JP2011127866A - Pulverized coal burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverized coal burner which performs further low NOx combustion by increasing the adjustment width of a mixing state of pulverized coal-mixed flow and secondary air, and obtains the optimum combustion state according to the concentration of the pulverized coal or the quality of coal. <P>SOLUTION: In this pulverized coal burner 5 in which a nozzle body 6 opened toward a furnace 1, has an outer burner nozzle 8 jetting the pulverized coal-mixed flow 14, and an inner burner nozzle 9 concentrically disposed inside the outer burner nozzle, and jetting the tertiary air 27, and a wind box 4 disposed in while surrounding the circumference of the nozzle body and jetting the secondary air 26 from the circumference of the nozzle body, has a secondary air swirling means 24 for giving swirling force to the secondary air, a tertiary air swirling means 19 is disposed inside the inner burner nozzle to give the swirling force to the tertiary air, and the shearing force is acted on the jetted pulverized coal-mixed flow from the inside by the tertiary air, so that the pulverized coal-mixed flow is expanded and diffused to enhance the mixing of the secondary air and the pulverized coal-mixed flow. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pulverized coal burner provided in a furnace such as a coal-fired boiler using pulverized coal as fuel.

  In a furnace that uses fine powder as fuel, for example, a furnace that uses coal as fuel, lump coal is pulverized by a pulverized coal machine (mill) into pulverized coal, and the pulverized coal is mixed with primary air. There is one that is supplied to a pulverized coal burner and ejected from the pulverized coal burner to a furnace to burn the pulverized coal.

  There is a cylindrical burner in one of the pulverized coal burners, in which the outer cylinder nozzle and the inner cylinder nozzle are arranged concentrically in a double circle shape, and an oil burner is arranged on the center axis of the burner, A wind box is provided to surround the outer cylinder nozzle.

  A pulverized coal mixed flow in which pulverized coal and primary air are mixed from the tangential direction flows into the base end of the outer cylinder nozzle, and is ejected from the nozzle tip. The vane box is disposed at predetermined intervals in the circumferential direction. The swirling flow is imparted to the secondary air for combustion by the vanes, and the secondary air is ejected from the periphery of the nozzle tip. The pulverized coal mixed flow ejected from the outer cylinder is mixed with the secondary air and burned.

  Further, tertiary air flows out from the inner cylinder nozzle along the axial center, and the inner cylinder nozzle wall is cooled by the tertiary air.

  In the mixing of the pulverized coal mixed flow and the secondary air, the secondary air is expanded by the centrifugal force of the swirl, and the pulverized coal mixed flow is the swirl flow and the pulverized coal mixed flow given to the secondary air. The pulverized coal mixed flow is spread by following the secondary air by the shearing force, and the pulverized coal is mixed with the secondary air. Therefore, the turning force of the secondary air acts on the mixing of the pulverized coal and the secondary air.

  Furthermore, since the combustion state is determined by the mixed state of the pulverized coal mixed flow and the secondary air, conventionally, the combustion state is controlled by mixing the secondary air with the secondary air by adjusting the vane angle. It is adjusted by changing the turning strength.

  As described above, conventionally, the mixing state is adjusted by the strength of the swirling flow of the secondary air acting from the outer peripheral side of the pulverized coal mixed flow, so the influence of the shear force to the center of the pulverized coal mixed flow. However, the range of adjustment of the mixed state is limited.

Japanese Patent Laid-Open No. 2002-286205 JP 2007-57228 A

  In view of such circumstances, the present invention increases the adjustment range of the mixed state of the pulverized coal mixed flow and the secondary air so that the optimum combustion state can be obtained according to the pulverized coal concentration or the quality of the coal, Furthermore, low NOx combustion is to be realized.

  The present invention includes an outer cylinder nozzle that has a nozzle body that opens toward a furnace and ejects a pulverized coal mixed flow, and an inner cylinder that is provided inside the outer cylinder nozzle concentrically with the outer cylinder nozzle and that ejects tertiary air. A fine powder having a secondary air swirling means that is provided so as to surround the periphery of the nozzle body, and a wind box for ejecting secondary air from the periphery of the nozzle body gives a swirling force to the secondary air. In the charcoal burner, there is a tertiary air swirling means for imparting a swirling force to the tertiary air inside the inner cylinder nozzle, and a shearing force is applied to the spouted pulverized coal mixed flow from the inside by the tertiary air, and the fine powder The present invention relates to a pulverized coal burner configured to expand and diffuse a coal mixed flow to promote mixing of the secondary air and the pulverized coal mixed flow.

  In the present invention, the swirl force given to the secondary air by the secondary air swirl means is variable, the swirl force given to the tertiary air by the tertiary air swirl means is variable, and the pulverized coal mixing is performed by the secondary air. By adjusting the shear force strength given from the outside of the flow and the shear force strength given from the inside of the pulverized coal mixed flow by the tertiary air, the mixing state of the pulverized coal mixed flow and the secondary air is adjusted. The present invention relates to a pulverized coal burner configured to adjust the combustion state.

  Further, the present invention relates to a pulverized coal burner in which the tertiary air swirl means is a screw vane swirl blade provided inside the inner cylinder nozzle.

  Further, according to the present invention, the tertiary air swirling means is a pulverized coal burner which is provided in a circumferential direction on the inner wall surface of the inner cylinder nozzle and is a strip-shaped or substantially strip-shaped swirling blade inclined with respect to the inner cylinder nozzle axis. It is related to.

  Further, the present invention relates to a pulverized coal burner in which the inner cylinder nozzle has a reduced diameter portion whose diameter gradually decreases at the tip, and the swirl vane is provided in the reduced diameter portion and is movable in the axial direction. Is.

  According to the present invention, the tip of the swirl vane is pivotally supported by the inner wall surface of the inner cylinder nozzle, and the base end of the swirl vane is connected to an angle adjustment ring that is rotatably provided. The present invention relates to a pulverized coal burner in which the angle of the swirl blade is adjusted.

  The present invention also relates to a pulverized coal burner configured such that a quaternary air nozzle is provided at the center of the inner cylinder nozzle and quaternary air is ejected from the quaternary air nozzle.

  According to the present invention, the nozzle body that opens toward the furnace is provided with an outer cylinder nozzle that ejects the pulverized coal mixed flow, and is provided concentrically with the outer cylinder nozzle inside the outer cylinder nozzle, and ejects tertiary air. A secondary air swirling means that is provided so as to surround the periphery of the nozzle body, and a wind box that ejects secondary air from the periphery of the nozzle body gives a swirling force to the secondary air. In the pulverized coal burner, having a tertiary air swirling means for imparting a swirling force to the tertiary air inside the inner cylinder nozzle, a shearing force is applied to the jetted pulverized coal mixed flow from the inside by the tertiary air, Since the pulverized coal mixed flow is expanded and diffused to promote the mixing of the secondary air and the pulverized coal mixed flow, the secondary air and the secondary air Mixing with the pulverized coal mixed stream However, the adjustment range of the mixed state is increased, the optimum mixed state according to the load state and coal quality is obtained, and the combustion is controlled only by controlling the air flow, so there is no complicated mechanism and fine powder No wear due to collision with charcoal.

  According to the present invention, the turning force given to the secondary air by the secondary air turning means is variable, the turning force given to the tertiary air is made variable by the tertiary air turning means, and the fine powder is made by the secondary air. The mixing state of the pulverized coal mixed flow and the secondary air is adjusted by adjusting the shearing force strength given from the outside of the coal mixed flow and the shearing force strength given from the inside of the pulverized coal mixed flow by the tertiary air. Therefore, the adjustment range of the mixed state can be increased, and the optimum mixed state can be obtained in accordance with the load state and the quality of coal, and the mixed state, that is, mixing of pulverized coal and combustion air Since the speed can be adjusted, it is possible to adjust the temperature of the flame and the combustion speed, to form an optimum reduction region in the flame, and to realize low NOx combustion.

  According to the present invention, the tertiary air swirling means is a screw blade-shaped swirling blade provided inside the inner cylinder nozzle, and the tertiary air swirling means is circular on the inner wall surface of the inner cylinder nozzle. Since it is a strip-shaped or substantially strip-shaped swirl vane provided in the circumferential direction and inclined with respect to the inner cylinder nozzle axis, no pulverized coal collides with the swirl vane and no wear occurs.

  Further, according to the present invention, the inner cylinder nozzle has a reduced diameter portion with a gradually decreasing diameter at the tip, and the swirl vane is provided in the reduced diameter portion and is movable in the axial direction. The tip of the swirl vane is pivotally supported on the inner wall surface of the inner cylinder nozzle, and the base end of the swirl vane is connected to an angle adjustment ring that is rotatably provided. Since the angle is adjusted, the swirl strength of the tertiary air can be adjusted.

  According to the present invention, since the quaternary air nozzle is provided at the center of the inner cylinder nozzle and the quaternary air is ejected from the quaternary air nozzle, an excellent effect that backfire can be prevented is exhibited.

It is a schematic sectional drawing which shows the 1st Example of this invention. It is a perspective view of the turning blade | wing applied to this 1st Example. (A) (B) (C) (D) is explanatory drawing which shows the behavior of pulverized coal mixed flow, secondary air, tertiary air, and quaternary air in this invention. It is a schematic sectional drawing which shows the 2nd Example of this invention. It is a schematic sectional drawing which shows the 3rd Example of this invention.

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

  A first embodiment of the present invention will be described with reference to FIGS.

  In FIG. 1, reference numeral 1 denotes a furnace, and 2 denotes a furnace wall of the furnace 1.

  A throat 3 is provided on the furnace wall 2, a wind box 4 is attached to the counter-fire furnace 1 side of the furnace wall 2, and a pulverized coal burner 5 is provided concentrically with the throat 3 inside the wind box 4. .

  The pulverized coal burner 5 includes a nozzle body 6 and a secondary air adjusting device 7 provided so as to surround the tip of the nozzle body 6.

  The nozzle body 6 includes an outer cylinder nozzle 8, an inner cylinder nozzle 9 provided concentrically with the outer cylinder nozzle 8, and an oil burner 11 disposed on the center line of the inner cylinder nozzle 9. Between the nozzle 8 and the inner cylinder nozzle 9, a fuel conduction space 12 is formed in a hollow cylindrical space with the furnace 1 side end opened.

  The outer cylinder nozzle 8 and the inner cylinder nozzle 9 have reduced diameter portions 8a and 9a that gradually decrease in diameter at the tip portions, and the tips of the reduced diameter portions 8a and 9a are the same or substantially the same. And has reached just before the throat 3.

  A pulverized coal mixed flow introduction pipe 13 communicates with the base of the outer cylinder nozzle 8 (end on the side of the counter-fired furnace 1), and is conveyed to the primary air and the primary air via the pulverized coal mixed flow introduction pipe 13. The pulverized coal flows as a pulverized coal mixed flow 14 into the fuel conduction space 12 from the tangential direction. The pulverized coal mixed flow 14 flows while turning inside the fuel conduction space 12 and is ejected from the tip of the outer cylinder nozzle 8.

  Further, a tertiary air introduction pipe 15 that opens to the inside of the wind box 4 communicates with the base portion of the inner cylinder nozzle 9, and a part of the combustion air (secondary air) supplied to the wind box 4 is used. The flow rate is adjusted by the intake and the tertiary air flow rate adjusting valve 16 and led to the inner cylinder nozzle 9 as tertiary air.

  A hollow rod 17 is slidably fitted on the oil burner 11, the distal end of the hollow rod 17 reaches the reduced diameter portion 9 a, and the base portion hermetically penetrates the proximal end plate 18 of the nozzle body 6. Exposed.

  A screw blade-shaped swirl vane 19 is provided at the tip of the hollow rod 17 (see FIG. 2). The outer diameter of the swirl vane 19 is larger than the inner diameter of the tip opening of the inner cylinder nozzle 9, It is smaller than the maximum inner diameter of the reduced diameter portion 9a. The swirl vane 19 functions as a swirl force adjusting means for the tertiary air 27 as will be described later.

  An actuator 21, such as a servo cylinder, whose position can be controlled is connected to the base end of the hollow rod 17, and the hollow rod 17 moves forward and backward by driving the actuator 21, and the swirl vane 19 is passed through the hollow rod 17. The position of is changed.

  The secondary air conditioner 7 has an air guide duct 23 whose diameter is reduced toward the tip, and an air volume adjusting blade 24 provided at the base of the air guide duct 23 at equal circumferential intervals. Is rotatable around a rotation shaft 25. The rotary shafts 25 are connected to each other by a link mechanism (not shown), the air volume adjusting blade 24 can be rotated synchronously, and the link mechanism is connected to an air volume adjusting blade driving unit (not shown) to drive the air volume adjusting blade. The angle of the air volume adjusting blade 24 is adjusted by the portion via the link mechanism. The air volume adjusting blade 24 functions as a turning force adjusting means for the secondary air 26.

  Briefly describing the combustion in the pulverized coal burner 5, the pulverized coal mixed stream 14 is supplied from the pulverized coal mixed stream introduction pipe 13 and flows while turning in the fuel conducting space 12, and the fuel conducting space 12. In the process of passing through, the gas is contracted and ejected from the tip of the outer cylinder nozzle 8. Further, secondary air 26 as combustion air is supplied to the wind box 4, and the secondary air 26 is adjusted in turning force or turning force and air volume by the air volume adjusting blade 24. Along with the pulverized coal mixed flow 14 via the guide duct 23, the pulverized coal mixed flow 14 is ejected to the furnace 1 through the throat 3.

  The secondary air 26 taken into the air guide duct 23 from the wind box 4 is given a turning force by the air volume adjusting blades 24 and taken into the air guide duct 23 to obtain the throat as secondary air. 3 is ejected to the furnace 1. By adjusting the turning force of the air volume adjusting blade 24 and adjusting the air volume, the flow state of the supply amount of the secondary air changes, and the combustion state of the fuel is adjusted.

  A part of the secondary air 26 is guided as the tertiary air 27 to the inner cylinder nozzle 9 through the tertiary air introduction pipe 15, and a swirling force is given by the swirl vane 19.

  The turning force applied by the swirl vane 19 is adjusted by the position of the swirl vane 19. That is, when the swirl vane 19 is in the large diameter portion of the reduced diameter portion 9a, the outer diameter of the swirl vane 19 is smaller than the inner diameter of the reduced diameter portion 9a, and the gap around the swirl vane 19 is large. Therefore, the tertiary air 27 flows around the swirl vane 19 having a small resistance, and the swirl force applied by the swirl vane 19 is reduced.

  On the other hand, when the swirl vane 19 is located on the distal end side of the reduced diameter portion 9a and the gap around the swirl vane 19 is small or the swirl vane 19 is in contact with the reduced diameter portion 9a, Most of the tertiary air 27 passes through the swirl vane 19, and the swirl force provided by the swirl vane 19 becomes large.

  Therefore, by controlling the position of the swirl vane 19 by the actuator 21, the strength of the swirl force applied to the tertiary air 27 can be controlled.

  Thus, the combustion state of the fuel is adjusted by the tertiary air 27 ejected from the inner cylinder nozzle 9 to the throat 3.

  The pulverized coal mixed flow 14, the secondary air 26, and the tertiary air 27 are merged at the throat 3, mixed and ejected to the furnace 1, by adjusting the secondary air 26, adjusting the tertiary air 27, etc. The fuel combustion state is adjusted to be optimum.

  The tertiary air flow rate adjustment valve 16 and the actuator 21 are controlled by a control unit 29, and the control unit 29 controls the flow rate by the tertiary air flow rate adjustment valve 16 and the position adjustment of the swirl vane 19 by the control of the actuator 21. Executed.

  In addition, if the set flow rate by the tertiary air flow rate adjustment valve 16 and the position of the swirl blade 19 are determined in advance corresponding to the load state and the quality of coal, when the load state and the quality of coal are determined individually Alternatively, it may be set in advance.

  The oil burner 11 is used when igniting pulverized coal.

  The behavior of the pulverized coal mixed flow 14, the secondary air 26, and the tertiary air 27 will be described with reference to FIG.

  3 (A) to 3 (C) are schematic diagrams showing the behavior of the pulverized coal mixed flow 14, the secondary air 26, and the tertiary air 27 in the throat 3 portion, where ω1 is The swirling strength of the pulverized coal mixed flow 14, ω 2 indicates the swirling strength of the secondary air 26, and ω 3 indicates the swirling strength of the tertiary air 27.

  FIG. 3 (A) shows a case where the swirling strength ω1 of the pulverized coal mixed flow 14 and the swirling strength ω3 of the tertiary air 27 are not large, and between the secondary air 26 and the pulverized coal mixed flow 14, The influence of the shearing force acting between the pulverized coal mixed stream 14 and the tertiary air 27 is small, and the pulverized coal mixed stream 14, the secondary air 26, and the tertiary air 27 travel straight.

  In this case, there is little mixing between the pulverized coal mixed stream 14, the secondary air 26, and the tertiary air 27, especially the mixing of the pulverized coal mixed stream 14 and the secondary air 26 is small, that is, the mixing speed is low. Slow, the combustion speed becomes slow, and the ignition position moves away from the burner nozzle.

  The flow rate of the secondary air 26 and the tertiary air 27 is such that the secondary air 26 is larger than the tertiary air 27, and the pulverized coal mixed stream 14 is combusted mainly by mixing with the secondary air 26. To do.

  FIG. 3B shows a case where a turning force is applied to the secondary air 26 and a turning force applied to the tertiary air 27 is reduced.

  A shearing force acts on the pulverized coal mixed stream 14 by the swirl force of the secondary air 26, and the pulverized coal mixed stream 14 is expanded and diffused by the action of the shearing force, thereby the pulverized coal. Mixing is promoted between the mixed flow 14 and the secondary air 26, and combustion of pulverized coal is promoted. The tertiary air 27 is also expanded by the centrifugal force generated by the turning force of the tertiary air 27 by the shearing force received from the pulverized coal mixed flow 14.

  Due to the expansion of the pulverized coal mixed flow 14 and the tertiary air 27, a circulating flow 28 is generated in the burner shaft center, and the high temperature gas in the furnace is entrained in the flame center, and the temperature of the flame center rises.

  When the temperature at the center of the flame rises, the concentration of pulverized coal is large, and when the amount of pulverized coal in the center of the pulverized coal mixed flow 14 is large, the circulating flow 28 becomes an ignition source, and the pulverized coal mixed flow 14 Combustion delay at the center is suppressed, the ignition position approaches the burner nozzle, and stable combustion occurs.

  FIG. 3C shows a case where a turning force is applied to the secondary air 26 and a turning force applied to the tertiary air 27 is increased.

  When the swirl force of the tertiary air 27 increases, the centrifugal force of the tertiary air 27 expands the tertiary air 27 itself and increases the shearing force acting on the pulverized coal mixed flow 14. The charcoal mixed stream 14 is pushed outward. Therefore, the pulverized coal mixed stream 14 is further expanded by receiving the shearing force from the secondary air 26 and the expanding force and shearing force from the tertiary air 27. The expansion of the pulverized coal mixed stream 14 further promotes the mixing of the pulverized coal mixed stream 14 and the secondary air 26, and the mixing time of the pulverized coal mixed stream 14 and the secondary air 26 is increased. It is shortened and the burning rate is increased.

  Further, when the pulverized coal mixed flow 14 and the tertiary air 27 are further expanded, the circulating flow 28 is also increased, and combustion from the center of the pulverized coal mixed flow 14 is promoted.

  Therefore, in the case of the high-concentration pulverized coal mixed stream 14, the combustion speed of the pulverized coal mixed stream 14 as a whole is increased by the supply of the tertiary air 27 to the center of the inner cylinder nozzle 9 and the ignition action by the circulation flow 28. In addition, stable and uniform combustion is promoted.

  As described above, by adjusting the swirling strength ω2 of the secondary air 26 and the swirling strength of the swirling strength ω3 of the tertiary air 27, the mixing state of the pulverized coal mixed flow 14 and the combustion air can be controlled, Further, by adjusting the swirl strength ω3 of the tertiary air 27, the adjustment range of the mixed state can be increased, and an optimum mixed state in accordance with the load state and the quality of coal can be obtained.

  Furthermore, since the mixing state, that is, the mixing speed of pulverized coal and combustion air can be adjusted, it is possible to adjust the temperature of the flame and the combustion speed, and to form an optimum reduction region in the flame. It is possible to realize NOx combustion.

  In the present invention, since combustion is controlled only by controlling the air flow, there is no complicated mechanism, and wear due to collision with pulverized coal does not occur.

  FIG. 4 shows a second embodiment. 4 that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In the second embodiment, the base end portion 9 b of the inner cylinder nozzle 9 is protruded from the base end plate 18, and a tertiary air introduction pipe 15 is connected to the base end portion 9 b from the tangential direction. The tertiary air 27 is introduced from the tangential direction, and a swirling flow is given to the tertiary air 27 flowing through the inner cylinder nozzle 9. Further, a swirl vane 31 is provided at a required position of the inner cylinder nozzle 9 so that a swirling force is further applied to the tertiary air 27.

  The swirl vanes 31 have a substantially strip shape that is long in the axial direction, and are arranged at predetermined intervals in the circumferential direction. The swirl blade 31 has a front end pivotally supported by the inner cylinder nozzle 9 and is rotatable about the front end. An angle adjustment ring 32 is rotatably fitted to the inner cylinder nozzle 9 on the rear end side of the swirl vane 31, and the rear end of the swirl vane 31 is connected to the angle adjustment ring 32.

  A drive gear 33 is meshed with the inner peripheral side of the angle adjustment ring 32, and the rotation shaft 34 of the drive gear 33 penetrates the base end plate 18 in an airtight manner. Are connected.

  The angle adjustment ring 32 is rotated by rotating the drive gear 33 via the rotation shaft 34 by the motor 35, and the proximal end of the swirl vane 31 is displaced in the circumferential direction, so that the inner cylinder nozzle 9 of the swirl vane 31. The angle with respect to the axis can be adjusted. Further, the turning force of the tertiary air 27 can be adjusted by adjusting the angle of the turning blade 31.

  Also in the present embodiment, the tertiary air 27 ejected from the inner cylinder nozzle 9 has a swirling force and has an action of expanding the pulverized coal mixed flow 14, and the same action as in the second embodiment. , Have an effect.

  When adjusting the turning force of the tertiary air 27, the flow rate of the tertiary air 27 may be adjusted by the tertiary air flow rate adjusting valve 16 in addition to the angle adjustment of the turning blade 31. In this case, the swirl vane 31 and the tertiary air flow rate adjustment valve 16 function as a swirl force adjusting means.

  The angle adjustment of the swirl blade 31 and the flow rate adjustment of the tertiary air flow rate adjustment valve 16 are controlled by the control unit 29.

  FIG. 5 shows a third embodiment. 5 that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In the third embodiment, a quaternary air nozzle 37 is provided at the center of the inner cylinder nozzle 9 so that quaternary air 41 is ejected from the quaternary air nozzle 37.

  The hollow rod 17 is fitted on the quaternary air nozzle 37 and is slidable with the quaternary air nozzle 37 as a central axis. The rear end portion of the quaternary air nozzle 37 further protrudes from the rear end of the hollow rod 17, and a quaternary air flow path 38 is formed between the quaternary air nozzle 37 and the oil burner 11. The rear end of the air flow path 38 is airtightly closed. Further, a quaternary air introduction pipe 39 communicates with the protruding portion of the rear end portion of the quaternary air nozzle 37, and a quaternary air flow rate adjustment valve 40 is provided in the quaternary air introduction pipe 39. The opening degree of the quaternary air flow rate adjusting valve 40 is controlled by the control unit 29, and the air whose flow rate is adjusted by the quaternary air flow rate adjusting valve 40 is guided to the quaternary air nozzle 37 as quaternary air 41.

  Next, the operation of the third embodiment will be described with reference to FIG.

  As described above, by giving a swirl flow to the secondary air 26 and the tertiary air 27, the circulation flow 28 becomes larger and combustion from the center of the pulverized coal mixed flow 14 is promoted. If the flow 28 becomes too large, there is a risk that a flashback phenomenon will occur.

  In this case, the quaternary air nozzle 37 ejects the quaternary air 41 to push back the circulating flow 28, thereby suppressing the occurrence of a backfire phenomenon.

  Thus, by adjusting the swirling force of the secondary air 26 and the tertiary air 27 by the air volume adjusting blade 24 and the swirling blade 19, the amount of ejection of the quaternary air 41 is adjusted to obtain an optimal combustion state. realizable.

DESCRIPTION OF SYMBOLS 1 Furnace 2 Furnace wall 3 Throat 4 Wind box 5 Pulverized coal burner 6 Nozzle body 7 Secondary air adjustment device 8 Outer cylinder nozzle 9 Inner cylinder nozzle 9a Diameter reduction part 14 Pulverized coal mixed flow 16 Tertiary air flow control valve 17 Hollow rod 19 Rotating blade 21 Actuator 24 Air flow adjusting blade 26 Secondary air 27 Tertiary air 29 Control unit 31 Rotating blade 32 Angle adjustment ring 33 Drive gear 34 Rotating shaft 35 Motor 37 Fourth air nozzle 40 Fourth air flow rate adjustment valve 41 Fourth air

Claims (7)

  A nozzle body that opens toward the furnace has an outer cylinder nozzle that ejects a pulverized coal mixed flow, and an inner cylinder nozzle that is provided concentrically with the outer cylinder nozzle inside the outer cylinder nozzle and that ejects tertiary air. And a pulverized coal burner having a secondary air swirling means provided so as to surround the periphery of the nozzle body, and a wind box for ejecting secondary air from the periphery of the nozzle body to impart a swirling force to the secondary air. And a tertiary air swirling means for imparting a swirling force to the tertiary air inside the inner cylinder nozzle, and a shearing force is applied to the jetted pulverized coal mixed flow from the inside by the tertiary air, and the pulverized coal mixed flow is A pulverized coal burner configured to expand and diffuse to promote mixing of the secondary air and the pulverized coal mixed flow.   The swirl force given to the secondary air by the secondary air swirl means is variable, the swirl force given to the tertiary air by the tertiary air swirl means is variable, and is given from the outside of the pulverized coal mixed flow by the secondary air. By adjusting the shear force strength and the shear force strength given from the inside of the pulverized coal mixed flow by the tertiary air, the mixing state of the pulverized coal mixed flow and secondary air is adjusted to adjust the combustion state The pulverized coal burner according to claim 1 configured as described above.   2. The pulverized coal burner according to claim 1, wherein the tertiary air swirling means is a screw blade-shaped swirling blade provided inside the inner cylinder nozzle.   2. The pulverized coal burner according to claim 1, wherein the tertiary air swirling means is a strip-shaped or substantially strip-shaped swirling blade provided in a circumferential direction on the inner wall surface of the inner cylinder nozzle and inclined with respect to the inner cylinder nozzle axis.   3. The pulverized coal burner according to claim 2, wherein the inner cylinder nozzle has a reduced diameter portion whose diameter gradually decreases at a tip portion, and the swirl vane is provided in the reduced diameter portion and is movable in the axial direction.   The tip of the swirl vane is pivotally supported on the inner wall surface of the inner cylinder nozzle, and the base end of the swirl vane is connected to an angle adjusting ring that is rotatably provided. The pulverized coal burner according to claim 4, wherein is adjusted.   The pulverized coal burner according to claim 1, wherein a quaternary air nozzle is provided at the center of the inner cylinder nozzle, and quaternary air is ejected from the quaternary air nozzle.

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