CN111457376A - Low-NOx self-preheating high-speed burner and control method thereof - Google Patents
Low-NOx self-preheating high-speed burner and control method thereof Download PDFInfo
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- CN111457376A CN111457376A CN202010275446.0A CN202010275446A CN111457376A CN 111457376 A CN111457376 A CN 111457376A CN 202010275446 A CN202010275446 A CN 202010275446A CN 111457376 A CN111457376 A CN 111457376A
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- 238000000034 method Methods 0.000 title claims abstract description 11
- 239000007789 gas Substances 0.000 claims abstract description 218
- 238000002485 combustion reaction Methods 0.000 claims abstract description 125
- 239000002737 fuel gas Substances 0.000 claims abstract description 27
- 238000005507 spraying Methods 0.000 claims abstract description 7
- 238000005192 partition Methods 0.000 claims description 36
- 238000009826 distribution Methods 0.000 claims description 27
- 238000010438 heat treatment Methods 0.000 claims description 20
- 239000000779 smoke Substances 0.000 claims description 13
- 230000002093 peripheral effect Effects 0.000 claims description 11
- 239000007921 spray Substances 0.000 claims description 2
- 210000003739 neck Anatomy 0.000 claims 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000000571 coke Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/48—Nozzles
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/60—Devices for simultaneous control of gas and combustion air
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/46—Details, e.g. noise reduction means
- F23D14/66—Preheating the combustion air or gas
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
Abstract
The invention relates to a low-NOx self-preheating high-speed burner and a control method thereof, belonging to the field of burners. 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
Technical Field
The invention belongs to the field of burners, and particularly relates to a low-NOx self-preheating high-speed burner and a control method thereof.
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.
Disclosure of Invention
In view of the above, the present invention provides a low NOx self-preheating high-speed burner and a control method thereof, wherein the burner can greatly reduce high-intensity combustion in a small space under medium and low temperature conditions, so as to realize effective control of NOx emission on the premise of ensuring high-speed flame temperature; 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 purpose, the invention provides the 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 head 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 wound between the air channel and the smoke exhaust channel, and a guide plate which is closed towards the gas injection 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 closes up 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 surfaces of the preheater and the flow guide plates on the preheater are arranged at intervals to form an outer air channel for circulating air.
Furthermore, the necking section of the partition plate is of a circular truncated cone structure, the included angle α between a bus and an axis on the partition plate is 30-90 degrees, the necking section of the partition plate is L degrees, the length of the gas outlet end face of the main gas channel extending into the necking section is D, and 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 on the same cross section is 1:2 to 1: 1.
Furthermore, at least three ignition gas nozzles are uniformly distributed on the ignition gas nozzle in the circumferential direction, and the included angle β 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.
A control method suitable for the low-NOx self-preheating high-speed burner comprises the following steps:
(a) starting the automatic igniter and supplying air into the air channel, then opening the ignition gas automatic valve to introduce ignition gas for ignition, and igniting so that the ignition gas is combusted in the ignition combustion chamber;
(b) after the flame in the ignition combustion chamber becomes stable flame, opening a main gas automatic valve to introduce main gas, and sequentially carrying out combustion reaction on the main gas at an outlet of the ignition combustion chamber and a main combustion space outside a guide plate under the action of the stable flame;
staged combustion mode: when the temperature of the main combustion space outside the guide plate is lower than the set temperature, the ignition gas automatic valve and the main gas automatic valve are in an open state;
flameless combustion mode: when the temperature of the main combustion space positioned outside the guide plate is not lower than the set temperature, the ignition gas automatic valve is closed, and the opening state of the main gas automatic valve is kept;
the set temperature is determined by the type of gas and the combustion heating mode, and ranges from 750 ℃ to 880 ℃.
Further, in the step (b), the ratio of the gas amount introduced into the ignition gas channel to the gas amount of the main gas channel 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.
Further, the ratio of the temperature of the air passing through the preheater to the temperature of the flue gas in the main combustion space is controlled to be not less than 0.75.
Further, in the step (b), the kind of the fuel gas is determined by H contained therein2Dividing the content;
when H is contained in the fuel gas2When the content is not less than 10 percent: when the heating mode is direct heating, the set temperature is 750 ℃; when the heating mode is indirect heating of the radiant tube, the set temperature is 800 ℃;
when H is contained in the fuel gas2When the content is less than 10 percent: when the heating mode is direct heating, the set temperature is 800 ℃; when the heating mode is indirect heating of the radiant tube, the set temperature is 880 ℃.
The invention has the beneficial effects 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 a medium-low temperature, the input proportion of the part of gas is small, and the part of gas does not need to be classified, 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 combinations particularly pointed out hereinafter.
Drawings
For purposes of promoting a better understanding of the objects, aspects 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 disc 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 embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope 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 in a schematic way, 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 the drawings in which there is no intention to limit the invention thereto; to better illustrate 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 components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art 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 outside of the ignition gas burner 5 to partition an ignition combustion chamber 11 at the outlet end of the air passage 3. The partition plate 10 has a necking section 1001 which gradually narrows toward the gas ejection 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 provided at an inlet end (gas input end) thereof to control the input amount of the ignition gas, and an ignition gas nozzle 5 is provided at a tail end (gas output end) thereof. 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 the partition plate 10 and the 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 the ignition combustion chamber 11 under the control of the 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 in 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 of the ignition combustion chamber, so as to prevent fire escape. 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 enables the necking section 1001 to be separated from the main combustion space 12 by a certain distance, and the end of the gas outlet of the main gas channel 1 is positioned at the necking section 1001 (namely, the necking 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 positioned 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 the ignition combustion chamber 11 cannot burn due to the effect of the reduced section (gradually decreasing inner diameter) of the ignition combustion chamber 11, and the gas burns flameless outside the ignition combustion chamber 11. When the temperature of the main combustion space 12 is low, staged combustion can be realized by 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 α between a bus on a necking section of the partition plate of the circular truncated cone structure and an axis is 30-90 degrees, the necking section of the partition plate is L in length, the length of a fuel gas outlet end face of the main fuel gas channel extending into the necking section is D, the D is more than or equal to 0 and less than or equal to 0.5L, the ejection position of the main fuel gas is controlled and positioned in the front half part of the necking section of the ignition combustion chamber 11, the ratio of the effective area H2 of an inner air channel to the effective area H1 of an outer air channel is 1: 2-1: 1 on the same cross section, and the ratio of the effective area of an ignition air nozzle on the ignition air distribution plate to the cross section of a secondary air channel is 1: 2-2: 1.
In order to ensure 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 circumference, an included angle β between the axis of each ignition gas nozzle 501 and the axis of the ignition gas channel 2 is 45-90 degrees, and correspondingly, at least three ignition air nozzles 901 are uniformly arranged on the ignition air distribution plate 9 around the circumference, the ignition gas is diffused into the ignition combustion chamber 11 at an included angle of 2 β, the axial direction of the ignition air nozzle 901 serving as a primary air nozzle K1 is parallel to the axis of the ignition gas channel 2 (also serving as a nozzle axis) or has a tangential angle within 45 degrees, and the ejection direction of part of the air has no diffusion angle, so that the part of the air can be better mixed and combusted with the ignition gas.
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 realized structurally, wherein the ignition gas loop is only used for ignition at medium and low temperatures, 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 medium and low temperatures 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 baffle plate 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, under the ignition function of an ignition source, the burner has obvious flame, the burning amount in the ignition combustion chamber 11 is less, and the state is similar 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 carried out entirely 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 flame direct contact point combustion, 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 (4) 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 fuel gas in the ignition combustion chamber 11, in the step (b), the ratio of the fuel gas amount introduced into the ignition fuel gas channel 2 to the fuel gas amount of the main fuel 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 heat recovery of flue gas, 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 for illustrating the technical solutions of the present invention and not for limiting, 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 on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all that should be covered by the claims of the present invention.
Claims (10)
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-speed burner as claimed in claim 1, wherein the necking section of the partition plate is of a circular truncated cone structure, an included angle α between a generatrix on the partition plate and an axis is 30-90 degrees, the length of the necking section of the partition plate is L, the length of the gas outlet end face of the main gas channel extending into the necking section is D, and 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-speed burner of claim 3, wherein at least three ignition gas nozzles are uniformly distributed on the ignition gas nozzle around the circumference, and the included angle β 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.
9. A control method suitable for the low-NOx self-preheating high-speed burner as claimed in any one of claims 4 to 8, characterized by comprising the following steps:
(a) starting the automatic igniter and supplying air into the air channel, then opening the ignition gas automatic valve, introducing ignition gas and igniting to enable the ignition gas to burn in the ignition combustion chamber;
(b) after the flame in the ignition combustion chamber becomes stable flame, opening a main gas automatic valve to introduce main gas, and sequentially carrying out combustion reaction on the main gas at an outlet of the ignition combustion chamber and a main combustion space outside a guide plate under the action of the stable flame;
staged combustion mode: when the temperature of the main combustion space positioned outside the guide plate is lower than the set temperature, the ignition gas automatic valve and the main gas automatic valve are in an open state;
flameless combustion mode: when the temperature of the main combustion space positioned outside the guide plate is not lower than the set temperature, the ignition gas automatic valve is closed, and the opening state of the main gas automatic valve is kept;
the set temperature is determined by the type of gas and the combustion heating mode, and ranges from 750 ℃ to 880 ℃.
10. The method of claim 9, wherein the method comprises: in the step (b), the ratio of the gas amount introduced into the ignition gas channel to the gas amount of the main gas channel 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.
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| CN202010275446.0A CN111457376A (en) | 2020-04-09 | 2020-04-09 | Low-NOx self-preheating high-speed burner and control method thereof |
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| CN202010275446.0A CN111457376A (en) | 2020-04-09 | 2020-04-09 | Low-NOx self-preheating high-speed burner and control method thereof |
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Cited By (1)
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| CN111928243A (en) * | 2020-09-07 | 2020-11-13 | 沈阳锐焰科技有限公司 | Self-preheating low-nitrogen combustor and use method thereof |
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