CN214064913U - Low-nitrogen burner - Google Patents

Abstract

The utility model discloses a low-nitrogen burner, include: mounting a plate; the diffusion tube is vertically arranged on the mounting plate, an inner tube longitudinally and convexly extending out of the diffusion tube is embedded in the diffusion tube, and a plurality of ignition spray tubes are annularly distributed on the inner side of the inner tube; the recycling sleeve is sleeved outside the inner cylinder and longitudinally separated from the diffusion cylinder, a plurality of fuel spray pipes are annularly distributed on the outer side of the recycling sleeve, and the free end of the recycling sleeve forms an annular contraction part which radially and inwardly contracts; the flame stabilizing disc is vertically penetrated with a central spray pipe; the fuel spray pipe consists of a main fuel spray pipe and a gas transmission pipe connected with the main fuel spray pipe; the tail end of the recirculation sleeve forms an annular first gas mixing inlet, and the joint of the main fuel spray pipe and the gas conveying pipe forms a second gas mixing inlet positioned in front of the first gas mixing inlet. The utility model provides an among the prior art ultralow nitrogen combustor light peripheral flame's the not good problem of effect just to the suppression effect that nitrogen oxide discharged.

Description

Low-nitrogen burner

Technical Field

The utility model relates to a low-nitrogen burner technical field especially relates to a low-nitrogen burner.

Background

Industrial boilers, tunnel kilns, and large industrial heaters are generally provided with a burner using natural gas (mainly methane) or oil or other fossil fuel as a fuel, and generate heat by combustion. The prior art burners basically adopt the diffusion combustion technology, and a main spray gun and a cyclone disk are usually arranged in the burners. The natural gas is preheated in the first half section of the main spray gun, and then the natural gas and the air are mixed and combusted. However, the tail gas of the burner with the structure still has higher NO_XThe problem (2) does not meet the national requirements of energy conservation, emission reduction and environmental protection. The low-nitrogen burner is one kind of burner with the aim of reducing the generation of NO harmful to environment during combustion_X(i.e., oxynitride).

After the applicant searches carefully, the chinese patent publication CN109099425A also discloses an ultra-low nitrogen burner with flue gas internal circulation. This prior art adopts and surely fires fuel pipe and swirler and plays the effect of stable flame. Thermal nox is nitrogen oxide generated by oxidizing N2 in combustion air at high temperature, is also the largest source of nitrogen oxide in boiler combustion, and is a key issue for controlling low nox emission. In this conventional technology, although the conical ring is added to the outer side of the swirler, a part of the fuel ejected from the staged fuel pipe collides with the conical ring, thereby increasing the mixing of the fuel and air, promoting stable combustion, promoting the formation of the internal circulation of the flue gas, and reducing the temperature in the combustion region. However, the applicant has pointed out that the swirler of this prior art is recessed in the centre of the conical ring, which in fact only has the technical effect of gathering the flame. Although the flue gas entrainment ring disclosed by the invention can realize flue gas internal circulation to a certain extent, a circle of entrainment holes formed in the flue gas entrainment ring are far away from the swirler, so that the technical effect of remarkably reducing nitrogen oxides by arranging the flue gas entrainment ring is doubtful, and the effect of igniting peripheral flames by the burner disclosed by the prior art is poor.

In view of the above, there is a need for an improved ultra low nitrogen burner of the prior art to solve the above problems.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to disclose a low nitrogen combustor to the ultralow nitrogen combustor who solves among the prior art lights the not good problem of the suppression effect that peripheral flame is not good and discharges nitrogen oxide.

To achieve one of the above objects, the present invention firstly discloses a low-nitrogen burner, comprising:

mounting a plate;

the diffusion tube is vertically arranged on the mounting plate, an inner tube which longitudinally protrudes out of the diffusion tube is embedded in the diffusion tube, and a plurality of ignition spray tubes are annularly distributed on the inner side of the inner tube;

the recycling sleeve is sleeved outside the inner barrel and longitudinally separated from the diffusion barrel, a plurality of fuel spray pipes are annularly distributed on the outer side of the recycling sleeve, and the free end of the recycling sleeve forms an annular contraction part which contracts inwards in the radial direction; and the number of the first and second groups,

the flame stabilizing disc is vertically penetrated with a central spray pipe;

the fuel spray pipe consists of a main fuel spray pipe and a gas transmission pipe connected with the main fuel spray pipe, and the free end of the main fuel spray pipe is formed in front of the side of the free end of the inner cylinder;

the tail end of the recirculation sleeve forms an annular first gas mixing inlet, and a second gas mixing inlet located in front of the first gas mixing inlet side is formed at the joint of the main fuel spray pipe and the gas conveying pipe.

As a further improvement of the present invention, the main fuel nozzle is attached to the outer sidewall of the recirculation sleeve.

As a further improvement of the present invention, one end of the diffusion cylinder close to the recirculation sleeve forms a radially-inwardly contracted ring portion, and the gas pipe is located outside the diffusion cylinder and vertically arranged on the mounting plate;

the gas conveying pipe is composed of a first vertical section which is vertically arranged on the mounting plate and is close to the outer side of the diffusion cylinder, an inclined section which is connected with the first vertical section and the inclined direction of which is matched with the contraction direction of the reducing ring part, and a second vertical section which is connected with the inclined section and is parallel to the longitudinal axis direction of the recirculation sleeve.

As a further improvement of the utility model, the free end of gas-supply pipe vertically run through in the main fuel spray pipe, just the pipe wall of main fuel spray pipe is formed with a plurality of ventholes around gas-supply pipe free end direction annular arrangement, and is a plurality of the venthole forms the second that is located first gas inlet side the place ahead of mixing and mixes the gas entry.

As a further improvement of the utility model, the input end of the main fuel spray pipe is formed with a window for the free end of the gas transmission pipe to penetrate through, and the outer pipe wall of the gas transmission pipe is attached to the edge of the window at the input end of the main fuel spray pipe;

the size of the radial surface of the window is smaller than the size of the radial section of the main fuel spray pipe, and the plurality of air outlets are uniformly distributed on the pipe wall of the main fuel spray pipe in a surrounding mode.

As a further improvement, the free end of the main fuel nozzle forms an inclined plane facing the outside, and the inclined plane is an acute angle with the included angle formed by the central axis of the central nozzle.

As a further improvement, the second mixes the gas entry and is formed by main fuel spray tube and gas-supply pipe longitudinal separation, just the terminal surface of the free end of main fuel spray tube with the parallel and phase-match of transverse section of main fuel spray tube.

As a further improvement of the present invention, the free end of the main fuel nozzle is disposed in the open side front of the inner tube.

As a further improvement of the utility model, a heat-insulating cylinder which partially wraps the gas pipe and the diffusion cylinder is arranged outside the diffusion cylinder, and heat-insulating materials are filled inside the heat-insulating cylinder;

and a plurality of connecting plates which are arranged in the radial direction are arranged between the recycling sleeve and the inner barrel, and the connecting plates extend to the outer wall surface of the radial shrinkage ring part along the longitudinal extension direction of the recycling sleeve.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model discloses an among the low nitrogen combustor, the second that forms through a plurality of ventholes that are set up by the pipe wall of main fuel spray tube mixes the gas entry, realizes the circulation of the flue gas that the combustion chamber of boiler formed in the fuel combustion process to improve the cyclic utilization ratio of flue gas. Meanwhile, an annular first gas mixing inlet is formed at the tail end of the recirculation sleeve and the diffusion cylinder is used, so that the air flow rate is improved, the circulation utilization rate of the flue gas is further improved, and the energy density of the fuel conveyed to the combustion chamber by the main fuel spray pipe is reduced by mixing the flue gas containing the reductive ion components into the first gas mixing channel. Meanwhile, the annular contraction part formed by the free end of the recirculation sleeve guides gas sprayed by the main fuel spray pipe to be radially gathered towards the central axis of the central spray pipe in the direction of the low-pressure area, so that the gas sprayed by the main fuel spray pipe can be easily ignited by flame at the flame stabilizing disc to form a circle of main flame, the mixed gas in the combustion chamber can be fully combusted, and the discharge amount of thermal nitrogen oxides can be effectively reduced. Therefore, the problems that the effect of igniting peripheral flame of the ultra-low nitrogen burner in the prior art is poor and the suppression effect of nitrogen oxide emission is poor are solved. Furthermore, the main fuel spray pipe is arranged close to the outer side of the recirculation sleeve, so that flame ignited by the pilot nozzle can conveniently ignite the main fuel spray pipe on the periphery.

Drawings

Fig. 1 is a schematic view of the internal structure of a low-nitrogen burner according to an embodiment of the present invention;

fig. 2 is a schematic view of the internal structure of a low-nitrogen burner according to another embodiment of the present invention;

FIG. 3 is a schematic external view of an air inducing apparatus connected to a low-nitrogen burner shown in FIG. 1;

FIG. 4 is a perspective view of a low-nitrogen burner according to the present invention;

FIG. 5 is a side view of a low-nitrogen burner of the present invention;

FIG. 6 is a schematic view of a low-nitrogen burner shown in FIG. 1 assembled with a furnace wall;

FIG. 7 is a conceptual diagram of the gas flow path and the flame spray path in a low-NOx burner of the present invention;

FIG. 8 is a schematic view of the internal structure of an air inducing device connected to a low-nitrogen burner shown in FIG. 1;

fig. 9 is a schematic structural view of a fuel nozzle in a low-nitrogen combustor according to the present invention.

Detailed Description

The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that the functions, methods, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.

It should be understood that in the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", etc. indicate the orientation or positional relationship indicated on the drawings, which is only for convenience of describing the present technical solution and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the technical solution.

The first embodiment is as follows:

before describing a low-nitrogen burner of the present invention in detail, it is necessary to explain the related technical concept. A low-nitrogen burner disclosed in this embodiment is horizontally butted with components corresponding to the view shown in fig. 2 and 3, and is embedded and installed in the furnace wall 100 of fig. 6. The furnace wall 100 may be part of a boiler. The terms "inboard" and "outboard" referring to spatial orientation are relative to the middle of FIG. 4The central axis 200 of the cardiojet 30. The anteroposterior positional relationship in terms of "lateral front" and "lateral rear" indicating the spatial orientation each refer to a longitudinal direction in the view shown in fig. 1 or 2, in which a direction away from the mounting plate 52 is "front" and a direction close to the mounting plate 52 is "rear". Thus, "lateral anterior" and "lateral posterior" refer to both the radial direction and the longitudinal direction relative to the central axis 200. Meanwhile, in the present embodiment, the term "low nitrogen" has a technical meaning equivalent to the term "low nitrogen oxide" (low NOx). "fuel" refers specifically to a flowable and combustible gas, and in this embodiment, applicant selects natural gas (its main components are methane, CH)₄) For exemplary purposes, therefore, "fuel" and "natural gas" are understood to be equivalent technical features in the present embodiments.

An embodiment of a low-nitrogen burner of the present invention is disclosed with reference to fig. 1 to 9.

The present embodiment discloses a low-nitrogen burner, which includes: the mounting plate 52 is a diffusion tube 60 vertically arranged on the mounting plate 52, the diffusion tube 60 is embedded with an inner tube 40 longitudinally protruding out of the diffusion tube, and a plurality of ignition nozzles 80 are annularly distributed on the inner side of the inner tube; the recycling sleeve 10 is sleeved outside the inner cylinder 40 and longitudinally separated from the diffusion cylinder 60, and a plurality of fuel spray pipes are annularly distributed on the outer side of the recycling sleeve 10; and a flame stabilizing disc 31, wherein a central spray pipe 30 vertically penetrates through the flame stabilizing disc 31. The fuel nozzle is composed of a main fuel nozzle 20 and a gas pipe 21 connected with the main fuel nozzle 20. Specifically, the mounting plate 52 is circular and is attached to the inner wall surface of the furnace wall 100 by bolts (not shown) for secure attachment, thereby mounting the entire low-nitrogen burner on the inner wall surface of the furnace wall 100. Meanwhile, the diffusion cylinder 60, the central nozzle 30, the recirculation sleeve 10, the flame stabilizing disc 31 and other solid components are all made of heat-resistant stainless steel alloy capable of bearing the temperature of more than 1200 ℃.

As explained in connection with fig. 7, the free end of the recirculation sleeve 10 forms an annular constriction 11 which constricts radially inwards, to compress the pilot flame formed by pilot lance 80, and to cause the end of annular constriction 11 to form a low-pressure zone M2, because the gas 213 from the main fuel lance 20 creates a high pressure region M1 forward of the low pressure region M2, thus, by virtue of the provision of the annular constriction 11, the gas 213 which is injected from the main fuel lance 20 is guided radially closer to the central axis 200 of the central lance 30 in the direction of the low-pressure region M2 (for example, the jet path of the gas 213a is radially closer to the jet path of the gas 213 b), thereby facilitating the flame at flame plate 31 to more easily ignite the gases exiting main fuel lance 20, to form a ring of main flames 213', and to ensure sufficient combustion of the mixed gas in the combustion chamber 400, and to effectively reduce the discharge amount of thermal type nitrogen oxides. Therefore, the problems that the effect of igniting the peripheral flame of the ultra-low nitrogen burner in the prior art is poor and the suppression effect of oxide emission is poor are solved. The inner wall surface of the annular constriction 11 may form an angle of 60 degrees or another angle with the central axis 200 of the central nozzle 30, so as to squeeze the pilot flame 96 through the annular constriction 11.

The low-nitrogen burner is connected to an air inducing device 70 shown in fig. 3. The function of the air inducing device 70 is to suck air containing oxygen (oxygen content is about 21%) from the outside. The air inducing device 70 includes a burner body 50, a motor 72, a controller 71, and a hood 73 communicating with the motor 72. A valve (not shown) for controlling the air flow is arranged in the air cover 73, and a valve (not shown) for controlling the gas flow is arranged in the gas delivery manifold 51. The controller 71 can be a single chip or a PLC controlled control hardware to control the rotation speed and operation time of the motor 72. The controller 71 and the motor 72 are both connected to the mains supply. Specifically, in this embodiment, the controller 71 is a siemens LMV intelligent controller.

An output shaft (not shown) of the motor 72 is provided with blades at a portion of the hood 73 to form an air flow 300 by rotation of the blades. The air flow 300 may penetrate the combustor body 50 and form an air flow as shown by arrows 94 and an air flow as shown by arrows 99 under the action of the diffuser 60 and the inner cylinder 40, respectively. An air inlet 74 is formed at the bottom of the hood 73, and air in the outside enters the hood 73 along an arrow 704. The air flow 300 simultaneously passes into the annular cavity 17 formed by the diffuser 60 and the inner barrel 40 and the annular cavity 18 formed by the central nozzle 30 and the inner barrel 40. The air plays a combustion supporting role in the combustion process of the natural gas.

As shown in fig. 3, 6 and 8, the mounting plate 52 connects the burner body 50 and the gas delivery manifold 51. Natural gas is introduced into the gas delivery manifold 51 in the direction of arrow 501. The cross-sectional area of the gas delivery manifold 51 is S5. The burner body 50 is hollow and connected to a gas delivery main pipe 51, and the burner body 50 has a duct 54 and a duct 53. The conduit 54 communicates with the central nozzle 30 to deliver natural gas into the central nozzle 30. The conduits 53 are arranged in a ring and equal number to the pilot lances 80 to communicate each conduit 53 with the pilot lances 80 to deliver natural gas independently into the pilot lances 80 (see arrows 93 in fig. 8 and 7). Natural gas is passed into central nozzle 30 in the direction indicated by arrow 92.

The burner body 50 may additionally have a plurality of pipes 215 for independently delivering natural gas to the fuel nozzles, and the pipes 215 are all connected to the gas delivery manifold 51. Of course, it is also possible to provide the fuel lance 80 with a natural gas carrying conduit 215 separately and to arrange the conduit 215 outside the burner body 50. Meanwhile, in the present embodiment, six pilot nozzles 80 are annularly arranged; preferably, the pilot lance 80 and each of the main-fuel lances 20 may be configured to be co-directed toward the central axis 200 of the central lance 30 to facilitate ignition of the main-fuel lances 20 by the pilot lance 80. In particular, the arrangement of the ring of pilot nozzles 80 is beneficial to ensuring better stability of the combustion of the main flame 213 ', preventing possible phenomena of ' misfire ' and ' deflagration ' in the ignition process of the low-nitrogen burner, and improving the working safety and combustion stability of the low-nitrogen burner.

Referring to fig. 2, 6-7, the main fuel lances 20 of this embodiment may be disposed around the outside of the recirculation sleeve 10 with the outer walls of the main fuel lances 20 not touching the outer side wall of the recirculation sleeve 10. To improve the efficiency of igniting primary fuel lance 20 injected gas 213, primary fuel lance 20 of the present embodiment is positioned against the outer sidewall of recirculation sleeve 10, as shown in FIG. 1. Wherein the main fuel lance 20 may be secured to the outside of the recirculation sleeve 10 by welding or the like. Specifically, one end of the diffuser cylinder 60 close to the recirculation sleeve 10 is formed with a radially-inwardly-constricted ring portion 61, and the air supply pipe 21 is located outside the diffuser cylinder 60 and vertically disposed on the mounting plate 52. The gas pipe 21 includes a first vertical section 2111 vertically disposed on the mounting plate 52 and close to the outside of the diffuser 60, an inclined section 2112 connected to the first vertical section 2111 and inclined in a direction matching the contraction direction of the reduced diameter ring portion 61, and a second vertical section 2113 connected to the inclined section 2112 and parallel to the longitudinal axis of the recirculation sleeve 10 (i.e., the central axis 200 of the central nozzle 30).

So, arrange through the outside that main fuel spray pipe 20 hugs closely recirculation sleeve 10, the peripheral main fuel spray pipe 20 of flame ignition that can be convenient for pilot burner 80 to ignite, it has the advantage that structural design is reasonable to reduce the temperature of central flame through setting up flame stabilizing disc 31, can effectively reduce the emission of heating power type nitrogen oxide.

In one embodiment, as shown in fig. 2, 4, 7 and 9, the free end 2100 of the air delivery pipe 21 transversely penetrates the main fuel nozzle 20, and the wall of the main fuel nozzle 20 is formed with a plurality of air outlet holes 211 annularly arranged around the free end 2100 of the air delivery pipe 21 (the air outlet holes 211 may be uniformly distributed around the wall of the main fuel nozzle 20). The main fuel nozzle 20 is internally provided with a first gas mixing channel 203 with the cross-sectional area S1, and the gas conveying pipe 21 is internally provided with a first gas channel 217 with the cross-sectional area. The recirculation sleeve 10 and the diffusion cylinder 60 are longitudinally separated, an annular first mixed gas inlet 62 is formed at the tail end of the recirculation sleeve 10, and a plurality of gas outlet holes 211 form a second mixed gas inlet positioned in front of the first mixed gas inlet 62. The ratio of the cross-sectional area S1 of the first gas mixing channel 203 to the cross-sectional area S2 of the first gas channel 217 is 3:1 to 2:1, and preferably, the ratio of S1 to S2 is 2.8: 1. The central nozzle 30 internally forms a second gas passage 307 of cross-sectional area S3 and the pilot nozzle 80 internally forms a third gas passage 803 of cross-sectional area S4.

The input end 2001 of the main fuel nozzle 20 is formed with a window 2002 through which the free end 2100 of the air delivery pipe passes, and the outer wall of the air delivery pipe 21 is attached to the edge of the window of the input end 2001 of the main fuel nozzle 20. Wherein the window 2002 has a radial dimension that is less than the radial cross-sectional dimension of the primary fuel lance 20. The air outlet 211 is located close to the air outlet 2101 of the air delivery tube free end 2100, and the air outlet 211 is located laterally forward or laterally rearward of the air outlet 2101 of the air delivery tube free end 2100, or the edge of the air outlet 2101 of the air delivery tube free end 2100 faces the air outlet 211. Due to the arrangement, the flue gas can conveniently enter the first gas mixing channel 203 from the gas outlet 211 and is mixed with the flue gas containing the reducing ion components, the combination probability of nitrogen molecules and oxygen molecules in the combustion chamber 400 in the combustion process of the main flame 213' is reduced, the combination probability of the nitrogen molecules and the oxygen molecules is fundamentally inhibited, and the content of thermal nitrogen oxides in the combustion chamber 400 is remarkably reduced.

The shape of the air outlet 211 is configured to be at least one of a circle, a rectangle, a polygon, etc., as long as the flue gas can enter the first gas mixing channel 203 of the main fuel nozzle 20 through the air outlet 211 to realize a flue gas mixing cycle, which is not limited to the range defined by the shape of the air outlet 211 in this embodiment.

In another embodiment, as described with reference to fig. 1 and 6, the main fuel nozzle 20 and the air pipe 21 are longitudinally and separately configured to form a fuel nozzle, and the second air mixing inlet is formed by longitudinally and separately forming the main fuel nozzle 20 and the air pipe 21.

It is understood that, in the low-nitrogen combustor of the present embodiment, the second gas mixing inlet formed by the plurality of gas outlets 211 disposed on the tube wall of the main fuel nozzle 20 (or the second gas mixing inlet formed by the longitudinal separation of the main fuel nozzle 20 and the gas delivery tube 21) realizes the circulation of the flue gas formed in the combustion chamber of the boiler during the fuel combustion process, so as to improve the utilization rate of the flue gas circulation. Meanwhile, by forming the annular first gas mixing inlet 62 at the tail end of the recirculation sleeve 10 and by means of the diffusion cylinder 60, the air flow rate is increased, the recycling rate of the flue gas is further increased, and the energy density of the fuel conveyed to the combustion chamber by the main fuel nozzle 20 is reduced by mixing the flue gas containing the reducing ion components into the first gas mixing channel.

In any of the above embodiments, the free end of the primary fuel lance 20 is disposed laterally forward of the opening of the inner barrel 40. The free end of the main fuel nozzle 20 forms an inclined surface 202 facing outward, and an included angle formed between the inclined surface 202 and the central axis of the central nozzle 30 is an acute angle to reduce the residence time of natural gas in a high temperature region, thereby suppressing the generation of nitrogen oxides. The free end of the primary fuel lance 20 is the end remote from the mounting plate 52. Preferably, by aligning and matching the end face of the free end of the main fuel lance 20 parallel to the radial cross-section of the main fuel lance, the stability of the main flame is improved, the emission of carbon monoxide CO is reduced, the emission of nitrogen oxides NOx is not affected, and at the same time, the emission of nitrogen oxides NOx at low load is improved. In the present embodiment, the inclined surface 202 forms an acute angle with the central axis 200 of the central nozzle 30, which means that the inclined surface 202 forms an acute angle with the central axis 200 with an extension away from the mounting plate 52.

As shown in FIG. 2, a heat-insulating cylinder 22 partially wrapping the air pipe 21 and the diffusion cylinder 60 can be arranged outside the diffusion cylinder 60, and the heat-insulating cylinder 22 is filled with a heat-insulating material 221. Specifically, the thermal insulation material 221 is made of asbestos rope and refractory clay by mixing.

In the present embodiment, six fuel lances are arranged annularly and equally spaced outside the recirculation sleeve 10. The number of fuel lances is not particularly limited, and may be increased or decreased as needed, and the six fuel lances consume a substantial portion of the fuel to form the main flame 213' (shown in fig. 7). The recirculation sleeve 10 and the diffusion cylinder 60 are longitudinally separated, a first annular mixed gas inlet 62 is formed at the tail end of the recirculation sleeve 10, and the fuel spray pipe forms a second mixed gas inlet which is positioned in front of the first mixed gas inlet 62. The mixed gas containing natural gas and flue gas returning from the second gas mixing inlet flows horizontally in the first gas mixing channel 203 as shown by the arrow 91.

The annular cavity 17 delivers fresh air into the second air mixing channel 19 under the action of the air inducing device 70, and sucks the returned flue gas through the first air mixing inlet 62. Specifically, the annular cavity 17 delivers 1M of air into the second air mixing channel 19³The fresh air can be sucked into the returned flue gas by the first gas mixing inlet 62 by about 0.5-1M³. Meanwhile, in the present embodiment, theA gas channel 217 for delivering 1M to the combustion chamber 400³The backflow flue gas can be sucked by the second gas mixing inlet in the process of natural gas by about 0.5-1M³. Fresh air blown into the combustion chamber 400 of the furnace by the air inducing device 70 is conveyed to the combustion chamber 400 through the annular cavity 18.

Flue gas (the oxygen content in the flue gas is 3-5%) in the combustion chamber 400 enters the first gas mixing channel 203 from the second gas mixing inlet along a flow path shown by an arrow 201 in fig. 1 or fig. 2 and 7. In the present embodiment, since a large amount of flue gas containing a reducing ion component is mixed in natural gas, the reducing ion includes carbon ions, hydrogen ions, and carbon monoxide. By mixing the flue gas containing the reductive ion components into the first gas mixing channel 203, the bonding probability of nitrogen molecules and oxygen molecules in the combustion chamber 400 of the main flame 213' in the combustion process is reduced, the bonding probability of the nitrogen molecules and the oxygen molecules is fundamentally inhibited, and the content of the thermal nitrogen oxides in the combustion chamber 400 is remarkably reduced; in addition, the energy density of the natural gas supplied from the first gas mixing passage 217 is reduced by mixing the flue gas containing the reducing ion component into the first gas mixing passage 203.

Meanwhile, in the present embodiment, the recirculation sleeve 10 is coaxially and nestingly disposed with the inner tube 40 to form the second air mixing passage 19 in a ring shape. The flue gas is blocked by the furnace wall 100 and forms a flow path shown by an arrow 209, so that the flue gas flows along the flow path shown by the arrow 301 and the arrow 209 again, and the flue gas flows back from the first gas mixing inlet 62 to the annular second gas mixing channel 19 for gas mixing treatment again, so as to reduce the oxygen content in the annular second gas mixing channel 19. The first gas mixing inlet 62 is circular. Arrow 95 is the flow path of the flue gas containing air and backflow. Through the technical scheme, the circulation utilization rate of the flue gas is improved, and the oxygen content of the mixed gas formed in the second gas mixing channel 19 by the fresh air conveyed from the annular cavity 17 to the second gas mixing channel 19 is reduced. Specifically, the oxygen content in the fresh air delivered from the annular cavity 17 to the second air mixing channel 19 can be reduced from 21% to 10-18%, and an "oxygen-poor region" is formed in the annular region of the second air mixing channel 19 far from the mounting plate 52 while the combustion stability of the main flame 213' in the combustion chamber 400 is ensured. As the inner barrel 40 delivers fresh air to the combustion chamber 400, an "oxygen rich zone" is formed at the opening of the inner barrel 40. Therefore, the flue gas and the flame in the end space of the main flame 213 ' flow back to the oxygen-rich area along the path shown by the arrow 97, thereby ensuring the full combustion of the natural gas, reducing the flame temperature of the main flame 213 ', and enabling the flame temperature of the main flame 213 ' to be uniform in the combustion chamber 400.

Through practical calculation, the low-nitrogen burner disclosed by the embodiment is used on a hearth forming the combustion chamber 400, and when the heat load in the combustion chamber 400 is less than 1200kw/m³When the discharge amount of nitrogen oxides is less than 28mg/m³。

Referring to fig. 1, 2 and 4, in the present embodiment, the flame stabilizing disc 31 is provided with flame stabilizing holes 312, and the flame stabilizing holes 312 are uniformly formed in the flame stabilizing disc 31 along the radial direction and are communicated with the annular cavity 18. To form a dense longitudinal flame 314 through the flame stabilizing holes 312. The central nozzle 30 extends over the end of the flame stabilizing disc 31 and is annularly provided with a plurality of transverse spray holes 311, so that transverse flames 315 can be formed through the transverse spray holes 311. The flame stabilizing disc 31 is arranged transversely recessed inside the inner barrel 40 and laterally abuts against the pilot lance 80 to sandwich the pilot lance 80 together with the inner barrel 40 by said flame stabilizing disc 31, the pilot lance 80 extending longitudinally over the flame stabilizing disc 31 but not in the longitudinal direction over the inner barrel 40. The function of the pilot lance 80 in this embodiment is to form a pilot flame 96 and, by this pilot flame 96, to pilot six fuel lances outside the recirculation sleeve 10, to form a ring of main flames 213'. The pilot nozzle 80 is attached to an inner wall surface 401 of the inner tube 40. As a rational modification of the present embodiment, the pilot nozzle 80 may be attached to the outer wall surface 402 of the inner tube 40.

It should be noted that, in the present embodiment, a circle of gaps 303 with a radial width equal to the outer diameter of the pilot nozzle 80 is still formed between the flame stabilizing disc 31 and the inner barrel 40, and the air blown from the air inducing device 70 can be horizontally injected into the combustion chamber 400 along the direction of the arrow 94 in fig. 4 to assist the combustion of the pilot nozzle 80 and ensure that the pilot flame 96 is continuously and stably combusted. The transversely recessed arrangement of the flame stabilizer 31 inside the inner barrel 40 not only facilitates the formation of a stable and short longitudinal flame 314 by the flame stabilizer 31, but also enables the formation of a stable longitudinal flame 314 in the "oxygen rich zone" at the opening of the inner barrel 40, and the pilot lance 80 is ignited by the longitudinal flame 314 to form an outwardly flared pilot flame 96 by the pilot lance 80, and facilitates the improvement of the stability of the combustion of the pilot flame 96, and finally the main flame 213 'is ignited by the pilot flame 96, thereby significantly improving the stability of the main flame 213', and enabling the temperature of the longitudinal flame 314 to be reduced, thereby significantly reducing the generation of nitrogen oxides in the "oxygen rich zone" near the flame stabilizer 31. The outer ring of fuel lances forms a stable combustion main flame 213 ' with the pilot flame 96 and forms a "lean oxygen zone" within the combustion chamber 400, and the main flame 213 ' forms a wide range of flame and heat cycles within the combustion chamber 400 to maintain stable combustion of the main flame 213 ', pilot flame 96 and central flame (i.e., longitudinal flame 314).

Meanwhile, the end of the central nozzle 30 can be configured as a central combustion head 32 which is connected in a plugging manner, and a circle of transverse injection holes 311 (shown in fig. 2) are distributed around the central combustion head 32; alternatively, the central burner head 32 may be omitted and a ring of transverse jet holes 311 (see fig. 4) may be provided directly at the end of the closed-end central nozzle 30.

Referring to fig. 7, the low-nitrogen burner further includes an ignition electrode 81 disposed adjacent to and parallel to the central nozzle 30, the ignition electrode 81 extending over the flame stabilization disk 31 and forming an ignition needle 811 bent radially inward so as to ignite natural gas flowing horizontally in the central nozzle 30 along arrow 92 through the ignition needle 811 to ignite the entire flame stabilization disk 31.

Specifically, the first gas mixing inlet 62 is divided into four fan-shaped flue gas suction inlets by four connecting plates 12, and is enclosed by the inner cylinder 40, the recirculation sleeve 10 and the connecting plates 12 to form a second gas mixing channel 19 with fan-shaped through holes at two ends. The mixed gas corresponding to the arrow 95 (the mixed gas includes the fresh air blown in from the induced draft device 70 and the flue gas returned from the first mixed gas inlet 62) is blown into the combustion chamber 400 and participates in combustion.

Meanwhile, in the embodiment, the sum of the cross sectional areas S2 of all the first gas channels 217 accounts for 70-90% of the total gas conveying amount of the gas conveying main pipe 51, the sum of the cross sectional areas S3 of all the second gas channels 307 accounts for 5-15% of the total gas conveying amount of the gas conveying main pipe 51, and the sum of the cross sectional areas S4 of all the third gas channels 803 accounts for 5-15% of the total gas conveying amount of the gas conveying main pipe 51. More preferably, the setting of the gas consumption ratio may be further defined as follows:

the sum of the cross-sectional areas S2 of all the first gas passages 217 accounts for 90% of the total gas delivery of the gas delivery manifold 51, the sum of the cross-sectional areas S3 of all the second gas passages 307 accounts for 5% of the total gas delivery of the gas delivery manifold 51, and the sum of the cross-sectional areas S4 of all the third gas passages 803 accounts for 5% of the total gas delivery of the gas delivery manifold 51. Through the setting of the gas consumption proportion, the continuous and stable combustion of the circle of main flames 213 'can be ensured, the flame temperature of the central flames can be reduced to reduce the generation amount of thermal nitrogen oxides, the combustion stability of the main flames 213', the transverse flames 315 and the longitudinal flames 314 can be ensured, and the problems that the traditional low-nitrogen combustor is easy to generate 'misfire' and 'deflagration' caused by insufficient natural gas combustion during combustion are solved.

As shown in fig. 2, 4 and 7, in the present embodiment, the thickness of the diffuser 60 is kept the same as a whole, and a radially-inwardly-constricted ring portion 61 is formed at one end of the diffuser 60 close to the recirculation sleeve 10 to raise the flow rate of air flowing through the annular cavity 17 formed between the inner barrel 40 and the diffuser 60 by the radially-constricted ring portion 61 and the inner barrel 40. Specifically, the outer wall of the reduced-diameter ring portion 61 not only can guide the flue gas corresponding to the flue gas flow path shown by the arrow 301, but also can collect and compress the air flow shown by the arrow 99 on the inner wall surface 611 of the reduced-diameter ring portion 61, so as to increase the flow velocity of the air flow shown by the arrow 99, prevent the air from being dissipated to the combustion chamber 400 from the opening of the annular second air mixing channel 19, and facilitate the formation of the mixed gas corresponding to the arrow 95.

In the present embodiment, in order to connect the recirculation sleeve 10 and the inner cylinder 40, a plurality of radially disposed connection plates 12 are disposed between the recirculation sleeve 10 and the inner cylinder 40, and the connection plates 12 extend to the outer wall surface of the reduced diameter ring portion 61 along the longitudinal extension direction of the recirculation sleeve 10. The annular second air mixing channel 19 is thus divided into four separate sub-channels 304 with sector-shaped cross-sections by providing four connecting plates 12 perpendicular to each other. The cross-sectional cut is perpendicular to the central axis 200.

Meanwhile, the four connecting plates 12 are arranged to further perform turbulence and segmentation on the mixed gas which flows through the second gas mixing channel 19 and is composed of the flue gas flowing back from the first gas mixing inlet 62 and the air conveyed by the air inducing device 70, so that the mixed gas can flow smoothly in the second gas mixing channel 19, and turbulence of the mixed gas in the second gas mixing channel 19 is prevented.

The low-nitrogen combustor disclosed by the embodiment combines the technical advantages of FIR (Fuel Inner recycle) and FGR (Fuel Gas recycle), and significantly improves the flue Gas circulation amount in the combustion chamber 400; while achieving stable combustion of the main flame 213', the pilot flame 96, and the center flame (i.e., the longitudinal flame 314). The low-nitrogen combustor can reduce the flame temperature of a combustion area, particularly can reduce the central flame temperature of an oxygen-enriched area, avoids forming a local high-temperature area, reduces the air excess coefficient in the whole combustion chamber 400, and can save the fuel consumption by about 3-5%.

The above list of details is only for the practical implementation of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention should be included in the scope of the present invention.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (9)

1. A low-nitrogen burner, comprising:

mounting a plate;

the diffusion tube is vertically arranged on the mounting plate, an inner tube which longitudinally protrudes out of the diffusion tube is embedded in the diffusion tube, and a plurality of ignition spray tubes are annularly distributed on the inner side of the inner tube;

the recycling sleeve is sleeved outside the inner barrel and longitudinally separated from the diffusion barrel, a plurality of fuel spray pipes are annularly distributed on the outer side of the recycling sleeve, and the free end of the recycling sleeve forms an annular contraction part which contracts inwards in the radial direction; and the number of the first and second groups,

the flame stabilizing disc is vertically penetrated with a central spray pipe;

the fuel spray pipe consists of a main fuel spray pipe and a gas transmission pipe connected with the main fuel spray pipe, and the free end of the main fuel spray pipe is formed in front of the side of the free end of the inner cylinder;

the tail end of the recirculation sleeve forms an annular first gas mixing inlet, and a second gas mixing inlet located in front of the first gas mixing inlet side is formed at the joint of the main fuel spray pipe and the gas conveying pipe.

2. The low-nitrogen burner of claim 1,

the main fuel nozzle is arranged to fit against an outer sidewall of the recirculation sleeve.

3. The low-nitrogen burner of claim 2,

one end of the diffusion cylinder, which is close to the recirculation sleeve, is provided with a radial contracted ring part which is contracted inwards in the radial direction, and the gas conveying pipe is positioned outside the diffusion cylinder and vertically arranged on the mounting plate;

the gas conveying pipe is composed of a first vertical section which is vertically arranged on the mounting plate and is close to the outer side of the diffusion cylinder, an inclined section which is connected with the first vertical section and the inclined direction of which is matched with the contraction direction of the reducing ring part, and a second vertical section which is connected with the inclined section and is parallel to the longitudinal axis direction of the recirculation sleeve.

4. The low-nitrogen burner as claimed in claim 1, wherein the free end of the gas pipe longitudinally penetrates through the main fuel nozzle, and a plurality of gas outlets are formed on the wall of the main fuel nozzle and annularly arranged around the free end of the gas pipe, and the plurality of gas outlets form a second gas mixing inlet in front of the first gas mixing inlet.

5. The low-nitrogen burner of claim 4,

a window for the free end of the gas transmission pipe to penetrate through is formed at the input end of the main fuel spray pipe, and the outer pipe wall of the gas transmission pipe is attached to the edge of the window at the input end of the main fuel spray pipe;

the size of the radial surface of the window is smaller than the size of the radial section of the main fuel spray pipe, and the plurality of air outlets are uniformly distributed on the pipe wall of the main fuel spray pipe in a surrounding mode.

6. The low-nitrogen burner of claim 4,

the free end of main fuel spray pipe forms the inclined plane towards the outside, the contained angle that inclined plane and the axis of central spray pipe formed is the acute angle.

7. The low-nitrogen burner of claim 1,

the second gas mixing inlet is formed by longitudinally separating a main fuel spray pipe and a gas conveying pipe, and the end face of the free end of the main fuel spray pipe is parallel to and matched with the transverse section of the main fuel spray pipe.

8. The low-nitrogen burner of claim 7,

the free end of the main fuel nozzle is disposed in front of the opening of the inner cylinder.

9. The low-nitrogen burner of claim 3,

a heat-insulating cylinder which partially wraps the gas conveying pipe and the diffusion cylinder is arranged outside the diffusion cylinder, and heat-insulating materials are filled in the heat-insulating cylinder;

and a plurality of connecting plates which are arranged in the radial direction are arranged between the recycling sleeve and the inner barrel, and the connecting plates extend to the outer wall surface of the radial shrinkage ring part along the longitudinal extension direction of the recycling sleeve.

Images