Low-nitrogen combustor based on flue gas circulation

Abstract

The utility model discloses a low nitrogen combustor based on flue gas circulation, including combustor casing, this combustor casing is from below and above in proper order is provided with first combustion chamber, second combustion chamber and third combustion chamber, first combustion chamber still install gas inlet pipe, ignition mouth and air inlet pipe on, the periphery of second combustion chamber still is provided with mixing chamber, the upper end of third combustion chamber still is provided with the smoke chamber of conical, the upper end of smoke chamber is installed and goes out the smoke outlet, the device adopts flue gas circulation technology, through the flue gas produced by a part of combustion is introduced into the combustion chamber again and mixes fresh air and then carries out the combustion, effectively inhibits the generation of NOx, simultaneously, the water vapor etc. in flue gas still can play the dilution and cooling effect, further reduces the discharge of NOx.

Description

Technical Field

[0001] This utility model relates to the field of heat exchange technology, specifically a low-NOx burner based on flue gas recirculation. Background Technology

[0002] In existing technologies, the main purpose of low-NOx burners is to reduce nitrogen oxide (NOx) emissions during fuel combustion. The primary technical means involves adjusting parameters such as the mixing method of combustion air and fuel, the oxygen concentration during combustion, and the flame temperature to suppress NOx formation. Specific methods in existing technologies include staged combustion, self-recirculating combustion, rich-lean combustion, segmented flame combustion, mixture-promoting combustion, and low-NOx pre-combustion chamber combustion. For example, staged burners mix fuel and air in stages, deviating from the stoichiometric ratio, thus reducing NOx formation. Self-recirculating burners utilize the combustion air head to draw back part of the combustion flue gas, mixing it with air for combustion, lowering the combustion temperature, and thus reducing NOx production. Therefore, they are widely used in industries such as power, heating, petrochemicals, food, and pharmaceuticals, meeting the requirements of different industries for combustion efficiency and NOx emissions.

[0003] The existing low-NOx burner structure, such as the "Low-NOx Burner" disclosed in Publication (Announcement) No.: CN206055619U, mainly achieves low-NOx combustion by setting a swirl impeller in the combustion chamber, generating a rotating airflow through the swirl impeller. The rotating airflow is annular and impacts multiple single-stream gas flow, so that the air and gas in the primary mixture reach the theoretical air-fuel ratio for complete combustion.

[0004] For example, the "Low-NOx Burner" disclosed in Publication (Announcement) No. CN217635614U has multiple peripheral nozzle assemblies, which can effectively reduce the generation of nitrogen oxides; the overall technical solution is also relatively reasonable.

[0005] However, existing technologies cannot achieve low-NOx combustion simply by setting up airflow and spray components. Existing technologies can use staged combustion and flue gas recirculation combustion to achieve low-NOx combustion, but these two methods are set up separately. For staged combustion, several combustion chambers are usually set up to achieve low NOx through staged combustion in multiple combustion chambers. Flue gas recirculation requires sending the combusted flue gas back into the combustion chamber for combustion. The two methods cannot be effectively combined, and the combustion effect is not as good as fresh air through flue gas recirculation combustion, resulting in poor combustion effect.

[0006] Therefore, in order to solve the above problems, it is necessary to develop a low-NOx burner based on flue gas recirculation with a reasonable structure and good combustion effect. Utility Model Content

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-NOx burner based on flue gas recirculation; the technical solution is as follows:

[0008] A low-NOx burner based on flue gas recirculation includes a burner housing, within which a first combustion chamber, a second combustion chamber, and a third combustion chamber are arranged sequentially from bottom to top. The first combustion chamber is also equipped with a gas inlet pipe, an ignition nozzle, and an air inlet pipe. A mixing chamber is also arranged around the second combustion chamber. A conical smoke outlet chamber is also provided at the upper end of the third combustion chamber, and a smoke outlet is installed at the upper end of the smoke outlet chamber.

[0009] The conical inner wall of the smoke outlet chamber is also provided with an upwardly protruding smoke collection hood, and the upper end of the smoke collection hood is also equipped with several smoke collection pipes, which are connected to the circulation pipes, and the circulation pipes are connected to the mixing chamber. The mixing chamber is also equipped with a makeup air pipe, and a connecting pipe is also installed between the mixing chamber and the second combustion chamber.

[0010] The flue gas in the third combustion chamber enters the mixing chamber through the flue gas collection pipe and the circulation pipe, and is mixed with the air entering the mixing chamber through the make-up air pipe, and then sent to the second combustion chamber through the connecting pipe.

[0011] Furthermore, a gas distribution mesh is installed at the end of the gas inlet pipe; the gas distribution mesh can make the gas entering from the gas inlet pipe evenly distributed, which facilitates ignition by the igniter.

[0012] Furthermore, fans are installed on both the circulation pipe and the make-up air pipe; the fans installed on the pipes can effectively introduce flue gas and air into the mixing chamber.

[0013] Furthermore, valve bodies are installed on both the circulation pipe and the connecting pipe; the valve bodies can close the circulation pipe and the connecting pipe, and open and close them as needed.

[0014] Furthermore, the vertical cross-section of the smoke hood is in the shape of an "eight", and the smoke collection pipes are all installed on the upper end of the smoke hood.

[0015] Furthermore, two smoke hoods are provided, symmetrically arranged on both sides of the conical inner wall of the smoke outlet chamber, and the smoke collection pipes are evenly spaced and installed on the smoke hoods; correspondingly, a mixing chamber is provided on each side of the second combustion chamber, and the mixing chamber is connected to the corresponding circulation pipe.

[0016] Furthermore, the upper side of the mixing chamber is connected to a circulation pipe, the outer end is connected to a makeup air pipe, and the inner end is connected to a connecting pipe that connects to the second combustion chamber. A vertical smoke filter screen is also installed on the inner side of the mixing chamber.

[0017] The flue gas entering through the circulation pipe mixes with the air entering through the make-up air pipe, and then passes through a dust filter before entering the second combustion chamber through the connecting pipe.

[0018] Furthermore, an inclined dust collection trough is provided at the bottom of the mixing chamber. The dust collection trough is located outside the dust filter screen. The dust particles filtered by the dust filter screen fall into the dust collection trough. A dust collection pipe is also installed on the dust collection trough, and a pump body is installed on the dust collection pipe.

[0019] Beneficial effects: This utility model has the following beneficial effects:

[0020] 1) This device is equipped with three combustion chambers. The staged combustion of the three combustion chambers can effectively suppress the formation of NOx. In the initial stage of combustion, the gas inlet pipe is used for fuel-rich combustion, and the air inlet pipe is used to supplement oxygen, thereby reducing the formation of NOx. Even if there is an excess of gas and insufficient oxygen, this can reduce the flame temperature, reduce the formation of thermal NOx, and reduce the emission of exhaust gas and pollutants.

[0021] 2) In the later stage of combustion, air is supplied through the air supply pipe on the mixing chamber of the second combustion chamber to complete the combustion of fuel, which significantly reduces NOx emissions and improves combustion efficiency.

[0022] 3) This device adopts flue gas recirculation technology, which effectively suppresses the formation of NOx by reintroducing a portion of the flue gas generated by combustion back into the combustion chamber to mix with fresh air before combustion. At the same time, water vapor and other substances in the flue gas can also play a role in dilution and cooling, further reducing NOx emissions.

[0023] 4) The design of the conical smoke outlet chamber and the smoke collection hood in this device is quite important. The conical inner wall allows the flue gas to flow upwards, and the smoke collection hood is set on the conical inner wall of the smoke outlet chamber, so that the flue gas can smoothly enter the smoke collection hood. The structure is reasonably designed.

[0024] 5) This device also features a mixing chamber structure, which can effectively trap soot particles in the flue gas and recover them accordingly, making the structure reasonable. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the present utility model;

[0026] Figure 2 for Figure 1 Sectional view of AA;

[0027] Figure 3 for Figure 1 BB section view;

[0028] Figure 4 for Figure 3 CC section view;

[0029] Figure 5 This is a structural diagram of the mixing chamber in this utility model;

[0030] The components include: burner housing 1, first combustion chamber 101, second combustion chamber 102, third combustion chamber 103, gas inlet pipe 2, igniter 3, air inlet pipe 4, mixing chamber 5, smoke outlet chamber 6, smoke outlet 7, smoke hood 8, smoke collection pipe 9, circulation pipe 10, make-up air pipe 11, connecting pipe 12, fan 13, valve body 14, dust filter screen 15, dust collection trough 16, dust collection pipe 17, and pump body 18. Detailed Implementation

[0031] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented under the premise of the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, a low-NOx burner based on flue gas recirculation includes a burner housing 1. Inside the burner housing 1, from bottom to top, are arranged a first combustion chamber 101, a second combustion chamber 102, and a third combustion chamber 103. The first combustion chamber 101 is also equipped with a gas inlet pipe 2, an ignition nozzle 3, and an air inlet pipe 4. A mixing chamber 5 is also arranged around the second combustion chamber 102. A conical smoke outlet chamber 6 is also provided at the upper end of the third combustion chamber 103, and a smoke outlet 7 is installed at the upper end of the smoke outlet chamber 6.

[0033] The conical inner wall of the smoke outlet chamber 6 is also provided with an upwardly protruding smoke collection hood 8, and the upper end of the smoke collection hood 8 is also provided with several smoke collection pipes 9, which are connected to the circulation pipe 10, and the circulation pipe 10 is connected to the mixing chamber 5. The mixing chamber 5 is also provided with a makeup air pipe 11, and a connecting pipe 12 is also provided between the mixing chamber 5 and the second combustion chamber 102.

[0034] The flue gas in the third combustion chamber 103 enters the mixing chamber 5 through the smoke collection pipe 9 and the circulation pipe 10, and is mixed with the air that enters the mixing chamber 5 through the make-up air pipe 11. Then it is sent to the second combustion chamber 102 through the connecting pipe 12.

[0035] A gas distribution screen 201 is also installed at the end of the gas inlet pipe 2; a fan 13 is installed on both the circulation pipe 10 and the make-up air pipe 11; and a valve body 14 is installed on both the circulation pipe 10 and the connecting pipe 12.

[0036] like Figure 4As shown, the vertical cross-section of the smoke hood 8 is shaped like the number "8", and the smoke collection pipes 9 are all installed on the upper end of the smoke hood 8.

[0037] Two smoke hoods 8 are provided, symmetrically arranged on both sides of the conical inner wall of the smoke outlet chamber 6. Smoke collection pipes 9 are evenly spaced and installed on the smoke hoods 8. Correspondingly, a mixing chamber 5 is provided on each side of the second combustion chamber 102, and the mixing chamber 5 is connected to the corresponding circulation pipe 10.

[0038] The upper side of the mixing chamber 5 is connected to the circulation pipe 10, the outer end is connected to the make-up air pipe 11, and the inner end is connected to the second combustion chamber 102 by a corresponding connecting pipe. A vertical smoke filter 15 is also installed on the inner part of the mixing chamber 5.

[0039] The flue gas entering through the circulation pipe 10 mixes with the air entering through the make-up air pipe 11, and then passes through the dust filter 15 before entering the second combustion chamber 102 through the connecting pipe 12.

[0040] like Figure 4 As shown, an inclined dust collection trough 16 is also provided at the bottom of the mixing chamber 5. The dust collection trough 16 is located outside the dust filter screen 15. The dust particles filtered by the dust filter screen 15 fall into the dust collection trough 16. A dust collection pipe 17 is also installed on the dust collection trough 16, and a pump body 18 is installed on the dust collection pipe 17.

[0041] The first combustion chamber 101 of this device is equipped with a gas inlet pipe 2, an air inlet pipe 4, and an ignition nozzle 3. Therefore, the ignition of the entire device takes place within the first combustion chamber 101. The corresponding gases enter through the gas inlet pipe 2 and the air inlet pipe 4, and are then ignited by the ignition nozzle 3 to form combustion. The second combustion chamber 102 serves as a transition zone and a subsequent flue gas recirculation chamber. The actual combustion process is completed in the third combustion chamber 103. The space of the third combustion chamber 103 is significantly larger than that of the second combustion chamber 102 and the first combustion chamber 101. The third combustion chamber 103 generates a filling gas... The combustion process involves three stages: combustion chambers, combustion stage, and combustion stage. The resulting flue gas enters the conical smoke chamber 6 and is then discharged through the smoke outlet 7 on the combustion chamber. This staged combustion effectively suppresses NOx formation. In the initial stage of combustion, the fuel gas inlet pipe 2 is used for fuel-rich combustion, and oxygen is supplemented through the air inlet pipe 4 to reduce NOx formation. Even if there is an excess of fuel gas and insufficient oxygen, this can lower the flame temperature and reduce the formation of thermal NOx. Subsequently, in the later stage of combustion, air is supplemented through the external air supply pipe 11 to complete the combustion of the fuel, significantly reducing NOx emissions and improving combustion efficiency.

[0042] The technical solution of this device also includes flue gas circulation. Firstly, the inner wall of the smoke outlet chamber 6 is designed as a conical structure. Then, a smoke collection hood 8 is installed on the conical inner wall. When the flue gas flows upward, it moves upward along the conical inner wall, naturally entering the smoke collection hood 8. A smoke collection pipe 9 is installed on the smoke collection hood 8, which connects to a circulation pipe 10. A fan 13 is also installed on the circulation pipe 10. Under the combined action of the fan 13 and the smoke collection hood 8, a portion of the flue gas enters the smoke collection hood 8 and subsequently the circulating gas. The flue gas enters the flue gas duct 9, then the circulation duct 10, and finally the mixing chamber 5. The mixing chamber 5 of this device not only receives the flue gas but also has a makeup air duct 11, through which external air enters. The air mixes with the flue gas in the mixing chamber 5 before entering the second combustion chamber 102 for combustion. This effectively reduces the flame temperature and replenishes oxygen, achieving complete combustion and inhibiting NOx formation. At the same time, the water vapor in the flue gas and the replenished air also plays a role in dilution and cooling, further reducing NOx emissions.

[0043] The design of the conical smoke outlet chamber 6 and the smoke collection hood 8 in this device is quite important. In the prior art, the smoke outlet chamber 6 is mostly set in the form of a funnel to increase the smoke discharge efficiency. However, since part of the smoke in this device needs to be recycled, the smoke outlet chamber 6 is set in a conical shape. The inner wall of the cone allows the smoke to flow upwards. The smoke collection hood 8 is set on the inner wall of the conical smoke outlet chamber 6, so that the smoke can smoothly enter the smoke collection hood 8. The structural design is very reasonable and ingenious.

[0044] In addition, the technical solution of this device also includes a specific design for the structure of the mixing chamber 5. Since the flue gas circulating into the chamber contains a large amount of soot particles, if these particles then enter the combustion chamber, they will significantly affect the combustion effect. Therefore, it is necessary to remove these soot particles. In this device, a flue gas circulation pipe 10 is installed at the upper end of the mixing chamber 5, a make-up air pipe 11 is installed on the outer side, and a connecting pipe 12 is installed on the inner side, corresponding to the second combustion chamber 102. Most importantly, a vertical soot filter 15 needs to be installed in the mixing chamber 5. The soot filter 15 is installed in the connecting pipe 12. At the front end of pipe 12, the air entering from the make-up air pipe 11 and the flue gas entering from the circulation pipe 10 are mixed. Then, a dust filter 15 is used to intercept dust particles in the mixed gas. The dust filter 15 in this device is not designed to intercept all dust particles, nor is it possible to do so. The dust particle filter of this device is only designed to intercept large dust particles. The intercepted dust particles fall into the dust collection tank 16 and are then drawn away by the dust collection pipe 17 installed on the dust collection tank 16 through the pump body 18, which can effectively complete the dust particle recycling and cleaning work.

[0045] The above-described specific embodiments are merely preferred embodiments of this utility model and are not intended to limit the implementation of this utility model or the scope of the claims. All equivalent changes and modifications made in accordance with the scope of protection of this utility model patent application should be included within the scope of this utility model patent application.

Claims

1. A low-NOx burner based on flue gas recirculation, characterized in that: The device includes a burner housing (1), which contains a first combustion chamber (101), a second combustion chamber (102), and a third combustion chamber (103) arranged sequentially from bottom to top. The first combustion chamber (101) is also equipped with a gas inlet pipe (2), an ignition nozzle (3), and an air inlet pipe (4). A mixing chamber (5) is also arranged around the second combustion chamber (102). A conical smoke outlet chamber (6) is also arranged at the upper end of the third combustion chamber (103), and a smoke outlet (7) is installed at the upper end of the smoke outlet chamber (6). The conical inner wall of the smoke outlet chamber (6) is also provided with an upwardly protruding smoke collection hood (8), and the upper end of the smoke collection hood (8) is also provided with several smoke collection pipes (9), the smoke collection pipes (9) are connected to the circulation pipe (10), the circulation pipe (10) is connected to the mixing chamber (5), the mixing chamber (5) is also provided with a makeup air pipe (11), and a connecting pipe (12) is also provided between the mixing chamber (5) and the second combustion chamber (102). The flue gas in the third combustion chamber (103) enters the mixing chamber (5) through the smoke collection pipe (9) and the circulation pipe (10), and is mixed with the air that enters the mixing chamber (5) through the make-up air pipe (11), and then sent to the second combustion chamber (102) through the connecting pipe (12).

2. A low-NOx burner based on flue gas recirculation according to claim 1, characterized in that: The gas inlet pipe (2) is also equipped with a gas equalization mesh cover (201) at its end.

3. A low-NOx burner based on flue gas recirculation according to claim 1, characterized in that: A fan (13) is installed on both the circulation pipe (10) and the air supply pipe (11).

4. A low-NOx burner based on flue gas recirculation according to claim 1, characterized in that: Valve bodies (14) are installed on both the circulation pipe (10) and the connecting pipe (12).

5. A low-NOx burner based on flue gas recirculation according to claim 1, characterized in that: The vertical cross-section of the smoke hood (8) is shaped like the number "8", and the smoke collection pipes (9) are all installed on the upper end of the smoke hood (8).

6. A low-NOx burner based on flue gas recirculation according to claim 5, characterized in that: There are two smoke collection hoods (8), which are symmetrically arranged on both sides of the conical inner wall of the smoke outlet chamber (6). The smoke collection pipes (9) are evenly spaced and installed on the smoke collection hoods (8). Correspondingly, a mixing chamber (5) is provided on each side of the second combustion chamber (102), and the mixing chamber (5) is connected to the circulation pipe (10) on the corresponding side.

7. A low-NOx burner based on flue gas recirculation according to claim 6, characterized in that: The upper side of the mixing chamber (5) is connected to the circulation pipe (10), the outer end is connected to the air supply pipe (11), and the inner end is connected to the second combustion chamber (102). A vertical smoke filter (15) is also installed on the inner side of the mixing chamber (5). The flue gas entering through the circulation pipe (10) is mixed with the air entering through the make-up air pipe (11), then filtered through the dust filter (15) and enters the second combustion chamber (102) through the connecting pipe (12).

8. A low-NOx burner based on flue gas recirculation according to claim 7, characterized in that: The bottom of the mixing chamber (5) is also provided with an inclined dust collection trough (16). The dust collection trough (16) is located outside the dust filter screen (15). The dust particles filtered by the dust filter screen (15) fall into the dust collection trough (16). A dust collection pipe (17) is also installed on the dust collection trough (16), and a pump body (18) is installed on the dust collection pipe (17).

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