Direct-current burner with adjustable concentration of pulverized coal on fire facing side and method

Abstract

The invention relates to the technical field of direct-current combustors. The direct-current burner comprises a nozzle body arranged at the corresponding corner of a boiler hearth, a spray head arranged at an air outlet of the nozzle body and a blade window separation mechanism, an elbow is arranged in the middle of the nozzle body, primary inertial concentration is carried out when pulverized coal airflow passes through, and the concentration a of the fire-facing side is improved; the blade window separation mechanism is arranged in the spray head, and secondary adjustable concentration is carried out when pulverized coal airflow passes through the blade window separation mechanism. When the boiler is in a low-load operation state, the elbow can enable coarse particle pulverized coal with the particle size larger than 50 micrometers to be enriched in a wall-attached mode, high-concentration wall-attached flow with the thickness larger than or equal to 50 mm is formed, and the concentration is 80%-100% higher than that of main flow; the stable combustion of the boiler in a rated load range of 15%-100% can be realized through the adjustment of the control piece; and when the load is low (less than or equal to 30% of rated load), the smoke temperature at the outlet of the hearth is increased by 30-50 DEG C, the ignition condition is improved, the smoke temperature at the inlet of the SCR denitration system is maintained to be more than or equal to 300 DEG C, and the NOx emission concentration is controlled to be below 50mg / m.

Description

Technical Field

[0001] This invention relates to the field of DC burner technology, specifically a DC burner and method with adjustable coal powder concentration on the fire side. Background Technology

[0002] New energy refers to renewable energy sources, whose intermittent and fluctuating output poses a challenge to the stability of the power system. Coal-fired boilers, as the traditional main power source, need to compensate for the fluctuations in new energy output through peak-shaving methods such as deep load reduction and rapid start-up and shutdown to ensure the balance of power grid supply and demand. In coal-fired boiler power generation technology, the four-corner (or octagonal) tangential boiler is the main combustion equipment, with direct-current burners arranged at the four corners (or octagons) of the boiler furnace. High-speed pulverized coal gas flow is injected into the furnace after passing through the direct-current burners, forming a tangentially shaped gas flow convergence field. During this process, the pulverized coal gas flow on the fire side (a) is directly impacted by the high-temperature flame at the upstream adjacent corner, achieving rapid ignition. Simultaneously, the four-corner (or octagonal) jets support each other through airflow coupling, ultimately forming a rotating and stable combustion flame, ensuring efficient combustion of the boiler under rated operating conditions.

[0003] When the boiler operates at high load (>50% of rated load), the furnace temperature is high (typically ≥1200℃), providing excellent pulverized coal ignition conditions. However, as the boiler load decreases, the furnace temperature also drops, and the ignition conditions deteriorate accordingly. Specifically, without fuel oil assistance, the minimum stable combustion load can only be maintained at 30%-40% of the rated load, while deep peak shaving in the power system requires a minimum stable combustion load ≤30% of the rated load. When the furnace temperature drops to 600-900℃, far below the critical ignition temperature of pulverized coal (typically >900℃), and the proportion of pulverized coal in the primary air-coal mixture is insufficient (typically 0.3-0.5 kg pulverized coal / kg air), the heat required for ignition cannot be replenished in time, delaying pulverized coal ignition. Current technologies rely on external heating methods such as micro-oil ignition and plasma combustion assistance; this not only incurs high operating costs (annual combustion assistance costs for a 300MW unit exceed 2 million yuan) but also presents system complexity and a high risk of failure.

[0004] In existing technologies, louvered horizontal pulverized coal burners, while achieving pulverized coal concentration separation through internal guide vanes and injecting over 70% of the pulverized coal into the furnace via the rich side outlet, cannot adjust the concentration of pulverized coal on either the rich or single side. This results in a lower pulverized coal concentration on the fire-facing side (a) of the direct-flow burner nozzle. Therefore, without fuel oil assistance and relying entirely on pulverized coal combustion, this type of burner cannot achieve stable boiler operation within the 20%-30% rated load range, making it difficult to meet deep peak-shaving requirements. Furthermore, under low-load conditions, the burner's ability to suppress NOx formation is weakened due to factors such as reduced reductive properties and increased air-coal ratio, leading to higher NOx formation rates.

[0005] In summary, under conditions without fuel oil assistance, existing DC burners exhibit issues such as pulverized coal ignition delay and NO2 under 20%-30% rated load. x The problems include high production volume and insufficient combustion stability. Summary of the Invention

[0006] The purpose of this invention is to provide a DC burner and method with adjustable coal powder concentration on the fire side, so as to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a direct-flow burner with adjustable pulverized coal concentration on the fire side, comprising: The nozzle body is used to be arranged at the corresponding corner of the boiler furnace. The middle part is bent. When the pulverized coal airflow passes through, it performs primary inertial concentration to increase the concentration of α on the fire side. The nozzle is located at the air outlet of the nozzle body; The blade separation mechanism is installed inside the nozzle and performs two-stage adjustable concentration when the pulverized coal gas flows through it. The blade separation mechanism includes a series of blades and an operating element. The series of blades is located inside the nozzle, and the operating element passes through the nozzle body and is connected to the series of blades to drive the series of blades to translate along the nozzle axis.

[0008] Furthermore, the nozzle includes a DC primary air nozzle b, the end of the nozzle away from the nozzle body is the DC primary air nozzle b, and the nozzle has a rectangular inner cavity at the end near the DC primary air nozzle b.

[0009] Furthermore, a conical blunt body is provided in the rectangular inner cavity, and the narrow end of the conical blunt body points to the series blade group; when the two-stage adjustable concentrated pulverized coal airflow passes through the conical blunt body, it is distributed on both sides of the concentration.

[0010] Furthermore, it also includes a deflector plate, which is obliquely disposed inside the nozzle and located between the leaflet separation mechanism and the conical blunt body, for increasing the concentration of a on the fire side.

[0011] Furthermore, the tandem blade group includes several vertically arranged blades, each blade comprising a first-stage blade, a second-stage blade, and a third-stage blade, which are fixed sequentially on the control element.

[0012] Furthermore, the control element comprises a crossbar, a U-shaped rod, and an operating lever. Two adjacent blades are fixedly connected by the crossbar, and the first-stage blade is connected to the third-stage blade via the U-shaped rod. One end of the operating lever is fixedly connected to the U-shaped rod, and the other end extends to the outside of the nozzle body.

[0013] Furthermore, the translation range of the tandem blade group is 0.5-1d, where 0.5d is located between 1d and the DC primary air nozzle b.

[0014] Furthermore, the airflow at the nozzle body inlet is 14-30 m / s.

[0015] Furthermore, the adjustment range of the tandem blade group includes 0.85-1d, 0.75-0.85d, 0.65-0.75d, and 0.5-0.65d.

[0016] A method of using a direct-flow burner with adjustable pulverized coal concentration on the fire side, the method comprising: Step 1: Determine the boiler load operating status, which includes above 50% rated load, 30%-50% rated load, 20%-30% rated load, and below 20% rated load; Step 2: Determine the appropriate state for the DC burner based on the boiler load operation status. This state includes weakened concentration function, medium concentration function, deep concentration function, and extreme concentration function. Step 3: Adjust the position of the series blade group according to the required state of the DC burner. This position includes 0.85-1d, 0.75-0.85d, 0.65-0.75d and 0.5-0.65d.

[0017] Compared with the prior art, the beneficial effects of the present invention are: The present invention includes a nozzle body arranged at the corresponding corner of the boiler furnace, a nozzle head and a blade separation mechanism set at the air outlet of the nozzle body. The nozzle body has a bend in the middle, which performs primary inertial concentration when the pulverized coal airflow passes through, thereby increasing the concentration of α on the fire side. The blade separation mechanism is set inside the nozzle head, which performs secondary adjustable concentration when the pulverized coal airflow passes through. This invention controls the pulverized coal concentration at the DC primary air nozzle b within the range of 0.3-0.75 kg pulverized coal / kg air, meeting the combustion requirements across the entire load range. Even under low-load boiler operation, the elbow allows coarse pulverized coal particles with a diameter >50 μm to adhere to the wall and accumulate, forming a high-concentration wall-adhering flow with a thickness ≥50 mm, which is 80%-100% higher than the mainstream concentration. The end of the tandem blade assembly 30, located away from the DC primary air nozzle b within the L range, can guide more than 70% of the high-concentration pulverized coal to the concentrated side n, thereby improving the ignition conditions at the DC primary air nozzle b. Subsequently, through adjustment of the control components, stable combustion of the boiler can be achieved within the 15%-100% rated load range. Under low load (≤30% rated load), the flue gas temperature at the furnace outlet increases by 30-50℃, the flue gas temperature at the SCR denitrification system inlet remains ≥300℃, and NO... x Emission concentrations should be controlled below 50 mg / m³. Attached Figure Description

[0018] Figure 1 This is a top sectional view of the present invention; Figure 2 This is a top view schematic diagram of the four burners arranged at the four corners of the boiler furnace in this invention; Figure 3 This is a top sectional view of the leaf window separation mechanism in this invention at position 0.5d; Figure 4 This is a front view of the DC primary air nozzle b in this invention; Figure 5 This is a schematic diagram of the result of the leaf window separation mechanism in this invention; In the diagram: 1. Nozzle body; 2. Nozzle head; 3. Blade separation mechanism; 4. Rectangular inner cavity; 5. Conical blunt body; 6. Guide plate; 30. Tandem blade assembly; 31. Control element; 11. Elbow; 301, First-stage blade; 302, Second-stage blade; 303, Third-stage blade; 311, Crossbar; 312, U-shaped rod; 303, Operating lever. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figures 1-5 The present invention provides a technical solution: a DC burner with adjustable pulverized coal concentration on the fire side, comprising: Nozzle body 1 is used to be arranged at the corresponding corner of the boiler furnace. The middle part is an elbow 11, which performs primary inertial concentration when the pulverized coal gas flows through it, thereby increasing the concentration of a on the fire side. Nozzle 2 is located at the air outlet of nozzle body 1; The blade separation mechanism 3 is installed inside the nozzle 2 and performs two-stage adjustable concentration when the pulverized coal gas flows through it. The blade separation mechanism 3 includes a series blade group 30 and an operating element 31. The series blade group 30 is located inside the nozzle 2. The operating element 31 passes through the nozzle body 1 and is connected to the series blade group 30 to drive the series blade group 30 to translate along the axis of the nozzle 2.

[0021] The nozzle 2 includes a DC primary air nozzle b, and the end of the nozzle 2 away from the nozzle body 1 is the DC primary air nozzle b. The nozzle 2 has a rectangular inner cavity 4 at the end near the DC primary air nozzle b.

[0022] The rectangular inner cavity 4 is provided with a conical blunt body 5, the narrow end of which points towards the series blade group 30; when the two-stage adjustable concentrated coal powder airflow passes through the conical blunt body 5, it is distributed on both sides of the concentrated and diluted sides.

[0023] It also includes a guide plate 6, which is inclinedly disposed inside the nozzle 2 and located between the leaflet separation mechanism 3 and the conical blunt body 5, for increasing the concentration of a on the fire side.

[0024] Figure 2 In a tangential pulverized coal combustion boiler, four burners are arranged at the four corners of the boiler furnace. Under the condition of no fuel oil assistance, the high-speed pulverized coal airflow enters the nozzle body 1 through inlet a. The airflow velocity can be adjusted from 14 to 30 m / s to meet the rigid airflow requirements under different loads. Then, primary inertial concentration is performed: the middle of nozzle body 1 is a bend 11; at the inlet of bend 11, utilizing the density difference between pulverized coal particles and air, high-concentration pulverized coal particles have greater inertia than gas and fine particles; because the high-concentration coarse particles have greater inertia, they are difficult to change direction sharply with the airflow at bend 11, and will continue to move in a straight line along the original trend (i.e., the tangential direction of the outlet of bend 11), directly impacting the wall surface, and impacting the outer wall of bend 11 tangentially. After losing kinetic energy, under the impetus of gravity and subsequent airflow, a high-concentration pulverized coal area is formed near the wall surface, while the airflow away from the wall surface is mainly composed of lower-concentration air and fine powder. After passing through bend 11, the high-speed pulverized coal airflow completes the initial concentration stratification, that is, the side close to the wall surface is the direct primary air concentrated side n direction, and the side away from the wall surface is the direct primary air depleted side m direction.

[0025] In one embodiment, the tandem blade assembly 30 includes a plurality of vertically arranged blades, each blade comprising a first-stage blade 301, a second-stage blade 302, and a third-stage blade 303, which are sequentially fixed to the actuating member 31. The translation range of the tandem blade assembly 30 is 0.5-1d, where 0.5d is located between 1d and the direct current primary air nozzle b. The airflow at the inlet of the nozzle body 1 is 14-30 m / s. The adjustment range of the tandem blade assembly 30 includes 0.85-1d, 0.75-0.85d, 0.65-0.75d, and 0.5-0.65d.

[0026] Figure 1 and Figure 5After the first-stage inertial concentration, a second-stage adjustable concentration is carried out: the blade separation mechanism 3 is set in the nozzle 2. The high-speed pulverized coal airflow enters the nozzle 2 through the elbow 11 and flows through the blade separation mechanism 3. Through the shielding and guiding effect of the series blade group 30, the airflow on the rich and poor sides diffuses to increase the concentration on the fire side a, creating favorable conditions for subsequent ignition. In the second-stage adjustable concentration process, the diffusion intensity of the airflow on the rich and poor sides can be changed by controlling the linear translation of the series blade group 30 according to the boiler load operation, thereby adjusting the air-coal ratio at the direct primary air nozzle b of the nozzle 2 to achieve enrichment effect under different loads.

[0027] The arrangement of the series blade group 30 in the nozzle 2 is as follows: the first-stage blade 301, the second-stage blade 302, and the third-stage blade 303 are arranged in a stepped sequence, with the blades perpendicular to the ground. That is, with the outlet plane P1 of the DC primary air dilute side m as the reference, the control element 31 is directly and rigidly connected to the center of the first-stage blade 301, the second-stage blade 302, and the third-stage blade 303 in sequence to form the "series blade group 30". Figure 1 The range and direction of the linear translation of the series blade group 30 are as follows: The series blade group 30 is driven to translate linearly by the linear translation of the control element 31. The series blade group 30 can move within the range L along the axis of the nozzle 2, where L = 0.5-1d. 0.5d is the closest position to the outlet of the DC primary air nozzle b, and 1d is the farthest position from the outlet of the DC primary air nozzle b.

[0028] When adjustment is required, the control element 31 drives the blade assembly to move within a range of 0.5-1d along the axis of the nozzle 2. Through the shielding and guiding effect of the series blade assembly 30, the diffusion distance of the rich and lean airflow is long when the series blade assembly 30 is far away from the outlet of the DC primary air nozzle b; when the series blade assembly 30 is close to the outlet of the DC primary air nozzle b, the diffusion distance of the rich and lean airflow is short. This further guides the concentrated pulverized coal airflow after the first stage to the rich side n and the lean pulverized coal airflow to the lean side m, completing the second stage of blade separation. Finally, the airflow is injected into the furnace through the DC primary air nozzle b, enhancing the pulverized coal enrichment effect on the fire side a and ensuring stable combustion throughout the entire load range.

[0029] A rectangular inner cavity 4 is provided inside the nozzle 2 at one end near the DC primary air nozzle b, for reference. Figure 4 A conical blunt body 5 is provided in the rectangular inner cavity 4, and the narrow end of the conical blunt body 5 points to the series blade group 30; when the coal powder airflow passes through the conical blunt body 5 after completing the secondary blade separation, it is distributed on both sides with varying concentrations.

[0030] In one embodiment, the control element 31 comprises a crossbar 311, a U-shaped rod 312, and an operating rod 313. Two adjacent blades are fixedly connected by the crossbar 311, and the first-stage blade 301 is connected to the third-stage blade 303 by the U-shaped rod 312. One end of the operating rod 313 is fixedly connected to the U-shaped rod 312, and the other end extends to the outside of the nozzle body 1.

[0031] This design, for reference Figure 5 The control element 31 consists of a crossbar 311, a U-shaped rod 312, and an operating lever 313. Adjacent blades are fixedly connected via the crossbar 311, and the first-stage blade 301 is connected to the third-stage blade 303 via the U-shaped rod 312. One end of the operating lever 313 is fixedly connected to the U-shaped rod 312, and the other end extends to the outside of the nozzle body 1 to connect with an external linear power device, such as a cylinder. The cylinder should be placed in a space with a suitable temperature. The nozzle body 1 has a through hole (not shown in the figure), and the operating lever 313 is slidably disposed within the through hole, with a sealed connection between the operating lever 313 and the through hole.

[0032] This invention enables the pulverized coal concentration at the DC primary air nozzle b to be controlled within the range of 0.3-0.75 kg pulverized coal / kg air, meeting the combustion requirements across the entire load range. Even when the boiler is operating at low load, the elbow 11 can cause coarse pulverized coal particles with a particle size >50μm to adhere to the wall and accumulate, forming a high-concentration wall-adhering flow with a thickness ≥50mm, which is 80%-100% higher than the mainstream concentration; the tandem blade assembly 30, located at the end furthest from the DC primary air nozzle b within the L range, can guide more than 70% of the high-concentration pulverized coal to the concentrated side n, thereby improving the ignition conditions at the DC primary air nozzle b.

[0033] A method of using a direct-flow burner with adjustable pulverized coal concentration on the fire side, the method comprising: Step 1: Determine the boiler load operating status, which includes above 50% rated load, 30%-50% rated load, 20%-30% rated load, and below 20% rated load; Step 2: Determine the appropriate state for the DC burner based on the boiler load operation status. This state includes weakened concentration function, medium concentration function, deep concentration function, and extreme concentration function. Step 3: Adjust the position of the series blade group 30 according to the required state of the DC burner. This position includes 0.85-1d, 0.75-0.85d, 0.65-0.75d and 0.5-0.65d.

[0034] Specifically, the method includes: Step 1: When the boiler is operating at high load (>50% of rated load), the furnace temperature is high (usually ≥1200℃), providing excellent pulverized coal ignition conditions. The system focuses on improving burnout rate and operational economy. Through the control element 31 and its weakened concentration function: the system drives the control element 31 to move the series blade assembly 30 along the thick-lean separation outlet plane reference to the 0.85-1d range. At this point, the blade assembly has the strongest effect on airflow diffusion. Over 90% of the primary air-pulverized coal airflow (including initially stratified lean pulverized coal and some thick pulverized coal) can directly pass through the blade gaps. Airflow equalization is achieved only through slight guidance from the blades, avoiding excessive concentration that could lead to slagging or NO buildup at the direct primary air nozzle b. x The generation rate surges; ensure that the primary airflow passes through the DC primary air nozzle b at a high speed of 25-30 m / s, and that the jet rigidity is ≥800 Pa. m forms a stable imaginary tangential circle at the center of the furnace. At this time, the pulverized coal concentration at the outlet of the DC primary air nozzle b is maintained at 0.3-0.4 kg pulverized coal / kg air to ensure complete combustion of pulverized coal, balancing economy and combustion stability.

[0035] Step 2: When the boiler load drops to 30%-50% of the rated load and the furnace temperature drops to 900-1200℃, the ignition conditions weaken, and the medium concentration function needs to be activated by the control component 31: The system drives the control component 31 to move the series blade group 30 along the reference plane of the thick and thin separation outlet towards the outlet of the DC primary air nozzle b, and finally stabilizes in the range of 0.75-0.85d. At this time, the diffusion effect of the blade group on the airflow is weakened, so that the coal powder concentration ratio on the thick and thin side reaches 2:1-3:1, completing the secondary high-efficiency separation; the airflow velocity on the thick side is reduced to 20-25m / s (15%-20% lower than the thin side), which prolongs the residence time of coal powder on the fire-facing side a (≥0.5s) and enhances the enrichment of coal powder. At this time, the concentration of pulverized coal on the rich side (n) of the DC primary air nozzle (b) is increased to 0.5-0.6 kg pulverized coal / kg air, while the concentration on the light side (m) is maintained at 0.2-0.3 kg pulverized coal / kg air. The rich pulverized coal ignites preferentially to form a stable root flame, with flame fluctuation amplitude ≤ ±5%, balancing the stable combustion requirement and operating efficiency.

[0036] Step 3: When the boiler load drops to 20%-30% of the rated load, the furnace temperature further drops to 600-900℃, and the ignition conditions are harsh. Deep concentration needs to be achieved through the control component 31 to maximize the stable combustion effect: The system drives the control component 31 to move the series blade group 30 along the reference plane of the thick and thin separation outlet towards the outlet direction of the DC primary air nozzle b, and finally stabilizes in the range of 0.65-0.75d. At this time, the diffusion effect of the blade group on the airflow in the direction of m on the thin side is further weakened, and the concentration ratio of the thick and thin sides reaches 4:1-5:1, maximizing the secondary concentration efficiency; the airflow velocity drops to 15-20m / s (30%-40% lower than the medium load), and the concentrated coal powder is highly enriched on the fire side a. At this time, the concentration of pulverized coal on the rich side (n) of the DC primary air nozzle (b) increases to 0.65-0.75 kg pulverized coal / kg air, while the concentration on the light side (m) decreases to 0.15-0.25 kg pulverized coal / kg air. The high-concentration pulverized coal ignites rapidly on the fire-facing side (a) (ignition delay time ≤ 0.3s), forming a stable high-temperature flare and achieving oil-free stable combustion.

[0037] Step 4: When the boiler load drops below 20% of the rated load and the furnace temperature is ≤600℃, extreme concentration adjustment needs to be performed through the control component 31 to meet the deep peak shaving requirements: The control component 31 maintains a stable state after being driven, and the series blade group 30 remains in the range of 0.5-0.65d to minimize the diffusion effect on the airflow and ensure that all the coal powder with a high concentration difference on the rich and lean sides is directed to the outlet of the DC primary air nozzle b; the airflow velocity drops to 14-16m / s (design lower limit) to provide a stable high-temperature environment for coal powder ignition. At this time, the coal powder concentration on the rich side n at the outlet of the DC primary air nozzle b is maintained at 0.7-0.75kg coal powder / kg air, and the concentration on the lean side m is as low as 0.1-0.15kg coal powder / kg air; after the high-concentration, low-velocity coal powder airflow enters the furnace, it ignites immediately under the high temperature of the fire-facing side a, achieving oil-free stable combustion at ultra-low load, with the lower limit of stable combustion load ≤15% of the rated load, meeting the deep peak shaving requirements.

[0038] By adjusting the control element 31, stable combustion of the boiler can be achieved within the range of 15%-100% rated load; at low load (≤30% rated load), the flue gas temperature at the furnace outlet increases by 30-50℃, and the flue gas temperature at the inlet of the SCR denitrification system is maintained at ≥300℃, NO x Emission concentrations should be controlled below 50 mg / m³.

[0039] Table of Corresponding DC Burner Matching States for Boiler Load Operating Status:

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0041] It should be noted that if the embodiments of the invention involve directional indicators (such as up and down), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0042] Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Additionally, if the embodiments of the invention involve descriptions such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, "multiple" refers to two or more.

[0043] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

Claims

1. A direct flow burner with adjustable coal dust concentration on the fire side, characterized in that, The utility model relates to a kind of straight-flow pulverized coal burner, including: Nozzle body (1) is used to be arranged in the corresponding angle of boiler furnace, wherein the part is elbow (11), and primary inertia concentration is carried out when pulverized coal gas stream passes, and the concentration of side a to fire is improved; Spray head (2) is arranged at the air outlet of nozzle body (1); Leaf window separation mechanism (3) is arranged in spray head (2), and secondary adjustable concentration is carried out when pulverized coal gas stream passes;The leaf window separation mechanism (3) includes series blade group (30) and operating device (31), the series blade group (30) is located in spray head (2), and the operating device (31) is connected with series blade group (30) after penetrating the nozzle body (1), for driving series blade group (30) to translate along the axis direction of spray head (2).

2. The direct flow burner with adjustable coal dust concentration on the fire side according to claim 1, characterized in that, The spray head (2) includes straight-flow primary air nozzle b, and the end of the spray head (2) away from the nozzle body (1) is the straight-flow primary air nozzle b, and a rectangular inner cavity (4) is arranged at the end of the spray head (2) close to the straight-flow primary air nozzle b.

3. The direct flow burner with adjustable coal powder concentration on the fire side according to claim 2, characterized in that, A conical bluff body (5) is arranged in the rectangular inner cavity (4), and the narrow end of the conical bluff body (5) points to the series blade group (30); when the pulverized coal gas stream passes through the conical bluff body (5), the secondary adjustable concentration is completed, and the pulverized coal gas stream is distributed on both sides of the thick and thin sides.

4. The direct flow burner with adjustable coal powder concentration on the fire side according to claim 3, characterized in that, It also includes a guide vane (6), which is inclinedly arranged in the spray head (2) and located between the leaf window separation mechanism (3) and the conical bluff body (5), for improving the concentration of side a to fire.

5. The direct flow burner with adjustable coal concentration on the fire side according to claim 1, characterized in that, The series blade group (30) includes a plurality of blades arranged vertically, and the blades include primary blades (301), secondary blades (302) and tertiary blades (303), which are sequentially fixed on the operating device (31).

6. The direct flow burner with adjustable coal dust concentration on the fire side according to claim 5, characterized in that, The operating device (31) is a cross bar (311), a U-shaped rod (312) and an operating rod (313), and the adjacent two blades are fixedly connected by the cross bar (311), and the primary blades (301) are connected with the tertiary blades (303) by the U-shaped rod (312); one end of the operating rod (313) is fixedly connected with the U-shaped rod (312), and the other end extends to the outside of the nozzle body (1).

7. The direct flow burner with adjustable coal concentration on the fire side according to claim 5, characterized in that, The translation range of the series blade group (30) is 0.5-1d, and 0.5d is located between 1d and the straight-flow primary air nozzle b.

8. The direct flow burner with adjustable coal concentration on the fire side according to claim 1, characterized in that, The air flow at the air inlet of the nozzle body (1) is 14-30 m / s.

9. The direct flow burner with adjustable coal concentration on the fire side according to claim 5, characterized in that, The adjustment range of the series blade group (30) includes 0.85-1d range, 0.75-0.85d range, 0.65-0.75d range and 0.5-0.65d range.

10. A method for using the direct-flow burner with adjustable coal dust concentration on the fire side, applied to the direct-flow burner according to any one of claims 1-9, characterized in that, The method includes: Step one, determine the boiler load operating state, which includes 50% rated load or more, 30%-50% rated load, 20%-30% rated load and 20% rated load or less; Step two, determine the state required to cooperate according to the boiler load operating state, which includes weakening concentration function, moderate concentration function, deep concentration function and limit concentration function. Step three, adjust the position of the series blade set (30) according to the state of matching required by the direct current combustor, the position including 0.85-1d, 0.75-0.85d, 0.65-0.75d and 0.5-0.65d.

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