, and vice versa, the condenser 26 does not cool the flue gas;

[0045] Fourth, the flue gas passing through the condenser 26 enters the mixer 27, is mixed with the air input by the blower 1, and then enters the combustion cylinder 22, and then the operation is repeated to reduce NOx generated during combustion.

[0046] It should be noted that in order to enable the flue gas to enter the circulation pipeline 23, a device for extracting flue gas, such as a induced draft fan, is installed.

[0047] In this embodiment, as a further optimized solution, please refer to Figure 4 、 Figure 5 and Figure 6 , the first housing 251 includes a first housing body 2511, a second housing body 2512, and a driving member 2518 (such as an electric telescopic rod). The inlet is on the first housing body 2511, and the outlet is on the second housing body 2512. Both ends of the driving member are respectively connected to the side walls of the first housing body 2511 and the second housing body 2512; the first heat exchange pipeline 252 is arranged on the first housing body 2511. A ring-shaped mounting block is provided on the side of the second housing body 2512 facing the first housing body 2511, and a ring-shaped groove is formed on the side of the first housing body 2511 facing the second housing body 2512. The ring-shaped mounting block is inserted into the ring-shaped groove; when the temperature sensor 29 at the inlet detects that the temperature of the flue gas entering the interior of the first housing 251 is greater than the preset value, the controller 4 controls the driving member 2518 to work and extend, so that the first housing body 2511 and the second housing body 2512 move away from each other, to increase the internal space of the first housing 251, extend the residence time of the flue gas inside the first housing 251, increase the heat exchange time of the flue gas, and increase the temperature drop of the flue gas.

[0048] It should be noted that when the temperature of the flue gas entering the heat exchanger 25 is detected to exceed the preset value, the controller 4 will also calculate the exceeded value. According to the magnitude of the exceeded value, the controller 4 adjusts the elongation amplitude of the driving member 2518 so that the increased amplitude inside the first housing 251 is positively correlated with the magnitude of the exceeded value of the flue gas temperature. The specific elongation ratio is set according to the actual needs of the user.

[0049] It should also be noted that when both ends of the first heat exchange pipe 252 pass through the first housing 2511, they do not pass through the annular mounting block to prevent the first heat exchange pipe 252 from hindering the movement of the annular mounting block inside the annular groove.

[0050] In this embodiment, as a further optimized solution, please refer to Figure 6 , the driving assembly includes a screw 2515, a first gear 2517 and a driving rack 2516; the first gear 2517 is rotatably arranged in the inner cavity of the mounting groove 2513, the screw 2515 is arranged on the first gear 2517 (both are coaxial), a threaded hole is opened on the side wall of the stop block 2514, and one end of the screw 2515 away from the first gear 2517 is screwed into the inner cavity of the threaded hole. The driving rack 2516 is arranged on the first housing 2511, and the length extension direction of the driving rack 2516 is the same as the moving direction of the second housing 2512. The driving rack 2516 meshes with the first gear 2517; when the driving member 2518 drives the second housing 2512 to move away from the first housing 2511, the first gear 2517 moves together with the second housing 2512, so that the driving rack 2516 rotates while walking on the first gear 2517, driving the screw 2515 to rotate, and driving the stop block 2514 to move into the outlet of the second housing 2512 to reduce the size of the outlet and slow down the speed of the flue gas discharged from the inside of the first housing 251; and the movement of the stop block 2514 utilizes the power when the second housing 2512 moves.

[0051] In this embodiment, as a further optimized solution, please refer to Figure 3 and Figure 4 , the outlet of the second housing 2512 is communicated with the inlet of the condenser 26 through a corrugated pipe 28; through the expansion and contraction of the corrugated pipe 28, the movement of the second housing 2512 is not restricted.

[0052] In this embodiment, as a further optimized solution, please refer to Figure 4, the condenser 26 includes a second housing 261, a second heat exchange pipe 262 disposed inside the second housing 261, a baffle 263 slidably disposed in the inner cavity of the second housing 261, and a driving device (such as an electric telescopic rod) for driving the movement of the baffle 263. The baffle 263 is C-shaped, the baffle 263 covers the second heat exchange pipe 262, and a heat insulation layer (such as fiberglass insulation cotton) is provided on the baffle 263; when the condenser 26 does not need to work, the flue gas discharged from the heat exchanger 25 enters the inner cavity of the second housing 261. Due to the blocking of the baffle 263, the flue gas does not contact the second heat exchange pipe 262 and is directly discharged; when the condenser 26 needs to work, the driving device drives the baffle 263 to move (as shown in Figure 4 , the C-shaped baffle 263 moves downward), releasing the isolation of the second heat exchange pipe 262. When the flue gas enters the inner cavity of the second housing 261, it will contact the second heat exchange pipe 262 and exchange heat with the heat exchange medium inside the second heat exchange pipe 262 to further reduce the temperature of the flue gas.

[0053] Embodiment 2

[0054] As a further optimized solution of Embodiment 1, please refer to Figure 3 and Figure 7 , the mixer 27 includes a mixing box 271. A first partition 272 and a second partition 273 are provided in the mixing box 271. The first partition 272 and the second partition 273 form a T shape. The first partition 272 and the second partition 273 divide the inner cavity of the mixing box 271 into a flue gas storage cavity 2701, an air storage cavity 2702, and a mixing cavity 2703. The flue gas storage cavity 2701 is communicated with the outlet of the condenser 26, the air storage cavity 2702 is communicated with the air outlet of the fan 1, and the mixing cavity 2703 is communicated with the injection head of the combustion cylinder 22; openings are provided between the flue gas storage cavity 2701 and the mixing cavity 2703, and between the air storage cavity 2702 and the mixing cavity 2703. Solenoid valves 279 are installed on both openings, and flow sensors (gas flow sensors) are provided at the outlets of the two solenoid valves 279; the air output by the fan 1 will enter the inner cavity of the air storage cavity 2702, and the flue gas discharged from the condenser 26 enters the flue gas storage cavity 2701 for storage; when the solenoid valve 279 is opened, the air inside the air storage cavity 2702 and the flue gas inside the flue gas storage cavity 2701 enter the mixing cavity 2703 for mixing. During this process, the flow sensor will detect the amount of flue gas and air entering the mixing cavity 2703 and feedback it to the controller 4. When the amount of air or flue gas reaches the standard, the controller 4 can control the solenoid valve 279 to close to ensure the accurate mixing ratio of flue gas and air and ensure the best effect of suppressing NOx generation.

[0055] In this embodiment, as a further optimized solution, please refer to Figure 3 , Figure 4 andFigure 7 , a push plate 274 is slidably arranged in the inner cavity of the flue gas storage cavity 2701. A second gear 277 is rotatably arranged on the mixing box 271. A first rack 276 and a second rack 278 are slidably arranged on the mixing box 271. The first rack 276 and the second rack 278 are respectively located on both sides of the second gear 277 and mesh with the second gear 277. The second rack 278 is connected to the second housing 2512. The first rack 276 is connected to the push plate 274 through a push rod 275. When the second housing 2512 moves away from the first housing 2511, the second rack 278 will move along with it, driving the second gear 277 to rotate, so that the first rack 276 drives the push rod 275 and the push plate 274 to move, for increasing the pressure inside the flue gas storage cavity 2701 (because when the second housing 2512 moves away from the first housing 2511, the time for the flue gas to discharge from the first outer shell 251 will be delayed, which will cause the speed of the flue gas replenishing inside the flue gas storage cavity 2701 to decrease, thereby reducing the air pressure inside the flue gas storage cavity 2701), ensuring that the flow rate of the flue gas entering the mixing cavity 2703 will not decrease.

[0056] In this embodiment, as a further optimized solution, please refer to Figure 8 , the push rod 275 includes a first rod body 2751 and a second rod body 2752. An installation hole is opened at the end of the second rod body 2752. The first rod body 2751 is slidably inserted into the installation hole. An elastic member 2753 (spring) is installed between the first rod body 2751 and the installation hole. When the second housing 2512 moves and drives the push rod 275 to move, if the air pressure inside the flue gas storage cavity 2701 is relatively large, the push rod 275 will contract, so that the push plate 274 will not move, avoiding the air pressure inside the flue gas storage cavity 2701 from being too large and affecting the flue gas from entering the inside of the flue gas storage cavity 2701. A limiting member 2710 is arranged inside the flue gas storage cavity 2701. The limiting member 2710 is located on the moving path of the push plate 274, restricting the moving position of the push plate 274 so that it will not cross the communication area between the flue gas storage cavity 2701 and the condenser 26.

[0057] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly low-nitrogen burner with internal flue gas circulation, comprising: A fan (1), a combustion head (2), a fuel inlet pipe (3) and a controller (4), characterized in that the combustion head (2) comprises an outer cylinder (21), a filter (24) arranged in the outer cylinder (21) and connected in sequence, a heat exchanger (25), a condenser (26), a mixer (27), and a combustion cylinder (22) connected to the filter (24) through a circulation pipe (23); The mixer (27) is used to mix the air input by the fan (1) with the recovered flue gas and introduce the mixed air into the combustion tube (22); The inlet and outlet of the heat exchanger (25) are both provided with temperature sensors (29), and the outlet of the heat exchanger (25) is provided with a flow rate control component, and the flow rate control component is used to slow down the speed of the flue gas passing through the heat exchanger (25) when the temperature sensor (29) detects that the temperature of the flue gas entering the heat exchanger (25) is greater than a preset value. The controller (4) is used to control the condenser (26) to operate and perform secondary cooling on the flue gas discharged from the heat exchanger (25) when the temperature sensor (29) detects that the temperature of the flue gas discharged from the heat exchanger (25) is greater than a preset value.

2. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 1 is characterized in that: The heat exchanger (25) comprises a first shell (251) and a first heat exchange pipe (252) arranged in the first shell (251); The flow rate control component comprises a mounting groove (2513) arranged on the outlet of the first housing (251), a stopper (2514) slidably arranged in the mounting groove (2513), and a driving component for driving the stopper (2514) to move.

3. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 2 is characterized in that: The first housing (251) comprises a first shell (2511), a second shell (2512), and a driving member (2518) for changing the distance between the first shell (2511) and the second shell (2512); Wherein, the stopper (2514) is arranged on the second shell (2512).

4. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 3 is characterized in that: The driving assembly comprises a screw rod (2515) threadedly connected to the stopper (2514), a first gear (2517) rotatably arranged in the mounting groove (2513) and connected to the screw rod (2515), and a driving rack (2516) connected to the first housing (2511) and meshing with the first gear rod (2517).

5. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 3 is characterized in that: The outlet of the second shell (2512) is connected to the inlet of the condenser (26) through a bellows (28).

6. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 1 is characterized in that: The condenser (26) comprises a second shell (261), a second heat exchange pipe (262) arranged in the second shell (261), a baffle (263) slidably arranged in the second shell (261) and used to cover the second heat exchange pipe (262), and a driving device for driving the baffle (263) to move.

7. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 3 is characterized in that: The mixer (27) comprises a mixing box (271), wherein a first partition (272) and a second partition (273) are arranged in the mixing box (271), and the first partition (272) and the second partition (273) divide the inner cavity of the mixing box (271) into a mixing cavity (2703), a smoke storage cavity (2701) and an air storage cavity (2702); There are openings between the smoke storage chamber (2701) and the mixing chamber (2703), and between the air storage chamber (2702) and the mixing chamber (2703), and electromagnetic valves (279) are provided on the openings, and a flow sensor is provided at the outlet of the electromagnetic valve (279).

8. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 7 is characterized in that: A push plate (274) is slidably provided in the smoke storage chamber (2701), and a second gear (277) and a first rack (276) and a second rack (278) respectively meshed with the second gear (277) are provided on the mixing box (271); the second rack (278) is connected to the second shell (2512), and the first rack (276) is connected to the push plate (274) via a push rod (275).

9. The environmentally friendly low-nitrogen burner with internal flue gas circulation according to claim 8, characterized in that: The push rod (275) comprises a first rod body (2751), a second rod body (2752) slidably arranged on the first rod body (2751), and an elastic member (2753) arranged between the first rod body (2751) and the second rod body (2752); a limiting member (2710) for limiting the moving position of the push plate (274) is provided in the smoke storage chamber (2701).

10. A method for using the environmentally friendly low-nitrogen burner with internal flue gas circulation according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: The fan (1) adds air to the interior of the combustion tube (22), and at the same time, the fuel inlet pipe (3) adds fuel to the interior of the combustion tube (22) for combustion; S2: Part of the smoke generated by the combustion passes through the circulation pipe (23) and enters the filter (24) for filtration, and then is introduced into the heat exchanger (25) for cooling. The temperature sensor (29) detects the temperature of the smoke entering the heat exchanger (25). If the smoke temperature is greater than a preset value, the flow rate control component slows down the speed at which the smoke passes through the heat exchanger (25). Otherwise, the smoke is discharged from the heat exchanger (25) normally. S3: The temperature sensor (29) detects the temperature of the flue gas discharged from the heat exchanger (25). If the flue gas temperature is greater than a preset value, the controller (4) controls the condenser (26) to operate to perform secondary cooling on the flue gas. Otherwise, the condenser (26) does not cool the flue gas. S4: The flue gas passing through the condenser (26) enters the mixer (27) and is mixed with the air input by the fan (1) before entering the combustion tube (22).

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