JP2006057903A - Dust coal burner and boiler using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust coal burner capable of realizing further reduction of NOx. <P>SOLUTION: This dust coal burner 19 totally putting in an air amount smaller than a theoretical air amount of an inputted dust coal amount to perform combustion in reducing atmosphere has: a dust coal mixture passage leading dust coal mixture of dust coal and carrying air, and injecting it from the tip; a high temperature gas supply passage 67 provided such that the high temperature gas supply passage 67 covers at least a tip portion of the dust coal mixture passage, leading high temperature gas having high temperature effective in a volatile matter discharge of the dust coal, and low oxygen concentration, and injecting it into a furnace 3; and a tertiary air passage provided such that the tertiary air passage covers at least the tip periphery of the high temperature gas supply passage 67, supplying tertiary air into the furnace 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pulverized coal burner suitable for use in a pulverized coal burning boiler that generates steam for power generation or industrial use, and a boiler using the pulverized coal burner.

In these pulverized coal fired boilers, there is a strong demand for environmental conservation especially regarding emission of dust, SOx and NOx, and various measures have been taken conventionally. These are mainly countermeasures in the direction of processing what has occurred, but for NOx, countermeasures for suppressing the occurrence itself are also taken.
For example, Japanese Patent Application Laid-Open No. H10-133707 discloses an effective method for suppressing the generation of NOx.
This keeps the main combustion zone in a reducing atmosphere so that the amount of air input at the pulverized coal burner is less than the theoretical amount of pulverized coal input for combustion. As a result, the amount of NOx generated in the early stage of pulverized coal combustion is reduced and the amount of NOx discharged to the downstream is reduced. Thereafter, combustion air is supplied from an additional air nozzle provided downstream of the main combustion zone, and oxidation combustion is performed to complete the combustion.
And if the ratio of the combustion air thrown in from the additional air nozzle is increased and the reducing atmosphere in the main combustion zone is strengthened, the amount of NOx emission becomes smaller.

Japanese Patent Laid-Open No. 10-213309 (paragraphs [0001] to [0019] and FIG. 6)

By the way, in the thing of patent document 1, if the ratio of the combustion air thrown in from an additional air nozzle exceeds 30%, even if this ratio is increased, the amount of NOx emission will not be reduced any further, that is, the reduction of NOx. Has been found to have limitations.
Recently, further reduction in NOx has been demanded, and the one described in Patent Document 1 has a problem that it cannot sufficiently satisfy the request functionally.

  An object of this invention is to provide the pulverized coal burner which can implement | achieve further NOx reduction, and a boiler using the same in view of the said problem.

In order to solve the above problems, the present invention employs the following means.
That is, the pulverized coal burner according to the present invention is a pulverized coal burner in which an amount of air smaller than the theoretical amount of pulverized coal to be input is introduced as a whole and burned in a reducing atmosphere. A pulverized coal mixture supply passage that guides the air-fuel mixture and is ejected from the tip, and at least a tip portion of the pulverized coal mixture supply passage, is provided at a high temperature that is effective for releasing the volatile matter of the pulverized coal and low A high-temperature gas supply passage that guides a high-temperature gas having an oxygen concentration and ejects the high-temperature gas to the furnace, and an air supply passage that is provided so as to cover at least the outer periphery of the tip of the high-temperature gas supply passage and supplies combustion air to the furnace. It is characterized by that.

According to the present invention, since the high temperature gas supply passage is provided so as to cover the tip portion of the pulverized coal mixture supply passage, the pulverized coal mixture is jetted into the high temperature gas guided by the high temperature gas supply passage. Will be. The pulverized coal injected into the high-temperature gas is mixed with the high-temperature gas that is effective for releasing the volatile matter of the pulverized coal and heated, so the volatile matter is rapidly released and the pulverized coal particles are also heated. The On the other hand, since the hot gas has a low oxygen concentration and does not enter the flammable concentration range even when mixed with the carrier air, the released volatile matter is not burned in the hot gas supply passage.
Then, the low oxygen concentration pulverized coal mixture including the released volatile matter and the heated pulverized coal particles is ejected from the high temperature gas supply passage to the furnace, ignited, and the combustion air supplied to the outer peripheral portion Combustion is maintained while entraining. At this time, since the air amount as a whole is smaller than the theoretical air amount of pulverized coal, combustion is performed in a reducing atmosphere.

As described above, since the volatile matter is ejected to the furnace in a state where it has been released in advance, ignition is performed early as much as the time required for releasing the volatile matter necessary for conventional ignition becomes unnecessary. Further, since the pulverized coal particles are also heated in advance, they are ignited early because they reach the ignition temperature quickly. For this reason, since combustion at a high temperature and a low oxygen concentration starts earlier, the combustion time in such a reducing atmosphere becomes longer. For this reason, a sufficient reduction reaction time for NOx generated in a large amount in the early stage of combustion can be secured, so that the amount of NOx emission can be reduced.
Here, “high temperature effective for releasing volatile matter of pulverized coal” means, for example, a temperature of 750 ° C. or higher. With such a temperature, the volatile matter emission is completed before the pulverized coal enters the furnace, and the particles are sufficiently heated.
Further, the oxygen content of the high temperature gas is preferably 4% or less.

  Further, in the pulverized coal burner according to the present invention, in the pulverized coal burner in which an air amount smaller than the theoretical air amount of the pulverized coal amount to be input is introduced as a whole and burned in a reducing atmosphere, the pulverized coal of pulverized coal and carrier air is used. A pulverized coal mixture supply passage that guides the air-fuel mixture and ejects from the tip, and at least a tip portion of the pulverized coal mixture supply passage is provided, and guides a high-temperature gas that is 750 ° C. or higher and has a low oxygen concentration. A high-temperature gas supply passage that jets into the furnace and an air supply passage that is provided so as to cover at least the outer periphery of the tip of the high-temperature gas supply passage and supplies combustion air to the furnace.

According to the present invention, since the high temperature gas supply passage is provided so as to cover the tip portion of the pulverized coal mixture supply passage, the pulverized coal mixture is jetted into the high temperature gas guided by the high temperature gas supply passage. Will be. The pulverized coal injected into the high-temperature gas is heated by being mixed with a high-temperature gas having a temperature of 750 ° C. or higher, so that volatile matter is rapidly released and the pulverized coal particles are also heated. On the other hand, since the hot gas has a low oxygen concentration and does not enter the flammable concentration range even when mixed with the carrier air, the released volatile matter is not burned in the hot gas supply passage.
Then, the low oxygen concentration pulverized coal mixture including the released volatile matter and the heated pulverized coal particles is ejected from the high temperature gas supply passage to the furnace, ignited, and the combustion air supplied to the outer peripheral portion Combustion is maintained while entraining. At this time, since the air amount as a whole is smaller than the theoretical air amount of pulverized coal, combustion is performed in a reducing atmosphere.

  As described above, since the volatile matter is ejected to the furnace in a state where it has been released in advance, ignition is performed early as much as the time required for releasing the volatile matter necessary for conventional ignition becomes unnecessary. Further, since the pulverized coal particles are also heated in advance, they are ignited early because they reach the ignition temperature quickly. For this reason, since combustion at a high temperature and a low oxygen concentration starts earlier, the combustion time in such a reducing atmosphere becomes longer. For this reason, a sufficient reduction reaction time for NOx generated in a large amount in the early stage of combustion can be secured, so that the amount of NOx emission can be reduced.

  Furthermore, the pulverized coal burner according to the present invention is characterized in that a through-hole that is connected to the air supply passage is provided in the vicinity of the tip of the high-temperature gas supply passage.

  Thus, since the through-hole connected with the air supply passage is provided in the vicinity of the tip of the high-temperature gas supply passage, fuel air flowing through the air supply passage is supplied from the through-hole to the high-temperature gas supply passage. For this reason, a portion with a high oxygen concentration is formed in the pulverized coal mixture with a low oxygen concentration ejected from the high-temperature gas supply passage due to the supplied fuel air. It can be performed.

  A boiler according to the present invention includes the pulverized coal burner according to any one of claims 1 to 3, and an additional air nozzle that supplies fuel air into the furnace near the furnace outlet. To do.

Thus, since the pulverized coal burner which reduced NOx generation amount is employ | adopted, low NOx reduction is achieved as a boiler.
In order to reduce the amount of NOx generated, the amount of air input by the pulverized coal burner is about 70% of the theoretical air amount, and the amount of air supplied from the additional air nozzle is about 30% of the theoretical air amount. Is preferred.

In the pulverized coal burner according to the present invention, since the high-temperature gas supply passage is provided so as to cover the tip portion of the pulverized coal mixture supply passage, the NOx emission amount can be further reduced.
Moreover, since the pulverized coal burner is employed in the boiler according to the present invention, it is possible to further reduce NOx.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing an overall schematic configuration of a boiler 1 according to the present embodiment.
The boiler 1 includes a furnace 3 installed in a vertical direction, a combustion device 7 installed in a lower part of the furnace wall 5 of the furnace 3, a flue 9 connected to an outlet of the furnace 3, and an upper part of the furnace 3. A superheater 11, a reheater 13 and a economizer 15 provided over the flue 9, and a steam drum 17 provided at the upper part of the furnace 3 are 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 19 (see FIG. 2) 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 19. Pulverized coal supply means 21 for supplying, high temperature gas supply means 23 for supplying high temperature gas to the pulverized coal burner 19, and air supply means 23 for supplying combustion air to the pulverized coal burner 19 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 produced by the machine 27 is provided with a coal supply pipe 29 for air-flowing the pulverized coal as a pulverized coal mixture to the pulverized coal burner 19 by pressurized carrier 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 includes a not-shown push ventilator that pressurizes and supplies air, a wind box 31 provided on the outer wall of the furnace 3, and an air pipe that connects the push ventilator to the wind box 31 and the additional air nozzle 20. 33.
The tertiary air (combustion air) passing through the air pipe 31 is heat-exchanged with, for example, about 360 ° C. combustion exhaust gas passing through the flue 9 by the rotary regenerative heat exchanger 33 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 19. 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.

The pulverized coal burner 19 will be described with reference to FIG. FIG. 2 is a longitudinal sectional view showing a portion of the pulverized coal burner 19 on the furnace 3 side.
The pulverized coal burner 19 includes a pulverized coal supply pipe 43 that forms a pulverized coal mixture passage 41, a high-temperature gas supply pipe 45 provided so as to cover the pulverized coal supply pipe 43, and an outer periphery of the high-temperature gas supply pipe 45. A tertiary air supply pipe 47 provided so as to cover is provided.

The tertiary air supply pipe 47 has a hollow and substantially cylindrical shape and is provided so as to extend in the thickness direction of the furnace wall 5. The tertiary air supply pipe 47 is fixed to a hole formed through the furnace wall 5.
A tertiary air guide portion 49 is formed at the tip (furnace 3 side) portion of the tertiary air supply pipe 47 so as to gradually increase in diameter toward the furnace side. The tertiary air guide 49 plays a role of introducing tertiary air to the tip of the flame.
A tertiary air introduction part 51 is formed at the rear end (opposite side of the furnace 3) of the tertiary air supply pipe 47 so that the tertiary air is introduced into the tertiary air supply pipe 47 by the tertiary air swirl vane 53. It is configured.

The hot gas supply pipe 45 has a hollow and substantially cylindrical shape and is provided so as to extend in the thickness direction of the furnace wall 5.
A flame holding portion 55 that is gradually enlarged in diameter toward the furnace side is formed at the tip of the high temperature gas supply pipe 45. The rear end position of the flame holding portion 55 substantially coincides with the rear end position of the tertiary air guide portion 49.
At the rear end portion of the hot gas supply pipe 45, a hot gas introducing portion 57 having an enlarged diameter is formed. An exhaust gas pipe 37 is connected to the high temperature gas introduction part 57.
A space between the tertiary air supply pipe 47 and the high temperature gas supply pipe 45 constitutes a tertiary air passage (air supply passage) 59 for supplying the tertiary air introduced from the tertiary air introduction portion 51 to the furnace 3.

The pulverized coal supply pipe 43 has a hollow, substantially cylindrical shape and is provided so as to extend in the thickness direction of the furnace wall 5.
The pulverized coal supply pipe 43 is arranged such that the tip position is located at a substantially intermediate position in the longitudinal direction of the hot gas supply pipe 45.
The rear end portion of the pulverized coal supply pipe 43 is connected to the coal supply pipe 29. Inside the tip portion of the pulverized coal supply pipe 43, a density separator 61 is attached. The density separator 61 has a hollow, substantially cylindrical shape. An inclined portion 63 whose diameter gradually decreases toward the furnace 3 side is provided at the rear end portion of the density separator 61.

A heat insulating material 65 is attached to the inner peripheral side of the hot gas supply pipe 45 and the outer peripheral side of the pulverized coal supply pipe 43. The inside of the heat insulating material 65 constitutes a hot gas supply passage 67. Therefore, the hot gas supply passage 67 is formed so as to cover the tip portion of the pulverized coal mixture passage 41.
Near the tip of the hot gas supply pipe 45, the heat insulating material 65 is attached so that the thickness thereof gradually increases toward the furnace 3, and an inclined guide portion 69 for guiding the hot gas to the central portion is formed.
The heat insulating material 65 attached to the tip of the pulverized coal supply pipe 43 is provided with a truncated cone-shaped passage 71 whose diameter gradually increases toward the furnace 3 side. The passage 71 communicates with the pulverized coal mixture passage 41 and guides the pulverized coal mixture to the outer peripheral portion.
Between the inclination guide part 69 and the channel | path 71, the pulverized coal mixture is injected to high temperature gas, and the mixing part 73 in which both are mixed is formed.

The flame holding portion 55 of the high temperature gas supply pipe 45 is provided with a plurality of air supply holes 75 in the circumferential direction that penetrate through the heat insulating material 65 and communicate with the tertiary air passage 59 and the high temperature gas passage 67. Yes.
At the outer peripheral tip portion of the hot gas supply pipe 45, a flow dividing member 77 that covers each air supply hole 75, divides the tertiary air passage 59, and guides the tertiary air to the air supply hole 75 is attached.

The operation of the boiler 1 according to this embodiment described above will be described.
The pulverized coal generated by the pulverized coal machine 27 is mixed with the pressurized carrier air to form a pulverized coal mixture, and is sent to the pulverized coal mixture passage 41 of the pulverized coal burner 19 through the coal supply pipe 29. It is done.
The 800 ° C. combustion exhaust gas supplied through the exhaust gas pipe 37 is sent to the high temperature gas supply passage 67 as a high temperature gas. The pulverized coal mixture jetted from the pulverized coal mixture passage 41 is mixed with the high-temperature gas in the mixing unit and supplied from the flame holding unit 55 into the furnace 3.
Further, the tertiary air supplied by being pressurized by a not-shown forced draft fan is supplied with heat from the combustion exhaust gas by the rotary regenerative heat exchanger 35, is heated to 300 to 350 ° C., and flows through the air pipe 33. It is supplied to the box 31. The tertiary air is supplied from the wind box 31 through the tertiary air passage 59 of the pulverized coal burner 19 into the furnace 3.

As a result, flames are continuously generated in the furnace 3.
At this time, the amount of air input from the pulverized coal burner 19 is about 70% of the theoretical air amount of the amount of pulverized coal input for combustion, so combustion is performed in a reducing atmosphere. As a result, the amount of NOx generated in the early stage of pulverized coal combustion is reduced and the amount of NOx discharged to the downstream is reduced. Thereafter, about 30% of the theoretical air amount of tertiary air supplied from the additional air nozzle 20 provided in the vicinity of the outlet of the furnace 3 through the air pipe 33 is injected to perform oxidative combustion, thereby burning the unburned portion. Is going.

  When combustion is performed in the furnace 3 in this manner, the combustion gas flows from the bottom to the top in the furnace 3 and is discharged to the flue 9. At this time, water supplied from a water supply pump (not shown) is preheated by the economizer 15 and then supplied to the steam drum 17. The water supplied from the steam drum 17 to each water pipe (not shown) of the furnace wall 5 is heated to flow into the steam drum 17 while flowing through the water pipe from the bottom to the saturated steam. Further, the saturated steam of the steam drum 17 is introduced into the superheater 11 and is heated by the combustion gas. The superheated steam generated by the superheater 11 is supplied to a predetermined plant (for example, a turbine or the like).

In addition, the steam taken out in the middle of the expansion process in the turbine is introduced into the reheater 5 and reheated and returned to the turbine.
The combustion exhaust gas that has passed through the economizer 15 is supplied with heat to the secondary air that passes through the air pipe 33 in the rotary regenerative heat exchanger 35, and is subjected to treatments such as desulfurization, denitration, and dust removal. Released into the atmosphere.

Next, the operation of the pulverized coal burner 19 will be described.
The flow area of the pulverized coal mixture of about 80 ° C. supplied in the pulverized coal supply pipe 43 is gradually narrowed by the inclined portion 63 of the concentration separator 61, so that the flow velocity can be increased while being brought closer to the center side. . Then, when passing through the density separator 61, the flow area of the pulverized coal mixture is enlarged, so the flow velocity is reduced. As a result, the air with a small inertia force returns to the outer peripheral direction of the pulverized coal mixture passage 35, but the pulverized coal proceeds in a state where it is brought to the center because the inertia force is large. Therefore, a portion having a high pulverized coal concentration is formed on the center side of the pulverized coal mixture passage 41.

When the pulverized coal mixture is ejected from the pulverized coal mixture passage 41 in this state, the pulverized coal mixture is guided to the tip-like passage 71 and is ejected to the mixing unit 73 so as to expand to the outer peripheral side.
On the other hand, a high temperature gas having an oxygen concentration of 4% or less at 800 ° C. is led to the mixing portion 73 constituting the high temperature gas supply passage 67 toward the center side.
In this way, in the mixing section, the pulverized coal mixture flows so as to spread to the outer peripheral side, while the high temperature gas flows so as to narrow toward the center side, so that the pulverized coal mixture and the high temperature gas can be quickly and easily. Mixed.

When the pulverized coal mixture and the high-temperature gas are mixed in the mixing unit 73, the pulverized coal contained in the pulverized coal mixture is heated by the high-temperature gas, so that the volatile matter is rapidly released, and further the pulverized powder. Carbon particles are also heated.
On the other hand, since the oxygen concentration of the high-temperature gas is 4% or less, even if it is mixed with the carrier air, it does not enter the combustible concentration range of the volatile matter. For this reason, the volatile matter released from the pulverized coal is not burned in the high temperature gas supply passage 67.
The pulverized coal mixture A, which is mixed with the high-temperature gas in the mixing chamber 73 and is released, consisting of the released volatile matter, the heated pulverized coal particles, and air, is jetted from the flame holding portion 55 into the furnace 3.

At this time, the pulverized coal mixture A is supplied with tertiary air from the air supply holes 75 at a plurality of locations in the circumferential direction. The amount of air supplied from the air supply hole 75 is about 10% of the flow rate of the pulverized coal mixture A. Since the air supplied from the air supply hole 75 only needs to function as an ignition type, it is preferable to reduce it as much as possible in order to reduce NOx.
Therefore, the pulverized coal mixture A injected into the furnace 3 is in a state in which a portion where the pulverized coal particles are dense exists in the central portion and a portion where the oxygen concentration is dense extends in the ejection direction at a plurality of locations in the circumferential direction. ing.

The ejected pulverized coal mixture A is ignited to generate a flame. At this time, since a portion having a high oxygen concentration present at a plurality of locations in the circumferential direction becomes a fire type, stable ignition can be performed.
And combustion is maintained, entraining the tertiary air sent by the tertiary air guide part 49 to the front-end | tip part of a flame. At this time, the air amount as a whole is about 70% of the theoretical air amount of the pulverized coal, so that combustion occurs in a reducing atmosphere.
Furthermore, since the introduction of the tertiary air is the tip of the flame, the combustion up to that time is performed in a reducing atmosphere.

  As described above, since the pulverized coal mixture A is ejected to the furnace in a state where the volatile matter has been released in advance, the time required for releasing the volatile matter that has been required for conventional ignition becomes faster. It is ignited. Further, since the pulverized coal particles are also heated in advance, they are ignited early because they reach the ignition temperature quickly. For this reason, since combustion at a high temperature and a low oxygen concentration starts earlier, the combustion time in such a reducing atmosphere becomes longer. For this reason, a sufficient reduction reaction time for NOx generated in a large amount in the early stage of combustion can be secured, and the amount of NOx emission can be reduced.

  Further, since the pulverized coal mixture A has a thick portion of pulverized coal particles at the center, it becomes a so-called light and dark combustion state in which there is a concentration difference with the outer peripheral portion. For this reason, generation | occurrence | production of NOx can be reduced further.

In the present embodiment, combustion exhaust gas is used as the high-temperature gas, but the present invention is not limited to this. For example, it may be as shown in FIG.
In FIG. 3, the hot gas supply means 23 is supplied with a pressurized air blower (not shown), a combustor 81, an air pipe 83 connecting the forced air ventilator and the combustor 81, the combustor 81, and a high temperature. A combustion gas pipe 85 that connects the gas introduction part 57 is provided.
The air passing through the air pipe 83 is heat-exchanged with, for example, about 360 ° C. combustion exhaust gas passing through the flue 9 by the rotary regenerative heat exchanger 33, heated to 300 to 350 ° C., and supplied to the combustor 81. The In the combustor 81, the gas fuel 87 is blown and combusted with air, thereby generating a high-temperature gas having a temperature of, for example, 800 ° C. or more and an oxygen concentration of 4% or less. The generated hot gas is supplied to the hot gas supply passage 67 of the pulverized coal burner 19 through the combustion gas pipe 85.

If it does in this way, even if boiler output fluctuates, high temperature gas with a fixed condition can always be supplied. Thereby, the pulverized coal burner 19 can perform a stable operation.
Further, since the state of the high-temperature gas can be changed by changing the combustion conditions in the combustor 81, it is possible to cope with various boiler operating conditions.

1 is a block diagram showing an overall schematic configuration of a boiler according to an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the front-end | tip part of the pulverized coal burner concerning one Embodiment of this invention. It is a block diagram which shows another embodiment of a boiler.

Explanation of symbols

1 boiler 3 furnace 19 pulverized coal burner 41 pulverized coal mixture passage 59 tertiary air passage 67 hot gas supply passage 75 air supply hole

Claims (4)

In the pulverized coal burner, in which an amount of air smaller than the theoretical amount of pulverized coal to be charged is injected as a whole and burned in a reducing atmosphere,
A pulverized coal mixture supply path that guides the pulverized coal mixture of pulverized coal and carrier air and ejects from the tip;
A high-temperature gas supply passage that is provided so as to cover at least a tip portion of the pulverized coal mixture supply passage, and that introduces a high-temperature gas having a low oxygen concentration at a high temperature that is effective for releasing volatile matter of the pulverized coal and jets it to a furnace ,
An air supply passage that is provided so as to cover at least the outer periphery of the tip of the high-temperature gas supply passage, and supplies combustion air to the furnace;
A pulverized coal burner characterized by comprising: In the pulverized coal burner, in which an amount of air smaller than the theoretical amount of pulverized coal to be charged is injected as a whole and burned in a reducing atmosphere,
A pulverized coal mixture supply path that guides the pulverized coal mixture of pulverized coal and carrier air and ejects from the tip;
A high-temperature gas supply passage that is provided so as to cover at least a tip portion of the pulverized coal mixture supply passage and that guides a high-temperature gas that is 750 ° C. or higher and has a low oxygen concentration and jets it to the furnace
An air supply passage that is provided so as to cover at least the outer periphery of the tip of the high-temperature gas supply passage, and supplies combustion air to the furnace;
A pulverized coal burner characterized by comprising: The pulverized coal burner according to claim 1 or 2, wherein a through hole is provided in the vicinity of the tip of the high-temperature gas supply passage to communicate with the air supply passage. A pulverized coal burner according to any one of claims 1 to 3,
A boiler comprising an additional air nozzle for supplying fuel air into the furnace in the vicinity of the furnace outlet.

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