CN112113218B - Double-thermal-reflux partially-premixed low-nitrogen combustor and combustion method thereof - Google Patents
Double-thermal-reflux partially-premixed low-nitrogen combustor and combustion method thereof Download PDFInfo
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- CN112113218B CN112113218B CN202011184762.3A CN202011184762A CN112113218B CN 112113218 B CN112113218 B CN 112113218B CN 202011184762 A CN202011184762 A CN 202011184762A CN 112113218 B CN112113218 B CN 112113218B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 28
- 238000010992 reflux Methods 0.000 title claims abstract description 10
- 238000009841 combustion method Methods 0.000 title claims abstract description 9
- 239000000446 fuel Substances 0.000 claims abstract description 138
- 238000002485 combustion reaction Methods 0.000 claims abstract description 53
- 238000002347 injection Methods 0.000 claims abstract description 49
- 239000007924 injection Substances 0.000 claims abstract description 49
- 239000002737 fuel gas Substances 0.000 claims description 52
- 239000007789 gas Substances 0.000 claims description 28
- 239000011148 porous material Substances 0.000 claims description 20
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 14
- 239000003546 flue gas Substances 0.000 claims description 14
- 230000009977 dual effect Effects 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 6
- 239000006260 foam Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 5
- 230000036961 partial effect Effects 0.000 claims description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 4
- 239000001301 oxygen Substances 0.000 abstract description 4
- 229910052760 oxygen Inorganic materials 0.000 abstract description 4
- 230000009467 reduction Effects 0.000 abstract description 3
- 239000000779 smoke Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005338 heat storage Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Classifications
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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
- F23D14/12—Radiant burners
- F23D14/14—Radiant burners using screens or perforated plates
-
- 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
- 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
- F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
- F23D14/82—Preventing flashback or blowback
-
- 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 discloses a double-thermal-reflux partially-premixed low-nitrogen combustor and a combustion method thereof. The front part of the main fuel pipe is provided with an injection control baffle plate which surrounds the periphery of the main fuel pipe to form an injection zone. The front end of the main fuel pipe outlet is provided with an injection pipe, and an injection pipe outlet extends out of the injection zone. The front part of the guide cylinder is provided with a duty fuel premixing cavity, and a main air channel is formed between the duty fuel premixing cavity and the guide cylinder. The front part of the on-duty fuel pipe is provided with a plurality of on-duty fuel nozzles, and the on-duty fuel nozzles extend into the on-duty fuel premixing cavity. The on-duty fuel premixing cavity is internally provided with a cyclone disc, a first porous medium unit and a second porous medium unit from back to front, and the porosity of the first porous medium unit is smaller than that of the second porous medium unit. The invention has the advantages of good adaptability and stable combustion, solves the contradiction between the great reduction of the oxygen content in the low NO x combustion and the combustion stability, and can realize the low NO x emission.
Description
Technical Field
The invention relates to a double-heat backflow part premixing low-nitrogen combustor and a combustion method thereof, and belongs to the technical field of combustion.
Background
With the increasing environmental standards, there is a need to further reduce NOx emissions to 15mg/Nm 3 or even near zero emissions. The NOx generated by the combustion of gases such as natural gas is mainly of a thermal type and a rapid type, wherein the thermal type NOx accounts for 95%, and the inhibition of the thermal type NOx generation is a main way for reducing the NOx.
Currently, in various low-nitrogen combustion technologies, the main measures are to reduce the flame combustion temperature, disperse the high temperature region and reduce the residence time of the high temperature region. Natural gas low nitrogen combustion techniques include flue gas recirculation, flue gas internal circulation, premixed lean combustion techniques, and the like. In the flue gas recirculation technology, in order to stabilize flame, a fuel-rich combustion and backflow area is mainly adopted to improve the stability of the on-duty flame, so that local high temperature and local high NOx generation rate are brought, the improvement of the on-duty flame stability and the reduction of NOx are contradictory, and the method is a main technical difficulty for further reducing NOx.
The internal circulation mode of the flue gas is formed by air or fuel jet, and particularly the fuel jet realizes the mixing of the fuel before ignition and high-temperature flue gas, can form local flameless combustion, and has remarkable effects on ignition stability and inhibiting NOx generation. However, achieving the above combustion characteristics requires the formation of stable jet entrainment, mixing, and ignition sites. The chinese patent document CN2078153 proposes that the venturi principle is adopted to obtain entrainment of fuel jet, this mode is easily affected by the large flow field in the furnace, the entrainment back pressure at the root of the burner oscillates along with the fluctuation of the backflow area, resulting in the abrupt change of entrainment amount, causing severe pulsation of combustion and even flameout. In order to solve the problems, the Chinese patent document CN 108738333 discloses that a jet injection area is buried in the wall surface of a hearth, but the problems of overtemperature of the outer wall of the hearth, difficult arrangement and the like are caused.
Disclosure of Invention
The invention aims to provide a double-heat-reflux partially-premixed low-nitrogen burner and a low-nitrogen combustion method, which utilize the heat of circulating reflux in flue gas to heat mixed fuel gas and oxidant, reduce nitrogen oxides and stably burn slow fire. The injection baffle is utilized to maintain the pressure stability of the high-temperature flue gas, and porous medium is adopted to burn to form a lean fuel on duty flame, so that the on duty flame stability is improved, and the NO x emission is less than 15mg/Nm 3(@3.5％O2.
The invention is realized by the following technical scheme:
The double-heat backflow part premixing low-nitrogen combustor can be arranged in a combustion chamber and comprises a guide cylinder and a fuel main pipe arranged in the center of the guide cylinder, wherein the front end of the fuel main pipe comprises an on-duty fuel pipe arranged in the center of the guide cylinder and a plurality of main fuel pipes uniformly arranged on the periphery of the guide cylinder; the front part of the main fuel pipe is provided with an injection control baffle, and the injection control baffle surrounds the periphery of the main fuel pipe to form an injection zone; the main fuel pipe outlet is a tapered opening, the front end of the tapered opening is provided with an injection pipe, and the injection pipe outlet extends out of the injection zone; the front part of the guide cylinder is provided with an on-duty fuel premix chamber, and a main air channel is formed between the outer wall of the on-duty fuel premix chamber and the inner wall of the guide cylinder; the top of the front end of the on-duty fuel pipe is closed, a plurality of on-duty fuel nozzles are uniformly arranged on the wall surface of the front part of the on-duty fuel pipe along the circumference, and the front part of the on-duty fuel pipe provided with the on-duty fuel nozzles extends into the on-duty fuel premixing cavity; a cyclone disc and a porous medium unit are arranged in the duty fuel premix chamber from back to front, and the porous medium unit is arranged at the front end of the duty fuel premix chamber to form a duty flame combustion carrier; the porous medium units comprise a first porous medium unit and a second porous medium unit which are sequentially arranged from back to front, and the porosity of the first porous medium unit is smaller than that of the second porous medium unit.
In the technical scheme, the main air channel is arranged according to the air flow rate of 30-50 m/s.
In the technical scheme, the cyclone disc is arranged according to the cyclone number greater than 0.35.
In the above technical scheme, the middle part of the duty fuel premixing cavity is also provided with a flow equalizing pore plate, the flow equalizing pore plate is arranged between the cyclone disc and the first porous medium unit, and the aperture ratio of the flow equalizing pore plate is 0.1-0.3.
In the above technical scheme, the first porous medium unit and the second porous medium unit are both made of silicon carbide foam ceramic or aluminum oxide foam ceramic; and the porosity of the first porous medium unit is more than or equal to 0.8, and the pore density is 20-40PPI; the second porous medium unit has a porosity of 0.85 or more and a pore density of 10-20PPI.
In the technical scheme, the on-duty fuel nozzle is axially provided with a front group and a rear group along the on-duty fuel pipe to form a front group and a rear group of on-duty fuel nozzle groups, and the swirl disk is arranged between the front group and the rear group of on-duty fuel nozzle groups; each group of duty fuel nozzle groups comprises a plurality of duty fuel nozzles which are uniformly arranged along the circumference.
A dual hot reflux partially premixed low nitrogen combustion method comprising:
enabling the fuel gas to enter a fuel main pipe, and then respectively splitting the fuel gas into duty fuel gas and main fuel gas through a duty fuel pipe and a main fuel pipe;
enabling air to enter the combustor through the guide cylinder, enabling a part of air to enter the duty fuel premixing cavity to serve as duty flame auxiliary fuel gas, enabling the rest of air to serve as main auxiliary fuel gas to be ejected into the combustion chamber at high speed through a main air channel between the duty fuel premixing cavity and the outer wall and the inner wall of the guide cylinder, and forming a entrainment backflow area;
Spraying the on-duty fuel gas into the on-duty fuel premixing cavity in a jet mode through an on-duty fuel pipe nozzle, mixing the on-duty fuel gas with on-duty flame combustion-supporting gas under the swirling action of a swirling tray to form premixed gas, homogenizing the premixed gas through a flow equalizing pore plate to ensure that the velocity of the premixed gas is uniformly distributed, preheating the premixed gas in a first porous medium unit, and finally forming lean-burn premixed on-duty flame in a second porous medium unit and an outlet face of the second porous medium unit;
The main fuel gas is sprayed out from the tapered opening through the main fuel pipe to form high-speed jet flow, high-temperature smoke in the injection baffle is sucked, mixed with fuel in the injection pipe, sprayed into the combustion chamber under the steady flow action of the injection pipe and the injection control baffle, mixed with the main combustion-supporting gas and ignited by on-duty flame to generate high-temperature smoke;
The main combustion-supporting gas continuously enters the combustion chamber through the main air channel at a high speed to form a large backflow area, high-temperature flue gas in the entrainment combustion chamber flows back to the vicinity of the burner, the mixing of the high-temperature flue gas and the main fuel gas is promoted, the temperature of the main fuel gas and the main auxiliary fuel gas mixed later are improved by the heat of backflow, the oxygen partial pressure of the high-temperature mixed gas is reduced, the continuously-entering main fuel gas high-speed jet flow is rapidly mixed, and meanwhile, the low-nitrogen combustion is realized under the stable combustion effect of the on-duty flame.
In the technical scheme, the on-duty fuel gas quantity is 5% -15% of the fuel gas quantity.
In the technical scheme, the equivalent ratio of the on-duty fuel gas to the on-duty flame fuel gas in the on-duty fuel premixing cavity is less than 1.
The invention has the following advantages and beneficial effects:
The on-duty flame adopts a porous medium combustion technology, and the stable combustion range of the on-duty flame is expanded through the high heat storage and high radiation capacity of the porous medium skeleton, so that the adaptation and combustion stability of the whole burner can be ensured; the porous medium lean combustion is adopted, so that low-nitrogen combustion of on-duty flame can be realized; the application of two porous medium units with different porosities can avoid tempering; the main combustion air is sprayed into the combustion chamber at a high speed, a large backflow area is formed in the combustion chamber, so that flue gas in the combustion chamber flows back to the vicinity of the burner, and the main fuel is rapidly mixed with the main fuel through high-speed injection of the main fuel, so that flameless combustion of the main fuel is realized, and the generation of NO X is greatly reduced; the injection control baffle controls the injection of the main fuel, reduces the influence of the fluctuation of the smoke environment in the combustion chamber on the injection efficiency of the main fuel, and realizes the double-thermal reflux heating and the reduction of the oxygen partial pressure before the main fuel gas and the main combustion-supporting gas are mixed, thereby ensuring the stable and ultralow nitrogen combustion.
Drawings
Fig. 1 is a schematic view of a circulating nitrogen burner according to the present invention.
Fig. 2 is a schematic structural diagram of a cyclone disk according to the present invention.
In the figure: 1-a guide cylinder; 2-main fuel pipe; 201-a tapered mouth; 202-ejector tube; 3-injecting a control baffle; 4-duty fuel pipe; 401-duty fuel nozzle; 5-a swirl disk; 6-duty fuel premixing cavity; 7-a flow equalizing pore plate; 8-a first porous media element; 9-a second porous media element; 10-fuel mother pipe; 11-feed tube.
Detailed Description
The following describes the embodiments and working processes of the present invention with reference to the accompanying drawings.
The terms of directions such as up, down, left, right, front and rear in the present document are established based on the positional relationship shown in the drawings. The drawings are different, and the corresponding positional relationship may be changed, so that the scope of protection cannot be understood.
As shown in fig. 1, a dual hot return partially premixed low nitrogen burner has an outlet disposed in a combustion chamber, including a guide cylinder 1 and a fuel header 10 disposed at the center of the guide cylinder 1. The fuel mother pipe is provided with a feed pipe 11, and the feed pipe 11 is arranged specifically according to the use condition, and can be arranged on the side surface of the burner as shown in fig. 1 or can be arranged outside the bottom of the burner.
And the fuel flow direction is forward and backward. The front end of the fuel pipe 10 comprises an on-duty fuel pipe 4 arranged in the center of the guide cylinder 1 and a plurality of main fuel pipes 2 uniformly arranged on the periphery of the guide cylinder 1. The fuel gas is made to enter the fuel pipe 10 and then split into an on-duty fuel gas and a main fuel gas through the on-duty fuel pipe 4 and the main fuel pipe 2, respectively.
The front part of the main fuel pipe 2 is provided with an injection control baffle plate 3, and the injection control baffle plate 3 surrounds the periphery of the main fuel pipe 2 to form an injection zone. The injection control baffle 3 enables the injection zone pressure to be kept relatively stable, so that the main fuel injection quantity is stable. The outlet of the main fuel pipe 2 is a tapered port 201, the front end of the tapered port 201 is provided with an injection pipe 202, and the outlet of the injection pipe 202 extends out of the injection zone. The taper port 201 and the injection pipe 202 are generally coaxially arranged, and the inner diameter of the injection pipe 202 is larger than the inner diameter of the outlet of the taper port 201, so that the main fuel gas sprayed out of the taper port can completely pass through the injection pipe 202 in a high-speed jet flow.
The front part of the guide cylinder 1 is provided with an on-duty fuel premix chamber 6, and a main air channel is formed between the outer wall of the on-duty fuel premix chamber 6 and the inner wall of the guide cylinder 1. The main air channel is arranged at an air flow rate of 30-50 m/s. The air enters the burner through the guide cylinder 1, a part of the air enters the duty fuel premixing cavity 6 to be used as duty flame auxiliary fuel gas, and the rest of the air is used as main auxiliary fuel gas to be injected into the combustion chamber at high speed through a main air channel between the duty fuel premixing cavity 6 and the outer wall and the inner wall of the guide cylinder 1 to form a entrainment backflow area.
The top of the front end of the on-duty fuel pipe 4 is closed, a plurality of on-duty fuel nozzles 401 are uniformly arranged on the wall surface of the front part of the on-duty fuel pipe 4 along the circumference, and the front part of the on-duty fuel pipe provided with the on-duty fuel nozzles stretches into the on-duty fuel premixing cavity 6. The back of the on-duty fuel premixing cavity 6 is provided with a cyclone disk 5, so that the on-duty fuel gas is sprayed into the on-duty fuel premixing cavity 6 in a jet mode through an on-duty fuel pipe nozzle 401, and is mixed with the on-duty flame combustion-supporting gas under the cyclone action of the cyclone disk 5to form premixed gas. As an optimized technical scheme, the on-duty fuel nozzles 401 are axially arranged along the on-duty fuel pipe 4 to form front and rear on-duty fuel nozzle groups each comprising a plurality of on-duty fuel nozzles, and the swirl disk 5 is arranged between the front and rear on-duty fuel nozzle groups, so that on-duty fuel and on-duty flame auxiliary fuel gas are rapidly mixed.
The swirl disk 5 comprises a number of swirl vanes, as shown in fig. 2, the swirl number of the swirl disk is:
Wherein R 1 is the inner radius of the swirl vane, R 2 is the outer radius of the swirl vane, and beta is the included angle between the swirl vane and the axial direction. The swirl disk 5 is arranged here with a swirl number of greater than 0.35.
The middle part of the duty fuel premixing cavity 6 is also provided with a flow equalizing pore plate 7, the flow equalizing pore plate 7 is arranged between the cyclone disc 5 and the first porous medium unit 8, and the aperture ratio of the flow equalizing pore plate 7 is 0.1-0.3. The speed distribution of the premixed gas in the premixing cavity 6 is uniform under the flow equalizing effect of the flow equalizing pore plate 7.
The front end of the duty fuel premixing cavity 6 is provided with a duty flame combustion carrier formed by a porous medium unit. The porous medium units comprise a first porous medium unit 8 and a second porous medium unit 9 which are sequentially arranged from back to front, and the first porous medium unit 8 and the second porous medium unit 9 are made of silicon carbide foam ceramics or aluminum oxide foam ceramics; and the porosity of the first porous medium unit 8 is more than or equal to 0.8, and the pore density is 20-40PPI; the second porous medium unit 9 has a porosity of 0.85 or more and a pore density of 10-20PPI. And the porosity of the first porous medium unit 8 is smaller than the porosity of the second porous medium unit 9.
The porous medium unit satisfies: the first porous medium unit Pe is less than 65, and the second porous medium unit Pe is more than or equal to 65, so that the duty flame is stabilized between the second porous medium unit or the first porous medium and the second porous medium, and quenched in the first porous medium, and the duty fuel gas is prevented from flowing back to form tempering. Pe (peclet number) is:
Wherein S L is the laminar flame speed, d m is the characteristic pore diameter of the porous medium, c p is the specific heat capacity of the premixed gas, ρ g is the density of the premixed gas, and λ g is the thermal conductivity of the premixed gas.
The premixed gas is uniformly distributed in speed through the flow equalizing pore plate 7, then preheated and ignited in the first porous medium unit 8, and finally forms on-duty flame in the second porous medium unit 9 and the outlet thereof, and the on-duty flame can be formed between the first porous medium unit and the second porous medium unit.
The main fuel gas is sprayed out from the tapered port 201 through the main fuel pipe 2 to form high-speed jet flow, high-temperature smoke in the injection control baffle 3 is sucked, mixed with fuel in the injection pipe 202, enters the combustion chamber under the steady flow action of the injection pipe 202 and the injection control baffle 3, is mixed with the main combustion-supporting gas and is ignited by on-duty flame to generate high-temperature smoke. The main combustion-supporting gas continuously enters the combustion chamber through the main air channel at a high speed to form a large backflow area, high-temperature flue gas in the entrainment combustion chamber flows back to the vicinity of the burner, the mixing of the high-temperature flue gas and the main fuel gas is promoted, the temperature of the main fuel gas and the main combustion-supporting gas mixed later are increased by the backflow heat, and the oxygen partial pressure of the high-temperature mixed gas is reduced. Meanwhile, the high-speed air flow formed by the main fuel gas sprayed out of the tapered opening 201 can jet the smoke, so that the rapid mixing of the high-temperature smoke, the smoke mixed fuel and the main fuel gas is realized, and the low-nitrogen flameless combustion is realized. The main fuel pipe necking 201 is positioned in the injection control baffle plate, so that the main fuel gas injection smoke is not influenced by the smoke environment in the combustion chamber, and the injection efficiency is ensured. In addition, the backflow area in the combustion chamber compresses backflow streamline near the burner nozzle to be converged near the center, so that a virtual stagnation flame stabilizing surface of the on-duty flame is formed, and meanwhile combustion under the stable combustion effect of the on-duty flame is realized. The continuously entering main fuel gas high-speed jet flow is quickly and uniformly mixed, and low-nitrogen combustion is realized under the stable combustion effect of the duty flame.
The fuel gas quantity on duty is 5% -15% of the fuel gas quantity. The equivalent ratio of the on-duty fuel gas to the on-duty flame auxiliary fuel gas in the on-duty fuel premixing cavity 6 is less than 1 and is usually 0.6-0.95. The on-duty flame is in a lean fuel combustion state, so that the on-duty fuel is ensured to be fully and stably combusted.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. The double-heat backflow part premixing low-nitrogen combustor is capable of being arranged in a combustion chamber and is characterized by comprising a guide cylinder (1) and a fuel mother pipe (10) arranged in the center of the guide cylinder (1), wherein the front end of the fuel mother pipe (10) comprises a duty fuel pipe (4) arranged in the center of the guide cylinder (1) and a plurality of main fuel pipes (2) uniformly arranged on the periphery of the guide cylinder (1); an injection control baffle (3) is arranged at the front part of the main fuel pipe (2), and the injection control baffle (3) surrounds the periphery of the main fuel pipe (2) to form an injection zone; an injection pipe (202) is arranged at the front end of the outlet of the main fuel pipe (2), a tapered opening (201) is selected as the outlet of the main fuel pipe (2), the injection pipe (202) is arranged at the front end of the tapered opening (201), and the outlet of the injection pipe (202) extends out of the injection area; the front part of the guide cylinder (1) is provided with an on-duty fuel premixing cavity (6), and a main air channel is formed between the outer wall of the on-duty fuel premixing cavity (6) and the inner wall of the guide cylinder (1); the top of the front end of the on-duty fuel pipe (4) is closed, a plurality of on-duty fuel nozzles (401) are arranged on the wall surface of the front part of the on-duty fuel pipe (4), and the front part of the on-duty fuel pipe provided with the on-duty fuel nozzles extends into the on-duty fuel premixing cavity (6); a cyclone disc (5) and a porous medium unit are arranged in the duty fuel premix chamber (6) from back to front, and the porous medium unit is arranged at the front end of the duty fuel premix chamber (6) to form a duty flame combustion carrier; the porous medium units comprise a first porous medium unit (8) and a second porous medium unit (9) which are sequentially arranged from back to front, and the porosity of the first porous medium unit (8) is smaller than that of the second porous medium unit (9); the middle part of the duty fuel premixing cavity (6) is also provided with a flow equalizing pore plate (7), and the flow equalizing pore plate (7) is arranged between the cyclone disc (5) and the first porous medium unit (8).
2. The dual hot return partially premixed low nitrogen burner of claim 1 wherein said primary air passage is provided at an air flow rate of 30 to 50 m/s.
3. Double hot reflow partial premix low nitrogen burner in accordance with claim 1, wherein the swirl disk (5) is arranged with a swirl number of more than 0.35.
4. The double hot reflux partially premixed low nitrogen burner according to claim 1, wherein the aperture ratio of the flow equalizing orifice plate (7) is 0.1-0.3.
5. The dual thermal reflow partial premix low nitrogen burner in accordance with claim 1, wherein the first porous media unit (8) and the second porous media unit (9) are both silicon carbide foam ceramic or aluminum oxide foam ceramic; and the porosity of the first porous medium unit (8) is more than or equal to 0.8, and the pore density is 20-40PPI; the second porous medium unit (9) has a porosity of 0.85 or more and a pore density of 10-20PPI.
6. The dual hot return partially premixed low nitrogen burner of claim 1, wherein the duty fuel nozzle (401) is axially disposed along the duty fuel tube (4) in two front and rear groups forming two front and rear groups of duty fuel nozzle groups, and the swirl disk (5) is disposed between the two front and rear groups of duty fuel nozzle groups; each group of shift fuel nozzle groups comprises a plurality of shift fuel nozzles (401) which are uniformly arranged along the circumference.
7. A dual hot reflux partially premixed low nitrogen combustion method using the dual hot reflux partially premixed low nitrogen burner of any one of claims 1 to 6, the method comprising:
enabling fuel gas to enter a fuel main pipe (10), and then respectively splitting the fuel gas into duty fuel gas and main fuel gas through a duty fuel pipe (4) and a main fuel pipe (2);
enabling air to enter the burner through the guide cylinder (1), enabling a part of air to enter the duty fuel premixing cavity (6) to serve as duty flame auxiliary fuel gas, enabling the rest of air to serve as main auxiliary fuel gas to be ejected into the combustion chamber at a high speed through a main air channel between the duty fuel premixing cavity (6) and the outer wall and the inner wall of the guide cylinder (1) and forming a entrainment backflow area;
Spraying the on-duty fuel gas into an on-duty fuel premixing cavity (6) through an on-duty fuel pipe nozzle (401) in a jet flow mode, mixing the on-duty fuel gas with on-duty flame combustion-supporting gas under the swirling action of a swirling disc (5) to form premixed gas, homogenizing the premixed gas through a flow equalizing pore plate (7) to enable the velocity of the premixed gas to be uniformly distributed, preheating the premixed gas in a first porous medium unit (8) and finally forming on-duty flame in a second porous medium unit (9) and an outlet face of the second porous medium unit;
the main fuel gas is sprayed out from a tapered opening (201) through a main fuel pipe (2) to form high-speed jet flow, and enters a combustion chamber under the steady flow action of an injection pipe (202) and an injection control baffle (3), is mixed with the main combustion-supporting gas and is ignited to generate high-temperature flue gas;
The main combustion-supporting gas is continuously injected into the combustion chamber through the main air channel at a high speed, and the formed entrainment backflow area brings the heat of the high-temperature flue gas into the area near the burner nozzle, so that the entrainment backflow area is quickly mixed with the continuously-entering main fuel gas high-speed jet flow, the main fuel gas is heated, and stable low-nitrogen combustion is realized.
8. The low nitrogen combustion method of claim 7, wherein the on-duty fuel amount is 5% -15% of the fuel amount.
9. The low nitrogen combustion method according to claim 7, wherein the equivalent ratio of on-duty fuel gas to on-duty flame co-fuel gas in the on-duty fuel premix chamber (6) is less than 1.
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