JP2010139182A - Turning combustion boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turning combustion boiler capable of reducing a NOx generation amount by suppressing a high temperature oxygen remaining region formed on the outer periphery of flame. <P>SOLUTION: In the turning combustion boiler, in a burner in a turning combustion method, the burner 20 charging pulverized coal and air into a furnace is arranged at each corner at each stage, and one or a plurality of turning flames are formed at each stage. The burner 20 includes a pulverized coal burner 21 charging pulverized coal and air and a secondary air charging port 30 for charging secondary air and arranged around the pulverized coal burner 21. The pulverized coal burner 21 includes a kick mechanism 40 for blowing in part of charged pulverized coal toward the high temperature oxygen remaining region H at the external periphery of the flame F. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

Conventionally, swirl combustion boilers and counter combustion boilers are known as pulverized coal fired boilers.
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. The secondary air input port for inputting secondary air may also serve as an oil burner.

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 1)
JP 2006-189188 A

In the conventional pulverized coal-fired boiler described above, secondary air input ports are installed on the outer periphery and upper and lower sides of a coal burner that inputs pulverized coal together with primary air, regardless of the swirl combustion boiler and the counter combustion boiler. The flow rate of the secondary air around the coal burner is adjusted by adjusting the amount of secondary air supplied from the secondary air input port.
Meanwhile, a region where oxygen remains at a high temperature (hereinafter referred to as “high temperature oxygen remaining region”) is formed on the outer periphery of the flame formed in the furnace, and particularly in a region where secondary air is concentrated, high temperature oxygen remains. The region becomes stronger and becomes a factor of increasing the amount of NOx generation.

However, in the conventional swirl combustion boiler and the counter combustion boiler, only the amount of secondary air input from the secondary air input port is adjusted, so the formation of a high temperature oxygen remaining region is suppressed and low NOx is achieved. There was a limit to it.
From such a background, in the conventional swirl combustion boiler, 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. An object of the present invention is to provide a swirl combustion boiler.

In order to solve the above problems, the present invention employs the following means.
In the swirl combustion boiler according to the present invention, the burner for charging pulverized fuel and air into the furnace is a burner portion of a swirl combustion system in which each corner portion is disposed. In the swirl combustion boiler in which a flame is formed, the burner includes a fuel burner for charging pulverized fuel and air, and a secondary air charging port for secondary air charging arranged around the fuel burner, The fuel burner is characterized by comprising fuel dispersion charging means for blowing a part of the pulverized fuel to be injected toward a high temperature and oxygen remaining region on the outer periphery of the flame.

  According to such a swirl combustion boiler, the burner includes a fuel burner that inputs pulverized fuel and air, and a secondary air input port for secondary air input that is disposed around the fuel burner, Since the fuel burner is provided with fuel dispersion charging means for blowing part of the pulverized fuel to be injected toward the high temperature and oxygen remaining area around the flame periphery, the oxygen concentration in the high temperature and oxygen remaining area is reduced. The reduction and chemical cooling effects of the pulverized fuel make it possible to reduce the amount of NOx generated while maintaining the flame holding power.

  In the swirl combustion boiler according to the present invention, the fuel dispersion charging means is preferably a kick mechanism that is provided at an outlet tip of the fuel burner and repels and disperses a part of the pulverized fuel. The flow of pulverized fuel introduced from the fuel burner into the furnace is dispersed by colliding with the kick mechanism, so that a part of the pulverized fuel is introduced toward the high temperature and oxygen remaining area around the flame. As well as being able to produce turbulence in the wake, a flame holding effect can also be expected.

  In the swirl combustion boiler according to the present invention, it is preferable that the fuel dispersion input means is an independent fuel input port provided adjacent to the fuel burner to input a part of the pulverized fuel. The pulverized coal can be supplied to the target location without being affected by the operating conditions of the secondary air.

  In the above invention, it is preferable that the fuel dispersion input means is an auxiliary fuel port that is installed inside or outside the secondary air input port and inputs a part of the pulverized fuel. In this case, if the auxiliary fuel port is inside the secondary air input port, it is possible to effectively supply the pulverized fuel to the high temperature and oxygen remaining region, and the auxiliary fuel port is located outside the secondary air input port. In this case, the pulverized fuel can be supplied without being affected by the flow rate of the secondary air.

  In the swirl combustion boiler according to the present invention, it is preferable that an additional air charging unit is provided at an upper portion of the burner unit, and that the air from the burner unit to the additional air charging unit is used as a reducing atmosphere. The amount of nitrogen oxides generated by the synergistic effect of reducing nitrogen oxides by suppressing the high temperature and residual oxygen concentration region formed around the flame and reducing the nitrogen oxides in the combustion exhaust gas in a reducing atmosphere Can be further reduced.

  According to the present invention described above, a part of the pulverized fuel such as pulverized coal supplied from the fuel burner is dispersedly supplied toward the high temperature and oxygen remaining region outside the flame. It is possible to provide a swirl combustion boiler capable of reducing NOx by suppressing the formed high temperature and oxygen remaining region.

Hereinafter, an embodiment of 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. 5 has a reducing atmosphere in a 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. It aims 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 is a burner for charging powdered fuel such as pulverized coal and air, and 15 is an additional air charging nozzle for charging additional air. In the following description, the swirl combustion boiler 10 is a pulverized fuel. Use pulverized coal as pulverized coal.

  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. The swirl combustion method is used in which one or more swirl flames are formed in each stage. And each burner 20 of the burner part 12 is each arrange | positioned at the upper and lower sides used as the circumference | surroundings of this pulverized coal burner 21, and the secondary air, for example, as shown in FIG. And a secondary air inlet port 30.

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.
An independent secondary air input port 30 is provided above and below the pulverized coal burner 21 for supplying secondary air. Then, fuel dispersion for blowing a part of the pulverized coal supplied as fuel into the pulverized coal burner 21 toward the high temperature oxygen remaining region (high temperature oxygen remaining region) H formed on the outer periphery of the flame F. As an input means, a kick mechanism 40 provided at the outlet front end portion (port opening portion) of the primary coal port 22 to disperse a part of the pulverized coal is provided.

The illustrated kick mechanism 40 includes a pair of upper and lower rod-like members 41 and 42 that divide the outlet opening into three parts across the outlet tip of the primary call port 22, and each has a substantially triangular cross-sectional shape. . That is, the pair of upper and lower bar-shaped members 41 and 42 constituting the kick mechanism 40 forms openings through which the pulverized coal and primary air pass at the center portion and the upper and lower end portions of the coal primary port 22 of the pulverized coal burner 21. In addition, they are arranged in parallel with a predetermined interval in the vertical direction.
Further, the rod-like members 41 and 42 of the kick mechanism 40 use the inclined surface having a triangular cross-sectional shape, so that the flow of pulverized coal passing through the openings at both upper and lower ends formed in the primary call port 22 is guided in the vertical direction. It is attached so that it blows toward the high temperature oxygen residual region H formed in the outer peripheral part of the flame F. That is, the inclined surfaces of the rod-shaped members 41 and 42 give a velocity component in a direction in which the flow of the pulverized coal colliding with the rod-shaped members 41 and 42 is expanded in the vertical direction, so that part of the pulverized coal is indicated by an arrow f in the figure. As shown in the figure, it spreads in the vertical direction and is introduced toward the high temperature oxygen residual region H formed on the outer periphery of the flame F.

  In this way, by blowing a part of the pulverized coal supplied from the pulverized coal burner 21 toward the high temperature oxygen remaining region H formed on the outer periphery of the flame F, the pulverized coal concentration increases outside the flame F. Contributes to improved flame holding. That is, by blowing a part of the pulverized coal supplied from the pulverized coal burner 21 toward the high temperature oxygen residual region H formed on the outer periphery of the flame F, the oxygen concentration in the high temperature oxygen residual region H is reduced and the powder Due to the reduction and chemical cooling effect of the fuel, the amount of NOx generated can be reduced while maintaining the flame holding power. In other words, the flow of the pulverized coal introduced into the furnace 11 from the pulverized coal burner 21 is dispersed by colliding with the kick mechanism 40, so that a part of the pulverized coal is formed at the outer periphery of the flame F. It can be injected toward the oxygen remaining region H. Further, by providing the kick mechanism 40, a flame holding effect can be expected due to the turbulence of the flow generated on the downstream side of the kick mechanism 40.

As the fuel dispersion input means, a first modification example as shown in FIG. 2 may be employed instead of the kick mechanism 40 described above.
In this first modification, a fuel input port 50 adjacent to the pulverized coal burner 21 may be provided as the fuel dispersion means of the burner 20A. This fuel input port 50 is provided independently above and below the pulverized coal burner 21. Accordingly, part of the pulverized coal and primary air is input toward the high-temperature oxygen remaining region H formed on the outer periphery of the flame F through a dedicated flow path branched from the vicinity of the base of the fuel input port 50. Such a fuel input port 50 can supply pulverized coal toward a target location without being affected by the operating conditions on the primary air side input from the pulverized coal burner 21. In addition, the effect | action and effect by blowing a part of pulverized coal toward the high temperature oxygen residual area | region H are the same as that of embodiment mentioned above.

In the second modification shown in FIG. 3 and the third modification shown in FIG. 4, auxiliary fuel input ports 60 and 70 are provided as fuel dispersion input means.
The auxiliary fuel input port 60 shown in FIG. 3 is installed inside the secondary air input port 30A so as to input a part of the pulverized coal toward the high temperature oxygen residual region H. In the illustrated configuration example, a distributor 61 is provided at the tip of the auxiliary fuel input port 60 so that the ratio of the amount of pulverized coal input from the secondary air side can be adjusted. Even if it does in this way, since pulverized coal can be thrown in effectively toward the high temperature oxygen residual area | region H, generation | occurrence | production of NOx can be suppressed.

  Further, the auxiliary fuel injection nozzle 70 shown in FIG. 4 is installed outside the secondary air input port 30A so as to input a part of the pulverized coal toward the high temperature oxygen remaining region H. In the illustrated configuration example, the tip of the auxiliary fuel injection nozzle 70 is bent outward, and the pulverized coal is injected toward the high temperature oxygen residual region H. In this way, although the distance between the burners is widened, it is not affected by the flow rate of the secondary air. Therefore, it becomes possible to accurately input pulverized coal toward the high-temperature oxygen remaining region H, and the high-temperature oxygen remaining Generation of NOx can be suppressed by effectively introducing pulverized coal toward the region H.

  Further, in the above-described swirl combustion boiler 10, the amount of secondary air input from the secondary air input port 30 is distributed between the multistage input of air having a reducing atmosphere in the region from the burner unit 12 to AA14. It is desirable. That is, the secondary air amount input from the divided secondary air input port 30 is input from the secondary air input port 30 by the combined use with the two-stage combustion in which air is input in multiple stages from the AA section 14. The amount of secondary air can be reduced. Therefore, the amount of NOx generated is further reduced by the synergistic effect of reducing NOx by suppressing the high-temperature oxygen residual concentration region H formed on the outer periphery of the flame F and reducing NOx in the combustion exhaust gas in a reducing atmosphere. Can be reduced.

As described above, according to the above-described swirl combustion boiler 10 of the present invention, a part of the pulverized coal supplied from the pulverized coal burner 21 is dispersedly supplied toward the high-temperature oxygen residual region H formed outside the flame F. Therefore, in other words, by adjusting the fuel side instead of the air side, the high-temperature oxygen residual region H formed on the outer periphery of the flame F can be suppressed and the NOx can be reduced. Therefore, by appropriately combining the fuel-side adjustment according to the present invention and the conventional air-side adjustment, it is possible to expand the applicable range of NOx reduction by suppressing the high-temperature oxygen residual region H.
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.

It is a figure which shows one Embodiment of the turning combustion boiler which concerns on this invention, (a) is a longitudinal cross-sectional view which shows the structural example of a burner, (b) is the front view which looked at the burner of (a) from the inside of a furnace. FIG. 2 is a diagram showing a configuration example of a burner having an independent fuel input port as a first modification of the swirl combustion boiler shown in FIG. 1, (a) is a longitudinal sectional view showing a configuration example of the burner, and (b) is ( It is the front view which looked at the burner of a) from the inside of a furnace. It is a longitudinal cross-sectional view which shows the structural example of a burner as the 2nd modification of the turning combustion boiler shown in FIG. It is a longitudinal cross-sectional view which shows the structural example of a burner as a 3rd modification of the turning combustion boiler shown in FIG. It is a figure which shows the structural example of the swirl | burning combustion boiler which is equipped with an additional air injection | throwing-in part, and introduce | transduces air in multistage.

Explanation of symbols

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 22 Cole primary port 23 Cole secondary port 30, 30A, 30B Secondary air input port 40 Kick structure 50 Fuel input port 60, 70 Auxiliary fuel input port F Flame H High temperature oxygen remaining area

Claims (5)

A burner for charging pulverized fuel and air into the furnace is a burner portion of a swirl combustion system arranged at each corner portion or wall surface portion of each stage, and one or a plurality of swirl flames are formed at each stage. In a swirl combustion boiler,
The burner comprises a fuel burner for charging pulverized fuel and air, and a secondary air input port for secondary air input arranged around the fuel burner,
A swirl combustion boiler, characterized in that the fuel burner is provided with fuel dispersion charging means for blowing part of the powdered fuel to be injected toward a high temperature and oxygen remaining region on the outer periphery of the flame.   2. The swirl combustion boiler according to claim 1, wherein the fuel dispersion charging means is a kick mechanism that is provided at an outlet front end portion of the fuel burner and repels and disperses a part of the pulverized fuel. .   The swirl combustion boiler according to claim 1, wherein the fuel dispersion charging means is an independent fuel charging port that is provided adjacent to the fuel burner and into which a part of the pulverized fuel is charged.   The swirl combustion boiler according to claim 1, wherein the fuel dispersion input means is an auxiliary fuel port that is installed inside or outside the secondary air input port and inputs a part of the pulverized fuel. 5. The multistage charging of air is performed, wherein an additional air charging unit is provided at an upper portion of the burner unit, and air is supplied in a reducing atmosphere in a region from the burner unit to the additional air charging unit. A swirl combustion boiler according to claim 1.

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