CN216790167U

CN216790167U - Lignite boiler combustion system provided with efficient pulverized coal concentrator and low-nitrogen combustor

Info

Publication number: CN216790167U
Application number: CN202122804300.3U
Authority: CN
Inventors: 王颖; 张庆; 侯丙军
Original assignee: Transtek Industries Hk Ltd
Current assignee: Transtek Industries Hk Ltd
Priority date: 2021-11-16
Filing date: 2021-11-16
Publication date: 2022-06-21
Anticipated expiration: 2031-11-16

Abstract

The utility model discloses a lignite boiler combustion system provided with a high-efficiency pulverized coal concentrator and low-nitrogen burners, which comprises a plurality of low-nitrogen burners, wherein each low-nitrogen burner comprises a primary air pipeline, an inner secondary air pipeline, an outer secondary air pipeline and a ventilation air pipeline which are all communicated with a hearth, and an air volume adjusting valve is arranged on the ventilation air pipeline; the pulverized coal concentrators are in one-to-one correspondence with the low-nitrogen burners, the concentrated-phase pulverized coal outlet ends of the pulverized coal concentrators are detachably communicated with the corresponding primary air pipelines, and the light-phase pulverized coal outlet ends of the pulverized coal concentrators are detachably communicated with the corresponding exhaust air pipelines; and the plurality of OFA nozzles are communicated with the hearth and are axially positioned above the plurality of low-nitrogen burners along the hearth. The pulverized coal concentrator is designed, primary air can be divided, so that the proportion of the primary air and secondary air entering the combustor is reasonable, and meanwhile, the combustor can realize air staged combustion by matching with an OFA nozzle, so that the NOx emission value is reduced.

Description

Lignite boiler combustion system provided with efficient pulverized coal concentrator and low-nitrogen combustor

Technical Field

The present invention relates to the field of boiler combustion systems. More particularly, the present invention relates to a lignite boiler combustion system provided with a high efficiency pulverized coal concentrator and a low nitrogen burner.

Background

In order to meet the development requirement of atmospheric pollutant control of domestic thermal power plants, many power plants plan to carry out low-nitrogen combustion modification so as to reduce the NOx emission value at the outlet of a boiler economizer and reduce the operation cost of denitration equipment. Lignite boilers have a relatively high primary air rate from coal mills due to their high moisture content, typically greater than 35%. During practical application, if the good organization combustion of the combustor needs to be met, the proportion of primary and secondary air entering the combustor should not be higher than 1: 1.7; if the mode of air staged combustion is adopted to reduce the NOx emission value, the overfire air at the OFA nozzle is divided by about 20 percent of secondary air, so that the secondary air entering the combustor is reduced, and the combustor has the problems that the primary air and the secondary air are not in balance and the combustion cannot be well organized. Accordingly, a need exists for a combustion system that can simultaneously address both combustor tissue combustion and reduced NOx emission values.

SUMMERY OF THE UTILITY MODEL

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The utility model also aims to provide a lignite boiler combustion system provided with a high-efficiency pulverized coal concentrator and a low-nitrogen burner, which can divide primary air by designing the pulverized coal concentrator, so that the proportion of the primary air and secondary air entering the burner is reasonable, the good organization combustion of the burner is ensured, and meanwhile, the burner can realize air staged combustion by matching with an OFA nozzle, so that the NOx emission value is reduced.

To achieve these objects and other advantages and in accordance with the purpose of the utility model, there is provided a brown coal boiler combustion system provided with a high-efficiency pulverized coal concentrator and a low-nitrogen burner, comprising:

the low-nitrogen combustors comprise a secondary air pipeline and a ventilation air pipeline arranged above the secondary air pipeline; the primary air pipeline, the inner secondary air pipeline, the outer secondary air pipeline and the ventilation air pipeline are all communicated with a hearth, an air quantity adjusting valve is arranged on the ventilation air pipeline, and swirl strength adjusting valves are arranged on the inner secondary air pipeline and the outer secondary air pipeline;

the pulverized coal concentrators are in one-to-one correspondence with the low-nitrogen burners, the concentrated-phase pulverized coal outlet ends of the pulverized coal concentrators are detachably communicated with the corresponding primary air pipelines, and the light-phase pulverized coal outlet ends of the pulverized coal concentrators are detachably communicated with the corresponding exhaust air pipelines;

and the plurality of OFA nozzles are communicated with the hearth and are axially positioned above the plurality of low-nitrogen burners along the hearth.

Preferably, each OFA nozzle comprises a central direct-flow pipeline and an outer ring rotational-flow pipeline which are sequentially sleeved from inside to outside, and a rotational-flow strength adjusting valve is arranged on the outer ring rotational-flow pipeline.

Preferably, an air volume adjusting valve is arranged on the inner secondary air pipeline.

Preferably, through flange joint between two arbitrary pipelines, and the junction presss from both sides and is equipped with the leak detection subassembly, the leak detection subassembly is established including dismantling the sealed cover on the flange, establishing detection piece on the sealed cover, detection piece is including establishing pipe on the sealed cover inner wall, establishing in the pipe and with switch, the establishment of sealed cover inner wall rigid coupling are in sealed cover and with the alarm of switch electricity connection, run through on the sealed cover that the pipe covered be equipped with the through-hole of pipe and external intercommunication, keep away from in the pipe the one end sliding seal of switch is equipped with the movable plate, the movable plate orientation the one side of switch is equipped with the trigger bar, and when flange department had gas leakage, the gaseous movable plate that promotes of leakage, and then drives the trigger bar extrusion the switch triggers the warning.

Preferably, the alarm is an alarm lamp.

Preferably, the sealing cover comprises a pipe fitting and a plurality of clamping hoops sleeved on the pipe fitting; the pipe fitting comprises a pair of semicircular clamping plates which are oppositely arranged, the diameters of the two ends of each clamping plate are matched with the corresponding pipeline, the diameter of the middle part of each clamping plate is larger than the outer diameter of the corresponding flange, first sealing layers are laid on the inner walls of the two ends of each clamping plate, a second sealing layer is laid on the edge, facing the other clamping plate, of one clamping plate, the two ends of each clamping plate are clamped on the pipelines on the two sides of the flange, the middle part of each clamping plate covers the corresponding flange, and therefore a sealing cover for covering the flange is formed.

Preferably, the trigger lever is in the shape of a convex semicircle facing the end of the switch.

Preferably, the number of the clamping bands is three, and the three clamping bands are respectively arranged at the two ends and the middle part of the pair of clamping plates.

The utility model at least comprises the following beneficial effects:

the utility model provides a combustion system capable of simultaneously considering the organization combustion of a cyclone burner and reducing the NOx emission value, wherein a primary air pipeline, an inner secondary air pipeline, an outer secondary air pipeline, an exhaust air pipeline, an air volume regulating valve, a coal powder concentrator and OFA nozzles are designed, the dense-phase coal powder outlet end of the coal powder concentrator is communicated with the primary air pipeline, and the light-phase coal powder outlet end of the coal powder concentrator is communicated with the exhaust air pipeline, so that the air rate of primary air entering the burner can be reduced, the proportion of the primary air and the secondary air entering the burner can be positioned in a reasonable range by regulating the air volume regulating valve on the exhaust air pipeline, the good organization combustion of the burner is ensured, meanwhile, the burner and the OFA nozzles are matched to realize air staged combustion, the NOx emission value is reduced, the ammonia injection amount is reduced, and the operation cost is reduced; the total reaction amount of the denitration catalyst is reduced, the service life of the catalyst is prolonged, the operation cost of denitration is integrally reduced, and the win-win environment and economic benefits are realized.

Additional advantages, objects, and features of the utility model will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the utility model.

Drawings

Fig. 1 is a schematic structural diagram of a lignite boiler combustion system provided with a high-efficiency pulverized coal concentrator and a low-nitrogen burner, which is arranged on a hearth according to one technical scheme of the utility model;

FIG. 2 is a schematic structural diagram of a low-nitrogen burner according to one embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an OFA nozzle according to one embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a leak detection mechanism according to one embodiment of the present invention installed on a pipeline;

FIG. 5 is an enlarged view taken at A in FIG. 4;

FIG. 6 is a side view of a leak detection mechanism according to one embodiment of the present invention;

FIG. 7 is a top view of a leak detection mechanism according to one embodiment of the present invention;

fig. 8 is a front view of a leak detection mechanism according to one embodiment of the present invention.

Reference numerals: 1-a low nitrogen burner; 101-a pulverized coal concentrator; 102-primary air duct; 103-a ventilation air duct; 104-inner secondary air duct; 105-an outer secondary air duct; 106-inner secondary axially adjustable vanes; 107-outer secondary axially adjustable vanes; 2-OFA nozzle; 201-central straight flow pipe; 202-outer ring swirl pipe; 203-outer ring rotational flow axial adjustable blades; 3-hearth; 4-clamping plate; 5-a flange; 6-a sealing gasket; 8, clamping a hoop; 9-an alarm lamp; 10-a first sealing layer; 11-round tube; 12-a switch; 13-moving the plate; 14-a trigger lever; 15-a through hole; 16-second sealing layer.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the utility model by referring to the description text.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

As shown in fig. 1 to 8, the present invention provides a lignite boiler combustion system provided with a high efficiency pulverized coal concentrator and a low nitrogen burner, comprising:

the low-nitrogen burners 1 comprise a secondary air pipeline and a ventilation air pipeline 103 arranged above the secondary air pipeline; the primary air pipeline 102, the inner secondary air pipeline 104, the outer secondary air pipeline 105 and the ventilation air pipeline 103 are all communicated with the hearth 3, an air volume adjusting valve is arranged on the ventilation air pipeline 103, and swirl strength adjusting valves are arranged on the inner secondary air pipeline 104 and the outer secondary air pipeline 105;

the pulverized coal concentrator 101 is in one-to-one correspondence with the low-nitrogen burners 1, the concentrated-phase pulverized coal outlet end of the pulverized coal concentrator 101 is detachably communicated with the corresponding primary air pipeline 102, and the light-phase pulverized coal outlet end of the pulverized coal concentrator 101 is detachably communicated with the corresponding ventilation air pipeline 103;

the OFA nozzles 2 are communicated with the hearth 3, and the OFA nozzles 2 are axially positioned above the low-nitrogen burners 1 along the hearth 3;

in the above technical solution, a space between the outer wall of the primary air duct 102 and the inner wall of the inner secondary air duct 104 forms a channel for inner secondary air, a space between the outer wall of the inner secondary air duct 104 and the inner wall of the outer secondary air duct 105 forms a channel for outer secondary air, the inner secondary air duct 104, the outer secondary air duct 105 and the OFA nozzle 2 are all communicated with a secondary air box, so that a secondary air source is provided for the three ducts, and the inner secondary air and the outer secondary air entering the burner are secondary air at the burner, the inner secondary air duct 104 is provided with a swirl strength adjusting valve in which inner secondary air axially adjustable blades 106 form adjustable swirl strength, and the outer secondary air duct 105 is provided with an outer secondary air axially adjustable blade 107 forming an adjustable swirl strength adjusting valve in which swirl strength is adjustable, so as to adjust the swirl strength of the inner secondary air and the outer secondary air; the pulverized coal concentrator 101 is a device well known by a person skilled in the art, in the technical scheme, the pulverized coal concentrator 101 is a centrifugal pulverized coal concentrator 101, the pulverized coal concentrator 101 is provided with a concentrated-phase pulverized coal outlet end and a light-phase pulverized coal outlet end, the powder inlet end of the pulverized coal concentrator 101 is communicated with a primary air pulverized coal pipeline of a coal mill, primary air pulverized coal airflow from the coal mill is divided into concentrated-phase pulverized coal (the content of the pulverized coal is 88% -93%) and light-phase pulverized coal (the content of the pulverized coal is 7% -12%) after passing through the pulverized coal concentrator 101, the concentrated-phase pulverized coal flows to the primary air pipeline 102 of the low-nitrogen combustor 1 to form primary air of the combustor, the primary air is sprayed into a hearth 3 to be combusted, and the light-phase pulverized coal flows to a ventilation air pipeline 103 of the low-nitrogen combustor 1 to form ventilation air of the combustor, and then the ventilation air of the combustor is sprayed into the hearth 3 to be combusted; the air volume of the primary air entering the burner can be adjusted by adjusting an air volume adjusting valve (not shown in figure 2) on the ventilation air duct 103, so that the air rate of the primary air can be adjusted, the proportion of the primary air and the secondary air entering the burner is always kept in a reasonable range, the safe, stable, efficient and good combustion of the burner can be ensured, meanwhile, as the primary air rate at the burner is reduced, the air volume participating in the early combustion of the pulverized coal is reduced, the ventilation air is sprayed into the hearth 3 from the ventilation air duct 103, the air classification is further strengthened, and the purpose of reducing NOx is achieved; the OFA nozzle 2 and the low-nitrogen combustor 1 are provided, and the oxygen concentration in the main combustion region is reduced by utilizing the principle of the large-scale combustion of the combustion air in the space, and the air amount in the main combustion region is controlled to be less than the theoretical air amount. On the other hand, because the main combustion area is in the reducing atmosphere below the theoretical air quantity, the generation of fuel type NOx is greatly reduced, and meanwhile, the reducing substance generated by the oxygen-deficient combustion is beneficial to reducing the generated NOx into N2, so that the NOx emission value is reduced on the whole;

in the technical scheme, in the using process, primary air and pulverized coal from a coal mill are processed by the pulverized coal concentrator 101 to form primary air introduced into the combustor primary air pipeline 102 and ventilation air introduced into the combustor ventilation air pipeline 103, so that the primary air rate introduced into the combustor primary air pipeline 102 is reduced; the secondary air from the secondary air box is divided into two parts, one part is in a combustor inner secondary air pipeline 104 and an outer secondary air pipeline 105 in the same direction, the other part is in an OFA nozzle 2 in the same direction, a small amount of inner secondary air is used for igniting the pulverized coal, a large amount of outer secondary air is used for supplementing air required by burnt pulverized coal to be burnt out and enabling the burnt pulverized coal to be completely burnt, rotary air flow can be formed by arranging axial adjustable blades, the rotary air flow can suck high-temperature flue gas in a hearth 3 into a pulverized coal ignition area to enable the pulverized coal to be ignited and stably burnt, and a grading air supply dividing mode is adopted, so that ignition and stable burning of the pulverized coal are facilitated, and generation of NOx in flame is also facilitated to be controlled;

by adopting the technical scheme, the combustion system capable of simultaneously combining the tissue combustion of the cyclone burner and reducing the NOx emission value is provided, through designing the primary air pipeline 102, the inner secondary air pipeline 104, the outer secondary air pipeline 105, the ventilation air pipeline 103, the air volume adjusting valve, the coal powder concentrator 101 and the OFA nozzle 2, the dense-phase coal powder outlet end of the coal powder concentrator 101 is communicated with the primary air pipeline 102, the weak-phase coal powder outlet end of the coal powder concentrator is communicated with the ventilation air pipeline 103, the air rate of primary air entering the burner can be reduced, the proportion of the primary air and the secondary air entering the burner can be positioned in a reasonable range by adjusting the air volume adjusting valve on the ventilation air pipeline 103, the good tissue combustion of the burner is ensured, meanwhile, the air staged combustion is realized by matching the burner with the OFA nozzle 2, and the NOx emission value is reduced.

In another technical scheme, each OFA nozzle 2 comprises a central direct current pipeline 201 and an outer ring rotational flow pipeline 202 which are sequentially sleeved from inside to outside, and an outer ring rotational flow strength adjusting valve is arranged on the outer ring rotational flow pipeline 202; specifically, the overfire air fed into the OFA is over-fire air; as shown in fig. 1, the depth direction of the hearth 3 is the left-right direction in the figure; the utility model discloses a burner, including outer loop whirl pipeline 202, central direct current pipeline 201, outer loop whirl pipeline 3, outer loop whirl pipeline 202 is equipped with outer loop whirl axial adjustable blade 203, be equipped with outer loop whirl axial adjustable blade 203 in the outer loop whirl pipeline 202 and form whirl intensity adjusting valve for adjust outer loop whirl pipeline 202's whirl intensity, after the overgrate air gets into OFA spout 2, central direct current pipeline 201 is the direct current wind in order to keep the rigidity of air inlet, and then in order to guarantee to have sufficient penetrating power along 3 depth directions of furnace, send out the burn-up wind to furnace 3 centers, outer loop whirl pipeline 202 is equipped with outer loop whirl axial adjustable blade 203, the rotatory air current that produces helps air and flue gas fully to mix in furnace 3 width direction and near wall department, consequently, can guarantee to carry out the intensive mixing with the after-burn wind from furnace 3 degree of depth and width direction, the necessary oxygen content is provided for the later stage burning of buggy, and guarantee the abundant burn-off of buggy granule and the reductive substance complete combustion that will produce earlier stage.

In another technical scheme, an air volume adjusting valve is arranged on the inner secondary air pipeline 104 and is used for adjusting the proportion of the air volume of the inner secondary air and the air volume of the outer secondary air.

In another technical scheme, connect through flange 5 between two arbitrary pipelines, and the junction presss from both sides and is equipped with the leak detection subassembly, the leak detection subassembly is established including dismantling sealed cover on the flange 5, establishing the detection piece on the sealed cover, the detection piece is including establishing pipe 11 on the sealed cover inner wall, establishing in the pipe 11 and with switch 12 of sealed cover inner wall rigid coupling, establish on the sealed cover and with the alarm that switch 12 electricity is connected, run through on the sealed cover that pipe 11 covers with through-hole 15 of pipe 11 and external intercommunication, keep away from in the pipe 11 one end sliding seal of switch 12 is equipped with movable plate 13, movable plate 13 orientation the one side of switch 12 is equipped with trigger bar 14, and when flange 5 department had the movable plate to leak, the gas that leaks promoted 13, and then drives trigger bar 14 extrusion switch 12, triggering an alarm;

in the technical scheme, a primary air pipeline is connected with a pipeline at a concentrated-phase coal powder outlet end of a coal powder concentrator through a flange 5, an exhaust air pipeline is connected with a pipeline at a light-phase coal powder outlet end of the coal powder concentrator through a flange 5, a powder inlet end of the coal powder concentrator is connected with a primary air powder airflow pipeline of a coal mill through a flange 5, and when the primary air pipeline and the light-phase coal powder outlet end of the coal powder concentrator are connected, the two flanges 5 are hermetically connected through a sealing gasket 6; the switch 12 is an extrusion type switch 12, and when external force extrudes the switch 12 to be communicated with a circuit, alarm can be triggered; the alarm can be a light alarm or a sound alarm;

in the technical scheme, when the gas leakage alarm is used, when gas leaks from the joint of the flange 5 of the pipeline, the joint of the flange 5 is positioned in a sealed cover, so that the leaked gas can push the movable plate 13 to move, further push the trigger rod 14 to be in contact with the switch 12 and press the switch 12 to enable the alarm to alarm, and workers can find the leakage position in time conveniently;

by adopting the technical scheme, the beneficial effect is that whether gas leakage exists at the joint of the pipeline flange 5 can be detected in time by designing the sealing cover, the circular tube 11, the alarm, the through hole 15, the moving plate 13 and the trigger rod 14.

In another technical scheme, the alarm is an alarm lamp 9; by adopting the technical scheme, the alarm lamp 9 has the advantages of being striking, easy to obtain and good in alarm effect.

In another technical scheme, the sealing cover comprises a pipe fitting and a plurality of clamping hoops 8 sleeved on the pipe fitting; the pipe fitting comprises a pair of semicircular clamping plates 4 which are oppositely arranged, the diameters of the two ends of each clamping plate 4 are matched with the diameters of corresponding pipelines, the diameter of the middle part of each clamping plate 4 is larger than the outer diameter of the corresponding flange 5, first sealing layers 10 are laid on the inner walls of the two ends of each clamping plate 4, a second sealing layer 16 is laid on the edge, facing the other clamping plate 4, of one clamping plate 4, the two ends of each clamping plate 4 are clamped on the pipelines on the two sides of the flange 5, and the middle part of each clamping plate 4 covers the corresponding flange 5 so as to form a sealing cover for covering the flange 5; in the technical scheme, the vertical section of each clamping plate 4 is semicircular, the inner walls of the two ends of each clamping plate 4 are provided with first sealing layers 10, the clamping plates 4 are buckled to form a pipe fitting, the two ends of the pipe fitting are clamped on pipelines on the two sides of the flange 5, and the diameter of the middle part of the pipe fitting is larger than the outer diameter of the flange 5, so that a space for detecting whether gas leaks is formed; the first sealing layer 10 and the second sealing layer 16 are both made of rubber; adopt this technical scheme, the beneficial effect who obtains is through designing a pair of splint 4, a plurality of clamp 8, first sealing layer 10, second sealing layer 16, provides the structure of the sealed effectual sealed cowling, and the design of first sealing layer 10, second sealing layer 16 can make the both ends of pipe fitting press from both sides the pipeline seal of flange 5 both sides tightly on the one hand, and on the other hand can make and form a inclosed space between whole flange 5 and the pipe fitting inner wall, conveniently detects whether there is gas leakage.

In another technical scheme, the end part of the trigger rod 14 facing the switch 12 is in a convex semicircular shape, and by adopting the technical scheme, the beneficial effects that the damage caused by abrasion between the trigger rod 14 and the switch 12 can be reduced and the service lives of the switch 12 and the trigger rod 14 are prolonged by designing the end part of the trigger rod 14 facing the switch 12 into the convex semicircular shape are obtained.

In another technical scheme, the number of the clamp hoops 8 is three, and the three clamp hoops 8 are respectively arranged at the two ends and the middle part of the pair of clamping plates 4; by adopting the technical scheme, the obtained beneficial effects are that the three hoops 8 are distributed at the two ends and the middle part of the pair of clamping plates 4, the sealing effect between the pair of clamping plates 4 can be improved, and the sealing effect at the covering position of the flange 5 is improved.

The utility model has the following applications:

the burners of a certain 600MW boiler are symmetrically arranged on the front wall and the rear wall and are combusted in a hedging mode. The front wall is provided with 4 layers of burners, the rear wall is provided with 3 layers of burners, and each layer is provided with 6 burners and 42 burners in total. The coal for boiler combustion is white-tone coal mine old brown coal, the boiler operation primary air rate is about 37% before modification, no over-fire air nozzle is arranged, all secondary air enters the hearth from the burner nozzle, the secondary air volume and the primary air volume ratio of the burner can meet the design requirements of the cyclone burner, but the NOx emission value is higher, in order to achieve the purpose of reducing the NOx emission value, air classification is needed in the height direction of the hearth, a part of secondary air is sent into the hearth from the over-fire air nozzle, the secondary air volume of the lower hearth is reduced at the moment, and the ratio of the secondary air volume and the primary air volume of the burner nozzle is disordered; therefore, the primary air from the coal mill needs to be separated, and the ratio of the primary air to be sent into a hearth from a burner nozzle is reduced, so that the primary air and secondary air proportioning requirements of the cyclone burner are met.

By arranging the pulverized coal concentrator and replacing the original burner with a low-nitrogen burner, the primary air pulverized coal airflow from the coal mill passes through the pulverized coal concentrator, most pulverized coal flows along the inner wall of the outer side of the elbow under the action of centrifugal force, so that 50% of primary air and 7% -12% of pulverized coal are separated, are guided to the exhaust nozzle through the exhaust pipe and are directly sprayed into the hearth for combustion, and the rest 50% of primary air and 88% -93% of pulverized coal are sprayed into the furnace for combustion through the primary air nozzle of the burner.

After primary air is concentrated, conditions are created for staged combustion of air in the height direction of a hearth, double-air-zone over-fire air nozzles are added about 7 m above a combustor, and 6 air-over-fire air nozzles are added on each of front and rear walls and correspond to the combustor one by one; and 2 overfire air nozzles in double air areas are respectively added near the central lines of the two side walls of the hearth, and 16 overfire air nozzles are added in total. And the air is supplied in a grading way to a greater extent, the grading combustion of the pulverized coal is further realized, and the emission of NOx is reduced to the greatest extent.

The number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the lignite boiler combustion system of the present invention provided with the high efficiency pulverized coal concentrator and the low nitrogen burner will be apparent to those skilled in the art.

While embodiments of the utility model have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the utility model pertains, and further modifications may readily be made by those skilled in the art, it being understood that the utility model is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims

1. Lignite boiler combustion system provided with high-efficiency pulverized coal concentrator and low-nitrogen combustor, and is characterized by comprising:

the low-nitrogen burners comprise a secondary air pipeline and an exhaust air pipeline arranged above the secondary air pipeline; the primary air pipeline, the inner secondary air pipeline, the outer secondary air pipeline and the ventilation air pipeline are all communicated with a hearth, an air quantity adjusting valve is arranged on the ventilation air pipeline, and swirl strength adjusting valves are arranged on the inner secondary air pipeline and the outer secondary air pipeline;

2. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen combustor as claimed in claim 1, wherein each OFA nozzle comprises a central straight-flow pipeline and an outer ring swirling pipeline which are sequentially sleeved from inside to outside, and a swirling intensity adjusting valve is arranged on the outer ring swirling pipeline.

3. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen burner as claimed in claim 1, wherein an air volume adjusting valve is arranged on the inner secondary air pipeline.

4. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen combustor according to claim 1, wherein any two pipelines are connected through a flange, a leakage detection assembly is clamped at a joint and comprises a sealing cover which is detachably sleeved on the flange, and a detection piece which is arranged on the sealing cover, the detection piece comprises a round pipe which is arranged on the inner wall of the sealing cover, a switch which is arranged in the round pipe and fixedly connected with the inner wall of the sealing cover, and an alarm which is arranged on the sealing cover and electrically connected with the switch, a through hole which is used for communicating the round pipe with the outside is arranged on the sealing cover covered by the round pipe in a penetrating manner, one end of the round pipe, which is far away from the switch, is provided with a trigger rod in a sliding sealing manner, one surface of the moving plate, which faces the switch, is provided with a trigger rod, and when gas leaks from the flange, the leaked gas pushes the movable plate, so that the trigger rod is driven to extrude the switch, and the alarm is triggered.

5. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen burner as claimed in claim 4, wherein the alarm is an alarm lamp.

6. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen combustor according to claim 4, wherein the sealing cover comprises a pipe fitting and a plurality of clamping hoops sleeved on the pipe fitting; the pipe fitting comprises a pair of semicircular clamping plates which are oppositely arranged, the diameters of the two ends of each clamping plate are matched with the corresponding pipeline, the diameter of the middle part of each clamping plate is larger than the outer diameter of the corresponding flange, first sealing layers are laid on the inner walls of the two ends of each clamping plate, a second sealing layer is laid on the edge, facing the other clamping plate, of one clamping plate, the two ends of each clamping plate are clamped on the pipelines on the two sides of the flange, the middle part of each clamping plate covers the corresponding flange, and therefore a sealing cover for covering the flange is formed.

7. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen burner as claimed in claim 4, wherein the trigger bar is in a convex semicircular shape toward an end of the switch.

8. The lignite boiler combustion system provided with the high-efficiency pulverized coal concentrator and the low-nitrogen burner as claimed in claim 6, wherein the number of the clips is three, and the three clips are respectively arranged at both ends and the middle part of the pair of clamping plates.