A low nitrogen burner

Abstract

The present invention discloses a low-nitrogen burner. The disclosed scheme includes a combustion mixing component, a fire detection and ignition device; the combustion mixing component includes an outer tube, an inner tube and a flame stabilizing tube; the flame stabilizing tube is axially arranged at an axial end of the outer tube, and the flared end of the flame stabilizing tube is a gas combustion outlet; there is a gap between the outer wall of the inner tube and the inner wall of the outer tube to form a gas channel, and the gas channel is connected to the gas inlet and the multiple primary through holes, and multiple secondary through holes are arranged on the gas channel along the circumference, and some secondary gas nozzles are located in the flame stabilizing tube; the fire detection and ignition device are installed in the inner tube through the air inlet. The center of the burner of the present invention, that is, the primary combustion part, adopts semi-premixing technology to form low-temperature homogeneous flue gas in the center of the burner, effectively improving the low-nitrogen effect; the burner head is designed with a thick and thin separation structure to thoroughly perform secondary fuel grading, deviate from the chemical reaction equivalence ratio reaction, and reduce nitrogen oxides.

Description

Technical Field

[0001] The present invention relates to the technical field of gas burners, and in particular to a burner with low NOx content generated by gas combustion, namely a low-nitrogen burner. Background Art

[0002] With the vigorous promotion of "coal to gas", a large amount of coal is being replaced by natural gas, coke oven gas and other fuel gases. Gas is indeed cleaner than coal, and the emission of major pollutants is also lower. Although the NOx (about 100mg / Nm3) produced by gas combustion is only 30% of that of coal, its emission level is still at the same order of magnitude. In fact, "coal to gas" only reduces fuel-type nitrogen oxides. Air is needed as a combustion aid when gas is burned, and the high temperature of combustion also causes N2 in the air to be oxidized to generate NOx and discharged into the atmosphere.

[0003] Since 2017, the country and various regions have issued a number of low-nitrogen environmental protection policies as standards for nitrogen oxide emissions. At the same time, low-nitrogen technology has gradually been implemented in many industries such as small and medium-sized boilers, steel industry gas boilers, and power plant gas boilers. From the perspectives of cost reduction and technological development, the optimization and upgrading of low-nitrogen combustion technology is imminent. The existing mainstream technology mainly adopts a double swirl structure design, and some optimized and improved technologies adopt a grading technology. The grading technology is mainly based on fuel grading, and the fuel is sprayed through several small spray guns to form several small flame modes at the burner mouth. The purpose is to reduce the high-temperature combustion area and inhibit the generation of nitrogen oxides. The air is completely ejected through the swirl blades, and all the air and fuel are mixed and reacted, and the fuel reacts completely through diffusion combustion. This technology is difficult to meet the existing low-nitrogen emission standards. Summary of the invention

[0004] In view of the defects or shortcomings of the prior art, the present invention provides a low-nitrogen burner.

[0005] To this end, the low nitrogen burner provided by the present invention includes a combustion mixing component, a fire detection and ignition device; the combustion mixing component includes:

[0006] An outer cylinder, wherein a gas inlet and an air inlet are provided on the outer cylinder;

[0007] An inner cylinder, wherein a plurality of primary through holes are arranged on the side wall of the inner cylinder in the circumferential direction, and a primary gas pipe is installed on each primary through hole, and each primary gas pipe is located inside the inner cylinder and points to the center of the inner cylinder; a primary gas nozzle is installed at the end of each primary gas pipe away from the primary through hole;

[0008] The flame stabilizing tube is a conical tube structure, and a plurality of mounting through holes are arranged on the side wall of the flame stabilizing tube along the circumferential direction;

[0009] The flame stabilizing tube is axially arranged at an axial end of the outer tube, the flared end of the flame stabilizing tube is a gas combustion outlet, and the flared end is far away from the outer tube, the inner tube is axially installed in the outer tube, and the flame stabilizing tube and the air inlet are axially located on both sides of the multiple primary gas nozzles, and the air inlet and the flame stabilizing tube are axially spaced from the multiple primary gas pipes, and the air inlet, the interior of the inner tube and the flame stabilizing cover are in communication;

[0010] A gap exists between the outer wall of the inner tube and the inner wall of the outer tube to form a gas channel, and the gas channel is connected to the gas inlet and the plurality of primary through holes;

[0011] A plurality of secondary through holes are arranged on the gas passage along the circumferential direction, and a secondary gas nozzle is installed at the gas outlet of each secondary through hole. Some of the plurality of secondary gas nozzles are axially located between the flame stabilizing tube and the plurality of primary gas nozzles, and the remaining secondary gas nozzles pass through the installation through the corresponding secondary through holes and are located in the flame stabilizing tube;

[0012] The fire detector is installed in the inner tube through the air inlet, and the working end of the fire detector is located between multiple primary gas nozzles and the air inlet. The ignition device is installed in the inner tube through the air inlet, and the ignition head of the ignition device is radially located beside the working end of the fire detector.

[0013] In a further embodiment, the low nitrogen burner of the present invention further comprises an air swirl device, wherein the air swirl device comprises a plurality of blades, wherein the plurality of blades are installed in the inner tube and are located between the first-stage gas nozzle and the air inlet.

[0014] In a further solution, the fire detection is arranged along the axial direction, and the fire detection head is located at the center of multiple primary gas nozzles, and the ignition device is arranged obliquely relative to the axis.

[0015] In a further solution, the number of the secondary through holes is greater than the number of the primary through holes.

[0016] In a further solution, the secondary gas nozzle located at the constricted end of the flame stabilizing tube and the secondary gas nozzle located in the flame stabilizing tube are spaced apart in the circumferential direction.

[0017] In a further solution, the gas outlet of the secondary through hole is a corresponding secondary through hole or a secondary gas pipe is installed at the secondary through hole to form a gas outlet.

[0018] In a further embodiment, the low nitrogen burner of the present invention further comprises a central tube, wherein radial constrictions are provided between opposite side walls of the central tube; the central tube is axially located between the flame stabilizing tube and a plurality of primary gas nozzles, and the air inlet, the inner tube, the central tube and the flame stabilizing tube are connected. In a further embodiment, the cone angles on both sides of the radial constriction are different, and the cone angle on the side close to the primary gas nozzle is larger than the cone angle on the other side. In a further embodiment, the cone angle on the side close to the primary gas pipe is 10°-25°, and the cone angle on the other side is 8°-15°.

[0019] In a further solution, the axial spacing between the radial section where the multiple secondary gas nozzles located in the flame stabilizing tube are located and the radial section where the multiple gas nozzles located at the constricted end of the flame stabilizing tube are located is 0.25-0.5 times the inner diameter of the constricted end of the flame stabilizing tube.

[0020] In a further embodiment, the axial distance between the radial section where the plurality of primary gas pipes are located and the outlet of the expanded end of the flame stabilizing tube is 0.8-1.5 times the inner diameter of the contracted end of the flame stabilizing tube.

[0021] In a further solution, the gas inlet and the air inlet are arranged at an axial end of the outer tube, and the end is provided with a radially enlarged cavity, the air inlet is located at the center of the end, and the gas inlet deviates from the center.

[0022] In a further embodiment, the low nitrogen burner of the present invention further comprises an air intake housing, which is provided with an air inlet, a circulating flue gas inlet and an ammonia water inlet, and the air intake housing is installed at the air inlet. In a further embodiment, it further comprises a gas distribution cylinder, which is provided with a plurality of through holes or through grooves, and the gas distribution cylinder is connected to the air inlet and is located in the air intake housing.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The burner center of the present invention, i.e., the primary combustion part, adopts semi-premixing technology to form low-temperature homogeneous flue gas in the burner center, effectively improving the low-nitrogen effect; the burner head is designed with a thick and thin separation structure to thoroughly perform secondary fuel grading and deviate from the chemical reaction equivalence ratio reaction to reduce nitrogen oxides.

[0025] In addition, the low-nitrogen burner is designed with a circulating flue gas inlet (FGR interface) and an ammonia water inlet, which can adapt to a variety of fuels and various complex on-site conditions. The FGR interface of the general air inlet and the ammonia water nozzle can be used in a selective manner according to the on-site conditions to reduce nitrogen oxides.

[0026] If the on-site space is large, you can choose FGR design, arrange the pipeline, and add FGR system. This technology is very mature and mature system can be directly adopted. If the on-site space is relatively small, you can choose ammonia nozzle. Ammonia enters the combustion zone through air and a reduction reaction occurs, which can effectively reduce nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the appearance structure of the burner of the present invention;

[0028] Figure 2 for Figure 1 A longitudinal cross-sectional view of

[0029] Figure 3 for Figure 2 Schematic diagram of the combustion mixing component structure;

[0030] Figure 4 for Figure 1 Schematic diagram of the interior of the primary combustion zone;

[0031] Figure 5 It is a schematic diagram of a burner equipped with an air swirl device;

[0032] Figure 6 The following is an example of a specific structural dimension of the burner of the present invention (unit: mm). DETAILED DESCRIPTION

[0033] Unless otherwise specified, the terms or methods in this article are understood by ordinary technicians in the relevant fields or implemented by existing relevant methods.

[0034] The directional or orientation terms such as axial, radial, inner, outer, end, side, circumferential, and lateral described herein are consistent with the corresponding directions or orientations in the drawings. However, it should be noted that the corresponding directions or orientations in the drawings of the specification only represent an example of the present invention, and the equivalent adjustments and conversions made by those skilled in the art based on the concept and scheme of the present invention are within the protection scope of the present invention.

[0035] In order to illustrate the component structure of the present invention, this article adopts cylinder, tube, cone to define the structure of the corresponding component, and the structural meaning of these words or phrases is understood according to the general understanding of technicians in the relevant field.

[0036] The ignition device and flame detection device used in the burner of the present invention can use existing commercially available products.

[0037] The following are specific embodiments provided by the inventor to further illustrate the present invention.

[0038] Embodiment 1:

[0039] refer to Figure 1-4As shown, the low nitrogen burner of the present invention comprises a combustion mixing assembly, an ignition device 12 and a fire detector 13, and the fire detector is provided with a cooling water interface 13-1 externally;

[0040] See also Figure 2 and 3 As shown, the combustion mixing assembly mainly includes an outer tube 1, an inner tube 2 and a flame stabilizing tube 3, wherein: the outer tube 1 is provided with a gas inlet 1-1 and an air inlet 1-3. The positions of the two gas inlets on the outer tube need to be determined based on the actual installation environment in addition to taking into account the working requirements of the entire assembly. Figure 1 In the product shown, the gas inlet and the air inlet are both opened at one end of the outer tube, and the air inlet is located in the center of the end, and the gas inlet is offset from the center. In some schemes, a radial extension cavity 1-2 is provided at the end of the outer tube, and the gas inlet 1-1 is arranged on the radial extension cavity; a plurality of primary through holes are opened on the side wall of the inner tube 2 along the circumferential direction, and a primary gas pipe 4 is installed on each primary through hole, each primary gas pipe is located in the inner tube, and each gas pipe points to the center of the inner tube but does not intersect, and a primary gas nozzle 5 is installed at the end of each gas pipe away from the corresponding through hole; the flame stabilizing tube 3 is a conical tube structure, and a plurality of mounting holes 3-1 are opened on the side wall of the flame stabilizing tube along the circumferential direction; the assembly method of the components is: taking the axial direction of the outer tube as a reference, the flame stabilizing tube is arranged (directly installed or installed by other components) at one axial end of the outer tube, such as Figure 1 The product structure shown is that the flame stabilizing tube is arranged at the end opposite to the end where the air inlet is located, and the flared end of the flame stabilizing tube serving as the gas combustion outlet is far away from the outer tube 1, the inner tube is axially installed in the outer tube, and the flame stabilizing tube and the air inlet are respectively located on both sides of the multiple first-level gas nozzles in the axial direction, and a distance is provided between the air inlet and the flame stabilizing tube and the first-level gas nozzle, and the air inlet, the inner tube and the flame stabilizing tube are communicated; at the same time, a gap is provided between the outer wall of the inner tube 2 and the inner wall of the outer tube 1 to form a gas channel 6, and the gas channel is communicated with the gas inlet 1-1 and each first-level through hole on the outer tube, and a plurality of second-level through holes are circumferentially provided on the gas channel, and a second-level gas nozzle is installed at the gas outlet of each second-level through hole, and some of the multiple second-level gas nozzles are axially located between the flame stabilizing tube and the multiple first-level gas nozzles, that is, located outside the flame stabilizing tube, and the remaining second-level gas nozzles are located in the flame stabilizing tube through the corresponding gas outlet through the installation through holes on the flame stabilizing tube;

[0041] The fire detector is installed in the inner cylinder through the air inlet, and the working end of the fire detector is located between multiple primary gas nozzles and the air inlet. The ignition device is installed in the inner cylinder through the air inlet, and the ignition head of the ignition device is radially located beside the working end of the fire detector.

[0042] During operation, the burner of the present invention is installed so that combustion occurs in the furnace, the incoming air enters the inner tube, and after the gas enters the gas channel, part of it is ejected into the first-level gas nozzle through the first-level gas pipe, and then ignited to burn. The fire detection is used to detect whether the ignition device is operating normally and feedback a signal, and part of the gas flows to the second-level gas nozzle. The gas ejected from the second-level gas nozzle located outside the flame-stabilizing tube burns with the participation of air or oxygen in the furnace, and the gas ejected from the second-level gas nozzle located inside the flame-stabilizing tube burns with excessively rich fuel. During the process, the first-level oxygen-enriched combustion process can be completed by controlling the combustion temperature of the first-level combustion area. The second-level fuel is burned through concentrated and thin combustion at a distance from the first-level combustion area, so that the combustion deviates from the chemical reaction equivalence ratio, and at the same time, the remaining fuel is completely burned, and finally the generation of nitrogen oxides is suppressed. The component head performs secondary classification on the second-level fuel, and adopts a flame-stabilizing hood to make the classification effect more thorough. The flame length is elongated through the concentrated and thin combustion structure to form a zoned combustion, avoid the generation of local high-temperature areas, and suppress the generation of nitrogen oxides. At the same time, the second-level fuel is ejected through the inner and outer nozzles at a certain distance, which can also effectively reduce nitrogen oxides.

[0043] The combustion mixing component of the present invention can adopt a semi-premixed structure at the primary combustion site. An optional solution is that the number of secondary through holes is greater than the number of primary through holes (e.g., the number of secondary through holes can be set to 8-24, and the number of primary through holes can be set to 4-12) in the specific structure, so that the center of the burner, i.e., the primary combustion site, forms a low-temperature (1100K-1400K) homogeneous flue gas. The nitrogen oxide generation rate in this temperature range is low, which can ensure the stable combustion of the mixture in the center of the component, thereby effectively reducing the amount of nitrogen oxide generation. Combined with the subsequent multiple staged combustion of the fuel, the thick and thin separation is carried out at the burner mouth, so that the chemical reaction of a large amount of secondary fuel deviates from the chemical reaction equivalence ratio, reduces the local high-temperature area, and inhibits the generation of nitrogen oxides.

[0044] Embodiment 2:

[0045] To ensure uniform distribution of gas, in some schemes, based on the scheme of Example 1, the secondary gas nozzles located in the flame stabilizing tube and the secondary gas nozzles located outside the flame stabilizing tube are arranged at intervals in the circumferential direction. That is, from the perspective of multiple secondary through holes, a secondary gas nozzle connected to a through hole is located outside the flame stabilizing tube, and the adjacent secondary gas nozzle is located inside the flame stabilizing tube.

[0046] Embodiment 3:

[0047] In some other solutions, based on the content of the above-mentioned embodiment 1 or embodiment 2, the axial position of the multiple secondary through holes depends on the axial length of the outer cylinder and the inner cylinder, and may also depend on the installation environment and assembly requirements. Figure 1As shown, multiple secondary through holes are axially located between the flame stabilizing tube and multiple primary gas nozzles. Under this structure, the corresponding gas channels extend axially to the above-mentioned corresponding positions, and each secondary through hole is connected to the secondary gas pipe 8 to form a corresponding gas outlet, and is used to connect the gas outlets located inside and outside the flame stabilizing tube with different axial lengths to meet the needs of the corresponding secondary gas nozzle working installation.

[0048] Embodiment 4:

[0049] Different from Example 3, in some schemes, the secondary gas nozzle located outside the flame stabilizing tube is directly installed at the corresponding secondary through hole, and the secondary gas nozzle located inside the flame stabilizing tube is installed and connected through the secondary gas pipe. In this scheme, the corresponding gas channel extends axially to the working position where the external secondary gas nozzle is located.

[0050] Embodiment 5:

[0051] On the basis of the scheme described in the above embodiment, a further scheme also includes a central tube 7. In particular, for low calorific value gas (fuel calorific value is less than or equal to coke oven gas calorific value), this structure can accelerate the occurrence of mixing and combustion reactions. A radial constriction is provided between the opposite side walls of the central tube 7. The central tube 7 is axially installed between the flame stabilizing tube and multiple primary gas nozzles. At the same time, the center tube is connected to the flame stabilizing tube and the inner tube. The flue gas and the remaining air generated after the primary gas combustion pass through the center tube to the flame stabilizing tube. In the preferred scheme, the cone angles on both sides of the radial constriction of the central tube are different in size, and the cone angle close to the primary gas nozzle side is larger than the cone angle on the other side. For example, the cone angle close to the primary gas pipe side can be 10°-25°, and the cone angle on the other side can be 8°-15°.

[0052] Embodiment 6:

[0053] A further preferred scheme of the scheme described in the above embodiment is that, in order to thoroughly grade the secondary fuel gas inside and outside the flame stabilizing tube, the axial spacing between the radial section where the multiple secondary fuel gas nozzles located in the flame stabilizing tube and the radial section where the multiple fuel gas nozzles located at the necked end of the flame stabilizing tube are located is 0.25-0.5 times the internal diameter of the necked end of the flame stabilizing tube.

[0054] Embodiment 7:

[0055] Some preferred schemes of the scheme described in the above embodiment are that, in order to ensure the formation of low-temperature homogeneous flue gas in the primary central combustion zone and enhance the fuel analysis effect, the axial distance between the radial section where the multiple primary gas pipes are located and the outlet of the expanded end of the flame stabilizing tube is 0.8-1.5 times the internal diameter of the contracted end of the flame stabilizing tube.

[0056] Embodiment 8:

[0057] This embodiment is a preferred solution of Embodiment 1, wherein the fire detector is arranged along the axis, and the fire detection head is located at the center of multiple primary gas nozzles. The ignition device is specifically a permanent lamp that is inclined relative to the axis, generally less than 30°, to ensure that the fire detection of the permanent lamp is easily captured by the fire detector. The fire detection module can feedback the fire detection signal with high precision to ensure safe and stable operation of the system.

[0058] Embodiment 9:

[0059] In further schemes, such as Figure 5 As shown, the low nitrogen burner of the present invention is also provided with an air swirl device, specifically a plurality of blades 14, which are installed in the inner tube and located between the primary gas nozzle and the air inlet. In the specific scheme, considering the need to install the fire detection and ignition device, a fire detection installation tube 11 is provided in the center of the plurality of blades, and an ignition device installation hole is opened on one or several blades, which is off-center.

[0060] Embodiment 10:

[0061] See also Figure 1 , 2 As shown in Figures 5 and 5, based on the above-mentioned embodiment scheme, the low nitrogen burner also includes an air intake housing 9, which is installed at the air inlet, and the air intake housing is provided with an air inlet 9-1, an ammonia inlet 9-3 and a circulating flue gas inlet 9-2. In a further preferred scheme, a gas uniform distribution cylinder 10 is also included, and a plurality of grooves or holes (not shown in the figure) are provided on the uniform distribution cylinder. The gas uniform distribution cylinder 10 is connected to the air inlet and is located in the air intake housing 9. The uniform distribution cylinder can change the direction of the incoming gas to enter along the axial direction of the air inlet, and the grooves or holes provided thereon can evenly mix the air, ammonia or / and the circulating flue gas. In this scheme, the circulating flue gas inlet and the air inlet are provided on the same housing, so that the air is diluted before entering the combustion zone, thereby reducing the temperature of the combustion zone and inhibiting the generation of nitrogen oxides.

[0062] The specific burner size of the structure of this embodiment is as follows: Figure 6 As shown, the number of primary through holes is 8, the number of secondary through holes is 24, and the inner and outer secondary gas nozzles are arranged at intervals. Figure 6 The burner shown was sent to Shanghai Special Equipment Testing Institute for testing. Under the test conditions of air, gas and flue gas, the nitrogen oxide emission value was 62mg / Nm3 at low operating conditions (25% load) and 59mg / Nm3 at full load operation.

[0063] Under the test conditions of air, gas and ammonia water, the nitrogen oxide emission value at low working conditions (25% load) is: 65mg / Nm3;

[0064] Under the test conditions of air and gas, the nitrogen oxide emission value at low operating conditions (25% load) is 92 mg / Nm3.

[0065] Comparative Example 1:

[0066] The comparison ratio Figure 6 The structure shown is different in that the burner is not equipped with a flame stabilizing tube, and the secondary gas nozzles are all located at the external secondary gas nozzle position. The burners are tested under the same conditions (test conditions of air, gas and flue gas), and the test is carried out within a working load of 30%-100%, and the emission value is between 70-85mg / Nm3.

[0067] Embodiment 7:

[0068] This embodiment and Figure 6 The difference from the structure shown is that when there is no central flame-stabilizing cone 7, the same conditions (test conditions of air, gas and flue gas) are tested, and the burner with a fuel calorific value less than or equal to the calorific value of coke oven gas operates unstably, and the nitrogen oxide emission index fluctuates greatly, generally fluctuating within a range of 20%. If the emission value is 80 mg / Nm3, the emission value will fluctuate within the range of 64 mg / Nm3 to 96 mg / Nm3.

[0069] Considering the actual processing conditions and assembly requirements, two or more related components of the components of the present invention can be processed into an integrated structure, such as: the flame stabilizing cover and the inner cylinder can be processed into an integrated structure in some schemes; the air swirl device 14 can be used as an integral component, specifically, each blade can be installed in a short cylinder, and then the short cylinder is installed in the corresponding part of the inner cylinder. In terms of specific connection or installation, the assembly of the components of the present invention is mainly welding, among which the ever-burning lamp 1 exists as a separate component, which can be disassembled and replaced at any time, connected by flange bolts, and a metal winding gasket is added in the middle for sealing.

[0070] The above embodiments are only some examples of the present invention. It should be noted that equivalent replacements or improvements made by those skilled in the art based on the disclosure of the present invention are all within the protection scope of the present invention.

Claims

1. A low nitrogen burner, characterized in that: Includes combustion mixing components, fire detection and ignition devices; The combustion mixing assembly comprises: An outer cylinder, wherein a gas inlet and an air inlet are provided on the outer cylinder; An inner cylinder, wherein a plurality of primary through holes are arranged on the side wall of the inner cylinder in the circumferential direction, and a primary gas pipe is installed on each primary through hole, and each primary gas pipe is located inside the inner cylinder and points to the center of the inner cylinder; a primary gas nozzle is installed at the end of each primary gas pipe away from the primary through hole; The flame stabilizing tube is a conical tube structure, and a plurality of mounting through holes are arranged on the side wall of the flame stabilizing tube along the circumferential direction; The flame stabilizing tube is axially arranged at an axial end of the outer tube, the flared end of the flame stabilizing tube is a gas combustion outlet, and the flared end is far away from the outer tube, the inner tube is axially installed in the outer tube, and the flame stabilizing tube and the air inlet are axially located on both sides of the multiple primary gas nozzles, and the air inlet and the flame stabilizing tube are axially spaced from the multiple primary gas pipes, and the air inlet, the interior of the inner tube and the flame stabilizing tube are in communication; A gap exists between the outer wall of the inner tube and the inner wall of the outer tube to form a gas channel, and the gas channel is connected to the gas inlet and the plurality of primary through holes; A plurality of secondary through holes are arranged on the gas passage along the circumferential direction, and a secondary gas nozzle is installed at the gas outlet of each secondary through hole. Some of the plurality of secondary gas nozzles are axially located between the flame stabilizing tube and the plurality of primary gas nozzles, and the remaining secondary gas nozzles pass through the installation through the corresponding secondary through holes and are located in the flame stabilizing tube; The fire detector is installed in the inner tube through the air inlet, and the working end of the fire detector is located between multiple primary gas nozzles and the air inlet. The ignition device is installed in the inner tube through the air inlet, and the ignition head of the ignition device is radially located beside the working end of the fire detector.

2. The low nitrogen burner according to claim 1, characterized in that: It also includes an air swirl device, which includes a plurality of blades. The plurality of blades are installed in the inner tube and are located between the first-stage gas nozzle and the air inlet.

3. The low nitrogen burner according to claim 1, characterized in that: The fire detection is arranged along the axial direction, and the fire detection head is located at the center of a plurality of primary fuel gas nozzles, and the ignition device is arranged obliquely relative to the axial direction.

4. The low nitrogen burner according to claim 1, characterized in that: The number of the secondary through holes is greater than the number of the primary through holes.

5. The low nitrogen burner according to claim 1, characterized in that: The secondary gas nozzle located at the constricted end of the flame stabilizing tube and the secondary gas nozzle located in the flame stabilizing tube are arranged at intervals in the circumferential direction.

6. The low nitrogen burner according to claim 1, characterized in that: The gas outlet of the secondary through hole is a corresponding secondary through hole or a secondary gas pipe is installed at the secondary through hole to form a gas outlet.

7. The low nitrogen burner according to claim 1, characterized in that: It also includes a central tube, in which radial constrictions are arranged between opposite side walls; the central tube is axially located between the flame stabilizing tube and a plurality of primary gas nozzles, and the air inlet, the inner tube, the central tube and the flame stabilizing tube are connected.

8. The low nitrogen burner according to claim 7, characterized in that: The cone angles on the two axial sides of the radial necking are different in size, and the cone angle on the side close to the primary gas nozzle is larger than the cone angle on the other side.

9. The low nitrogen burner according to claim 8, characterized in that: The cone angle on the side close to the primary gas pipe is 10°-25°, and the cone angle on the other side is 8°-15°.

10. The low nitrogen burner according to claim 1, characterized in that: The axial spacing between the radial section where the multiple secondary gas nozzles located in the flame stabilizing tube are located and the radial section where the multiple gas nozzles located at the reduced end of the flame stabilizing tube are located is 0.25-0.5 times the inner diameter of the reduced end of the flame stabilizing tube.

11. The low nitrogen burner according to claim 1, characterized in that: The axial distance between the radial section where the multiple primary gas pipes are located and the outlet of the expanded end of the flame stabilizing tube is 0.8-1.5 times the inner diameter of the contracted end of the flame stabilizing tube.

12. The low nitrogen burner according to claim 1, characterized in that: The gas inlet and the air inlet are arranged at an axial end of the outer cylinder, and the end is provided with a radially enlarged cavity, the air inlet is located at the center of the end, and the gas inlet deviates from the center.

13. The low nitrogen burner according to claim 1, characterized in that: It also includes an air intake shell, which is provided with an air inlet, a circulating smoke inlet and an ammonia water inlet, and the air intake shell is installed at the air inlet.

14. The low nitrogen burner according to claim 10, characterized in that: It also includes a gas evenly distributing cylinder, which is provided with a plurality of through holes or through grooves. The gas evenly distributing cylinder is connected to the air inlet, and the gas evenly distributing cylinder is located in the air inlet housing.

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