JP2010270990A - Fuel burner and turning combustion boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel burner for burning fine powder coal (solid fuel) capable of reducing an NOx generation amount by suppressing a high-temperature oxygen remaining area formed around the periphery of flame. <P>SOLUTION: In a fine powder coal burner 21 of the burner 20 for putting the fine power coal and air into a furnace of a boiler for burning the fine powder coal and burning it, a coal primary port 22 which conveys the fine powder coal by primary air and puts it into the furnace has a flow velocity adjustment part 24 for making the velocity distribution of an outlet flow velocity low at a flow passage cross-sectional center 22a. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a swirl combustion boiler that burns solid fuel such as pulverized coal.

Conventionally, solid fuel-fired boilers include, for example, coal-fired boilers that burn pulverized coal as solid fuel. In such a coal-fired boiler, two types of combustion systems are known: a swirl combustion boiler and an opposed combustion boiler.
Of these, in the pulverized coal-fired swirl combustion boiler, secondary air input ports for secondary air input are installed above and below the primary air input from the coal burner together with the pulverized coal of fuel. The flow rate is adjusted for the secondary air. (For example, see Patent Document 1)

The primary air described above is an amount of air necessary for conveying pulverized coal as fuel, and the amount of air is defined in a roller mill device that pulverizes coal into pulverized coal.
The secondary air mentioned above blows in the air quantity required in order to form the whole flame in a swirl combustion boiler. Therefore, the secondary air amount of the swirl combustion boiler is approximately the total air amount necessary for the combustion of the pulverized coal minus the primary air amount.

  On the other hand, in the burner of the opposed combustion boiler, it has been proposed to finely adjust the air introduction amount by introducing secondary air and tertiary air outside the primary air (pulverized coal supply). (For example, see Patent Document 2)

Japanese Patent No. 3679998 JP 2006-189188 A

By the way, in the conventional swirl combustion boiler described above, in order to reduce nitrogen oxides (NOx), in general, two-stage combustion using additional air (AA) is performed, and reduction combustion is performed in the vicinity of the burner. Has been done.
Further, in the conventional burner, a flame holding mechanism (adjustment of the tip corner, turning, etc.) is installed on the outer periphery of the pulverized coal burner, and further, the secondary air or the tertiary air is adjacent to the outer periphery of the pulverized coal burner. In general, a configuration in which an air input port for supplying air is installed is provided. For this reason, in the pulverized coal burner, the charged pulverized coal is ignited on the outer periphery of the flame, and a large amount of air is mixed in the ignition region on the outer periphery of the flame.

As a result, in the flame of the pulverized coal burner, a high-temperature oxygen residual region that generates NOx is formed on the outer periphery of the flame. This high temperature oxygen residual region is a flame outer periphery region where the oxygen concentration becomes high and combustion at a high temperature proceeds, and therefore, it is a combustion environment in which NOx is likely to be generated. Therefore, in the flame formed in the conventional pulverized coal burner, the amount of NOx generated from the outer periphery of the flame forming the high temperature oxygen residual region increases.
In this way, NOx generated from the outer periphery of the flame of the pulverized coal burner passes through the outer periphery of the flame as it is, so that the reduction is delayed as compared with the inside of the flame having a different combustion environment. As a result, NOx generated outside the flame remains without being reduced, and the remaining NOx is a cause of NOx generation in the conventional pulverized coal burner and the swirl combustion boiler.

From such a background, in a swirl combustion boiler that burns solid fuel such as pulverized coal, it is desired to suppress the high-temperature oxygen remaining region formed on the outer periphery of the flame and reduce the amount of NOx generated.
The present invention has been made in view of the above circumstances, and its object is to reduce the amount of NOx generated by suppressing (weakening) the high temperature oxygen remaining region formed on the outer periphery of the flame. Another object of the present invention is to provide a fuel burner and a solid fuel-fired swirl combustion boiler having the fuel burner.

In order to solve the above problems, the present invention employs the following means.
The fuel burner according to the present invention is a burner fuel burner for injecting and burning powdered fuel and air into a furnace of a boiler that burns powdered fuel. The fuel flow path to be provided with a flow rate adjusting portion for reducing the speed distribution of the outlet flow speed at the central portion of the cross section of the flow path is provided.

  According to such a fuel burner of the present invention, the flow rate adjustment is performed so that the velocity distribution of the outlet flow velocity is low at the center of the cross section of the flow channel in the fuel flow channel in which the pulverized fuel is transported by primary air and introduced into the furnace. Since the unit is provided, the flame can be held at a lower flow rate inside the flame. For this reason, the spread of the flame is suppressed, and the pulverized fuel is ignited inside the flame, so that NOx is generated inside the flame and quickly reduced.

  In the fuel burner, the flow rate adjusting unit includes a nozzle unit that narrows a tip of the fuel channel toward an outlet opening, and a partition member that divides the channel cross-sectional center at the tip of the fuel channel. It is preferable that the cross-sectional area of the central portion of the flow path cross section is constant in the flow direction. It is possible to form an outlet flow velocity distribution with a relatively low flow velocity at the center of the cross section of the flow path.

  In the fuel burner described above, it is preferable to provide a diffuser part in which the cross-sectional area of the flow path cross-sectional center part is enlarged toward the outlet opening side at the outlet side tip part of the partition member. Not only can be further reduced, but also the flow can be disturbed.

  In the fuel burner described above, it is preferable to employ a split member having a flame holding function as the partition member, and this enables stable ignition by an internal flame holding mechanism formed in the fuel burner.

  In the swirl combustion boiler according to the present invention, the burner for charging pulverized fuel and air into the furnace is a burner unit of a swirl combustion method in which each burner portion is disposed at each corner portion or wall surface portion. In a swirl combustion boiler in which a plurality of swirl flames are formed, the burner includes a fuel burner according to any one of claims 1 to 4 and a flow rate adjusting means 2 disposed above and below or right and left of the fuel burner. And a secondary air input port.

  According to such a swirl combustion boiler of the present invention, since the burner includes the fuel burner according to any one of claims 1 to 4, the outlet flow velocity of the fuel burner is a low speed at the center of the flow path cross section. Distribution. For this reason, since the flame can be held at a lower flow rate inside the flame, the spread of the flame is suppressed. Moreover, since the pulverized fuel is ignited inside the flame, NOx is generated inside the flame and quickly reduced.

  In the swirl combustion boiler described above, the secondary air that is input from the secondary air input port to the flame formed from the fuel burner into the furnace is provided between the fuel burner and the secondary air input port. It is preferable to provide a separation distance so as not to interfere with each other, thereby slowing the supply of secondary air to the flame from the secondary air input port to lower the oxygen concentration in the flame and reducing the flame by the low-temperature secondary air. Temperature drop (cooling) can be minimized.

In the above swirl combustion boiler, it is preferable that the secondary air input port is installed so as to have an outward angle with respect to the axial center of the fuel burner, whereby the installation position of the secondary air input port is determined. Even if it is close to the fuel burner, the secondary air input from the secondary air input port does not interfere with the flame formed from the fuel burner into the furnace, so that the burner height can be reduced.
Further, when the secondary air input port is adjacent, the mixing of the secondary air and the flame can be delayed by injecting the secondary air obliquely with respect to the flame.

In the above-described swirl combustion boiler, a rib may be provided inside the flow path of the secondary air input port, or a swirl blade may be provided.
Here, by providing a rib inside the flow path of the secondary air input port, for example, on the inner side (fuel burner side) of the flow path, the mixing of the secondary air to the flame can be adjusted. Further, by providing a swirling impeller inside the flow path, it is possible to suppress the burner height and separate the flow so that the flow of secondary air does not interfere with the flame.

According to the present invention described above, in a swirl combustion boiler that burns solid fuel such as pulverized coal, the remarkable effect of suppressing the high temperature oxygen remaining region formed on the outer periphery of the flame and reducing the amount of NOx generated can be obtained.
That is, the fuel burner of the present invention is provided with a flow rate adjusting part in the fuel flow path for introducing the pulverized fuel into the furnace, and forms a speed distribution in which the outlet flow speed at the center of the flow path cross section becomes low. The flame is held by lowering the flow rate of the pulverized fuel introduced therein, so that the spread of the flame can be suppressed, and the pulverized fuel can be stably burned even in a low oxygen concentration environment. Since the pulverized fuel is ignited inside the flame, the NOx generated inside the flame is quickly reduced and the emission amount is reduced.

  In addition, since the secondary air is slowly supplied from the secondary air input port arranged so as not to interfere with the flame, the temperature drop (cooling) of the flame due to the low temperature secondary air is minimized, Despite the lack of air in the flame, stable ignition is continued while maintaining a high temperature flame. Therefore, the swirl combustion boiler according to the present invention can be burned in an environment of high temperature and low oxygen concentration, and can be burned with greatly reduced NOx and unburned content.

It is a figure which shows one Embodiment of the fuel burner which concerns on this invention, (a) is a longitudinal cross-sectional view of the burner structure comprised by a fuel burner and a secondary air injection port, (b) is a burner structure of (a). The front view seen from the inside of a furnace, (c) is explanatory drawing which shows the flow velocity distribution of the exit flow velocity in a fuel burner, (d) is a longitudinal cross-sectional view which shows the modification of a call secondary port. FIG. 2 is a secondary air supply system diagram for the burner structure shown in FIG. It is a longitudinal section showing an example of composition of a swirl combustion boiler concerning the present invention. FIG. 4 is a horizontal (horizontal) cross-sectional view of FIG. 3. It is a longitudinal cross-sectional view which shows the example of a burner structure provided with the fuel burner of the 1st modification. It is a longitudinal cross-sectional view which shows the example of a burner structure provided with the fuel burner of the 2nd modification. It is a longitudinal cross-sectional view which shows the example of a burner structure provided with the secondary air injection port of the 1st modification. It is a longitudinal cross-sectional view which shows the example of a burner structure provided with the secondary air injection port of the 2nd modification. It is a longitudinal cross-sectional view which shows the example of a burner structure provided with the secondary air injection port of the 3rd modification. It is a figure which shows the example of a burner structure provided with the secondary air injection port of the 4th modification, (a) is a top view of a burner structure, (b) is the front view which looked at the burner structure from the inside of a furnace. It is a top view which shows the example of a burner structure provided with the secondary air injection port of the 5th modification.

Hereinafter, an embodiment of a combustion burner and a swirl combustion boiler according to the present invention will be described with reference to the drawings.
The swirl combustion boiler 10 shown in FIG. 3 and FIG. 4 reduces the region from the burner unit 12 to the additional air input unit (hereinafter referred to as “AA unit”) 14 by inputting air into the furnace 11 in multiple stages. The atmosphere is designed to reduce NOx in combustion exhaust gas. As for the distance from the burner section 12 to the AA section 14 serving as the reducing atmosphere, that is, the distance (height) of the reducing combustion zone, the longer the residence time of the combustion gas becomes, the smaller the NOx generation amount becomes. In the figure, reference numeral 20 denotes a burner that inputs pulverized fuel such as pulverized coal and air, and 15 is an additional air input nozzle that inputs additional air.

  In the following embodiments, the swirl combustion boiler 10 will be described as pulverized coal burning using pulverized coal as pulverized fuel, but is not limited thereto. Therefore, the pulverized coal-burning burner 20 is connected to the pulverized coal mixture transport pipe 16 that transports the pulverized coal with primary air and the air supply duct 17 that supplies the secondary air. An air supply duct 17 for supplying secondary air is connected.

  In this way, the above-described swirl combustion boiler 10 is a swirl combustion type burner unit 12 in which the burners 20 for introducing pulverized coal (powder fuel) and air into the furnace 11 are arranged at each corner of each stage. In each stage, a swirl combustion method is employed in which one or a plurality of swirl flames (one in the illustrated example) are formed. That is, in the swirl combustion boiler 10 shown in FIG. 3 and FIG. 4, the burner 20 for introducing pulverized coal and air into the furnace 11 (inside the furnace) has a substantially square cross-sectional shape in each furnace 11. One swirl flame is formed by being arranged at each corner. However, in the present invention described below, for example, by arranging the burner 20 on the corner portion and the wall surface portion in the furnace 11 having a rectangular cross-sectional shape, the burner portion or the like of the swirl combustion method that forms two swirl flames. Is also applicable and is not particularly limited.

In the swirl combustion boiler 10 of the present embodiment, each burner 20 of the burner unit 12 includes a pulverized coal burner (fuel burner) 21 for introducing pulverized coal and air, and a pulverized coal burner 21 as shown in FIG. And a secondary air inlet port 30 for injecting secondary air, which is arranged above and below.
The pulverized coal burner 21 is provided so as to surround the rectangular primary coal port 22 for introducing the pulverized coal conveyed by the primary air and the primary coal port 22, and a part of the secondary air is introduced. The call secondary port 23 is provided. The pulverized coal charged from the pulverized coal burner 21 flows substantially straight toward the furnace 11.

Secondary air input ports 30 are provided substantially in parallel above and below the pulverized coal burner 21 for supplying secondary air. The secondary air input port 30 is divided into independent flow paths and ports, and the secondary air input from the secondary air input port 30 flows substantially straight into the furnace 11.
As shown in FIG. 2, for example, as shown in FIG. 2, the flow rate adjusting means of the secondary air supplied to each flow path of the secondary air input port 30 and the call secondary port 23 through flow paths branched from the air supply duct 17. As shown in FIG. In addition, about the position of the secondary air injection | throwing-in port 30, it is not limited to the upper and lower sides of the pulverized coal burner 21, and may be right and left.

In the illustrated configuration example, the pulverized coal burner 21 of the burner 20 inputs and burns pulverized coal and air into the furnace 11 of a coal-fired boiler using a swirl combustion method. A coal primary port 22 serving as a fuel flow path to be introduced into the furnace 11 is provided with a flow speed adjusting section 24 for reducing the speed distribution of the outlet flow speed at the center of the cross section of the flow path. The flow rate adjusting unit 24 flows at the nozzle portion 25 that narrows the fuel flow path formed in the primary coal port 22 toward the outlet opening, and the front end of the fuel flow channel formed in the primary coal port 22. And a partition member 26 for dividing the road cross-section central portion 22a.
In the configuration example shown in FIG. 1 (a), the call secondary port 23 is formed substantially parallel to the aperture of the nozzle portion 25. For example, as shown in FIG. It is preferable to feed it almost straight inward. That is, when the outlet of the coal secondary port 23 is inclined in the axial center direction, the coal secondary air is introduced toward the pulverized coal that is introduced almost straight from the pulverized coal burner 21 into the furnace 11. Therefore, the secondary air of coal acts in the direction to blow out the flame.

The nozzle portion 25 is a portion that is narrowed so that the cross-sectional area of the flow path gradually decreases at the tip portion where the coal primary port 22 opens into the furnace 11. In the illustrated configuration example, the nozzle portion 25 is located above and below the pulverized coal burner 21. The member is inclined toward the center of the channel cross section to narrow the channel cross sectional area. Accordingly, the secondary port 23 formed above and below the primary call port 22 also has no change in the flow passage cross-sectional area, but the secondary air outflow direction is inclined from the parallel to the flow passage cross-sectional center direction. .
The partition member 26 is, for example, a pair of plate-like members arranged in parallel in the horizontal direction with a predetermined interval a, and the flow path cross-sectional area of the flow path cross-sectional central portion 22a is constant in the flow direction in the fuel flow path. ing. It is desirable that the partition member 26 is extended to the upstream side from the position at which the restriction of the nozzle portion 25 is started in order to suppress an increase in the flow velocity at the center. Note that nozzle outlets 22b of the nozzle portion 25 whose flow path cross-sectional area is narrowed are opened above and below the flow path cross-sectional central portion 22a partitioned by the partition member 26.

The pulverized coal burner 21 configured in this way increases the flow velocity at the upper and lower nozzle outlets 22b that are increased by the decrease in the flow path cross-sectional area, whereas the flow path cross-sectional center part 22a has no fluctuation in the flow path cross-sectional area. Then there is almost no fluctuation of the flow velocity. As a result, for example, as shown in FIG. 1 (c), compared with the upper and lower nozzle outlets 22b whose flow velocity is increased by decreasing the flow passage cross-sectional area, the flow passage cross-section central portion 22a has no fluctuation. A flow velocity distribution with a relatively low outlet flow velocity is formed.
In the example shown in FIG. 1C, when the nozzle section 25 restricts the channel cross-sectional area to 1/3 and the channel cross-section central portion 22a and the nozzle outlet 22b have the same outlet area, that is, the channel cross-section central portion 22a. An example of velocity distribution when the outlet cross-sectional area is set to 1/3 of the entire outlet area is shown. In this velocity distribution example, the outlet flow velocity (Vc) at the flow path cross-section central portion 22a is lower than the upper and lower outlet flow velocity (Vo) (Vc <Vo).
In addition, when the partition member 26 is only on the outlet side from the throttling start position of the nozzle portion 25, the pressure loss increases as the flow passage cross-sectional area of the nozzle outlet 22b becomes narrower. The flow rate increases.

  In such a pulverized coal burner 21, the flow rate adjusting unit 24 provided in the fuel flow channel for conveying the pulverized coal with primary air and putting it into the furnace 11 causes the flow velocity distribution of the outlet flow velocity to be relative to the flow channel cross-sectional central portion 22 a. Therefore, the flow velocity inside the flame is lowered, that is, the flow velocity of the pulverized coal injected near the axial center of the flame formed from the axial center of the pulverized coal burner 21 toward the inside of the furnace 11 is reduced. Thus, it is possible to hold the flame while suppressing the spread of the flame. In other words, since the flow velocity in the direction in which the flame is expanded outward from the flame center is increased, the spread of the flame is suppressed and flame holding becomes possible. Moreover, since the pulverized coal introduced near the center of the flame is ignited near the center of the flame, NOx is generated inside the flame and is quickly reduced.

Further, between the fuel burner 21 and the secondary air input port 30, the secondary air input from the secondary air input port 30 does not interfere with the flame formed from the fuel burner 21 into the furnace 11. The separation distance L is provided. This separation distance L is used to slow down the supply of secondary air introduced from the secondary air introduction port 30 to lower the oxygen concentration in the flame. In other words, the separation distance L is low temperature secondary air. Is a moderate distance that is difficult to reach the flame. That is, the separation distance L is a distance that can suppress mixing of the secondary air into the flame, and the height dimension h of the fuel burner 21 depends on various conditions such as the pressure at which the secondary air is introduced. About 1 h to 3 h are required on the basis of (see FIG. 1).
By providing such a separation distance L, the amount of secondary air mixed into the flame is reduced, so that the oxygen concentration in the flame is reduced, and the temperature of the flame is kept relatively low while minimizing the drop in the flame temperature. Can be maintained.

In the burner 20 configured in this way, with respect to the flow of pulverized coal flowing in the primary coal port 22, the flow rate adjusting unit 24 sets the outlet flow rate at the flow path cross-sectional center portion 22 a to a relatively low state, and then the inside of the flame. Since the fuel is fed toward the, the flow velocity inside the flame is also reduced and the flame is held. For this reason, the flame does not spread greatly, and the pulverized coal is ignited and burned inside the flame, so that NOx is generated inside the flame and is quickly reduced.
At this time, since the separation distance L provided between the pulverized coal burner 21 and the secondary air input port 30 suppresses interference between the flame and the secondary air, the pulverized coal that ignites at the center of the flame is Since secondary air is slowly supplied from the secondary air input port 30 to the flame, it burns in a state where the oxygen concentration inside the flame is low.

  Further, since the secondary air is slowly supplied from the secondary air input port 30 arranged with a separation distance L, the temperature drop of the flame due to the low temperature secondary air can be minimized, Even though the flame is short of air and has a low oxygen concentration, the flame is heated to a stable temperature and continues to ignite stably, enabling combustion at a high temperature and a low oxygen concentration. That is, since the local high-temperature oxygen remaining region formed on the outer periphery of the flame is suppressed and becomes small and weak, it is possible to perform combustion with greatly reduced NOx and unburned content.

By the way, even if the pulverized coal burner 21 of the burner 20 described above is added with a diffuser portion 27 that expands the cross-sectional area of the flow path cross-sectional central portion 22a to the outlet opening side as in the first modification shown in FIG. Good. That is, the partition member 26A of the flow velocity adjusting unit 24A may be provided with a diffuser portion 27 that expands the cross-sectional area of the flow path cross-sectional central portion 22a toward the outlet opening side at the outlet side tip portion. By providing, the outlet flow velocity of the channel cross-section central portion 22a decreases as the channel cross-sectional area increases. For this reason, since the relative outlet flow velocity can be further reduced, the flame holding and the NOx generation amount reducing action are further improved.
Furthermore, since the diffuser part 27 disturbs the flow of pulverized coal that is introduced from the nozzle outlet 22b in particular, the ignitability inside the flame can be improved.

  Further, the pulverized coal burner 21 of the burner 20 described above may employ a pair of split members 28 having a flame holding function instead of the partition member 26 described above, for example, as in the second modification shown in FIG. Good. In the flow velocity adjusting unit 24B employing such a split member 28, the split member 28 disposed at the front end outlet portion of the pulverized coal burner 21 forms an internal flame holding mechanism, so that stable ignition can be maintained. .

Subsequently, the burner 20A shown in FIG. 7 shows a burner structure example provided with the secondary air input port 30A of the first modified example.
In this modification, the secondary air input port 30A of the burner 20A is installed inclining by an angle θ from the burner outer wall 21a parallel to the axial center of the pulverized coal burner 21 in the vertical direction. In addition, although the pulverized coal burner 21 of the 2nd modification shown in FIG. 6 is employ | adopted for the structural example shown in FIG. 7, it is not limited to this, Embodiment and the 1st modification mentioned above and It's okay to make a mistake.

As described above, when the secondary air input port 30 </ b> A that is inclined outward in the vertical direction is employed, even if the installation position of the secondary air input port 30 </ b> A is close to the pulverized coal burner 21, the pulverized coal burner 21 enters the furnace 11. Since the secondary air that is input from the secondary air input port 30A does not interfere with the flame that is formed to face the burner, the burner height can be reduced. That is, since the secondary air input from the secondary air input port 30A flows in a direction away from the flame, when comparing with the same specifications, the maximum separation distance L1 shown in FIG. It becomes possible to set smaller than the distance L.
As a result, the burner 20 in which the secondary air input port 30A is disposed above and below the pulverized coal nozzle 21 can reduce the overall height of the burner 20 by reducing the separation distance L1.

  Further, in the second modification of the secondary air input port shown in FIG. 8, ribs 31 are provided inside the flow path of the inclined secondary air input port 30A. That is, in the illustrated example, the rib 31 is provided inside the outlet of the secondary air input port 30A (the pulverized coal nozzle 21 side), and the flow of the secondary air is caused by colliding the flow of the secondary air with the rib 31. Changes have been made. In particular, the rib 31 provided inside the outlet of the secondary air input port 30A changes the flow of the secondary air in a direction away from the flame. Therefore, by appropriately adjusting the height of the rib 31 and the like, The mixing of the secondary air can be adjusted.

Further, in the third modification of the secondary air input port shown in FIG. 9, a plurality of swirl vanes 32 are provided in the flow path of the secondary air input port 30B. The secondary air input port 30 </ b> B in this case is formed in parallel with the axis of the pulverized coal burner 21. A swirl vane 32 is provided in the flow path of the secondary air input port 30B. The swirl vane 32 has, for example, an airfoil cross section, and can efficiently separate the secondary air flow from the flame.
By adopting such a configuration, it is possible to keep the burner height to a minimum and to separate the secondary air flow so as not to interfere with the flame.

  Further, the fourth modification of the secondary air input port shown in FIG. 10 is a case where the secondary air input port 30C includes the adjacent left outlet 30L and right outlet 30R, and the secondary air is used as a flame. In contrast, the mixing of the secondary air and the flame can be delayed by throwing it at an angle. That is, in the fourth modification shown in FIG. 10 (a), the secondary air input port for supplying secondary air into the furnace 11 from the left outlet 30L and the right outlet 30R when the plan view branches in a Y shape. The left air outlet 30L and the right air outlet 30R that are inclined to the left and right direction from the axis of the pulverized coal burner 21 are arranged adjacent to each other, so the secondary air flows out in a direction away from the flame. Mixing is delayed.

  Further, also in such a secondary air input port 30C, for example, as in the fifth modification of the secondary air input port shown in FIG. 11, the outlet inner side of the left outlet 30L and the right outlet 30R (pulverized coal nozzle 21 You may provide the rib 31 in the axial center side). By providing such a rib 31, the flow of secondary air collides with the rib 31 and changes the flow. Therefore, when the delay in mixing the secondary air is large, the height of the rib 31 is appropriately adjusted. Thus, the mixing of secondary air to the flame can be adjusted.

  Thus, according to the above-described embodiment and the swirl combustion boiler 10 of each modification, in the swirl combustion boiler that burns solid fuel such as pulverized coal, the high temperature oxygen remaining region formed on the outer periphery of the flame is suppressed and NOx is reduced. The amount generated can be reduced. That is, the pulverized coal (powder fuel) input from the pulverized coal burner 21 has a low flow rate input to the center of the flame by the flow rate adjusting unit 24, so that the flame spread is suppressed and ignited inside the flame. Thus, NOx generated in the flame can be quickly reduced to reduce the amount of NOx generated.

  Further, since the secondary air is slowly supplied from the secondary air input port 30 arranged so as not to interfere with the flame, the temperature drop (cooling) of the flame due to the low-temperature secondary air is minimized. be able to. Therefore, stable ignition can be continued while maintaining a high-temperature flame even in a flame where the supply of secondary air is slow and the air is insufficient. Therefore, the swirl combustion boiler 10 of the present invention can combust pulverized fuel such as pulverized coal even in an environment of high temperature and low oxygen concentration, and combustion with significantly reduced NOx and unburned content is possible. become.

By the way, each embodiment and modification mentioned above can be combined suitably besides having been demonstrated based on illustration. Further, in the above-described embodiment, the swirl combustion boiler 10 in which the region from the burner portion 12 to the AA 14 is used as a reducing atmosphere in the reducing atmosphere is described, but the present invention is not limited to this.
In addition, this invention is not limited to embodiment mentioned above, For example, pulverized fuel is not limited to pulverized coal, For example, it can change suitably in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 10 Swirling combustion boiler 11 Furnace 12 Burner part 14 Additional air injection part (AA part)
20, 20A Burner 21 Pulverized coal burner (fuel burner)
22 Cole primary port (fuel flow path)
23 Cole secondary port 24, 24A, 24B Flow rate adjustment part 25 Nozzle part 26, 26A Partition member 27 Diffuser part 28 Split member 30, 30A, 30B, 30C Secondary air input port 31 Rib 32 Swivel blade

Claims (9)

  A fuel burner of a burner that injects and burns pulverized fuel and air into a furnace of a boiler that burns pulverized fuel, into a fuel flow path that conveys the pulverized fuel with primary air and inputs it into the furnace. A fuel burner comprising a flow rate adjusting unit for reducing the velocity distribution of the outlet flow rate at the center of the cross section of the flow path.   The flow rate adjusting unit includes a nozzle part that narrows a tip part of the fuel flow path toward an outlet opening, and a partition member that divides the flow path cross-sectional center part at the tip part of the fuel flow path. The fuel burner according to claim 1, wherein a cross-sectional area of a central portion of the cross section is constant in a flow direction.   3. The fuel burner according to claim 2, wherein a diffuser portion that expands a cross-sectional area of the flow path cross-sectional central portion toward an outlet opening side is provided at an outlet-side tip portion of the partition member.   The fuel burner according to claim 2, wherein the partition member is a split member having a flame holding function. The burner for charging pulverized fuel and air into the furnace is a swirl combustion type burner portion disposed at each corner portion or wall surface portion of each stage, and the swirl where one or more swirl flames are formed at each stage. In the combustion boiler,
The burner comprises: the fuel burner according to any one of claims 1 to 4; and a secondary air input port having a flow rate adjusting means disposed on the top and bottom or the left and right of the fuel burner, respectively. Swirl combustion boiler.   A separation distance between the fuel burner and the secondary air input port so that the secondary air input from the secondary air input port does not interfere with a flame formed from the fuel burner into the furnace. The swirl combustion boiler according to claim 5, wherein   The swirl combustion boiler according to claim 6, wherein the secondary air input port is installed so as to have an outward angle from an axial center of the fuel burner.   The swirl combustion boiler according to any one of claims 5 to 7, wherein a rib is provided inside a flow path of the secondary air input port. The swirl combustion boiler according to any one of claims 5 to 7, wherein swirl vanes are provided inside the flow path of the secondary air input port.

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