WO2012163107A1

WO2012163107A1 - Dense-phase swirl pulverized coal burner

Info

Publication number: WO2012163107A1
Application number: PCT/CN2012/071214
Authority: WO
Inventors: 李月华
Original assignee: 上海锅炉厂有限公司
Priority date: 2011-05-27
Filing date: 2012-02-16
Publication date: 2012-12-06
Also published as: CN102393015A; PL403824A1

Abstract

A dense-phase swirl pulverized coal burner comprises a primary wind channel (2), a straight-flow secondary wind channel (2), and a swirl-flow secondary wind channel (3) at the outermost side. The primary wind channel (1) comprises an elbow section serving as an inlet of pulverized coal and a straight pipe section arranged horizontally. An oil gun sleeve (4) is arranged at a central axis in the straight pipe section, and several stages of pulverized coal concentration rings (6) are arranged at intervals in an axial direction of the oil gun sleeve (4), so that the pulverized coal forms gas flow distribution with higher outer density and lower inner density at a primary wind nozzle. The pulverized coal burner has characteristics such as stable flame, strong ignitability, strong adaptability to coal types, and low emission of nitrogen oxides. Moreover, the primary wind channel has a simple structure and low resistance, and can effectively retard the rate of wear of members.

Description

Dense phase swirling pulverized coal burner

Technical field

The invention relates to the technical field of a coal-fired boiler of a power station, in particular to a dense phase swirling pulverized coal burner used in a coal-fired boiler. Background technique

In recent years, with the increasingly strict control of nitrogen oxide emissions from coal-fired power station boilers, a full-furnace staged combustion low-NOx technology with low NOx burner technology has been widely used, among which various types have been formed in wall-type boilers. Genre low NOx swirl burner technology.

In the wall boiler, in order to effectively reduce the nitrogen oxides produced by combustion in the furnace, the whole furnace grading combustion technology adopts the early technology to meet the burnout from the main combustion area (ie, the pulverized coal is fed into the furnace area of the furnace, It is called the main combustion zone. A part of the oxygen supplied is delayed from the special tuyere on the upper part of the furnace to the furnace, so that the air chemical equivalent ratio of the main combustion zone is less than 1, that is, an oxygen-deficient combustion atmosphere is formed, and the main combustion zone and the upper tuyere are simultaneously formed. A region of reducing atmosphere is formed between the (burnout zone) to allow sufficient reduction of early nitrogen oxides. At the same time, most of the swirl burners used are in the form of rich and light combustion and multi-channel grading air supply, which controls the mixing timing of the wind powder, forms a reducing atmosphere in the burner area, and achieves the purpose of reducing nitrogen oxides in the burner area.

However, through the application of the above burner technology, there are currently three problems: 1. In order to make the pulverized coal gas flow in the primary air passage uniform and effectively separate into two shades, the structure is often relatively complicated, not only increased The system resistance increases the fan load and the power consumption of the plant. At the same time, it is easy to cause wear in the channel, shortening the service life of the equipment and increasing the operation and maintenance cost of the power plant. 2. The adaptability of the coal type is poor, especially with the power of China. The coal quality deteriorates, and the actual coal combustion type does not meet the original design requirements. The burner exit flame often appears unstable when the boiler is peak-adjusting; 3. The primary air pulverized coal gas flow and the burner nozzle secondary air The late mixing performance of the flow is poor, and the unburned loss of the boiler is increased. Summary of the invention

The object of the present invention is to provide a dense phase pulverized coal pulverized coal burner applied to a coal-fired boiler of a power station, which convects a dense phase pulverized coal powder through a spout to strengthen the mixing of the dense phase pulverized coal gas stream and the high temperature recirculation zone of the outlet. To the rapid ignition and stable combustion of pulverized coal; at the same time, it can control the timely mixing of secondary air and primary air, strengthen the late mixing and full combustion of pulverized coal gas flow; and the structure of pulverized coal concentration ring inside primary air passage is simple and the resistance is small. Effectively delays wear and extends equipment maintenance intervals.

In order to achieve the above object, the technical solution of the present invention provides a dense phase swirling pulverized coal burner comprising:

a primary air passage provided with the following components in sequence: an elbow section as a pulverized coal inlet, a horizontally disposed straight pipe section, and a primary air vent; a oil gun casing disposed on a central shaft in the straight pipe section , the oil gun casing is provided with a burner ignition oil gun;

The method further includes: a DC secondary air passage disposed around the outer wall of the nozzle of the primary air passage; and a swirling secondary air passage disposed around the outer wall of the nozzle of the direct current secondary air passage; the DC secondary air The channel and the swirling secondary air passage are matched in the same large wind box. An adjusting device for adjusting the air volume is disposed in the DC secondary air passage; and an adjusting device for adjusting the swirling wind strength is disposed in the swirling secondary air passage.

Wherein, the pulverized coal averaging plate is disposed in the elbow section of the primary air passage, and is arranged along the central axis of the elbow section, and is divided into two layers of airflow passages in the elbow section; One end of the plate is located at the inlet of the elbow section, and the other end extends to the outlet of the elbow section, that is, a position where the elbow section communicates with the straight pipe section, so that the pulverized coal gas flows through the elbow section and is evenly distributed in the circumferential direction. Enter the straight pipe section.

In the straight pipe section of the primary air passage, a plurality of stages of pulverized coal concentrating rings are arranged along the axial interval of the oil gun casing; each of the pulverized coal concentrating rings is disposed around the outer edge of the oil gun casing The expanding cone structure has an opening of the expanding cone facing the nozzle of the primary air, and after several stages of expanding the cone, the pulverized coal gas flow forms an outer concentrated light pulverized coal gas flow distribution at the nozzle of the primary air.

Preferably, the oil gun casing of the straight pipe section is spaced apart from the pulverized coal concentrating ring of 2~3 grades, and the size of the pulverized coal concentrating ring of each stage is enlarged step by step. The pulverized coal concentration ring of each stage has a taper angle of 10 ° ~ 25 . In the range.

a plurality of guiding blades are evenly arranged around the inner wall of the first air passage; the guiding positions of the guiding blades are matched with the path area of the dense phase pulverized coal gas flow around the nozzle, only the outer periphery The dense phase pulverized coal is disturbed, and the dense phase pulverized coal gas stream is formed into a certain swirling direction; and the light phase pulverized coal gas stream in the center of the nozzle is directly sprayed into the external furnace.

Preferably, the nozzle of the primary air passage is provided with 10 to 20 pieces of the guide vanes around the inner wall thereof. The angle between each guide vane and the axial direction of the primary air passage is 10° ~ 30°, and the guide vanes The radial height along the primary air passage is 0.05 to 0.1 times the diameter of the primary air passage.

The primary air passage, the direct current secondary air passage, and the outer wall of the spout secondary air passage are respectively provided with a expanding cone structure; the plurality of expanding cone structures are respectively provided with a taper opening toward the outer furnace. To delay the mixing time of the secondary air and the primary wind.

Preferably, the plurality of expanding cone structures have a taper angle of less than or equal to 45 °.

Compared with the prior art, the dense phase swirling pulverized coal burner of the present invention has the advantages that: in the present invention, when the primary air enters, the pulverized coal flow equalizing plate is formed, and relatively uniform two layers are formed in the circumferential direction of the air passage; After that, due to the action of several stages of pulverized coal concentrating rings in the horizontal straight pipe section, the primary air is formed into a thick and inner light distribution form at the spout by the taper action.

Since the expanding cone structure is respectively arranged on the nozzles of the primary air and the secondary air, the secondary air is delayed by the expansion cone and the mixing time with the primary air; by the reasonable control of the expansion cone angle, once in the initial stage of the fire An oxygen-deficient atmosphere is formed inside the wind to sufficiently reduce the initial nitrogen oxides. First, the timely mixing of the secondary air can keep the nozzle water wall in the oxidizing atmosphere for a long time, effectively preventing the slagging and high temperature corrosion of the water wall in the burner area.

At the same time, due to the expansion of the primary air nozzle, a high-temperature flue gas recirculation zone is formed on the outer periphery of the nozzle; by arranging a plurality of guide vanes on the inner wall of the primary air passage, the dense phase coal powder is disturbed before being injected into the furnace, and a certain rotation is formed. The high-temperature flue gas recirculation zone is sprayed into the high-temperature flue gas recirculation zone to perform intense mixed combustion for the purpose of fast ignition and enhanced combustion.

In addition, the light-phase pulverized coal in the center of the primary air nozzle is injected into the furnace with direct current, and the rigidity of the primary air is maintained, so that the primary air can be fully mixed and burned in the later stage.

Therefore, the present invention has a strong adaptability to variable coal types. According to the different coal types, the design of the taper angle and the number of stages of the pulverized coal concentration ring can control the degree of separation of the pulverized coal; by the radial height of the guide vanes and the design of the angle between the guide vanes and the axial direction, The size of the spoiler of the dense phase coal powder is controlled; the size of the high temperature recirculation zone can be controlled by the expansion cone structure of the primary air nozzle. According to the change of coal quality during operation, the swirling intensity of the secondary air can be adjusted by the adjusting device to meet the requirements of different coal quality ignition and stable combustion.

The primary air passage of the invention has simple structure and excellent anti-wear performance; the overall ignition is stable and stable, and the coal quality is good; and the utility model has the characteristics of high efficiency and low nitrogen oxide emission. DRAWINGS BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view showing the overall structure of a dense phase swirling pulverized coal burner according to the present invention; and Figure 2 is a schematic view showing the arrangement of guide vanes of the burner nozzle of the present invention. Concrete real

Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the dense phase swirling pulverized coal burner (hereinafter referred to as a burner) of the present invention comprises a primary air passage 1, a DC secondary air passage 2 disposed around the outer wall of the nozzle of the primary air passage 1, and surrounding The swirling secondary air passage 3 is disposed on the outer wall of the nozzle of the direct current secondary air passage 2. The DC secondary air passage 2 and the swirling secondary air passage 3 are distributed in the same large wind box.

Wherein, the primary air passage 1 is provided with the following components that are sequentially connected: an elbow section as a pulverized coal inlet, a straight pipe section arranged horizontally, and a vent of a primary air. On the central shaft in the straight pipe section of the primary air passage 1, a oil gun casing 4 is disposed; the oil gun casing 4 is provided with a burner ignition oil gun.

In the elbow section of the primary air passage 1, a pulverized coal averaging plate 5 is disposed, which is arranged along the central axis of the elbow section, and divides the elbow section into two inner and outer rafts which are close to and away from the center of the turn. a layer air flow passage; the pulverized coal averaging plate 5 end is located at the inlet of the elbow section, and the other end extends to the outlet of the elbow section, that is, a position where the elbow section communicates with the straight pipe section. Therefore, when the primary pulverized coal gas flow enters through the elbow section of the primary air passage 1, and the pulverized coal equalizing plate 5 re-enters the horizontal straight pipe section, a uniform and uniform flow of air is formed. It ensures that the pulverized coal is relatively uniform in the circumferential direction at the exit of the elbow section.

Further, in the horizontal straight pipe section of the primary air passage 1, a pulverized coal concentrating ring 6 of 2~3 stages is arranged axially along the oil gun casing 4; each pulverized coal concentrating ring 6 It is a taper structure disposed around the outer edge of the oil gun casing 4, and the opening of the taper is directed toward the spout, and the taper angle α is 10°-25. Within the scope; the size of the pulverized coal concentrating ring 6 of each stage is enlarged step by step. After the pulverized coal averaging plate 5 acts, the pulverized coal gas stream uniformly distributed when entering the straight pipe section passes through the expanded cone structure of the pulverized coal concentrating ring 6 of each stage, and most of the pulverized coal gas flow is due to inertia. Will remain in the straight section of the primary air passage 1 away from the periphery of the central axis; and the air flow entraining part of the fine coal powder flows in the straight pipe section closer to the center of the central axis due to inertia, and finally in the primary wind At the spout of the passage 1, a condensed pulverized coal gas flow distribution form is formed.

Referring to FIG. 1 and FIG. 2, at the nozzle of the primary air passage 1, a plurality of guide vanes 7 are uniformly arranged around the inner wall thereof, and the number of blades is 10-20 pieces; each guide vane 7 and the guide vane 7 The axial angle of the primary air passage 1 is 10° to 30°, and the radial height along the primary air passage 1 is 0.05 to 0.1 times the diameter of the primary air passage 1. That is to say, the plurality of guide vanes 7 are arranged in the flow passage region of the dense phase pulverized coal in the outer periphery of the passage, and the disturbance of the dense phase airflow is increased before the injection into the furnace to form a certain swirling discharge; The light phase pulverized coal gas stream is still DC and is injected into the furnace along the axis of the channel.

The primary air passage 1, the direct current secondary air passage 2, the swirling secondary air passage 3, and the outer wall of the nozzle facing one end of the furnace are respectively provided with a diffusing cone structure, which corresponds to the serial numbers 8, 9, 10 in FIG. It is indicated that the secondary air is delayed by the expansion of the primary air by the expansion cone. By controlling a reasonable taper angle, an oxygen-deficient atmosphere can be formed inside the primary air at the beginning of the fire, and the initial nitrogen oxides can be sufficiently reduced. Corresponding to the expanding cone structure 8, 9, 10, each of the preferred cone angles β1, β2, β3 is less than or equal to 45 °.

Further, since the arrangement of the expanding cone structure 8 forms a negative pressure inside, a high-temperature flue gas is taken up at the nozzle of the primary air passage 1, and an annular high-temperature flue gas recirculation zone is formed. In this way, the dense phase pulverized coal gas stream located on the outer periphery of the primary air nozzle directly enters the high temperature flue gas recirculation zone after being disturbed by the guide vanes 7, and the strong mixing causes the pulverized coal gas stream to instantaneously obtain a large heat rise and burns. .

At the same time, according to the arrangement of the expanding cone structures 8 and 9, the adjusting devices 11 and 12 for adjusting the air volume and the swirling wind intensity are respectively arranged in the direct current secondary air passage 2 and the swirling secondary air passage 3 to control two The timing of the secondary wind mixing into the wind. First, the timely mixing of the secondary air can make the nozzle water wall long-term in the oxidizing atmosphere, effectively preventing the slagging and high temperature corrosion of the water wall of the burner area.

Moreover, the light-phase pulverized coal gas flow located at the center of the primary air vent is directly injected into the furnace along the axial direction of the air duct due to the absence of turbulence, maintaining the rigidity of the primary air and being able to be injected into the furnace to a certain depth. The swirling secondary air is strongly mixed under the turbulence of the secondary air to ensure the late mixing and combustion of the pulverized coal gas stream, so that the burner can achieve the high-efficiency burning of the coal powder while reducing the nitrogen oxides in the early stage of anaerobic combustion.

Therefore, the present invention has a strong adaptability to variable coal types. For different coal types, the design of the taper angle and the number of stages of the pulverized coal concentrating ring 6 can control the degree of separation of the pulverized coal; the radial height of the guide vanes 7 and the angle of the guide vanes 7 with the axial angle The design can control the size of the spoiler to the dense phase coal powder; the size of the high temperature recirculation zone can be controlled by the diffuser cone structure 8 of the primary air nozzle. According to the change of coal quality during operation, the swirling intensity of the secondary air can be adjusted by adjusting devices 11 and 12 to meet the requirements of different coal quality ignition and stable combustion.

The invention has the advantages of simple structure, excellent anti-wear performance, strong ignition stability and good coal quality adaptability; Features high efficiency and low NOx emissions.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be limited by the appended claims.

Claims

Rights request:

A dense phase swirling pulverized coal burner characterized by comprising:

a primary air passage (1) provided with the following components in sequence: an elbow section as a pulverized coal inlet, a horizontally disposed straight pipe section, and a primary air vent; an oil disposed on a central shaft in the straight pipe section a gun casing (4), the oil gun casing (4) is provided with a burner ignition oil gun;

The method further includes: a DC secondary air passage (2) disposed around an outer wall of the nozzle of the primary air passage (1); and a swirling secondary air passage (3) surrounding the direct current secondary passage (2) The outer wall of the spout is arranged; the direct current secondary air passage (2) and the swirling secondary air passage (3) are matched in the same large wind box;

Wherein, in the straight pipe section of the primary air passage (1), a plurality of stages of pulverized coal concentration rings (6) are arranged along the axial interval of the oil gun casing (4); (6) is a taper structure disposed around the outer edge of the oil gun casing (4), the opening of the taper is directed toward the spout of the primary air, and the pulverized coal gas stream passes through several stages of expansion cones in the primary wind At the spout, a pulverized coal gas flow distribution is formed.

2. The dense phase swirling pulverized coal burner according to claim 1, wherein

a pulverized coal flow equalizing plate (5) is disposed in the elbow section of the primary air passage (1), and is disposed along a central axis of the curved section, and is divided into two airflow passages in the elbow section;

The pulverized coal equalizing plate (5) has an end located at an inlet of the elbow section, and the other end extends to an outlet of the elbow section, that is, a position where the elbow section communicates with the straight pipe section, so that the pulverized coal gas flows through the After the elbow section, it is evenly distributed in the circumferential direction and enters the straight pipe section.

3. The dense phase swirling pulverized coal burner according to claim 1, wherein

At the spout of the primary air passage (1), a plurality of guide vanes (7) are evenly arranged around the inner wall thereof; the position of the guide vanes (7) and the path region of the dense phase pulverized coal gas flow around the spout Matching, the dense phase pulverized coal gas stream is spoiled and sprayed in a certain direction; and the light phase pulverized coal gas stream in the center of the nozzle is directly sprayed into the outer furnace.

4. The dense phase swirling pulverized coal burner according to claim 1, wherein

The primary air passage (1), the direct current secondary air passage (2), and the outer wall of the swirling secondary air passage (3) are respectively provided with a diffuser structure (8, 9, 10);

The plurality of expanding cone structures (8, 9, 10) respectively have their taper openings arranged in the direction of the outer furnace to delay the mixing time of the secondary air and the primary air.

5. The dense phase swirling pulverized coal burner of claim 1 wherein

The oil gun casing (4) of the straight pipe section is provided with a 2~3 class coal powder concentration ring (6), and the size of the coal powder concentration ring (6) of each stage is enlarged step by step.

6. The dense phase swirling pulverized coal burner according to claim 5, wherein

The taper angle (α) of the pulverized coal concentrating ring (6) of each stage is in the range of 10 ° ~ 25 °.

7. The dense phase swirling pulverized coal burner according to claim 3, wherein

The nozzle of the primary air passage (1) is provided with 10 to 20 of the guide vanes (7) around its inner wall.

8. The dense phase swirling pulverized coal burner according to claim 7, wherein

The angle between each guide vane (7) and the primary air passage (1) is 10° ~ 30°, and the radial height of the guide vane (7) along the primary air passage (1) is the primary air passage (1) ) 0.05 to 0.1 times the diameter.

9. The dense phase swirling pulverized coal burner of claim 4, wherein

The taper angles (β1, β2, β3) of the plurality of expanding cone structures (8, 9, 10) are all less than or equal to 45°.

10. The dense phase swirling pulverized coal burner of claim 1 wherein

An adjustment device (11) for adjusting the air volume is disposed in the DC secondary air passage (2); and an adjustment device (12) for adjusting the intensity of the swirling wind is disposed in the swirling secondary air passage (3).