Hollow flame low nitrogen burner

Abstract

The present invention provides a hollow flame low-nitrogen burner, comprising: a casting base, an air channel formed on the inner side of the casting base; an internal gas air channel located between the air channel and the casting base; an internal gas channel extending from a first surface into the internal gas air channel; an internal gas nozzle located at one end of the internal gas channel extending into the internal gas air channel; a first flue gas channel of the casting base located within the casting base; a second flue gas channel of the casting base located within the casting base; an external gas-flue gas mixing channel located outside the casting base; and an external gas channel located outside the casting base and extending from one side of the first surface of the casting base into the external gas-flue gas mixing channel. The casting base has a heat storage function, enabling stable combustion of fuel at an oxygen content of 0-3%. The special design prevents flame generation in the center of the burner, and combines low-nitrogen combustion technologies such as premixed combustion, internal flue gas circulation, and staged combustion to ensure the effectiveness and stability of low-oxygen combustion.

Description

Technical Field

[0001] The invention relates to the field of boiler and industrial furnace emission reduction, and in particular to a hollow flame low-nitrogen burner. Background Art

[0002] Currently, the most common nitrogen reduction method used in gas-fired industrial furnaces is a low-nitrogen burner combined with flue gas external recirculation. For boilers burning high-calorific-value, relatively clean fuels like natural gas, this nitrogen reduction method can reduce boiler nitrogen oxide emissions to below 30mg / Nm3. Currently, most low-nitrogen burners on the market use multi-stage combustion and rich-lean combustion technologies to achieve nitrogen reduction combustion. Flue gas external recirculation involves extracting a certain proportion of flue gas from the rear of the furnace and then passing it through a flue gas recirculation pipe to the burner air inlet, where it is mixed with combustion-supporting air before participating in combustion. For high-calorific-value gases such as natural gas, flue gas external recirculation can effectively reduce the peak combustion temperature and oxygen content, thereby reducing the formation of thermal nitrogen oxides.

[0003] However, the application of external flue gas circulation has many disadvantages, such as the appearance of condensed water when the flue gas flows back, and the mixing of externally circulated flue gas into the combustion-supporting air can easily cause vibration. Summary of the Invention

[0004] To achieve the above-mentioned and other related purposes, the present invention provides a hollow flame low-nitrogen burner, comprising: a casting material table, the casting material table comprising a first surface and a second surface opposite to each other, an air channel formed on the inner side of the casting material table, the air channel extending from the first surface to the second surface; an internal gas air channel located between the air channel and the casting material table, the internal gas air channel being parallel to the air channel; an internal gas channel extending from the first surface into the internal gas air channel; an internal gas nozzle located in the internal gas channel extending from the internal gas air channel to the internal gas air channel one end of the pouring material platform; a first flue gas channel of the pouring material platform is located in the pouring material platform, one end is connected to the air channel, and the other end extends to the outer wall of the pouring material platform; a second flue gas channel of the pouring material platform is located in the pouring material platform, one end is connected to the first flue gas channel of the pouring material platform, and the other end extends to the second surface of the pouring material platform; an external gas and flue gas mixing channel is located on the outside of the pouring material platform, and the external gas and flue gas mixing channel is parallel to the air channel; the external gas channel is located on the outside of the pouring material platform, and extends from one side of the first surface of the pouring material platform to the external gas and flue gas mixing channel.

[0005] Optionally, the number of the internal gas and air channels, the number of the internal gas channels, the number of the internal gas nozzles, the number of the first flue gas channels of the casting material platform, the number of the second flue gas channels of the casting material platform, the number of the external gas and flue gas mixing channels and the number of the external gas channels are all multiple; the internal gas and air channels are arranged in a one-to-one correspondence with the internal gas channels, and the multiple internal gas and air channels and the multiple internal gas channels are arranged circumferentially with the center line of the hollow flame low-nitrogen burner as the axis; the first flue gas channel of the casting material platform and the second flue gas channel of the casting material platform are arranged in a one-to-one correspondence, and the multiple first flue gas channels of the casting material platform and the second flue gas channels of the casting material platform are arranged circumferentially with the center line of the hollow flame low-nitrogen burner as the axis; the external gas and flue gas mixing channels are arranged in a one-to-one correspondence with the external gas channels, and the multiple external gas and flue gas mixing channels and the multiple external gas channels are arranged circumferentially with the center line of the hollow flame low-nitrogen burner as the axis.

[0006] Optionally, each of the internal gas channels is provided with a plurality of the internal gas nozzles, and the plurality of the internal gas nozzles form a premixing gun.

[0007] Optionally, the inner wall of the casting table includes a first casting table slope, which extends from the inside of the casting table to the second surface of the casting table, and the angle between the first casting table slope and the center line of the hollow flame low nitrogen burner is 10° to 60°.

[0008] Optionally, a second casting material platform slope is provided inside the second flue gas channel of the casting material platform, and the angle between the second casting material platform slope and the center line of the hollow flame low nitrogen burner is 80° to 120°.

[0009] Optionally, the internal gas and air channel is located between the first flue gas channel of the casting table and the first surface of the casting table, and the distance between one end of the internal gas and air channel away from the internal gas channel and the side wall of the first flue gas channel of the casting table away from the second flue gas channel of the casting table is less than the diameter of the internal gas and air channel.

[0010] Optionally, the internal gas channel is a tapered channel, and the diameter of one end of the internal gas channel extending into the internal gas-air channel is the smallest.

[0011] Optionally, the external gas channel is a tapered channel, and the diameter of one end of the external gas channel extending into the external gas-smoke mixing channel is the smallest.

[0012] As described above, the hollow flame low nitrogen burner of the present invention has the following beneficial effects:

[0013] 1. The pouring material table has a heat storage function, which enables the fuel to burn stably at an oxygen content of 0-3%. The special design prevents flame generation in the center of the burner, and combines low-nitrogen combustion technologies such as premixed combustion, flue gas internal circulation, and staged combustion to ensure the effect and stability of low-oxygen combustion.

[0014] 2. All combustion air in the burner area enters through the internal gas-air channel, entraining high-temperature flue gas to form a flue-air mixture. The mixture exiting the internal gas-air channel is split into three streams: the first stream flows through the air channel, the second stream flows through the first flue gas channel of the casting bed, and the third stream flows through the second flue gas channel of the casting bed. This three-stream mixture heats the casting bed, ensuring stable and continuous heat storage. The second stream of mixed gas can then remix with the gas-flue mixture exiting the external gas-flue mixing channel, further diluting the gas. This prevents condensation and vibration from flue gas backflow.

[0015] 3. No fuel is introduced into the central area of ​​the air passage, so that the flame is hollow. The advantage of a hollow flame is that the temperature at the center of the flame is lower, which can effectively suppress the formation of thermal nitrogen oxides there.

[0016] 4. The rear end of the air channel is expanded to allow air to diffuse and flow into the combustion area, which can make the flame fuller and fully utilize the furnace space. It can not only reduce the peak combustion temperature and the generation of thermal nitrogen oxides, but also improve the thermal efficiency of the furnace.

[0017] 5. The gas is distributed in two layers, inner and outer, and several gas channels are arranged on each layer, so that the gas can be evenly sprayed into the combustion area, making the combustion more uniform and the combustion temperature lower, thereby achieving low-nitrogen combustion.

[0018] 6. The tapered rear end of the external gas channel increases the velocity of the external gas there. Through the Venturi effect, the gas pressure around the rear end of the external gas channel decreases, allowing the surrounding high-temperature flue gas to more easily enter the external gas-flue mixing channel. Within the external gas-flue mixing channel, the flue gas mixes with the fuel. In an oxygen-deficient environment, the fuel decomposes into reducing substances such as CO and H+, and the hot flue gas dilutes the fuel gas. This effectively reduces the calorific value of the fuel gas, controls the combustion velocity, and brings the combustion temperature closer to the mean, avoiding the formation of localized high-temperature zones. Ultimately, this reduces the formation of thermal nitrogen oxides.

[0019] 7. The rear end of the internal gas passage is tapered, accelerating the internal gas at the constriction. Similarly, due to the Venturi effect, the pressure near the rear end of the internal gas passage decreases, making it easier for surrounding air to enter the internal gas and air passage. Several internal gas nozzles are arranged in a spiral pattern, allowing the gas to enter the internal gas and air passage in a spiral pattern. Within the internal gas and air passage, the swirling gas is more easily premixed with the air. Premixed combustion of a portion of the gas and air occurs within the internal gas and air passage. This premixed combustion ensures more uniform combustion, avoids the formation of localized high-temperature zones, and thus reduces the formation of thermal nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a top view of the hollow flame burner provided by the present invention.

[0021] Figure 2 The hollow flame burner provided by the present invention is along Figure 1 Longitudinal cross-sectional structure in the AA direction.

[0022] Figure 3 A side view of the hollow flame burner provided by the present invention.

[0023] Figure 4 This is a gas flow diagram of the hollow flame burner provided by the present invention.

[0024] Figure 5 Schematic diagram of two slope angles of the casting material platform inside the second flue gas channel of the casting material platform in the hollow flame burner provided by the present invention.

[0025] Figure 6 A schematic front view of an internal gas passage with an internal gas nozzle at the top end in the hollow flame burner provided by the present invention.

[0026] Figure 7 A top view of an inner gas passage with an inner gas nozzle at the top end in the hollow flame burner provided by the present invention.

[0027] Figure 8 This is a schematic diagram of the diameter of the internal gas and air channel in the hollow flame burner provided by the present invention and the distance between the internal gas and air channel and the bottom of the first flue gas channel of the casting material platform.

[0028] Component number description: 1. External gas and flue gas mixing channel, 2. External gas channel, 3. Casting platform, 301 first casting platform slope, 302 second casting platform slope, 401 first flue gas channel of casting platform, 402 second flue gas channel of casting platform, 5. Internal gas channel, 6. Internal gas nozzle, 7. Internal gas air channel, 8. Air channel DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] 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" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships 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 operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0032] As mentioned above, most low-nitrogen burners currently on the market use technologies such as multi-stage combustion and rich-lean combustion to achieve nitrogen reduction combustion. Flue gas external circulation involves extracting a certain proportion of flue gas from the rear of the furnace and then passing it through a flue gas circulation duct to the burner air inlet, where it is mixed with the combustion-supporting air before participating in combustion. For high-calorific-value gases such as natural gas, flue gas external circulation can effectively reduce the peak combustion temperature and oxygen content, thereby reducing the formation of thermal nitrogen oxides. However, the use of flue gas external circulation has many disadvantages, such as the formation of condensed water when the flue gas refluxes, and the mixing of the externally recycled flue gas into the combustion-supporting air, which can easily cause vibration.

[0033] Example 1

[0034] See also Figures 1 to 3As shown, the present invention provides a hollow flame low nitrogen burner, comprising: a casting material table 3, the casting material table 3 comprising a first surface and a second surface opposite to each other, an air channel 8 formed on the inner side of the casting material table 3, the air channel 8 extending from the first surface to the second surface; an internal gas air channel 7 located between the air channel 8 and the casting material table 3, the internal gas air channel 7 being parallel to the air channel 8; an internal gas channel 5 extending from the first surface into the internal gas air channel 7; an internal gas nozzle 6 located at one end of the internal gas channel 5 extending into the internal gas air channel 7; a first surface of the casting material table The flue gas channel 401 is located in the casting material platform 3, one end of which is connected to the air channel 8, and the other end extends to the outer wall of the casting material platform 3; the second flue gas channel 402 of the casting material platform is located in the casting material platform 3, one end of which is connected to the first flue gas channel 401 of the casting material platform, and the other end extends to the second surface of the casting material platform 3; the external gas and flue gas mixing channel 1 is located on the outside of the casting material platform 3, and the external gas and flue gas mixing channel 1 is parallel to the air channel 8; the external gas channel 2 is located on the outside of the casting material platform 3, and extends from the side of the first surface of the casting material platform 3 to the external gas and flue gas mixing channel 1.

[0035] Specifically, if Figure 1 As shown, the casting material platform 3 is a ring-shaped casting material platform.

[0036] The hollow flame low nitrogen burner of the present invention has a heat storage function through the casting material platform 3, which enables the fuel to burn stably at an oxygen content of 0-3%, thus ensuring the stability of low oxygen combustion. Figure 4 All combustion air in the burner area enters through the internal gas-air channel 7, entraining high-temperature flue gas to form a flue-air mixture. The mixture flowing out of the internal gas-air channel 7 is split into three streams: the first stream flows out through the air channel 8, the second stream flows out through the first flue gas channel 401 of the casting bed 3, and the third stream flows out through the second flue gas channel 402 of the casting bed. These three streams heat the casting bed 3, ensuring stable and continuous heat storage. Furthermore, the second stream can remix with the gas-flue mixture flowing out of the external gas-flue mixing channel 1, further diluting the gas. There is no condensation generated by flue gas backflow, nor is there any vibration. No fuel is introduced into the central area of ​​the air channel 8, resulting in a hollow flame. The advantage of a hollow flame is that the temperature at the center of the flame is lower, effectively suppressing the formation of thermal nitrogen oxides there.

[0037] Example 2

[0038] Please continue reading Figures 1 to 3This embodiment further provides a hollow flame low nitrogen burner. Compared with the hollow flame low nitrogen burner in the first embodiment, the hollow flame low nitrogen burner in this embodiment further includes the following structure:

[0039] As an example, the number of the internal gas air channels 7, the number of the internal gas channels 5, the number of the internal gas nozzles 6, the number of the first flue gas channels 401 of the casting material platform, the number of the second flue gas channels 402 of the casting material platform, the number of the external gas and flue gas mixing channels 1, and the number of the external gas channels 2 are all multiple; the internal gas air channels 7 are arranged in a one-to-one correspondence with the internal gas channels 5, and the multiple internal gas air channels 7 and the multiple internal gas channels 5 are all centered on the center line of the hollow flame low nitrogen burner as the axis. Circumferentially spaced apart arrangement; the first flue gas channel 401 of the casting material platform is arranged in one-to-one correspondence with the second flue gas channel 402 of the casting material platform, and the plurality of first flue gas channels 401 of the casting material platform and the second flue gas channels 402 of the casting material platform are arranged circumferentially spaced apart with the center line of the hollow flame low nitrogen burner as the axis; the external gas flue gas mixing channel 1 is arranged in one-to-one correspondence with the external gas channel 2, and the plurality of external gas flue gas mixing channels 1 and the plurality of external gas channels 5 are arranged circumferentially spaced apart with the center line of the hollow flame low nitrogen burner as the axis.

[0040] The gas enters the combustion area through the inner gas channel 5 and the outer gas channel 2 respectively, and a plurality of the inner gas channel 5 and the outer gas channel 2 are arranged, so that the gas can be evenly sprayed into the combustion area, which can make the combustion more uniform and the combustion temperature lower, thereby achieving low-nitrogen combustion.

[0041] As an example, Figure 6 and Figure 7 As shown, each of the internal gas channels 5 is provided with a plurality of the internal gas nozzles 6 , the plurality of the internal gas nozzles 6 form a premixing gun, and the plurality of the internal gas nozzles 6 form a spiral shape.

[0042] Specifically, several of the internal gas nozzles 6 form a spiral shape, causing the gas to swirl as it enters the internal gas-air passage 7. Within the internal gas-air passage 7, the swirling gas is more easily premixed with the air for uniformity. A portion of the gas and air are premixed and burned within the internal gas-air passage 7. This premixed combustion ensures more uniform combustion, avoids the formation of localized high-temperature zones, and thereby reduces the formation of thermal nitrogen oxides. This premixing gun stabilizes the flame, providing a heat source for the outer fuel layer, thereby stabilizing the flame generated by the outer fuel layer in a low-oxygen environment. The premixing gun in this example is merely an example and is not intended to be limiting. Any application will be sufficient as long as it can provide a stable and reliable heat source.

[0043] As an example, Figure 5As shown, the inner wall of the casting bed 3 includes a first casting bed slope 301, which extends from the inside of the casting bed 3 to the second surface of the casting bed 3. The angle α between the first casting bed slope 301 and the centerline of the hollow flame low-NOx burner is 10° to 60°. The slope of the first casting bed slope 301 creates a flare at the rear end of the air passage 8. This flare diffuses air into the combustion area, ensuring a full flame and fully utilizing the furnace space. This not only reduces the peak combustion temperature and the generation of thermal NOx, but also improves the furnace's heat absorption capacity and efficiency.

[0044] As an example, Figure 5 As shown, a second casting platform slope 302 is provided inside the second flue gas channel 402 of the casting platform. The angle β between the second casting platform slope 302 and the centerline of the hollow flame low-nitrogen burner is 80° to 120°. This slope facilitates the entry of flue gas from the internal combustion gas into the first flue gas channel 401 and the second flue gas channel 402 of the casting platform.

[0045] Specifically, the rear end of the casting platform 3 is provided with the first and second flue gas channels 401 and 402 of the casting platform, which are communicated with the air channel 8. The first and second flue gas channels 401 and 402 of the casting platform are arranged circumferentially with the center line of the hollow flame low nitrogen burner as the axis. Figure 1 Eight are shown, but in other examples, the number is not limited to this. The central axis of the first flue gas channel 401 of the casting bed is perpendicular to the centerline of the burner, and the first flue gas channel 401 of the casting bed extends radially outward through the casting bed. The outlet of the second flue gas channel 402 of the casting bed faces the furnace, and the second flue gas channel 402 of the casting bed extends rearward and through the casting bed.

[0046] As an example, the internal gas and air channel 7 is located between the first flue gas channel 401 of the casting platform and the first surface of the casting platform 3, and the distance H between the end of the internal gas and air channel 7 away from the internal gas channel 7 and the side wall of the first flue gas channel 401 of the casting platform away from the second flue gas channel 402 of the casting platform is less than the diameter D of the internal gas and air channel 7. Figure 8 The above structure can facilitate the diffusion of the smoke flowing out of the inner gas and air channel 7 into the smoke channel of the casting platform.

[0047] As an example, the internal gas passage 5 is a tapered passage, and the diameter of one end of the internal gas passage 5 extending into the internal gas and air passage 7 is the smallest.

[0048] As an example, the internal combustion gas channel 5 and the internal combustion air channel 7 form a premixing assembly.

[0049] Specifically, the rear end of the internal gas passage 5 is tapered, accelerating the internal gas at the constriction. Similarly, due to the Venturi effect, the pressure near the rear end of the internal gas passage 5 decreases, making it easier for surrounding air to enter the internal gas and air passage 5. Several internal gas nozzles 6 are formed in a spiral shape, allowing the gas to enter the internal gas and air passage 5 in a spiral pattern. Within the internal gas and air passage 5, the swirling gas is more easily premixed with the air for uniform combustion. Premixed combustion allows for more uniform combustion, avoids the formation of localized high-temperature zones, and thus reduces the formation of thermal nitrogen oxides.

[0050] As an example, the external gas channel 2 is a tapered channel, and the diameter of the end of the external gas channel 2 extending into the external gas-smoke mixing channel 1 is the smallest.

[0051] Specifically, the tapered rear end of the external gas channel 2 increases the velocity of the external gas there. Through the Venturi effect, the gas pressure around the rear end of the external gas channel 2 decreases, allowing the surrounding high-temperature flue gas to more easily enter the external gas-flue gas mixing channel 1. Within the external gas-flue gas mixing channel 1, the flue gas mixes with the fuel. In an oxygen-deficient environment, the fuel decomposes into reducing substances such as CO and H+, and the hot flue gas dilutes the fuel gas. This effectively reduces the calorific value of the fuel gas, controls the combustion velocity of the fuel gas, brings the combustion temperature closer to the mean, avoids the formation of localized high-temperature zones, and ultimately reduces the generation of thermal nitrogen oxides.

[0052] Through structural innovation, this invention eliminates flame generation in the burner's center, allowing high-temperature flue gas to circulate internally to the combustion zone to participate in combustion. This reduces the fuel's calorific value, enables low-oxygen combustion, and reduces the generation of fuel-derived nitrogen oxides during combustion. Furthermore, combined with premixed combustion and staged combustion, this method achieves uniform combustion, lowers peak combustion temperature, and thus reduces the generation of nitrogen oxides.

[0053] 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.

[0054] 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 hollow flame low nitrogen burner, characterized in that: include: A casting platform, the casting platform comprising a first surface and a second surface opposite to each other, an air passage formed inside the casting platform, the air passage extending from the first surface to the second surface; an internal gas air passage, located inside the air passage, the internal gas air passage being parallel to the air passage; an internal gas passage extending from the first surface into the internal gas and air passage; an internal gas nozzle, located at one end of the internal gas passage extending into the internal gas air passage; a first smoke channel of the casting platform, located in the casting platform, with one end connected to the air channel and the other end extending to the outer wall of the casting platform; a second fume duct of the casting material platform, located in the casting material platform, with one end connected to the first fume duct of the casting material platform and the other end extending to the second surface of the casting material platform; An external gas and smoke mixing channel is located outside the casting material platform, and the external gas and smoke mixing channel is parallel to the air channel; The external gas channel is located outside the casting material platform and extends from one side of the first surface of the casting material platform to the external gas and smoke mixing channel.

2. The hollow flame low nitrogen burner according to claim 1, characterized in that: The number of the internal gas and air channels, the number of the internal gas channels, the number of the internal gas nozzles, the number of the first flue gas channels of the casting material platform, the number of the second flue gas channels of the casting material platform, the number of the external gas and flue gas mixing channels, and the number of the external gas channels are all multiple; the internal gas and air channels are arranged in a one-to-one correspondence with the internal gas channels, and the multiple internal gas and air channels and the internal gas channels are arranged circumferentially with the center line of the hollow flame low-nitrogen burner as the axis; the first flue gas channel of the casting material platform and the second flue gas channel of the casting material platform are arranged in a one-to-one correspondence, and the multiple first flue gas channels of the casting material platform and the multiple second flue gas channels of the casting material platform are arranged circumferentially with the center line of the hollow flame low-nitrogen burner as the axis; The external gas and flue gas mixing channels are arranged in one-to-one correspondence with the external gas channels, and a plurality of the external gas and flue gas mixing channels and a plurality of the external gas channels are arranged circumferentially with the center line of the hollow flame low nitrogen burner as the axis.

3. The hollow flame low nitrogen burner according to claim 2, characterized in that: Each of the internal gas channels is provided with a plurality of the internal gas nozzles, and the plurality of the internal gas nozzles form a premixing gun.

4. The hollow flame low nitrogen burner according to claim 1, characterized in that: The inner wall of the casting material platform includes a first casting material platform slope, which extends from the inside of the casting material platform to the second surface of the casting material platform. The angle between the first casting material platform slope and the center line of the hollow flame low nitrogen burner is 10° to 60°.

5. The hollow flame low nitrogen burner according to claim 4, characterized in that: A second casting material platform slope is provided inside the second flue gas channel of the casting material platform, and the angle between the second casting material platform slope and the center line of the hollow flame low nitrogen burner is 80° to 120°.

6. The hollow flame low nitrogen burner according to claim 1, characterized in that: The internal gas and air channel is located between the first flue gas channel of the casting platform and the first surface of the casting platform, and the distance between one end of the internal gas and air channel away from the internal gas channel and the side wall of the first flue gas channel of the casting platform away from the second flue gas channel of the casting platform is less than the diameter of the internal gas and air channel.

7. The hollow flame low nitrogen burner according to claim 1, characterized in that: The internal gas passage is a tapered passage, and the diameter of one end of the internal gas passage extending into the internal gas and air passage is the smallest.

8. The hollow flame low nitrogen burner according to claim 1, characterized in that: The external gas channel is a tapered channel, and the diameter of one end of the external gas channel extending into the external gas-smoke mixing channel is the smallest.

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