CN212108400U - Low NOx self-preheating high-speed burner - Google Patents

Abstract

The utility model relates to a low NOx self preheating-type high-speed nozzle belongs to the nozzle field. The burner changes the structural form of an ignition combustion chamber, an outer air channel, an inner air channel, a secondary air channel and a primary air nozzle are correspondingly formed, and the spraying position of main fuel gas is positioned at the front half part of a necking section of the ignition combustion chamber. The ignition gas loop and the main gas loop are structurally arranged independently, wherein the ignition gas loop is only used for ignition at medium and low temperature, so that the burner has the function of adjusting the flow proportion of ignition gas and main gas. The input proportion of the fuel gas for ignition is small, so that the adiabatic combustion intensity in the ignition combustion chamber can be greatly reduced, and the control of NOx is realized; the large-proportion main gas output position is positioned at the front half part of the necking section of the ignition combustion chamber, so that stable ignition of gas at medium and low temperature can be effectively ensured, and the gas at high temperature can be prevented from combusting in the ignition combustion chamber.

Description

Low NOx self-preheating high-speed burner

Technical Field

The utility model belongs to the nozzle field, concretely relates to low NOx self preheating-type high-speed nozzle.

Background

The self-preheating high-speed burner has wide application in metallurgical heat treatment furnaces. In order to produce a high-speed flame, such burners usually produce a combustion reaction with a large intensity in a small space to make the gas undergo a sharp temperature rise and volume expansion, so that the high-speed ejection of the flame is realized, but the high-intensity combustion reaction in the small space usually has a relatively high NOx emission value.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides a low NOx self-preheating high-speed burner, which can greatly reduce the high-intensity combustion in a small space under the condition of medium and low temperature, so as to realize the effective control of NOx emission on the premise of ensuring the temperature of high-speed flame; and combustion in a small space is completely avoided under the high-temperature condition, and the ultralow emission of NOx is realized.

In order to achieve the above purpose, the utility model provides a following technical scheme:

a low NOx self-preheating high-speed burner comprises a main gas channel, an ignition gas channel, an air channel and a smoke exhaust channel which are sequentially arranged from inside to outside; the ignition gas channel is provided with an ignition gas nozzle at the outlet end, the main gas channel is inserted in the ignition gas channel, the end of the gas outlet of the main gas channel extends out of the ignition gas nozzle for a certain distance, a preheater for separating the air channel from the smoke exhaust channel is axially arranged between the air channel and the smoke exhaust channel, and a guide plate closing in towards the gas spraying direction is arranged on the tail end side of the preheater; an automatic igniter, an ignition air distribution disc and a partition plate are arranged in the air channel, wherein the ignition air distribution disc is arranged in front of the ignition gas nozzle; the partition board surrounds the ignition air distribution disc and the outer side of the ignition gas spray head so as to partition and form an ignition combustion chamber at the outlet end of the air channel; the baffle plate is provided with a necking section which gradually necks down towards the gas spraying direction, and the head surface of the gas outlet end of the main gas channel extends to the necking section of the baffle plate; the inner wall surface of the partition plate and the outer peripheral surface of the ignition air distribution plate are arranged at intervals to form a secondary air channel for circulating air, and the outer wall surface of the partition plate and the inner wall surface of the preheater and the guide plate thereon are arranged at intervals to form an outer air channel for circulating air.

Furthermore, the necking section of the clapboard is in a circular truncated cone structure, and the included angle alpha between the generatrix on the clapboard and the axial line is 30-90 degrees; the throat section length of baffle is L, and the length that the gas outlet end head face of main gas passageway stretched into the throat section is D, satisfies between the two: d is more than or equal to 0 and less than or equal to 0.5L.

Further, a gap between the outer peripheral surface of the ignition gas burner and the inner wall surface of the partition plate is defined as an inner air passage, and the ratio of the effective area of the inner air passage to the effective area of the outer air passage is 1:2 to 1:1 on the same cross section.

Furthermore, at least three ignition gas nozzles are uniformly distributed on the ignition gas nozzle in the circumferential direction, and the included angle beta between the axis of each ignition gas nozzle and the axis of the ignition gas channel is 45-90 degrees.

Further, the ignition air distribution plate is arranged on the outer peripheral surface of the ignition gas channel or the outer peripheral surface of the ignition gas nozzle; at least three ignition air nozzles are uniformly arranged on the ignition air distribution plate around the circumference.

Furthermore, the ratio of the effective area of the ignition air nozzle on the ignition air distribution plate to the sectional area of the secondary air channel is 1: 2-2: 1.

Furthermore, an ignition gas automatic valve is arranged at the inlet end of the ignition gas channel, a main gas automatic valve is arranged at the inlet end of the main gas channel, and the ignition gas automatic valve and the inlet end of the main gas automatic valve are connected on a gas pipeline in parallel.

Further, a flame detector is arranged in the air channel.

The beneficial effects of the utility model reside in that:

the ignition gas loop and the main gas loop are structurally arranged independently, wherein the ignition gas loop is only used for ignition at medium and low temperature, the input proportion of the part of gas is small, and the part of gas does not need to be graded, so that the control structure is simplified, and the burner has the function of adjusting the flow proportion of ignition gas and main gas.

The ignition gas loop can be used as an ignition source, the burner is in a low NOx mode of gas staged combustion under the condition of medium and low temperature by means of the ignition function of the ignition source, the combustion amount in the ignition combustion chamber is less at the moment, the high-intensity combustion in a small space is greatly reduced, and the effective control of NOx emission is realized on the premise of ensuring the temperature of high-speed flame. When the ignition gas is turned off under the high-temperature condition, the combustion in a small space is completely avoided, the main source of NOx generation disappears, and the ultralow emission of NOx is realized.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and/or combinations particularly pointed out in the appended claims.

Drawings

For the purposes of promoting a better understanding of the objects, features and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic structural diagram of a low NOx self-preheating high-speed burner;

FIG. 2 is a top sectional view of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 1;

FIG. 4 is a schematic gas flow diagram of FIG. 3;

fig. 5 is a cross-sectional view taken along line M-M of fig. 3.

Reference numerals:

the device comprises a main gas channel 1, an ignition gas channel 2, an air channel 3, a smoke exhaust channel 4, an ignition gas nozzle 5, a preheater 6, a guide plate 7, an automatic igniter 8, an ignition air distribution plate 9, a partition plate 10, an ignition combustion chamber 11, a main combustion space 12, a flame detector 13 and a gas pipeline 14;

a necking section 1001, a cylindrical section 1002, a cylindrical section 1003, a main gas automatic valve 101, an ignition gas automatic valve 201, an ignition gas nozzle 501 and an ignition air nozzle 901;

an outside air passage H1, an inside air passage H2, a secondary air passage H3, and a primary air jet K1.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in any way limiting the scope of the invention; for a better understanding of the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc., indicating directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and are not to be construed as limiting the present invention, and those skilled in the art can understand the specific meanings of the terms according to specific situations.

Referring to fig. 1 to 5, a low NOx self-preheating high-speed burner includes a main gas channel 1, an ignition gas channel 2, an air channel 3 and a smoke exhaust channel 4 sequentially arranged from inside to outside; wherein the outlet end of the ignition gas channel 2 is provided with an ignition gas nozzle 5, the main gas channel 1 is inserted in the ignition gas channel 2, and the end of the gas outlet of the main gas channel 1 extends out of the ignition gas nozzle 2 for a certain distance. A preheater 6 for separating the air channel 3 from the smoke exhaust channel 4 is axially arranged between the air channel 3 and the smoke exhaust channel 4, and a guide plate 7 closing in towards the gas spraying direction is arranged at the tail end side of the preheater 6. An automatic igniter 8, an ignition air distribution disc 9 and a partition plate 10 are arranged in the air channel 3, wherein the ignition air distribution disc 9 is arranged in front of the ignition gas nozzle 5; a partition 10 surrounds the ignition air distribution plate 9 and the ignition gas burner 5 to divide an ignition combustion chamber 11 at the outlet end of the air channel 3. The partition plate 10 is provided with a necking section 1001 gradually necking towards the gas spraying direction, and the gas outlet end face of the main gas channel 1 extends to the necking section 1001 of the partition plate. The inner wall surface of the partition plate 10 is spaced from the outer peripheral surface of the ignition air distribution plate to form a secondary air passage H3 for the ventilation air, and the outer wall surface of the partition plate 10 is spaced from the inner wall surfaces of the preheater and the baffle plate thereon to form an outer air passage H1 for the ventilation air.

The partition board 10 in this embodiment has a necking section 1001 and two cylindrical sections 1002 and 1003, wherein the necking section 1001 is a circular truncated cone shape gradually necking toward the gas ejection direction, the two cylindrical sections are respectively disposed at two ends of the necking section, the cylindrical section 1002 is connected to the upper bottom surface of the necking section 1001, and the cylindrical section 1003 is connected to the lower bottom surface of the necking section 1001.

Specifically, the ignition gas channel 2 is located outside the main gas channel 1, an ignition gas automatic valve 201 is arranged at an inlet end (gas input end) of the ignition gas channel for controlling the input amount of ignition gas, and an ignition gas nozzle 5 is arranged at a tail end (gas outlet end) of the ignition gas channel. The main gas channel 1 passes through and penetrates out of the ignition gas nozzle 5 at the tail end of the ignition gas channel 2, and the penetration amount is based on the extension of the ignition gas nozzle to the necking section 1001 of the partition plate 10. The front end (gas input end) of the main gas channel 1 is provided with a main gas automatic valve 101 for controlling the input amount of the main gas. An ignition combustion chamber 11 is arranged outside the ignition gas nozzle 5 and is divided by a partition plate 10, the ignition combustion chamber 11 is communicated with the air channel 3 at the front end, a preheater 6 and a guide plate 7 are arranged outside the ignition combustion chamber 11, and a main combustion space 12 is arranged at the outlet of the ignition combustion chamber 11 and outside the guide plate 7.

Here, the air channel 3 and the smoke exhaust channel 4 are separated by the preheater 6, so that the recovery of the waste heat of the smoke and the high-efficiency preheating of the air can be realized. The deflector 7 arranged at the end of the preheater 6 correspondingly surrounds the outside of the ignition chamber 11 (at the end of the air channel 3). A passage formed between the outer periphery of the partition plate 10 enclosing the ignition combustion chamber 11 and the inner wall surface of the baffle plate is referred to as an outside air passage H1, and a passage between the outer periphery of the ignition gas burner 5 and the inner wall of the partition plate 10 is referred to as an inside air passage H2; the inner wall surface of the partition plate 10 and the outer peripheral surface of the ignition air distribution plate are provided with a space to form a secondary air passage H3 for circulating air, the ignition air port 901 of the ignition air distribution plate 9 is referred to as a primary air port K1, and the outer air passage H1 communicates with the main combustion space 12 behind the ignition combustion chamber 11.

In this burner, the outer air passage H1 and the ignition combustion chamber 11 are both communicated with the main combustion space 12. The air passage is partitioned by a partition plate 10 and an ignition air distribution plate 9 into an outside air passage H1, an inside air passage H2, a secondary air passage H3 and a primary air port K1, and ignition gas is introduced into an ignition combustion chamber 11 under the control of an ignition gas automatic valve 201. The preheated air partly enters the main combustion space 12 directly from the outside air passage H1, and partly enters the ignition combustion chamber 11 from the inside air passage H2 (i.e. passes through the secondary air passage H3 and the primary air nozzle K1, respectively), and starts to participate in the combustion reaction at the ignition combustion chamber.

In the present embodiment, the ignition air distribution plate 9 is disposed on the outer periphery of the ignition gas nozzle 5, and the ignition air distribution plate 9 has a plurality of uniformly arranged ignition air jet ports 901, and the ignition air jet ports 901 are primary air jet ports K1. The air flowing through the primary air nozzle K1 directly reacts with the ignition gas sprayed from the rear ignition gas nozzle 5 to form a stable ignition source, and the air flowing through the secondary air channel H3 partially reacts with the main gas in the combustion chamber under the action of the automatic igniter 8 until the main gas can smoothly react with the outside air in the main combustion space 12 after being sprayed out to ignite the combustion chamber, so as to prevent fire dropping. As a structural modification, the ignition air distribution plate 9 may also be provided on the outer peripheral surface of the ignition gas passage 2.

It should be noted that: the existence of the cylindrical section 1002 in the ignition combustion chamber 11 in the burner makes the throat section 1001 and the main combustion space 12 spaced by a certain distance, and the gas outlet end of the main gas channel 1 is located at the throat section 1001 (i.e. the throat section 1001 on the partition plate 10), so that the spraying position of the main gas is adjusted, and the spraying position of the main gas is located in the middle of the ignition combustion chamber 11 instead of the outlet or the outlet of the ignition combustion chamber 11. When the temperature of the main combustion space 12 is high, the ignition source is turned off, and combustion cannot be achieved in the ignition combustion chamber 11 under the action of the reduced section (gradually decreasing inner diameter) of the ignition combustion chamber 11, and the gas is flameless combusted outside the ignition combustion chamber 11. And when the temperature of the main combustion space 12 is lower, the staged combustion can be realized through the ignition gas loop and the main gas loop which are independently arranged.

As a further optimization of the scheme, in order to control the combustion intensity of the main fuel gas in the ignition combustion chamber 11, the included angle alpha between the generatrix on the necking section of the clapboard with the circular truncated cone structure and the axial line is 30-90 degrees; the throat section length of baffle is L, and the length that the gas outlet end head face of main gas passageway stretched into the throat section is D, satisfies between the two: d is more than or equal to 0 and less than or equal to 0.5L; the injection position of the main fuel gas is controlled and positioned at the front half part of the necking section of the ignition combustion chamber 11. On the same cross section, the ratio of the effective area H2 of the inner air channel to the effective area of the outer air channel H1 is 1:2 to 1: 1. Meanwhile, the ratio of the effective area of the ignition air nozzle on the ignition air distribution plate to the sectional area of the secondary air channel is 1: 2-2: 1.

In order to ensure the stable combustion of the ignition gas in the ignition combustion chamber 11, at least three ignition gas nozzles 501 are uniformly distributed on the ignition gas nozzle 5 around the circumferential direction, and the included angle beta between the axis of each ignition gas nozzle 501 and the axis of the ignition gas channel 2 is 45-90 degrees. Correspondingly, at least three ignition air nozzles 901 are uniformly arranged on the ignition air distribution plate 9 around the circumferential direction. Here, the ignition gas diverges at an included angle 2 β to enter the ignition combustion chamber 11, while the axial direction of the ignition air port 901 serving as the primary air port K1 is parallel to the axial line of the ignition gas passage 2 (also referred to as the burner axis) or has a tangential angle within 45 °, and the ejection direction of the part of air has no divergence angle, so that the part of air can be better mixed with the ignition gas for combustion.

In this embodiment, the ignition gas automatic valve 201 and the inlet end of the main gas automatic valve 101 are connected in parallel to the gas pipe 14. Therefore, the independent arrangement of the ignition gas loop and the main gas loop is structurally realized, wherein the ignition gas loop is only used for ignition at medium and low temperature, the input proportion of the part of gas is small, and the part of gas does not need to be classified particularly, so that the control structure is simplified, the burner has the function of adjusting the flow proportion of the ignition gas and the main gas, the small proportion of the ignition gas can greatly reduce the adiabatic combustion intensity in the ignition combustion chamber 11, the control of NOx is realized, the output position of the large proportion of the main gas is positioned in the front half part of the reduced section of the ignition combustion chamber 11, the stable ignition of the gas at the medium and low temperature can be effectively ensured, and the gas cannot be combusted in the ignition combustion chamber 11 at high temperature can be ensured.

The air passage 3 in this embodiment is further provided with a flame detector 13, and the flame detector 13 is used for checking the combustion condition in the ignition combustion chamber 11 to control the opening or closing of the ignition gas automatic valve 201 and the main gas automatic valve 101.

A control method suitable for the low-NOx self-preheating high-speed burner comprises the following steps:

(a) starting the automatic igniter 8 and supplying air into the air channel 3, then opening the ignition gas automatic valve 201 to introduce ignition gas, and igniting to enable the ignition gas and the air in the inner air channel H2 to be combusted in the ignition combustion chamber 11; during this combustion, the temperature of the gas in the ignition combustion chamber 11 rises sharply, and the volume expands, so that a high-speed gas flow is formed and ejected from the outlet (of the ignition combustion chamber 11), and the flame in the ignition combustion chamber 11 becomes a stable ignition source.

(b) After the flame in the ignition combustion chamber 11 becomes a stable ignition source (detected by the flame detector 13), the main gas automatic valve 101 is opened to introduce the main gas, and the main gas and the air in the ignition combustion chamber 11 (including the air flowing through the secondary air passage H3 and the air supplied from the outside air passage H1) sequentially undergo combustion reaction at the outlet of the ignition combustion chamber and the main combustion space 12 outside the deflector under the action of the stable flame, and the combustion reaction mainly occurs in the main combustion space 12.

When the temperature of the main combustion space outside the guide plate is lower than the set temperature, the ignition gas automatic valve 201 and the main gas automatic valve 101 are always in an open state. A small amount of ignition gas is burned in the ignition combustion chamber 11, and a large amount of main gas is burned in the main combustion space 12. The outer air flow and the inner gas flow in the main combustion space are parallel high-speed jet flows, so that the flue gas is driven to be sucked and refluxed, and the combustion intensity is low; because the ignition gas automatic valve 201 is opened, the ignition gas has an ignition function when burning, and a small amount of burning in the ignition combustion chamber 11 can cause the gas volume expansion, so as to realize high-speed flame, and under the ignition function of an ignition source, the burner has obvious flame, and the burning amount in the ignition combustion chamber 11 is less, and is approximate to a soaking combustion state. The burner at this time is in a low NOx mode of gas staged combustion.

When the temperature of the main combustion space 12 outside the guide plate 7 is greater than or equal to the set temperature, the air reaches a higher preheating temperature, the combustion reaction of the main combustion space 12 does not need to be driven by an ignition source any more, the ignition gas automatic valve 201 is closed, the main gas and the inner side air do not have a combustion condition in the ignition combustion chamber under the restriction of the necking section of the ignition combustion chamber 11, and the flame (i.e. the ignition gas combustion flame) in the ignition combustion chamber 11 disappears at this time; the combustion reaction is completely performed in the main combustion space 12 while maintaining the open state of the main gas automatic valve. The volume of the air is greatly increased after the air is preheated to a higher temperature, and a larger working condition flow rate is achieved, and the burner realizes high-speed airflow by means of a higher air ejection speed and a higher fuel gas ejection speed and parallelly ejects the airflow into the main combustion space 12; the burner enters a flameless low NOx combustion mode with high air preheating temperature, high ejection speed and strong smoke entrainment backflow. Under the condition of lacking open fire for direct ignition, the combustion intensity of the main combustion space is further weakened, and the generation of NOx in the main combustion space is reduced; the ignition combustion chamber no longer approximates adiabatic combustion, the main source of NOx production disappears, and system NOx emissions are significantly reduced.

The set point of the temperature of the main combustion space outside the baffle is determined by both the type of gas and the combustion heating mode, typically the temperature range is between 750 ℃ and 880 ℃. Specifically, the type of the gas is determined by the H contained in the gas₂And (5) dividing the content. When H is contained in the fuel gas₂When the content is not less than 10%, the fuel gas can be producer gas, coke oven gas or mixed gas of blast furnace and coke oven, and when the fuel gas is used, the set temperature is 750 ℃ if direct heating is adopted, and the set temperature is 800 ℃ if indirect heating is adopted. When H is contained in the fuel gas₂When the content is less than 10%, the fuel gas can be natural gas or liquefied petroleum gas, and when the fuel gas is used, the set temperature is 800 ℃ if direct heating is adopted, and the set temperature is 880 ℃ if indirect heating is adopted.

In order to control the combustion intensity of the main gas in the ignition combustion chamber 11, in the step (b), the ratio of the gas amount introduced into the ignition gas channel 2 to the gas amount of the main gas channel 1 is 1: 9-1: 1; the jet speed of the main fuel gas in the main fuel gas channel is not lower than 50 m/s.

In order to improve the air preheating temperature, increase the volume expansion of air, improve the working condition flow rate of air and simultaneously strengthen the flue gas heat recovery, the ratio of the air temperature passing through the preheater 6 to the flue gas temperature in the main combustion space is not less than 0.75.

The burner is suitable for direct heating and also can be used for indirect heating of I-type, P-type or double-P-type radiant tubes.

The burner can obviously reduce NOx emission under the condition of ensuring heating quality, and specific indexes are as follows by taking the application effect of the burner in a double-P radiant tube heating system as an example:

finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the scope of the claims of the present invention.

Claims (8)

1. A low NOx self-preheating high-speed burner comprises a main gas channel, an ignition gas channel, an air channel and a smoke exhaust channel which are sequentially arranged from inside to outside; the ignition gas channel is provided with an ignition gas nozzle at the outlet end, the main gas channel is inserted in the ignition gas channel, the end of the gas outlet of the main gas channel extends out of the ignition gas nozzle for a certain distance, a preheater for separating the air channel from the smoke exhaust channel is axially arranged between the air channel and the smoke exhaust channel, and a guide plate closing in towards the gas spraying direction is arranged on the tail end side of the preheater; an automatic igniter, an ignition air distribution disc and a partition plate are arranged in the air channel, wherein the ignition air distribution disc is arranged in front of the ignition gas nozzle; the method is characterized in that: the partition board surrounds the ignition air distribution disc and the outer side of the ignition gas spray head so as to partition and form an ignition combustion chamber at the outlet end of the air channel; the baffle plate is provided with a necking section which gradually necks down towards the gas spraying direction, and the head surface of the gas outlet end of the main gas channel extends to the necking section of the baffle plate; the inner wall surface of the partition plate and the outer peripheral surface of the ignition air distribution plate are arranged at intervals to form a secondary air channel for circulating air, and the outer wall surface of the partition plate and the inner wall surface of the preheater and the guide plate thereon are arranged at intervals to form an outer air channel for circulating air.

2. The low NOx self-preheating high velocity burner of claim 1, wherein: the necking section of the clapboard is in a circular truncated cone structure, and the included angle alpha between a bus on the clapboard and an axis is 30-90 degrees; the throat section length of baffle is L, and the length that the gas outlet end head face of main gas passageway stretched into the throat section is D, satisfies between the two: d is more than or equal to 0 and less than or equal to 0.5L.

3. The low NOx self-preheating high-speed burner of claim 1 or 2, wherein: a gap between the outer peripheral surface of the ignition gas nozzle and the inner wall surface of the partition plate is designated as an inner air channel, and the ratio of the effective area of the inner air channel to the effective area of the outer air channel on the same cross section is 1: 2-1: 1.

4. The low NOx self-preheating high velocity burner of claim 3, wherein: at least three ignition gas nozzles are uniformly distributed on the ignition gas nozzle in the circumferential direction, and the included angle beta between the axis of each ignition gas nozzle and the axis of the ignition gas channel is 45-90 degrees.

5. The low NOx self-preheating high velocity burner of claim 4, wherein: the ignition air distribution plate is arranged on the outer peripheral surface of the ignition gas channel or the outer peripheral surface of the ignition gas nozzle; at least three ignition air nozzles are uniformly arranged on the ignition air distribution plate around the circumference.

6. The low NOx self-preheating high velocity burner of claim 5, wherein: the ratio of the effective area of the ignition air nozzle on the ignition air distribution plate to the cross-sectional area of the secondary air channel is 1:2 to 2: 1.

7. The low NOx self-preheating high velocity burner of claim 1, wherein: the inlet end of the ignition gas channel is provided with an ignition gas automatic valve, the inlet end of the main gas channel is provided with a main gas automatic valve, and the ignition gas automatic valve and the inlet end of the main gas automatic valve are connected on a gas pipeline in parallel.

8. The low NOx self-preheating high velocity burner of claim 1, wherein: a flame detector is also arranged in the air channel.

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