JP2010091244A - Pulverized coal burner and pulverized-coal-fired boiler having the pulverized coal burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverized coal burner that improves ignition and reduces NOx furthermore, and a pulverized-coal-fired boiler having the pulverized coal burner. <P>SOLUTION: In the pulverized coal firing burner including a plurality of burner nozzles positioned on a side surface of a furnace for jetting a mixed flow of pulverized coal and air to form a flame and a wind box carrying the burner nozzles, having therethrough a pulverized coal supply line for supplying the pulverized coal and carrier air and having a secondary air supply line around the pulverized coal supply line, the secondary air supply line is arranged in a spaced relation over and under the pulverized coal supply line for supplying a pulverized coal flow of the mixture of pulverized coal and carrier air, and an air flow faster than the pulverized coal flow is supplied to the secondary air supply line to form a circular vortex where the pulverized coal flow circulates as entraining a hot gas around the jet end of the pulverized coal supply line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a plurality of burner nozzles that form a flame by ejecting a mixed flow of pulverized coal and air provided on a side surface of a furnace, and a pulverized coal supply that includes the burner nozzle and supplies the pulverized coal and conveying air. The present invention relates to a pulverized coal burner including a wind box in which a passage is disposed and a secondary air supply path is formed around the pulverized coal supply path, and a pulverized coal burning boiler including the pulverized coal burner.

In pulverized coal fired boilers, there are particularly strong environmental protection requirements for NOx, SOx and soot emissions, and various measures have been taken in the past. These are mainly countermeasures in the direction of processing what has occurred, but for NOx, countermeasures for suppressing the occurrence itself are also taken.
As what suppresses generation | occurrence | production of NOx, there exists a thing shown by patent document 1 (Unexamined-Japanese-Patent No. 2005-24136), for example.

In Patent Document 1, a flame holding mechanism is provided at the tip of a fuel flow path into which a mixed fluid of a pulverized solid fuel and a carrier gas is introduced, and one or more combustion airs are provided outside the fuel flow path. In the combustion apparatus having a burner having a flow path, the burner is provided with a plurality of fuel flow paths in which the fuel flow path is divided into two or more flow paths in the radial direction. A technique is shown in which the mixed fluid is ejected at the highest speed from any one of the other fuel flow paths except the fuel flow path provided on the outermost side.
As a result, a relatively low-speed flow of fuel for flame holding that is necessary for generating a large amount of reducing substances is ejected at the fuel flow path outlet provided on the outermost side of the burner. Further, the mixed fluid passing through the inner side of the burner becomes a relatively high-speed flow at the outlet of the fuel flow path, and an attempt is made to secure a flow rate necessary for causing a large amount of reducing substances to reach the main flow of the burner flame in the combustion apparatus.

On the other hand, as a pulverized coal burner that suppresses generation of NOx, a burner shown in FIG. 11 is conventionally known. FIG. 11 is a longitudinal side view showing an example of a conventional pulverized coal burner. For example, in Patent Document 1, Patent Document 2 (Patent No. 3021305), Patent Document 3 (Patent No. 3686250) by the present applicant, and the like. Are listed.
The pulverized coal burner in FIG. 11 is provided on the outer periphery of the pulverized coal supply path 61 and the pulverized coal supply path 61 for supplying the pulverized coal mixture 64 in which the pulverized coal and the carrier air are mixed, and supplies the secondary air 65. A secondary air supply path 62 and a tertiary air supply path 63 that is provided on the outer periphery of the secondary air supply path and supplies the tertiary air 66 are provided. Further, nozzles 67, 68, and 69 for ejecting fluid toward the furnace 3 are formed at the front ends (furnace 3 side) of the respective supply paths.

A density separator 72 is provided in the pulverized coal supply path 61 and has a wide block shape in the width direction so as to be in contact with the inner wall of the pulverized coal supply path 61. The concentration separator 72 is used to provide concentration separation to the pulverized coal mixture 64 supplied to the pulverized coal nozzle 67 for stable ignition combustion, reduction of NOx generation amount, and the like.
Further, a rectifier 73 is provided downstream of the concentration separator 72, and a light mixture having a low pulverized coal concentration passes through the rectifier 73, and a concentrated mixture having a high pulverized coal concentration is passed through the outer periphery of the rectifier 73. It is arranged to pass through. In this way, the circulated vortex 70 is formed around the pulverized coal nozzle 67 to circulate the rich mixture while retaining the high temperature gas, and ignition is performed.

JP 2005-24136 A Japanese Patent No. 3031305 Japanese Patent No. 3686250

However, according to Patent Document 1, in the outermost fuel flow path of the burner, a low-velocity fuel is ejected to make the mixed fluid passing through the pulverized coal supply path located inside the burner a high-speed flow, and the ejection flow velocity is changed. However, when the flow rate of the mixed fluid containing pulverized coal is changed, there is a problem that a density separator, a rectifier, and the like provided in the pulverized coal supply path are worn. Furthermore, since the density separator, the rectifier, and the like are arranged to improve ignition, these ignition improving means must be used to obtain stable ignition.
Further, in the pulverized coal burner as shown in FIG. 11, although it is known that NOx is reduced by reducing the secondary air flowing above and below the pulverized coal mixture, secondary air that is also cooling air is used. If the pressure is excessively reduced, there is a problem that the tip of the pulverized coal nozzle, the wall surface of the supply path and the like are burned out, and it cannot be extremely reduced, and there is a limit to reducing NOx. Since the secondary air flowing above and below the pulverized coal mixture only needs to function as an ignition type, it is preferable to reduce it as much as possible in order to reduce NOx.

  Therefore, in view of the problems of the prior art, the present invention has an object to provide a pulverized coal burner that improves ignition and further reduces NOx and a pulverized coal burning boiler including the pulverized coal burner. .

In order to achieve the above object, the present invention provides a plurality of burner nozzles that form a flame by ejecting a mixed flow of pulverized coal and air provided on the side of a furnace, and the pulverized coal transported by the burner nozzles. In a pulverized coal burner comprising a pulverized coal supply path for supplying air and an air box in which a secondary air supply path is formed around the pulverized coal supply path,
A secondary air supply path is provided by providing a gap above and below a pulverized coal supply path for supplying a pulverized coal stream in which the pulverized coal and the carrier air are mixed, and the secondary air supply path is more than the pulverized coal stream. A high-speed air flow is supplied, and a circulating vortex is formed around the ejection end side of the pulverized coal supply passage to circulate the pulverized coal flow while retaining hot gas.

According to the present invention, the secondary air that flows up and down adjacent to the pulverized coal supply path for supplying the pulverized coal flow is abolished, and the gap through which the abolished secondary air flows is maintained and the pulverized powder is interposed. Since a secondary air supply path is newly provided on the outer periphery of the coal supply path to actively supply an air flow faster than the pulverized coal flow, it is formed around the ejection end side of the pulverized coal supply path. The circulating vortex is greatly formed. This large circulation vortex is an eddy current formed by pulverized coal retaining hot gas and serves as an ignition source. Therefore, the ignition range is broadened and the ignition is greatly improved, resulting in a region with insufficient air. Increases and NOx is reduced. In addition, the unburned content is reduced and the efficiency is improved.
Further, since the high-speed air flow is supplied with a gap, the ignition is improved by forming a large circulation vortex without blowing off the ignition.

In addition, a burner nozzle located at the tip of the pulverized coal supply passage is provided by tilting the burner nozzle located at the tip of the secondary air supply passage or changing the jet velocity of the high-speed air flow flowing through the secondary air supply passage. And the circulation vortex is formed.
In this way, the burner nozzle located at the tip of the pulverized coal supply passage is changed by tilting the burner nozzle located at the tip of the secondary air supply passage or changing the jet velocity of the high-speed air flow flowing through the secondary air supply passage. Since the angle adjustment of the pulverized coal flow can be performed without providing a burner, the burner nozzle (pulverized coal nozzle) located at the tip of the pulverized coal supply path can be eliminated. Therefore, even when the pulverized coal nozzle is in a high temperature state that burns out, the pulverized coal nozzle can be removed and operated, and a large circulation vortex can be formed to achieve low NOx.

Furthermore, a refractory material is interposed in the gap between the pulverized coal supply path and the secondary air supply path.
Thus, by interposing a refractory material in the gap between the pulverized coal supply path and the secondary air supply path, the secondary air that flows up and down adjacent to the pulverized coal supply path without burning the pulverized coal supply path or the gap. Can be abolished.

Further, the present invention is characterized in that a plurality of holes for communicating minute air are formed in the cross section in the flow direction of the gap between the pulverized coal supply path and the secondary air supply path, and the minute air flow is supplied to the gap.
In this way, by introducing a minute amount of air that passes through the hole into the gap between the pulverized coal supply path and the secondary air supply path, there is no gap between the pulverized coal supply path and the pulverized coal supply path. The amount of secondary air flowing through the air can be reduced.

In addition, an opening that opens in a gap between the secondary air supply path and the pulverized coal supply path is provided on the upstream side of the secondary air supply path, and the secondary air supply path is located on the upstream side of the opening. Rectifying means is provided for rectifying so that a high-speed air flow flowing in the interior does not leak from the opening and is directed toward the ejection end of the secondary air supply path.
In this way, by providing the opening on the upstream side of the secondary air supply path, the ejector effect is generated by the high-speed air flow flowing in the secondary air supply path, and the gap between the pulverized coal supply path and the secondary air supply path Gas is sucked into the secondary air supply path. As a result, the circulation flow formed around the pulverized coal supply path is strengthened and the ignition is stabilized, and the flame is covered with the combustion gas, whereby the O ₂ concentration is reduced and the generation of NOx can be suppressed.

In addition, a negative pressure generating pipe disposed through the gap between the pulverized coal supply path and the secondary air supply path into the pulverized coal supply path, and one end of the negative pressure generation pipe is It opens to the gap | interval of a pulverized coal supply path and a secondary air supply path, and the other edge part is opening to the ejection end of the said pulverized coal supply path, It is characterized by the above-mentioned.
According to this configuration, the opening on the pulverized coal supply path ejection end side of the negative pressure generating pipe has a negative pressure because a pulverized coal flow is ejected around the opening, so the pulverized coal supply path and the secondary air supply path Gas is sucked from the opening in the gap. As a result, the circulation flow formed around the pulverized coal supply path is strengthened and the ignition is stabilized, and the flame is covered with the combustion gas, whereby the O ₂ concentration is reduced and the generation of NOx can be suppressed. Furthermore, the gas sucked from the opening in the gap between the pulverized coal supply path and the secondary air supply path is ejected from the opening on the pulverized coal supply path ejection end side through the negative pressure generating pipe, so it exists in the gas. NOx to be mixed is again mixed and reduced in the pulverized coal flow, and NOx can be reduced.

Further, a combustion auxiliary air supply path for supplying combustion auxiliary air is provided in the vicinity of the secondary air supply path and on the opposite side of the pulverized coal supply path, and at the tip of the combustion auxiliary air supply path, A combustion auxiliary air nozzle inclined toward the air supply path is provided.
According to this structure, the combustion auxiliary air ejected from the combustion auxiliary air nozzle is ejected in a diagonally downward direction due to the inclination of the nozzle, and the combustion auxiliary air is easily supplied to the flame, so that combustion can be promoted.

Furthermore, a vertical guide plate that divides combustion auxiliary air ejected from the combustion auxiliary air nozzle into a central straight traveling direction and a left-right diagonal direction is provided at least on the front end side of the combustion auxiliary air nozzle.
Of the combustion auxiliary air branched by the vertical guide plate, the air that is jetted in the straight direction in the center (and the downward slanting direction due to the nozzle inclination) is at a certain distance so as not to impair the ignition maintaining function of the high-speed air. It is mixed with air and quickly mixed and diffused into the pulverized coal stream while maintaining the speed in the flame direction to promote combustion. On the other hand, the air ejected in the left-right oblique direction (and the downward oblique direction due to the nozzle inclination) approaches the flame without being affected by the high-speed air ejected from the high-speed air supply path, and is then ejected from the pulverized coal supply path. It is attracted to the pulverized coal flow and quickly flows into the left and right parts of the pulverized coal flow, contributing to combustion. Therefore, combustion can be promoted by these branched combustion auxiliary air.

Furthermore, a lateral guide plate for guiding combustion auxiliary air ejected from the combustion auxiliary air nozzle in an obliquely downward direction is provided on at least the tip side of the combustion auxiliary air nozzle.
Thus, in addition to inclining the combustion auxiliary air nozzle, by providing the horizontal guide plate, it becomes possible to reliably inject the combustion auxiliary air in an obliquely downward direction.

Moreover, it is preferable that the pulverized coal burning boiler of this invention is a pulverized coal burning boiler provided with the above-mentioned pulverized coal burner.
That is, a furnace, a plurality of burner nozzles that form a flame by ejecting a mixed flow of pulverized coal and air provided on a side surface of the furnace, and the pulverized coal that includes the burner nozzle and supplies the pulverized coal and carrier air In a pulverized coal burning boiler comprising a supply path, a pulverized coal combustion burner comprising a wind box in which a secondary air supply path is formed around the pulverized coal supply path,
A secondary air supply path is provided by providing a gap above and below a pulverized coal supply path for supplying a pulverized coal stream in which the pulverized coal and the carrier air are mixed, and the secondary air supply path is more than the pulverized coal stream. A pulverized coal burner for supplying a high-speed air flow and forming a circulating vortex in which the pulverized coal flow stays and circulates by storing hot gas around the ejection end side of the pulverized coal supply path is provided. .
Thereby, while improving ignition, it is possible to provide the pulverized coal burning boiler provided with this pulverized coal burner which implement | achieves further NOx reduction.

As described above, according to the present invention, the secondary air flowing up and down adjacent to the pulverized coal supply path for supplying the pulverized coal flow is abolished, and the gap through which the abolished secondary air flows is maintained and the gap is reduced. Since a secondary air supply path is disposed on the outer periphery of the pulverized coal supply path to actively supply an air flow at a higher speed than the pulverized coal flow, the periphery of the ejection end side of the pulverized coal supply path The circulatory vortex that is formed is formed large. Therefore, the ignition range is expanded as compared with the conventional case, and the ignition is remarkably improved, and the area of air shortage is increased and NOx is reduced. In addition, the unburned content is reduced and the efficiency is improved.
Further, the burner nozzle located at the tip of the pulverized coal supply passage is changed by tilting the burner nozzle located at the tip of the secondary air supply passage or changing the jet velocity of the high-speed air flow flowing through the secondary air supply passage. Since the angle adjustment of the pulverized coal flow can be performed without providing the charcoal nozzle), the operation can be performed even if the pulverized coal nozzle is removed, and the NOx can be reduced by forming a large circulation vortex.
Furthermore, by interposing a refractory material in the gap between the pulverized coal supply path and the secondary air supply path, or by allowing minute air to flow in, the pulverized coal supply path and the gap between the pulverized coal supply path are not burned. The flowing secondary air can be reduced.
Furthermore, the circulation flow formed around the pulverized coal supply path is strengthened by the configuration in which the opening is provided upstream of the secondary air supply path or the structure in which the negative pressure generating pipe is provided in the pulverized coal supply path. Thus, the ignition is stabilized, and the flame is covered with the combustion gas, so that the O ₂ concentration is reduced and the generation of NOx can be suppressed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Only.
FIG. 1 is a block diagram showing an overall schematic configuration of a boiler according to an embodiment of the present invention, FIG. 2 is a front view showing an overall arrangement of (a) a pulverized coal burner according to an embodiment of the present invention, and (b) a burner. 3 is a longitudinal side view showing the pulverized coal burner according to the first embodiment, FIG. 4 is a longitudinal side view showing the pulverized coal burner according to the second embodiment, and FIG. 5 is a pulverized coal burner according to the third embodiment. 6 is a longitudinal side view showing a pulverized coal burner according to Embodiment 4, FIG. 7 is a longitudinal side view showing a pulverized coal burner according to Embodiment 5, and FIG. FIG. 9 is a longitudinal side view showing a pulverized coal burner according to Embodiment 6, and FIG. 10 is a front view of (a) the pulverized coal burner according to Embodiment 6, and (b) a sectional view taken along the line BB.

First, the pulverized coal fired boiler according to Embodiments 1 to 5 of the present invention to be described later will be described with reference to FIG.
FIG. 1 is a block diagram showing an overall schematic configuration of a boiler according to an embodiment of the present invention. In the boiler 1, a furnace 3 installed in a vertical direction and a furnace wall 5 of the furnace 3 are installed below. Combustion device 7, flue 9 connected to the outlet of furnace 3, superheater 11, reheater 13 and economizer 15 provided from upper part of furnace 3 to flue 9, and upper part of furnace 3 A provided steam drum 17 is provided.

  A large number of water pipes (not shown) extend in the vertical direction inside the furnace wall 5. Each water pipe is connected to the steam drum 17 at upper and lower ends. The combustion device 7 includes a plurality of pulverized coal burners 10 (see FIG. 3) attached to the lower part of the furnace wall 5, an additional air nozzle 20 attached in the vicinity of the outlet of the furnace 5, and pulverized coal to the pulverized coal burner 10. A pulverized coal supply means 21 for supplying, a high temperature gas supply means 23 for supplying high temperature gas to the pulverized coal burner 10, and an air supply means 25 for supplying combustion air to the pulverized coal burner 10 and the additional air nozzle 20 are provided. ing.

The pulverized coal supply means 21 includes a pulverized coal machine 27 that pulverizes coal supplied through a coal feeder and a meter (not shown) to a size suitable for combustion (for example, several μm to several hundred μm), and pulverized coal. The pulverized coal generated by the machine 27 is provided with a coal supply pipe 29 for conveying the pulverized coal to the pulverized coal burner 10 as a pulverized coal mixture by pressurized conveying air supplied from an air source (not shown).
The carrier air is set so that the outlet temperature of the pulverized coal machine 27 is about 80 ° C. from the safety aspect of the pulverized coal machine 27.

The air supply means 25 pressurizes and supplies a pressurized air blower (not shown), a wind box 31 provided on the outer wall of the furnace 3, and air for connecting the forced air blower to the wind box 31 and the additional air nozzle 20. A tube 33 is provided.
The combustion auxiliary air (tertiary air) passing through the air pipe 33 is heat-exchanged with, for example, about 360 ° C. combustion exhaust gas passing through the flue 9 by the rotary regenerative heat exchanger 35 and heated to 300 to 350 ° C. It is supplied to the wind box 31.
The hot gas supply means 23 is provided with an exhaust gas pipe 37 that connects the flue 9 and the pulverized coal burner 10. The exhaust gas pipe 37 is connected to the flue 9 position where, for example, the temperature of the combustion exhaust gas is 800 ° C. and the oxygen content is 4% or less during rated operation.

Further, in one embodiment of the present invention, as shown in FIG. 2A, a plurality of burners are combined in the vertical direction and used as an integrated type continuous in the furnace height direction. That is, the duct of combustion auxiliary air supplied to the pulverized coal flame and the burner wind box 31 are integrated into a continuous type in the vertical direction. Further, as shown in FIG. 2 (b), the pulverized coal supply path for supplying the mixture of pulverized coal and carrier air into the furnace is branched into a plurality of pipes having different pulverized coal concentrations, and the mixture is supplied into the furnace. To erupt.
Although FIG. 2 shows an integrated type in which the burner wind box is continuous in the vertical direction, in the embodiment of the present invention, the burner wind box is divided into a plurality of unit wind boxes in the vertical direction. A shape divided into pieces is also preferably used.

(Embodiment 1)
The pulverized coal burner according to Embodiment 1 will be described with reference to FIG.
The pulverized coal burner 10 in FIG. 3 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the high speed air (secondary air). ) A secondary air supply passage 14 that supplies 19 and a combustion auxiliary air that is provided on the opposite side of the pulverized coal supply passage 12 in the vicinity of the secondary air supply passage 14 and supplies combustion auxiliary air (tertiary air) 22. A supply path 16 is provided. The high-speed air 19 is faster than the pulverized coal mixture 18 and the combustion auxiliary air 22. For example, the flow rate of the pulverized coal mixture 18 is 25 m / s, but is 80 to 150 m / s.
In addition, a gap is formed between the pulverized coal supply path 12 and the secondary air supply path 14, and a refractory material 24 is provided in this gap. This gap maintains the space of the secondary air supply path 62 shown in FIG. An example of the refractory material is castable.

A pulverized coal nozzle 26 that ejects fluid toward the furnace 3 is provided at the tip (furnace 3 side) of the pulverized coal supply path 12. Similarly, high-speed air nozzles 28 and combustion auxiliary air nozzles 32 are provided at the tips of the secondary air supply path 14 and the combustion auxiliary air supply path 16. Each of these nozzles can be tilted up and down to adjust the angle of the jet.
Reference numeral 34 denotes a wear prevention member provided at a bent portion of the pulverized coal supply path 12, and prevents wear due to the pulverized coal contained in the pulverized coal mixture 18. The wear preventing member 34 has a block shape or a plate shape, and is formed at a bent portion or a narrow portion of the pipe.

In the pulverized coal burner 10 in FIG. 3, the pulverized coal mixture 18 supplied to the pulverized coal supply path 12 is actively supplied with the high-speed air 19 with a gap above and below, so that the pulverized coal nozzle 26 A circulatory vortex 30 in which the pulverized coal mixture is circulated while retaining the high-temperature gas is formed large as shown in FIG. This circulating vortex 30 is formed large for positively supplying high-speed air in addition to eliminating secondary air flowing up and down adjacent to the conventional pulverized coal supply path.
Since the circulation vortex 30 serves as an ignition source, the ignition is remarkably improved, the air shortage region is increased, and NOx is reduced. In addition, the unburned content is reduced and the efficiency is improved.

(Embodiment 2)
Next, the pulverized coal burner according to Embodiment 2 will be described with reference to FIG. In the following embodiment, the same reference numerals are given to the same components as those in the first embodiment shown in FIG.
As in the first embodiment, the pulverized coal burner 10 in FIG. 4 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the pulverized coal supply path 12. A secondary air supply path 14 that supplies high-speed air 19 and a combustion auxiliary that is provided on the opposite side of the pulverized coal supply path 12 in the vicinity of the secondary air supply path 14 and supplies combustion auxiliary air (tertiary air) 22. An air supply path 16 is provided.
In addition, a gap is formed between the pulverized coal supply path 12 and the secondary air supply path 14, and a plurality of holes 36 are formed in the gap in the flow direction to communicate minute air. Stream 37 is fed. This gap maintains the space of the secondary air supply path 62 shown in FIG. In addition, as what forms a some hole, the thing by punching metal is mentioned, for example.

A pulverized coal nozzle 26 that ejects fluid toward the furnace 3 is provided at the tip (furnace 3 side) of the pulverized coal supply path 12. Similarly, high-speed air nozzles 28 and combustion auxiliary air nozzles 32 are provided at the tips of the secondary air supply path 14 and the combustion auxiliary air supply path 16. Each of these nozzles can be tilted up and down to adjust the angle of the jet.
Reference numeral 34 denotes a wear prevention member provided at a bent portion of the pulverized coal supply path 12, and prevents wear due to the pulverized coal contained in the pulverized coal mixture 18.

In the pulverized coal burner 10 in FIG. 4, as in the first embodiment, the pulverized coal mixture 18 supplied to the pulverized coal supply path 12 is positively supplied with high-speed air 19 with a gap above and below it. Therefore, a large circulating vortex 30 is formed around the pulverized coal nozzle 26 in which the pulverized coal mixture circulates while retaining the high-temperature gas.
Therefore, since this circulation vortex 30 becomes an ignition source, ignition is remarkably improved, an air shortage region is increased, and NOx is reduced. In addition, the unburned content is reduced and the efficiency is improved.

(Embodiment 3)
Next, the pulverized coal burner according to Embodiment 3 will be described with reference to FIG. In the following embodiment, the same reference numerals are given to the same components as those in the first embodiment shown in FIG.
As in the first embodiment, the pulverized coal burner 10 in FIG. 5 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the pulverized coal supply path 12. A secondary air supply path 14 that supplies high-speed air 19 and a combustion auxiliary that is provided on the opposite side of the pulverized coal supply path 12 in the vicinity of the secondary air supply path 14 and supplies combustion auxiliary air (tertiary air) 22. An air supply path 16 is provided.

  In addition, a gap is formed between the pulverized coal supply path 12 and the high-speed air supply path 14, and a refractory material 24 is provided in this gap. Although not shown, a plurality of holes for communicating minute air may be formed in the cross section in the flow direction of the gap in the same manner as in FIG. 4, and the minute air flow may be supplied to the gap.

Further, a high-speed air nozzle 28 and a combustion auxiliary air nozzle 32 are provided at the ends (furnace 3 side) of the secondary air supply path 14 and the combustion auxiliary air supply path 16. Each of these nozzles can be tilted up and down to adjust the angle of the jet.
Reference numeral 34 denotes a wear prevention member provided at a bent portion of the pulverized coal supply path 12, and prevents wear due to the pulverized coal contained in the pulverized coal mixture 18.

In FIG. 5, the pulverized coal nozzle 26 (see FIGS. 3 and 4) that ejects fluid toward the furnace 3 is not provided at the tip of the pulverized coal supply path 12. Different from charcoal burner.
The angle of the pulverized coal mixture 18 can be adjusted without providing the pulverized coal nozzle by tilting the high speed air nozzle 28 and the combustion auxiliary air nozzle 32 to adjust the angle of the jet flow of the high speed air 19 and the combustion auxiliary air 22. It can be carried out.
It is also effective to change the jet flow velocity of the jet flow of the high-speed air 19 and the combustion auxiliary air 22 as means for adjusting the angle of the pulverized coal mixture 18.

Thereby, the pulverized coal burner 10 can be operated by removing the pulverized coal nozzle, and the circulating vortex 30 in which the pulverized coal mixture 18 stays and circulates around the ejection end side of the pulverized coal supply path 12 while retaining the high temperature gas. Is formed large.
Therefore, also in the present embodiment, the ignition is remarkably improved, the air shortage region is increased, and NOx is reduced. In addition, the unburned content is reduced and the efficiency is improved.
Further, the pulverized coal nozzle is not required, the number of parts is reduced, and the cost can be reduced.

(Embodiment 4)
Next, the pulverized coal burner according to Embodiment 4 will be described with reference to FIG. In the following embodiment, the same reference numerals are given to the same components as those in the first embodiment shown in FIG.
As in the first embodiment, the pulverized coal burner 10 in FIG. 6 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the pulverized coal supply path 12. A secondary air supply path 14 that supplies high-speed air 19 and a combustion auxiliary that is provided on the opposite side of the pulverized coal supply path 12 in the vicinity of the secondary air supply path 14 and supplies combustion auxiliary air (tertiary air) 22. An air supply path 16 is provided.

  In addition, a gap is formed between the pulverized coal supply path 12 and the secondary air supply path 14. Although not shown, a refractory material may be provided in the gap in the same manner as in FIG. 3, or a plurality of holes for communicating minute air in the cross section in the flow direction of the gap are formed in the same manner as in FIG. A stream may be supplied.

The lengths of the pulverized coal supply path 12, the secondary air supply path 14, and the combustion auxiliary air supply path 16 are not particularly limited, but in FIG. 6, the pulverized coal is smaller than the secondary air supply path 14 and the combustion auxiliary air supply path 16. The supply path 12 is shortened. Thereby, the circulation vortex 30 is easily formed around the pulverized coal supply path 12.
Although not shown, as in FIGS. 3 to 5, the pulverized coal nozzle 26, the high-speed air nozzle 28, and the combustion auxiliary are provided at the tips of the pulverized coal supply path 12, the secondary air supply path 14, and the combustion auxiliary air supply path 16. An air nozzle 32 may be provided. Further, although not shown, the wear preventing member 34 may be provided at the bent portion of the pulverized coal supply path 12 as in FIGS. 3 to 5.

Furthermore, in the fourth embodiment, an opening 40 that opens in the gap between the pulverized coal supply path 12 and the secondary air supply path 14 is provided on the upstream side of the secondary air supply path 14. The opening 40 is preferably provided in a slit shape in the width direction of the secondary air supply path 14.
Further, on the upstream side of the opening 40, a rectifying plate 41 that rectifies the high-speed airflow flowing in the secondary air supply path 14 so as not to leak from the opening 40 and toward the ejection end of the secondary air supply path 14. Is provided. The rectifying plate 41 has an edge on one side attached to the upstream side of the opening 40 and an edge on the other side located on the ejection end side so as to be inclined inward with respect to the secondary air supply path 14. Is done. Preferably, the current plate 41 is disposed so as to cover at least a part of the opening 40.
A plurality of openings 40 may be provided in the high-speed air flow direction of the secondary air supply path 14.

Thus, by providing the opening 40 on the upstream side of the secondary air supply path 14, the ejector effect is generated by the high-speed air flow flowing in the secondary air supply path 14, and the pulverized coal supply path 12 and the secondary air are generated. The gas in the gap of the supply path 14 is sucked into the secondary air supply path 14. As a result, the circulation flow 30 formed around the pulverized coal supply path 12 is strengthened and ignition is stabilized, and the O ₂ concentration is reduced by covering the flame with the combustion gas, thereby suppressing the generation of NOx. it can.

(Embodiment 5)
Next, a pulverized coal burner according to Embodiment 5 will be described with reference to FIGS. In the following embodiment, the same reference numerals are given to the same components as those in the first embodiment shown in FIG.
As in the first embodiment, the pulverized coal burner 10 in FIG. 7 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the pulverized coal supply path 12. A secondary air supply path 14 that supplies high-speed air 19 and a combustion auxiliary that is provided on the opposite side of the pulverized coal supply path 12 in the vicinity of the secondary air supply path 14 and supplies combustion auxiliary air (tertiary air) 22. An air supply path 16 is provided.

In addition, a gap is formed between the pulverized coal supply path 12 and the secondary air supply path 14. Although not shown, a refractory material may be provided in the gap in the same manner as in FIG. 3, or a plurality of holes for communicating minute air in the cross section in the flow direction of the gap are formed in the same manner as in FIG. A stream may be supplied.
Although not shown, as in FIGS. 3 to 5, the pulverized coal nozzle 26, the high-speed air nozzle 28, and the combustion auxiliary are provided at the tips of the pulverized coal supply path 12, the secondary air supply path 14, and the combustion auxiliary air supply path 16. An air nozzle 32 may be provided. Further, although not shown, the wear preventing member 34 may be provided at the bent portion of the pulverized coal supply path 12 as in FIGS. 3 to 5.

  Further, in the fifth embodiment, a negative pressure generating pipe 42 is provided that is provided through the gap between the pulverized coal supply path 12 and the secondary air supply path 14 into the pulverized coal supply path 12. The negative pressure generating pipe 42 has an opening 43 having one end opened in the gap between the pulverized coal supply path 12 and the secondary air supply path 14, and the other end located in the pulverized coal supply path 12. An opening 44 is formed at the ejection end of the pulverized coal supply path 12. The opening 43 opened in the gap is formed toward the furnace 3 side. The openings 43 are provided symmetrically above and below the pulverized coal supply path 12. A pipe 45 extending into the pulverized coal supply path 12 from the opening 44 on the ejection end side branches up and down, and the branched pipe 46 penetrates the pulverized coal supply path 12 so as to pass through the upper pulverized coal supply path 12. Projecting into the gap between the secondary air supply path 14 and the gap between the lower pulverized coal supply path 12 and the secondary air supply path 14, and connected to the openings 43, 43.

FIG. 8 is a view taken in the direction of arrow A in FIG. The opening 43 on the gap side is formed in a slit shape in the width direction of the pulverized coal supply path 12. This is because the gas in the gap is sucked evenly.
The pipe 46 extending in the vertical direction is formed narrower than the width of the openings 43 and 44 so as not to hinder the flow of the pulverized coal flow in the pulverized coal supply path 12, and the pulverized coal in the pulverized coal supply path 12. It is preferable to secure a sufficient flow path area.

By providing the above configuration, the opening 44 on the pulverized coal supply path ejection end side of the negative pressure generating pipe 42 becomes negative pressure because the pulverized coal flow is ejected to the periphery, so that the pulverized coal supply path 12 and the secondary The gas is sucked from the opening 43 in the gap of the air supply path 14. As a result, the circulation flow 30 formed around the pulverized coal supply path 12 is strengthened and ignition is stabilized, and the O ₂ concentration is reduced by covering the flame with the combustion gas, thereby suppressing the generation of NOx. it can. Further, the gas sucked from the opening 43 in the gap between the pulverized coal supply path 12 and the secondary air supply path 14 is ejected from the opening 44 on the pulverized coal supply path ejection end side through the negative pressure generating pipe 42. NOx present in the gas is mixed again in the pulverized coal flow and reduced, and NOx can be reduced.

(Embodiment 6)
Next, a pulverized coal burner according to Embodiment 6 will be described with reference to FIGS. In the following embodiment, the same reference numerals are given to the same components as those in the first embodiment shown in FIG.
Embodiment 6 described below can be used in combination with the configurations of Embodiments 1 to 5 described above.
As in the first embodiment, the pulverized coal burner 10 in FIG. 9 is provided on the outer periphery of the pulverized coal supply path 12 for supplying the pulverized coal mixture 18 in which the pulverized coal and the carrier air are mixed, and the pulverized coal supply path 12. A secondary air supply passage 14 for supplying high-speed air (secondary air) 19 and a combustion auxiliary air (tertiary air) 22 provided on the opposite side of the pulverized coal supply passage 12 in the vicinity of the secondary air supply passage 14. And a combustion auxiliary air supply passage 16 for supplying the air.

In addition, a gap is formed between the pulverized coal supply path 12 and the secondary air supply path 14, and a refractory material 24 is provided therebetween. Further, although not shown, the wear preventing member 34 may be provided at the bent portion of the pulverized coal supply path 12 as in FIGS. 3 to 5.
The tip of the pulverized coal supply path 12 and the secondary air supply path 14 may employ either a configuration in which a nozzle is provided or a configuration in which no nozzle is provided. 9 and 10, as an example, a configuration in which a high-speed air nozzle 28 is provided in the secondary air supply path 14 is employed.

A combustion auxiliary air nozzle 32 is provided at the tip of the combustion auxiliary air supply path 16. The combustion auxiliary air nozzle 32 is disposed such that the tip of the nozzle is inclined toward the high-speed air nozzle 28 side so that the ejection direction of the combustion auxiliary air 22 is on the flame side.
Further, as shown in FIG. 10, longitudinal guide plates 53 and 53 that divide the combustion auxiliary air 22 into the central straight traveling direction and the left and right diagonal directions are provided at least on the tip side of the combustion auxiliary air nozzle 32. At least two vertical guide plates 53 are provided in the combustion auxiliary air nozzle 32. By this vertical guide plate 53, the combustion auxiliary air supply passage 16 is branched into a central branch passage 16a and left and right branch passages 16b and 16b on both sides thereof. The vertical guide plate 53 is disposed so that the nozzle front end side of the central branch passage 16a is expanded. At this time, a branch plate 52 may also be provided on the combustion auxiliary air supply path 16 so as to extend from the vertical guide plate 53, and this is provided in parallel with the combustion auxiliary air supply path 16.
Furthermore, as shown in FIGS. 9 and 10 (a), a lateral guide plate 51 may be provided in the combustion auxiliary air nozzle 32 for guiding the combustion auxiliary air 22 to be ejected to the flame side. The horizontal guide plate 51 is provided horizontally in the combustion auxiliary air nozzle 32, and the nozzle tip side is inclined to the high-speed air nozzle 28 side. When the horizontal guide plate 51 is provided, the vertical guide plate 53 is installed in two upper and lower stages.

By providing the above configuration, the air passing through the central branch passage 16 a in the combustion auxiliary air 22 is jetted straight in a diagonally downward direction by the inclination of the nozzle 32 and the lateral guide plate 51 and mixed with the high-speed air 19. . The combustion auxiliary air 22 is mixed with the high-speed air 19 at a certain distance so as not to impair the ignition maintaining function of the high-speed air 19, and is quickly mixed and diffused into the pulverized coal flow while maintaining the speed in the flame direction. , Promote combustion.
On the other hand, the air passing through the left and right branch passages 16 b, 16 b in the combustion auxiliary air 22 is jetted in a downward diagonal direction by the inclination of the nozzle 32 and the horizontal guide plate 51 and in a diagonal direction by the vertical guide plate 51. The combustion auxiliary air 22 ejected in the downward oblique direction and the laterally oblique direction approaches the flame without being affected by the high-speed air 19 ejected from the high-speed air nozzle 14, and then the pulverized coal ejected from the pulverized coal burner 10. It is drawn to the flow and quickly flows into the left and right parts of the pulverized coal flow, contributing to combustion. The left and right branch passages 16b and 16b are reduced in diameter by the vertical guide plate 51 on the ejection portion side, so that the ejection speed is increased and the pulverized coal flow can be reliably reached.

  As described above, the combustion auxiliary air 22 ejected from the combustion auxiliary air nozzle 32 is configured to be ejected in an obliquely downward direction by the inclination of the nozzle 32 and the lateral guide plate 51, whereby the combustion auxiliary air 22 is generated in the flame. It is easy to be supplied, and it branches into air that is jetted straight by the vertical guide plate 53 and air that is jetted in an oblique direction, so that the jetted air is mixed with the high-speed air 19 and ignited. The air jetted obliquely in the left and right directions bypasses the high-speed air 19 and flows from the left and right sides of the pulverized coal flow to contribute to combustion, and the combustion can be promoted by the respective air.

  Finally, the pulverized coal burner in the above-described embodiment of the present invention will be described with reference to FIG. The gaps provided above and below the pulverized coal supply path maintain the space of the secondary air supply path 62 shown in FIG. 11, but the width of the gap (reference S) is the width of the pulverized coal supply path. When (reference sign B) is 1, it is also possible to expand to 0.5-2. This is also a value at which the circulation vortex does not become too small and the unburned content does not increase.

  Moreover, the high-speed air supply path 14 and the secondary air supply path 16 shown in FIGS. 3-7 utilize the space of the tertiary air supply path 63 arrange | positioned at the outer periphery of the secondary air supply path shown in FIG. Since it can be formed, the pulverized coal burner can be made compact. In addition, since the flow velocity of the present invention is generally higher than the flow velocity of the tertiary air supplied to the conventional tertiary air supply passage, the air mixing diffusion is improved, the flame length near the burner is shortened, and the air shortage is reduced. The area can be increased to further reduce NOx.

  Further, in the present invention, a concentration separator, a rectifier, a flame holder, and a ceramic etc. that prevent wear of the wall due to pulverized coal brought to the outside of the pipe by the concentration separator, which has been conventionally provided for improving ignition, are provided. Since only a minimum flow rate balance adjustment is possible, cost reduction and wear troubles can be prevented.

  According to the present invention, the ignition is improved and further NOx reduction is realized, which is advantageous when applied to a pulverized coal burner and a pulverized coal burning boiler equipped with the pulverized coal burner.

1 is a block diagram showing an overall schematic configuration of a boiler according to an embodiment of the present invention. It is the front view which shows the whole arrangement | positioning of (a) pulverized coal burner which concerns on one Embodiment of this invention, (b) The burner front-end | tip part side view. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 1. FIG. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 2. FIG. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 3. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 4. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 5. It is A arrow directional view of FIG. It is a vertical side view which shows the pulverized coal burner which concerns on Embodiment 6. It is a front view of (a) pulverized coal burner concerning Embodiment 6, and (b) is a BB line sectional view. It is a vertical side view which shows the conventional pulverized coal burner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler 3 Furnace 10 Pulverized coal burner 12 Pulverized coal supply path 14 Secondary air supply path 16 Combustion auxiliary air supply path 18 Pulverized coal mixture 19 High-speed air 22 Combustion auxiliary air (tertiary air)
26 Pulverized coal nozzle 30 Circulating vortex

Claims (10)

A plurality of burner nozzles that form a flame by jetting a mixed flow of pulverized coal and air provided on the side of the furnace, and a pulverized coal supply passage that includes the burner nozzle and that supplies the pulverized coal and conveying air pass therethrough. In a pulverized coal burner comprising a wind box in which a secondary air supply path is formed around the pulverized coal supply path,
A secondary air supply path is provided by providing a gap above and below a pulverized coal supply path for supplying a pulverized coal stream in which the pulverized coal and the carrier air are mixed, and the secondary air supply path is more than the pulverized coal stream. A pulverized coal burner, characterized in that a high-speed air flow is supplied, and a circulating vortex is formed around the jet end side of the pulverized coal supply passage to circulate the pulverized coal flow while retaining hot gas.   The burner nozzle located at the tip of the secondary air supply passage is tilted or the flow velocity of the high-speed air flow flowing through the secondary air supply passage is changed, and the burner nozzle located at the tip of the pulverized coal supply passage is not provided. The pulverized coal burner according to claim 1, wherein a circulating vortex is formed.   The pulverized coal burner according to claim 1 or 2, wherein a refractory material is interposed in a gap between the pulverized coal supply path and the secondary air supply path.   3. A plurality of holes for communicating minute air are formed in a cross section in the flow direction of a gap between the pulverized coal supply path and the secondary air supply path, and a minute air flow is supplied to the gap. The pulverized coal burner described.   An opening that opens in the gap between the secondary air supply path and the pulverized coal supply path is provided on the upstream side of the secondary air supply path, and the interior of the secondary air supply path is located upstream of the opening. The pulverized coal burner according to claim 1 or 2, further comprising a rectifying means for rectifying the flowing high-speed air flow so as not to leak from the opening and toward the ejection end of the secondary air supply path.   A negative pressure generating pipe disposed through the gap between the pulverized coal supply path and the secondary air supply path into the pulverized coal supply path, and one end of the negative pressure generation pipe is the pulverized coal 3. The pulverized coal burner according to claim 1, wherein the pulverized coal burner is opened in a gap between the supply passage and the secondary air supply passage, and the other end portion is opened at an ejection end of the pulverized coal supply passage.   A combustion auxiliary air supply path for supplying combustion auxiliary air is provided on the opposite side of the pulverized coal supply path in the vicinity of the secondary air supply path, and the secondary air supply is provided at the tip of the combustion auxiliary air supply path. The pulverized coal burner according to claim 1 or 2, further comprising a combustion auxiliary air nozzle inclined toward the road side.   8. A vertical guide plate that divides combustion auxiliary air ejected from the combustion auxiliary air nozzle into a central straight traveling direction and a left-right diagonal direction is provided at least on a front end side of the combustion auxiliary air nozzle. Pulverized coal burner.   The pulverized coal burner according to claim 7, wherein a lateral guide plate for guiding the combustion auxiliary air ejected from the combustion auxiliary air nozzle in a diagonally downward direction is provided on at least a tip side of the combustion auxiliary air nozzle. A furnace, a plurality of burner nozzles that form a flame by ejecting a mixed flow of pulverized coal and air provided on a side surface of the furnace, and a pulverized coal supply path that includes the burner nozzle and supplies the pulverized coal and carrier air In a pulverized coal burning boiler comprising a pulverized coal combustion burner comprising a wind box in which a secondary air supply path is formed around the pulverized coal supply path,
A secondary air supply path is provided by providing a gap above and below a pulverized coal supply path for supplying a pulverized coal stream in which the pulverized coal and the carrier air are mixed, and the secondary air supply path is more than the pulverized coal stream. A pulverized coal burner for supplying a high-speed air flow and forming a circulating vortex in which the pulverized coal flow stays and circulates by storing hot gas around the ejection end side of the pulverized coal supply path is provided. A pulverized coal fired boiler.

Images