CN114738755B - Coal-ammonia mixed combustion burner for coal-fired boiler with four tangential corners - Google Patents

Coal-ammonia mixed combustion burner for coal-fired boiler with four tangential corners Download PDF

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CN114738755B
CN114738755B CN202210461572.4A CN202210461572A CN114738755B CN 114738755 B CN114738755 B CN 114738755B CN 202210461572 A CN202210461572 A CN 202210461572A CN 114738755 B CN114738755 B CN 114738755B
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coal
air
ammonia
sleeve
fired boiler
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CN114738755A (en
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谭厚章
周上坤
崔保崇
杨文俊
王学斌
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Xian Jiaotong University
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Xian Jiaotong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D17/00—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel
    • F23D17/005—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel gaseous or pulverulent fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C1/00—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air
    • F23C1/12—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air gaseous and pulverulent fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
    • F23K5/00—Feeding or distributing other fuel to combustion apparatus
    • F23K5/002—Gaseous fuel
    • F23K5/007—Details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L1/00—Passages or apertures for delivering primary air for combustion 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2204/00—Burners adapted for simultaneous or alternative combustion having more than one fuel supply
    • F23D2204/20—Burners adapted for simultaneous or alternative combustion having more than one fuel supply gaseous and pulverulent fuel
    • 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 belongs to the field of combustion equipment and technology, and discloses a coal-ammonia mixed combustion burner for a coal-fired boiler with four tangential corners, which comprises a central air pipe, wherein a primary air sleeve and a peripheral air sleeve are sequentially sleeved outside the central air pipe; the central air pipe is internally provided with a bluff body support column, the bluff body support column is provided with a plurality of axial rotational flow blades, the air outlet end of the central air pipe is provided with a stable combustion bluff body, the air inlet end of the primary air sleeve is provided with a plurality of ammonia gas spray pipes, a guide plate and a primary air support plate are fixedly arranged inside the primary air sleeve, the guide plate is axially arranged along the central air pipe, and the primary air sleeve is connected with the central air pipe through the primary air support plate; the air inlet end of the perimeter air sleeve is provided with a perimeter air volute, a perimeter air supporting plate is arranged inside the perimeter air sleeve, and the perimeter air sleeve is connected with the primary air sleeve through the perimeter air supporting plate. The coal-ammonia mixed combustion method is suitable for coal-ammonia mixed combustion, can improve the ignition stability of coal powder, can reduce the carbon content of fly ash and reduce the carbon emission of a power station boiler while not increasing the emission of nitrogen oxides.

Description

Coal-ammonia mixed combustion burner for coal-fired boiler with four tangential corners
Technical Field
The invention belongs to the field of combustion equipment and technology, and relates to a coal-ammonia mixed combustion burner for a coal-fired boiler with four tangential corners.
Background
In 2020, CO produced by fossil energy consumption worldwide 2 Emission of 348.1 hundred million tons of CO 2 The large amount of emission causes great harm to the global atmosphere and ecology. Therefore, reducing carbon emissions is a serious problem. Coal dominates energy supply structures and consumption structures, while the electric power industry is the main industry of coal consumption, so decarburization of utility boilers needs to be paid important attention.
Hydrogen and ammonia are of great interest to scholars as a "zero carbon" fuel. However, the hydrogen gas has limited its wide application due to its high transportation and storage cost and easy explosion. The storage and transportation requirements of ammonia gas are far simpler than that of hydrogen gas, the storage and transportation cost of ammonia gas is far lower than that of hydrogen gas, and the storage and transportation method has the characteristics of perfect infrastructure and the like, so that ammonia gas is widely regarded as important supplement of hydrogen energy.
The large coal-fired power plant realizes the combination of coal-fired power generation and new energy power generation through peak regulation transformation, and can ensure stable power supply. In the time period when the new energy power generation is at the wave crest, the coal-fired power plant after deep peak regulation transformation is in a low-load operation state, and can discharge less CO 2 In the time slot when the new energy power generation is in the trough, ammonia is mixed with coal for combustion according to a reasonable proportion, and CO reduction can be achieved 2 The purpose of discharging. Coal-fired power plants have had a great deal of experience and mature technology in transporting and storing ammonia due to the use of SNCR and SCR technologies, but ammonia is somewhat less reactive than other gaseous fuels and also suffers from high nitrogen oxide emissions during lean combustion. Coal is used as solid fuel, the residence time required by coke combustion is far longer than that of gas fuel, and ammonia gas is combusted in a coal-fired boiler without the situation of non-complete combustion basically, and the potential is also provided for promoting the complete combustion of coke.
Disclosure of Invention
The invention aims to overcome the defect of high emission of nitrogen oxides in the mixed combustion of ammonia and coal in the prior art, and provides a coal-ammonia mixed combustion burner for a coal-fired boiler with tangential four corners.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a coal-ammonia mixed combustion burner for a coal-fired boiler with four tangential corners comprises a central air pipe, wherein a primary air sleeve and a peripheral air sleeve are sequentially sleeved outside the central air pipe;
the central air pipe is internally provided with a bluff body support column, the bluff body support column is provided with a plurality of axial rotational flow blades, the air outlet end of the central air pipe is provided with a stable combustion bluff body, the air inlet end of the primary air sleeve is provided with a plurality of ammonia gas spray pipes, a guide plate and a primary air support plate are fixedly arranged inside the primary air sleeve, the guide plate is axially arranged along the central air pipe, and the primary air sleeve is connected with the central air pipe through the primary air support plate; the air inlet end of the perimeter air sleeve is provided with a perimeter air volute, a perimeter air supporting plate is arranged inside the perimeter air sleeve, and the perimeter air sleeve is connected with the primary air sleeve through the perimeter air supporting plate.
Optionally, the primary air supporting plate includes a plurality of transverse supporting plates and a plurality of longitudinal supporting plates, the cross section of each transverse supporting plate is rectangular, and the cross section of each longitudinal supporting plate is zigzag.
Optionally, the circumferential wind supporting plate is the same as the primary wind incoming flow direction, and an included angle between the circumferential wind supporting plate and the normal direction of the cross section of the primary wind casing is 10-30 °.
Optionally, the length L of the primary air sleeve and the diameter D of the central air pipe are equal 1 And diameter D of the stable combustion bluff body 2 The following relationship is satisfied: d 1 L = 0.2-0.35 and D 2 /D 1 ＝0.2～0.3。
Optionally, 12 to 18 axial swirl vanes are arranged on the bluff body support column.
Optionally, the axial swirl blades are connected with the bluff body support column through adjusting connecting rods, and the adjusting connecting rods are used for adjusting the size of an included angle between the axial swirl blades and the radial direction of the cross section of the primary air casing.
Optionally, an included angle between the axial swirl vane and the radial direction of the central air pipe is 30 to 60 °.
Optionally, the guide plate is connected with the primary air support plate, and the ammonia gas spray pipe is opposite to the guide plate.
Optionally, the distances between the ammonia gas spray pipe and the end faces of the left end and the right end of the parallel primary air sleeve along the airflow direction are d1 and d2 respectively, and the following relations are satisfied: d1/d2=3 to 7.
Optionally, the central air pipe is installed in the center of a primary air nozzle of the tangential firing boiler, pulverized coal and ammonia gas enter a hearth of the tangential firing boiler from the primary air nozzle of the tangential firing boiler, 20% -30% of air enters the hearth of the tangential firing boiler from the primary air nozzle of the tangential firing boiler, 50% -65% of air enters the hearth of the tangential firing boiler from a secondary air nozzle of the tangential firing boiler, and 15% -25% of air enters the hearth of the tangential firing boiler from an OFA nozzle of the tangential firing boiler; when the ammonia blending combustion ratio is lower than 25%, all ammonia is introduced from the central air pipe; when the ammonia blending proportion exceeds 25%, the ammonia with the blending proportion of 25% is introduced from the central air pipe, and the rest ammonia is introduced from the ammonia nozzle.
Compared with the prior art, the invention has the following beneficial effects:
the invention relates to a coal-ammonia co-combustion burner for a four-corner tangential coal-fired boiler, which is suitable for coal-ammonia co-combustion of the four-corner tangential coal-fired boiler, ammonia gas is introduced through a central air pipe and an ammonia gas spray pipe, ammonia gas flow and pulverized coal flow are fully mixed through an axial rotational flow blade, peripheral air is introduced through a peripheral air volute and a peripheral air sleeve to prevent flame from brushing, a nozzle is cooled to prevent the nozzle from deforming due to overhigh temperature, a guide plate is further arranged on a primary air support plate to play a role in separating light and shade, ignition of pulverized coal and ammonia is finally effectively promoted, the ignition stability of pulverized coal is further improved, the full mixing and low-nitrogen combustion of pulverized coal and ammonia gas are realized, accurate control of combustion atmosphere is realized through graded air distribution, the carbon content of fly ash is reduced while the emission of nitrogen oxides is not increased, and the carbon emission of a power station boiler is reduced.
Drawings
FIG. 1 is a schematic structural diagram of a coal-ammonia mixed combustion burner for a corner tangential coal-fired boiler according to an embodiment of the present invention;
FIG. 2 is a side view of a coal-ammonia co-fired burner for a corner tangential firing coal fired boiler according to an embodiment of the present invention;
FIG. 3 is a schematic view of the nozzle and combustion area distribution of a tangential firing coal-fired boiler according to an embodiment of the present invention.
Wherein: 1-primary air nozzle; 2-secondary air nozzle; 3-OFA nozzle; 4-1-central air duct; 4-2-ammonia gas jet pipe; 5-primary air sleeve; 6-bending the pipe section; 7-a deflector; 8-perimeter wind volute; 9-perimeter wind sleeve; 10-a bluff body support column; 11-axial swirl vanes; 12-primary air support plate; 13-perimeter wind support plate; and 14-stable combustion bluff body.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in other sequences than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
First, related terms referred to in the embodiments of the present invention are introduced:
primary air refers to a mixture of primary air and primary fuel, which includes pulverized coal and ammonia gas.
The secondary air refers to a mixture of secondary air and secondary fuel, which includes pulverized coal and ammonia gas.
Overfire air refers to tertiary air.
The invention is described in further detail below with reference to the accompanying drawings:
at present, the combustion modes of boilers used in large coal-fired power plants are mainly two types: the four corners are tangent to the circle and the front and back walls are opposite punched. The four-corner tangential firing is to inject the coal dust carried by primary air and secondary air into a hearth through an angular burner at a certain speed, form an imaginary tangential circle at the center of the hearth and generate tangential firing. Because of the full combustion and the heat load in the hearthThe advantages of uniform distribution, good coal adaptability and the like are widely applied to coal-fired power plants in China. Therefore, a four-corner tangential combustion system for coal-ammonia CO-combustion is developed by combining the combustion mode of four-corner tangential, and CO in the coal-burning process is controlled 2 The discharge of (C) has important significance.
Referring to fig. 1 to 3, in an embodiment of the present invention, a coal-ammonia mixed combustion burner for a corner tangential coal-fired boiler is provided, which is used for optimizing and transforming the corner tangential coal-fired boiler, so as to realize mixing of ammonia fuel and CO at the same time 2 Emission reduction, control of nitrogen oxide emission and reduction of carbon content in fly ash.
Specifically, the coal-ammonia mixed combustion burner for the coal-fired boiler with the four tangential corners comprises a central air pipe 4-1, and a primary air sleeve 5 and a peripheral air sleeve 9 are sequentially sleeved outside the central air pipe 4-1; a bluff body supporting column 10 is arranged in the central air pipe 4-1, a plurality of axial rotational flow blades 11 are arranged on the bluff body supporting column 10, a stable combustion bluff body 14 is arranged at the air outlet end of the central air pipe 4-1, a plurality of ammonia gas spray pipes 4-2 are arranged at the air inlet end of the primary air sleeve 5, a guide plate 7 and a primary air supporting plate 12 are fixedly arranged in the primary air sleeve 5, the guide plate 7 is axially arranged along the central air pipe 4-1, and the primary air sleeve 5 is connected with the central air pipe 4-1 through the primary air supporting plate 12; the air inlet end of the perimeter air sleeve 9 is provided with a perimeter air volute 8, a perimeter air supporting plate 13 is arranged inside the perimeter air sleeve 9, and the perimeter air sleeve 9 is connected with the primary air sleeve 5 through the perimeter air supporting plate 13.
The four-corner tangential coal-fired boiler comprises a primary air area I, a secondary air area II and an over-fire air area III in a hearth, wherein a primary air nozzle 1 is located in the primary air area I, and a secondary air nozzle 2 and an OFA nozzle (over-fire air nozzle) 3 are respectively located in the secondary air area II and the over-fire air area III. The primary air area is a strong reducing atmosphere, the secondary air area is a weak reducing atmosphere, and the OFA area is an oxidizing atmosphere. The strong reducing atmosphere can fully inhibit the conversion of volatile nitrogen in the coal powder to nitrogen oxides, the weak reducing atmosphere can fully burn out ammonia gas and inhibit the conversion of coke nitrogen to nitrogen oxides, and the oxidizing atmosphere can fully burn out coke.
In fig. 3, a, AB, B, BC, C, CD, D, and DE respectively represent different areas, wherein one letter represents a primary air area I, two letters represent a secondary air area II, and most of the primary air area I and the secondary air area II in the tetragonal tangential boiler are arranged layer by layer.
When the coal burning boiler is used, the central air pipe 4-1 is arranged at the center of a primary air nozzle 1 of a four-corner tangential coal burning boiler, a central air duct for introducing ammonia gas is arranged in the central air pipe 4-1, a stable burning bluff body 14 is arranged at the air outlet end of the central air pipe 4-1 and used for stabilizing ignition of pulverized coal, and a plurality of axial rotational flow blades 11 are arranged on a bluff body support column 10 and used for realizing mixing of the pulverized coal and the ammonia gas; a primary air channel is formed between the outer wall of the central air pipe 4-1 and the inner wall of the primary air sleeve 5 and is used for introducing primary air into the hearth, and a peripheral air channel is formed between the outer wall of the primary air sleeve 5 and the inner wall of the peripheral air sleeve 9 and is used for introducing peripheral air into the hearth. The ammonia air current is in the central zone, by buggy air current parcel, the outermost is perimeter wind air current, four corners tangent circle is buggy air current, ammonia air current, buggy air current and perimeter wind air current from center to periphery in proper order, the ammonia current passes through axial whirl blade 11 and realizes the intensive mixing with the buggy, but the ammonia does not break through buggy air current and reaches perimeter wind air current, the conversion of volatile nitrogen to nitrogen oxide in the buggy air current can be inhibited in the existence of ammonia under reducing atmosphere, perimeter wind air current can cool off the spout on the one hand, prevent that spout temperature is too high to warp, on the other hand still prevents that flame from brushing the wall and the ammonia escape from appearing.
Furthermore, the coal-ammonia mixed combustion burner for the coal-fired boiler with the tangential circles at four corners can realize the mixed combustion of ammonia gas in a large-scale coal-fired unit, realize the combination of coal-fired power generation and new energy power generation, and ensure the stable supply of electric power. In the time period when the new energy power generation is at the wave crest, the coal-fired power plant after deep peak regulation transformation is in a low-load operation state, and can discharge less CO 2 (ii) a In the time period when the new energy power generation is in the trough, ammonia gas and coal are mixed and combusted according to a proper proportion, and the carbon reduction of the coal-fired power plant is realized.
In conclusion, the coal-ammonia co-combustion burner for the four-corner tangential coal-fired boiler is suitable for coal-ammonia co-combustion of the four-corner tangential coal-fired boiler, ammonia is introduced through the central air pipe 4-1 and the ammonia nozzle 4-2, the ammonia flow is fully mixed with the pulverized coal flow through the axial swirl vanes 11, peripheral air is introduced through the peripheral air volute 8 and the peripheral air sleeve 9 to prevent flame from brushing walls, the nozzle is cooled to prevent the nozzle from deforming due to overhigh temperature, and a guide plate is further arranged on the primary air support plate to play a role in thick-thin separation, so that ignition of the pulverized coal and the ammonia is effectively promoted finally, ignition stability of the pulverized coal is improved, full mixing and low-nitrogen combustion of the pulverized coal and the ammonia are realized, accurate control of combustion atmosphere is realized through graded air distribution, the carbon content of fly ash can be reduced while emission of nitrogen oxides is not increased, and carbon emission of the boiler is reduced.
In a possible embodiment, the primary air support plate 12 includes a plurality of transverse support plates and a plurality of longitudinal support plates, the cross section of the transverse support plates is rectangular, and the cross section of the longitudinal support plates is zigzag. Specifically, in order to ensure the rigidity in the gravity direction, the transverse supporting plate can be set to be a solid rectangle, and the longitudinal supporting plate is in a sawtooth shape, so that a larger contact area with pulverized coal can be brought, and ignition of the pulverized coal is promoted.
In a possible embodiment, the circumferential wind supporting plate 13 is in the same direction as the incoming primary wind, and forms an angle of 10-30 ° with the normal direction of the section of the primary wind sleeve 5. Specifically, since the incoming flow direction of the primary air forms a certain angle with the normal direction of the primary air sleeve 5, in order to ensure that the incoming flow direction of the peripheral air is also the same as the incoming flow direction of the primary air, the peripheral air supporting plate 13 needs to form an angle of 10 to 30 degrees with the normal direction of the cross section of the primary air sleeve 5.
In a possible embodiment, the length L of the primary air sleeve 5 and the diameter D of the central air duct 4-1 1 And the diameter D of the stable combustion bluff body 14 2 The following relationship is satisfied: d 1 L = 0.2-0.35 and D 2 /D 1 ＝0.2～0.3。
Specifically, the length L of the rectangular section of the primary air sleeve 5 is fixed, the diameter D1 of the central air pipe 4-1 determines the ammonia gas injection speed, the higher ammonia gas injection speed can bring greater energy consumption, and the ammonia gas flow can break through the coal dust flow to be mixed with the peripheral air flow, and then the length L of the rectangular section of the primary air sleeve 5 is fixed, and the ammonia gas flow can break through the coal dust flow and be mixed with the peripheral air flow at the second stepThe secondary air area and the over-fire air area can be converted into nitrogen oxides, the ammonia gas cannot be mixed with the pulverized coal airflow at the excessively low ammonia gas injection speed, the effect of the ammonia gas on inhibiting the conversion of the volatile nitrogen into the nitrogen oxides is reduced, and the promotion effect of the ammonia gas on the ignition of the pulverized coal is also reduced, so that D 1 And L satisfy the following relationship D 1 L =0.2 to 0.35; the larger the diameter of the stable combustion bluff body 14 is, the more the ignition of the coal powder and the ammonia gas can be promoted, but the larger the diameter of the stable combustion bluff body 14 is, the larger the diameter of the stable combustion bluff body 14 can influence the injection speed and the flow field of the ammonia gas, and therefore, the diameter D of the stable combustion bluff body 14 2 Diameter D of central air pipe 1 The following relationship is satisfied: d 2 /D 1 ＝0.2～0.3。
In a possible embodiment, 12 to 18 axial swirl vanes 11 are arranged on the bluff body support column 10. Specifically, the momentum of the ammonia flow is large when the number of the axial swirl vanes 11 is too small, the ammonia flow is difficult to be fully mixed with the pulverized coal in the entrainment process, the resistance of the ammonia flow is increased when the number of the axial swirl vanes 11 is too large, and the plant power rate is increased, so that the number of the axial swirl vanes 11 is set to be 12-18.
In a possible embodiment, the axial swirl vanes 11 are connected with the bluff body support column 10 through adjusting connecting rods, and the adjusting connecting rods are used for adjusting the size of an included angle between the axial swirl vanes 11 and the radial direction of the central air duct 4-1.
Specifically, axial whirl blade 11 among the central tuber pipe 4-1 can bring tangential velocity for the ammonia of injection, make the ammonia entrainment buggy air current, realize the intensive mixing of ammonia with buggy and primary air, the size of ammonia stream tangential velocity has been decided to axial whirl blade 11's angle, there is the influence to the mixed degree of ammonia and buggy, the too big ammonia stream that can make pierces through the buggy air current of angle, be close to the water-cooling wall, be unfavorable for nitrogen oxide control, the angle undersize can influence the mixed effect of ammonia and buggy, in this embodiment, the radial contained angle between axial whirl blade 11 and central tuber pipe 4-1 is 30 ~ 60.
In a possible embodiment, the deflector 7 is connected with the primary air support plate 12, and the ammonia gas nozzle 4-2 is opposite to the deflector 7.
Specifically, there are two general arrangements of the flow deflector 7, one is a commonly used method, the flow deflector 7 is arranged in the elbow section 6 of the primary air sleeve 5, and extends from the outer arc surface of the elbow section 6 to the primary air nozzle direction, but this method can cause the ammonia flow to mix with the pulverized coal flow prematurely when the ammonia is sprayed out from the central air duct 4-1 and the ammonia gas spray pipe 4-2 at the same time, so that the ammonia flow can pass through the pulverized coal flow to contact with the peripheral air, resulting in excessive ammonia gas remaining in the primary air area, on one hand, reducing the inhibition of the ammonia gas on the release of volatile nitrogen in the pulverized coal, and on the other hand, promoting the conversion of the ammonia gas to nitrogen oxide in the secondary air and the OFA area. The other mode is the mode adopted in the embodiment, the guide plate 7 is connected with the primary air support plate 12, and the ammonia gas spray pipe 4-2 is opposite to the guide plate 7.
The eccentric arrangement of the guide plate 7 and the ammonia gas spray pipe 4-2 can realize the concentration separation of the pulverized coal, the distances between the ammonia gas spray pipe 4-2 and the end faces of the left end and the right end of the parallel primary air sleeve 5 in the airflow direction are d1 and d2 respectively, and in the embodiment, the two satisfy the following relations: d1/d2= 3-7, the smaller d1/d2, the more obvious the concentration separation of the coal powder, the concentration separation of the coal powder can effectively inhibit the emission of nitrogen oxides, but the abrasion of the guide plate can be caused at the same time, so that the proper arrangement position of the guide plate 7 is the key for realizing the long-term effective operation of the concentration separation of the coal powder.
In a possible implementation mode, a central air pipe 4-1 is installed in the center of a primary air nozzle 1 of a four-corner tangential coal-fired boiler, coal powder and ammonia gas enter a hearth of the four-corner tangential coal-fired boiler from the primary air nozzle 1 of the four-corner tangential coal-fired boiler, 20% -30% of air enters the hearth of the four-corner tangential coal-fired boiler from the primary air nozzle 1 of the four-corner tangential coal-fired boiler, 50% -65% of air enters the hearth of the four-corner tangential coal-fired boiler from a secondary air nozzle 2 of the four-corner tangential coal-fired boiler, 15% -25% of air enters the hearth of the four-corner tangential coal-fired boiler from an OFA nozzle 3 of the four-corner tangential coal-fired boiler, and when the mixing proportion of the ammonia gas is lower than 25%, all the ammonia gas is introduced from the central air pipe 4-1; when the ammonia gas co-combustion proportion exceeds 25%, the ammonia gas with the co-combustion proportion of 25% is introduced from the central air pipe 4-1, and the rest ammonia gas is introduced from the ammonia gas nozzle 4-2.
Specifically, two ammonia pipes may be provided, which are respectively disposed in the bent pipe section 6 and the straight pipe section of the primary air casing 5. Wherein, the ammonia pipe of the straight pipe section is an ammonia gas nozzle 4-2. When the ammonia blending combustion ratio is lower than 25%, all ammonia enters the central air duct 4-1 from the ammonia duct of the bend section 6 and then enters the hearth; when the ammonia gas blending proportion exceeds 25%, the excess ammonia gas enters the hearth from the ammonia gas nozzle 4-2 of the straight pipe section, the ammonia gas nozzle 4-2 of the straight pipe section is opposite to the guide plate 7, so that the ammonia gas enters the hearth from the dense phase region, on one hand, the conversion of volatile nitrogen in coal to nitrogen oxide is fully inhibited, and on the other hand, the ammonia gas flow cannot pass through the pulverized coal airflow, so that the emission of the nitrogen oxide is increased. No matter how the ammonia blending proportion changes, 20-30% of air can enter a hearth from a primary air area, 50-65% of air enters the hearth from a secondary air area, 15-25% of air enters the hearth from an over-fire air area, and the specific air distribution proportion of each part can be actually adjusted according to the coal quality, the ammonia blending proportion, the nitrogen oxide emission and the fly ash carbon content.
To sum up, the coal-ammonia mixed combustion burner for the coal-fired boiler with the tangential circles at four corners comprises a central air pipe 4-1, axial swirl vanes 11 and a guide plate 7. When the mixing calorific value proportion of the ammonia is lower than 25%, the ammonia completely enters the hearth through the central air pipe 4-1, and the arrangement of the axial swirl vanes 11 ensures that the ammonia has tangential velocity, thereby realizing entrainment of pulverized coal flow and full mixing with pulverized coal. The ignition of the volatiles of the pulverized coal stream promotes the ignition of ammonia, which in turn provides more "volatiles" to the ignition of the pulverized coal as a gaseous fuel, promoting the ignition combustion of the pulverized coal. The reduction effect of the ammonia gas on the nitrogen oxides formed by the volatile nitrogen is fully realized through the layered arrangement of the pulverized coal flow, the ammonia flow, the pulverized coal flow and the peripheral wind flow. When the mixing heat value proportion of the ammonia gas is higher than 25%, the redundant ammonia gas and the pulverized coal in the dense phase zone are mixed in advance, and the generation of pulverized coal nitrogen oxides in the dense phase zone can be inhibited. In comparison to pulverized coal combustion, ammonia gas burns slower than the volatile components of pulverized coal, but faster than coke. And then a large amount of oxygen in a primary air area of the coal-fired boiler with the tangential circles at four corners can be occupied by volatile matters and ammonia under strong reducing atmosphere, and the weak reducing atmosphere in a secondary air area is not suitable for the mixed combustion of a large proportion of ammonia, but is suitable for partial remaining unburnt ammonia in the primary air. Under the weak reducing atmosphere, the ammonia gas can inhibit the conversion of part of coke nitrogen to nitrogen oxides, and the ammonia gas serving as gas fuel can also assist in improving the combustion of coke, so that the carbon content of fly ash is finally reduced, and the boiler efficiency is improved.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims (9)

1. A coal-ammonia mixed combustion burner for a coal-fired boiler with four tangential corners is characterized by comprising a central air pipe (4-1), wherein a primary air sleeve (5) and a peripheral air sleeve (9) are sequentially sleeved outside the central air pipe (4-1);
a bluff body supporting column (10) is arranged in the central air pipe (4-1), a plurality of axial rotational flow blades (11) are arranged on the bluff body supporting column (10), a stable combustion bluff body (14) is arranged at the air outlet end of the central air pipe (4-1), a plurality of ammonia gas spray pipes (4-2) are arranged at the air inlet end of the primary air sleeve (5), a guide plate (7) and a primary air supporting plate (12) are fixedly arranged in the primary air sleeve (5), the guide plate (7) is axially arranged along the central air pipe (4-1), and the primary air sleeve (5) is connected with the central air pipe (4-1) through the primary air supporting plate (12); a perimeter wind volute (8) is arranged at the wind inlet end of the perimeter wind sleeve (9), a perimeter wind supporting plate (13) is arranged inside the perimeter wind sleeve (9), and the perimeter wind sleeve (9) is connected with the primary wind sleeve (5) through the perimeter wind supporting plate (13);
the guide plate (7) is connected with the primary air support plate (12), and the ammonia gas spray pipe (4-2) is opposite to the guide plate (7).
2. The coal-ammonia mixed combustion burner for a corner tangent coal-fired boiler according to claim 1, wherein the primary air support plate (12) comprises a plurality of transverse support plates and a plurality of longitudinal support plates, the cross section of each transverse support plate is rectangular, and the cross section of each longitudinal support plate is saw-toothed.
3. The coal-ammonia mixed combustion burner for a corner tangent coal-fired boiler according to claim 1, characterized in that the peripheral air supporting plate (13) has the same incoming flow direction of primary air and an included angle of 10-30 degrees with the normal direction of the primary air casing pipe section (5).
4. The coal-ammonia mixed combustion burner for a corner tangent circle coal-fired boiler according to claim 1, characterized in that the length L of the primary air sleeve (5) and the diameter D of the central air pipe (4-1) 1 And the diameter D of the stable combustion bluff body (14) 2 The following relationship is satisfied: d 1 L = 0.2-0.35 and D 2 /D 1 ＝0.2～0.3。
5. The coal-ammonia mixed combustion burner for a corner tangent circle coal-fired boiler according to claim 1, characterized in that 12-18 axial swirl blades (11) are arranged on the bluff body supporting column (10).
6. The coal-ammonia mixed combustion burner for the corner tangent circle coal-fired boiler according to claim 5, characterized in that the axial swirl blades (11) are connected with the bluff body supporting column (10) through adjusting connecting rods, and the adjusting connecting rods are used for adjusting the size of an included angle between the axial swirl blades (11) and the radial direction of the section of the primary air sleeve (5).
7. The coal-ammonia mixed combustion burner for the corner tangent circle coal-fired boiler according to claim 6, characterized in that the included angle between the axial swirl vanes (11) and the radial direction of the central air pipe (4-1) is 30-60 °.
8. The coal-ammonia mixed combustion burner for the corner tangential coal-fired boiler according to claim 1, wherein the distances between the ammonia gas nozzle (4-2) and the end surfaces of the left end and the right end of the parallel primary air sleeve (5) along the air flow direction are d1 and d2 respectively, and the following relations are satisfied: d1/d2=3 to 7.
9. The coal-ammonia mixed combustion burner for the corner-tangential coal-fired boiler according to claim 1, characterized in that a central air duct (4-1) is installed in the center of a primary air nozzle (1) of the corner-tangential coal-fired boiler, coal dust and ammonia gas enter a hearth of the corner-tangential coal-fired boiler from the primary air nozzle (1) of the corner-tangential coal-fired boiler, 20% -30% of air enters the hearth of the corner-tangential coal-fired boiler from the primary air nozzle (1) of the corner-tangential coal-fired boiler, 50% -65% of air enters the hearth of the corner-tangential coal-fired boiler from a secondary air nozzle (2) of the corner-tangential coal-fired boiler, and 15% -25% of air enters the hearth of the corner-tangential coal-fired boiler from an OFA nozzle (3) of the corner-tangential coal-fired boiler; when the ammonia blending combustion ratio is lower than 25%, all ammonia is introduced from the central air pipe (4-1); when the ammonia gas blending proportion exceeds 25 percent, the ammonia gas with the blending proportion of 25 percent is introduced from the central air pipe (4-1), and the rest ammonia gas is introduced from the ammonia gas nozzle (4-2).
CN202210461572.4A 2022-04-28 2022-04-28 Coal-ammonia mixed combustion burner for coal-fired boiler with four tangential corners Active CN114738755B (en)

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JP5832624B2 (en) * 2014-11-26 2015-12-16 三菱重工業株式会社 Oil burning burner, solid fuel burning burner unit and solid fuel burning boiler
CN105042585B (en) * 2015-09-01 2017-07-04 山东富海泰来新能源科技有限公司 Coal burner
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