Semi-premixed internal circulation low nitrogen burner

Abstract

The present invention provides a semi-premixed internal circulation low-nitrogen burner, comprising: a refractory castable annular platform, an air channel formed on the inner side of the refractory castable annular platform; an inner gas channel; an inner gas-air mixing channel; a middle gas channel; a middle gas ring; a middle gas nozzle; an outer gas channel; an outer gas ring; and an outer gas nozzle. The inner gas channel and the inner gas-air mixing channel are provided to premix the gas and air. Fine gas nozzles are provided on the middle gas ring and the outer gas ring, and the gas is ejected from the gas nozzles at high speed. The ejected high-speed gas has high kinetic energy and can entrain surrounding flue gas. Before the gas and air are mixed and burned, the area where the nozzles are located is not provided with combustion-supporting air. The gas decomposes into reducing substances such as CO and H+ in an oxygen-deficient environment, and the concentration of the gas is reduced to a certain extent, thereby reducing the calorific value of the fuel. As a result, when the gas and air are combined for combustion, the combustion peak temperature is low.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler and industrial furnace emission reduction, and in particular to a semi-premixed internal circulation low-nitrogen burner. Background Art

[0002] Nitrogen oxides, a highly harmful pollutant, are a major contributor to acid rain and smog. Currently, nitrogen reduction methods in industrial boilers can be broadly categorized into combustion-based nitrogen reduction and flue gas post-treatment. Combustion-based nitrogen reduction reduces nitrogen oxide production during the combustion process, while flue gas post-treatment reduces nitrogen oxide emissions by treating the flue gas after combustion. Compared to flue gas post-treatment, combustion-based nitrogen reduction offers advantages such as lower investment, virtually no additional operating costs, and zero secondary pollution.

[0003] Many provinces and cities across the country require natural gas boiler nitrogen oxide emissions to be as low as 30mg / Nm 3 . For relatively clean fuels with high calorific value such as natural gas, the nitrogen oxides generated during combustion are mostly thermal nitrogen oxides. Common and effective means of reducing nitrogen by burning such fuels include diffusion combustion combined with flue gas recirculation technology and fully premixed surface combustion technology. Existing flue gas recirculation technology often has condensation water problems during application, and the existing flue gas recirculation has more or less an impact on the thermal efficiency of the boiler, and the addition of external circulating flue gas is prone to cause boiler vibration problems due to uneven mixing; fully premixed surface combustion technology is to premix the fuel and combustion air before combustion. This technology has strict requirements on air distribution. Too much or too little oxygen will affect the stability of combustion and even cause safety accidents. Summary of the Invention

[0004] To achieve the above-mentioned and other related purposes, the present invention provides a semi-premixed internal circulation low-nitrogen burner, comprising: a refractory castable annular table, the refractory castable annular table comprising a first surface and a second surface opposite to each other, an air channel formed on the inner side of the refractory castable annular table, the air channel extending from the first surface to the second surface; an internal gas channel located in the air channel, extending from the first surface to the air channel; an internal gas-air mixing channel located in the air channel, one end of which is connected to the internal gas channel, and the other end of which extends to the downstream of the second surface; a middle-layer gas channel located in the refractory castable annular table, the middle-layer gas channel extending from the first surface to the downstream of the second surface the outer gas channel is located in the annular platform of the refractory castable, and the outer gas channel extends from the first surface to the second surface; the outer gas ring is located on the second surface, surrounds the outer gas ring, and is communicated with the outer gas channel, and has a one-to-one correspondence with the outer gas channel; the outer gas nozzles are located on the outer gas ring and are communicated with the outer gas ring; the outer gas channel is located in the annular platform of the refractory castable, and the outer gas channel extends from the first surface to the second surface; the outer gas ring is located on the second surface, surrounds the outer gas ring, and is communicated with the outer gas channel, and has a one-to-one correspondence with the outer gas channel; the outer gas nozzles are located on the outer gas ring and are communicated with the outer gas ring.

[0005] Optionally, there are multiple internal gas channels and multiple internal combustion air mixing channels, and the internal gas channels and the internal combustion air mixing channels are arranged in a one-to-one correspondence; the multiple internal gas channels and the multiple internal combustion air mixing channels are arranged at intervals with the center line of the semi-premixed internal circulation low-nitrogen burner as the axis.

[0006] Optionally, the internal gas channel is a tapered channel, and the flow area of ​​the end of the internal gas channel that is connected to the internal combustion air mixing channel is the smallest.

[0007] Optionally, the outlet of the internal combustion air mixing channel is a bent portion, which bends toward the refractory castable annular platform; the angle between the bent portion and the center line of the semi-premixed internal circulation low nitrogen burner is 30° to 90°.

[0008] Optionally, there are multiple middle-layer gas nozzles and multiple outer-layer gas nozzles, and the multiple middle-layer gas nozzles are arranged along the circumference of the middle-layer gas ring, and the multiple outer-layer gas nozzles are arranged along the circumference of the outer-layer gas ring.

[0009] Optionally, the angle between the injection direction of the outer layer gas nozzle and the center line of the semi-premixed internal circulation low nitrogen burner is -10° to 60°; the angle between the injection direction of the middle layer gas nozzle and the center line of the semi-premixed low nitrogen burner is 10° to 70°.

[0010] Optionally, the refractory castable annular platform includes a first layer of a refractory castable annular platform, a second layer of a refractory castable annular platform and a third layer of a refractory castable annular platform stacked in sequence from the outside to the inside; the outer layer gas channel and the middle layer gas channel are both located in the first layer of the refractory castable annular platform; the injection direction of the outer layer gas nozzle and the injection direction of the middle layer gas nozzle are both toward the second layer of the refractory castable annular platform.

[0011] Optionally, the second surface of the second layer of the refractory castable annular platform includes an inclined surface and a horizontal surface, the inclined surface extends from the first layer of the refractory castable annular platform to the horizontal surface of the second layer of the refractory castable annular platform; the inclination angle of the inclined surface is 30° to 60°; the second surface of the second layer of the refractory castable annular platform is provided with a first annular groove, and the second surface of the third layer of the refractory castable annular platform is provided with a second annular groove, the second annular groove surrounds the periphery of the air channel, and the first annular groove surrounds the periphery of the second annular groove.

[0012] Optionally, the inner wall of the refractory castable annular platform includes an inclined inner wall, so that the diameter of the opening of the air channel on the second surface is larger than the diameter of the opening on the first surface.

[0013] Optionally, a flame stabilizing disk is further included, which is located downstream of the air channel. The flame stabilizing disk is provided with swirl blades and through holes, the through holes are connected to the air channel, and the swirl blades are located outside the through holes; the internal gas-air mixing channel is located outside the flame stabilizing disk.

[0014] As described above, the semi-premixed internal circulation low nitrogen burner of the present invention has the following beneficial effects:

[0015] The arrangement of the internal gas channel and the internal gas-air mixing channel enables the gas and air to be premixed.

[0016] Fine gas nozzles are provided on the middle gas ring and the outer gas ring, and the gas is ejected from the gas nozzles at high speed. The ejected high-speed gas has high kinetic energy and can draw in the surrounding flue gas. Before the gas and air are mixed and burned, no combustion-supporting air is provided in the area where the nozzles are located. The gas is decomposed into reducing substances such as CO and H+ in an oxygen-deficient environment, and the concentration of the gas is reduced to a certain extent, thereby reducing the calorific value of the fuel. Therefore, when the gas and air are combined for combustion, the combustion peak temperature is low. The above method can effectively reduce the generation of nitrogen oxides.

[0017] Most of the gas is ejected from the middle and outer gas nozzles, and there is very little premixed gas in the center area of ​​the burner. This structure makes the flame hollow. The hollow flame means that there is no flame at the root and center of the entire flame. Therefore, it can effectively control the temperature of the combustion center area, thereby reducing the generation of thermal nitrogen oxides.

[0018] In this example, the internal gas channel is placed inside the air channel, and the rear end of the internal gas channel is connected to the internal gas-air mixing device. The rear end of the internal gas channel consists of a gradually tapering section and a straight section. Due to the Venturi effect at the constriction of the internal gas channel, the gas flow rate is high, forming a relatively negative pressure environment, making it easier for the air in the air channel to enter the internal gas-air mixing channel. Part of the gas and air are premixed and burned in the internal gas-air mixing channel. The premixed combustion temperature is more uniform, and the peak combustion temperature is lower, which can effectively reduce the formation of thermal nitrogen oxides. The premixing gun can also stabilize the main flame and provide a heat source for the outer fuel.

[0019] The middle layer gas nozzles and the outer layer gas nozzles respectively spray fuel into the combustion area at a certain angle. This structure avoids excessive concentration of the fuel injection area, effectively utilizes the combustion space, makes the combustion temperature more uniform, and reduces the generation of thermal nitrogen oxides.

[0020] The setting of multiple gas nozzles realizes multi-stage combustion, and the injection of multiple gas nozzles makes the fuel injection more uniform; and the injection of gas from multiple nozzles can also better mix the fuel and flue gas, reduce the calorific value of the fuel as much as possible, and effectively control the combustion speed, thereby reducing the generation of thermal nitrogen oxides.

[0021] The air channel is a flaring device. This structure allows air to diffuse into the combustion area, fully utilizing the combustion space, improving the furnace filling degree and making the combustion temperature more uniform.

[0022] A flame stabilization disk is placed downstream of the air channel. This creates negative pressure at its rear end, entraining high-temperature flue gas and achieving internal flue gas circulation. This internal flue gas circulation reduces the temperature and oxygen content in the combustion zone, thereby lowering the combustion peak and, in turn, reducing the formation of thermal nitrogen oxides. The flame stabilization disk is also equipped with swirl vanes, which increase the radial kinetic energy of the air and enhance mixing between air and gas.

[0023] The refractory castable ring is divided into three layers. The protruding refractory castables within these three layers store heat and stabilize combustion, enabling stable combustion at oxygen levels between 0% and 3%. Annular grooves in the second and third layers of the refractory castable ring effectively increase flue gas swirl, enhancing the mixing time and effectiveness of the fuel gas, thereby reducing the calorific value of the fuel gas and controlling the formation of thermal nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a top view of the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0025] Figure 2 The semi-premixed internal circulation low nitrogen burner provided by the present invention is along Figure 1 Cross-section view in the AA direction.

[0026] Figure 3 This is a gas flow diagram of the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0027] Figure 4 This is an enlarged schematic diagram of the middle-layer gas ring and the middle-layer gas nozzle in the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0028] Figure 5 This is a structural schematic diagram of the internal gas channel and the internal gas-air mixing channel in the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0029] Figure 6 This is an enlarged schematic diagram of the outer gas ring and outer gas nozzle in the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0030] Figure 7 This is a partial cross-sectional view of the castable annular platform in the semi-premixed internal circulation low-nitrogen burner provided by the present invention.

[0031] Component number explanation: 1. Refractory castable annular platform, 101. First layer of refractory castable annular platform, 102. Second layer of refractory castable annular platform, 1021. First annular groove, 103. Third layer of refractory castable annular platform, 1031. Second annular groove, 2. Outer gas ring, 3. Outer gas nozzle, 4. Middle gas ring, 5. Middle gas nozzle, 6. Inner gas channel, 7. Inner gas-air mixing channel, 8. Air channel, 9. Flame stabilizing disk, 10. Inner gas-air mixing channel wall, 11. Outer gas channel, 12. Middle gas channel. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The preferred embodiments described below are for illustrative purposes only, and those skilled in the art may readily conceive of other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0034] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "upstream", "downstream" and the like to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.

[0035] As mentioned above, current methods for reducing nitrogen oxides (NOx) in industrial boilers can be broadly categorized as combustion-based and flue gas post-treatment. Combustion-based NOx reduction involves reducing NOx production during the combustion process, while flue gas post-treatment involves treating the flue gas after combustion to reduce NOx emissions. Compared to flue gas post-treatment, combustion-based NOx reduction offers advantages such as lower investment, virtually no additional operating costs, and zero secondary pollution. For relatively clean fuels with high calorific value, such as natural gas, NOx generated during combustion are primarily thermal. Common and effective combustion-based NOx reduction methods for these fuels include diffusion combustion combined with flue gas recirculation (FGR) and fully premixed surface combustion (FPC). FGR often results in condensate during use, and FGR can impact boiler thermal efficiency to some extent. Furthermore, the addition of recirculated FGR can easily cause boiler vibration due to uneven mixing. Fully premixed surface combustion, in which fuel and combustion air are premixed prior to combustion, places stringent air distribution requirements on this technology. Excessive or insufficient oxygen can affect combustion stability and even lead to safety hazards.

[0036] Example 1

[0037] See also Figures 1 to 2As shown, the present invention provides a semi-premixed internal circulation low nitrogen burner, comprising: a refractory castable annular table 1, the refractory castable annular table 1 comprising a first surface and a second surface opposite to each other, the first surface being the front upstream surface, and the second surface being the rear downstream surface, an air channel 8 is formed on the inner side of the refractory castable annular table 1, the air channel 8 extending from the first surface to the second surface; an internal gas channel 6, located in the air channel 8, extending from the first surface to the air channel 8; an internal gas-air mixing channel 7, located in the air channel 8, one end of which is connected to the internal gas channel 6, and the other end of which extends to the downstream of the second surface; a middle-layer gas channel 12, located in the refractory castable annular table 1, the middle-layer gas channel 12 extending from the The first surface extends to the second surface; the middle gas ring 4 is located on the second surface, surrounds the periphery of the air channel 8, and is connected to the middle gas channel 12, and has a one-to-one correspondence with the middle gas channel 12; the middle gas nozzles 5 are located on the middle gas ring 4 and are connected to the middle gas ring 4; the outer gas channel 11 is located in the refractory castable annular platform 1, and the outer gas channel 11 extends from the first surface to the second surface; the outer gas ring 2 is located on the second surface, surrounds the periphery of the middle gas ring 4, and is connected to the outer gas channel 11, that is, has a one-to-one correspondence with the outer gas channel 11; the outer gas nozzles 3 are located on the outer gas ring 2 and are connected to the outer gas ring 2.

[0038] In the semi-premixed internal circulation low-nitrogen burner of the present application, the internal gas channel 6 and the internal gas-air mixing channel 7 are provided to premix the gas and air. Fine gas nozzles are provided on the middle gas ring 4 and the outer gas ring 2, and the gas is ejected from the gas nozzles at high speed. The ejected high-speed gas has high kinetic energy and can entrain the surrounding flue gas. Before the gas and air are mixed and burned, the area where the nozzles are located is not provided with combustion-supporting air. The gas decomposes into reducing substances such as CO and H+ in an oxygen-deficient environment, and the concentration of the gas is reduced to a certain extent, thereby reducing the calorific value of the fuel. Therefore, when the gas and air are combined for combustion, the combustion peak temperature is low, thereby reducing the generation of nitrogen oxides. Most of the gas is ejected from the middle and outer gas nozzles, and there is very little premixed gas in the center area of ​​the burner. This structure makes the flame hollow. The hollow flame means that no flame is generated at the root and center of the entire flame, so it can effectively control the temperature of the combustion center area, thereby reducing the generation of thermal nitrogen oxides. Without the need for external flue gas circulation, there will be no uneven mixing of flue gas and air, and no boiler vibration problems will occur; the traditional non-metallic mesh premixed combustion has no strict requirements on air distribution, and will not affect the stability of combustion due to excessive or insufficient oxygen, thereby avoiding safety accidents.

[0039] Example 2

[0040] Please combine Figure 1 See Figures 2 to 7 In this embodiment, a semi-premixed internal circulation low nitrogen burner is further provided. Compared with the semi-premixed internal circulation low nitrogen burner in the first embodiment, the semi-premixed internal circulation low nitrogen burner in this embodiment further includes the following structure:

[0041] As an example, there are multiple internal gas channels 6 and multiple internal combustion air mixing channels 7, and the internal gas channels 6 and the internal combustion air mixing channels 7 are arranged in a one-to-one correspondence; the multiple internal gas channels 6 and the multiple internal combustion air mixing channels 7 are arranged circumferentially with the center line of the semi-premixed internal circulation low-nitrogen burner as the axis.

[0042] As an example, the internal gas channel 6 is a tapered channel, and the flow area is minimized at the end where it connects to the internal combustion air mixing channel 7. Specifically, the rear end of the internal gas channel 6 consists of a tapered section followed by a straight section. Due to the Venturi effect, the gas flow rate is high at the constricted portion of the internal gas channel 6, creating a relatively negative pressure environment. This allows the higher-pressure air within the air channel 8 to flow easily into this negative pressure zone, making it easier for the air within the air channel 8 to enter the internal gas-air mixing channel 7. Part of the gas and air are premixed and burned within the internal gas-air mixing channel 7, creating a partial premixing effect. This premixed combustion temperature is more uniform, avoiding the formation of localized high-temperature zones, resulting in a lower peak combustion temperature and effectively reducing the formation of thermal nitrogen oxides. This premixing gun also stabilizes the main flame and provides a heat source for the outer fuel layer. Furthermore, the air outside the internal gas-air mixing channel 7 has a cooling effect on the internal gas-air mixing channel wall 10, preventing burns.

[0043] As an example, the internal combustion gas channel 6 and the internal combustion air mixing channel 7 form a premixing assembly.

[0044] As an example, Figure 5 As shown, the outlet of the internal combustion air mixing channel 7 is a bent portion, which bends toward the refractory castable annular platform 1; the angle α between the bent portion and the center line of the semi-premixed internal circulation low nitrogen burner is 30° to 90°.

[0045] As an example, there are multiple middle-layer gas nozzles 5 and multiple outer-layer gas nozzles 3. The multiple middle-layer gas nozzles 5 are arranged along the circumference of the middle-layer gas ring 4, and the multiple outer-layer gas nozzles 3 are arranged along the circumference of the outer-layer gas ring 2. Specifically, fuel is injected into the combustion area through the multiple outer-layer gas nozzles 3 and the middle-layer gas nozzles 5, enabling multi-stage fuel injection and multi-stage combustion. This also improves fuel and flue gas mixing, effectively controls the combustion reaction rate, reduces the peak combustion temperature, and makes the combustion temperature more uniform. Furthermore, the fuel is injected from different directions through the outer-layer gas nozzles 3 and the middle-layer gas nozzles 5, effectively utilizing the combustion space, allowing the flame to fill the furnace and allowing the furnace walls to fully absorb heat. This not only reduces the peak combustion temperature and thus the generation of nitrogen oxides, but also improves thermal efficiency. The setting of multiple gas nozzles realizes multi-stage combustion, and the injection of multiple gas nozzles makes the fuel injection more uniform; and the injection of gas from multiple nozzles can also better mix the fuel and flue gas, reduce the calorific value of the fuel as much as possible, and effectively control the combustion speed, thereby reducing the generation of thermal nitrogen oxides.

[0046] As an example, the angle γ between the injection direction of the outer gas nozzle 3 and the center line of the semi-premixed internal circulation low nitrogen burner is -10° to 60°. Figure 6 The injection direction of the middle layer gas nozzle 5 and the center line of the semi-premixed low nitrogen burner angle β is 10 ° ~ 70 °, as Figure 4 The middle layer gas nozzles 5 and the outer layer gas nozzles 3 respectively inject fuel into the combustion area at a certain angle. This structure avoids excessive concentration of the fuel injection area, effectively utilizes the combustion space, makes the combustion temperature more uniform, and reduces the generation of thermal nitrogen oxides.

[0047] As an example, the refractory castable annular platform 1 includes a first refractory castable annular platform layer 101, a second refractory castable annular platform layer 102 and a third refractory castable annular platform layer 103 stacked in sequence from the outside to the inside; the outer layer gas channel 11 and the middle layer gas channel 12 are both located in the first refractory castable annular platform layer 101; the injection direction of the outer layer gas nozzle 3 and the injection direction of the middle layer gas nozzle 5 are both toward the second layer 102 of the refractory castable annular platform.

[0048] Specifically, the refractory castable ring platform 1 is divided into the first layer 101, the second layer 102, and the third layer 103. The refractory castable has heat storage capacity, so there is sufficient heat around the refractory castable ring platform 1, which can provide sufficient ignition heat for the fuel and has a strong combustion stabilization effect. The protruding portions of the first layer 101, the second layer 102, and the third layer 103 of the refractory castable ring platform 1 increase the heat storage area, thereby enhancing the heat storage capacity of the refractory castable ring platform 1. This combustion stabilization structure enables the flame to burn stably at an oxygen content of 0-3%.

[0049] As an example, the second surface of the second layer 102 of the refractory castable annular platform includes an inclined surface and a horizontal surface, wherein the inclined surface extends from the first layer of the refractory castable annular platform to the horizontal surface of the second layer of the refractory castable annular platform; the inclination angle δ of the inclined surface is 30° to 60°, such as Figure 7 As shown; the second surface of the second layer 102 of the refractory castable annular platform is provided with a first annular groove 1021, and the second surface of the third layer 103 of the refractory castable annular platform is provided with a second annular groove 1031, the second annular groove 1031 surrounds the periphery of the air channel 8, and the first annular groove 1021 surrounds the periphery of the second annular groove 1031.

[0050] Specifically, if Figure 3 As shown, there is no air radially outside the annular refractory castable platform 1. Therefore, the gas ejected from the outer and middle gas nozzles 3 and 5 is surrounded only by flue gas, leaving the fuel in an oxygen-deficient environment after injection. The outer and middle gas nozzles 3 and 5 are relatively small, allowing the gas to pass through them at a high velocity. The kinetic energy of the gas flow is high, allowing the surrounding flue gas to be drawn into the gas flow. Furthermore, the first and second annular grooves 1021 and 1031 enhance the vortex of the flue gas flow, further enhancing mixing between the gas and the flue gas while cracking the gas into reducing substances such as CO and H+. This structure effectively dilutes the gas to a certain extent, thereby lowering the peak combustion temperature and reducing the formation of thermal nitrogen oxides.

[0051] As an example, the inner wall of the refractory castable annular platform 1 includes an inclined inner wall, so that the diameter of the opening of the air channel 8 on the second surface is larger than the diameter of the opening on the first surface.

[0052] Specifically, the air channel 8 is a gradually expanding structure, and the flow area becomes larger and larger in the direction of gas flow. This structure can allow air to diffuse into the combustion area, fully utilize the combustion space, better fill the furnace flame, and make the combustion temperature more uniform, which not only reduces the generation of nitrogen oxides but also improves the thermal efficiency of the furnace.

[0053] As an example, a flame stabilizing disk 9 is further included, which is located downstream of the air channel 8. The flame stabilizing disk 9 is provided with swirl blades and through holes, and the through holes are connected to the air channel 8. The swirl blades are located on the periphery of the through holes; the internal gas-air mixing channel 7 is located on the outside of the flame stabilizing disk 9.

[0054] Specifically, the flame stabilizing disk 9 is placed at the rear end of the air channel 8, and the center line of the flame stabilizing disk 9 coincides with the center line of the semi-premixed internal circulation low-nitrogen burner. The addition of the flame stabilizing disk 9 blocks the airflow, forming a negative pressure at its rear end, which can entrain the smoke and realize internal circulation of the smoke. Internal circulation of the smoke can reduce the temperature and oxygen content in the combustion area, thereby reducing the combustion peak and further reducing the generation of thermal nitrogen oxides. The flame stabilizing disk 9 is also provided with swirl blades, which can increase the kinetic energy of the air in the radial direction, enhance the mixing of air and gas, achieve uniform combustion, and form a central negative pressure to further entrain the smoke.

[0055] The present invention combines the technical means of flue gas internal circulation, staged combustion, semi-premixing and heat storage and stable combustion, and the design of the hollow flame can effectively reduce the combustion temperature, and can achieve nitrogen oxide emissions of 30mg / Nm3 when burning high calorific value relatively clean fuel without using flue gas external circulation and flameless combustion. 3 The low nitrogen burner in the invention not only has low nitrogen combustion characteristics but also has a good flame filling degree in the furnace, which can improve the thermal efficiency of the furnace.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0057] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A semi-premixed internal circulation low nitrogen burner, characterized in that: include: A refractory castable annular platform, the refractory castable annular platform comprising a first surface and a second surface opposite to each other, an air passage formed on the inner side of the refractory castable annular platform, the air passage extending from the first surface to the second surface; an internal gas passage located in the air passage and extending from the first surface into the air passage; an internal gas-air mixing channel, located in the air channel, with one end connected to the internal gas channel and the other end extending downstream of the second surface; A middle-layer gas channel is located in the annular platform of the refractory castable, and the middle-layer gas channel extends from the first surface to the second surface; a middle-layer gas ring is located on the second surface, surrounds the periphery of the air channel, and is connected to the middle-layer gas channel, and has a one-to-one correspondence with the middle-layer gas channel; a middle-layer gas nozzle is located on the middle-layer gas ring and is connected to the middle-layer gas ring; an outer-layer gas channel is located in the annular platform of the refractory castable, and the outer-layer gas channel extends from the first surface to the second surface; an outer-layer gas ring is located on the second surface, surrounds the periphery of the middle-layer gas ring, and is connected to the outer-layer gas channel, and has a one-to-one correspondence with the outer-layer gas channel; an outer-layer gas nozzle is located on the outer-layer gas ring and is connected to the outer-layer gas ring.

2. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: There are multiple internal gas channels and multiple internal gas-air mixing channels, and the internal gas channels are arranged in a one-to-one correspondence with the internal gas-air mixing channels; the multiple internal gas channels and the multiple internal gas-air mixing channels are circumferentially arranged with the center line of the semi-premixed internal circulation low-nitrogen burner as the axis.

3. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The internal gas channel is a tapered channel, and the flow area of ​​one end of the internal gas channel communicating with the internal gas-air mixing channel is the smallest.

4. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The outlet of the internal gas-air mixing channel is a bent portion, which bends toward the refractory castable annular platform; the angle between the bent portion and the center line of the semi-premixed internal circulation low-nitrogen burner is 30° to 90°.

5. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: There are multiple middle-layer gas nozzles and multiple outer-layer gas nozzles. The multiple middle-layer gas nozzles are arranged along the circumference of the middle-layer gas ring, and the multiple outer-layer gas nozzles are arranged along the circumference of the outer-layer gas ring.

6. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The angle between the injection direction of the outer layer gas nozzle and the center line of the semi-premixed internal circulation low nitrogen burner is -10° to 60°; the angle between the injection direction of the middle layer gas nozzle and the center line of the semi-premixed low nitrogen burner is 10° to 70°.

7. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The refractory castable annular platform includes a first layer of refractory castable annular platform, a second layer of refractory castable annular platform and a third layer of refractory castable annular platform stacked in sequence from the outside to the inside; the outer layer gas channel and the middle layer gas channel are both located in the first layer of the refractory castable annular platform; the injection direction of the outer layer gas nozzle and the injection direction of the middle layer gas nozzle are both toward the second layer of the refractory castable annular platform.

8. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The second surface of the second layer of the refractory castable annular platform includes an inclined surface and a horizontal surface, the inclined surface extends from the first layer of the refractory castable annular platform to the horizontal surface of the second layer of the refractory castable annular platform; the inclination angle of the inclined surface is 30° to 60°; the second surface of the second layer of the refractory castable annular platform is provided with a first annular groove, and the second surface of the third layer of the refractory castable annular platform is provided with a second annular groove, the second annular groove surrounds the periphery of the air channel, and the first annular groove surrounds the periphery of the second annular groove.

9. The semi-premixed internal circulation low nitrogen burner according to claim 1 is characterized in that: The inner wall of the refractory castable annular platform includes an inclined inner wall, so that the diameter of the opening of the air channel at the second surface is larger than the diameter of the opening at the first surface.

10. The semi-premixed internal circulation low nitrogen burner according to claim 1, characterized in that: It also includes a flame stabilizing disk, which is located downstream of the air channel. The flame stabilizing disk is provided with swirl blades and a through hole. The through hole is connected to the air channel, and the swirl blades are located on the periphery of the through hole; the internal gas-air mixing channel is located on the outside of the flame stabilizing disk.

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