JP2009299977A - Burner for pulverized fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner for pulverized fuel for keeping stable flame even if the pulverized fuel has a small amount of volatile component. <P>SOLUTION: This burner includes a nozzle body 6 opened toward a furnace 1 and jetting the pulverized fuel with the primary air 14 for combustion as mixed flow, a secondary air flow channel 22 for combustion concentrically formed around the nozzle body, and a pulverized fuel concentrating means 12a for partially enriching a concentration of the pulverized fuel of the mixed flow, and the mixed flow is jetted from the nozzle body while the concentration of the pulverized fuel is partially rich. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pulverized fuel burner provided in a furnace that uses pulverized fuel such as pulverized coal as fuel.

  A furnace using fine powder as a fuel, for example, a furnace using coal as a fuel, pulverized coal is pulverized by a pulverized coal machine into pulverized coal, and the pulverized coal is mixed with primary air, and then pulverized together with primary air. Some are supplied to a charcoal burner and ejected from the pulverized coal burner to a furnace to float and burn the pulverized coal.

  In the mixed flow of primary air and pulverized coal, secondary air for combustion heated to a required temperature (for example, 250 ° C. to 300 ° C.) is supplied from the periphery of the mixed flow so as to wrap the mixed flow. The pulverized coal in the mixed stream is heated by radiant heat from the furnace, emits volatile matter and ignites, generating a flame.

  A conventional pulverized coal burner will be described with reference to FIG.

  In FIG. 3, 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-fired 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 10 disposed on the center line of the inner cylinder nozzle 9.

  The outer cylinder nozzle 8 and the inner cylinder nozzle 9 each have a circular cross-sectional shape, and a fuel in which the furnace 1 side end is opened in a hollow cylindrical space between the outer cylinder nozzle 8 and the inner cylinder nozzle 9. A conductive space 11 is formed.

  A primary air introduction pipe 12 communicates with the outer cylinder nozzle 8 in a tangential direction at a base portion (end portion on the side of the counter-fired furnace 1) of the outer cylinder nozzle 8, and the primary air introduction pipe 12 is a pulverized coal machine. (Not shown). The primary air 14 and the pulverized coal transported to the primary air 14 through the primary air introduction pipe 12 flow into the fuel conduction space 11 from a tangential direction, and swirl inside the fuel conduction space 11. It is ejected from the tip.

  Further, one end of a tertiary air introduction pipe 13 is opened at the base of the inner cylinder nozzle 9, and the other end of the tertiary air introduction pipe 13 is opened in the wind box 4 and is fed to the wind box 4. Combustion air is taken in and led to the inner nozzle 9 as auxiliary combustion air, that is, tertiary combustion air.

  The secondary air adjusting device 7 includes an auxiliary air adjusting mechanism 15 that houses the tip of the nozzle body 6 and a main air adjusting mechanism 16 that is provided concentrically outside the auxiliary air adjusting mechanism 15. .

  The auxiliary air adjustment mechanism 15 includes a first air guide duct 18 that is reduced in diameter toward the tip, and an air volume adjustment blade via a rotation shaft 21 that is provided at the base of the first air guide duct 18 at equal circumferential intervals. 19 is rotatably provided, the rotary shaft 21 is connected via a link mechanism (not shown), and the air volume adjusting blade 19 is synchronously rotatable via the link mechanism.

  The main air adjusting mechanism 16 includes a second air guide duct 22 that is reduced in diameter toward the tip, and an air volume adjusting blade 23 that is provided in the second air guide duct 22 at equal circumferential intervals. The air volume adjusting blade 23 is rotatably provided via a rotating shaft 24 and can be rotated synchronously via a link mechanism like the air volume adjusting blade 19.

  The tip of the second air guide duct 22 is continuous with the throat 3 and the tip of the first air guide duct 18 is in a position retracted from the inner wall surface of the furnace wall 2. The tip of the inner cylinder nozzle 9 is in a position further retracted from the tip of the first air guide duct 18.

  Briefly describing the combustion in the pulverized coal burner 5, the pulverized coal is supplied together with the primary air 14 to the base of the fuel conduction space 11 from the primary air introduction pipe 12. The primary air 14 flows toward the furnace 1 while swirling in the fuel conduction space 11, is contracted in the process of passing through the fuel conduction space 11, and is ejected from the tip of the outer cylinder nozzle 8. The Secondary air 26, which is auxiliary combustion air, is heated to a required temperature and supplied to the wind box 4, and the secondary air 26 is adjusted in air volume by the air volume adjusting blade 23, and the second air guide duct. 22 is ejected into the furnace 1 together with the primary air 14 and the pulverized coal.

  The pulverized coal is made uniform by swirling in the fuel conduction space 11 in the process of being ejected into the furnace 1, is heated by the secondary air 26, and further receives radiant heat from the furnace 1. Heated. By heating, the volatile matter is released from the pulverized coal, the volatile matter is ignited, and the flame is continuously maintained.

  A part of the secondary air 26 taken into the second air guide duct 22 is taken into the first air guide duct 18 through the air volume adjusting blade 19 and ejected as secondary auxiliary air. Is done. By adjusting the air volume of the air volume adjusting blade 23 and the air volume of the air volume adjusting blade 19, the state of the supply amount flow of the secondary air 26 is changed, and the combustion state of pulverized coal 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 13 and ejected from the inner cylinder nozzle 9. The combustion state of pulverized coal is adjusted by ejecting the tertiary air 27. Therefore, the combustion state of the pulverized coal is adjusted to be optimum by adjusting the secondary air 26 and the tertiary air 27.

  The oil burner 10 is used when igniting pulverized coal.

  For the conventional pulverized coal burner 5 described above, a pulverized coal such as a bituminous coal such as bituminous coal including a predetermined amount, for example, about 20% of volatile components, is used.

  However, in recent years, it has been demanded to use a worse fuel, for example, oil coke which is a residue after petroleum refining is used as the fuel. Oil coke has a low volatile component of about 10%, and in the conventional pulverized coal burner 5 described above, the temperature of the pulverized fuel when jetted from the pulverized coal burner 5 is low, and sufficient volatile components are not released and flame. There is a problem that cannot be maintained.

  For this reason, in order to maintain the ignitability, it is necessary to concentrate the concentration of pulverized coal when ejected from the pulverized coal burner 5 to ensure volatile components. If the amount of is reduced, the transport of pulverized coal will be affected, so it could not be reduced to a given amount or less, and there was a limit to concentrating the concentration of pulverized coal.

Japanese Patent Laid-Open No. 8-200168

JP-A-8-312917

  In view of such circumstances, the present invention provides a pulverized fuel burner capable of maintaining a stable flame even with a pulverized fuel with a small amount of volatile components.

  The present invention is directed to a nozzle body that opens toward the furnace and ejects pulverized fuel together with primary air for combustion as a mixed flow; a combustion secondary air flow path formed concentrically around the nozzle body; Pulverized fuel concentration means for partially concentrating the pulverized fuel concentration of the mixed flow, and the mixed flow is related to a pulverized fuel burner ejected from the nozzle body in a state where the pulverized fuel concentration is partially high It is.

  Further, the present invention relates to a pulverized fuel burner, wherein the pulverized fuel concentrating means is a vent portion provided in the middle of supplying the mixed flow.

  The present invention also relates to a pulverized fuel burner which is connected to the pulverized fuel concentrating means in the nozzle body and is provided with a pulverized coal concentration groove corresponding to a portion where the pulverized fuel concentration of the mixed flow is high.

  The present invention also provides a baffle plate that blocks a portion of the combustion secondary air flow path corresponding to a portion of the mixed flow where the pulverized fuel concentration is high, and the baffle secondary air flow path is provided by the baffle plate. The present invention relates to a pulverized fuel burner configured such that a non-circulating portion is formed in the non-circulating portion and the exhaust gas in the furnace is attracted to the non-circulating portion.

  The present invention also relates to a pulverized fuel burner provided with a baffle plate that blocks a predetermined range adjacent to the pulverized coal concentration groove of the combustion secondary air flow path.

  Furthermore, according to the present invention, the combustion secondary air flow path is provided with an air volume adjusting blade for imparting a swirling flow to the combustion secondary air, and the baffle plate is used for the combustion 2 with respect to a portion where the pulverized fuel concentration is high. The present invention relates to a pulverized fuel burner that is deviated by a predetermined amount in the direction opposite to the swirling direction of the next air.

  According to the present invention, a nozzle body that opens toward the furnace and ejects pulverized fuel as a mixed flow together with the combustion primary air, and a combustion secondary air flow path formed concentrically around the nozzle body. And a pulverized fuel concentration means for partially concentrating the pulverized fuel concentration in the mixed stream, and the mixed stream is ejected from the nozzle body in a state where the pulverized fuel concentration is partially concentrated. Even with a small amount of pulverized fuel, a volatile component necessary for ignition can be obtained at a portion where the pulverized fuel concentration is high, and a stable flame can be maintained.

  Further, according to the present invention, since the pulverized fuel concentrating means is a vent portion provided in the middle of supplying the mixed flow, the concentration of the pulverized fuel can be partially concentrated by the energy of the mixed flow, and the pulverized fuel concentration is separately performed. There is no need to provide means.

  Further, according to the present invention, the pulverized coal concentration groove is provided in the nozzle body so as to correspond to the portion where the pulverized fuel concentration of the mixed stream is high, so that the concentrated pulverized fuel is Diffusion in the process of passing through the nozzle body is prevented.

  Further, according to the present invention, there is provided a baffle plate that blocks a portion of the combustion secondary air flow path corresponding to a portion where the pulverized fuel concentration of the mixed flow is high, and the baffle plate is used for the secondary air for combustion. Since a non-circulating part is formed in the flow path, and the exhaust gas in the furnace is attracted to the non-circulating part, the concentrated pulverized fuel can be rapidly heated by the high-temperature furnace exhaust gas, and the maintenance of the flame is stable. .

  Further, according to the present invention, since the baffle plate for blocking the predetermined range adjacent to the pulverized coal concentration groove of the combustion secondary air flow path is provided, the concentrated pulverized fuel is heated by the high-temperature furnace exhaust gas, Rapid heating and stable flame maintenance.

  Furthermore, according to the present invention, the flow passage for the secondary air for combustion is provided with an air volume adjusting blade for imparting a swirling flow to the secondary air for combustion, and the baffle plate performs the combustion on the portion where the pulverized fuel concentration is high. Since a predetermined amount is shifted in the direction opposite to the swirling direction of the secondary air for the combustion, even when a swirling flow is given to the secondary air for combustion, the exhaust gas in the furnace is reliably brought into contact with the concentrated pulverized fuel. It has an excellent effect that the maintenance of the flame is stable.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 and FIG. 2 show an example in which the burner for pulverized fuel in which the present invention is implemented is implemented as a burner for pulverized coal. In FIG. A detailed description will be omitted.

  A throat 3 is provided on the furnace wall 2 of the furnace 1, a pulverized coal burner 5 is provided concentrically with the throat 3, and the pulverized coal burner 5 is accommodated in a 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 10 disposed on the center line of the inner cylinder nozzle 9.

  The outer cylinder nozzle 8 and the inner cylinder nozzle 9 each have a circular cross-sectional shape, and a fuel in which the furnace 1 side end is opened in a hollow cylindrical space between the outer cylinder nozzle 8 and the inner cylinder nozzle 9. A conductive space 11 is formed.

  A primary air introduction pipe 12 is curvedly communicated with a base end (end on the side of the counter-fired furnace 1) of the outer cylinder nozzle 8 via a vent portion 12a, and the shaft center of the outer cylinder nozzle 8 and the The axial center of the primary air introduction pipe 12 is continuous. Further, the inner diameter of the primary air introduction pipe 12 and the inner diameter of the outer cylinder nozzle 8 are the same diameter, or when they are different diameters, the diameter gradually changes so that there are no discontinuous portions.

  The vent portion 12a functions as pulverized coal concentrating means, and the bent radius of the vent portion 12a is a value such that the primary air 14 flowing through the primary air introduction pipe 12 is smooth and does not cause turbulence, for example, a shaft. The bending radius at the center is made equal to the diameter of the primary air introduction pipe 12.

  A pulverized coal concentration groove 28 is formed at the top of the primary air introduction pipe 12. The upstream end of the pulverized coal concentration groove 28 reaches the downstream portion of the vent portion 12 a, and the downstream end opens at the downstream end of the outer cylinder nozzle 8. In FIG. 2, the cross-sectional shape of the pulverized coal concentration groove 28 is a semicircular shape, but an arbitrary shape such as a rectangular shape or a trapezoidal shape can be selected.

  The second air guide duct 22 forms a ring-shaped secondary air outlet 29 around the outer cylinder nozzle 8, and a portion adjacent to the pulverized coal concentration groove 28 of the secondary air outlet 29 is a baffle plate. It is blocked by 31. The baffle plate 31 closes the secondary air outlet 29 at a predetermined angle with the pulverized coal concentration groove 28 as a center so that the secondary air 26 is not ejected at the portion of the pulverized coal concentration groove 28.

  The operation will be described below.

  Pulverized coal is sent out as a mixed flow together with the primary air 14 from a pulverized coal machine (not shown), and the mixed flow is supplied from the primary air introduction pipe 12 to the outer cylinder nozzle 8 through the vent portion 12a.

  The mixed flow is deflected and receives centrifugal force in the process of passing through the vent portion 12a. Of the mixed flow, the pulverized coal has a specific gravity greater than that of the primary air 14, so that the pulverized coal concentration on the outer peripheral side of the mixed flow is concentrated.

  The outer peripheral portion of the mixed flow flows into the pulverized coal concentration groove 28 in a state where the pulverized coal concentration is concentrated. The pulverized coal concentration groove 28 prevents the pulverized coal from diffusing while the mixed flow flows through the fuel conducting space 11 and maintains the concentrated state of the pulverized coal concentration at the top of the fuel conducting space 11. . Therefore, the mixed flow is ejected from the outer cylinder nozzle 8 in a state where the pulverized coal concentration at the top of the fuel conduction space 11 is concentrated.

  The secondary air 26, which is auxiliary combustion air, is heated to a required temperature and fed to the wind box 4, and the secondary air 26 is adjusted in air volume by the air volume adjusting blade 23 and given a swirling flow. Then, it is ejected from the secondary air ejection port 29 through the second air guide duct 22 and further ejected to the furnace 1 so as to wrap the mixed flow.

  On the other hand, since the baffle plate 31 blocks the ejection of the secondary air 26, a non-flowing portion is generated in the ejection flow of the secondary air 26 ejected from the secondary air ejection port 29, and the baffle plate 31. The furnace 1 side becomes negative pressure. For this reason, high-temperature furnace exhaust gas 32 is attracted to the non-circulating portion.

  As the flue gas 32 in the furnace is attracted to the non-circulating portion, the concentrated pulverized coal is heated in contact with the flue gas 32 immediately after jetting, and volatile matter is released from the pulverized coal. Ignite. When the pulverized coal in the concentrated portion is ignited, the other portions are ignited and the flame is continuously maintained.

  Thus, even a pulverized fuel with a small amount of volatile components ignites reliably and the flame is stably maintained.

  The position where the baffle plate 31 is provided may be changed in consideration of the influence of the swirling flow ejected from the secondary air ejection port 29. For example, assuming that the swirl flow is clockwise in FIG. 2, the position of the baffle plate 31 is shifted by a predetermined angle in the counterclockwise direction.

  Further, when the pulverized coal concentrated through the vent portion 12a does not diffuse greatly in the process of passing through the fuel conduction space 11, the pulverized coal concentration groove 28 can be omitted.

  In FIG. 1, since the primary air introduction pipe 12 is connected to the outer cylinder nozzle 8 from below, the pulverized coal concentration groove 28 and the baffle plate 31 are provided in the upper part, but when connected from the horizontal direction. Needless to say, is provided in a horizontal region on the outer peripheral side.

  Further, as a pulverized coal concentration means, a separate pipe is connected to the outer cylinder nozzle 8 so that a pulverized coal mixed flow having a concentration higher than that of the pipe is supplied into the fuel conduction space 11 or to the pulverized coal concentration groove 28. It may be.

  In addition, even if there is no attraction phenomenon of the in-furnace exhaust gas 32, the pulverized coal concentrated stream is heated by receiving radiant heat from the inside of the furnace, the volatile matter is released from the pulverized coal, and the volatile matter is ignited. The plate 31 can be omitted.

It is a schematic sectional drawing which shows the burner for pulverized coal which concerns on embodiment of this invention. It is A arrow directional view of FIG. It is a schematic sectional drawing which shows the conventional burner for pulverized coal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 3 Throat 5 Pulverized coal burner 7 Secondary air conditioner 8 Outer cylinder nozzle 9 Inner cylinder nozzle 11 Fuel conduction space 12 Primary air introduction pipe 12a Vent part 14 Primary air 26 Secondary air 28 Pulverized coal concentration groove 29 2 Next air outlet 31 Baffle plate 32 Furnace exhaust gas

Claims (6)

  A nozzle body that opens toward the furnace and injects pulverized fuel together with the combustion primary air as a mixed flow; a combustion secondary air flow path formed concentrically around the nozzle body; A pulverized fuel burner, comprising: a pulverized fuel concentration means for partially concentrating a pulverized fuel concentration, wherein the mixed flow is ejected from the nozzle body in a state where the pulverized fuel concentration is partially high.   2. The pulverized fuel burner according to claim 1, wherein the pulverized fuel concentrating means is a vent portion provided in the middle of supplying the mixed flow.   The burner for pulverized fuel according to claim 1 or 2, wherein a pulverized coal concentration groove is provided in the nozzle body so as to communicate with the pulverized fuel concentrating means and to correspond to a portion where the pulverized fuel concentration of the mixed stream is high.   A baffle plate is provided to block a portion of the combustion secondary air flow path corresponding to a portion of the mixed flow where the fine pulverized fuel concentration is high, and the baffle plate forms a non-flowing portion in the combustion secondary air flow path. The burner for pulverized fuel according to any one of claims 1 to 3, wherein the burner is formed and configured to attract the exhaust gas in the furnace to the non-circulating portion.   The pulverized fuel burner according to claim 3, further comprising a baffle plate that blocks a predetermined range adjacent to the pulverized coal concentration groove of the combustion secondary air flow path.   The combustion secondary air flow path is provided with an air volume adjusting blade for giving a swirling flow to the combustion secondary air, and the baffle plate is arranged in a swirling direction of the combustion secondary air with respect to a portion where the pulverized fuel concentration is high. The burner for fine fuel according to claim 4 or 5, wherein the burner is deviated by a predetermined amount in the opposite direction.

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