JP5386230B2 - Fuel burner and swirl combustion boiler - Google Patents

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 fed into the fuel flow path is provided with a guide for narrowing the angle in the flow direction toward the flow path cross-sectional central part, and the guide has a blade cross-sectional shape protruding inward. is there.

According to such a fuel burner of the present invention, the guide for narrowing the angle in the flow direction toward the center of the cross section of the flow path at the front end of the fuel flow path where the pulverized fuel is transported by primary air and introduced into the furnace. Therefore, it is possible to form a concentrated flame at the center of the flame at the tip of the burner and hold 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.
Since the guide has an inwardly convex blade cross-sectional shape, the pulverized fuel is entrained by lowering the static pressure inside the guide (flow passage cross-section center side). A rich flame can be formed well.

  In the fuel burner described above, the angle α for narrowing the guide is preferably set to 20 degrees or more. As a result, a vortex is generated in the separation region and the flow is disturbed, so that the ignitability can be improved.

In the fuel burner described above, it is preferable to provide a rib at the tip of the guide, whereby the turbulence of the flow can be further promoted to improve the ignitability.
In the fuel burner, the guide position is preferably set such that the axial distance X from the burner tip position to the guide tip is set to be not less than twice the burner height dimension h (X ≧ 2h). The flow rate of the part can be reduced.

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, the burner is a fuel burner according to any one of claims 1 to 4 , and secondary air having flow rate adjusting means arranged above and below or on the left and right of the fuel burner. Since the injection port is provided, it is possible to hold the flame by forming a concentrated flame at the center of the flame at the tip of the burner. 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 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-described swirl combustion boiler, it is preferable that the secondary air input port is installed at an angle θ outward from the axial center of the fuel burner. Even if the fuel is close to the fuel burner, the secondary air introduced 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 includes a guide for narrowing the angle of the flow direction toward the center of the cross section of the flow path at the front end of the fuel flow path where the pulverized fuel is conveyed by primary air and introduced into the furnace. Therefore, concentrated powder can be formed in the center of the flame to hold the powder by intensively charging the pulverized fuel from the tip of the burner into the center of the flame. For this reason, the spread of the flame is suppressed, the powdered fuel can be stably burned even in a low oxygen concentration environment, and the powdered fuel is ignited inside the flame, so that it occurred inside the flame. NOx is rapidly 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). It is the front view seen from the inside of a furnace. FIG. 2 is a secondary air supply system diagram for the burner structure shown in FIG. 1. 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. (A) is a longitudinal cross-sectional view which shows the example of a burner structure provided with the fuel burner of the 1st modification, (b) is a longitudinal cross-sectional view which shows the modification regarding a guide installation position. 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 section 12 to the additional air input section (hereinafter referred to as “AA section”) 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 guide 24 that narrows the angle in the flow direction toward the center of the cross section of the flow path is provided at the distal end of the primary call port 22 that becomes the fuel flow path to be introduced into the furnace 11. A pair of upper and lower guides 24 are provided in the call primary port 22.

The guide 24 has a blade cross-sectional shape (curved surface) that protrudes inward (flow passage cross-section center side), and lowers the static pressure on the flow passage cross-section center side (inside) that is the inner side between the pair of upper and lower guides 24.
For this reason, the pulverized coal can be efficiently collected in the central portion of the coal primary port 22 by entraining the pulverized coal in the region on the flow path cross-sectional center side where the static pressure is reduced. That is, the flow path cross-sectional area formed between the pair of upper and lower guides 24 is narrowed by the guide 24 inclined at an angle α from the upstream side to the downstream side. It is possible to collect and centrally charge into the center of the flame. However, by using the guide 24 with the blade cross section, it is possible to concentrate the pulverized coal with a higher degree of concentration.

  Therefore, the above-described pulverized coal burner 21 is provided with the guide 24 for narrowing the flow direction angle α toward the flow path cross-section central portion at the front end portion of the primary coal port 22, and therefore, from the front end of the burner 20 to the flame central portion. By intensively introducing pulverized coal, it becomes possible to form a rich flame at the center of the flame and hold the flame. For this reason, since the spread of the flame is suppressed and the pulverized coal is ignited inside the flame, the NOx generated by the combustion is generated inside the flame and quickly reduced.

By the way, although the guide 24 of the above-described embodiment has been described as having an inwardly convex blade cross-sectional shape, it is not limited to this, for example, a plate material inclined at an angle α can be adopted. .
Moreover, in the pulverized coal burner 21 described above, it is desirable that the angle α for narrowing the guide 24 is set to be larger than 20 degrees. This is because the outer side of the guide 24 becomes a separation region, and a vortex is generated in the separation region to disturb the flow, which is effective in improving the ignitability. The generation of such vortices becomes more prominent as the angle α is larger.

  In addition, in the fuel burner 21 of the first modification shown in FIG. 5A, a rib 25 is provided at the tip of the guide 24. The rib 25 is a portion that protrudes to the inside of the distal end portion of the guide 24 and obstructs the flow of pulverized coal flowing between the pair of upper and lower guides 24. For this reason, the flow of pulverized coal that has been squeezed between the pair of upper and lower guides 24 to cause turbulence is further disturbed by the ribs 25. That is, the rib 25 can further promote the turbulence generated in the flow of the pulverized coal, and can further improve the ignitability of the pulverized coal put into the flame.

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.

As described above, the pulverized coal burner 21 described above is provided with the guide 24, so that the pulverized coal is concentratedly introduced from the tip of the burner 20 to the center of the flame, thereby forming a concentrated flame at the center of the flame and holding the flame. be able to. For this reason, the spread of the flame is suppressed, the pulverized coal can be stably burned even in the combustion environment inside the flame with a low oxygen concentration, and the pulverized coal is ignited inside the flame, so that NOx generated inside the flame is reduced. It reduces quickly and reduces NOx generation.
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, combustion with significantly reduced NOx and unburned content becomes possible.

FIG. 5B is a longitudinal cross-sectional view showing a modified example related to the installation position of the guide 24. In this modification, the position of the guide 24 is set such that the axial distance X from the burner tip position to the guide tip is at least twice the burner height dimension h (X ≧ 2h). As a result, since the flow velocity is reduced in the central portion of the primary call channel 22, even if the installation angle of the burner 20 is changed in the vertical direction, that is, the burner 20 is installed at an angle in the vertical direction from the horizontal arrangement. Even so, stable shading separation is possible.
In the illustrated configuration example, the guide 24 is installed in the pulverized coal pipe 26 at a position having a sufficient distance upstream from the tip of the pulverized coal burner 21. Reference numeral 27 in the drawing denotes a partition plate provided from the tip of the guide 24 to the burner tip position, and a rib 25 is provided at the tip of the partition plate 27.

Subsequently, the burner 20A shown in FIG. 6 shows a burner structure example provided with the secondary air input port 30A of the first modification.
In this modification, the secondary air input port 30A of the burner 20A is installed at an angle θ from the burner outer wall 21a parallel to the axial center of the pulverized coal burner 21 in the vertical direction. The configuration example shown in FIG. 6 employs the pulverized coal burner 21 of the first modification shown in FIG. 5, but is not limited to this, and the embodiment and the first modification described 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. 7, 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 modified example of the secondary air input port shown in FIG. 8, 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.

Moreover, the 4th modification of the secondary air injection | throwing-in port shown in FIG. 9 is a case where the secondary air injection | throwing-in port 30C is equipped with the adjacent left blower outlet 30L and the right blower outlet 30R, and makes secondary air into 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. 9 (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.

  Also in such a secondary air input port 30C, as in the fifth modification of the secondary air input port shown in FIG. 10, for example, 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 (pulverized fuel) introduced from the pulverized coal burner 21 forms a concentrated flame by the concentrated introduction to the center of the flame by the guide 24, so that the flame spread is suppressed and the flame interior is suppressed. 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. For this reason, 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 20,20A Burner 21 Pulverized coal burner (fuel burner)
22 Cole primary port (fuel flow path)
23 Cole secondary port 24 Guide 25, 31 Rib 30, 30A, 30B, 30C Secondary air input port 32 Swivel blade

Claims (9)

A fuel burner of a burner that injects and burns pulverized fuel and air into a furnace furnace of a pulverized fuel conveys the pulverized fuel by primary air and inputs it into the furnace. And a guide for narrowing the flow direction angle toward the center of the cross section of the flow path ,
A fuel burner characterized in that the guide has an inwardly convex blade cross-sectional shape . The fuel burner according to claim 1, wherein an angle α for narrowing the guide is set to 20 degrees or more. The fuel burner according to claim 1 or 2, wherein a rib is provided at a tip portion of the guide. The position of the guide, either from the burner tip position guide tip axial distance X to more than twice the burner height h (X ≧ 2h) that are set in claims 1, wherein the third Crab fuel burner. 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 is such 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, which is provided. The swirl combustion boiler according to claim 6 , wherein the secondary air input port is installed at an angle θ outward from the 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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