CN117823893A - Graded rotational flow low-nitrogen combustor and working method thereof - Google Patents

Abstract

The invention relates to a graded rotational flow low-nitrogen combustor and a working method thereof, the graded rotational flow low-nitrogen combustor comprises a combustion shell, a distribution chamber, a conical backflow chamber, a conical expansion chamber and a conveying chamber are sequentially arranged in the longitudinal direction in the combustion shell, the distribution chamber comprises a primary feeding channel and a plurality of primary air inlet channels which are circumferentially arranged around the primary feeding channel, the primary air inlet channels are tangentially connected with one end of the conical backflow chamber, an igniter is arranged outside the conical backflow chamber, a plurality of secondary air inlet channels are further arranged in the combustion shell, one end of each secondary air inlet channel is tangentially connected with one end of the conical expansion chamber, a plurality of air inlet feeding channels are arranged on the circumferential wall outside the conveying chamber, and the air inlet feeding channels are tangentially connected with the conveying chamber. The air enters the distribution chamber, the conical reflux chamber and the conical flow expansion chamber in a tangential rotational flow mode through three different conveying paths respectively, and is fully mixed, atomized and crushed with the direct injection primary fuel and the tangential secondary fuel to form gas-liquid two-phase fuel, so that combustion stability is enhanced, and nitrogen oxide emission is reduced.

Description

Graded rotational flow low-nitrogen combustor and working method thereof

Technical Field

The invention relates to the technical field of combustors, in particular to a graded rotational flow low-nitrogen combustor and a working method thereof.

Background

Biomass is a renewable energy source with rich reserves, neutral carbon and environmental friendliness, and is rich in variety, rich in resources and high in carbon content, and is a high-quality raw material for preparing biochar. Biomass is generally converted into a biochar product by adopting a biomass pyrolysis charcoal-making technology, wherein the technology is a technology for preparing the biochar by carrying out thermal decomposition on organic materials such as biomass under the anaerobic or anoxic condition. Besides biochar, the process can also generate byproducts, namely pyrolysis volatile matters, wherein the pyrolysis volatile matters consist of pyrolysis gas and bio-oil, and the pyrolysis gas and the bio-oil are directly used as fuel for co-combustion, so that the method has the advantages of reducing emission and reducing cost. However, the pyrolysis gas has low heat value, is difficult to burn stably, and the bio-oil has high water content, poor stability, high tar viscosity and stronger acidity and corrosiveness, and can be prepared into chemicals through complex treatment. Therefore, the method is very important to the research on the utilization of pyrolysis volatile matters in the biomass pyrolysis charcoal making process.

Regarding the utilization of the pyrolysis volatiles, the treatment efficiency is improved mainly by improving the burner to directly burn the pyrolysis volatiles, but the problem in this way is that ignition is difficult, tar coking and combustion instability are caused by the low heat value and high water content of the pyrolysis volatiles. In order to solve the problem of low calorific value of pyrolysis gas, pyrolysis volatile matters are generally mixed with other fuels with high calorific value such as methane, hydrogen, ethanol and the like for combustion, and the efficiency is improved, but the burner is easily and locally overheated to generate thermal NO _X . Light biological oil is mainly burnt by adopting an atomizing nozzle structureThe burner can effectively crush biological oil to form small molecules, but has high operation requirement, so that fuel cannot be ignited or flame is unstable easily, and high-viscosity substances are easy to coke, corrode and block through the nozzle, so that the working condition is unstable and the maintenance cost is high.

Due to the high viscosity, low thermal stability and high moisture characteristics of the pyrolysis volatiles, it is difficult to achieve efficient combustion and low nitrogen emissions with conventional burners. Therefore, there is a need to design a new burner to achieve efficient low nitrogen combustion of pyrolysis volatiles.

Disclosure of Invention

The first object of the present invention is to address the technical problems existing in the prior art: the utility model provides a hierarchical whirl low nitrogen combustor, including the open combustion casing in both ends, set gradually distribution chamber, toper return current room, toper expand flow room and delivery chamber in the longitudinal direction in the combustion casing. The air enters the distribution chamber, the conical reflux chamber and the conical flow expansion chamber in a tangential rotational flow mode through three different conveying paths respectively, and is fully mixed, atomized and crushed with the direct injection primary fuel and the tangential secondary fuel to form gas-liquid two-phase fuel, so that combustion stability is enhanced, and nitrogen oxide emission is reduced.

The second object of the invention is: the working method of the graded rotational flow low-nitrogen combustor comprises direct injection feeding, tangential air inlet, atomization crushing, conical backflow, double-channel rotational flow, conical flow expansion and tangential feeding air inlet, so that the combustion efficiency is effectively improved, and the emission of nitrogen oxides is reduced.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the utility model provides a hierarchical whirl low nitrogen combustor, including the open combustion casing in both ends, set gradually the distribution room in the longitudinal direction in the combustion casing, the toper return-flow chamber, toper expands flow chamber and delivery chamber, the distribution room provides the flow path for primary fuel and primary air, the distribution room includes a feeding passageway and a plurality of inlet channel of once setting around the feeding passageway circumference, the inlet channel is tangentially connected with the one end of toper return-flow chamber, the toper return-flow chamber is used for the mixed backward flow of primary fuel and primary air, the other end of toper return-flow chamber is connected with the one end of toper expansion flow chamber, the outside of toper return-flow chamber is equipped with the some igniters, still be equipped with a plurality of secondary inlet channel in the combustion casing, the one end of secondary inlet channel is tangentially connected with the one end of toper expansion flow chamber, the other end of secondary inlet channel extends to the outside of combustion casing, the other end of toper expansion flow chamber is connected with the entry end of delivery chamber, be equipped with a plurality of inlet feed channels on the circumference wall outside the delivery chamber, the inlet feed channel is used for carrying secondary fuel and tertiary air simultaneously, inlet channel is tangentially connected with the delivery chamber, the exit end blowout of delivery chamber.

Further, the primary feed channel is located at a central axis of the distribution chamber, and the plurality of primary feed channels are uniformly arranged around the primary feed channel.

Further, the tangential angle of the primary air intake passage and the conical return chamber is 30-89 degrees.

Further, the tangential directions of the connection of the plurality of primary air inlet channels and the conical return chamber are the same.

Further, the conical reflux chamber is opposite to the conical direction of the conical expansion chamber.

Further, the conical flow expansion chamber is further provided with a two-channel flow expansion chamber at the other end close to the conical flow expansion chamber, the two-channel flow expansion chamber is of a conical table structure, the two-channel flow expansion chamber comprises an outer cylinder body, an inner cylinder body sleeved in the outer cylinder body and a cover plate fixed between the outer cylinder body and the inner cylinder body, an outer flow expansion channel for conveying secondary air is formed between the outer cylinder body and the inner cylinder body, a plurality of through holes are formed in the cover plate, the secondary air inlet channel is tangentially connected with the through holes, the outer flow expansion channel is respectively in fluid communication with the secondary air inlet channel and the conical flow expansion chamber, an inner flow expansion channel for conveying primary fuel and primary air is formed in the inner cylinder body, and the inner flow expansion channel is respectively in fluid communication with the conical flow expansion chamber and the conical flow expansion chamber.

Further, the tangential directions of the connection of the plurality of secondary air inlet channels and the through holes are the same.

Further, the intake feed passage is provided perpendicular to the longitudinal direction of the combustion casing.

Further, the tangential angle of the inlet feed channel and the delivery chamber is 0-45 degrees.

The working method of the graded rotational flow low-nitrogen burner comprises the following steps:

s1, direct injection feeding and tangential injection: the primary fuel is directly injected and fed through a primary feeding channel of the distribution chamber, and primary air is tangentially injected through a primary air inlet channel of the distribution chamber;

s2, atomizing and crushing: the primary air atomizes and breaks the primary fuel and conveys the primary fuel into a conical reflux chamber;

s3, conical reflux: the primary fuel and the primary air entering the conical backflow chamber are mixed, backflow and ignited, and then are conveyed into the double-channel backflow chamber;

s4, double-channel rotational flow: secondary air enters the outer cyclone channel through the secondary air inlet channel, meanwhile, primary fuel and primary air enter the inner cyclone channel, and the primary fuel, the primary air and the secondary air are jointly conveyed into the conical flow expansion chamber;

s5, conical flow expansion: the primary fuel, the primary air and the secondary air are mixed in the conical flow expansion chamber, and the fuel is atomized and crushed again to strengthen the mixed combustion;

s6, tangential feeding air inlet: the secondary fuel and the tertiary air are tangentially fed into the conveying chamber through the air inlet feeding channel, the secondary fuel and the tertiary air are mixed with the primary fuel, the primary air and the secondary air for combustion, and finally flame is sprayed out from the outlet end of the conveying chamber.

The invention has the following advantages:

1. aiming at the characteristics of high viscosity, high moisture and low thermal stability of biological oil in biomass pyrolysis volatile matters, primary air is tangentially sprayed into and atomized to crush primary fuel, and then the primary fuel enters a conical reflux chamber; the flow speed of the liquid-phase fuel particles which are not atomized is reduced after the liquid-phase fuel particles enter the conical flow expansion chamber, the liquid-phase fuel particles advance along the wall surface of the flow expansion chamber under the action of swirl, and meanwhile, secondary air entering the outer swirl passage through the secondary air inlet passage is atomized and crushed again; the secondary fuel and the tertiary air are tangentially swirl-injected through an air inlet feed channel at the other end close to the combustion shell, and are atomized, crushed and mixed for three times under the interaction with the fuel and the air in the combustion shell. The atomization, crushing and full mixing of the gas-liquid two-phase fuel of biomass pyrolysis volatile matters are realized through three-stage rotational flow, the low-calorific-value fuel gas can be stably combusted, flame is not easy to extinguish, the fuel is fully combusted, and the combustion efficiency is greatly improved. Solves the problems of poor atomization, insufficient mixing and nozzle blockage in the traditional burner. The burner can be suitable for occasions such as power generation, garbage incineration, chemical treatment and the like.

2. According to the invention, air enters the distribution chamber, the conical reflux chamber and the conical flow expansion chamber in a tangential swirling manner through three different conveying paths respectively, and is fully mixed, atomized and crushed with the direct injection primary fuel and the tangential secondary fuel, so that more uniform mixing is realized, the local high temperature phenomenon caused by uneven mixing is avoided, and meanwhile, the high temperature area of flame is reduced and the emission of nitrogen oxides is reduced through the classification of the fuel and the air.

3. The grading rotational flow low-nitrogen burner has the advantages of compact structure, strong adaptability and good combustion stability, and can efficiently and cleanly burn biomass pyrolysis volatile matters with high viscosity, high water content and complex components.

4. The distribution chamber of the invention mixes the tangential jet of primary air with the direct jet of primary fuel to form a rotational flow, and simultaneously improves the speed and rotational flow strength of air flow through the conical backflow chamber immediately after the rotational flow is formed, and promotes the conical backflow chamber to generate stronger backflow through the improvement of the axial speed and strength of the rotational flow, so that the temperature of the fuel and the air realizes the stable combustion of main flame through backflow, the unstable combustion and flameout phenomenon of biomass pyrolysis volatile matters caused by high viscosity, high moisture and poor thermal stability are prevented, and meanwhile, the problems of greatly reducing the axial rotational flow speed and strength caused by the formation of the rotational flow are avoided through the structure of the rotational flow and the conical backflow chamber.

Drawings

FIG. 1 is a perspective cutaway view of a staged swirl low nitrogen burner of the present invention.

FIG. 2 is a schematic structural view of the staged swirl low nitrogen burner of the present invention.

Fig. 3 is a front view of a dispensing chamber of the present invention.

Fig. 4 is a perspective cutaway view of fig. 3 along A-A.

Fig. 5 is a schematic view of the construction of the conical reflow chamber and the dual channel reflow chamber of the present invention.

Fig. 6 is a schematic view of the structure of the dual channel swirl chamber of the present invention.

FIG. 7 is a schematic view of the configuration of the tapered diffusion chamber and transfer chamber of the present invention.

Fig. 8 is a cross-sectional view of a transfer chamber of the present invention.

FIG. 9 is a flow chart of the operation of the staged swirl low nitrogen burner of the present invention.

Wherein, C is combustion casing, 1 is the distribution chamber, 101 is the primary feed channel, 102 is the primary air inlet channel, 102a is the air inlet, 102b is the air outlet, 103 is the distribution chamber body, 2 is the toper reflow chamber, 201 is the toper backflow cylinder, 202 is the igniter, 203 is the baffle, 203a is the connecting hole, 3 is the toper expands the flow chamber, 301 is the secondary air inlet channel, 302 is the toper expands flow cylinder, 4 is the delivery chamber, 401 is the air inlet feed channel, 402 is the delivery cylinder, 402a is the entry, 5 is the binary channels swirl chamber, 501 is the outer cylinder, 502 is the inner cylinder, 503 is the apron, 503a is the through-hole, 504 is the outer swirl channel, 505 is the inner swirl channel.

Detailed Description

The invention will be described in further detail with reference to the drawings and the detailed description.

As shown in fig. 1-2, X is the longitudinal direction of the combustion casing and Y is the transverse direction of the combustion casing. The utility model provides a hierarchical whirl low nitrogen combustor, including the open combustion casing in both ends, set gradually distribution chamber in the longitudinal direction in the combustion casing, the toper return-flow chamber, toper diffusion chamber and delivery chamber, the one end of combustion casing cooperatees with the entry end of distribution chamber, the distribution chamber provides the flow path for primary fuel and primary air, the distribution chamber includes a feed channel and a plurality of primary air inlet channel that set up around the feed channel circumference, the one end tangential connection of primary air inlet channel and toper return-flow chamber, the one end tangential entry toper return-flow chamber forms the whirl, the toper return-flow chamber is used for the mixed backward flow of primary fuel and primary air, the other end of toper return-flow chamber is connected with the one end of toper diffusion chamber, the outside of toper return-flow chamber is equipped with the some igniters, still be equipped with a plurality of secondary air inlet channels in the combustion casing, the one end tangential connection of secondary air inlet channel and one end of toper diffusion chamber, the other end tangential entry secondary air tangential entry toper diffusion chamber forms the whirl, the other end tangential entry of secondary air inlet channel extends to the outside of combustion casing, the other end and delivery chamber's entry end tangential connection, be equipped with a plurality of feed channels and fuel inlet channel and tertiary air outlet, the tangential connection of the combustion chamber, the tertiary air and the combustion chamber and the other end and the delivery chamber are all used for the flame, the combustion chamber is blown out to the delivery to the other end. In this embodiment, one end of the combustion housing has an input port, the other end of the combustion housing has an output port, the inlet end of the distribution chamber is flush with the input port of the combustion housing, the outlet end of the delivery chamber is flush with the output port of the combustion housing, and the other end of the secondary air intake passage extends toward and is flush with the input port of the combustion housing. The combustion shell is of a cylindrical structure, and the distribution chamber, the conical reflux chamber, the conical expansion chamber and the conveying chamber are all detachably arranged in the combustion shell, so that parts can be replaced conveniently and parameters can be adjusted conveniently. The primary fuel and the secondary fuel refer to pyrolysis volatile matters in the biomass pyrolysis charcoal making process, the main components of the pyrolysis volatile matters comprise pyrolysis gas and biological oil, and the primary air, the secondary air and the tertiary air can be gases with a certain temperature or gases added with other chemical components.

As shown in fig. 1-4, the primary feed channels are located at the central axis of the distribution chamber, and the plurality of primary feed channels are uniformly arranged around the primary feed channels. The number of the primary air inlet channels is 3-10, of course, the number of the primary air inlet channels can be configured according to actual needs, and the diameter of the primary air inlet channels is determined according to parameters such as structural space, flow rate of primary air, speed and the like. In this embodiment, the distribution chamber further includes a distribution chamber body, the distribution chamber body is in a cylindrical structure, the primary feed channels are located on a central axis of the distribution chamber body, the primary feed channels are used for directly injecting primary fuel into the conical return chamber, the number of the primary feed channels is six, the six primary feed channels are uniformly distributed around the circumferential direction of the primary feed channels, the six primary feed channels are respectively tangentially connected with one end of the conical return chamber, and the primary feed channels are used for tangentially entering primary air into the conical return chamber. The primary air inlet channel penetrates through the distribution chamber body and is obliquely arranged towards one direction, that is, the air inlet and the air outlet of the primary air inlet channel are not on the same axis, and primary air tangentially enters the conical reflux chamber through the primary air inlet channel obliquely arranged on the distribution chamber body, so that primary air is swirled.

As shown in fig. 3 and 4, the tangential angle α of the primary air intake passage and the conical return chamber is 30-89 °, preferably 45 °, so as to achieve the best combustion effect by detachably replacing the distribution chambers of different types, i.e. by configuring the primary air intake passages with different tangential angles and numbers. The tangential directions of the connection of the plurality of primary air inlet channels and the conical backflow chamber are the same, that is, the plurality of primary air inlet channels are obliquely arranged in the distribution chamber in the same direction, and primary air can enter the conical backflow chamber in the tangential direction in the same direction, so that the air swirling effect is better. Regarding the type selection of the distribution chamber, firstly, according to parameters such as the proportion of liquid phase products in biomass pyrolysis volatile matters, component proportion, viscosity, moisture content, thermal stability and the like, a primary air inlet channel with a certain tangential angle is selected, a corresponding distribution chamber is selected, and the distribution chamber is installed in a combustion shell; and secondly, according to the mixed combustion condition of the fuel and the air, the proportion and the speed of the primary fuel, the secondary fuel, the primary air, the secondary air and the tertiary air are finely adjusted, so that more accurate combustion control is realized. The distribution chamber adopts a channel with a fixed angle instead of an adjustable angle, so as to prevent the biological oil in the pyrolysis volatile from being too viscous to adhere to the adjustable component, thereby blocking the channel of the distribution chamber.

As shown in fig. 5, the conical reflux chamber comprises a conical reflux cylinder, one end of the conical reflux cylinder is provided with a baffle plate, a plurality of connecting holes are formed in the baffle plate, the connecting holes correspond to the air outlets of the primary air inlet channels, the other end of the conical reflux cylinder is in fluid communication with one end of the conical reflux chamber, and an igniter is further arranged outside the conical reflux cylinder.

As shown in fig. 1, the conical return chamber is in the opposite conical direction to the conical diffuser chamber. The conical reflux chamber is of a conical structure and is divided into a dispersing area and a concentrating area, primary air and primary fuel firstly pass through the dispersing area and then flow through the concentrating area, and the flow speed of the primary air in the concentrating area can be accelerated, so that slow gas in the dispersing area is driven to form reflux, and the mixing effect is enhanced. The conical flow expansion chamber is in a conical structure and is divided into a diffusion area and a concentration area, and primary air and primary fuel firstly pass through the concentration area and then flow through the diffusion area. That is, the process of sequentially passing the primary air and the primary fuel through the tapered reflux chamber and the tapered diffusion chamber is dispersion-concentration-diffusion, so that the tapered reflux chamber and the tapered diffusion chamber have opposite tapered directions.

As shown in fig. 1, 5 and 6, the conical flow expansion chamber is further provided with a two-channel flow expansion chamber at the other end close to the conical flow expansion chamber, the two-channel flow expansion chamber is detachably arranged between the conical flow expansion chamber and the conical flow expansion chamber, the two-channel flow expansion chamber is respectively in fluid communication with the conical flow expansion chamber and the conical flow expansion chamber, the two-channel flow expansion chamber is of a conical table structure, the two-channel flow expansion chamber comprises an outer cylinder body, an inner cylinder body sleeved in the outer cylinder body and a cover plate fixed between the outer cylinder body and the inner cylinder body, an outer flow expansion channel for conveying secondary air is formed between the outer cylinder body and the inner cylinder body, a plurality of through holes are formed in the cover plate, the secondary air inlet channel is tangentially connected with the through holes, the outer flow expansion channel is respectively in fluid communication with the secondary air inlet channel and the conical flow expansion chamber, secondary air tangentially enters the outer flow expansion channel to form rotational flow, then enters the conical flow expansion chamber to continue rotational flow, an inner flow channel for conveying primary fuel and primary air is formed in the inner cylinder body, and the inner flow expansion channel is respectively in fluid communication with the conical flow expansion chamber. The tangential directions of the connection of the plurality of secondary air inlet channels and the through holes are the same. The length of the double-channel swirl chamber is 30-160mm, and the length of the double-channel swirl chamber is determined according to the swirl strength and speed of secondary air. In this embodiment, the number of secondary air inlet channels is four, and the apron corresponds to be equipped with four through-holes, and on the apron that four secondary air inlet channels evenly set up, secondary air inlet channels have straightway and slope section, straightway and distribution chamber parallel arrangement, slope section and toper backward flow room parallel arrangement, and the one end of straightway flushes with the input port of burning casing, and the other end of straightway is connected with the one end of slope section, and the other end of slope section is tangential with the through-hole to be connected, that is to say, the flow path of secondary air inlet channel corresponds with distribution chamber, toper backward flow room setting's shape. Through the setting of binary channels swirl chamber, can realize the even steady burning of flame, make flame not squint and be in the central region of combustor, can not cause the overheated damage of combustor.

As shown in fig. 1, 7 and 8, the intake feed passage is provided perpendicularly to the longitudinal direction of the combustion casing. The tangential angle beta of the inlet feed channel to the transfer chamber is 0-45 deg., preferably 0 deg.. In this embodiment, the delivery chamber is the cylindric structure, and the delivery chamber includes the delivery barrel, and the interval is equipped with a plurality of inlets on the circumference wall of delivery barrel, and inlet feed channel's one end and entry tangential connection, inlet feed channel's the other end pass the combustion casing and extend outside the combustion casing. The number of inlets is 2-8, the number of inlet feed channels is 2-8, the number of inlets corresponds to the number of inlet feed channels, in this embodiment, the number of inlets is four, the number of inlet feed channels is four, and four inlet feed channels are uniformly arranged on the conveying cylinder. The inlet and the output port of the combustion shell are separated by a certain distance, so that secondary fuel and tertiary air are prevented from being directly discharged from the output port of the combustion shell when entering the conveying chamber, wherein the distance between the inlet and the output port of the combustion shell is 30-70mm, and the distance between the air inlet feeding channel and the output port of the combustion shell is 30-70mm. The multiple air inlet feed channels are arranged on the same horizontal plane in the transverse direction of the combustion shell, and the tangential directions of the multiple air inlet feed channels and the inlet connection are the same, so that secondary fuel and tertiary air can enter the conveying chamber tangentially in the same direction and on the same horizontal plane, and swirl and internal fuel and air are formed to be fully mixed for combustion. The tangential angle of the air inlet feed channel and the position of the inlet can be adjusted according to parameters such as flame length, flame width, combustion heat load, gas-liquid two-phase mixing degree, rotational flow strength and the like.

As shown in fig. 9, a method for operating a staged swirl low nitrogen burner includes the steps of:

s1, direct injection feeding and tangential injection: the primary fuel is directly injected and fed through a primary feeding channel of the distribution chamber, and primary air is tangentially injected through a primary air inlet channel of the distribution chamber;

s2, atomizing and crushing: the primary air atomizes and breaks the primary fuel and conveys the primary fuel into a conical reflux chamber; the tangential jet of the primary air through the primary air inlet channel increases the rotational flow strength of the primary air under the action of the conical reflux chamber, enhances the tangential angle of the primary fuel, and generates strong collision with the primary fuel directly injected by the primary air inlet channel so as to atomize and crush pyrolysis volatile matters;

s3, conical reflux: the primary fuel and the primary air entering the conical backflow chamber are mixed, backflow and ignited, and then are conveyed into the double-channel backflow chamber; the primary air passes through the primary air inlet channel to generate rotational flow so as to enable the air to diffuse outwards and flow through the conical reflux chamber, and the conical reflux chamber is in a conical structure and is divided into a dispersing area and a concentrating area, wherein the primary air passes through the dispersing area and then flows through the concentrating area, so that the flow speed of the primary air in the concentrating area is increased, slow gas in the dispersing area is driven to form reflux, and the mixing effect is enhanced;

s4, double-channel rotational flow: secondary air enters the outer cyclone channel through the secondary air inlet channel, meanwhile, primary fuel and primary air enter the inner cyclone channel, and the primary fuel, the primary air and the secondary air are jointly conveyed into the conical flow expansion chamber;

s5, conical flow expansion: the primary fuel, the primary air and the secondary air are mixed in the conical flow expansion chamber, and the fuel is atomized and crushed again to strengthen the mixed combustion; the flow speed of the fuel and the air is reduced under the action of the conical flow expansion, and unburned fuel particles advance along the wall surface of the conical flow expansion chamber under the action of the rotational flow; at the moment, secondary air enters the conical flow expansion chamber through the outer swirl channel to form swirl, on one hand, the secondary air clings to the inner surface of the conical flow expansion chamber to protect the secondary air from being worn and corroded by biological oil at high temperature, and on the other hand, the secondary air atomizes and breaks unburnt fuel particles again, and enhances mixing and enhanced combustion;

s6, tangential feeding air inlet: the secondary fuel and the tertiary air are tangentially fed into the conveying chamber through the air inlet feeding channel, the secondary fuel and the tertiary air are mixed with the primary fuel, the primary air and the secondary air for combustion, and finally flame is sprayed out from the outlet end of the conveying chamber. The secondary fuel and the tertiary air enter the main flame through the air inlet feed channel at the other end close to the combustion shell, interact with the main air flow to strengthen atomization, crushing and mixing, and meanwhile, the radial speed of the main flame can be enhanced, the swirl strength is improved, the backflow is strengthened, the flame is stabilized, the section heat load of the main flame is enhanced, and the flame length is shortened.

The burner of the invention supplies the air and fuel needed by combustion in a grading way, wherein the air is respectively introduced into the primary air channel from the primary air inlet channel, the secondary air is introduced into the outer swirl channel, the tertiary air is introduced into the air inlet feeding channel, the fuel is respectively directly injected into the primary fuel from the primary feeding channel from the primary air inlet channel in a proportion, and the secondary fuel is tangentially introduced into the air inlet feeding channel. While staged air feed is a simultaneous and continuous process, i.e., primary fuel, secondary fuel are fed simultaneously, and primary air, secondary air, and tertiary air are fed simultaneously.

In general, the present invention addresses the high viscosity, high moisture and low thermal stability characteristics of bio-oil in biomass pyrolysis volatiles by swirling and tangentially spraying and atomizing primary air to break up primary fuel, which then enters a conical reflow chamber; the flow speed of the liquid-phase fuel particles which are not atomized is reduced after the liquid-phase fuel particles enter the conical flow expansion chamber, the liquid-phase fuel particles advance along the wall surface of the flow expansion chamber under the action of swirl, and meanwhile, secondary air entering the outer swirl passage through the secondary air inlet passage is atomized and crushed again; the secondary fuel and the tertiary air are tangentially swirl-injected through an air inlet feed channel at the other end close to the combustion shell, and are atomized, crushed and mixed for three times under the interaction with the fuel and the air in the combustion shell. The atomization, crushing and full mixing of the gas-liquid two-phase fuel of biomass pyrolysis volatile matters are realized through three-stage rotational flow, the low-calorific-value fuel gas can be stably combusted, flame is not easy to extinguish, the fuel is fully combusted, and the combustion efficiency is greatly improved. Solves the problems of poor atomization, insufficient mixing and nozzle blockage in the traditional burner. The burner can be suitable for occasions such as power generation, garbage incineration, chemical treatment and the like. According to the invention, air enters the distribution chamber, the conical reflux chamber and the conical flow expansion chamber in a tangential swirling manner through three different conveying paths respectively, and is fully mixed, atomized and crushed with the direct injection primary fuel and the tangential secondary fuel, so that more uniform mixing is realized, the local high temperature phenomenon caused by uneven mixing is avoided, and meanwhile, the high temperature area of flame is reduced and the emission of nitrogen oxides is reduced through the classification of the fuel and the air. The grading rotational flow low-nitrogen burner has the advantages of compact structure, strong adaptability and good combustion stability, and can efficiently and cleanly burn biomass pyrolysis volatile matters with high viscosity, high water content and complex components. The distribution chamber of the invention mixes the tangential jet of primary air with the direct jet of primary fuel to form a rotational flow, and simultaneously improves the speed and rotational flow strength of air flow through the conical backflow chamber immediately after the rotational flow is formed, and promotes the conical backflow chamber to generate stronger backflow through the improvement of the axial speed and strength of the rotational flow, so that the temperature of the fuel and the air realizes the stable combustion of main flame through backflow, the unstable combustion and flameout phenomenon of biomass pyrolysis volatile matters caused by high viscosity, high moisture and poor thermal stability are prevented, and meanwhile, the problems of greatly reducing the axial rotational flow speed and strength caused by the formation of the rotational flow are avoided through the structure of the rotational flow and the conical backflow chamber.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims (10)

1. A staged swirl low nitrogen burner, characterized by: the combustion device comprises a combustion shell with two open ends, wherein a distribution chamber, a conical backflow chamber, a conical expansion chamber and a conveying chamber are sequentially arranged in the longitudinal direction of the combustion shell, the distribution chamber provides a flow path for primary fuel and primary air, the distribution chamber comprises a primary feeding channel and a plurality of primary air inlet channels which are circumferentially arranged around the primary feeding channel, the primary air inlet channels are tangentially connected with one end of the conical backflow chamber, the conical backflow chamber is used for mixed backflow of the primary fuel and the primary air, the other end of the conical backflow chamber is connected with one end of the conical expansion chamber, an igniter is arranged outside the conical backflow chamber, a plurality of secondary air inlet channels are further arranged in the combustion shell, one end of the secondary air inlet channels is tangentially connected with one end of the conical expansion chamber, the other end of the secondary air inlet channels extend towards the outside of the combustion shell, the other end of the conical expansion chamber is connected with the inlet end of the conveying chamber, a plurality of air inlet feeding channels are arranged on the circumferential wall outside the conveying chamber, the air inlet feeding channels are used for simultaneously conveying secondary fuel and tertiary air, the air inlet channels are tangentially connected with the conveying chamber, and flame is sprayed out from the outlet end of the conveying chamber.

2. A staged swirl low nitrogen burner as defined in claim 1, wherein: the primary feed channels are located at the central axis of the distribution chamber, and the plurality of primary feed channels are uniformly arranged around the primary feed channels.

3. A staged swirl low nitrogen burner according to claim 1 or 2, characterized in that: the tangential angle of the primary air inlet channel and the conical return chamber is 30-89 degrees.

4. A staged swirl low nitrogen burner according to claim 1 or 2, characterized in that: the tangential directions of the connection of the plurality of primary air inlet channels and the conical backflow chamber are the same.

5. A staged swirl low nitrogen burner as defined in claim 1, wherein: the conical reflux chamber and the conical expansion chamber are opposite in conical direction.

6. A staged swirl low nitrogen burner as defined in claim 1, wherein: the conical flow expansion chamber is also provided with a double-channel flow expansion chamber at the other end close to the conical flow expansion chamber, the double-channel flow expansion chamber is of a conical table structure, the double-channel flow expansion chamber comprises an outer cylinder body, an inner cylinder body sleeved in the outer cylinder body and a cover plate fixed between the outer cylinder body and the inner cylinder body, an outer flow expansion channel for conveying secondary air is formed between the outer cylinder body and the inner cylinder body, a plurality of through holes are formed in the cover plate, the secondary air inlet channel is tangentially connected with the through holes, the outer flow expansion channel is respectively in fluid communication with the secondary air inlet channel and the conical flow expansion chamber, an inner flow expansion channel for conveying primary fuel and primary air is formed in the inner cylinder body, and the inner flow expansion channel is respectively in fluid communication with the conical flow expansion chamber and the conical flow expansion chamber.

7. A staged swirl low nitrogen burner as defined in claim 6, wherein: the tangential directions of the connection of the plurality of secondary air inlet channels and the through holes are the same.

8. A staged swirl low nitrogen burner as defined in claim 1, wherein: the intake feed passage is disposed perpendicularly to the longitudinal direction of the combustion casing.

9. A staged swirl low nitrogen burner as defined in claim 1, wherein: the tangential angle of the inlet feed channel and the conveying chamber is 0-45 degrees.

10. A method of operating a staged swirl low nitrogen burner according to any of claims 1 to 9, characterized in that: the method comprises the following steps:

s1, direct injection feeding and tangential injection: the primary fuel is directly injected and fed through a primary feeding channel of the distribution chamber, and primary air is tangentially injected through a primary air inlet channel of the distribution chamber;

s2, atomizing and crushing: the primary air atomizes and breaks the primary fuel and conveys the primary fuel into a conical reflux chamber;

s3, conical reflux: the primary fuel and the primary air entering the conical backflow chamber are mixed, backflow and ignited, and then are conveyed into the double-channel backflow chamber;

s4, double-channel rotational flow: secondary air enters the outer cyclone channel through the secondary air inlet channel, meanwhile, primary fuel and primary air enter the inner cyclone channel, and the primary fuel, the primary air and the secondary air are jointly conveyed into the conical flow expansion chamber;

s5, conical flow expansion: the primary fuel, the primary air and the secondary air are mixed in the conical flow expansion chamber, and the fuel is atomized and crushed again to strengthen the mixed combustion;

s6, tangential feeding air inlet: the secondary fuel and the tertiary air are tangentially fed into the conveying chamber through the air inlet feeding channel, the secondary fuel and the tertiary air are mixed with the primary fuel, the primary air and the secondary air for combustion, and finally flame is sprayed out from the outlet end of the conveying chamber.