JP6070240B2 - Pulverized coal burner - Google Patents

Description

  The present invention relates to a pulverized coal burner that is provided on the wall of a boiler furnace and burns pulverized coal, and more particularly to a pulverized coal burner having a plasma torch for pulverized coal ignition.

  Some pulverized coal burners use a plasma torch as means for igniting pulverized coal. The plasma torch generates high-temperature plasma, so it can be easily applied to pulverized coal with a low volatile content. By using a plasma torch, the fuel supply system does not require an oil supply system, and pulverized coal can be supplied. One system can be used, and the equipment can be simplified. In addition, since the plasma is high temperature, it is possible to start in a state where the furnace is cold, that is, to start a cold can.

  However, when a plasma torch is used as the ignition means, there is a problem in the stability of ignition and the stability of the flame formed because the high temperature region formed by the plasma is narrow.

  In Patent Document 1, a plasma torch is incorporated in the center of a pulverized coal combustion burner having a burner tile, pulverized coal and primary air are blown into the high temperature portion of the plasma jet, and secondary air is swirled so as to surround the plasma jet. A burner for a plasma assisted combustion furnace that completely burns pulverized coal by supplying the pulverized coal is disclosed.

JP-A-6-265109

  In view of such circumstances, the present invention provides a pulverized coal burner that improves the stability of ignition at start-up and the stability of flames formed in a normal furnace.

  The present invention includes an outer cylinder nozzle that opens toward the furnace and ejects while swirling a pulverized coal mixed flow in which pulverized coal and conveying air are mixed, and is concentric with the outer cylinder nozzle inside the outer cylinder nozzle. A nozzle main body having an inner cylinder nozzle for ejecting auxiliary combustion air, a secondary air adjusting device for ejecting combustion air from the periphery of the nozzle main body, and a plasma torch for ejecting plasma, The outer cylinder nozzle is provided with a stagnation part forming member that forms a part of the inner surface so as to be displaceable. A stagnation part that increases the pulverized coal concentration is formed by the displacement of the stagnation part forming member, and is ejected from the stagnation part. The present invention relates to a pulverized coal burner in which the plasma torch is disposed so as to eject plasma into the pulverized coal mixed flow.

  The present invention also includes a plurality of deflector angles provided along the axial direction provided on the inner surface of the outer cylinder nozzle, and a semicircle formed on the inner surface of the outer cylinder nozzle and capable of rotating the stay portion forming member. The stay portion forming member is further formed with a curved surface having the same curvature as the inner surface of the outer cylinder nozzle on one surface, and a protrusion projecting toward the axial center from the deflector angle on the other surface. The present invention relates to a pulverized coal burner in which a portion is formed.

  According to the present invention, a concave groove is further formed on the inner surface of the outer cylinder nozzle, and the retention portion forming member can be inserted into and removed from the concave groove, and a contact portion of the retention portion forming member and the concave groove is contacted. This relates to a pulverized coal burner having the same parts.

  Furthermore, the present invention further includes a recess formed on the inner surface of the outer cylinder nozzle, into which the staying part forming member can be fitted, and the staying part forming member has the same curvature as the inner surface of the outer cylinder nozzle. A curved surface is formed and is rotatable, and the stay portion forming member is related to a pulverized coal burner that protrudes toward the inner cylinder nozzle by rotating.

  According to the present invention, an outer cylinder nozzle that opens toward the furnace and jets while swirling a pulverized coal mixed flow in which pulverized coal and conveying air are mixed, and the outer cylinder nozzle inside the outer cylinder nozzle A nozzle body having an inner cylinder nozzle that is concentrically provided and ejects auxiliary combustion air, a secondary air adjustment device that ejects combustion air from the periphery of the nozzle body, and a plasma torch that ejects plasma The outer cylinder nozzle is provided with a stagnation part forming member that forms a part of the inner surface in a displaceable manner, and a stagnation part that increases the pulverized coal concentration is formed by the displacement of the stagnation part forming member. Since the plasma torch is disposed so as to eject plasma into the pulverized coal mixed flow to be ejected, when the furnace is at a low temperature, the staying part forming member is displaced to form the staying part, High temperature region by plasma By passing the high-concentration pulverized coal mixed flow, the ignition stability of the pulverized coal can be improved, and when the temperature in the furnace is sufficiently increased, By using a part of the inner surface of the outer cylinder nozzle, the pulverized coal mixed flow can be made into a uniform swirl flow, and the excellent effect that the stability of the flame formed in the furnace can be improved. Demonstrate.

1 is a schematic vertical sectional view showing a pulverized coal burner according to a first embodiment of the present invention. It is explanatory drawing which shows the structure of the retention part formation member which concerns on 1st Example of this invention, and its peripheral part, (A) shows the case where this retention part formation member is made into a part of inner surface of an outer cylinder nozzle. , (B) shows a case where a staying part is formed by the staying part forming member. It is a schematic elevation sectional drawing which shows the pulverized coal burner which concerns on the 2nd Example of this invention. It is explanatory drawing which shows the structure of the retention part formation member which concerns on 2nd Example of this invention, and its peripheral part, (A) shows the case where this retention part formation member is made into a part of inner surface of an outer cylinder nozzle. , (B) shows a case where a staying part is formed by the staying part forming member. It is explanatory drawing which shows the structure of the retention part formation member which concerns on 3rd Example of this invention, and its peripheral part, (A) shows the case where this retention part formation member is made into a part of inner surface of an outer cylinder nozzle. , (B) shows a case where a staying part is formed by the staying part forming member.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the pulverized coal burner 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2A and 2B.

  In FIG. 1, 2 is a furnace of a boiler (not shown), and 3 is a furnace wall of the furnace 2. A throat 4 is provided on the furnace wall 3, a wind box 5 is attached to the counter-fire furnace 2 side of the furnace wall 3, and the pulverized coal burner 1 is provided concentrically with the throat 4 inside the wind box 5. Yes.

  The pulverized coal burner 1 has a nozzle body 6 on the center axis of the pulverized coal burner 1, is connected to the throat 4, and is provided so as to surround the tip of the nozzle body 6. A secondary air conditioner 7 concentric with the main body 6 is provided.

  The nozzle body 6 includes an outer cylinder nozzle 8 and an inner cylinder nozzle 9 provided concentrically with the outer cylinder nozzle 8, and between the outer cylinder nozzle 8 and the inner cylinder nozzle 9, A fuel-conducting space 11 having an open end at the furnace 2 side is formed in a hollow cylindrical space.

  On the inner peripheral surface of the outer cylinder nozzle 8, deflector angles 12 having a triangular shape in cross section are disposed at a predetermined number of pitches in the circumferential direction at a predetermined angle pitch, for example, 45 ° intervals. Yes. Also, between one of the deflector angles 12 and the deflector angle 12 adjacent to the deflector angle 12 (between the uppermost deflector angle 12 and the deflector angle 12 adjacent to the deflector angle 12 in the drawing). Is formed with a semi-cylindrical concave groove 13 having a predetermined length in the axial direction, and a retention portion forming member 14 is rotatably provided around the axial center of the concave groove 13. ing. A rotation drive shaft 10 is connected to the staying portion forming member 14, and the rotation drive shaft 10 passes through the window box 5 and extends to the outside of the window box 5. A driving means (not shown) is connected to the shaft end of the rotary drive shaft 10.

  The stay portion forming member 14 has a curved surface having the same curvature (including the same or substantially the same) as the outer cylinder nozzle 8 on one surface, and a projecting portion 15 having a triangular cross section, for example, is formed on the other surface. . When one surface of the retention portion forming member 14 is exposed in the fuel conduction space 11, as shown in FIG. 2A, the inner surface of the outer cylinder nozzle 8 and one surface of the retention portion forming member 14 are provided. And the stay portion forming member 14 becomes a part of the inner surface of the outer cylinder nozzle 8.

  Further, when the other surface of the staying portion forming member 14 is exposed to the fuel conducting space 11, the projecting portion 15 is more axial than the deflector angle 12 as shown in FIG. It protrudes toward That is, the height of the protrusion 15 is higher than the deflector angle 12. Note that the axial length of the protruding portion 15 is sufficient to form a staying portion 16 to be described later.

  A pulverized coal mixed flow introduction pipe 17 communicates with the base of the outer cylinder nozzle 8 (the end on the side of the counter-fired furnace 2) from the tangential direction. The pulverized coal mixed flow introduction pipe 17 is connected to a pulverized coal mill (not shown), and the pulverized coal mixed flow introduction pipe 17 is mixed with primary air, which is conveying air, and pulverized coal. The charcoal mixed flow 18 flows into the fuel conduction space 11 from the tangential direction.

  The pulverized coal mixed flow 18 flows toward the front end side while turning inside the fuel conduction space 11. The pulverized coal mixed flow 18 is jetted from the outer cylinder nozzle 8 (the furnace 2 side end) while forming the staying portion 16 in which the pulverized coal concentration is increased by the protrusion 15 during the flow process. It has become.

  Further, a plasma torch 19 is provided outside the outer cylinder nozzle 8 so as to penetrate the window box 5. The plasma torch 19 is inclined so as to gradually approach the outer cylinder nozzle 8 toward the tip, and the tip of the plasma torch 19 is located in the vicinity of the tip of the staying portion 16.

  A secondary air blowing duct 21 communicates with the window box 5, and secondary air 22 as combustion air flows into the window box 5 through the secondary air blowing duct 21.

  Further, one end of a tertiary air introduction pipe 23 communicates with the base portion of the inner cylinder nozzle 9, and the other end opens inside the wind box 5. The tertiary air introduction pipe 23 is provided with a tertiary air flow rate adjustment valve 24. The tertiary air introduction pipe 23 takes in a part of the secondary air 22 from the window box 5, adjusts the flow rate by the tertiary air flow rate adjusting valve 24, and forms the tertiary air 25 as auxiliary combustion air as the tertiary air 25. It leads into the inner cylinder nozzle 9.

  The secondary air adjusting device 7 includes an auxiliary air adjusting mechanism 26 that houses the tip of the nozzle body 6, and a main air adjusting mechanism 27 that is provided concentrically outside the auxiliary air adjusting mechanism 26. Yes.

  The auxiliary air adjusting mechanism 26 includes a first air guide duct 28 that is reduced in diameter toward the tip, and a large number of inner air vanes 29 that are rotatably provided at equal circumferential intervals. Can be rotated synchronously via a link mechanism (not shown), and the inclination angle with respect to the air flow can be changed. The main air adjustment mechanism 27 includes a second air guide duct 31 that is reduced in diameter toward the tip, and a plurality of outer air vanes 32 that are rotatably provided at equal circumferential intervals, and all the outer air Like the inner air vane 29, the vane 32 can be rotated synchronously via a link mechanism (not shown), and the inclination angle with respect to the air flow can be changed.

  The tip of the second air guide duct 31 is continuous with the throat 4, and the tip of the first air guide duct 28 is in a position retracted from the inner wall surface of the furnace wall 3, and the outer cylinder nozzle 8, The tip of the inner cylinder nozzle 9 is also at a position retracted from the inner wall surface of the furnace wall 3.

  Next, combustion in the pulverized coal burner 1 when a boiler (not shown) having a low temperature in the furnace 2 is started (when a cold can is started) will be described.

  The pulverized coal pulverized by a pulverized coal mill (not shown) is conveyed by primary air, and is supplied as the pulverized coal mixed flow 18 from the pulverized coal mixed flow introduction pipe 17 to the base of the fuel conduction space 11. The pulverized coal mixed stream 18 flows toward the furnace 2 while turning in the fuel conduction space 11.

  In the course of flowing in the fuel conduction space 11, the pulverized coal mixed stream 18 is made uniform in the pulverized coal concentration in the pulverized coal mixed stream 18 by the deflector angle 12, and swirling is suppressed to the axial direction. Given speed. At this time, the other portion of the staying portion forming member 14 is exposed in the fuel conduction space 11 (see FIG. 2B), and the pulverized coal mixed flow 18 swirled by the protruding portion 15 is Due to the damming, a part of the pulverized coal mixed flow 18 stays, and the staying part 16 in which the pulverized coal concentration is increased is formed adjacent to the protruding part 15.

  When the pulverized coal mixed flow 18 is ejected from the tip of the outer cylinder nozzle 8, the high-concentration pulverized coal mixed flow in which the plasma ejected from the plasma torch 19 is ejected from the tip of the staying portion 16. 18 and pulverized coal is ignited.

  Further, the secondary air 22 as combustion air is supplied to the window box 5, and the secondary air 22 is adjusted in turning force or turning force and air volume by the outer air vane 32. 2 is sent to the throat 4 through the air guide duct 31.

  A part of the secondary air 22 taken into the second air guide duct 31 is taken into the first air guide duct 28 via the inner air vane 29 and used for secondary auxiliary combustion. Spouted as air. The inner air vane 29 is inclined with respect to the air flow, and adjusts the swirl force or swirl force and air volume of a part of the taken-in secondary air 22.

  By adjusting the turning force and air volume by the outer air vane 32 and by adjusting the turning force and air volume by the inner air vane 29, the supply amount and flow state of the secondary air 22 change, and the combustion state of pulverized coal is adjusted. Is done.

  A part of the secondary air 22 is taken in as the tertiary air 25 through the tertiary air introduction pipe 23. The tertiary air 25 flows through the inner cylinder nozzle 9 and is ejected from the tip of the inner cylinder nozzle 9 to the throat 4.

  The combustion state of pulverized coal is adjusted by ejecting the tertiary air 25. Therefore, the combustion state of the pulverized coal is adjusted to be optimum by adjusting the secondary air 22 and the tertiary air 25.

  Further, when the temperature of the furnace 2 is sufficiently increased, the staying portion forming member 14 is rotated so that one surface of the staying portion forming member 14 is exposed in the fuel conduction space 11 by driving means (not shown). The

  One surface of the stay portion forming member 14 has the same curvature as the inner surface of the outer cylinder nozzle 8, and the inner surface of the outer tube nozzle 8 and one surface of the stay portion forming member 14 are flush with each other (FIG. 2). (See (A)), the staying portion 16 is not formed, and a uniform swirling flow is formed by the pulverized coal mixed flow 18.

  As described above, in the first embodiment, a curved surface having the same curvature as the inner surface of the outer cylinder nozzle 8 is formed on one surface of the staying portion forming member 14 rotatably provided in the recess 13. The protrusion 15 is formed on the other surface so as to protrude from the deflector angle 12.

  When the boiler having a low temperature in the furnace 2 is started (when the cold can is started), the pulverized coal is caused to protrude by the projecting portion 15 by exposing the other surface of the stay portion forming member 14 in the fuel conduction space 11. Since the mixed flow 18 is retained to form the retaining portion 16, and a large amount of pulverized coal (high concentration pulverized coal mixed flow) can be passed through a high temperature region formed by plasma, the ignition stability of the pulverized coal is improved. It can be improved, and stable ignitability of pulverized coal can be obtained.

  When the temperature of the furnace 2 is sufficiently increased, the staying part forming member 14 is rotated by the driving means (not shown) via the rotary drive shaft 10 so that one surface of the staying part forming member 14 is moved. By exposing in the fuel conduction space 11, the pulverized coal mixed flow 18 can be a uniform swirling flow without uneven flow, and the stability of the flame formed in the furnace 2 can be improved. .

  Next, the pulverized coal burner 1 according to the second embodiment of the present invention will be described with reference to FIGS. 3, 4A and 4B. In FIGS. 3, 4A, and B, the same components as those in FIGS. 1 and 2A and 2B are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, between one of the deflector angles 12 on the inner surface of the outer cylinder nozzle 8 and the deflector angle 12 adjacent to the deflector angle 12 (the topmost deflector angle 12 and the deflector angle 12 in the figure). For example, a semi-cylindrical concave groove 33 having a predetermined length in the axial direction is formed between the deflector angle 12 and the adjacent deflector angle 12. A retaining portion forming member 34 having the same shape as the recessed groove 33 is provided in the recessed groove 33 so as to be insertable / removable in the axial direction, and the slide shaft 30 is connected to the retaining portion forming member 34. The slide shaft 30 passes through the window box 5, and advancing / retreating drive means (not shown) is provided at the shaft end of the slide shaft 30. The plasma torch 19 is disposed so that the tip of the plasma torch 19 is positioned in the vicinity of the tip of the concave groove 33.

  As shown in FIG. 4A, the staying part forming member 34 has a curved surface having the same curvature as the inner surface of the outer cylinder nozzle 8, and is moved into the groove 33 by the advance / retreat driving means. When inserted, the inner surface of the outer cylinder nozzle 8 and the staying portion forming member 34 are substantially flush with each other, and the staying portion forming member 34 becomes a part of the inner surface of the outer tube nozzle 8. ing.

  Further, as shown in FIG. 4B, when the stay portion forming member 34 is pulled out from the groove 33 through the slide shaft 30 by the advance / retreat driving means, the groove 33 Are exposed in the fuel conduction space 11. As the pulverized coal mixed flow 18 flows into the exposed concave groove 33, a part of the pulverized coal mixed flow 18 stays in the concave groove 33, and the pulverized coal concentration increases in the concave groove 33. A staying portion 16 is formed.

  When pulverized coal is burned by the pulverized coal burner 1 when the boiler in the furnace 2 having a low temperature is started, the stay portion forming member 34 is removed from the concave groove 33 by advancing / retreating drive means (not shown). The retention portion 16 is formed in the concave groove 33.

  By intersecting the high-concentration pulverized coal mixed flow 18 ejected from the tip of the staying portion 16 and the plasma ejected from the plasma torch 19, a high-temperature region formed by the plasma can be treated with a large amount of pulverized coal ( High-concentration pulverized coal mixed flow) passes, and the ignitability of the pulverized coal is improved. Even when the temperature in the furnace 2 is low, stable ignitability of the pulverized coal can be obtained.

  Further, when the temperature in the furnace 2 rises sufficiently, the stay portion forming member 34 is inserted into the concave groove 33 by the advance / retreat driving means. By inserting the stay portion forming member 34, the stay portion forming member 34 becomes substantially flush with the inner surface of the outer cylinder nozzle 8, so that the pulverized coal mixed flow 18 is made into a uniform swirling flow without uneven flow. The stability of the flame formed in the furnace 2 can be improved.

  In the second embodiment, the retention portion forming member 34 has the same shape as the concave groove 33, but the concave groove 33 is closed when inserted and is substantially flush with the inner surface of the outer cylinder nozzle 8. Any other shape may be used.

  Next, a pulverized coal burner 1 according to a third embodiment of the present invention will be described with reference to FIGS. In FIGS. 5A and 5B, the same components as those in FIGS. 2A and 2B are denoted by the same reference numerals, and the description thereof is omitted.

  In the third embodiment, a substantially rectangular concave portion 35 having a predetermined length in the axial direction is formed between the deflector angles 12 and 12 on the inner surface of the outer cylinder nozzle 8. For example, a substantially rectangular stay portion forming member 36 can be fitted into the recess portion 35.

  The stay portion forming member 36 is rotatable around a rotation shaft 37 parallel to the inner surface of the outer cylinder nozzle 8, and the stay portion forming member 36 is rotated by driving means (not shown). The stay portion forming member 36 projects into the fuel conduction space 11 toward the inner cylinder nozzle 9.

  Further, as shown in FIG. 5A, the staying portion forming member 36 has a curved surface having the same curvature as the inner surface of the outer cylinder nozzle 8, and the rotating shaft 37 is moved by the driving means. The inner surface of the outer cylinder nozzle 8 and the retention portion forming member 36 are substantially flush with each other, and the retention portion forming member 36 is in contact with the outer cylinder nozzle 8. It becomes to become a part of the inside.

  Further, as shown in FIG. 5B, when the staying portion forming member 36 is rotated, the staying portion forming member 36 protrudes into the fuel conduction space 11, and the pulverized coal mixed flow 18 is As part of the pulverized coal mixed stream 18 is retained by the stagnation of the stagnation part forming member 36, the stagnation part 16 having an increased pulverized coal concentration adjacent to the stagnation part forming member 36 is formed. It has become.

  When pulverized coal is burned by the pulverized coal burner 1 at the time of boiler startup (at the time of cold can startup) where the temperature in the furnace 2 is low, it is driven via the rotary shaft 37 by driving means (not shown). The stay part forming member 36 is rotated and protruded into the fuel conduction space 11 to form the stay part 16 adjacent to the stay part forming member 36.

  By intersecting the high-concentration pulverized coal mixed flow 18 ejected from the tip of the staying portion 16 with the plasma ejected from the plasma torch 19, a large amount of pulverized coal is produced in a high temperature region formed by the plasma. Even if the ignitability of the pulverized coal is improved and the temperature in the furnace 2 is low, the stable ignitability of the pulverized coal can be obtained.

  Further, when the temperature in the furnace 2 rises sufficiently, the staying portion forming member 36 is rotated by the driving means via the rotating shaft 37 and is fitted in the recess 35. By fitting the staying part forming member 36, the staying part forming member 36 is substantially flush with the inner surface of the outer cylinder nozzle 8, so that the pulverized coal mixed flow 18 is uniformly swirled without drift. And the stability of the flame formed in the furnace 2 can be improved.

  In the third embodiment, the staying portion forming member 36 is substantially rectangular. However, when the retaining portion forming member 36 is fitted to the concave portion 35, it is substantially flush with the inner surface of the outer cylinder nozzle 8, and at the time of rotation, the pulverized coal mixed flow Other shapes may be used as long as the retaining portion 16 can be formed by damming 18.

  Further, in the first to third embodiments, the pulverized coal can be stably ignited even when the boiler 2 has a low temperature in the furnace 2 (when the cold can is started). Therefore, an oil burner or the like for raising the temperature of the furnace 2 at the time of starting the boiler is not necessary, and the production cost and fuel cost can be reduced.

  Further, in the first to third embodiments, the case where the plasma torch 19 is used as the igniting means of pulverized coal has been described. However, when means other than plasma are used as the igniting means, or brown coal Even in the case of burning low-grade coal such as the above, by forming the staying portion 16 and forming a region where the pulverized coal concentration is increased, ignition stability and stability of the flame formed in the furnace 2 are improved. It is possible to improve the performance.

  In the first to third embodiments, the plasma torch 19 is provided around the outer cylinder nozzle 8 through the window box 5, but the plasma torch 19 is a plasma. The pulverized coal mixed flow 18 whose concentration has been increased in the staying portion 16 may be provided so as to pass through the inner cylinder nozzle 9 with the plasma torch 19 inclined, for example. It may be inserted.

DESCRIPTION OF SYMBOLS 1 Pulverized coal burner 2 Furnace 6 Nozzle body 7 Secondary air conditioner 8 Outer cylinder nozzle 9 Inner cylinder nozzle 11 Fuel conduction space 12 Deflector angle 13 Concave groove 14 Retention part forming member 15 Protrusion part 16 Retention part 18 Pulverized coal mixed flow 19 Plasma torch 22 Secondary air 25 Tertiary air 33 Groove 34 Retention part forming member 35 Recess 36 Retention part forming member

Claims (4)

  An outer cylinder nozzle that opens toward the furnace and spouts while swirling a pulverized coal mixed flow in which pulverized coal and transport air are mixed, and an auxiliary cylinder nozzle that is provided concentrically with the outer cylinder nozzle inside the outer cylinder nozzle The outer cylinder nozzle, comprising: a nozzle body having an inner cylinder nozzle for ejecting combustion air; a secondary air adjusting device for ejecting combustion air from the periphery of the nozzle body; and a plasma torch for ejecting plasma. A stagnation part forming member that forms a part of the inner surface is provided to be displaceable, a stagnation part that increases the pulverized coal concentration is formed by the displacement of the stagnation part forming member, and the pulverized coal ejected from the stagnation part A pulverized coal burner, characterized in that the plasma torch is disposed so as to eject plasma into a mixed flow.   A plurality of deflector angles provided on the inner surface of the outer cylinder nozzle and extending along the axial direction; a semi-cylindrical groove formed on the inner surface of the outer cylinder nozzle and capable of rotating the stay portion forming member; Further, the stay portion forming member has a curved surface having the same curvature as the inner surface of the outer cylinder nozzle on one surface, and a projecting portion projecting toward the axial center from the deflector angle on the other surface. The pulverized coal burner according to claim 1.   A concave groove is further formed on the inner surface of the outer cylinder nozzle, and the retention portion forming member can be inserted into and removed from the concave groove, and the portion where the retention portion forming member contacts and the portion where the concave groove contacts are the same. The pulverized coal burner according to claim 1.   The concave portion is further formed on the inner surface of the outer cylinder nozzle and into which the retention portion forming member can be fitted. The retention portion forming member has a curved surface having the same curvature as the inner surface of the outer cylinder nozzle. The pulverized coal burner according to claim 1, wherein the pulverized coal burner is rotatable, and the stay forming member protrudes toward the inner cylinder nozzle by rotating.

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