JP5678603B2 - Pulverized coal burner - Google Patents

Description

  The present invention relates to a pulverized coal burner equipped with a plasma torch for pulverized coal ignition.

  Some pulverized coal burners use a plasma torch for ignition of 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. The system and system can be improved, and the equipment can be simplified.

  Moreover, there exists a thing shown by patent document 1 as a pulverized coal burner. In the pulverized coal burner of Patent Document 1, an ignition burner inserted obliquely with respect to the pulverized coal burner is provided, and it is shown that a plasma torch is used as the ignition burner.

  In patent document 1, since a plasma does not contact the whole pulverized coal flow with respect to the pulverized coal flow blown out in a ring shape and ignition may be performed locally, more stable ignitability is required. .

Japanese Patent Laid-Open No. 11-354290

  In view of such circumstances, the present invention is intended to obtain stable ignition performance in a pulverized coal burner equipped with a plasma torch for pulverized coal ignition.

  In the present invention, an inner cylinder nozzle is provided concentrically with the nozzle body inside the nozzle body, a cylindrical fuel conduction space is formed between the inner cylinder nozzle and the nozzle body, and the fuel conduction space is interposed therebetween. A pulverized coal mixed flow is ejected, and a secondary air adjusting device is provided so as to surround the tip of the nozzle body, and secondary air is ejected from the periphery of the nozzle body through the secondary air adjusting device. A pulverized coal burner comprising a plasma torch at the center of the inner cylinder nozzle, the plasma torch forms plasma in front of the nozzle body, and the pulverized coal mixed flow ejected from the nozzle body intersects the plasma. It relates to the pulverized coal burner.

  The present invention further includes a plasma diffusion means, which relates to a pulverized coal burner for diffusing the plasma in the radial direction.

  Further, in the present invention, the plasma diffusion means is an air ejection nozzle provided in the inner cylinder nozzle in parallel with the plasma torch. The air ejection nozzle intersects with the plasma and extends outward from the center. The present invention relates to a pulverized coal burner that ejects air and diffuses plasma in a radial direction.

  According to the present invention, the plasma diffusion means is a plasma diffusion plate provided so as to cross the plasma in front of the plasma torch, and the plasma collides with the plasma diffusion plate and diffuses in the radial direction. It concerns the burner.

  According to the present invention, the plasma diffusing means comprises a plurality of plasma torches, and the plasma torches relate to a pulverized coal burner that forms plasma radially outward.

  In the present invention, the tip of the nozzle body and the tip of the inner cylinder nozzle form a pulverized coal mixed flow outlet flow passage that is reduced in diameter toward the tip, and circulates through the pulverized coal mixed flow outlet passage. The reduced pulverized coal mixed flow relates to a pulverized coal burner that intersects the plasma.

  According to the present invention, an inner cylinder nozzle is provided concentrically with the nozzle body inside the nozzle body, a cylindrical fuel conduction space is formed between the inner cylinder nozzle and the nozzle body, and the fuel conduction space. A pulverized coal mixed flow is ejected through the nozzle, a secondary air adjusting device is provided so as to surround the tip of the nozzle body, and secondary air is supplied from the periphery of the nozzle body through the secondary air adjusting device. A pulverized coal burner to be ejected, comprising a plasma torch at the center of the inner cylinder nozzle, the plasma torch forming plasma in front of the nozzle body, and the pulverized coal mixed flow ejected from the nozzle body is the plasma Therefore, the pulverized coal is reliably ignited by contact with the high-temperature plasma, and the plasma is formed at the center of the pulverized coal mixed flow. Performance There is exhibited an excellent effect that is.

(A) is a schematic sectional drawing of the pulverized coal burner which concerns on a 1st Example, (B) is A arrow directional view of FIG. 1 (A). It is a schematic sectional drawing of the pulverized coal burner which concerns on a 2nd Example. (A) is a schematic sectional drawing of the pulverized coal burner which concerns on a 3rd Example, (B) is a B arrow line view of FIG. 3 (A). It is a schematic sectional drawing of the pulverized coal burner which concerns on a 4th Example. (A) is a schematic sectional drawing of the pulverized coal burner which concerns on a 5th Example, (B) is C arrow line view of FIG. 5 (A).

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

  First, a first embodiment of the present invention will be described with reference to FIG.

  In FIG. 1A, 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 inner cylinder nozzle 9 provided concentrically with the nozzle body 6, and a plasma torch 11 disposed on the center line of the inner cylinder nozzle 9. The number of air ejection nozzles 12 of the required number (four in the figure, see FIG. 1B) is arranged at an equiangular pitch (90 degrees in the figure) on the circumference centered on the center line of the plasma torch 11. It is installed.

  A fuel conduction space 10 is formed between the nozzle body 6 and the inner cylinder nozzle 9 in a hollow cylindrical space with the furnace 1 side end opened. The nozzle body 6 has a reduced diameter portion 6a that gradually decreases in diameter at the tip.

  A pulverized coal mixed flow introduction pipe 13 communicates with the base of the nozzle body 6 (the end on the side of the counter-fired furnace 1), and primary powder and fine powder conveyed to the primary air through the pulverized coal mixed flow introduction pipe 13. Charcoal flows into the fuel conduction space 10 from the tangential direction as a pulverized coal mixed flow 14. The pulverized coal mixed flow 14 flows while turning inside the fuel conduction space 10 and is ejected from the tip of the nozzle body 6.

  A tertiary air introduction pipe 15 that opens to the inside of the wind box 4 communicates with a base portion of the inner cylinder nozzle 9, and a part of combustion air (secondary air 16) supplied to the wind box 4 is taken in. The third air 28 is led to the inner cylinder nozzle 9.

  The base end portion of the plasma torch 11 protrudes through the base end surface of the inner cylinder nozzle 9, and plasma generating air is supplied from the protruding base end portion via the first air supply line 17, A plasma power source 18 is connected to the plasma torch 11 so that power necessary for plasma excitation is supplied from the plasma power source 18.

  A base end portion of the air ejection nozzle 12 protrudes through the base end surface of the inner cylinder nozzle 9 and is connected to the manifold 19. Accordingly, all the air ejection nozzles 12 communicate with each other via the manifold 19. The manifold 19 is connected to an air supply source (not shown) via a second air supply line 21.

  The tip of the air ejection nozzle 12 has a shape cut obliquely with respect to the axis, and the tip surface 12a is an ellipse that is inclined with respect to the axis and is a plane that faces the axis. Further, a plurality of air jet holes 22 are formed in the front end surface 12a so as to eject air in a direction perpendicular to or substantially perpendicular to the front end surface 12a. Further, the perpendiculars passing through the centers of the front end surfaces 12a of the four air ejection nozzles 12 are different in directions by 90 ° as shown in FIG. 1B, and are eccentric from the axis of the inner cylinder nozzle 9 by a required distance. Pass through the position. That is, the plasma diffusion air 20 ejected from the window box 4 is dispersed radially after passing through the vicinity of the center of the inner cylinder nozzle 9 without interfering with each other. Note that the tip surface 12a shown in FIG. 1B is a view seen from the vertical direction only on the tip surface in order to clarify the orientation of the tip surface.

  The air ejection nozzle 12 that passes through the vicinity of the center line of the plasma torch 11 and ejects air radially functions as plasma diffusion means as will be described later.

  The secondary air conditioner 7 has an air guide duct 23 that is reduced in diameter 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 blades 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 blades. The angle of the air volume adjusting blade 24 is adjusted by the portion via the link mechanism.

  The combustion in the pulverized coal burner 5 will be briefly described.

  First, ignition of the pulverized coal burner 5 will be described.

  Plasma generation air is supplied from the first air supply line 17 and excitation power is supplied to the plasma power source 18 to generate plasma 27 from the tip of the plasma torch 11. The plasma 27 is formed so as to extend in front of the nozzle body 6 toward the core side by the flow of air for generating plasma. In a state in which the plasma 27 is stable, air is supplied to the air ejection nozzle 12 through the second air supply line 21, and the plasma diffusion air 20 is ejected from the air ejection hole 22 of the distal end surface 12a.

  Since the plasma diffusion air 20 is scattered radially across the plasma 27, the plasma 27 is affected by the flow of the plasma diffusion air 20 and diffuses in the radial direction with respect to the axis of the nozzle body 6 (see FIG. 1 (A) indicated by 27a). The range of diffusion is preferably widened over the entire pulverized coal outlet of the nozzle body 6. Accordingly, the supply amount of air for generating plasma to the plasma torch 11 and the discharge of the plasma diffusion air 20 from the plasma torch 11 so that the plasma 27 a spreads over the entire pulverized coal outlet of the nozzle body 6. Adjust the amount.

  The pulverized coal mixed flow 14 is supplied from the pulverized coal mixed flow introduction pipe 13, flows while swirling in the fuel conduction space 10, and is compressed in the process of passing through the fuel conduction space 10, and the nozzle body 6 It is ejected from the tip of. 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. 3 is ejected to the furnace 1.

  The pulverized coal flow ejected from the tip of the nozzle body 6 crosses the diffused plasma 27a. In the process of crossing, the pulverized coal comes into contact with the high temperature plasma 27a and ignites. Since the plasma is at a high temperature of 3000 ° C., it is ignited reliably even when the secondary air 16 is pulverized coal with little volatile content and the secondary air 16 is at a low temperature (normal temperature). Further, since the plasma 27a spreads over the entire pulverized coal outlet, the pulverized coal flow is ignited evenly throughout.

  The ignition by the plasma torch 11 is continued until the temperature of the furnace 1 rises to a predetermined temperature, and when the self-sustained combustion (steady combustion) is possible with the pulverized coal burner 5 alone, Occurrence is stopped. When the steady combustion state is reached, the plasma torch 11 and the air jet nozzle 12 may be moved backward so as not to receive radiant heat from the inside of the furnace.

  Further, the combustion state of the fuel is adjusted by the tertiary air 28 ejected from the inner cylinder nozzle 9 to the throat 3.

  Thus, in the above embodiment, since it is not necessary to use oil for ignition, a single fuel supply system may be used, and stable ignition performance can be obtained.

  A second embodiment will be described with reference to FIG.

  In FIG. 2, the same components as those shown in FIG. 1A are denoted by the same reference numerals, and description thereof is omitted.

  In the second embodiment, the air ejection nozzle 12 used in the first embodiment is omitted, and a plasma diffusion plate 31 is used as the plasma diffusion means.

  The plasma torch 11 is provided on the center line of the inner cylinder nozzle 9, and the plasma diffusion plate 31 is supported at a position away from the tip of the plasma torch 11 by a required distance on the extension of the center line of the plasma torch 11.

  The plasma diffusion plate 31 is provided so as to be orthogonal to the center line of the plasma torch 11 and cross the plasma 27, and the plasma diffusion plate 31 is formed by three or four columns 32 of the inner cylinder nozzle 9. Installed at the tip. The plasma diffusion plate 31 and the support column 32 are made of a material that can withstand the high temperature of plasma, for example, ceramic.

  In the second embodiment, the plasma 27 ejected from the tip of the plasma torch 11 collides with the plasma diffusion plate 31 and spreads in the radial direction. The pulverized coal mixed flow 14 ejected from the tip of the nozzle body 6 traverses the plasma 27 spread, and the pulverized coal comes into contact with the plasma 27 and ignites.

  Also in the second embodiment, since it is not necessary to use oil for ignition, the fuel supply system may be one series, and the entire pulverized coal mixed stream 14 is in contact with the plasma 27, so that stable ignition performance is achieved. can get.

  A third embodiment will be described with reference to FIG.

  In FIG. 3A, the same components as those shown in FIG. 1A are denoted by the same reference numerals, and the description thereof is omitted.

  In the third embodiment, the air ejection nozzle 12 used in the first embodiment is omitted, a plurality of plasma torches 11 are provided, and a function as plasma diffusion means is added to the plasma torch 11 itself.

  A plurality of plasma torches 11 (four in the figure, see FIG. 3B) are arranged along the center line of the inner cylinder nozzle 9, and the plasma generation direction is inclined outward from the axial direction. In addition, the inclination direction is shifted by 90 ° for each plasma torch 11.

  By generating the plasma 27 from the plasma torch 11 while being inclined outward, the pulverized coal mixed stream 14 is ejected across the plasma 27, and the pulverized coal contacts the plasma 27. set a fire.

  The number of the plasma torches 11 is set so that the pulverized coal mixed flow 14 ejected in a link shape from the nozzle body 6 is in contact with the plasma 27 evenly.

  In the case of the third embodiment, the plasma torch 11 may be moved backward to protect against radiant heat from the furnace when steady combustion with pulverized coal is possible.

  In FIG. 3A, in order to clarify the plasma generation direction, the tip of the plasma torch 11 is cut obliquely with respect to the axis, but the shape of the tip is not limited. . 3B, as in FIG. 1B, in order to clarify the direction of the tip surface 11a, only the tip surface is viewed from the vertical direction.

  A fourth embodiment will be described with reference to FIG.

  In the fourth embodiment, the pulverized coal mixed stream 14 is compressed toward the center so that the pulverized coal mixed stream 14 ejected from the nozzle body 6 contacts the plasma 27.

  A reduced diameter portion 9a whose diameter decreases toward the distal end side is formed at the distal end portion of the inner cylinder nozzle 9, and a reduced diameter portion 6a whose diameter decreases toward the distal end side is formed at the distal end portion of the nozzle body 6. . The diameter-reduced portion 6a and the diameter-reduced portion 9a form a truncated pulverized coal mixed flow outlet channel 34 that has a truncated cone shape that decreases in diameter toward the tip.

  The pulverized coal mixed flow 14 flows through the pulverized coal mixed flow outlet flow path 34, so that the pulverized coal mixed flow 14 contracts toward the center and intersects with the plasma formed in front of the plasma torch 11. The position where the pulverized coal mixed flow 14 is most contracted is preferably a portion where the plasma 27 is generated.

  When the pulverized coal mixed flow 14 intersects the plasma 27, the pulverized coal comes into contact with the plasma 27 and ignites. Since the pulverized coal mixed stream 14 intersects or contacts the plasma 27 at the position where the pulverized coal mixed flow 14 is contracted, the ejected pulverized coal uniformly contacts the plasma 27 and ignites, and stable ignition performance is obtained.

  A fifth embodiment will be described with reference to FIG.

  In the fifth embodiment, a plurality of plasma torches 11 are provided outside the pulverized coal burner 5.

  A plurality of, in this embodiment, four plasma torches 11 are inclined with respect to the axis of the pulverized coal burner 5 so that the extension of the axis of the plasma torch 11 faces the axis of the pulverized coal burner 5. The plasma torch 11 is provided so that the tip of the plasma torch 11 is positioned at the tip of the nozzle body 6. Further, the direction in which the plasma 27 formed in front of the front end of the plasma torch 11 intersects the flow of the pulverized coal mixed flow 14 which is ejected in a ring shape from the front end of the nozzle body 6. Further, as seen in FIG. 5 (B), it is made to follow the circumferential flow of the ring-shaped flow formed by the pulverized coal mixed flow 14. For example, the plasma 27 is ejected so as to contact the center circle 35 of the ring-shaped flow.

  Accordingly, the four plasmas 27 traverse the ring-shaped flow of the pulverized coal mixed flow 14 over the entire circumference, and the pulverized coal mixed flow 14 comes into contact with any of the plasmas 27, and pulverized powder. Charcoal is ignited by the plasma 27. Also in the fifth embodiment, the ejected pulverized coal uniformly ignites upon contact with the plasma 27, and a stable ignition performance is obtained.

DESCRIPTION OF SYMBOLS 1 Furnace 2 Furnace wall 3 Throat 5 Pulverized coal burner 6 Nozzle body 7 Secondary air conditioner 9 Inner cylinder nozzle 10 Fuel conduction space 11 Plasma torch 12 Air ejection nozzle 13 Pulverized coal mixed flow introduction pipe 14 Pulverized coal mixed flow 16 Secondary Air 18 Power source for plasma 20 Plasma diffusion air 27 Plasma 31 Plasma diffusion plate 32 Strut 34 Pulverized coal mixed flow outlet flow path 35 Center circle

Claims (3)

An inner cylinder nozzle is provided inside the nozzle body concentrically with the nozzle body, and a cylindrical fuel conduction space is formed between the inner cylinder nozzle and the nozzle body, and pulverized coal mixing is performed via the fuel conduction space. A pulverized coal burner in which a secondary air adjusting device is provided so that a flow is jetted and surrounds the tip of the nozzle body, and secondary air is jetted from the periphery of the nozzle body through the secondary air adjusting device A plasma torch at the center of the inner cylinder nozzle, and an air jet nozzle provided in parallel with the plasma torch inside the inner cylinder nozzle, the plasma torch forming plasma in front of the nozzle body and, said air ejection nozzle intersecting the plasma, the air ejected toward the outer side from the center, to diffuse the plasma radially pulverized coal mixture flow ejected from the nozzle body the Pulverized coal burner, characterized in that intersects the plasma. An inner cylinder nozzle is provided inside the nozzle body concentrically with the nozzle body, and a cylindrical fuel conduction space is formed between the inner cylinder nozzle and the nozzle body, and pulverized coal mixing is performed via the fuel conduction space. A pulverized coal burner in which a secondary air adjusting device is provided so that a flow is jetted and surrounds the tip of the nozzle body, and secondary air is jetted from the periphery of the nozzle body through the secondary air adjusting device A plasma torch that forms plasma in front of the nozzle body at the center of the inner cylinder nozzle, and a plasma diffusion plate that crosses the plasma is provided in front of the plasma torch, the plasma being the plasma diffusion plate pulverized coal burner diffuses radially, pulverized coal mixture flow ejected from the nozzle body, characterized in that crossing the plasma collide with. An inner cylinder nozzle is provided inside the nozzle body concentrically with the nozzle body, and a cylindrical fuel conduction space is formed between the inner cylinder nozzle and the nozzle body, and pulverized coal mixing is performed via the fuel conduction space. A pulverized coal burner in which a secondary air adjusting device is provided so that a flow is jetted and surrounds the tip of the nozzle body, and secondary air is jetted from the periphery of the nozzle body through the secondary air adjusting device A plurality of plasma torches in the center of the inner cylinder nozzle, the plasma torches form a plasma so as to diffuse radially outwardly in front of the nozzle body, and are ejected from the nozzle body. A pulverized coal burner characterized in that a mixed flow of pulverized coal intersects with the plasma.

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