A partial premix burner with explosion-proof and low nitrogen oxide

Abstract

This invention belongs to the field of burner technology and discloses an explosion-proof, low-NOx partially premixed burner, comprising a first air chamber, a first mixing chamber, a cooling water chamber, a second mixing chamber, and a second air chamber formed sequentially from the outside to the inside. Each air chamber is connected to an adjacent mixing chamber via a ventilation structure. Each mixing chamber has a plurality of swirling blades uniformly arranged circumferentially, located between the port of the partially premixed burner and the ventilation structure. During use, the static pressure of the gas in each mixing chamber is lower than the static pressure of the air in the adjacent air chamber. The excess air coefficient of the first premixed gas in the first mixing chamber is higher than the excess air coefficient of the second premixed gas in the second mixing chamber. This invention achieves partial premixing of fuel gas and air before the output port, making it difficult for the flame propagation speed to be lower than the airflow speed, thus reducing the risk of flameout; simultaneously, it forms a staged combustion and oxygen-deficient combustion state, achieving a low-NOx effect.

Description

Technical Field

[0001] This invention belongs to the field of burner technology, specifically relating to an explosion-proof, low-NOx partially premixed burner. Background Technology

[0002] Gas burners produce pollutants such as nitrogen oxides during combustion, contributing to severe environmental pollution. Therefore, there is a need to develop clean combustion technologies such as lean premixed combustion, dilute-phase premixed preevaporation, and lean direct injection. The stability and reliability of the burner are also crucial, requiring explosion-proof and flameout-proof operation. Partially premixed combustion, compared to fully premixed combustion, requires air diffusion during combustion, has a lower ignition point, slower flame propagation speed, and offers higher safety. It also significantly reduces thermal NOx emissions. X The formation of NO; ​​at the same time, compared with non-premixed flames, partially premixed flames can achieve complete combustion with a lower excess air coefficient; the combustion temperature is uniform, without localized high temperatures, the flame peak temperature is low, and the flame propagation speed is faster, resulting in a relatively short residence time of flue gas in the high-temperature region, and the NO generated during the combustion process is reduced. x Emissions are reduced, so these types of burners can achieve low-NOx performance.

[0003] However, the premixed combustion technology of burners in the present technology has certain defects. For example, the burner end temperature of some premixed burners is relatively low. When the gas supply rate is unstable, the reliability of the burner is still insufficient, and problems such as flameout or backfire explosion may occur. Summary of the Invention

[0004] The purpose of this invention is to provide an explosion-proof, low-NOx partially premixed burner to solve the technical problems of flameout or backfire explosion caused by the low temperature and insufficient combustion stability of the partially premixed burner in the prior art.

[0005] The explosion-proof, low-NOx partially premixed burner includes a first tube, a second tube, a third tube, a fourth tube, and a fifth tube arranged nested from the outside in. A first air chamber is located between the first and second tubes; a first mixing chamber is located between the second and third tubes; a cooling water chamber is located between the third and fourth tubes for introducing cooling water; a second mixing chamber is located between the fourth and fifth tubes; and the inner cavity of the fifth tube is a second air chamber. Both the first and second air chambers are for introducing air, and both the first and second mixing chambers are for introducing fuel gas and air for mixing. Each air chamber is connected to an adjacent mixing chamber via a ventilation structure. Several swirling blades are uniformly arranged circumferentially in each mixing chamber. These swirling blades are located between the port of the partially premixed burner and the ventilation structure. During use, the static pressure of the gas in each mixing chamber is lower than the static pressure of the air in the adjacent air chamber. The excess air coefficient of the first premixed gas in the first mixing chamber is higher than the excess air coefficient of the second premixed gas in the second mixing chamber.

[0006] Preferably, the ventilation structure includes a duct for connecting the air chamber and the adjacent mixing chamber, and the extension direction of each duct is consistent with the rotational flow direction of the premixed gas in the corresponding mixing chamber after the action of the swirl blades; the duct located inside the second tube body is the first duct, and the duct located outside the fifth tube body is the second duct; the first duct extends inward at an incline, and the second duct extends outward at an incline.

[0007] Preferably, the gas pipes are evenly distributed around the circumference to form a layer of gas pipes, and multiple layers of gas pipes are evenly arranged sequentially along the axial direction of the partial premixed burner. The ventilation capacity of the ventilation structure formed by the first gas pipe is greater than the ventilation capacity of the ventilation structure formed by the second gas pipe.

[0008] Preferably, the amount of gas introduced into the first mixing chamber and the second mixing chamber per unit time is the same, and the cross-sectional areas of the first mixing chamber and the second mixing chamber are the same; the excess air coefficient of the second premixed gas is between 0.2 and 0.5, while the excess air coefficient of the first premixed gas is between 1 and 3 times that of the second premixed gas.

[0009] Preferably, the swirl blades are all connected to the sidewall of the cooling water chamber. The swirl blades include a first swirl blade and a second swirl blade. The first swirl blade and the second swirl blade are respectively fixed in the first mixing chamber and the second mixing chamber. The swirl blades extend from the burner port into part of the premixed burner. The length of the swirl blade is not less than 20 times the radial thickness of the corresponding mixing chamber.

[0010] Preferably, a flame stabilizer is provided at the port of the partially premixed burner. The flame stabilizer includes a flame stabilizing pipe covering the port, an upper manifold located above the port, and a lower manifold located below the port. The upper manifold and the lower manifold are connected by the flame stabilizing pipe, and the upper manifold and the lower manifold form a tube-and-shell structure that wraps around the outside of the end.

[0011] Preferably, there are several flame stabilizing tubes arranged in parallel, and the sides of the flame stabilizing tubes are provided with tube fins; the tube fins are perpendicular to the flame stabilizing tubes, and the flame stabilizing tubes and the tube fins are connected to form a grid structure, and the grid structure is only provided in the area of ​​the port corresponding to the first mixing chamber and the second mixing chamber.

[0012] Preferably, the upper header is provided with a water inlet on the outer side away from the port position, and the lower header is provided with a drain outlet on the outer side of the port position.

[0013] This invention has the following advantages: In this design, air in the air chamber automatically enters the mixing chamber under the action of pressure difference, achieving mixing with the fuel. The outermost layer of the gas ejected from the port is air, while the premixed gas with a higher excess air coefficient ejected from the first mixing chamber surrounds the premixed gas with a lower excess air coefficient ejected from the second mixing chamber. The innermost layer is air ejected from the second air chamber. This structure ensures a more stable and continuous flame. Since the fuel and oxidizer are already mixed at the port, the flame propagation speed is appropriately increased, making it difficult for the flame propagation speed to fall below the airflow speed, thus reducing the risk of flameout. Simultaneously, because the premixed gases in the inner and outer mixing chambers use different concentrations, staged combustion is achieved, preventing the fuel and oxidizer from mixing completely too early. In the early stages of combustion, an oxygen-deficient combustion state is desired to achieve a low-NOx effect.

[0014] This solution employs partially premixed burner technology. Compared to non-premixed flames, partially premixed flames exhibit spatial combustion within the hydrogen fluid, rather than the non-premixed flame, where combustion occurs only at the hydrogen-air interface. This partial premixing results in an oxygen-deficient state within the hydrogen flow field in the main combustion zone, producing various reducing combustion products such as CH radicals. When the partially premixed hydrogen comes into contact with diffused air, the combustion stage enters the re-ignition zone. In the re-ignition zone, due to sufficient oxygen, the combustion temperature increases to a certain extent, reducing NO... x A large amount of these free radicals will be generated during this stage, when the reducing CH radicals in the main combustion zone react with NO. x Contact will bring NO x Reduced to N2, thus significantly reducing NO x Emissions.

[0015] In this design, the swirl vanes create a swirling flow in the premixed gas, increasing the mixing ratio of hydrogen and air at the burner outlet and also providing explosion protection. Furthermore, they act as fins on the cooling water chamber, transferring heat and ensuring effective cooling to prevent overheating and potential explosion. The arrangement of the gas pipes ensures that the deflection direction of the swirl is consistent with the deflection direction of the air input into the corresponding mixing chamber. This ensures that the air-driven premixed gas deflection direction aligns with the swirl deflection direction under the action of the swirl vanes, preventing obstruction of premixed gas flow at the front and rear.

[0016] At the burner outlet section, on the one hand, the temperature of fuel and oxidizer is reduced by water cooling and the flame stabilizing tube at the port. On the other hand, the grid structure is used as a blunt body to create gas turbulence and reduce the flow area to increase the gas velocity, further ensuring that the premixed gas velocity is greater than the flame propagation speed and improving flame stability. Therefore, this solution prevents backfire from the above two aspects and has a good explosion-proof effect. Attached Figure Description

[0017] Figure 1 This is a longitudinal sectional view of a partially premixed burner for explosion protection and low nitrogen oxides according to the present invention.

[0018] Figure 2 This is a cross-sectional view of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of the flame stabilizer in this invention.

[0020] Figure 4 This is a schematic diagram of the trachea installation structure in this invention.

[0021] The reference numerals in the attached drawings include: 1, first tube body; 2, second tube body; 3, third tube body; 4, fourth tube body; 5, fifth tube body; 6, flame stabilizer; 7, upper header; 8, lower header; 9, water collection tank; 10, first swirl vane; 11, second swirl vane; 12, cooling water chamber; 13, first air pipe; 14, second air pipe; 15, first air chamber; 16, first mixing chamber; 17, second mixing chamber; 18, second air chamber; 19, flame stabilizer tube; 20, tube fins. Detailed Implementation

[0022] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0023] like Figures 1-4As shown, this invention provides an explosion-proof, low-NOx partially premixed burner, comprising a first tube 1, a second tube 2, a third tube 3, a fourth tube 4, and a fifth tube 5 nested sequentially from the outside in. A first air cavity 15 is located between the first tube 1 and the second tube 2; a first mixing cavity 16 is located between the second tube 2 and the third tube 3; a cooling water cavity 12 for introducing cooling water is located between the third tube 3 and the fourth tube 4; a second mixing cavity 17 is located between the fourth tube 4 and the fifth tube 5; and the inner cavity of the fifth tube 5 is a second air cavity 18. Both the first air cavity 15 and the second air cavity 18 belong to... The air chambers for introducing air, the first mixing chamber 16 and the second mixing chamber 17 are both mixing chambers for introducing gas and air to mix. Each air chamber is connected to the adjacent mixing chamber through a ventilation structure. Each mixing chamber has a number of swirling blades evenly arranged in the circumference. The swirling blades are located between the port of the partial premixed burner and the ventilation structure. In use, the static pressure of the gas in each mixing chamber is less than the static pressure of the air in the adjacent air chamber. The excess air coefficient of the first premixed gas in the first mixing chamber 16 is higher than the excess air coefficient of the second premixed gas in the second mixing chamber 17.

[0024] The ventilation structure includes air pipes for connecting the air chamber and the adjacent mixing chamber, all of which are straight pipes; the first air pipe 13 is located inside the second pipe body 2, and the second air pipe 14 is located outside the fifth pipe body 5; the first air pipe 13 extends inward at an incline, and the second air pipe 14 extends outward at an incline. The extension direction of the first air pipe 13 is consistent with the rotational flow direction of the first premixed gas after the action of the swirl vanes, and the extension direction of the second air pipe 14 is consistent with the rotational flow direction of the second premixed gas after the action of the swirl vanes.

[0025] By designing the air pipes within the ventilation structure, air entering the mixing chamber is directed to rotate the premixed gas, enhancing its swirling effect. To ensure this swirling effect, the spatial angle between the first air pipe 13 and the second air pipe 14 and the axis of the premixed burner should not be too large. If the spatial angle is too large and inconsistent with the rotational flow direction of the premixed gas, the premixed gas output from the ventilation structure will rotate at a different angle under the action of the swirl vanes than the premixed gas driven by the air input. This obstruction of the gas's rotational flow will result in a loss of axial velocity in the premixed gas delivery.

[0026] The arrangement of the first gas pipe 13 and the second gas pipe 14 is as follows: A single layer of gas pipes is evenly distributed around the circumference, and multiple layers of gas pipes are evenly arranged sequentially along the axial direction of the partial premixed burner. The number of straight pipe layers and the number of straight pipes in each layer of the ventilation structure depend on the amount of air that needs to be mixed into the corresponding premixed gas per unit time. The amount of air that needs to be mixed into the corresponding premixed gas is determined by the excess air coefficient that the corresponding premixed gas needs to meet. For example, when hydrogen is used as the fuel gas, the excess air coefficient of the second premixed gas is between 0.2 and 0.5, while the excess air coefficient of the first premixed gas is between 1 and 3 times that of the second premixed gas. For example, in this embodiment, the excess air coefficient of the second premixed gas is 0.2, while the excess air coefficient of the first premixed gas is 0.4.

[0027] There are several ways to achieve the above-mentioned air coefficient relationship in the ventilation structure. One method is to have the nozzle cross-sectional area of ​​the first air pipe 13 be twice that of the second air pipe 14. The first air pipe 13 and the second air pipe 14 have the same number of layers and the same number of pipes per layer. The specific number, number of layers, and nozzle cross-sectional area are all determined by the amount of air to be mixed in. Another method is to have the nozzle cross-sectional area of ​​the second air pipe 14 equal to that of the first air pipe 13. The difference in ventilation volume is achieved by increasing the number of first air pipes 13, i.e., increasing the number of layers or the number of pipes per layer.

[0028] While determining the amount of air mixed in through the ventilation structure, to ensure stability, the amount of fuel gas introduced into the first mixing chamber 16 and the second mixing chamber 17 per unit time is the same. The first mixing chamber 16 and the second mixing chamber 17 have the same cross-sectional area, satisfying the following formula:

[0029]

[0030] Wherein, S1 is the cross-sectional area of ​​the first mixing chamber (16), S2 is the cross-sectional area of ​​the second mixing chamber (17), R1 is the outer diameter of the first mixing chamber (16), r1 is the inner diameter of the first mixing chamber (16), R2 is the outer diameter of the second mixing chamber (17), and r2 is the inner diameter of the second mixing chamber (17). This ensures that the mixing effect and excess air coefficient of different premixed gases meet the requirements.

[0031] The swirl vanes include a first swirl vane 10 and a second swirl vane 11, which are fixed within a first mixing chamber 16 and a second mixing chamber 17, respectively. Each swirl vane extends from the burner port into part of the premixed burner. The length of each swirl vane is not less than 20 times the radial thickness of the corresponding mixing chamber, i.e., L ≥ 20d, where L is the length of the swirl vane and d is the radial thickness of the corresponding mixing chamber. Each first swirl vane 10 extends axially while simultaneously deflecting in the same circumferential direction, and each second swirl vane 11 extends axially while also deflecting in the same circumferential direction. The swirl blades serve two functions: 1. They create a swirl in the premixed gas formed by hydrogen and air, increasing the mixing degree of hydrogen and air at the burner outlet. This swirl also stabilizes combustion, prevents backfire, and provides explosion protection. 2. All the swirl blades are connected to the sidewall of the cooling water chamber 12, thus acting as fins on the chamber and improving its heat transfer efficiency. The length of the swirl blades is at least 20 times the radial thickness of the corresponding mixing chamber to ensure a sufficiently large heat transfer area for optimal cooling. In this design, hydrogen flows under pressure and is premixed with air before being output through the swirl blades. The cooling water lowers the temperature of the premixed gas, preventing overheating and potential explosion.

[0032] A flame stabilizer 6 is provided at the port of the premixed burner. The flame stabilizer 6 includes a flame stabilizing tube 19 covering the port, an upper manifold 7 located above the port, and a lower manifold 8 located below the port. The upper manifold 7 and the lower manifold 8 are connected by the flame stabilizing tube 19, forming a tube-shell structure that wraps around the outer side of the end. There are several flame stabilizing tubes 19 arranged in parallel, and tube fins 20 are provided on the side of the flame stabilizing tube 19. The tube fins 20 are perpendicular to the flame stabilizing tube 19, and the flame stabilizing tube 19 and the tube fins 20 are connected to form a grid structure. The grid structure is only provided in the area of ​​the port corresponding to the first mixing chamber 16 and the second mixing chamber 17. The upper manifold 7 has a water inlet on its outer side away from the port, and the lower manifold 8 has a drain outlet on its outer side located at the port. Cold water enters the upper manifold 7 and then flows into the lower manifold 8 through the flame stabilization pipe 19. After heat exchange, the cold water is heated and discharged from the drain outlet of the lower manifold 8. The partially premixed burner is also equipped with a water collection tank 9, which is connected to the cooling water chamber 12. The water collection tank 9 is used to store cooling water and supply cooling water to the cooling water chamber 12.

[0033] In this design, the upper header 7 and lower header 8, which enclose the burner port, serve to cool the burner's combustion end face. The mesh structure has multiple small holes. When the premixed gas passes through, on the one hand, the mesh structure acts as a blunt body, causing the premixed gas to flow around the surface of the flame stabilizing tube 19 and the tube fins 20, creating a flow effect with a recirculation region. There is a transition zone with a large velocity gradient between the recirculation and the incoming flow, thus creating a flame stabilization zone that matches the flame propagation speed. This improves combustion stability, prevents backfire, and has an explosion-proof effect. On the other hand, the mesh structure reduces the flow area of ​​the premixed gas, increasing the premixed gas velocity and further ensuring that the premixed gas velocity is greater than the flame propagation speed, preventing backfire and also having an explosion-proof effect.

[0034] The working process of this embodiment is as follows: Sufficient air is introduced into each air chamber, and hydrogen as fuel gas is introduced into each mixing chamber. Cold water is also introduced into the cooling water layer and the flame stabilizer 6. The amount of hydrogen introduced into the first mixing chamber 16 and the second mixing chamber 17 is the same. Since the static pressure of hydrogen in the mixing chamber is relatively small, while the static pressure of air in the adjacent air chamber is relatively large, there is a pressure difference between the gas in each mixing chamber and the air in the adjacent air chamber. The air is then injected into the corresponding mixing chamber through the ventilation structure, so that the fuel gas and air are premixed in the mixing chamber. Since the ventilation volume of all first gas pipes 13 in this embodiment is twice the ventilation volume of all second gas pipes 14, the excess air coefficient of the second premixed gas after mixing is 0.2, while the excess air coefficient of the first premixed gas is 0.4.

[0035] The premixed gas flows towards the port through the swirl vanes. Under the action of the swirl vanes, the premixed gas forms a swirling flow, which improves the mixing degree of hydrogen and air at the burner outlet. Furthermore, the swirling flow of the premixed gas stabilizes combustion and prevents backfire. The deflection direction of this swirling flow is consistent with the deflection direction of the air input through the corresponding gas pipe in the mixing chamber. This ensures that the deflection direction of the air-driven premixed gas is consistent with the deflection direction of the swirling flow under the action of the swirl vanes, preventing obstruction of the premixed gas flow at the front and rear.

[0036] The premixed gas is finally ejected from the port to participate in combustion. Here, the premixed gas is ejected through the corresponding grid structure on the burner stabilizer 6, forming a flow around the surface of the cooling water pipe and the cooling water pipe fins 20. This creates a flame stabilization zone that matches the flame propagation speed, thereby achieving combustion stability and preventing backfire. At the same time, the port opening and the outside of the burner are cooled by the flame stabilization pipe 19, the upper header 7 and the lower header 8 on the burner stabilizer 6, preventing the port from overheating and causing an explosion.

[0037] Flameout typically occurs when the flame propagation speed is lower than the airflow speed. In conventional burners, the large concentration gradient between fuel and oxidizer at the port leads to poor mixing and slow flame propagation. When the airflow speed increases, the flame propagation speed can easily fall below the airflow speed. In this design, the outermost layer of the gas ejected from the port is air. The premixed gas with a high excess air coefficient ejected from the first mixing chamber 16 surrounds the premixed gas with a lower excess air coefficient ejected from the second mixing chamber 17. The innermost layer is air ejected from the second air chamber 18. This structure provides a more stable and continuous flame. The fuel and oxidizer are already mixed at the port, and the flame propagation speed is appropriately increased, making it difficult for the flame propagation speed to fall below the airflow speed, thus reducing the likelihood of flameout. Furthermore, because the premixed gases in the inner and outer mixing chambers use different concentrations, staged combustion is achieved, preventing premature and insufficient mixing of fuel and oxidizer. In the early stages of combustion, an oxygen-deficient combustion state is desired to achieve a low-NOx effect.

[0038] In the early stages of combustion, oxygen deficiency leads to the formation of reducing combustion products; the flame location corresponding to this process is called the main combustion zone. The re-combustion zone, on the other hand, refers to the combustion process after thorough mixing, and is also the corresponding flame location. In this design, the premixed gases from both the inner and outer sides create a staged combustion effect, resulting in a more uniform flame temperature in both the main and re-combustion zones, with fewer localized high-temperature points, thus reducing the flame temperature and achieving lower NO₂ levels. x The generated effect.

[0039] The burner employs a coaxial four-layer fuel and air supply configuration, achieving fuel and air grading through internal and external two-stage partial premixing and internal and external two-stage fuel supply. It also utilizes the aforementioned oxygen-deficient atmosphere creation mechanism, expanding the main combustion zone through two-stage premixing and two-stage air diffusion. Under high-load operation, the hydrogen flow rate is relatively high, and the grid structure of the burner 6 creates a recirculation zone within the hydrogen flow field, where the hydrogen flow rate is slower, thus stabilizing combustion. Simultaneously, the swirl blades in contact with the cooling water in the cooling water chamber 12 also cool the premixed gas near the port during combustion, preventing excessive temperature rise and potential explosion of the premixed gas within the burner.

[0040] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A partially premixed burner with explosion-proof low nitrogen oxides, characterized in that: The system comprises a first tube (1), a second tube (2), a third tube (3), a fourth tube (4), and a fifth tube (5) arranged in a nested manner from the outside in. The first tube (1) and the second tube (2) form a first air cavity (15). The second tube (2) and the third tube (3) form a first mixing cavity (16). The third tube (3) and the fourth tube (4) form a cooling water cavity (12) for introducing cooling water. The fourth tube (4) and the fifth tube (5) form a second mixing cavity (17). The inner cavity of the fifth tube (5) is a second air cavity (18). The first air cavity (15) and the second air cavity (18) are nested together. All of them belong to the air chambers for introducing air. The first mixing chamber (16) and the second mixing chamber (17) belong to the mixing chambers for introducing gas and air. Each air chamber is connected to the adjacent mixing chamber through a ventilation structure. Each mixing chamber is uniformly provided with several swirl blades in the circumferential direction. The swirl blades are located between the port of the partial premixed burner and the ventilation structure. In use, the static pressure of the gas in each mixing chamber is less than the static pressure of the air in the adjacent air chamber. The excess air coefficient of the first premixed gas in the first mixing chamber (16) is higher than the excess air coefficient of the second premixed gas in the second mixing chamber (17). A flame stabilizer (6) is provided at the port of the premixed burner. The flame stabilizer (6) includes a flame stabilizing pipe (19) covering the port, an upper manifold (7) located above the port, and a lower manifold (8) located below the port. The upper manifold (7) and the lower manifold (8) are connected by the flame stabilizing pipe (19). The upper manifold (7) and the lower manifold (8) form a pipe-casing structure that wraps around the outside of the port. The flame stabilizing tubes (19) are a plurality of tubes arranged in parallel, and the flame stabilizing tubes (19) are provided with tube fins (20) on their sides; the tube fins (20) are perpendicular to the flame stabilizing tubes (19), and the flame stabilizing tubes (19) and the tube fins (20) are connected to form a grid structure, and the grid structure is only provided in the area of ​​the port corresponding to the first mixing chamber (16) and the second mixing chamber (17).

2. The explosion-proof, low-NOx partially premixed burner according to claim 1, characterized in that: The ventilation structure includes a duct for connecting the air chamber and the adjacent mixing chamber. The extension direction of each duct is consistent with the rotational flow direction of the premixed gas in the corresponding mixing chamber after the action of the swirl blades. The duct located inside the second tube body (2) is the first duct (13), and the duct located outside the fifth tube body (5) is the second duct (14). The first duct (13) extends inward at an incline, and the second duct (14) extends outward at an incline.

3. The explosion-proof, low-NOx partially premixed burner according to claim 2, characterized in that: The gas pipes are evenly distributed around the circumference to form a layer of gas pipes. Multiple layers of gas pipes are evenly arranged along the axial direction of the partial premixed burner. The ventilation capacity of the ventilation structure formed by the first gas pipe (13) is greater than that of the ventilation structure formed by the second gas pipe (14).

4. The explosion-proof, low-NOx partially premixed burner according to claim 1, characterized in that: The first mixing chamber (16) and the second mixing chamber (17) have the same amount of gas introduced per unit time, and the first mixing chamber (16) and the second mixing chamber (17) have the same cross-sectional area; the excess air coefficient of the second premixed gas is between 0.2 and 0.5, while the excess air coefficient of the first premixed gas is between 1 and 3 times that of the second premixed gas.

5. The explosion-proof, low-NOx partially premixed burner according to claim 1, characterized in that: The swirl blades are all connected to the side wall of the cooling water chamber (12). The swirl blades include a first swirl blade (10) and a second swirl blade (11). The first swirl blade (10) and the second swirl blade (11) are respectively fixed in the first mixing chamber (16) and the second mixing chamber (17). The swirl blades extend from the burner port into part of the premixed burner. The length of the swirl blades is not less than 20 times the radial thickness of the corresponding mixing chamber.

6. The explosion-proof, low-NOx partially premixed burner according to claim 1, characterized in that: The upper header (7) has a water inlet on the outer side away from the port position, and the lower header (8) has a drain outlet on the outer side of the port position.

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