CN109931605A - A kind of outside dense interior light turbulent burner of diameter of multistage air distribution - Google Patents

Abstract

A kind of outside dense interior light turbulent burner of diameter of multistage air distribution, it is related to a kind of burner, the present invention is to solve existing burner since pulverized coal concentrator enrichment factor is low, it is unfavorable for the stability of reduction and the burning of NOx, the problem of stability of burner recirculating zone is poor, cannot be well adapted for multi items burning of coal.The present invention includes central tube, primary air piping, inner second air pipe, middle secondary air channel, outer second air pipe, pulverized coal concentrator and flow spoiler；Central tube, primary air piping, inner second air pipe, middle secondary air channel and outer second air pipe are successively set in together from inside to outside, central tube, primary air piping, inner second air pipe, middle secondary air channel and outer second air pipe outlet end be successively arranged First air flaring, inner second air flaring, the flaring of middle Secondary Air and outer second air flaring；Pulverized coal concentrator and flow equalizing ring are provided in First air air hose.The present invention reduces nitrogen oxides, and the kindling ability of burner is improved, and improves the steady fuel efficiency fruit of burner.The present invention is suitable for boiler.

Description

A radially outer rich swirl burner with inner thin air distribution in multiple stages

technical field

The invention relates to a burner, in particular to a multi-stage air distribution swirl burner with a radial outer rich and an inner lean swirl burner.

Background technique

The traditional boiler swirl pulverized coal burner is easy to form an oxygen-enriched combustion zone due to the strong airflow disturbance in the early stage of combustion and the rapid mixing of the secondary air. Moreover, the flame is short, the heat release is concentrated, and the flame temperature is high, so the NOx emission is very high. Therefore, there have been many low NOx swirl burners, which divide the secondary air into multiple stages, send the pulverized coal into the furnace through the primary air, and prolong the combustion time of the pulverized coal through the staged combustion of the multistage air. The air classification is to To achieve the purpose of delaying mixing and controlling the combustion process, only the amount of air required to maintain stable ignition and volatile combustion is fed into the primary combustion zone to form a dense phase core flame and reduce the peak temperature of the flame; due to the delayed mixing of the secondary air, the formation of The reduction zone can not only reduce the generation of NOx but also reduce part of _NOx .

The current low NOx outer rich and inner thin swirl burner, because the pulverized coal concentrator mostly adopts the Venturi pulverized coal concentrator, after the primary air pulverized coal is concentrated by the concentrator, it is distributed in the radial direction with the outer rich and the inner thin. That is, the concentration of pulverized coal in the inner wall area of the primary air duct is high, and the concentration of pulverized coal in the outer wall area of the central air duct is low, which realizes the staged combustion of fuel, which can effectively reduce the generation of nitrogen oxides and improve the ignition stability of pulverized coal. The rate is low, generally between 60% and 75%, which is not conducive to the reduction of NOx and the stability of combustion, and the stability of the recirculation zone of the burner is poor, so it can only be adapted to bituminous coal and lignite with high volatile content. Incomplete combustion occurs.

SUMMARY OF THE INVENTION

In order to solve the problem that the existing swirl burner is not conducive to the reduction of NOx and the stability of combustion due to the low concentration rate of the pulverized coal concentrator, and the stability of the recirculation zone of the burner is poor, it can only adapt to coal with high volatile content, and cannot be very It is well adapted to the problem of burning various types of coal, and provides a swirl burner with a radially outer rich and inner thin swirl burner with multi-stage air distribution.

The technical scheme that the present invention takes for solving the above-mentioned technical problems is:

Option 1: A multi-stage air distribution radially rich swirl burner with inner thin air includes a central pipe, a primary air duct, an inner secondary air duct, a middle and secondary air duct, an outer secondary air duct, and an inner swirl. cyclone, external cyclone, secondary air box, spoiler, pulverized coal concentrator and equalizing ring;

The central pipe, the primary air duct, the inner secondary air duct, the middle and secondary air ducts and the outer secondary air ducts are assembled together from the inside to the outside, and the adjacent two form the primary air channel from the inside to the outside. The primary air duct, the inner secondary air duct, the middle secondary air duct and the outer secondary air duct are provided with primary air flaring, The inner secondary air flaring, the middle secondary air flaring and the outer secondary air flaring, the spoiler is arranged on the inner wall of the outlet end of the primary air duct, the inner cyclone is arranged in the middle and secondary air channel, and the outer swirl The flow device is arranged in the outer secondary air channel;

The pulverized coal concentrator includes a support plate and N concentration rings, where N is an integer of 2-5;

The diameters of the N concentrating rings increase in turn along the flow direction of the primary air pulverized coal, and the two adjacent concentrating rings are arranged at a certain distance. On the outer wall of the , N concentration rings are arranged on one side adjacent to the outlet of the central pipe;

The equalizing ring is arranged on the inner wall of the primary air duct, and the equalizing ring is arranged adjacent to one side of the concentrating ring with a larger diameter.

Further, the spoiler is composed of M trapezoidal plates with the plate surfaces on the same plane, M is an integer of 8-16, and the M trapezoidal plates are evenly arranged at the outlet end of the inner wall of the primary air duct, and two adjacent ones. The trapezoidal plates are arranged with a certain gap, and the length of each trapezoidal plate is 0.1 to 0.4 times the distance from the outer wall of the central pipe to the inner wall of the primary air duct.

Option 2: A radially outer rich and inner thin swirl burner with multi-stage air distribution includes a central pipe, a primary air duct, an inner secondary air duct, an outer secondary air duct, an inner swirler, and an outer swirler. , secondary air box, spoiler, pulverized coal concentrator, equalizing ring and spacer cylinder;

The central pipe, the primary air duct, the spacer tube, the inner secondary air duct and the outer secondary air duct are assembled together from the inside to the outside. A primary air channel is formed between the central pipe and the primary air duct. The two adjacent to the outer secondary air duct form an inner secondary air channel and an outer secondary air channel in turn from the inside to the outside. The outlet ends of the inner secondary air duct and the outer secondary air duct are provided with primary air flaring, inner secondary air flaring and outer secondary air flaring in one-to-one correspondence, and the spoiler is arranged on the inner wall of the outlet end of the primary air duct On the upper side, the inner cyclone is arranged in the inner secondary air channel, and the outer cyclone is arranged in the outer secondary air channel;

The pulverized coal concentrator includes a support plate and N concentration rings, where N is an integer of 2-5;

The diameters of the N concentrating rings increase in turn along the flow direction of the primary air pulverized coal, and there is a certain distance between the two adjacent concentrating rings. On the outer wall, N concentration rings are arranged on one side adjacent to the outlet of the central pipe;

The equalizing ring is arranged on the inner wall of the primary air duct, and the equalizing ring is arranged adjacent to one side of the concentrating ring with a larger diameter.

Compared with the prior art, the present invention has the following beneficial effects:

1. The burner system of the present invention has low resistance, the total secondary air resistance does not exceed 800Pa, saves the power consumption of the fan, and the present invention can well maintain the combustion stability under all loads, and the nozzle does not produce coking.

2. Compared with the prior art, the present invention realizes the separation of the concentration of the primary air pulverized coal through a new type of pulverized coal concentrator and an equalizing ring, and the separation efficiency can reach 90%, that is, the fuel of the primary air pulverized coal is realized. Staged combustion can also reduce the wind speed of the primary air near the primary air duct wall, effectively reducing the erosion of the primary air duct wall by the primary air pulverized coal mixture and prolonging the service life of the equipment. The primary air of the present invention carries the pulverized coal into the primary air channel, as shown in Figure 12 and Figure 14, under the concentrating action of the pulverized coal concentration device, the pulverized coal in the primary air is divided into two parts, the thick and the light, and the dense and thin parts are formed near the inner pipe wall area of the primary air. The pulverized coal area is close to the outer surface of the central air duct to form a thin pulverized coal area, and the pulverized coal concentration ratio is between 75-90%. The pulverized coal is concentrated near the inner surface of the primary air duct and injected into the furnace to realize the staged combustion of pulverized coal, increase the amount of pulverized coal in the middle high-temperature recirculation area, strengthen the reducing atmosphere in the central recirculation area, and prolong the residence time of the pulverized coal in the recirculation area. Suppresses the formation of fuel-type nitrogen oxides.

3. The present invention divides the main combustion air into three levels: inner secondary air, middle secondary air and outer secondary air to increase the air grading degree. While the outlet forms a stable central recirculation zone, there is a low-speed zone between the primary air and the secondary air, which delays the mixing of the primary air and the secondary air, because the inner secondary air is a DC secondary air and the air volume Small, low wind speed, so its penetrating ability and ability to entrain primary wind are weak, it will not entrain primary wind prematurely, increase the distance between the primary wind and the peripheral mainstream secondary wind, and delay the relationship between the primary wind and the cyclone. The mixing of the secondary air and the secondary air strengthens the reducing atmosphere in the central recirculation zone and suppresses the formation of nitrogen oxides. At the same time, the secondary air and the secondary air pass through the inner and outer cyclones to form a cyclone. It is injected into the furnace at a high speed, and its function is to complete the combustion of unburned carbon in the area far from the burner outlet, and to ensure that the near-combustion area forms a stable recirculation area.

4. The present invention divides the main combustion air into inner secondary air and outer secondary air for graded combustion. At the same time, a spacer tube is set between the primary air duct and the inner secondary air duct, as shown in Figure 12, at the outlet of the present invention. A stable central recirculation zone, and at the same time, there is a vulgar zone between the primary air and the secondary air, which delays the mixing of the primary air and the secondary air because there is a spacer tube between the primary air and the inner secondary air. The primary air mixture at the outlet end of the present invention and the secondary air are injected at intervals, which increases the distance between the primary air and the peripheral mainstream secondary air, delays the mixing of the primary air and the swirl secondary air, and strengthens the central backflow. The reducing atmosphere in the zone inhibits the formation of nitrogen oxides. At the same time, both the inner secondary air and the outer secondary air pass through the inner cyclone and the outer cyclone to form a swirling wind that is injected into the furnace, and the speed is high, and its function is to complete the combustion of the unburned carbon in the area far from the outlet of the present invention. , and to ensure that the near-natural region forms a stable reflow region.

5. In the present invention, a spoiler is arranged on the inner surface of the outlet end of the primary air duct. The spoiler is composed of M trapezoidal plates and is evenly arranged on the circumference of the primary air duct, where M is an integer of 8-16; The length is 0.1 to 0.4 times of the distance between the central air duct and the primary air duct. Under the combined action, it can be seen from the schematic diagram of the concentration distribution of primary air pulverized coal in Figure 12 that under the action of the spoiler , in the circumferential direction, there is a distribution pattern of thick and light coal powder and a thin coal powder, which improves the local coal powder concentration in the primary air outlet section and strengthens the coal powder classification combustion, which is especially beneficial to improve the burner's stable combustion performance and Reduce the formation of nitrogen oxides. At the same time, due to the existence of the spoiler, when the pulverized coal air flows around the spoiler, a small swirl circle is formed on its circumference, which is attached to the root of the high temperature return area. characteristics to ensure the stable combustion characteristics of the burner.

Sixth, the present invention sets flaring in the secondary air and the outer secondary air, strengthens the swirl intensity of the secondary air of the inner swirl and the secondary air of the outer swirl, and delays the mixing of the secondary air and the primary air , prolonging the residence time of pulverized coal in the central recirculation zone of the reducing atmosphere, so as to form an oxygen-deficient environment in the area near the burner, which is conducive to the reduction of NOx and reduces the generation of nitrogen oxides.

7. Under the combined action of the unique pulverized coal concentration device, flared structure, and unique air volume distribution of the present invention, as shown in Figures 10 to 14, the primary air powder jet area at the burner outlet forms a stable central recirculation zone. The central recirculation area can suck the primary air that is thick on the outside and thin on the inside into the recirculation area, and bring the high-temperature flue gas back to the area near the burner to heat the primary air powder, promote the ignition of the pulverized coal, ensure the stability of the flame, and achieve different loads. Stable combustion, the high temperature flue gas brought back has low oxygen content, making the recirculation zone in an oxygen-deficient environment and inhibiting the formation of nitrogen oxides.

8. The concentration rate of the pulverized coal concentration device of the present invention is more than 90%, which further improves the reduction of NOx and the stability of combustion. The unique pulverized coal concentration device of the present invention and the specific flare combination structure can better Adapt to the combustion of different types of coal, so that the stability of combustion is better.

Description of drawings

Fig. 1 is the overall structure diagram of scheme one of the present invention;

Fig. 2 is a partial enlarged view at I of Fig. 1, and the arrow direction in the figure is the direction of pulverized coal conveying;

Fig. 3 is the schematic diagram of spoiler 7;

Fig. 4 is the partial enlarged view of II place of Fig. 1;

Fig. 5 is the partial schematic diagram of the first scheme at the outlet in Fig. 1;

Fig. 6 is the partial schematic diagram of the second scheme at the outlet in Fig. 1;

Fig. 7 is the overall structure diagram of scheme two of the present invention;

Fig. 8 is the partial schematic diagram of the first scheme at the outlet in Fig. 7;

Fig. 9 is the partial schematic diagram of the second scheme at the outlet in Fig. 7;

10 is a schematic diagram of the outlet cold flow field recirculation zone and expansion angle of the present invention;

Fig. 11 is an outlet velocity vector numerical simulation distribution diagram of the present invention;

Fig. 12 is the numerical simulation cloud map of outlet velocity distribution of the present invention;

Figure 13 is a cloud map of the distribution of coal powder concentration in the primary air duct of the present invention;

Fig. 14 is the cloud map of the coal powder concentration distribution at the primary air outlet end of the present invention;

In Figures 1 and 7, the arrows in the primary air duct 2 are the conveying directions of the pulverized coal, and the arrows at the inner secondary air duct 3, the middle secondary air duct 4 and the outer secondary air duct 5 are the air inlet directions.

Detailed ways

Embodiment 1: This embodiment will be described with reference to FIGS. 1 to 4 . In this embodiment, a radially outer rich and inner thin swirl burner with multi-stage air distribution includes a central pipe 1 , a primary air pipe 2 , an inner two Secondary air duct 3, middle and secondary air duct 4, outer secondary air duct 5, inner cyclone 13, outer cyclone 14, secondary air box 15, spoiler 7, pulverized coal concentrator 6 and equalizing ring 8;

The central pipe 1, the primary air duct 2, the inner secondary air duct 3, the middle and secondary air duct 4 and the outer secondary air duct 5 are assembled together from the inside to the outside in order, and the adjacent two are formed one time from the inside to the outside. The air passage, the inner secondary air passage, the middle secondary air passage and the outer secondary air passage, the outlet ends of the primary air duct 2, the inner secondary air duct 3, the middle secondary air duct 4 and the outer secondary air duct 5. A primary air flaring 9, an inner secondary air flaring 10, a middle and secondary air flaring 11 and an outer secondary air flaring 12 are correspondingly provided, and the spoiler 7 is arranged on the inner wall of the outlet end of the primary air duct 2, The inner cyclone 13 is arranged in the secondary air channel, and the outer cyclone 14 is arranged in the outer secondary air channel;

The pulverized coal concentrator 6 includes a support plate 6-1 and N concentration rings 6-2, where N is an integer of 2-5;

The diameters of the N concentration rings 6-2 increase sequentially along the flow direction of the primary air pulverized coal, and the two adjacent concentration rings 6-2 are arranged at a certain distance, and the N concentration rings 6-2 pass through the support plate 6-1 Fixed together, the support plate 6-1 is fixed on the outer wall of the central pipe 1, and the N concentrating rings 6-2 are arranged on one side adjacent to the outlet of the central pipe 1;

The equalizing ring 8 is disposed on the inner wall of the primary air duct 2, and the equalizing ring 8 is disposed adjacent to one side of the concentrating ring 6-2 with a larger diameter.

Preferably, the outer cyclone 14 is installed in the secondary air box 15 , and the horizontal section of the primary air duct 2 and the horizontal section of the outer secondary air duct 5 are welded on the secondary air box 15 respectively.

The pulverized coal concentrator 6 includes a support plate 6-1 and N concentration rings 6-2, where N is an integer of 2-5;

The diameters of the N concentration rings 6-2 increase sequentially along the flow direction of the primary air pulverized coal, and there is a certain distance between two adjacent concentration rings 6-2. The N concentration rings 6-2 are fixed by the support plate 6-1. Connected together, the support plate 6-1 is fixed on the outer wall of the central pipe 1, and N concentrating rings 6-2 are arranged on one side adjacent to the outlet of the central pipe 1.

Preferably, a stainless steel jacket wear-resistant ceramic structure is used in the concentration ring 6-2 to improve the wear resistance of the concentration ring and increase the service life of the concentration ring.

Adjustment dampers are provided at the entrances of the inner secondary air duct 3, the middle secondary air duct 4 and the outer secondary air duct 5. By adjusting the size of the respective dampers, the size and strength of the central return area can be adjusted to adapt to different coals. According to the requirements of species, air volume and load, the adaptability of coal types of the burner is increased.

As shown in FIG. 13 , in this embodiment, the primary air-pulverized coal mixture is gradually concentrated under the action of the pulverized coal concentrator 6, and the pulverized coal air flow is divided into two parts: thick and thin parts, and the area close to the inner wall of the primary air duct forms a dense pulverized coal area, which is close to the central air duct. The outer surface area of the tube forms a thin pulverized coal area, and the concentration distribution of pulverized coal is dense outside and thin in the radial direction, which realizes the staged combustion of pulverized coal, increases the amount of pulverized coal in the middle high-temperature recirculation area, reduces the ignition heat of pulverized coal and prolongs the time of pulverized coal. The residence time in the recirculation zone enhances the reducing atmosphere in the central recirculation zone and inhibits the formation of nitrogen oxides.

The present invention divides the secondary air into inner secondary air, middle secondary air and outer secondary air, which increases the degree of air classification in the radial direction of the present invention, and the inner secondary air is a straight-through air with a small air volume. , at the same time add an inner secondary air flare, as shown in Figure 12, the distribution diagram of the burner outlet velocity nephogram, because this secondary air is a straight-through wind with a small air volume and a low wind speed, its penetration ability and entrainment ability are weak, and it is not It will prematurely entrain the primary air, increase the distance between the primary air and the swirl secondary air, delay the mixing of the primary air pulverized coal mixture and the peripheral swirl secondary air, strengthen the reducing atmosphere in the central recirculation area, and suppress the The formation of nitrogen oxides in the initial stage of combustion.

As shown in Fig. 10-Fig. 14, through the burner cold state modeling experiment and numerical simulation calculation, it is shown that a stable central recirculation zone is formed in the outlet area of the present invention. This recirculation zone is stable and has a good recirculation effect. The primary air is sucked into the recirculation zone, and the high-temperature flue gas on the outside is sucked back to the vicinity of the burner outlet to heat the primary air pulverized coal, promote the ignition of the pulverized coal, and maintain the flame stability. If the amount is low, the central recirculation area of the primary air outlet area is in an oxygen-deficient state, forming a reducing atmosphere and reducing the generation of nitrogen oxides.

Specific embodiment 2: This embodiment will be described with reference to FIG. 2. In this embodiment, the N concentrating rings 6-2 are all conical rings, and the tapers of the N concentrating rings 6-2 are all equal. The included angle δ between the bus bar and the center line of the central pipe 1 is 20° to 40°.

Other components and connection relationships are the same as in the first embodiment.

Specific Embodiment 3: This embodiment will be described with reference to FIG. 1 , FIG. 5 and FIG. 6 . The flow equalization ring 8 in this embodiment is provided at the edge of the primary air duct 2 between the primary air flare 9 and the pulverized coal concentrator 6 . On the inner pipe wall, the distance Ls from the end of the flow equalizing ring 8 adjacent to the primary air flaring 9 to the end of the primary air flaring 9 is 4~4 of the distance S1 from the outer wall of the central pipe 1 to the inner wall of the primary air duct 2 . 8 times, the thickness Hs of the equalizing ring 8 is 0.04-0.1 times the distance S1 from the outer wall of the central pipe 1 to the inner wall of the primary air duct 2 .

Other compositions and connection modes are the same as those in the second embodiment.

Specific Embodiment 4: This embodiment will be described with reference to FIG. 3 . The spoiler 7 in this embodiment is composed of M trapezoidal plates whose surfaces are on the same plane, where M is an integer from 8 to 16, and the M trapezoidal plates are evenly arranged At the outlet end of the inner wall of the primary air duct 2, and two adjacent trapezoidal plates are arranged with a certain gap, the height S of each trapezoidal plate is 0.1 to 0.4 times the distance S1 from the outer wall of the central pipe 1 to the inner wall of the primary air duct 2. .

As shown in Figure 13, the analysis by numerical calculation shows that adding the spoiler 7, the primary air thick pulverized coal is under the action of the spoiler 7, in the circumferential direction, there is a thick and light coal powder and a thin coal powder. The distribution mode increases the local coal powder concentration in the primary air outlet section and strengthens the coal powder staging combustion, which is especially beneficial to improve the burner's stable combustion performance and reduce the generation of nitrogen oxides. At the same time, due to the existence of the spoiler 7, when the pulverized coal gas flows around the spoiler 7, a small swirl circle is formed around its circumference, which is attached to the root of the high-temperature recirculation zone. Powder ignition characteristics to ensure stable combustion characteristics of the burner.

Other components and connection relationships are the same as in the third embodiment.

Embodiment 5: The present embodiment will be described with reference to FIG. 5 . In this embodiment, the expansion angle β of the primary air flaring 9 is in the range of 15° to 25°, and the expansion angle γ of the secondary air flaring 11 is in the range of 20°. °～25°, the expansion angle θ of the outer secondary air flare 12 ranges from 20° to 25°, and the expansion angle υ of the inner secondary air flare 10 ranges from 20° to 25°.

As shown in Fig. 10-Fig. 12, it can be seen from numerical calculation and burner cold-state modeling experiment that a stable recirculation zone can be formed in the burner outlet area by using the above-mentioned flare combinations of different angles. For different furnace forms, choose different flaring angle combinations to achieve the best combustion effect, reduce the formation of nitrogen oxides, and reduce the high temperature corrosion of the water wall. If each flare angle is too large, the expansion angle of the airflow will increase, forming an open recirculation zone, resulting in unstable combustion and coking of the water wall. If the area is too small, it is not conducive to the stable combustion of pulverized coal.

In this embodiment, the secondary air flaring 11 and the primary air flaring 9 delay the mixing of the primary air powder and the secondary air, prolong the residence time of the coal powder in the reducing atmosphere, and reduce the generation of nitrogen oxides.

Other components and connection relationships are the same as in the fourth embodiment.

Embodiment 6: This embodiment will be described with reference to FIG. 5 . In this embodiment, the end of the inner secondary air flaring 10 , the end of the secondary air flaring 11 and the end of the primary air flaring 9 are flat. All settings.

Other components and connection relationships are the same as in the fifth embodiment.

Embodiment 7: This embodiment will be described with reference to FIG. 5 . The length L4 of the primary air flaring 9, the length L3 of the inner secondary air flaring 10 and the length L2 of the intermediate secondary air flaring 11 in this embodiment are equal The length L4 of the primary air flaring 9 is 0.4 to 0.7 times the length L1 of the outer secondary air flaring 12 .

The primary air-powder mixture coming out of the primary air nozzle is first premixed with the central air flow, and then enters the outer secondary air flared opening to be premixed with the inner straight air, and then sprayed into the furnace together with the secondary air and the outer secondary air flow. The addition of two premixing sections helps to form a stable central recirculation zone in the burner outlet area, prolongs the residence time of primary air pulverized coal in the central recirculation zone, enables stable combustion of pulverized coal and effectively inhibits the formation of nitrogen oxides.

Other components and connection relationships are the same as in the sixth embodiment.

Embodiment 8: This embodiment will be described with reference to FIG. 6 . The length L3 of the inner secondary air flaring 10 in this embodiment is equal to the length L2 of the middle and secondary air flaring 11 ; the inner secondary air flaring The length L3 of the 10 is 0.6-0.8 times the length L1 of the outer secondary air flaring 12 ; the length L4 of the primary air flaring 9 is 0.5-0.7 times the length L3 of the inner secondary air flaring 10 .

In this embodiment, by adding three premixing sections, the mixing of the primary air-powder mixture and the secondary air is further delayed, and the swirl intensity of the secondary air is enhanced. It helps to form a stable central recirculation zone in the burner outlet area, prolongs the residence time of the primary air pulverized coal in the central recirculation zone, makes the pulverized coal burn stably and effectively inhibits the formation of nitrogen oxides, and is suitable for sub-bituminous coal, lean coal and anthracite.

Other components and connection relationships are the same as in the sixth embodiment.

Embodiment 9: This embodiment will be described with reference to FIG. 7 . In this embodiment, a radially outer rich and inner thin swirl burner with multi-stage air distribution includes a central pipe 1 , a primary air duct 2 , and an inner secondary air duct. 3. The outer secondary air duct 5, the inner cyclone 13, the outer cyclone 14, the secondary air bellows 15, the spoiler 7, the pulverized coal concentrator 6, the equalizing ring 8 and the spacer cylinder 16;

The central pipe 1, the primary air duct 2, the spacer 16, the inner secondary air duct 3 and the outer secondary air duct 5 are assembled together from the inside to the outside. The cylinder 16, the inner secondary air duct 3 and the outer secondary air duct 5 are adjacent to each other to form an inner secondary air passage and an outer secondary air passage from the inside to the outside. The pipe 2 is fixedly connected to form a closed space, and the outlet ends of the primary air duct 2, the inner secondary air duct 3 and the outer secondary air duct 5 are provided with a primary air flaring 9, an inner secondary air flaring 10 and an outer secondary air duct 5 in one-to-one correspondence. The secondary air flare 12, the spoiler 7 is arranged on the inner wall of the outlet end of the primary air duct 2, the inner cyclone 13 is arranged in the inner secondary air channel, and the outer cyclone 14 is arranged in the outer secondary air channel;

The pulverized coal concentrator 6 includes a support plate 6-1 and N concentration rings 6-2, where N is an integer of 2-5;

The diameters of the N concentration rings 6-2 increase sequentially along the flow direction of the primary air pulverized coal, and the two adjacent concentration rings 6-2 are arranged at a certain distance, and the N concentration rings 6-2 pass through the support plate 6-1 Fixed together, the support plate 6-1 is fixed on the outer wall of the central pipe 1, and the N concentrating rings 6-2 are arranged on one side adjacent to the outlet of the central pipe 1;

The equalizing ring 8 is disposed on the inner wall of the primary air duct 2, and the equalizing ring 8 is disposed adjacent to one side of the concentrating ring 6-2 with a larger diameter.

Preferably, the outer cyclone 14 is installed in the secondary air box 15 , and the horizontal section of the primary air duct 2 and the horizontal section of the outer secondary air duct 5 are welded on the secondary air box 15 respectively.

Other compositions and connection relationships are the same as in the second, third or fourth embodiment.

Embodiment 10: This embodiment will be described with reference to FIG. 7 . The thickness of the spacer tube 16 in this embodiment is 0.05-0.4 times the distance S1 from the outer wall of the central pipe 1 to the inner wall of the primary air duct 2 .

Other compositions and connection relationships are the same as in the ninth embodiment.

Embodiment 11: The present embodiment will be described with reference to FIG. 7 . In this embodiment, the expansion angle β of the primary air flaring 9 is in the range of 10° to 20°, and the expansion angle θ of the outer secondary air flaring 12 is in the range of 20°～25°, the expansion angle υ of the inner secondary air flaring 10 is in the range of 20°～25°.

Other compositions and connection relationships are the same as in the ninth embodiment.

Embodiment 12: This embodiment will be described with reference to FIG. 8 . The end of the inner secondary air flaring 10 and the end of the primary air flaring 9 are arranged flush with each other in this embodiment.

Other compositions and connection relationships are the same as in the ninth embodiment.

Specific Embodiment Thirteen: This embodiment will be described with reference to FIG. 8 . The length L4 of the primary air flaring 9 in this embodiment is equal to the length L3 of the inner secondary air flaring 10 ; the length L4 of the primary air flaring 9 is The length L1 of the outer secondary air flare 12 is 0.4 to 0.7 times.

Other compositions and connection relationships are the same as those in the twelfth embodiment.

Specific Embodiment Fourteen: This embodiment will be described with reference to FIG. 9 . In this embodiment, the length L3 of the inner secondary air flaring 10 is 0.6 to 0.8 times the length L1 of the outer secondary air flaring 12 ; the primary air flaring 9 The length L4 is 0.5 to 0.7 times the length L3 of the inner secondary air flare 10 .

Other compositions and connection relationships are the same as in the ninth, tenth or eleventh embodiment.

The two types of burners of the present invention are applied to the HG-1913/25.4-PM8 boiler: when coal is used, the nitrogen oxide emissions are as follows:

1. When burning bituminous coal, Vdaf=26.35%, Aar=22.65%, Mt=10.23%, Qnet, ar=21.18Mj/kg (wherein Vdaf is dry ashless volatile matter, Aar is the ash content parameter of received base, Mt is the total moisture parameter, Qnet,ar is the low-level calorific value of the received base), and the emission of nitrogen oxides at the tail of the boiler after all 24 burners adopt the novel burner of the present invention is less than 210 mg/m ³ .

2. When using a mixture of 50% lean coal and 50% bituminous coal: the chemical analysis of the lean coal is as follows: Vdaf=19.9%, Aar=32.65%, Mt=7.2%, Qnet,ar=19.13Mj/kg, where The chemical analysis of the bituminous coal is as follows: Vdaf=26.35%, Aar=22.65%, Mt=10.23%, Qnet,ar=21.18Mj/kg, the emission of nitrogen oxides from the tail of the boiler after all 24 burners adopt the novel burner of the present invention The amount is below 270mg/m3.

The above experimental data show that the present invention can ensure that nitrogen oxides meet the standard when burning different coal qualities, the emission of nitrogen oxides after combustion meets the relevant regulations, and can be used for burning more coal types.

The working principle of scheme 1 of the present invention is as follows: the primary air-powder mixture enters the primary air duct 2 through the powder feeding pipeline, and a pulverized coal concentrator 6 is arranged in the primary air duct of the burner. The diameter increases in turn along the flow direction of the primary air. The primary air powder mixture is divided into two parts after passing through the pulverized coal concentrator 6. The area close to the inner wall of the primary air duct 2 forms a dense coal powder area, and the area close to the outer surface of the central air duct 1 forms a thin coal area. At the same time, due to the existence of the equalizing ring 8, the wind speed in the inner wall area of the primary air duct 2 is reduced, the erosion of the primary air duct 2 by the primary air pulverized coal mixture is effectively reduced, and the service life of the equipment is prolonged. With the existence of the spoiler 7, the primary air pulverized coal is distributed at an interval of one thick and one thin in the circumferential direction at the outlet end of the primary air duct 2. Realize the staged combustion of pulverized coal fuel in the radial and circumferential directions, increase the amount of fuel in the central recirculation zone, reduce the generation of nitrogen oxides, improve the stable combustion ability of the burner, and form a small swirl circle around the spoiler, attaching At the root of the high-temperature recirculation zone, in the small vortex zone, the pulverized coal is easy to catch on fire, and the ignition characteristics of the pulverized coal are enhanced to ensure the stable combustion characteristics of the present invention. The secondary air enters the inner secondary air duct 3, the middle secondary air duct 4 and the outer secondary air duct 5 through the secondary air bellows 15 respectively. The penetration ability and the ability to entrain the primary wind are weak, and the primary wind will not be entrained prematurely. An inner cyclone 13 is arranged in the pipe 4, and an outer cyclone 14 is arranged in the outer secondary air duct 5, so that the middle and outer secondary air are rotated, and the rotation directions are the same, and they are sprayed through the middle and outer secondary air nozzles. Into the furnace, a suitable central recirculation zone is formed in the burner area to make the pulverized coal burn stably and reduce the generation of nitrogen oxides.

The working principle of the second solution of the present invention is as follows: the primary air-powder mixture enters the primary air duct 2 through the powder feeding pipe, the primary air duct 2 is provided with a pulverized coal concentrator 6, and the diameter of the concentration ring 6-2 of the pulverized coal concentrator 6 is along the diameter of the As the flow direction of the primary air pulverized coal increases in turn, the primary air pulverized coal mixture is divided into two parts after passing through the pulverized coal concentrator 6, and the area close to the inner wall of the primary air duct 2 forms a pulverized coal area, and the area close to the outer surface of the central pipe 1 forms a pulverized coal area. In the thin pulverized coal area, due to the action of the spoiler 7, the primary air pulverized coal is distributed at intervals of one thick and one thin in the circumferential direction of the outlet end of the primary air duct 2, so as to realize the staged combustion of the pulverized coal fuel in the radial and circumferential directions , increase the fuel amount in the central recirculation zone, reduce the generation of nitrogen oxides, and improve the stable combustion ability of the present invention. At the same time, a small swirl circle is formed around the spoiler 7, which is attached to the root of the high temperature recirculation zone. The secondary air enters the inner secondary air duct 3 and the outer secondary air duct 5 respectively through the secondary air bellows 15, and a spacer 16 is arranged between the primary air duct 2 and the inner secondary air duct 3, so that the present invention The primary air pulverized coal mixture and the secondary air are injected at an interval at the outlet end, which increases the distance between the primary air and the peripheral mainstream secondary air, and delays the mixing of the primary air and the secondary air. In the secondary air channel, the outer cyclone 14 is arranged in the outer secondary air channel, so that the inner and outer secondary air are rotated, and their rotation directions are the same, and are sprayed into the furnace through the inner and outer secondary air nozzles, forming a A suitable central recirculation zone enables stable combustion of pulverized coal and reduces the formation of nitrogen oxides.

Claims (10)

1. A swirl burner with a multi-stage air distribution in the radially outer rich and inner thin, characterized in that: it comprises a central pipe (1), a primary air duct (2), an inner secondary air duct (3), a middle Secondary air duct (4), outer secondary air duct (5), inner cyclone (13), outer cyclone (14), secondary air box (15), spoiler (7), pulverized coal Concentrator (6) and equalizing ring (8); The central pipe (1), the primary air duct (2), the inner secondary air duct (3), the middle and secondary air duct (4), and the outer secondary air duct (5) are assembled together from the inside to the outside in order, and are adjacent to each other. The primary air channel, the inner secondary air channel, the middle secondary air channel and the outer secondary air channel are formed in turn from the inside to the outside. The primary air duct (2), the inner secondary air duct (3), the secondary air The outlet ends of the air duct (4) and the outer secondary air duct (5) are provided with a primary air flare (9), an inner secondary air flare (10), a secondary air flare (11) and a one-to-one correspondence. The outer secondary air flare (12), the spoiler (7) is arranged on the inner wall of the outlet end of the primary air duct (2), the inner cyclone (13) is arranged in the middle and secondary air passage, the outer cyclone (14) set in the outer secondary air channel; The pulverized coal concentrator (6) comprises a support plate (6-1) and N concentration rings (6-2), where N is an integer of 2-5; The diameters of the N concentrating rings (6-2) increase in turn along the flow direction of the primary air pulverized coal, and the two adjacent concentrating rings (6-2) are arranged at a certain distance, and the N concentrating rings (6-2) The support plates (6-1) are fixed together on the outer wall of the central pipe (1), and the N concentrating rings (6-2) are adjacent to one of the outlet of the central pipe (1). side setting; The equalizing ring (8) is arranged on the inner wall of the primary air duct (2), and the equalizing ring (8) is arranged adjacent to one side of the concentrating ring (6-2) with a larger diameter. 2. The swirl burner of a kind of multi-stage air distribution according to claim 1, characterized in that: The N concentrating rings (6-2) are all conical rings, and the tapers of the N concentrating rings (6-2) are all equal. The included angle (δ) is 20° to 40°. 3. The radially outer rich and inner thin swirl burner with multi-stage air distribution according to claim 1, characterized in that: the equalizing ring (8) is arranged between the primary air flare (9) and the On the inner pipe wall of the primary air duct (2) between the pulverized coal concentrators (6), the equalizing ring (8) is adjacent to the end of the primary air flaring (9) to the end of the primary air flaring (9). The distance (Ls) of the ends is 4 to 8 times the distance (S1) from the outer wall of the central pipe (1) to the inner wall of the primary air pipe (2), and the thickness (Hs) of the equalizing ring (8) is the central pipe (2). The distance (S1) from the outer wall of (1) to the inner wall of the primary air duct (2) is 0.04 to 0.1 times. 4. The radially outer rich and inner lean swirl burner with multi-stage air distribution according to claim 1, characterized in that: the spoiler (7) is composed of a trapezoid with M plate surfaces on the same plane It is composed of plates, M is an integer of 8-16, and M trapezoidal plates are evenly arranged at the outlet end of the inner wall of the primary air duct (2), and two adjacent trapezoidal plates are arranged with a certain gap. The height of each trapezoidal plate (S ) is 0.1 to 0.4 times the distance (S1) from the outer wall of the central pipe (1) to the inner wall of the primary air duct (2). 5 . The radially outer rich and inner lean swirl burner according to claim 1 , wherein the expansion angle (β) of the primary air flare (9) is in the range of 15° ~25°, the expansion angle (γ) of the middle secondary air flare (11) is in the range of 20° to 25°, and the expansion angle (θ) of the outer secondary air flare (12) is in the range of 20° to 25° °, the expansion angle (υ) of the inner secondary air flare (10) ranges from 20° to 25°. 6 . The radially outer rich and inner lean swirl burner with multi-stage air distribution according to claim 1 , characterized in that: the end of the inner secondary air flare ( 10 ), the middle secondary air The end of the air flaring (11) is flush with the end of the primary air flaring (9). 7 . The radially outer rich and inner lean swirl burner with multi-stage air distribution according to claim 6 , wherein the length (L4) of the primary air flare (9), the inner secondary The length (L3) of the air flaring (10) and the length (L2) of the secondary air flaring (11) are equal; the length (L4) of the primary air flaring (9) is the outer secondary air flaring (12). ) is 0.4 to 0.7 times the length (L1). 8. The radially outer rich and inner thin swirl burner with multi-stage air distribution according to any one of claims 1-5, characterized in that: the length of the inner secondary air flare (10) (L3) is equal to the length (L2) of the middle and secondary air flaring (11); the length (L3) of the inner secondary air flaring (10) is the length (L1) of the outer secondary air flaring (12). ) 0.6 to 0.8 times; the length (L4) of the primary air flare (9) is 0.5 to 0.7 times the length (L3) of the inner secondary air flare (10). 9. A swirl burner with a multi-stage air distribution radially outer and inner thin, characterized in that: it comprises a central pipe (1), a primary air duct (2), an inner secondary air duct (3), an outer Secondary air duct (5), inner cyclone (13), outer cyclone (14), secondary air box (15), spoiler (7), pulverized coal concentrator (6), equalizing ring (8) and the spacer cylinder (16); The central pipe (1), the primary air duct (2), the spacer tube (16), the inner secondary air duct (3) and the outer secondary air duct (5) are assembled together in sequence from the inside to the outside. A primary air channel is formed between the primary air ducts (2), and the interval tube (16), the inner secondary air duct (3) and the outer secondary air duct (5) are adjacent to form an inner secondary air channel from the inside to the outside. and the outer secondary air channel, the two ends of the spacer cylinder (16) are respectively fixed to the primary air duct (2) through the annular plate to form a closed space, the primary air duct (2), the inner secondary air duct (3) and the outer secondary air duct (2) The outlet end of the secondary air duct (5) is provided with a primary air flaring (9), an inner secondary air flaring (10) and an outer secondary air flaring (12) in a one-to-one correspondence, and the spoiler (7) is arranged on the On the inner wall of the outlet end of the primary air duct (2), the inner cyclone (13) is arranged in the inner secondary air channel, and the outer cyclone (14) is arranged in the outer secondary air channel; The pulverized coal concentrator (6) comprises a support plate (6-1) and N concentration rings (6-2), where N is an integer of 2-5; The diameters of the N concentrating rings (6-2) increase in turn along the flow direction of the primary air pulverized coal, and the two adjacent concentrating rings (6-2) are arranged at a certain distance, and the N concentrating rings (6-2) The support plates (6-1) are fixed together on the outer wall of the central pipe (1), and the N concentrating rings (6-2) are adjacent to one of the outlet of the central pipe (1). side setting; The equalizing ring (8) is arranged on the inner wall of the primary air duct (2), and the equalizing ring (8) is arranged adjacent to one side of the concentrating ring (6-2) with a larger diameter. 10. The radially outer rich and inner thin swirl burner with multi-stage air distribution according to claim 9, characterized in that: the N concentration rings (6-2) are all conical rings, and the N concentration rings (6-2) are all conical rings. The tapers of the rings (6-2) are all equal, and the included angle (δ) between the bus bar of each concentrating ring (6-2) and the center line of the central pipe (1) is 20°˜40°.